Generalized linear mixed models (GLMMs) have been widely used in contemporary ecology studies. However, determination of the relative importance of collinear predictors (i.e. fixed effects) to response variables is one of the challenges in GLMMs. Here, we developed a novel R package, glmm.hp, to decompose marginal R² explained by fixed effects in GLMMs. The algorithm of glmm.hp is based on the recently proposed approach ‘average shared variance’ i.e. used for multivariate analysis. We explained the principle and demonstrated the use of this package by simulated dataset. The output of glmm.hp shows individual marginal R²s that can be used to evaluate the relative importance of predictors, which sums up to the overall marginal R². Overall, we believe the glmm.hp package will be helpful in the interpretation of GLMM outcomes.

Plants growing in nutrient-rich environment are predicted to be less defended than conspecifics under nutrient limitation. However, less is known about the effects of nutrient levels on tolerance and induced resistance, and whether the effects differ between native and introduced populations of invasive plants. We performed a greenhouse experiment with introduced (the USA) and native (Argentina) genotypes of Alternanthera philoxeroides in order to study the effects of soil nitrogen levels on plant growth, constitutive and herbivore (Agasicles hygrophila)-induced chemical defense, and herbivory tolerance. We measured total biomass, elongation rate (as proxy of growth rate), carbon and nitrogen, and the concentration of triterpenoid saponins (defensive chemicals) in leaves and roots. Constitutive resistance (+33% higher leaf triterpenoid saponins in control treatment at low nitrogen level) and tolerance [less decreased total biomass after herbivory treatment (−24% and −15% for high and low nitrogen levels)] were favored at lower nitrogen level, while induced resistance was favored at higher nitrogen level (+24% increased leaf triterpenoid saponins after herbivory treatment at high nitrogen level). Constitutive resistance and tolerance exhibited trade-offs with growth rate, while induced resistance positively correlated with growth rate. Additionally, the introduced genotypes had −6% lower content of leaf carbon in the presence of herbivores than the native genotypes at low nitrogen level, but such difference was absent at high nitrogen level. Our results indicate that soil nitrogen levels influence the preference of different defensive strategies of plant, and interweave with herbivory to determine the performance of introduced genotypes.

Previous studies showed that moss stoichiometric characteristics were influenced by moss patch size, shrubs and the environment in the desert. The study of moss stoichiometry in different spatial distribution areas is crucial for an understanding of growth and adaptation strategy of the mosses. In this study, the dominant moss (Syntrichia caninervis) of biological soil crusts and soil under the moss patches in the Gurbantunggut Desert were selected to determine their stoichiometry in different dunes and sites. Moss stoichiometry and soil available nutrients were significantly influenced by different distribution areas except for moss C. The N_aboveground vs. N_belowground' P_aboveground vs. P_belowground and K_aboveground vs. K_belowground scaling exponents of moss were 0.251, 0.389 and 0.442, respectively. The N vs. P scaling exponents were 0.71, 0.84 in above- and below-ground parts of moss. Moss stoichiometry was disproportionately distributed in the above-ground and below-ground parts. Moreover, moss N, P and K elements were influenced by mean annual precipitation (MAP), longitude and soil nutrients. The nutrients of moss were affected by spatial distribution, mean annual temperature (MAT), MAP and soil nutrients. The growth of moss was limited by N element in the temperate desert. This study provides the stoichiometric characteristics of C, N, P and K of moss at different spatial scales and explores their relationships with environmental variables, which can help understand nutrient patterns and utilization strategy of N, P and K, and their potential responses to global climate changes in desert.

Fine-root decomposition is a critical process regulating ecosystem carbon cycles and affecting nutrient cycling and soil fertility. However, whether interaction between warming and grazing affects fine-root decomposition is still under-researched in natural grasslands. A two-factorial experiment with asymmetric warming (i.e. daytime vs. nighttime and growing season vs. nongrowing season) and moderate grazing (i.e. about average 50% forage utilization rate) was conducted to explore whether warming and grazing affect fine-root decomposition and loss of nutrients during a 2-year decomposition period in an alpine meadow on the Tibetan Plateau. Both warming and grazing facilitated carbon cycling through increase in fine-root decomposition, and influenced element cycling which varies among elements. The effects of warming and grazing on fine-root decomposition and loss of nutrients were additive. Both warming and grazing significantly increased cumulative percentage mass loss and total organic carbon loss of fine roots during the 2-year experiment. Only warming with grazing treatment reduced percentage nitrogen loss, whereas warming, regardless of grazing, decreased percentage phosphorus loss. Warming and grazing alone increased percentage loss of potassium, sodium, calcium and magnesium compared with control. There were no interactions between warming and grazing on fine-root decomposition and loss of nutrients. There was greater temperature sensitivity of decreased phosphorus loss than that of decreased nitrogen loss. Different temperature sensitivities of percentage loss of nutrients from fine-root decomposition would alter ratios of the available nutrients in soils, and may further affect ecosystem structure and functions in future warming.

