Top Read Articles
Published in last 1 year |  In last 2 years |  In last 3 years |  All
Please wait a minute...
For Selected: Toggle Thumbnails
Size- and age-dependent increases in tree stem carbon concentration: implications for forest carbon stock estimations
Su-Hui Ma, Anwar Eziz, Di Tian, Zheng-Bing Yan, Qiong Cai, Min-Wei Jiang, Cheng-Jun Ji and Jing-Yun Fang
J Plant Ecol    2020, 13 (2): 233-240.   DOI: 10.1093/jpe/rtaa005
Online available: 04 February 2020

Abstract118)      PDF       Save
Aims

Forest biomass carbon (C) stocks are usually estimated by multiplying biomass by a C conversion factor, i.e. C concentration. Thus, tree C concentration is crucial to the assessments of forest C cycles. As stems contribute to the large fraction of tree biomass, the canonical value of 50% or other simplified values of stem C concentration are widely used to represent the values of tree C concentration in the estimations of forest C stocks at different scales. However, C concentration variations between tree organs and within tree size and their impacts on forest C stocks are still unclear.

Methods

We conducted a global analysis of organ C concentration in age-specific trees based on 576 records of tree age, size (diameter at breast height and biomass) and C concentration data to evaluate the relationships between organ C concentrations and the changes of stem C concentration with tree age and size.

Important Findings

Tree C concentration varied significantly with organs. Stem C concentration of trees was significantly correlated with that of other tree organs, except for barks and reproductive organs. The stem C concentration increased significantly with tree size and age, which contributed to the increases in C contents of stems and trees. Using the C concentration in stems to represent the C concentrations of other organs and the whole tree could produce considerable errors in the estimations of forest C stocks (−8.6% to 25.6% and −2.5% to 5.9%, respectively). Our findings suggest that tree C accumulation in forests is related to the size- and age-dependent increases in stem C concentration and using specific C concentration values of tree organs can improve the estimations of forest C stocks.

Related Articles | Metrics
Changes in niche differentiation and environmental filtering over a hydric stress gradient
Alejandra Martínez-Blancas, and Carlos Martorell
J Plant Ecol    2020, 13 (2): 185-194.   DOI: 10.1093/jpe/rtz061
Online available: 10 January 2020

Abstract95)      PDF       Save
Aims

Diversity in communities is determined by species’ ability to coexist with each other and to overcome environmental stress that may act as an environmental filter. Niche differentiation (ND) results in stronger intra- than interspecific competition and promotes coexistence. Because stress affects interactions, the strength of ND may change along stress gradients. A greater diversity of plant growth forms has been observed in stressful habitats, such as deserts and alpine regions, suggesting greater ND when stress is strong. We tested the hypothesis that niche differences and environmental filters become stronger with stress.

Methods

In a semiarid grassland in southern Mexico, we sowed six annual species in the field along a hydric stress gradient. Plants were grown alone (without interactions), with conspecific neighbors (intraspecific interactions) or with heterospecific neighbors (interspecific interactions). We analyzed how the ratio of intra- to interspecific competition changed along the gradient to assess how water availability determines the strength of ND. We also determined if hydric stress represented an environmental filter.

Important Findings

We observed stronger intra- than interspecific competition, especially where hydric stress was greater. Thus, we found ND in at least some portion of the gradient for all but one species. Some species were hindered by stress, but others were favored by it perhaps because it eliminates soil pathogens. Although strong ND was slightly more frequent with stress, our species sample was small and there were exceptions to the general pattern, so further research is needed to establish if this is a widespread phenomenon in nature.

Related Articles | Metrics
Changes in carbon storages of Fagus forest ecosystems along an elevational gradient on Mt. Fanjingshan in Southwest China
Qiong Cai, Chengjun Ji, Xuli Zhou, Helge Bruelheide, Wenjing Fang, Tianli Zheng, Jiangling Zhu, Lei Shi, Haibo Li, Jianxiao Zhu and Jingyun Fang
J Plant Ecol    2020, 13 (2): 139-149.   DOI: 10.1093/jpe/rtz055
Online available: 16 December 2019

Abstract88)      PDF       Save
Aims

There are different components of carbon (C) pools in a natural forest ecosystem: biomass, soil, litter and woody debris. We asked how these pools changed with elevation in one of China’s ecologically important forest ecosystem, i.e. beech (Fagus L., Fagaceae) forests, and what were the underlying driving factors of such variation.

Methods

The four C pools in nine beech forests were investigated along an elevational gradient (1095–1930 m) on Mt. Fanjingshan in Guizhou Province, Southwest China. Variance partitioning was used to explore the relative effects of stand age, climate and other factors on C storage. In addition, we compared the four C pools to other beech forests in Guizhou Province and worldwide.

Important Findings

The total C pools of beech forest ecosystems ranged from 190.5 to 504.3 Mg C ha–1, mainly attributed to biomass C (accounting for 33.7–73.9%) and soil C (accounting for 23.9–65.5%). No more than 4% of ecosystem C pools were stored in woody debris (0.05–3.1%) and litter (0.2–0.7%). Ecosystem C storage increased significantly with elevation, where both the biomass and woody debris C pools increased with elevation, while those of litter and soil exhibited no such trend. For the Guizhou beech forests, climate and stand age were found to be key drivers of the elevational patterns of ecosystem and biomass C storage, while for beech forests globally, stand age was the most important predictor. Compared to beech forests worldwide, beech forests in Guizhou Province displayed a relatively higher biomass C accumulation rate, which may be explained by a much higher precipitation in this area. The present study provides basic data for understanding the C budgets of Chinese beech forests and their possible roles in regional C cycling and emphasizes the general importance of stand age and climate on C accumulation.

Related Articles | Metrics
Changes in vegetation and soil properties following 6 years of enclosure in riparian corridors
Di Wang, Yi-Ran Zhang, Yu-Long Feng, Zhi Liu and Bo Qu
J Plant Ecol    2020, 13 (2): 131-138.   DOI: 10.1093/jpe/rtaa002
Online available: 06 March 2020

Abstract82)      PDF       Save
Aims

Riparian corridors play vital roles in the maintenance of biodiversity. Nonetheless, plant species diversity and vegetation coverage in riparian corridors are seriously threatened by increasing pressure owing to livestock consumption and anthropogenic disturbance; even the stability of river courses has been threatened. The establishment of enclosures is a widely used strategy to restore degraded grassland ecosystems, but its impact on degraded herbaceous riparian vegetation and soil properties remains unclear. The aim of this study was to evaluate whether species composition, richness, diversity, and soil properties can be recovered by the enclosure.

Methods

Twenty long-term monitoring sample plots were set in the Liaohe main stream river, Liaohe main stream river was enclosed for grazing and farmland exclusion in 2012. The height, coverage and individual numbers of plant were recorded for species richness and diversity evaluation from 2012 to 2017; soil nutrients were measured for comparative analysis in 2012 and 2017. We examined the effects of the establishment of enclosures on plant species diversity and soil properties from 2012 to 2017 in the riparian corridors of the Liaohe River system in China.

Important Findings

Plant species richness and diversity significantly increased from 2012 to 2017. The dominance of Asteraceae plants increased, while the abundance of Gramineae plants decreased over time. The difference in abundance increased each year since enclosure was implemented in 2012. The concentrations of phosphorus and potassium in the soil significantly decreased as a result of the combined effects of vegetation restoration and prohibition of farming practices following the establishment of enclosures. There was also a lag time related to the response of soil organic matter to the establishment of enclosures. In conclusion, our study provides new evidence regarding the response of species diversity, species composition and soil properties following riparian vegetation restoration efforts through enclosure development.

Related Articles | Metrics
The role of soluble sugars during drought in tropical tree seedlings with contrasting tolerances
Michael J. O’Brien, Annabelle Valtat, Samuel Abiven, Mirjam S. Studer, Robert Ong and Bernhard Schmid
J Plant Ecol    2020, 13 (4): 389-397.   DOI: 10.1093/jpe/rtaa017
Online available: 13 April 2020

Abstract76)      PDF       Save
Aims

Non-structural carbohydrates (NSCs) are plant storage compounds used for metabolism, transport, osmoregulation and regrowth following the loss of plant tissue. Even in conditions suitable for optimal growth, plants continue to store NSCs. This storage may be due to passive accumulation from sink-inhibited growth or active reserves that come at the expense of growth. The former pathway implies that NSCs may be a by-product of sink limitation, while the latter suggests a functional role of NSCs for use during poor conditions.

Methods

Using 13C pulse labelling, we traced the source of soluble sugars in stem and root organs during drought and everwet conditions for seedlings of two tropical tree species that differ in drought tolerance to estimate the relative allocation of NSCs stored prior to drought versus NSCs assimilated during drought. We monitored growth, stomatal conductance, stem water potential and NSC storage to assess a broad carbon response to drought.

Important Findings

We found that the drought-sensitive species had reduced growth, conserved NSC concentrations in leaf, stem and root organs and had a larger proportion of soluble sugars in stem and root organs that originated from pre-drought storage relative to seedlings in control conditions. In contrast, the drought-tolerant species maintained growth and stem and root NSC concentrations but had reduced leaf NSCs concentrations with a larger proportion of stem and root soluble sugars originated from freshly assimilated photosynthates relative to control seedlings. These results suggest the drought-sensitive species passively accumulated NSCs during water deficit due to growth inhibition, while the drought-tolerant species actively responded to water deficit by allocating NSCs to stem and root organs. These strategies seem correlated with baseline maximum growth rates, which supports previous research suggesting a trade-off between growth and drought tolerance while providing new evidence for the importance of plasticity in NSC allocation during drought.

