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  • Volume 11 Issue 1
    An invasive population of Gunnera tinctoria growing on Achill Island, Co Mayo, Ireland. Photograph taken in June 2017 by Mauricio Mantoani.
    Bruce Osborne, Margherita Gioria
    2018, 11 (1): 1-3.
    Abstract ( 151 )   PDF   Save
    Margherita Gioria, Petr Pyšek, Bruce A. Osborne
    2018, 11 (1): 4-16.
    Abstract ( 174 )   PDF   Save
    Aims Plant invasions represent a unique opportunity to study the mechanisms underlying community assembly rules and species distribution patterns. While a superior competitive ability has often been proposed as a major driver of successful plant invasions, its significance depends crucially on the timing of any competitive interaction. We assess whether a mismatch in germination phenology can favor the establishment of alien species, allowing them to exploit vacant niches where competition is low. As well as having important effects on the survival, growth and fitness of a species, asymmetric competition and potential soil legacies resulting from early or late germination can also impact on species recruitment. However, early or late germination comes at a cost, increases the risks of exposure to unfavorable conditions and requires an enhanced abiotic resistance if it is to lead to successful establishment.
    Important findings While there are several anecdotal accounts of early and late germination for invasive species, there are limited comparative data with resident species growing under natural conditions. Available evidence from grassland communities indicates that a short-term germination advantage or priority (few days/weeks) provides invasive species with a strong competitive advantage over native species and is a critical factor in many invasions. While the exploitation of periods of low competition is a plausible mechanism for the successful establishment of many invasive plants, direct evidence for this strategy is still scarce. This is particularly true with regard to the exploitation of late germination niches. Consequently, long-term comparative monitoring of the germination phenology of invasive and native plants in situ is needed to assess its significance in a range of ecosystems and its impact on community dynamics.
    Bin Zhu, Cora C. Ottaviani, Rahmat Naddafi, Zhicong Dai, Daolin Du
    2018, 11 (1): 17-25.
    Abstract ( 226 )   PDF   Save
    Aims European frogbit (Hydrocharis morsus-ranae L.) is an aquatic plant originating from Europe that has emerged as an invasive species, spreading in the USA and Canada since it was first brought to North America in 1932. It can now be found in many water bodies, from small ponds and long rivers to large lakes such as Lake Ontario and Lake Erie. The continuous spread of this species indicates its success as an invasive species despite legislative attempts to limit its distribution. Catling et al. (Catling PM, Miltrow G, Haber E, et al. (2003) The biology of Canadian weeds. 124. Hydrocharis morsus-ranae L. Can J Plant Sci 83:1001–16) wrote a thorough review about this invasive species in North America. Our review aims for a compilation of the most recent available data and recent studies on H. morsus-ranae L. and focuses primarily on its environmental uses, ecological impacts and management. The purpose of this review is to offer an organized and updated report on European frogbit that can be used towards future studies with the goal of eradicating this invasive species and providing insights on management of other invasive plants.
    Important findings Our findings reveal that European forgbit's ecological effects on other species and the invaded environment were shown to be less harmful than previously feared. European frogbit had negative impacts on native plants and reduced dissolved oxygen concentration. However, water chemistry, phytoplankton and zooplankton communities were actually not affected by European frogbit. For fungi, bacteria and macroinvertebrates, studies have showed complex and sometimes conflicting results. We also specifically discussed the new method to control this species using shading and the more recent studies on biological control. Shading with a shade cloth has been shown to effectively remove European frogbit and had minor environmental effects. However, using biological control to combat the spread of the invasive frogbit seems not as successful as we wished.
    Research Articles
    Cristina Antunes, Ana Júlia Pereira, Patrícia Fernandes, Margarida Ramos, Lia Ascensão, Otília Correia, Cristina Máguas
    2018, 11 (1): 26-38.
    Abstract ( 261 )   PDF   Save
    Aims Mediterranean coastal dunes are habitats of great conservation interest, with a distinctive and rich flora. In the last century, Acacia spp., native from Australia, have been introduced in Portugal, with the objective of stabilizing sand dunes, and since have become dominant in numerous sand dune habitats. This invasion process led to the reduction of native plant species richness, changed soil characteristics and modified habitat's microclimatic characteristics. The aim of this research was to typify and compare, in Mediterranean sand dune ecosystems, the ecophysiological responses to drought of Helichrysum italicum and Corema album, two native species, and Acacia longifolia, an exotic invasive species. We addressed the following specific objectives: (i) to compare water relations and water use efficiencies, (ii) to evaluate water stress, (iii) to assess water use strategies and water sources used by plants and (iv) to evaluate the morphological adaptations at leaf and phyllode level.