Given the current scenario of climate change and anthropogenic impacts, spatial predictions of biodiversity are fundamental to support conservation and restoration actions. Here, we compared different stacked species distribution models (S-SDMs) to forest inventories to assess if S-SDMs capture emerging properties and geographic patterns of species richness and composition of local communities in a biodiversity hotspot. We generated SDMs for 1499 tree species sampled in 151 sites across the Atlantic Forest. We applied four model stacking approaches to reconstruct the plant communities: binary SDMs (bS-SDMs), binary SDMs cropped by minimum convex polygons (bS-SDMs-CROP), stacked SDMs constrained by the observed species richness (cS-SDMs) and minimum convex polygons of species occurrences (MCPs). We compared the stacking methods with local communities in terms of species richness, composition, community prediction metrics and components of beta diversity—nestedness and turnover. S-SDMs captured general patterns, with bS-SDMs-CROP being the most parsimonious approach. Species composition differed between local communities and all stacking methods, in which bS-SDMs, bS-SDMs-CROP and MCPs followed a nested pattern, whereas species turnover was most important in cS-SDMs. S-SDMs varied in terms of performance, omission and commission errors, leading to a misprediction of some vulnerable, endangered and critically endangered species. Despite differing from forest inventory data, S-SDMs captured part of the variation from local communities, representing the potential species pool. Our results support the use of S-SDMs to endorse biodiversity synthesis and conservation planning at coarse scales and warn of potential misprediction at local scales in megadiverse regions.

Vegetation green-up is occurring earlier due to climate warming across the Northern Hemisphere, with substantial infuences on ecosystems. However, it is unclear whether temperature responses differ among various green-up stages. Using high-temporal-resolution satellite data of vegetation greenness and averaging over northern vegetation (30–75° N), we found the negative interannual partial correlation between the middle green-up stage timing (50% greenness increase in spring–summer) and temperature (R_P = −0.73) was stronger than those for the onset (15% increase, R_P = −0.65) and end (90% increase, R_P = −0.52) of green-up during 2000–2022. Spatially, at high latitudes, the middle green-up stage showed stronger temperature responses than the onset, associated with greater low-temperature constraints and stronger control of snowmelt on green-up onset as well as greater spring frost risk. At middle latitudes, correlations with temperature were similar between the onset and middle stages of green-up, except for grasslands of the Mongolian Plateau and interior western USA, where correlations with temperature were weaker for the middle stage due to water limitation. In contrast, the end of the green-up showed weaker temperature responses than the middle due to insuffcient water and high climatic temperature during the end of the green-up in most of the study region, except for cold regions in the interior western USA, western Russia and the Tibetan Plateau, where temperature was still a main driver during end of green-up. Our fndings underscore the differences in temperature responses among green-up stages, which alters the temporal alignment between plants and environmental resources.

Leaf size varies conspicuously within and among species under different environments. However, it is unclear how leaf size would change with elevation, whether there is a general elevational pattern, and what determines the altitudinal variation of leaf size. We thus aimed to address these questions by focusing on the broad-leaved herbaceous species at high altitudes on the northeastern Qinghai-Tibetan Plateau. We measured the leaf size, leaf length, leaf width and leaf mass per area for 39 broad-leaved herbaceous species inhabited in the open areas along two mountain slopes from 3200 to 4400 m at the Lenglongling and the Daban Mountain, the northeastern Qinghai-Tibetan Plateau. We analyzed the altitudinal patterns in leaf size in relation to leaf inclination and leaf surface features, and applied a leaf energy balance model to discuss the underlying mechanisms. Leaf size decreased significantly at higher altitudes. The altitudinal reduction of leaf size was mainly attributed to the reduction of leaf length, and differed in different species, and in leaves with different inclination and leaf surface features. A leaf energy balance model with local environmental measurements demonstrates that leaf temperature tracks air temperature more closely in small than in large leaves, and that the leaf-size impact is stronger at higher latitudes. Based on the observational findings, we propose that the distribution upper-limit for broad-leaved herbaceous species would be at an elevation of about 5400 m on the northeastern Qinghai-Tibetan Plateau.

Caryota obtusa of Arecaceae is a fascinating palm tree native to southwestern China, India, Myanmar, Thailand, Laos and Vietnam. It is an economically important and threatened species and appears as a canopy dominant in some karst areas in Yunnan. We aim to clarify the forest structure, species diversity, population status and regeneration dynamics of C. obtusa in the karst forest ecosystem of Yunnan, China. We established 56 vegetation plots dominated by C. obtusa in 10 counties of southern Yunnan. Based on the plot data, we analyzed the community stratification, floristic composition and C. obtusa’s population structure. We used questionnaires to interview local people and recorded the human activity history in C. obtusa-dominated forests. Caryota obtusa palm forests were distributed on limestone mountain slopes and gullies. There were seven forest community types. The stratification of each community included arborous layer, shrub layer and understory. The communities had rich species composition. For all the plots as a whole of each community type, Shannon–Wiener diversity index of either woody or herbaceous species ranged from 2.1 to 3.8. The diameter at breast height (DBH)-class frequency distribution of C. obtusa was a multimodal type. The regeneration was sporadic and dependent on intermediate natural disturbances. In the current population structure, a number of C. obtusa trees with small DBHs consisted mainly of the forest communities with no or a slight degree of human disturbances. Intensive human activities terribly hindered recruitment of C. obtuse, followed by the medium intensity of human activities.