Related Articles | Metrics
A sweet new study: tropical forest species use nonstructural carbohydrates in different ways during drought
Jennifer S. Powers
J Plant Ecol    2020, 13 (4): 387-388.   DOI: 10.1093/jpe/rtaa020
Online available: 27 May 2020

Abstract73)      PDF       Save
Related Articles | Metrics
Soil nitrogen availability intensifies negative density-dependent effects in a subtropical forest
Fengmin Huang, Minxia Liang, Yi Zheng, Xubing Liu, Yuxin Chen, Wenbin Li, Shan Luo and Shixiao Yu
J Plant Ecol    2020, 13 (3): 281-287.   DOI: 10.1093/jpe/rtaa012
Online available: 21 March 2020

Abstract72)      PDF       Save
Aims

The importance of density-dependent mortality in maintaining tree species diversity is widely accepted. However, density-dependent effects may vary in magnitude and direction with different abiotic conditions in forests. Theoretical predictions surmise that density-dependent effects may vary with soil available nitrogen (AN), but this still needs to be tested.

Methods

We analyzed the density-dependent effects on survival of newly germinated seedlings for 18 common species based on a long-term seedling census across environmental gradients in a subtropical forest. We also conducted a root lesion detection experiment for five species to investigate the potential effects of pathogens on variation in density-dependent disease between rich and poor AN environments.

Important Findings

The seedling dynamics analysis revealed that the strength of density-dependent effects increased with AN, shifting from neutral or positive with low AN to negative with high AN. Three of the five tree species had stronger density-dependent effects on root lesions in rich AN environments than in poor AN environments, which is consistent with the results of a long-term seedling dynamics analysis. We also found higher species diversity in rich AN environments, which may be promoted by the stronger negative density-dependent effects. Both the seedling dynamic analysis and root lesion detection experiment revealed stronger negative density-dependent effects in higher AN environment, resulting from stronger disease pressure by soil pathogens. Our study emphasized the importance of considering context dependence when testing the density dependence hypotheses.

Related Articles | Metrics
Woody plant encroachment may decrease plant carbon storage in grasslands under future drier conditions
Yun-Hua Liu, Jun-Hui Cheng, Bernhard Schmid, Li-Song Tang and Jian-Dong Sheng
J Plant Ecol    2020, 13 (2): 213-223.   DOI: 10.1093/jpe/rtaa003
Online available: 23 January 2020

Abstract69)      PDF       Save
Aims

Woody plants are widely distributed in various grassland types along the altitudinal/climatic gradients in Xinjiang, China. Considering previously reported change in carbon (C) storage following woody plant encroachment in grasslands and the mediating effect of climate on this change, we predicted that a positive effect of woody plants on plant C storage in semiarid grasslands may revert to a negative effect in arid grasslands. We first investigated the spatial variation of aboveground C (AGC) and belowground C (BGC) storage among grassland types and then tested our prediction.

Methods

We measured the living AGC storage, litter C (LC) and BGC storage of plants in two physiognomic types, wooded grasslands (aboveground biomass of woody plants at least 50%) and pure grasslands without woody plants in six grassland types representing a gradient form semiarid to arid conditions across Xinjiang.

Important Findings Living AGC, LC, BGC and total plant C storage increased from desert to mountain meadows. These increases could also be explained by increasing mean annual precipitation (MAP) or decreasing mean annual temperature (MAT), suggesting that grassland types indeed represented an aridity gradient. Woody plants had an effect on the plant C storage both in size and in distribution relative to pure grasslands. The direction and strength of the effect of woody plants varied with grassland types due to the mediating effect of the climate, with wetter conditions promoting a positive effect of woody plants. Woody plants increased vegetation-level AGC through their high AGC relative to herbaceous plants. However, more negative effects of woody plants on herbaceous plants with increasing aridity led to a weaker increase in the living AGC in arid desert, steppe desert and desert steppe than in the less arid other grassland types. Under greater aridity (lower MAP and higher MAT), woody plants allocated less biomass to roots and had lower BGC and had a more negative impact on herbaceous plant production, thereby reducing vegetation-level BGC in the desert, steppe desert and desert steppe. In sum, this resulted in a negative effect of woody plants on total plant C storage in the most arid grasslands in Xinjiang. As a consequence, we predict that woody plant encroachment may decrease rather than increase C storage in grasslands under future drier conditions.

Related Articles | Metrics
Resource enrichment combined with biomass removal maintains plant diversity and community stability in a long-term grazed grassland
Feng-Wei Xu, Jian-Jun Li, Li-Ji Wu, Xiao-Ming Lu, Wen Xing, Di-Ma Chen, Biao Zhu, Shao-Peng Wang, Lin Jiang and Yong-Fei Bai
J Plant Ecol    2020, 13 (5): 611-620.   DOI: 10.1093/jpe/rtaa046
Online available: 21 July 2020

Abstract66)            Save
Aims

Long-term heavy grazing reduces plant diversity and ecosystem function by intensifying nitrogen (N) and water limitation. In contrast, the absence of biomass removal can cause species loss by elevating light competition and weakening community stability, which is exacerbated by N and water enrichment. Hence, how to maintain species diversity and community stability is still a huge challenge for sustainable management of worldwide grasslands.

Methods

We conducted a 4-year manipulated experiment in six long-term grazing blocks to explore combination of resource additions and biomass removal (increased water, N and light availability) on species richness and community stability in semiarid grasslands of Inner Mongolia, China.

Important Findings

In all blocks treated with the combination of resource additions and biomass removal, primary productivity increased and species richness and community stability were maintained over 4 years of experiment. At both species and plant functional group (PFG) levels, the aboveground biomass of treated plants remained temporally stable in treatments with the combination of N and/or water addition and biomass removal. The maintenance of species richness was primarily caused by the biomass removal, which could increase the amount of light exposure for grasses under resource enrichment. Both species asynchrony and stability of PFGs contributed to the high temporal stability observed in these communities. Our results indicate that management practices of combined resource enrichment with biomass removal, such as grazing or mowing, could not only enhance primary productivity but also maintain plant species diversity, species asynchrony and community stability. Furthermore, as overgrazing-induced degradation and resource enrichment-induced biodiversity loss continue to be major problems worldwide, our findings have important implications for adaptive management in semiarid grasslands and beyond.

Related Articles | Metrics
Species-specific responses to drought, salinity and their interactions in Populus euphratica and P. pruinosa seedlings
Lei Yu, Haojie Dong, Zhijun Li, Zhanjiang Han, Helena Korpelainen and Chunyang Li
J Plant Ecol    2020, 13 (5): 563-573.   DOI: 10.1093/jpe/rtaa043
Online available: 17 July 2020

Abstract65)      PDF       Save
Aims

Drought and salinity are severe abiotic stress factors, which limit plant growth and productivity, particularly in desert regions. In this study, we employed two desert poplars, Populus euphratica Oliver and Populus pruinosa Schrenk seedlings, to compare their tolerance to drought, salinity and combined stress.

Methods

We investigated species-specific responses of P. euphratica and P. pruinosa in growth, photosynthetic capacity and pigment contents, nonstructural carbohydrate concentrations, Cl allocation, osmotic regulation and the accumulation of reactive oxygen species (ROS) under drought, salinity and the combined stress.

Important Findings

Populus pruinosa exhibited greater growth inhibitory effects, photosynthesis decline, stomatal closure and ROS accumulation, and lower antioxidant enzyme activities and osmotic regulation compared with P. euphratica under drought, salinity and especially under their combined stress. On the other hand, salt-stressed P. euphratica plants restricted salt transportation from roots to leaves, and allocated more Cl to coarse roots and less to leaves, whereas salt-stressed P. pruinosa allocated more Cl to leaves. It was shown that there is species-specific variation in these two desert poplars, and P. pruinosa suffers greater negative effects compared with P. euphratica under drought, salinity and especially under the combined stress. Therefore, in ecological restoration and afforestation efforts, species-specific responses and tolerances of these two poplar species to drought and salinity should be considered under climate change with increasing drought and soil salinity developing.

Related Articles | Metrics
Physiological dormancy broken by endozoochory: Austral parakeets (Enicognathus ferrugineus) as legitimate dispersers of calafate (Berberis microphylla) in the Patagonian Andes
Carolina Bravo, Daniel Chamorro, Fernando Hiraldo, Karina Speziale, Sergio A. Lambertucci, José L. Tella and Guillermo Blanco
J Plant Ecol    2020, 13 (5): 538-544.   DOI: 10.1093/jpe/rtaa041
Online available: 16 July 2020

Abstract59)      PDF       Save
Aims

Seed dispersal by endozoochory is an important process in plant regeneration and the establishment of new populations. Seeds with dormancy may especially benefit after disperser gut passage. However, the ways in which gut passage affect the germination of plant species with physiological dormancy remain unclear. Here, we experimentally assessed the mutualistic interaction between the Austral parakeet (Enicognathus ferrugineus) as a disperser of calafate (Berberis microphylla), a thorny bush inhabiting the understory of the Austral temperate forests of South America with seeds that are characterized by deep physiological dormancy.