    Methods In order to obtain an integrative view of ecophysiological patterns, water relations and performance measuring methods have been applied: predawn (ψ PD) and midday (ψ MD) water potential, chlorophyll a fluorescence, oxygen isotopic composition of xylem, rain and groundwater (δ 18 O) and leaf carbon isotopic discrimination (Δ 13 C). The leaf characteristics of the three species, as well as the histochemistry of non-glandular trichome cell walls, were also studied to identify morpho-traits related to drought resistance.
    Important findings The results support our initial hypothesis: although A. longifolia clearly possesses a degree of resistance to water stress, such ability is provided by a different water strategy, when compared to native species. Natives relied on morphological adaptations to restrict water loss, whereas the invasive species adjusted the water uptake as a way to balance their limited ability of restricting water loss. We corroborate that woody native species (i) have a conservative water-saving strategy and minor seasonal variations relative to invasive species, (ii) use enriched water sources during drought periods, indicating different water sources and root systems comparing with invasive species and (iii) present drought leaf morpho-functional adaptations related with limiting water loss. Comparing the physiological performance of invasive and native species can offer causal explanations for the relative success of alien plant invasions on sand dunes ecosystems.
    Xiaolong Huang, Ligong Wang, Xin Guan, Yuanyuan Gao, Chunhua Liu, Dan Yu
    2018, 11 (1): 39-46.
    Abstract ( 211 )   PDF   Save
    Aims Aquatic plants play an important role in freshwater ecosystems. Previous works have largely focused on the functional significance of plant above ground parts, with much less attention on the root structures of aquatic plants. In this study, we divided 21 aquatic plants (including five introduced plants) into multiple plant groups (different life forms, monocot/eudicot and introduced/native) with the goal of addressing two questions: (i) what root structures do aquatic plants exhibit, and (ii) are there differences among these plant groups?
    Methods Twenty-one aquatic plants belonging to four life forms (free-floating, emergent, floating-leaved and submerged) were collected at the near flowering stage from a typical macrophyte-dominated lake in the Yangtze River Basin, China. The following root topological parameters were quantified: altitude (a), path length (p e), magnitude (M), mean topological length (b), topological index (TI) and normed indices q a and q b .
    Important findings The root topological indices TI, q a and q b for the 21 aquatic plants were 0.724 ± 0.013, 0.290 ± 0.031 and 0.152 ± 0.024 (means ± S.E.), respectively, revealing a general pattern of dichotomous branching, except for the aquatic root of Myriophyllum aquaticum (Vell.) Verdc., which displays herringbone branching. All three topological indices were significantly lower for monocots (TI = 0.700 ± 0.130, q a = 0.191 ± 0.149 and q b = 0.086 ± 0.236) than eudicots (TI = 0.752 ± 0.206, q a = 0.405 ± 0.569 and q b = 0.229 ± 0.393), indicating that the roots of monocots are typically more dichotomous-like than those of eudicots. Among the four life forms, the three topological indices for emergent plants (TI = 0.832 ± 0.006, q a = 0.616 ± 0.018 and q b = 0.381 ± 0.014) were significantly higher than those of the other three life forms. Overall, there was no difference between the topological indices of introduced and native aquatic plants, but the introduced species M. aquaticum and Alternanthera philoxeroides (Mart.) Griseb. had both aquatic and edaphic roots as well as unusual functions, which may help explain their strong viability.
    Alexandra R. Collins, Brian Beckage, Jane Molofsky
    2018, 11 (1): 47-55.
    Abstract ( 196 )   PDF   Save
    Aims We aim to understand how small-scale genotypic richness and genotypic interactions influence the biomass and potential invasiveness of the invasive grass, Phalaris arundinacea under two different disturbance treatments: intact plots and disturbed plots, where all the native vegetation has been removed. Specifically, we address the following questions (i) Does genotypic richness increase biomass production? (ii) Do genotypic interactions promote or reduce biomass production? (iii) Does the effect of genotypic richness and genotypic interactions differ in different disturbance treatments? Finally (iv) Is phenotypic variation greater as genotypic richness increases?