Many mosses and lichens thrive in high-elevation subalpine forests and even become dominant species on the forest floor. Although they play an irreplaceable ecological role in the forest, less is known about their eco-physiological status, and how their photosynthesis-related functional traits differ from those of co-occurring vascular plants. We determined the carbon, nitrogen and phosphorus concentrations and stoichiometric ratios, tissue mass per area, chlorophyll concentrations and photosynthetic light–response curves of three lichens, three mosses and four vascular plants in a subalpine forest in the eastern Tibetan Plateau of China. Trait values were compared among and within each group. The lichens possessed a higher nitrogen concentration than that of mosses. In addition, the two poikilohydric groups exhibited lower concentrations of nitrogen, phosphorus and chlorophyll, light-saturated assimilation rates and photosynthetic nutrient use efficiencies, and higher light compensation points than those of vascular plant leaves. Furthermore, variations in photosynthesis-related traits for lichen species reflect their different adaptation strategies to their corresponding environments. In contrast, the differences were weak among the three forest-floor mosses and the three herb species. These results demonstrate that the high abundance of understory lichens and mosses in the high-elevation subalpine forest cannot be explained by the photosynthesis-related traits.

Drought can affect the growth and soil enzyme activities of invasive alien plants (IAPs). It is imperative to evaluate the competitive advantage of IAPs compared with that of the native species and the activities of soil enzymes under drought. This study aimed to evaluate the competitive advantage of the IAP Amaranthus spinosus that originated from tropical America compared with the native Chinese species A. tricolor and the activities of soil enzymes under drought. A competitive co-culture of A. spinosus and A. tricolor was established using a planting basin experiment. The two species were treated with different levels of drought, i.e. (i) the control; (ii) a light level of drought and (iii) a heavy level of drought. The functional traits, osmotic adjustment and the activities of antioxidant enzymes of the two species, as well as soil pH and electrical conductivity, contents of soil microbial biomass carbon and the activities of soil enzymes were determined. The relative competition intensity and relative dominance of A. spinosus were greater than those of A. tricolor under drought. Drought may provide an advantage to the competitive advantage of A. spinosus. Soil water-soluble salt content and sucrose hydrolytic power of A. spinosus were greater than those of A. tricolor under drought. The ability of A. spinosus to grow in soil with higher levels of water-soluble salt contents and sucrose hydrolytic power under drought may aid in its acquisition and utilization of nutrients.

To compare current methods of pretreatment/determination for plant foliar pH, we proposed a method for long-period sample preservation with little interference with the stability of foliar pH. Four hundred leaf samples from 20 species were collected and four methods of pH determination were used: refrigerated (stored at 4 °C for 4 days), frozen (stored at −16 °C for 4 days), oven-dried and fresh green-leaf pH (control). To explore the effects of different leaf:water mixing ratio on the pH determination results, we measured oven-dried green-leaf pH by leaf:water volume ratio of 1:8 and mass ratio of 1:10, and measured frozen senesced-leaf pH by mass ratio of 1:10 and 1:15. The standard major axis regression was used to analyze the relationship and the conversion equation between the measured pH with different methods. Foliar pH of refrigerated and frozen green leaves did not significantly differ from that of fresh green-leaf, but drying always overrated fresh green-leaf pH. During the field sampling, cryopreservation with a portable refrigerator was an advisable choice to get a precise pH. For long-duration field sampling, freezing was the optimal choice, and refrigeration is the best choice for the short-time preservation. The different leaf:water mixing ratio significantly influenced the measured foliar pH. High dilution reduced the proton concentration and increased the measured pH. Our findings provide the conversion relationships between the existing pretreatment and measurement methods, and establish a connection among pH determined by different methods. Our study can facilitate foliar pH measurement, thus contributing to understanding of this interesting plant functional trait.

Salt stress is a vital factor limiting nitrogen uptake and cotton growth in arid regions. The mechanisms underlying salt stress tolerance in cotton plants under high soil salinity have not been fully elucidated. Therefore, the aim of this study was to examine the proportion and mechanism of cotton nitrogen uptake under salt stress using the ¹⁵N isotope labeling technique. Cotton plants were grown in four undisturbed saline soils (1, 3, 6 and 9 dS m⁻¹), and the experiment was designed using the ENVIRO-GRO (E-G) model. The results showed that the dry matter of roots, stems and leaves of the cotton parts in slightly saline soil (C2, 3 dS m⁻¹) was not significant compared with the non-saline soil (C1, 1 dS m⁻¹). The cotton fruit grown in low-salinity soil (C2, 3 dS m⁻¹) had significantly higher dry matter than that grown in the other treatments, implying that cotton plants grown in 3 dS m⁻¹ soil have the best nitrogen uptake and salt tolerance. Cotton plants grown in weakly (C3, 6 dS m⁻¹) and moderately (C4, 9 dS m⁻¹) saline soils exhibited premature senescence. The distribution of total nitrogen and nitrate content in cotton was the best explanatory variable of total ¹⁵N recovery, of which cotton ¹⁵N recovery was between 26.1% and 47.2%, and soil ¹⁵N recovery was between 7.7% and 14.9%. Our findings provide guidance for further exploitation and utilization of saline soil resources and sustainable development of the agricultural soil ecosystem in arid regions.