Methods

Germination success and viability of calafate seeds obtained from faeces and from intact fruits were tested under four treatments: (i) digested seeds, (ii) digested seeds with faecal extract, (iii) intact seeds from fruit and (iv) intact seeds from fruit with pulp.

Important Findings

About 65% of the Austral parakeet droppings contained calafate seeds. Viability of seeds did not differ between treatments. However, germination was significantly higher in digested seeds than in intact seeds from fruits, while no difference was found between faecal and pulp extracts. Neither faecal matter nor fruit pulp provided seeds with any ecological advantages derived from enhancing germinability, but did confer some disadvantage in germination time. Faecal matter is expected to be completely lacking around seeds after several months under snow before germinating in the following spring, given intense washing due to persistent rain and the spring thaw in the Patagonian Andes. The higher germinability along with faster germination of digested seeds supports the hypothesis of a legitimate mutualistic interaction between Austral parakeets and calafate. We hypothesized that the passage through the disperser digestive tract might break physiological dormancy as differences in germinability between ingested and non-ingested seeds. Our results highlight the relevant role of endozoochory in plant species with physiological dormancy living in highly seasonal environments.

Related Articles | Metrics
Species turnover drives grassland community to phylogenetic clustering over long-term grazing disturbance
Juntao Zhu , Yangjian Zhang, Wenfeng Wang, Xian Yang , Ning Chen , Ruonan Shen , Li Wang and Lin Jiang
J Plant Ecol    2020, 13 (2): 157-164.   DOI: 10.1093/jpe/rtz057
Online available: 23 December 2019

Abstract56)      PDF       Save
Aims

Grazing exerts profound effects on grassland ecosystem service and functions by regulating species composition and diversity, and structuring community assembly worldwide. However, adaptions of phylogenetic diversity and phylogenetic community structure to long-term grazing disturbance remain poorly studied, especially for ecosystems distributed in extreme environments.

Methods

Here, we conducted an experiment with multigrazing intensities to explore the impacts of grazing disturbance on plant phylogenetic diversity and community structure in an alpine grassland of the Tibetan Plateau.

Important Findings

Grazing disturbance enriched plant species richness (SR), and stimulated species turnover from regional species pool, consequently changing community species composition. Under low intensities, grazing exerted no obvious effects on phylogenetic diversity and community structure, whereas communities changed from overdispersion to clustering under high grazing intensity. High grazing intensity resulted in stronger environmental filtering, which consequently selected those species with high resilience to grazing disturbance. The observed clustering structure was associated with the colonizing species which were closely related to resident species, and locally extinct species, and distantly related to residents. At the plant functional trait level, high grazing intensity increased species colonization largely by altering the effect of root depth on species colonization compared to light grazing. Our results highlight that solely utilization of SR and diversity cannot fully represent grassland communities responses to grazing. The effects of species turnover on community phylogenetic diversity and structure are entailed to be explored in the future grazing studies.

Related Articles | Metrics
Variability of water supply affected shoot biomass and root depth distribution of four temperate grassland species in monocultures and mixtures
Eamon Haughey, Jennifer C. McElwain and John A. Finn
J Plant Ecol    2020, 13 (5): 554-562.   DOI: 10.1093/jpe/rtaa044
Online available: 21 July 2020

Abstract52)      PDF       Save
Aims

Research on the effects of extreme rainfall events on ecosystem function has primarily focussed on drought or flooding events, which usually include changes to mean or total rainfall, annually or over a season. However, less is known about the effects of increased rainfall variability without change to mean or total amounts. We investigated the effects of increased variation of water supply on shoot and root biomass as well as the distribution of root biomass of four grassland plant species, grown in monoculture and mixture communities.

Methods

Perennial ryegrass (Lolium perenne L., shallow-rooting grass), chicory (Cichorium intybus L., deep-rooting forb), white clover (Trifolium repens L., shallow-rooting legume) and red clover (Trifolium pratense L., deep-rooting legume) were established in mesocosms. Four plants of the same species were grown in monoculture communities and one of each species grown in four-species communities. Water supply was manipulated such that; compared with a baseline level with low variation in water supply, there was a treatment with medium variation (±40%) and another with high variation (±80%). Shoot and root biomass were measured, and vertical root distribution models fitted.

Important Findings

Compared with the low variation treatment, shoot biomass was significantly reduced under high variation for white clover, red clover and four-species communities. Under all conditions, four-species communities produced more shoot and root biomass than predicted by species performance in monoculture (overyielding). Under increased water variation, chicory monocultures allocated a higher proportion of root biomass to deeper soil layers while the total root biomass of white clover monocultures was significantly reduced. These results indicate that increased variability of water supply can negatively affect the shoot and root biomass production of single and multi-species grasslands. There is a need for further investigation of water variation effects on the functioning of multi-species grassland systems at field 

Related Articles | Metrics
Physiological and biomass partitioning shifts to water stress under distinct soil types in Populus deltoides saplings
Senlin Yang, Jian Shi, Lianghua Chen, Jian Zhang, Danju Zhang, Zhenfeng Xu, Jiujin Xiao, Peng Zhu, Yang Liu, Tiantian Lin, Li Zhang, Hanbo Yang and Yu Zhong
J Plant Ecol    2020, 13 (5): 545-553.   DOI: 10.1093/jpe/rtaa042
Online available: 16 July 2020

Abstract51)      PDF       Save
Aims

Although soil environments exist extensive heterogeneity for many plants with a wide range of distribution, researches about effects of soil conditions on plants’ tolerance and adaptation are particularly inadequate. In our study, the aims are to reveal physiological strategies of Populus deltoides against drought stress under different soil conditions and to select the most suitable soil type for Pdeltoides plantation.

Methods

Under controlled conditions, we used P. deltoides as a model species to detect differences in gas exchange rate, antioxidative capacity, nitrogen metabolism and biomass accumulation and partitioning in response to drought stress under three mineral soil types with distinct physicochemical characters, i.e. red soil (RS), yellow soil (YS) and yellow-brown soil (BS).

Important Findings

Exposure to 25% of field water holding capacity in soil for 3 months had significantly decreased biomass of all organs, photosynthetic rate, enzyme activities related to N assimilation, but increased H2O2, malondialdehyde and content of both NO3 and NH4+, when P. deltoideswas planted in both RS and YS. In contrast, under BS, there are slightly negative effects exerted by water deficit on total biomass, gas exchange rate, activities of enzymes related to nitrogen metabolism and membrane damage caused by reactive oxygen species, which can be associated with a consistent increase in superoxide dismutase, peroxidase and catalase, and a higher ratio of root mass to shoot mass. It is concluded that, such higher capacity in tolerance and adaptation against drought stress under BS relative to both RS and YS could be accounted for more sufficient nutrient provision in soil parental materials and better soil aeration conditions which play a vital role in plant acclimation to water shortage. Our study also revealed that, distribution areas of BS might be preferable for cultivation of Pdeltoides, when compared with those of RS and YS.

Related Articles | Metrics
Climate drives differences in the germination niche of a globally distributed invasive grass
Rebecca A. Fletcher, Kayla M. Varnon and Jacob N. Barney
J Plant Ecol    2020, 13 (2): 195-203.   DOI: 10.1093/jpe/rtz062
Online available: 06 January 2020

Abstract49)      PDF       Save
Aims

Exotic invasive species are often exposed to strong selection pressures in their new ranges that can often lead to substantial intraspecific variation. Population differentiation in the timing of life history events in response to climate gradients is thought to be an important mechanism facilitating the range expansion of many invasive species. For seed producing plants, the timing of seed germination determines the first environmental conditions experienced by newly emerged germinates, and can have important implications for the successful colonization, establishment and spread of invasive plants—though the role of germination in the success of invasive plants remains poorly understood.

Methods

We assessed the variation in seed germination dynamics among 10 populations of the invasive plant Johnsongrass (Sorghum halepense) across its North American distribution, capturing both a temperature and precipitation gradient, and whether that variation is associated with home climate. Seeds were exposed to a wide range of temperatures (11–48°C) and two water availability treatments.

Important Findings

We found that Johnsongrass seeds germinated across a wide range of temperatures, but there was substantial variation among populations in the proportion of seeds that germinated in response to both temperature and water availability. Evidence indicates that as Johnsongrass expanded its range from warmer climates into cooler climates, there was a concurrent shift in the germination temperature niche to cooler temperatures. Our results suggest that the germination of Johnsongrass seeds has adapted to home climate allowing this invader to maximize germination throughout its range, and that this may be an important contributing factor to its invasion into new environments.

Related Articles | Metrics
Contrasting responses of native and alien plant species to soil properties shed new light on the invasion of dune systems
Stefano Vitti, Elisa Pellegrini, Valentino Casolo, Giacomo Trotta and Francesco Boscutti
J Plant Ecol    2020, 13 (6): 667-675.   DOI: 10.1093/jpe/rtaa052
Online available: 11 August 2020

Abstract49)      PDF       Save
Aims

Among terrestrial ecosystems, coastal sandy dunes are particularly prone to alien plant invasion. Many studies related the invasion of dune habitats to anthropic causes, but less is known about the role of soil properties and plant traits in plant invasion. In this study, we tested the relationships between soil features and alien plant invasion in dune systems, focusing on the interplay between soil nutrients, soil salinity and plant functional traits.