    Methods We conducted a 2-year common garden experiment in which we manipulated genotype richness using eight genotypes planted under both intact and disturbed conditions in a wetland in Burlington, Vermont (44°27′23″N, 73°11′29″W). The experiment consisted of a randomized complete block design of three blocks, each containing 20 plots (0.5 m 2) per disturbed treatment. We calculated total plot biomass and partitioned the net biodiversity effect into three components: dominance effect, trait-dependent complementarity and trait-independent complementarity. We calculated the phenotypic variance for each different genotype richness treatment under the two disturbance treatments.
    Important findings Our results indicate that local genotypic richness does not increase total biomass production of the invasive grass P. arundinacea in either intact or disturbed treatments. However, genotypic interactions underlying the responses showed very different patterns in response to increasing genotypic richness. In the intact treatment, genotypic interactions resulted in the observed biomass being greater than the predicted biomass from monoculture plots (e.g., overyielding) and this was driven by facilitation. However, facilitation was reduced as genotypic richness increased. In the disturbed treatment, genotypic interactions resulted in underyielding with observed biomass being slightly less than expected from the performance of genotypes in monocultures; however, underyielding was reduced as genotypic richness increased. Thus, in both treatments, higher genotypic richness resulted in plot biomass nearing the additive biomass from individual monocultures. In general, higher genotypic richness buffered populations against interactions that would have reduced biomass and potentially spread. Phenotypic variance also had contrasting patterns in intact and disturbed treatments. In the intact treatment, phenotypic variance was low across all genotypic richness levels, while in the disturbed treatment, phenotypic variance estimates increased as genotypic richness increased. Thus, under the disturbed treatment, plots with higher genotypic richness had a greater potential response to selection. Therefore, limiting the introduction of new genotypes, even if existing genotypes of the invasive species are already present, should be considered a desirable management strategy to limit the invasive behavior of alien species.
    Conor M. Redmond, Jane C. Stout
    2018, 11 (1): 56-63.
    Abstract ( 288 )   PDF   Save
    Aims Invasive alien plants can greatly affect native communities and ecosystem processes but only a small fraction of alien plant species become invasive. Barriers to establishment and invasion include reproductive limitations. Clematis vitalba L. has been a popular horticultural species for the past century and is widely distributed and can be highly invasive. In Ireland, it is considered naturalized and potentially invasive. Despite this, little is known about its reproductive biology.
    Methods We carried out manipulative field experiments in Ireland and compared fruit and seed set from a number of pollination treatments, namely cross-pollination, geitonogamy, autogamy and natural pollination. We also recorded floral visitation to C. vitalba through a series of timed observations.
    Important findings We found that C. vitalba is capable of uniparental reproduction via geitonogamy and autonomous selfing, albeit at a reduced rate compared with outcrossing treatments. Clematis vitalba was visited by at least 10 native pollinator taxa, with hoverflies dominating visitation. Neither fruit set nor seed set in our study population was pollen limited. Given the lack of reproductive constraint, C. vitalba may easily spread in suitable habitats. This is of concern in Ireland, given its prevalence in some of the country's most floristically diverse regions.
    Teresa L. Clark, Basil V. Iannone III, Songlin Fei
    2018, 11 (1): 64-72.
    Abstract ( 180 )   PDF   Save
    Aim The ability to quantitatively measure the continuum of macroscale patterns of species invasion is a first step toward deeper understanding of their causal factors. We took advantage of two centuries worth of herbarium data, to evaluate a set of metrics to measure macroscale patterns, allowing cross-species comparisons of invasive expansion across large geographic areas.
    Methods We used herbarium specimens to reconstruct county-level invasion histories for two non-native plants (Alliaria petiolata and Lonicera japonica), with distinct spatiotemporal distribution patterns over the past two centuries. Using county centroids from species' initial occurrences, we quantified point pattern metrics from multiple disciplines (e.g. urban crime analysis, landscape ecology etc.) that are historically used at smaller spatial scales, to evaluate their ability to detect macroscale spatial diffusion and amount of directional expansion. Metrics were further assessed for their ease of use, data requirements, independence from other metrics and intuitiveness of interpretation.