Plant invasions can affect soil properties in the invaded habitat by altering the biotic and abiotic nature of soils through positive or negative plant–soil feedback. Litter decomposition from many invasive species enhanced soil nutrients, thereby decreasing native plant diversity and leading to further plant invasions. Here, we examined the impact of litter decomposition from an invasive plant (Sphagneticola trilobata) in a range of soils at varying depths on growth and physiology of its native congener (Sphagneticola calendulacea). We added litter from S. trilobata to each soil type at different depths (0, 2, 4 and 6 cm). Plants of S. calendulacea were grown in each treatment, and morphological and physiological parameters were measured at the end of the growing period. All soils treated with litter displayed increases in soil nutrients at depths of 2 and 4 cm; while most growth traits, leaf chlorophyll and leaf nitrogen of S. calendulacea decreased at the same soil depths. Therefore, litter decomposition from invasive S. trilobata resulted in a positive plant–soil feedback for soil nutrients, and a negative plant–soil feedback for growth in native S. calendulacea. Our findings also suggest that the effects of litter decomposition from an invasive plant on soils and native species can vary significantly depending on the soil depth at which the litter is deposited. Future studies should focus on plant–soil feedback for more native and invasive species in invaded habitats, and the effects of invasive litter in more soil types and at greater soil depths.

Invasive alien plants threaten biodiversity across the world. Erigeron canadensis (horseweed) is one of the most problematic agricultural weeds and represents a classic example of intercontinental invasion. Here, we studied the genetic diversity and population structure of invasive alien populations from the Jiangsu and Zhejiang Provinces in China and native populations from Alabama, in the USA. We used 10 polymorphic SSR loci to genotype 312 individuals from 5 native and 5 invasive populations to estimate the genetic diversity and structure. Invasive populations from Jiangsu and Zhejiang Provinces showed, on average, similar genetic diversity to native populations from Alabama, indicating no severe genetic bottlenecks during the invasion. STRUCTURE revealed that low population differentiation occurred, and that only two genetic groupings were detected in both native and invaded ranges. The high diversity observed in the invasive populations suggested multiple introductions and/or the introduction of genetically diverse propagules during initial colonization. Our study provides new insights toward understanding the invasion dynamics of this globally noxious weed in Eastern China. Preventing gene flow via seed dispersal between invasive and native populations should be examined to prevent the introduction and dispersal of herbicide-resistant individuals and inform management practices.

Climatic warming affects plant growth and physiology, yet how warming alters chemistry in invasive plants and indirectly affects herbivorous insects remains largely unknown. Here, we explored warming-induced changes in leaf chemistry of the invasive plant Alternanthera philoxeroides and its native congener Alternanthera sessilis, and further examined how these changes affected the performance of the herbivores, Cassida piperata and Spodoptera litura. We conducted a simulated warming experiment to address its effects on 13 leaf chemical traits of A. philoxeroides and A. sessilis. We measured growth and development time of two herbivores reared on plants from warming or ambient controls. Warming significantly affected leaf chemistry composition for both the invasive and native Alternanthera. Warming decreased nitrogen concentration in A. philoxeroides and increased total flavonoid and total phenol concentration in A. sessilis. The effects of warming on nutrients (i.e. fructose, sucrose, total soluble sugar and starch) varied with individual chemicals and plant species. Weight of C. piperata pupal and S. litura larval reared on warming-treated A. sessilis significantly decreased compared with non-warmed control, and a similar pattern was observed for weight of S. litura larval feeding on warming-treated A. philoxeroides. In addition, warming-treated A. sessilis significantly prolonged larval development time of S. litura. These results indicate that warming can directly affect the leaf chemistry in both invasive plant and its native congener, but these effects vary by species. Such differences in warming-induced changes in plant chemistry could indirectly affect herbivorous insects associated with the invasive and native plants.

glmm.hp is an R package designed to evaluate the relative importance of collinear predictors within generalized linear mixed models (GLMMs). Since its initial release in January 2022, it has been rapidly gained recognition and popularity among ecologists. However, the previous glmm.hp package was limited to work GLMMs derived exclusively from the lme4 and nlme packages. The latest glmm.hp package has extended its functions. It has integrated results obtained from the glmmTMB package, thus enabling it to handle zero-inflated generalized linear mixed models (ZIGLMMs) effectively. Furthermore, it has introduced the new functionalities of commonality analysis and hierarchical partitioning for multiple linear regression models by considering both unadjusted R₂ and adjusted R2 Related Articles | Metrics