Methods

Study sites were sandy barrier islands of the Marano and Grado lagoon (northern Adriatic Sea). One hundred plots (4 m × 4 m) were selected within 10 areas according to the main habitats occurring along the ecological gradient of dune system (foredune, backdune and saltmarsh). In each plot, we recorded all plant species occurrence and abundance and we collected a soil core. For each soil sample, soil texture, conductivity (as proxy of soil salinity), organic carbon and nitrogen content were analyzed and related to the species number and cover of native and alien plants. Variation of main reproductive and vegetative functional traits among habitats was also analyzed for both alien and native species.

Important Findings

Soil properties were strongly related to overall plant diversity, by differently affecting alien and native species pools. In backdune, the most invaded habitat, a high soil conductivity limited the number of alien species, whereas the content of soil organic carbon increased along with alien plant abundance, suggesting also the occurrence of potential feedback processes between plant invasion and soil. We found a significant convergence between native and alien plant functional trait spectra only in backdune habitat, where environmental conditions ameliorate and plant competition increases. Our findings suggest that in harsh conditions only native specialized plants can thrive while at intermediate conditions, soil properties gradient acts in synergy with plant traits to curb/facilitate alien plant richness.

Related Articles | Metrics
Aboveground biomass and seasonal patterns of aboveground net primary productivity in five bamboo species in northern Laos
Singkone Xayalath, Isao Hirota, Shinsuke Tomita and Michiko Nakagawa
J Plant Ecol    2020, 13 (2): 150-156.   DOI: 10.1093/jpe/rtz056
Online available: 23 December 2019

Abstract48)      PDF       Save
Aims

Accurate estimates of bamboo biomass and net primary productivity (NPP) are required to evaluate the carbon sequestration potential of bamboo forests. However, relevant data that are important for climate change mitigation, have rarely been collected in regions outside of East Asia and India. Information on seasonal patterns of NPP and its components will enable the quantification of factors that influence the carbon balance in bamboo forests. In this study, we quantified the aboveground biomass (AGB) and aboveground NPP of five major bamboo species in northern Laos using monthly data collected over a 12-month period.

Methods

All live culms in 10, 2 m × 2 m plots (for one monopodial bamboo species: Indosasa sinica) and 30 clumps per species (for four sympodial bamboo species: Bambusa tuldaCephalostachyum virgatumDendrocalamus membranaceus and Gigantochloa sp.) were numbered and measured at breast height. We set 10 or 20 litter traps per species to collect litterfall. Censuses of dead and recruited culms and litterfall collection were performed once per month for 12 months.

Important Findings

The AGB was highest in I. sinica (59.87 Mg ha−1) and lowest in Cvirgatum (11.54 Mg ha−1), and was mostly below the plausible global range for bamboos (32–256 Mg ha−1). The sympatric distribution of multiple bamboo species at the study sites may have suppressed the AGB in four of the five studied species. The aboveground NPP estimates were between 3.43 and 14.25 Mg ha−1 yr−1; those for D. membranaceus (8.20 Mg ha−1 yr−1) and I. sinica(14.25 Mg ha−1 yr−1) were comparable to mean global estimates for temperate evergreen forests (8.78 Mg ha−1 yr−1) and tropical moist forests (10.56 Mg ha−1yr−1). High culm recruitment rates (15.20–23.39% yr−1) were major contributors to aboveground NPP estimates. Seasonal patterns of aboveground NPP were largely influenced by the phenology of the new culms. In the four sympodial bamboo species, new culms began to emerge following the onset of persistent rainfall, mainly in July and August. However, the sprouting of new culms in the monopodial species I. sinica followed a trend of increasing temperatures, mainly in March and April. Thus, our results indicate that bamboos have considerable potential for sequestering carbon in northern Laos, but that this potential may be affected by climate change.

Related Articles | Metrics
The ultraviolet colour component enhances the attractiveness of red flowers of a bee-pollinated plant
Zhe Chen, Chang-Qiu Liu, Hang Sun and Yang Niu
J Plant Ecol    2020, 13 (3): 354-360.   DOI: 10.1093/jpe/rtaa023
Online available: 25 May 2020

Abstract48)      PDF       Save
Aims

Bee-pollinated flowers are rarely red, presumably because bees (which lack red receptors) have difficulty detecting red targets. Although the response of bees to red colour has been investigated in lab experiments, most stimuli have been pure red, while the subtle diversity of red as perceived by humans (human-red) has received very limited attention. Here we test the hypothesis that ultraviolet (UV) reflected from human-red flowers enhances their attractiveness to bees, through increased chromatic contrast.

Methods

Using Onosma confertum (Boraginaceae), a plant with UV-reflecting red flowers that are pollinated by bumblebees, we investigated the effects of UV reflection on pollinator responses by conducting phenotypic manipulation experiments in the field. Colour preferences of flower-naïve bumblebees were also examined. Colour perception by bumblebees was estimated in terms of chromatic and achromatic contrast, based on two different colour perception models.

Important Findings

We found that both natural and flower-naïve bumblebees strongly preferred visiting UV-reflecting targets compared with UV-absorbing ones. Colour models show that the UV-reflecting flowers exhibit higher spectral purity and higher chromatic contrast against the foliage background, whereas they have similar achromatic contrast in terms of green receptor contrast. These results indicate that the component of UV reflection increases chromatic contrast in O. confertum, enhancing the visual attractiveness of these red flowers to bumblebees. We further infer that the secondary reflectance might be a necessary component in human-red flowers that are primarily pollinated by animals without red receptors, such as bees.

Related Articles | Metrics
In the beginning, there was only bare regolith—then some plants arrived and changed the regolith
Jun Zhou, Alejandra Zúñiga-Feest and Hans Lambers
J Plant Ecol    2020, 13 (5): 511-516.   DOI: 10.1093/jpe/rtaa030
Online available: 06 July 2020

Abstract47)      PDF       Save
Related Articles | Metrics
Characteristics of fungal community structure during the decomposition of mixed foliage litter from Pinus massoniana and broadleaved tree species in southwestern China
Yan Zhang, Xun Li, Danju Zhang, Yu Qin, Yang Zhou, Simeng Song and Jian Zhang
J Plant Ecol    2020, 13 (5): 574-588.   DOI: 10.1093/jpe/rtaa045
Online available: 26 July 2020

Abstract47)      PDF       Save
Aims

The conifer litter is fairly recalcitrant and nutrient poor, and broadleaved litter promotes coniferous litter decomposition by increasing degradable nutrients and promoting microbial metabolism. Mixing Pinus massoniana litter and three broadleaved litters may increase the diversity and abundance of fungal decomposers compared with those in P. massoniana litter and vary depending on the number and proportion of broadleaved species included.

Methods

We analysed the composition and diversity of fungal communities during mixed litter decomposition in southwestern China with 35 treatments (P. massonianaToona sinensisCinnamomum camphora and Sassafras tzumu litter) using Illumina high-throughput sequencing.

Important Findings

The mixed litters increased fungal diversity and richness compared with those in the single-species litter, except in the following treatments: P. massoniana litter accounting for 70%–80% in the P. massoniana + T. sinensisP. massoniana + S. tzumu + T. sinensis and P. massoniana + S. tzumu + C. camphora combinations, and P. massoniana + S. tzumu + C. camphora + T. sinensis combination with small proportion of T. sinensis litter. The diversity and richness of the 7:1:2 combination of P. massoniana + C. camphora + T. sinensis were significantly higher than those in the other treatments. Ascomycota and Basidiomycota were the dominant phyla, and Aspergillus was the most abundant genus. The decomposition of litters from one needleleaf and one broadleaved species (6:4) and one needleleaf species and two broadleaved species (broadleaved litter accounting for 30%–40%) exhibited synergistic interactions throughout the decomposition process, and the relative abundance of fungi that decompose refractory substances increased. The P. massoniana + C. camphora + T. sinensis combination and a 30%–40% broadleaf litter proportion increased fungal diversity and accelerated the decomposition of recalcitrant coniferous litter. Therefore, C. camphora and T. sinensis are a potential candidate species for mixed planting with P. massoniana.

Related Articles | Metrics
Variation in the methods leads to variation in the interpretation of biodiversity–ecosystem multifunctionality relationships
Xin Jing, Case M. Prager, Aimée T. Classen, Fernando T. Maestre, Jin-Sheng He and Nathan J. Sanders
J Plant Ecol    2020, 13 (4): 431-441.   DOI: 10.1093/jpe/rtaa031
Online available: 11 June 2020

Abstract47)      PDF       Save
Aims

Biodiversity is often positively related to the capacity of an ecosystem to provide multiple functions simultaneously (i.e. multifunctionality). However, there is some controversy over whether biodiversity–multifunctionality relationships depend on the number of functions considered. Particularly, investigators have documented contrasting findings that the effects of biodiversity on ecosystem multifunctionality do not change or increase with the number of ecosystem functions. Here, we provide some clarity on this issue by examining the statistical underpinnings of different multifunctionality metrics.

Methods

We used simulations and data from a variety of empirical studies conducted across spatial scales (from local to global) and biomes (temperate and alpine grasslands, forests and drylands). We revisited three methods to quantify multifunctionality including the averaging approach, summing approach and threshold-based approach.