    Important findings We identified four suitable metrics for distinguishing differences in spatial patterns: (i) standard distance, (ii) number of patches, (iii) Euclidean nearest neighbor summary class statistic coefficient of variation and (iv) mean center that when applied to county-level presence data allowed us to determine the directions by which distributions expanded and if distributions increased via outward expansion, infilling and/or jump dispersal events. These metrics when compared during the same invasion phase are capable of quantifying macroscale variability among species in their distributional and dispersal patterns. Being able to quantify differences among species in these patterns is important in understanding the drivers of species dispersal patterns. These metrics therefore represent a simple yet thorough toolset for achieving this goal.
    Lisette M. Bakker, Liesje Mommer, Jasper van Ruijven
    2018, 11 (1): 73-84.
    Abstract ( 213 )   PDF   Save
    Aims The positive relationship between plant biodiversity and community productivity is well established. However, our knowledge about the mechanisms underlying these positive biodiversity effects is still limited. One of the main hypotheses is that complementarity in resource uptake is responsible for the positive biodiversity effects: plant species differ in resource uptake strategy, which results in a more complete exploitation of the available resources in space and time when plant species are growing together. Recent studies suggest that functional diversity of the community, i.e. the diversity in functional characteristics ('traits') among species, rather than species richness per se, is important for positive biodiversity effects. However, experimental evidence for specific trait combinations underlying resource complementarity is scarce. As the root system is responsible for the uptake of nutrients and water, we hypothesize that diversity in root traits may underlie complementary resource use and contribute to the biodiversity effects.
    Methods In a common garden experiment, 16 grassland species were grown in monoculture, 4-species mixtures differing in root trait diversity and 16-species mixtures. The 4-species mixtures were designed to cover a gradient in average rooting depth. Above-ground biomass was cut after one growing season and used as a proxy for plant productivity to calculate biodiversity effects.
    Important findings Overall, plant mixtures showed a significant increase in biomass and complementarity effects, but this varied greatly between communities. However, diversity in root traits (measured in a separate greenhouse experiment and based on literature) could not explain this variation in complementarity effects. Instead, complementarity effects were strongly affected by the presence and competitive interactions of two particular species. The large variation in complementarity effects and significant effect of two species emphasizes the importance of community composition for positive biodiversity effects. Future research should focus on identifying the traits associated with the key role of particular species for complementarity effects. This may increase our understanding of the links between functional trait composition and biodiversity effects as well as the relative importance of resource complementarity and other underlying mechanisms for the positive biodiversity effects.
    Lingfeng Mao, Shengbin Chen, Jinlong Zhang, Guangsheng Zhou
    2018, 11 (1): 85-91.
    Abstract ( 219 )   PDF   Save
    Aims Several studies have shown that plant height changes along environmental gradients. However, altitudinal patterns of plant height across species are still unclear, especially in regions sensitive to climate change. As canopy height decreases dramatically near the tree line in alpine areas, we hypothesize that plant height across all species also decreases with increasing altitude, and distinct thresholds exist along this gradient.
    Methods Using a large dataset of maximum plant height and elevation range (400 to 6000 m a.s.l.) of 4295 angiosperms from the regional flora of the Tibetan Plateau, we regressed plant height for every 100 m belt against elevation to explore the relationships. To identify the approximate boundaries where dramatic changes in plant height occurs for herbaceous plants, shrubs, trees, woody plants and all angiosperms, we used piecewise linear regression. Phylogenetically independent contrast was used to test the potential evolutionary influences on altitudinal patterns at the family level.
    Important findings Results showed that for herbaceous plants, shrubs, trees, woody plants and all angiosperms, plant height decreases significantly as altitude increases. In addition, we found that altitude, a proxy for many environmental factors, had obvious thresholds (breakpoints) dictating patterns of plant height. The results of phylogenetically independent contrast also emphasized the importance of evolutionary history in determining the altitudinal patterns of plant height for some growth forms. Our results highlight the relative intense filtering effect of environmental factors in shaping patterns of functional traits and how this could vary for different ranges of environmental variables.
    Luis G. Quintanilla, Beatriz Pías
    2018, 11 (1): 92-102.