The rapid uplift of the Qinghai-Tibet Plateau and its aridification has significantly affected the distribution and community structure of the plants in these regions. However, most of the studies have focussed on vascular plants, and it has been unclear whether bryophytes, which are haploid plants, had similar historical population dynamics to other vascular plants during the dramatic geological and climatic environment changes of the Quaternary. This study used Syntrichia caninervis Mitt as the research object and investigated its genetic variation, differentiation and population dynamic history in China. We genotyped 27 populations throughout the distributional range of S. caninervis using two chloroplast DNA regions and 19 nuclear microsatellite loci and supplemented these data with ecological niche modelling of the potential distribution areas from the last interglacial period. The results showed that genetic data consistently identified three clades: the Qinghai-Tibet Plateau, Pamir Plateau-TienShan and Central Asia. The genetic variation of Syntrichia caninervis mainly occurred within populations and in the populations within a specific region. However, there was a significant gene exchange between the different regions. S. caninervis may have expanded during the glacial period and shrank during the interglacial period. This study provides new evidence for the dynamic population history of drought-tolerant bryophytes in response to severe environmental changes during the Quaternary glacial and interglacial cycles.

Seed dormancy ensures seedling establishment in the favorable season in a seasonally changing environment. Korean pine (Pinus koraiensis Sieb. et Zucc.) seeds have morphophysiological dormancy after dispersal in autumn. A small fraction of seeds germinates in the first spring, but most seeds germinate in the second spring following dispersal. It is not clear how dormancy status changes and thus drives germination characteristic. Fresh Korean pine seeds were buried between litterfall and soil in Fenglin National Nature Reserves, Heilongjiang Province, northeastern China, in middle October 2018 and regularly exhumed. Field germination percentage, embryo growth, seed viability and laboratory germination percentage of exhumed seeds were determined. The physiological dormancy part of morphophysiological dormancy was gradually released during the first winter, but reinduced in the first summer following dispersal. The reinduced physiological dormancy was broken again in the second autumn and winter. The morphological dormancy part of morphophysiological dormancy was slowly released over the first summer but rapidly broken during the second early and middle autumn. In the second spring, Korean pine seeds completely escaped from morphophysiological dormancy. The physiological dormancy part of morphophysiological dormancy was completely released, but the morphological dormancy part was still maintained, leading to very low germination in the first spring in the field. Relief of morphophysiological dormancy enables a high percentage of seeds to germinate at relatively low temperature (alternating day/night temperature above 10/5 °C) in the second spring. Korean pine provides an example of the change in dormancy status of seeds with morphophysiological dormancy.

Invasive alien plants not only decrease riparian vegetation diversity but also alter wetland ecosystem carbon processes, especially when they displace the original vegetation. Invasive Canada goldenrod (Solidago canadensis L.) has colonized large areas of disturbed and undisturbed land in southeastern China, yet little is known regarding how it affects soil carbon cycling. To explore the response patterns of soil respiration following S. canadensis invasion and their driving mechanisms, an observational field study and a greenhouse experiment simulating invasion were performed. In the field study, soil respiration was measured weekly from 21th July 2018 to 15th December 2018. In the greenhouse experiment, soil, autotrophic and heterotrophic respiration were measured every 1st and 15th of the month from 15th July 2019 to 15th December 2019. Soil, autotrophic and heterotrophic respiration were measured using a closed-chamber system with the deep gauze collar root exclusion method. Solidago canadensis invasion appeared to decrease the total soil CO₂ emissions in both the field study and the greenhouse experiment. The suppressive effects on soil respiration may be attributed to S. canadensis invasion-induced alterations in the quality and quantity of available soil substrate, suggesting that S. canadensis invasion may impact soil carbon cycling via plant-released substrates and by competing for the soil available substrate with native plant and/or soil microbes. These results have substantial implications for estimations of the effects of invasive plants on belowground carbon dynamics and their contribution to the warming world.

There is an increasing likelihood that invasive plants are again exposed to their co-evolved specialist herbivores in the non-native range. However, whether there is a latitudinal pattern associated with the resistance of an invasive plant to its co-evolved herbivores and how soil microbes affect resistance has been little explored. We hypothesized that the resistance of invasive Solidago canadensis to its co-evolved insect herbivore Corythucha marmorata could increase with latitude, and that local rhizosphere microbes could facilitate invasive plants to become resistant to their co-evolved herbivores. We conducted a field survey and a greenhouse experiment to examine whether there was a latitudinal pattern in the abundance of C. marmorata and in the damage it caused to S. canadensis in China. We tested whether local rhizosphere microbes of invasive plants can promote the resistance of S. canadensis to C. marmorata herbivory. In the field survey, both density of C. marmorata and damage level of S. canadensis were positively correlated with latitude, and with S. canadensis plant growth, indicating a latitudinal pattern in the resistance of S. canadensis to C. marmorata. However, in the greenhouse experiment, S. canadensis from different latitudes did not suffer significantly from different levels of damage from C. marmorata. Additionally, the damage level of S. canadensis was lower when rhizosphere soil and rhizomes originated from field S. canadensis with same damage level than with different damage levels. This result indicates that local rhizosphere soil microbes promote the adaptation of S. canadensis to resistance of C. marmorata.