Important Findings

Biodiversity–multifunctionality relationships either did not change or increased as more functions were considered. These results were best explained by the statistical underpinnings of the averaging and summing multifunctionality metrics. Specifically, by averaging the individual ecosystem functions, the biodiversity–multifunctionality relationships equal the population mean of biodiversity-single function relationships, and thus will not change with the number of functions. Likewise, by summing the individual ecosystem functions, the strength of biodiversity–multifunctionality relationships increases as the number of functions increased. We proposed a scaling standardization method by converting the averaging or summing metrics into a scaling metric, which would make comparisons among different biodiversity studies. In addition, we showed that the range-relevant standardization can be applied to the threshold-based approach by solving for the mathematical artefact of the approach (i.e. the effects of biodiversity may artificially increase with the number of functions considered). Our study highlights different approaches yield different results and that it is essential to develop an understanding of the statistical underpinnings of different approaches. The standardization methods provide a prospective way of comparing biodiversity–multifunctionality relationships across studies.

Related Articles | Metrics
The asymmetric relationships of the distribution of conspecific saplings and adults in forest fragments
Jinliang Liu, Yuchen Zhong, Lei Zhong, Boliang Wei, Shilu Zheng, Yuchu Xie, Yi Jin and Mingjian Yu
J Plant Ecol    2020, 13 (4): 398-404.   DOI: 10.1093/jpe/rtaa026
Online available: 26 May 2020

Abstract44)      PDF       Save
Aims

With the increase of land-use change, habitat fragmentation has become a major factor affecting plant diversity. Generally, when the adult density is high, the survival rate of conspecific saplings may decline and provide more resources and space for other species to maintain a high local species diversity. Therefore, the spatial relationship of conspecific saplings and adults (SRCSA) can regulate plant diversity. However, very few studies have assessed SRCSA within fragmented forests, and we still largely unknown the relationship between SRCSA and species diversity in fragmented landscapes.

Methods

We calculated the mean strength of SRCSA using the spatial distribution data of saplings and adults with a log-transformed hierarchical offset-power model on 27 islands in a land-bridge island system. The higher strength of SRCSA reflects a more negative relationship between the density of conspecific saplings and adults on an island (i.e. the looser pattern of SRCSA). We tested the relationships among island attributes (i.e. island area, the distance to the mainland—MD, and the distance to the nearest island—ND), SRCSA and species diversity.

Important Findings

The strength of SRCSA increased with ND. Meanwhile, the species diversity significantly increased with the strength of SRCSA, and island area and the strength of SRCSA independently explained 26% and 6% of variation of species diversity, respectively, and their interactions explained 8%. Shade-intolerant and low-abundant species showed looser patterns of SRCSA. Our study suggests that SRCSA may have the effect of excluding species with a relatively low abundance in isolated island forests, which illustrates the importance of biotic interactions in maintaining plant diversity in fragmented forests. Our results also emphasize that we should consider forest connectivity when testing the conspecific negative density dependence.

Related Articles | Metrics
Genotypic diversity and genotype identity of resident species drive community composition
Věroslava Hadincová, Hana Skálová and Zuzana Münzbergová
J Plant Ecol    2020, 13 (2): 224-232.   DOI: 10.1093/jpe/rtaa004
Online available: 04 February 2020

Abstract40)      PDF       Save
Aims

Species-rich plant communities are more resistant to invasions. In the past decade it was demonstrated that genetic variation also has many ecological effects. In our study we aimed to test whether the patterns of response to the genetic diversity of a resident species differ between colonizing species of different growth forms and whether the response is affected by soil nutrients.

Methods

We established experimental stands of a common grass, Festuca rubra, harbouring three levels of genetic diversity (1, 6 or 18 clonal genotypes, referred to as genotypic diversity) under two soil nutrient levels. In the fourth year after the stands were established, we sowed a mixture of four colonizers into the stands: a stoloniferous legume (Trifolium repens), a broad-leaf tussock grass (Anthoxanthum odoratum), a large-rosette forb (Plantago lanceolata) and a small-rosette forb (Campanula rotundifolia). We observed species establishment and growth over 3 years. We tested whether colonization success depended on genotypic diversity, specific Festuca genotypes, soil nutrients and colonizer growth form.

Important Findings

The colonization success and biomass of the colonizers were significantly affected by the genotypic diversity and the genotype identity of the resident clonal grass. The response, however, differed between the colonizers. The strongest response to the genotypic diversity of the resident species was observed in the tussock grass with a growth form and architecture similar to the resident species. The large-rosette species responded in early stages of growth whereas the stoloniferous legume did not respond at all. The intraspecific genotypic diversity and genotype identity of the resident species play an important role in the assembly of plant communities.

Related Articles | Metrics
Impact of forest fire on soil seed bank composition in Himalayan Chir pine forest
Bobbymoore Konsam, Shyam S. Phartyal and Nagendra P. Todaria
J Plant Ecol    2020, 13 (2): 177-184.   DOI: 10.1093/jpe/rtz060
Online available: 27 December 2019

Abstract40)      PDF       Save
Aims

To explain how plant community copes with a recurring anthropogenic forest fire in Himalayan Chir pine forest, it is important to understand their postfire regeneration strategies. The primary aim of the study was to know: (i) how fire impact soil seed bank composition and (ii) how much soil seed bank composition differs with standing vegetation after the forest fire.

Methods

Soil samples were collected from burned and adjoining unburned sites in blocks using three layers down to 9 cm depth immediately after a forest fire and incubated in the net-house for seedling emergence. Same sites were revisited during late monsoon/early autumn season to know the species composition of standing vegetation recovered after a forest fire.

Important Findings

Soil contained viable seeds of >70 species. The average seed bank density was 8417 and 14 217 seeds/m2 in the burned and unburned site, respectively. In both sites, it decreased with increasing soil depth. Overall fire had no significant impact on seed density; however, taking individual layers into consideration, fire had a significant impact on seed density only in the uppermost soil layer. The species richness of soil seed bank and standing vegetation was 73 and 100, respectively (with 35 shared species), resulting in a similarity of about 40%. In contrast, >80% species in soil seed bank was found similar between burned and unburned sites. Further, there were no significant differences in species richness of standing vegetation in burned (87 spp.) and unburned (78 spp.) sites. Our results showed that fire had an insignificant impact on soil seed bank composition and restoration potential of a plant species from seeds. The understory herb and shrub plant community’s ability to form a fire-resistant viable soil seed bank and capable to recover in the postfire rainy season, explains how they reduce the risk of recurring fire damage in maintaining their population.

Related Articles | Metrics
The assembly of plant-patch networks in Mediterranean alpine grasslands
David S. Pescador, José María Iriondo, Gianalberto Losapio and Adrián Escudero
J Plant Ecol    2020, 13 (3): 273-280.   DOI: 10.1093/jpe/rtaa011
Online available: 14 March 2020

Abstract40)      PDF       Save
Aims

Harsh environmental conditions in alpine ecosystems shape vegetation structure into patches, where many different plant species cluster and grow together. Yet, which factors are important for the structure and dynamics of such plant–patch networks remains poorly understood. We aim to assess which and how environmental and biotic factors predict the assembly of plant–patch networks along a mountain range.

Methods

We examined the distribution of plant species in more than 5500 vegetation patches in 37 Mediterranean alpine grasslands distributed along a 500 m altitudinal gradient (National Park of Sierra Guadarrama, Spain). We established a plant–patch network for each grassland community and analyzed how nestedness and modularity vary with environmental (altitude, insolation and soil conditions) and biotic factors (number of species per plot, mean patch area and total pasture area).

Important Findings

Plant–patch networks showed consistent, non-random patterns characterized by a nested, but not modular, structure, which suggests that positive associations among co-occurring specialists promote their growth within patches as subsets of a pool with more generalist species. Both nestedness and modularity of plant–patch networks varied among grasslands. Specifically, nestedness decreased with increasing species per plot and increased with mean patch area, while it was independent of environmental variables; modularity increased with increasing pasture area and species per plot. The negative relationship between species per plot and nested patterns may be linked to the restricted number of species that can coexist within the same patch at a given size. Moreover, the positive relationship between patch size and nestedness indicates that the growth of rare plant species within vegetation patches occupied by more abundant species is facilitated in bigger rather than smaller patches. Furthermore, these results indicate that the nested assembly of vegetation patches may be independent of abiotic conditions. These findings suggest that large and unfragmented vegetation patches are fundamental for the maintenance of plant diversity in alpine grasslands. Looking at species distribution at fine spatial scales may shed new light on the biotic processes underlying plant network assembly and provide novel ways for conserving biodiversity.

Related Articles | Metrics
Growth, phenology and N-utilization by invasive populations of Gunnera tinctoria
Maurício Cruz Mantoani , Alberto Benavent González, Leopoldo García Sancho and Bruce Arthur Osborne
J Plant Ecol    2020, 13 (5): 589-600.   DOI: 10.1093/jpe/rtaa047
Online available: 21 July 2020

Abstract40)      PDF       Save
Aims

Gunnera tinctoria is an unusual N-fixing plant species that has become invasive worldwide, generally in environments with a low evaporative demand and/or high rainfall. Amongst the many mechanisms that may explain its success as an introduced species, a contrasting phenology could be important but this may depend on an ability to grow and utilize nutrients under sub-optimal conditions. We examined whether G. tinctoria has an advantage in terms of a contrasting phenology and N-fixing capability, in comparisons with Juncus effusus, the native species most impacted by G. tinctoria invasions.

Methods

We made phenological assessments on a weekly or bi-weekly basis on long-established populations on Achill Island, Ireland, during 2016–2017. Data on leaf and inflorescence number, total leaf area, light interception and above-ground biomass were collected alongside measurements of soil temperature, moisture and oxidation–reduction potential. The significance of N-fixing ability for supporting seasonal growth was assessed using δ 15N isotopic assessments, together with in situ acetylene reduction measurements.