    Abstract ( 176 )   PDF   Save
    Aims Plants control leaf phenology to maximize annual photosynthetic product. Although ferns play an important ecological role in many habitats, especially forests, their phenology traits have been poorly studied. Here, we investigate the leaf phenology of two ferns of the forest understorey and analyse the relationship between the timing of leaf emergence and spore dispersal and the effect of between-year climatic variation.
    Methods We compared the leafing and sporing phenologies of two ferns with very large (>2 m), overwintering leaves: Culcita macrocarpa and Woodwardia radicans. We regularly monitored individuals of six populations in the northwestern Iberian Peninsula during a 3-year study. We studied eight phenology variables: leafing start date, leafing end date, leaf expansion time, number of new leaves per individual, between-individual synchrony, within-individual synchrony, percentage of fertile leaves and spore release date. We also determined leaf mass per area (LMA) and gathered data on air temperature and humidity.
    Important findings Both C. macrocarpa and W. radicans produce few leaves (~2 leaves individual-1 year-1), which expand simultaneously for a very long period (from midwinter to early summer), are retained for more than 1 year (37 and 19 months, respectively) and have relatively high LMAs. Such traits, together with large leaf size, have also been found in seed plants from the forest understorey and represent adaptations to this light-limited environment. Spores of both study ferns are simultaneously released in late winter, with little between-year variation caused by differences in air humidity. This remarkable similarity between species suggests that the convergence in timing of leaf emergence favours the convergence in timing of spore dispersal.
    Dan Gafta, Anamaria Roman, Tudor M. Ursu
    2018, 11 (1): 103-113.
    Abstract ( 197 )   PDF   Save
    Aims Are there trends of increasing/decreasing dispersion of single, categorical traits related to early/late-successional species between stages of community development? If yes, are these trends dependent on species pool extension and habitat scale? Is there a consistent reduction in single trait convergence or divergence in any seral stage when scaling down from ecological to local species pool?
    Methods Presence of all vascular species rooted within plots of 5 × 5 m was recorded in assemblages of exposed mining spoils (EMS) and heathlands (HTL), which form a chronosequence on two abandoned ore tailing heaps located close to each other in the south-eastern Carpathians (Romania). Fifteen nominal, trait attributes of plant species co-occurring in the two seral assemblages were collected from available databases and subsequently classified as either successionally 'pioneer' or 'mature'. The strength of single trait convergence or divergence was estimated by comparison with null plant assemblages at patch type (meta-community) level by reference to the ecological or local species pool, and at community level.
    Important findings At patch type level, all pioneer and mature trait attributes (apart from short life span), with significant variation between the two seral stages, increased and, respectively, decreased in dispersion irrespective of species pool extension. However, these trends were more conspicuous when using the ecological species pool, very likely due to relaxation in abiotic filtering and dispersal limitation. At community level, no consistent trends were observed between EMS and HTL assemblages, probably because most trait attributes were sorted by microenvironmental filters displaying high variation, like topography or habitat patch geometry. In both seral stages, there was a general weakening of trait convergence or divergence at patch type level when scaling down from the ecological to the local species pool, which was due to niche space contraction. At community level, there was a trend of rise in dispersion of pioneer attributes along the observed chronosequence, presumably imputable to increasing competition for light and underground water, but an opposite trend of dispersion drop in mature attributes was not so evident. Based on these findings, we proposed two rules of thumb concerning the expected changes in dispersion of trait attributes at patch level along successions and between levels of species pool extension. In conclusion, trends in the successional dynamics of pioneer and mature trait dispersion are clearly detectable at meta-community level, especially by reference to the ecological species pool. Habitat scale and species pool extension are key factors to consider and report when estimating the magnitude of single trait dispersion.
    Adriana E. Olthoff, Cristina Gómez, Josu G. Alday, Carolina Martínez-Ruiz
    2018, 11 (1): 114-122.
    Abstract ( 216 )   PDF   Save
    Aims Forest vegetation variability may be explained by the complex interplay among several spatial structuring factors, including climate and topography. We modelled the spatial variability of forest vegetation assemblages and significant environmental variables along a complex environmental gradient or coenocline to produce a detailed cartographic database portraying the distribution of forests along it.