Knowledge concerning the processes involved in defining the boundaries between rainforests (fire-sensitive) and open formations (fire-tolerant) is essential to safeguarding biodiversity and ecosystem services, especially under climate change and increased anthropogenic pressure. Here, we investigated the main environmental factors involved in the co-occurrence of forest islands and humid grasslands located in a protected area in the Espinhaço Biosphere Reserve, southeastern Brazil. We used permanent plots to collect the soil variables (moisture and chemical properties) in the forest islands. For sampling in wet grasslands, we installed four lines of 30 m from the edge of the islands in different directions. Subsequently, we delimited three points on each line10 m apart, totaling 12 points per area. We also surveyed the vegetation cover before and after prescribed burns. The environmental variables were subjected to tests of means and principal component analysis. We observed higher values of potassium, sum of bases, cation exchange capacity and organic matter in soils from forest islands than in wet grasslands. Therefore, the boundaries’ definition between the two vegetation types appeared to be primarily related to soil fertility and moisture gradients. After prescribed burning of the areas, no regeneration of arboreal individuals was detected near the edges of the islands. Therefore, our results suggest that forest islands are unable to expand due to well-defined edapho-climatic conditions. Thus, these environments should be a target focus for designing public conservation policies because they increase the complexity of the landscape of Campos Rupestres vegetation (mountain rocky grasslands).

Global changes have altered the distribution pattern of the plant communities, including invasive species. Anthropogenic contamination may reduce native plant resistance to the invasive species. Thus, the focus of the current review is on the contaminant biogeochemical behavior among native plants, invasive species and the soil within the plant–soil ecosystem to improve our understanding of the interactions between invasive plants and environmental stressors. Our studies together with synthesis of the literature showed that (i) the impacts of invasive species on environmental stress were heterogeneous, (ii) the size of the impact was variable and (iii) the influence types were multidirectional even within the same impact type. However, invasive plants showed self-protective mechanisms when exposed to heavy metals (HMs) and provided either positive or negative influence on the bioavailability and toxicity of HMs. On the other hand, HMs may favor plant invasion due to the widespread higher tolerance of invasive plants to HMs together with the ‘escape behavior’ of native plants when exposed to toxic HM pollution. However, there has been no consensus on whether elemental compositions of invasive plants are different from the natives in the polluted regions. A quantitative research comparing plant, litter and soil contaminant contents between native plants and the invaders in a global context is an indispensable research focus in the future.

Accelerated global warming in the late 20th century led to frequent forest-decline events in the Northern Hemisphere and increased the complexity of the relationships between tree growth and climate factors. However, few studies have explored the heterogeneity of responses of tree growth to climate factors in different regions of the Northern Hemisphere before and after accelerated warming. In this study, a total of 229 temperature-sensitive tree-ring width chronologies from nine regions on three continents in the Northern Hemisphere were used in the data analysis performed herein. A bootstrapped correlation analysis method was used to investigate whether the tree growth-climate response changed significantly in different regions between the periods before and after rapid warming. Probability density functions and piecewise linear fitting were used to study the fluctuation characteristics of the tree-ring width indices before and after rapid warming. At the end of the 20th century (from 1977 to 2000), rapid warming significantly promoted the radial growth of trees in different regions of the Northern Hemisphere, but tree radial growth was heterogeneous among the different regions from 1950 to 2000. After 1976, except in central North America and northern Europe, the correlation between tree growth and temperature increased significantly in the Northern Hemisphere, especially in Asia. From 1977 to 2000, tree-ring index and temperature divergences were observed in nine regions with a divergence of 2–5 years. From 1950 to 2000, tree growth tracked better average temperature variability in the Northern Hemisphere than regional temperature.

Current plant diversity can influence exotic plant invasion, but it is unclear whether there is a legacy effect of plant diversity on exotic plant invasion. As plant diversity can affect soil microbial communities and physio-chemical properties, which may cascade to impact subsequent exotic plant growth, we hypothesize that the soil legacy effect of plant diversity can influence exotic plant invasion. We conducted a plant–soil feedback experiment. In the conditioning phase, we trained soils by monocultures of 12 plant species from three functional groups (4 grasses, 3 legumes and 5 forbs) and mixtures of 8 randomly selected species with all three functional groups from this 12-species pool. In the test phase, we grew the invasive plant Bidens pilosa with a co-occurring native grass (Arthraxon hispidus), with a co-occurring native forb (Pterocypsela indica) or with both in each type of the conditioned soils. The performance of B. pilosa relative to its native competitors varied depending on the functional type of both conditioning plant species in the conditioning phase and competing plant species in the test phase. Diversity of the conditioning plants did not influence the growth difference between B. pilosa and its native competitors. However, increasing diversity of the competing plant species reduced the performance of B. pilosa relative to its native competitors. Our results suggest that current plant diversity can reduce exotic plant invasion through increasing growth inequality between invasive and native plants, but the soil legacy effect of plant diversity may have little impact on exotic plant invasion.