Important Findings

The timing of the initiation of growth of G. tinctoria and J. effusus varied between 2016 and 2017, with the earlier emergence and expansion of leaves of G. tinctoria, and the largest above-ground biomass associated with higher water availability. The early growth of G. tinctoria was dependent on preformed structures, with maximum canopy development occurring in late May, prior to that of J. effusus. Whilst N-fixation was observed in March, this made a more significant contribution to growth during the later stages of canopy development. Based on δ 15N isotopic analyses, early growth was predominantly associated with N-remobilization from the rhizomes, whilst seedlings were largely reliant on N-fixation. This emphasizes the importance of nutrient mobilization for early growth and shows that the importance of an N-fixing capability may vary developmentally, as well as during different stages of the invasion process.

Related Articles | Metrics
Effects of warming on soil respiration during the non-growing seasons in a semiarid temperate steppe
Yuan Miao, Mengzhou Liu, Juan Xuan, Wei Xu, Shilin Wang, Renhui Miao, Dong Wang, Wei Wu, Yinzhan Liu and Shijie Han
J Plant Ecol    2020, 13 (3): 288-294.   DOI: 10.1093/jpe/rtaa013
Online available: 07 April 2020

Abstract38)      PDF       Save
Aims

The response pattern of terrestrial soil respiration to warming during non-growing seasons is a poorly understood phenomenon, though many believe that these warming effects are potentially significant. This study was conducted in a semiarid temperate steppe to examine the effects of warming during the non-growing seasons on soil respiration and the underlying mechanisms associated therewith.

Methods

This experiment was conducted in a semiarid temperate grassland and included 10 paired control and experimental plots. Experimental warming was achieved with open top chambers (OTCs) in October 2014. Soil respiration, soil temperature and soil moisture were measured several times monthly from November 2014 to April 2015 and from November 2015 to April 2016. Microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and available nitrogen content of soil were measured from 0 to 20 cm soil depth. Repeated measurement ANOVAs and paired-sample t tests were conducted to document the effect of warming, and the interactions between warming and time on the above variables. Simple regressions were employed to detect the underlying causality for the observed effects.

Important Findings

Soil respiration rate was 0.24 µmol m−2 s−1 in the control plots during the non-growing seasons, which was roughly 14.4% of total soil carbon flux observed during growing seasons. Across the two non-growing seasons, warming treatment significantly increased soil temperature and soil respiration by 1.48°C (P < 0.001) and 42.1% (P < 0.01), respectively, when compared with control plots. Warming slightly, but did not significantly decrease soil moisture by 0.66% in the non-growing seasons from 2015 to 2016. In the non-growing seasons 2015–16, experimental warming significantly elevated MBC and MBN by 19.72% and 20.99% (both P < 0.05), respectively. In addition, soil respiration responses to warming were regulated by changes in soil temperate, MBC and MBN. These findings indicate that changes in non-growing season soil respiration impact other components in the carbon cycle. Additionally, these findings facilitate projections regarding climate change–terrestrial carbon cycling.

Related Articles | Metrics
Linking the spatiotemporal variation of litterfall to standing vegetation biomass in Brazilian savannas
Alan N. Costa, Jeane R. Souza, Karyne M. Alves, Anderson Penna-Oliveira, Geisciele Paula-Silva, Ingrid S. Becker, Kelly Marinho-Vieira, Ana L. Bonfim, Alessandra Bartimachi and Ernane H. M. Vieira-Neto
J Plant Ecol    2020, 13 (5): 517-524.   DOI: 10.1093/jpe/rtaa039
Online available: 16 July 2020

Abstract37)      PDF       Save
Aims

Litterfall at a global scale is affected by climate, edaphic features and vegetation structure, with litter production increasing from grasslands to forests following the rise in standing biomass. However, at landscape scales, the same relationship between litter production and vegetation structure has rarely been studied and comparisons of litterfall patterns between adjacent, structurally distinct communities are lacking. Here, we use a standardized methodology to describe the structural differences among four savanna physiognomies and analyze their relationship with changes in litterfall across the Cerrado.

Methods

We evaluated the woody vegetation structure and composition in 48 sites, equally distributed across four physiognomies and monitored the monthly litter production from April 2014 to March 2015.

Important Findings

Results showed that the density, basal area, cylindrical volume and aboveground biomass of woody vegetation differ among physiognomies, increasing consistently from cerrado ralocerrado típicocerrado denso and cerradão. Indeed, we found a strong and positive relationship between aboveground biomass and annual litter production, with litter yield increasing from 0.9 to 8.4 Mg ha−1 across different physiognomies, following the increment in vegetation structure. Monthly production was seasonal and similar among vegetation types, increasing during the dry season. Leaves comprised the dominant fraction (approx. 85%) and litterfall seasonality primarily resulted from the concentration of leaf shedding during dry months. However, the temporal pattern of litterfall throughout the year showed a gradual reduction in the seasonality from open to closed vegetation types, likely following the decrease of deciduous species abundance in the plant community. Our results showed that changes in vegetation structure may affect spatial and temporal litterfall patterns in different physiognomies, which co-occur across the Cerrado landscape, with potential implications for the overall functioning of this ecosystem. Moreover, these findings highlight the use of standardized methods as essential to correctly compare litterfall patterns among different environments.

Related Articles | Metrics
The impacts of warming and nitrogen addition on competitive ability of native and invasive populations of Plantago virginica
Xi Luo, Yi Zheng, Xiaohong Xu, Rui Xiao and Hui Guo
J Plant Ecol    2020, 13 (6): 676-682.   DOI: 10.1093/jpe/rtaa055
Online available: 08 August 2020

Abstract36)      PDF       Save
Aims

Global change factors (e.g. warming and nitrogen deposition) may influence biological invasions, but how these factors may influence the performance of invasive species and further mediate the interactions with native competitors remain still unknown.

Methods

Here, we conducted a 5-month greenhouse experiment to examine the effects of warming (using open-top chambers, +0.62°C) and N addition (adding NH4NO3 at a rate of 4.2 g m−2) on the performance of the native and invasive populations of an invasive species Plantago virginica in competition with a native Plantago asiatica.

Important Findings

Under warming treatment and its interaction with nitrogen addition treatment (W × N), invasive and native populations of P. virginica had different biomass allocation strategies to compete with native competitor P. asiatica. Native population of P. virginica (PV-Na) increased more below-ground biomass, whereas those from the invasive population (PV-In) increased more above-ground biomass. We also found that invasive species P. virginica had stronger responses to warming and N addition than the native species P. asiatica. The competitive ability of the invasive plants was significantly reduced by warming which indicated that the invasive plant were much stronger sensitivity to elevated temperature than native plant. Similarly, N addition and W × N reduced the competitive response of PV-In in below-ground biomass, but increased the competitive response of PV-Na in above-ground and total biomass when they grew with the P. asiatica. The results show that P. virginica have occurred differential biomass allocation strategies during its invasions and invasive population exhibit flexible competition ability to adapt to environmental changes (especially warming). These findings may potentially help to predict plant invasions and make management strategies in a world with changing climate.

Related Articles | Metrics
Germination strategies under climate change scenarios along an aridity gradient
Alexander Zogas, Evsey Kosman and Marcelo Sternberg
J Plant Ecol    2020, 13 (4): 470-477.   DOI: 10.1093/jpe/rtaa035
Online available: 29 June 2020

Abstract34)      PDF       Save
Aims

Climate change in the eastern Mediterranean region will have a strong impact on ecosystem functioning and plant community dynamics due to a reduction in annual rainfall and increased variability. We aim to understand the role of seed banks as potential buffers against climatic uncertainty determined by climate change.

Methods

We examined germination strategies of 18 common species present along an aridity gradient. Data were obtained from soil seed banks germinated during nine consecutive years from arid, semi-arid, Mediterranean and mesic Mediterranean ecosystems. At the semi-arid and Mediterranean sites, rainfall manipulations simulating 30% drought and 30% rainfall increase were applied. Germination strategies were tested under optimal irrigation conditions during three consecutive germination seasons to determine overall seed germinability in each soil sample. Changes in germination strategy were examined using a novel statistical approach that considers the climatic and biotic factors that may affect seed germinability.

Important Findings

The results showed that dominant species controlled their germination fractions by producing seeds with a different yearly germination fraction probability. The amount of rainfall under which the seeds were produced led to two major seed types with respect to germinability: high germinability, seeds leading to transient seed banks, and low germinability, seeds leading to persistent seed banks. We conclude that differential seed production among wet and dry years of both seed types creates a stable balance along the aridity gradient, enabling the soil seed bank to serve as a stabilizing mechanism buffering against rainfall unpredictability. Additionally, we present a general model of germination strategies of dominant annual species in Mediterranean and arid ecosystems that strengthens the notion of soil seed banks as buffers against climatic uncertainty induced by climate change in the region.

Related Articles | Metrics
Linking plant spatial aggregation with reproductive traits and near-source seed dispersal: ecological adaptation to heavy grazing
Wenting Liu, Shixian Sun, Chunping Zhang, Shijie Lv and Quanmin Dong
J Plant Ecol    2020, 13 (4): 489-498.   DOI: 10.1093/jpe/rtaa036
Online available: 29 June 2020

Abstract34)      PDF       Save
Aims

Ecological strategies related to the adaptation of plants to environmental stress have long been studied by ecologists, but few studies have systematically revealed the ecological process of plant adaptation to herbivores as a whole.