    Methods We combined an analysis of ordination coenoclines with kriging over 772 field data plots from the third Spanish National Forest Inventory in an Atlantic–Mediterranean transitional area (northern Spain).
    Important findings The best fitted empirical semivariogram revealed a strong spatial structure of forest species composition along the complex environmental gradient considered (the climatic–topographic gradient from north to south). The steady and gradual increase of semivariance with a marked lag distance indicates a gradual turnover of forest assemblages according to the climatic–topographic variations (regional or local). Two changes in the slope of the semivariogram suggest the existence of two different scales of spatial variation. The interpolation map by Kriging of forest vegetation assemblages along the main coenocline shows a clear spatial distribution pattern of trees and shrubs in accordance with the spatial variation of significant environmental variables. We concluded that the multivariate geostatistical approach is a suitable technique for spatial analysis of forest systems employing data from national forest inventories based on a regular network of field plots. The development of an assortment of maps describing changes in vegetation assemblages and variation in environmental variables is expected to be a suitable tool for an integrated forest management and planning.
    Clementina González, Anai Alvarez-Baños, Eduardo Cuevas
    2018, 11 (1): 123-135.
    Abstract ( 184 )   PDF   Save
    Aims The evolution of the outstanding variation of reproductive systems in angiosperms has been considered an important driver of lineage diversification. Closely related hermaphroditic and dioecious species with biotic pollination provide the opportunity to study and compare traits related to pollinator attraction and their consequences on reproductive components. A higher predictability of pollination syndromes is expected in dioecious species, which are dependent on pollinators, than in self-compatible hermaphroditic taxa. Dioecious species may suffer pollen limitation depending on the quality of floral rewards and the kind and abundance of pollinators, whereas no pollen limitation is expected in hermaphroditic species with autonomous self-pollination. Additionally, in the absence of pollen limitation, more or better seeds are expected in dioecious species, according to the sexual specialization hypothesis.
    Methods In natural populations of the hermaphroditic Fuchsia fulgens and Fuchsia arborescens and dioecious Fuchsia parviflora and Fuchsia obconica, all endemic to Mexico, we first described flower phenology, flower production and longevity and nectar volume and concentration. Then, we evaluated the correspondence between floral visitors and pollination syndromes. In hermaphrodite plants, we determined the level of herkogamy and the potential for autonomous self-pollination. Finally, we evaluated the effect of pollen limitation on fruit set and seed number and assessed seed germination for all species.
    Important findings In contrast to our prediction, dioecious species did not show a higher correspondence between pollination syndromes and floral visitors than did hermaphrodites; however, male flowers exhibited a higher correspondence than female flowers. No pollen limitation was detected in dioecious species, for which visitation rate did not differ between male and female flowers. The hermaphroditic F. fulgens showed pollen limitation for seed number, despite the presence of autonomous selfing. Fruit set from autonomous pollination was higher in F. arborescens, which showed a lower level of herkogamy compared with F. fulgens. Finally, dioecious species produced fewer but heavier seeds compared with hermaphrodite species. Although Fuchsia is classified as an outcrossing genus, both hermaphroditic species showed autonomous self-pollination. The heavier but lower number of seeds per fruit in dioecious species may be related to the more efficient resource allocation expected from sexual specialization. This could play an important role in the evolution of dioecy; however, a comparative phylogenetic approach is required to confirm this hypothesis.
    Amaranta Arellano-Rivas, J. Arturo De-Nova, Miguel A. Munguía-Rosas
    2018, 11 (1): 136-146.
    Abstract ( 198 )   PDF   Save
    Aims It is known that taxonomic diversity can be predicted by the spatial configuration of the habitat, in particular by its area and degree of isolation. However, taxonomic diversity is a poor predictor of ecosystem functioning. While functional diversity is strongly linked to the functionality and stability of ecosystems, little is known about how changes in the spatial configuration of the habitat affect functional diversity. In this study, we evaluated whether the spatial configuration of forest patches predicts the functional diversity of plants in a fragmented forest.
    Methods Five functional leaf traits (leaf dry matter content, leaf punch force, specific leaf area, leaf size and leaf thickness) were measured for 23 dominant plant species in 20 forest patches in a naturally fragmented forest on the Yucatan Peninsula. Abundance-weighted multivariate and individual trait metrics of functional diversity were calculated and correlated with size, degree of isolation and the shape of forest patches.