Arbuscular mycorrhizal fungi (AMF) can increase host plant nutrient uptake via their mycelium, thus promoting plant growth. AMF have always been associated with successful invasion of most exotic plant species. However, knowledge regarding how AMF affect the success of plant invasion remains limited. Exotic Ambrosia artemisiifolia is an invasive and mycorrhizal plant species. A long-term field experiment was conducted to examine the differences in AMF diversity and composition in the roots of A. artemisiifolia and Setaria viridis subjected to interspecific competition during growth. A greenhouse experiment was also performed to test the effect of Funneliformis mosseae on the growth of these two species. Ambrosia artemisiifolia invasion caused AMF diversity to change in native S. viridis roots. Meanwhile, the relative abundance of F. mosseae was significantly higher in the roots of A. artemisiifolia than in those of S. viridis. The higher AMF colonization rate in the exotic species (A. artemisiifolia) than in the native species (S. viridis) was found in both the field and greenhouse experiments. The greenhouse experiment possibly provided that AMF advantaged to the growth of A. artemisiifolia, by influencing its photosynthetic capacity as well as its phosphorus and potassium absorption. These observations highlight the important relationship of AMF with the successful invasion of A. artemisiifolia.

Understanding large-scale patterns of biodiversity and their drivers remains central in ecology. Many hypotheses have been proposed, including hydrothermal dynamic hypothesis, tropical niche conservatism hypothesis, Janzen’s hypothesis and a combination model containing energy, water, seasonality and habitat heterogeneity. Yet, their relative contributions to groups with different lifeforms and range sizes remain controversial, which have limited our ability to understand the general mechanisms underlying species richness patterns. Here we evaluated how lifeforms and species range sizes influenced the relative contributions of these three hypotheses to species richness patterns of a tropical family Moraceae. The distribution data of Moraceae species at a spatial resolution of 50 km × 50 km and their lifeforms (i.e. shrubs, small trees and large trees) were compiled. The species richness patterns were estimated for the entire family, different life forms and species with different range sizes separately. The effects of environmental variables on species richness were analyzed, and relative contributions of different hypotheses were evaluated across life forms and species range size groups. The species richness patterns were consistent across different species groups and the species richness was the highest in Sichuan, Guangzhou and Hainan provinces, making these provinces the hotspots of this family. Climate seasonality is the primary factor in determining richness variation of Moraceae. The best combination model gave the largest explanatory power for Moraceae species richness across each group of range size and life forms followed by the hydrothermal dynamic hypothesis, Janzen’s hypothesis and tropical niche conservatism hypothesis. All these models has a large shared effects but a low independent effect (< 5%), except rare species. These findings suggest unique patterns and mechanisms underlying rare species richness and provide a theoretical basis for protection of the Moraceae species in China.

Shifts in the realized niches of exotic species may play an important role in their invasion. Galinsoga quadriradiata has invaded China widely and occupied many climate zones that are different from its native range. We addressed the climatic niche shift of G. quadriradiata and evaluated how this could contribute to its invasion in China. We used the Maxent model to predict the potential distribution of G. quadriradiata using its native and invaded range occurrences and climatic variables. Principal component analysis was conducted to measure climatic niche shifts of G. quadriradiata during its invasion in China. The models revealed only 32.7% niche overlap between the native and invasive populations. The niche similarity of the two populations was significantly low (Schoener’s D = 0.093, P < 0.005), suggesting the occurrence of a niche shift. The envelop and center of the realized climatic niche in China has shifted to lower temperature and less precipitation compared to that in its native range. The majority of invaded areas in southern China are in the stabilizing zone, whereas the colonization and adaptation zones are predicted to be at the leading edge of G. quadriradiata invasion in northern China. This suggests that the regional distribution of G. quadriradiata may be in a quasi-equilibrium state, and that the species continues to invade environmentally suitable areas. Alterations in G. quadriradiata’s niche would help to explain why this species is so invasive in China.

Variations in plant traits are indicative of plant adaptations to forest environments, and studying their relationships with tree growth provides valuable insights into forest regeneration. The spatial arrangement of plant seeds within the forest litter or soil critically influences the variations of root-leaf traits, thereby affecting the adaptive strategies of emerging seedlings. However, our current understanding of the impacts of individual root-leaf traits on seedling growth in different relative position, and whether these traits together affect growth, remains limited. This study focuses on the dominant tree species, Castanopsis kawakamii, within the Sanming C. kawakamii Nature Reserve of China. The present experiment aimed to examine the variations in root-leaf traits of seedling, focus on the relative positions of seeds within different layers: beneath or above the litter layer, or within the bare soil layer (without litter). Our findings provided evidence supporting a coordinated relationship between root and leaf traits, wherein leaf traits varied in conjunction with root traits in the relative positions of seeds. Specifically, we observed that seedlings exhibited higher values for specific leaf area and average root diameter, while displaying lower root tissue density. The mixed model explained 86.1% of the variation in root-leaf traits, surpassing the variation explained by the relative positions. Furthermore, soil nitrogen acted as a mediator, regulating the relationship between seedling growth and root-leaf traits, specifically leaf dry matter content and root tissue density. Therefore, future studies should consider artificially manipulating tree species diversity based on root-leaf traits characteristics to promote forest recovery.