Methods

In this study, Stipa breviflora, the dominant species in the desert steppe of Inner Mongolia, was used to analyse its reproductive individual characteristics and seed traits as well as the soil seed bank and spatial patterns under heavy-grazing and no-grazing treatments.

Important Findings

The results showed that the number of reproductive branches positively affected the number of vegetative branches. The analysis of the soil seed bank showed that the density of S. breviflora seeds beneath reproductive S. breviflora individuals was significantly higher than that in bare land. The seed density was also significantly negatively correlated with the seed characteristics and the soil seed bank in bare land. The spatial distribution of S. breviflora was aggregated under heavy grazing. Our results suggest that under heavy grazing, reproductive activity plays a key role in resource allocation. Stipa breviflora evolved the ecological strategy of nearby diffusion by regulating the morphological characteristics of the seeds, which promotes a positive spatial correlation between the juvenile and adult populations at a small scale, thus leading to the formation of ‘safe islands’.

Related Articles | Metrics
Effect of nitrate supply on the facilitation between two salt-marsh plants (Suaeda salsa and Scirpus planiculmis)
Hua Ma, Li-Juan Cui, Xu Pan, Wei Li, Yu Ning and Jian Zhou
J Plant Ecol    2020, 13 (2): 204-212.   DOI: 10.1093/jpe/rtaa001
Online available: 07 January 2020

Abstract32)      PDF       Save
Aims

In estuarine salt-marshes, nitrate supply and soil salinity, which are known as two main environmental drivers, simultaneously affect the interspecific interactions between plant species. However, to date, their interactive effects on interspecific interactions have not been closely examined for salt-marsh plant species.

Methods

Juvenile plants of Suaeda salsa L. (Chenopodiaceae) and Scirpus planiculmis Fr. (Cyperaceae) were grown in rinsed river sand to conduct a greenhouse experiment with three treatment categories: interspecific interaction (mixed culture or monoculture), three salinity levels (1, 50 and 100 mmol L−1) and three nitrate levels (0.5, 5 and 10 mmol L−1). First, height and biomass of all plants were measured. Then, the growth data, relative interaction index and competitive important index of the two species were analyzed.

Important Findings

The interspecific interactions between S. salsa and S. planiculmis were facilitation across the salinity gradients. The promotion of S. salsa growth with high nitrate supply did not enhance the facilitative effect of the species, especially at low salinity. However, high nitrate supply significantly shifted the interspecific interactions of S. planiculmisfrom facilitation to competition at high salinity. Our results suggest that excessive nitrate application changes the prediction of the stress-gradient hypothesis along a salinity gradient, leading to collapse of the two species coexistence in the salt-marshes. These findings make a contribution to the understanding of how S. salsaand S. planiculmis, as well as salt-marsh communities, respond to the human modification of estuarine nutritional levels.

Related Articles | Metrics
Seed bank dynamics of an invasive alien species, Helianthus annuus L.
Alejandro Presotto, Fernando Hernández, Mauricio Casquero, Roman Vercellino, Claudio Pandolfo , Mónica Poverene and Miguel Cantamutto
J Plant Ecol    2020, 13 (3): 313-322.   DOI: 10.1093/jpe/rtaa016
Online available: 13 April 2020

Abstract32)      PDF       Save
Aims

The ability to form persistent seed banks is one of the best predictors of species’ potential to establish in new ranges. Wild sunflower is native to North America where the formation of persistent seed banks is promoted by disturbance and it plays a key role on the establishment and persistence of native populations. However, the role of the seed banks on the establishment and persistence of invasive populations has not been studied. Here, we evaluated the role of seed bank and disturbance on the establishment and fitness, and seed persistence in the soil in several sunflower biotypes collected in ruderal (wild Helianthus annuus) and agrestal (natural crop–wild hybrid) habitats of Argentina as well as volunteer populations (progeny of commercial cultivars).

Methods

In a seed-bank experiment, we evaluated emergence, survival to reproduction, survival of emerged seedlings, inflorescences per plant and per plot under disturbed and undisturbed conditions over 2 years; in a seed-burial experiment, we evaluated seed persistence in the soil over four springs (6, 18, 30 and 42 months).

Important Findings

Overall, seedling emergence was early in the growing season (during winter), and it was promoted by disturbance, especially in the first year. Despite this, the number of inflorescences per plot was similar under both conditions, especially in ruderals. In the second year, emergence from the seed bank was much lower, but the survival rate was higher. In the seed-burial experiment, genetic differences were observed but seeds of ruderals and agrestals persisted up to 42 months while seeds of the volunteer did not persist longer than 6 months. The agrestal biotype showed an intermediate behavior between ruderals and volunteers in both experiments. Our findings showed that wild and crop–wild sunflower can form persistent seed banks outside its native range and that disturbance may facilitate its establishment in new areas.

Related Articles | Metrics
Importance of starting points in heterogeneous environments: interactions between two clonal plants with contrasting spatial architectures
Wei Xue, Lin Huang and Fei-Hai Yu
J Plant Ecol    DOI: 10.1093/jpe/rtaa018
Accepted: 19 June 2020
Online available: 04 May 2020

Abstract32)      PDF       Save
The relative controls of temperature and soil moisture on the start of carbon flux phenology and net ecosystem production in two alpine meadows on the Qinghai-Tibetan Plateau
Xi Chai, Peili Shi, Minghua Song , Ning Zong, Yongtao He, Yingnian Li, Xianzhou Zhang and Yanjiao Liu
J Plant Ecol    2020, 13 (2): 247-255.   DOI: 10.1093/jpe/rtaa007
Online available: 13 February 2020

Abstract31)      PDF       Save
Aims

Variations in vegetation spring phenology are widely attributed to temperature in temperate and cold regions. However, temperature effect on phenology remains elusive in cold and arid/semiarid ecosystems because soil water condition also plays an important role in mediating phenology.

Methods

We used growing degree day (GDD) model and growing season index (GSI) model, coupling minimum temperature (Tmin) with soil moisture (SM) to explore the influence of heat requirement and hydroclimatic interaction on the start of carbon uptake period (SCUP) and net ecosystem productivity (NEP) in two alpine meadows with different precipitation regimes on the Qinghai-Tibet Plateau (QTP). One is the water-limited alpine steppe-meadow, and the other is the temperature-limited alpine shrub-meadow.

Important Findings

We observed two clear patterns linking GDD and GSI to SCUP: SCUP was similarly sensitive to variations in preseason GDD and GSI in the humid alpine shrub-meadow, while SCUP was more sensitive to the variability in preseason GSI than GDD in the semiarid alpine steppe-meadow. The divergent patterns indicated a balance of the limiting climatic factors between temperature and water availability. In the humid meadow, higher temperature sensitivity of SCUP could maximize thermal benefit without drought stress, as evidenced by the stronger linear correlation coefficient (R2) and Akaike’s information criterion (AIC) between observed SCUPs and those of simulated by GDD model. However, greater water sensitivity of SCUP could maximize the benefit of water in semiarid steppe-meadow, which is indicated by the stronger R2 and AIC between observed SCUPs and those of simulated by GSI model. Additionally, although SCUPs were determined by GDD in the alpine shrub-meadow ecosystem, NEP was both controlled by accumulative GSI in two alpine meadows. Our study highlights the impacts of hydroclimatic interaction on spring carbon flux phenology and vegetation productivity in the humid and semiarid alpine ecosystems. The results also suggest that water, together with temperature should be included in the models of phenology and carbon budget for alpine ecosystems in semiarid regions. These findings have important implications for improving vegetation phenology models, thus advancing our understanding of the interplay between vegetation phenology, productivity and climate change in future.

Related Articles | Metrics
Dynamics in the emergence of dormant and non-dormant herbaceous species from the soil seed bank from a Brazilian dry forest
José Djalma de Souza, Bruno Ayron de Souza Aguiar, Danielle Melo dos Santos, Vanessa Kelly Rodrigues de Araujo, Júlia Arruda Simões, Juliana Ramos de Andrade and Elcida de Lima Araújo
J Plant Ecol    2020, 13 (3): 256-265.   DOI: 10.1093/jpe/rtaa008
Online available: 04 March 2020

Abstract31)      PDF       Save
Aims

In dry tropical forests, herbaceous species may have dormancy mechanisms and form persistent and transient seed banks in the soil. Evolutionarily acquired, these mechanisms are efficient for the establishment and survival of these herbs, especially in forests with unpredictable climates, such as the Caatinga. Thus, our objective was to verify whether the studied herbaceous species adopt the physical dormancy mechanism and how these natural barriers are overcome, to understand the temporal dynamics existing in the soil seed bank from a Brazilian dry tropical forest.

Methods

Seeds of five native herbaceous species from the Caatinga forests were selected and submitted to pre-germinative treatments for verifying the presence of physical dormancy. We collected soil samples in the rainy and dry seasons for four consecutive years and monitored the emergence of the selected herbaceous in the greenhouse. We verified the differences in germination and seed bank emergence in the soil by generalized linear models.