    Important findings Patch shape was negatively correlated with multivariate and individual trait (leaf dry matter content and leaf size) metrics of functional diversity. Patch isolation measures were also negatively correlated with individual trait (leaf dry matter content, leaf punch force and leaf size) metrics of functional diversity. In other words, greater patch shape irregularity and isolation degree impoverish plant functional variability. This is the first report of the negative effects of patch shape irregularity and isolation on the functional diversity of plant communities in a forest that has been fragmented for a long time.
    Marco A. Molina-Montenegro, Alejandro del Pozo, Ernesto Gianoli
    2018, 11 (1): 147-157.
    Abstract ( 201 )   PDF   Save
    Aims Successful invasive plants are often assumed to display significant levels of phenotypic plasticity. Three possible strategies by which phenotypic plasticity may allow invasive plant species to thrive in changing environments have been suggested: (i) via plasticity in morphological or physiological traits, invasive plants are able to maintain a higher fitness than native plants in a range of environments, including stressful or low-resource habitats: a 'Jack-of-all-trades' strategy; (ii) phenotypic plasticity allows the invader to better exploit resources available in low stress or favorable habitats, showing higher fitness than native ones: a 'Master-of-some' strategy and (iii) a combination of these abilities, the 'Jack-and-Master' strategy.
    Methods We evaluated these strategies in the successful invader Taraxacum officinale in a controlled experiment mimicking natural environmental gradients. We set up three environmental gradients consisting of factorial arrays of two levels of temperature/light, temperature/water and light/water, respectively. We compared several ecophysiological traits, as well as the reaction norm in fitness-related traits, in both T. officinale and the closely related native Hypochaeris thrincioides subjected to these environmental scenarios.
    Important findings Overall, T. officinale showed significantly greater accumulation of biomass and higher survival than the native H. thrincioides, with this difference being more pronounced toward both ends of each gradient. T. officinale also showed significantly higher plasticity than its native counterpart in several ecophysiological traits. Therefore, T. officinale exhibits a Jack-and-Master strategy as it is able to maintain higher biomass and survival in unfavorable conditions, as well as to increase fitness when conditions are favorable. We suggest that this strategy is partly based on ecophysiological responses to the environment, and that it may contribute to explaining the successful invasion of T. officinale across different habitats.
    Honglin Li, Kailiang Yu, Danghui Xu, Wei Li, Dorjeeh Tondrob, Guozhen Du
    2018, 11 (1): 158-167.
    Abstract ( 167 )   PDF   Save
    Aims The mature meadows (MMs) and the swamp meadows (SMs) are the two most important ecosystems in the eastern Tibetan Plateau, China. Besides their substantial differences in terms of soil water conditions and thereby the soil oxygen and nutrients, however, little is known about the differences in community composition, structure, traits and productivity between these two meadows. We particularly ask whether light availability mediated by physical structure heterogeneity is a key determinant of the difference in community composition and productivity between these two meadows.
    Methods We examined the community structure, composition, aboveground net primary productivity (ANPP), light availability in understory and the community-weighted means (CWMs) for leaf morphological and physiological traits in 12 random plots (5 m × 5 m) for each of the studied habitats.
    Important findings The results showed that plant community in the MM had higher variation in both vertical and horizontal structure and thus had more light availability in the understory. The MM had higher species richness and greater ANPP than the SM. The CWMs of leaf morphological and physiological traits for species in the MM featured a fast-growing strategy (i.e. higher height, leaf area and net photosynthesis rate and lower nitrogen:phosphorus ratio), in contrast to those in the SM. We also found that there were significant correlations between the CWM of traits and the ANPP, indicating that some key traits in these habitats have linked to community productivity. Our study also suggests that the heterogeneity in the community structure, which affects light availability in the understory, may play an important role in determining the community composition and productivity. In conclusion, our study revealed significant differences in community structure, composition and traits between the MM and the SM, and the light availability that related closely to community structure is the key factor to determine the composition and productivity of the community of these two habitats.
IF: 1.780
5-year IF: 2.674
Wen-Hao Zhang
Bernhard Schmid
CN 10-1172/Q
ISSN 1752-9921(print)
ISSN 1752-993X(online)