Important Findings

The presence and absence of physical dormancy were observed in seeds from Caatinga herbaceous species. We found intraspecific and interspecific differences in the herbaceous emergence from soil seed banks between years and climatic seasons. In perennial herbs, consecutive lack of emergence between seasons and years was frequent, which suggests a direct relationship with the mechanism of physical dormancy and the environmental conditions necessary to overcome integument barriers. In these species, seed dimorphism and dormancy may confer additional advantages to their survival. Moreover, presenting intermediate levels of physical dormancy in an annual species may be an evolutionary adjustment to rainfall unpredictability. In contrast, we found that the annual herb without dormancy is more sensitive to seasonal and interannual climate changes, as evidenced by the increase and significant reduction of its emergence in the soil seed bank. These differences acquired evolutionarily are advantageous for the establishment of herbaceous populations, mainly in semiarid regions with an unpredictable climate.

Related Articles | Metrics
Fluorescence characterization and microbial degradation of dissolved organic matter leached from salt marsh plants in the Yellow River Delta
Tao Zhang, Zhihua Feng, Chunle Luo, Yixin Sun, Jinzhen Li, Juntian Xu and Xuchen Wang
J Plant Ecol    2020, 13 (5): 525-537.   DOI: 10.1093/jpe/rtaa040
Online available: 21 July 2020

Abstract31)      PDF       Save
Aims

Salt marsh vegetation is an important contributor of dissolved organic matter (DOM) to coastal waters. The dynamics of DOM leaching from different marsh plants, however, have not been well studied or compared.

Methods

In this study, we conducted laboratory experiments to investigate the processes of DOM leaching from three common marsh plants (Phragmites australisSuaeda salsa and Aeluropus littoralis) collected from the Yellow River Delta (YRD) salt marsh in October 2016. The YRD is one of the largest and most well-protected coastal ecosystems on the east coast of China.

Important Findings

We found that the plant leaves released DOM at much higher concentrations than the plant roots or stems, as measured by the dissolved organic carbon (DOC) and dissolved nitrogen (DN). On average, 15% of the biomass C and 30% of the biomass N were released from the plant leaves as DOC and DN during the 27-day incubation period. The DOM released from the plants was very labile, and 92.4%–98.1% of the DOC and 88.0%–94.6% of the DN released from the plants were consumed by bacteria during the 27-day incubation period. The fluorescence characteristics of the plant-released DOM indicated that chromophoric dissolved organic matter was a major fraction of the DOM and that protein-like components were the primary organic fractions released from the plants. Bacterial degradation altered both the fluorescence properties and the chemical composition of the DOM. The results of the laboratory experiments were well supported by the field investigation, which indicated that a large amount of DOM was outwelled from the YRD salt marshes in late autumn. Our study suggests that the DOM released from the biomass of salt marsh plants provides an important source of both DOC and DN for marsh and coastal waters. The highly labile DOC and DN provide essential food sources to support microbial communities in the YRD salt marsh and adjacent coastal waters.

Related Articles | Metrics
Protection status as determinant of carbon stock drivers in Cerrado sensu stricto
Kelly Marianne Guimarães Pereira, Natielle Gomes Cordeiro, Marcela de Castro Nunes Santos Terra, Marcela Venelli Pyles, Christian Dias Cabacinha, José Márcio de Mello and Eduardo van den Berg
J Plant Ecol    2020, 13 (3): 361-368.   DOI: 10.1093/jpe/rtaa024
Online available: 25 May 2020

Abstract30)      PDF       Save
Aims

Natural vegetation plays an important role in global carbon cycling and storage. Thus, the Cerrado (Brazilian savannah) is considered a carbon sink because of its intrinsic characteristics. Our aim was to evaluate how the aboveground biomass and biodiversity relationship change between three Cerrado remnants with different protection status: a ‘control area’ (Legal Reserve area), a protected area (PA) and a non-protected area (Non-PA).

Methods

All three studied fragments are situated in northern Minas Gerais state, Brazil. We estimated the aboveground carbon stocks based on the forest inventory. We also measured three dimensions of biodiversity metrics for each plot: functional trait dominance, taxonomic diversity and functional diversity. The following functional traits were evaluated for the species: wood density, maximum diameter and seed size. We carried out generalized linear models seeking to evaluate how carbon stocks, community-weighted mean (CWM) trait values, species richness and diversity, and functional diversity indices differ among the remnants.

Important Findings

The Cerrado areas without protection status had lower carbon stocks, species richness, species diversity, functional richness and functional dispersion, whereas both PA and Non-PA had lower CWM maximum diameter and seed size compared with the Legal Reserve control area. Generalized linear models showed that carbon stocks, species and functional richness metrics were correlated within and across sites, and thus, species richness could serve as a good proxy for functional richness and carbon stocks. The carbon stocks were positively driven by species richness and CWM maximum diameter, while they were negatively driven by functional dispersion. Functional richness, species diversity and CWM seed size appeared in the set of best models, but with no significant direct effect on carbon stocks. Thus, we concluded that absence of protection in the Cerrado areas decreases both species richness and carbon stocks.

Related Articles | Metrics
Scale dependence in the phylogenetic relatedness of alien and native taxa
Chris M. McGrannachan, Gillis J. Horner and Melodie A. McGeoch
J Plant Ecol    2020, 13 (5): 601-610.   DOI: 10.1093/jpe/rtaa048
Online available: 09 August 2020

Abstract29)      PDF       Save
Aims

Darwin’s naturalization hypothesis proposes that successfully established alien species are less closely related to native species due to differences in their ecological niches. Studies have provided support both for and against this hypothesis. One reason for this is the tendency for phylogenetic clustering between aliens and natives at broad spatial scales with overdispersion at fine scales. However, little is known about how the phylogenetic relatedness of alien species alters the phylogenetic structure of the communities they invade, and at which spatial scales effects may manifest. Here, we examine if invaded understorey plant communities, i.e. containing both native and alien taxa, are phylogenetically clustered or overdispersed, how relatedness changes with spatial scale and how aliens affect phylogenetic patterns in understorey communities.

Methods

Field surveys were conducted in dry forest understorey communities in south-east Australia at five spatial scales (1, 20, 500, 1500 and 4500 m2). Standardized effect sizes of two metrics were used to quantify phylogenetic relatedness between communities and their alien and native subcommunities, and to examine how phylogenetic patterns change with spatial scale: (i) mean pairwise distance and (ii) mean nearest taxon distance (MNTD).

Important Findings

Aliens were closely related to each other, and this relatedness tended to increase with scale. Native species and the full community exhibited either no clear pattern of relatedness with increasing spatial scale or were no different from random. At intermediate spatial scales (20–500 m2), the whole community tended towards random whereas the natives were strongly overdispersed and the alien subcommunity strongly clustered. This suggests that invasion by closely related aliens shifts community phylogenetic structure from overdispersed towards random. Aliens and natives were distantly related across spatial scales, supporting Darwin’s naturalization hypothesis, but only when phylogenetic distance was quantified as MNTD. Phylogenetic dissimilarity between aliens and natives increased with spatial scale, counter to expected patterns. Our findings suggest that the strong phylogenetic clustering of aliens is driven by human-mediated introductions involving closely related taxa that can establish and spread successfully. Unexpected scale-dependent patterns of phylogenetic relatedness may result from stochastic processes such as fire and dispersal events and suggest that competition and habitat filtering do not exclusively dominate phylogenetic relationships at fine and coarse spatial scales, respectively. Distinguishing between metrics that focus on different evolutionary depths is important, as different metrics can exhibit different scale-dependent patterns.

Related Articles | Metrics
Soil and climate equally contribute to changes in the species compositions of Brazilian dry forests across 300 km
Daniel M. Arruda, Luiz F. S. Magnago, Ricardo R. C. Solar, Reinaldo Duque-Brasil, Priscyla M. S. Rodrigues, Rubens M. Santos and Carlos E. G. R. Schaefer
J Plant Ecol    2020, 13 (2): 171-176.   DOI: 10.1093/jpe/rtz059
Online available: 02 January 2020

Abstract28)      PDF       Save
Aims

Understanding the factors that control biodiversity distributions at different spatial scales has been a key challenge for conservation efforts. That biodiversity, reflected in differences in species compositions among sites (beta diversity), can be derived from species replacement (turnover) and is driven by multiple factors. Here, we sought to tackle this issue through two questions related to threatened Brazilian seasonally dry forests: (i) what is the contribution of species turnover to beta diversity? and (ii) which factors drive variations in species compositions among forest patches?

Methods

We sampled tree species and environmental variables (soils and climate) in 17 dry forest patches spaced almost 300 km apart. We used the beta diversity partitioning framework to determine the contribution of turnover. We used redundancy analysis, with properly controlled spatial structure, to assess the contributions of the environmental and spatial factors to the variations of the species composition.

Important Findings

Beta diversity among the patches was mainly represented by the turnover component (98.2%), with Simpson dissimilarity superior to other regions of the country (means of 0.89 and 0.71 in multiple site and pairwise measures, respectively). The environmental factors measured explained more than space, representing 30.3% of the variation of the species composition, of which 28.1% was nonspatially structured. We suggest that 300 km represents a threshold at which edaphic and climatic predictors have similar effects in determining community turnover (14.9% and 12.6%, respectively, without spatial structure). Thus, conservation strategies should be considered across landscapes to effectively protect tropical forest diversity, as even considering the different climatic aspects covered by the scale, landscaped edaphic varieties are important drivers of species turnover.

Related Articles | Metrics
Impact Factor
1.833
5 year Impact Factor
2.299
Editors-in-Chief
Wen-Hao Zhang
Bernhard Schmid