Expansion of global trade and acceleration of climate change dramatically promote plant invasions. As a result, a large number of habitats harbor multiple invasive plant species. However, patterns of invasive interactions and the drivers mediating their interactions remain unclear. In this greenhouse, potted plant study, we tested the impacts of 18 invasive plant species on the growth of target invader Erigeron canadensis which is dominant in central China. Neighboring invasive species belong to three functional groups (grass, forb and legume) and have different levels of relatedness to E. canadensis. Growth of E. canadensis’ strongly depended on the identity of neighboring invaders. Some neighboring invasive species suppressed growth of E. canadensis, others had no effect, while some promoted growth of E. canadensis. Through analyses of functional and phylogenetic similarities between the target species and neighboring invaders, we showed that two factors probably play roles in determining the relative responses of E. canadensis. Generally, E. canadensis responded negatively to invasive grasses and forbs, while it responded positively to invasive legumes. Furthermore, the negative responses to neighboring invasive grasses and forbs increased with increasing phylogenetic distance between the neighbors and E. canadensis. In contrast, the positive responses to invasive legumes did not depend on phylogenetic distance from E. canadensis. Our results suggest that successful invasion of E. canadensis probably depends on the identity of co-occurring invasive plant species. Interactions between E. canadensis and other invasive species should help managers select management priorities.

Plants are frequently exposed to adverse environments during their life span. Among them drought stress is one of the major threats to agricultural productivity. In order to survive in such unstable environment, plants have developed mechanisms through which they recognize the severity of the stress based on the incoming environmental stimuli. To combat the detrimental effects of drought, the plants have evolved various strategies to modulate their physio-hormonal attributes. These strategies that can be modulated by shade and microbes contribute to enhancing tolerance to drought and reducing yield loss. Plant hormones, such as abscisic acid, auxin and ethylene have a major role in the shade- and microbe-associated improvement of drought tolerance through their effects on various metabolic pathways. In this process, the CLAVATA3/EMBRYOSURROUNDING REGION-RELATED 25 peptide has a major role due to its effect on ABA synthesis as shown in our regulatory model.

The effect of exotic plants on Bacillus diversity in the rhizosphere and the role of Bacilli in exotic or native plant species remain poorly understood. Flaveria bidentis is an invasive grass in China. Setaria viridis is a native grass and occurs in areas invaded by F. bidentis. Our objectives were (i) to examine the differences in the Bacillus communities between F. bidentis and S. viridis rhizospheres soil, and (ii) to compare the effects of Bacilli from F. bidentis and S. viridis rhizospheres on the competitiveness of the invasive species. Flaveria bidentis monoculture, mixture of F. bidentis and S. viridis and S. viridis monoculture were designed in the field experiment. Bacillus diversity in their rhizosphere was analyzed using 16S rRNA. One of the dominant Bacilli in the rhizosphere soil of F. bidentis was selected to test its effect on the competitive growth of F. bidentis in a greenhouse experiment. Bacillus diversity differed in F. bidentis and S. viridis rhizosphere. Brevibacterium frigoritolerans was the dominant Bacilli in the rhizosphere of both F. bidentis and S. viridis; however, its relative abundance in the F. bidentis rhizosphere was much higher than that in the S. viridis rhizosphere. In addition, B. frigoritolerans in the F. bidentis rhizosphere enhanced the growth of the plant compared with that of S. viridis by improving the nitrogen and phosphorus levels. This study showed that F. bidentis invasion influenced Bacillus communities, especially B. frigoritolerans, which, in turn, facilitated F. bidentis growth by increasing the levels of available nitrogen and phosphorus.

Multiple elements are critical for plant growth and survival, community structure and vegetation function. Chemical diversity, defined as the ranges in element concentrations of plant species within communities, could provide essential insights into plant nutrient strategies and community assembly rules. However, little is known about the chemical diversity of multi-elements besides N and P, and current understanding of chemical diversity is largely based on aboveground plant traits. We investigated understory plant communities in forest swamps along a local soil chemical gradient and determined 11 major and trace elements in leaves and roots of dominant and subordinate plants. Using n-dimensional hypervolume, we examined the changes in leaf and root chemical diversity and their linkages with soil properties. Plant chemical diversity decreased significantly with soil Al, Mn, Mg and Zn concentrations, but showed no relationships with soil N, P, K, Na, and Fe concentrations, soil pH and C:N. These patterns also held after controlling for species richness and soil moisture. Furthermore, leaf and root chemical diversity was positively correlated and showed similar relationships with soil factors. Root chemical diversity was not significantly higher than leaf chemical diversity. Our results emphasized the important role of soil trace elements for plant chemical diversity along the local soil chemical gradient. Similar patterns and extent of leaf and root chemical diversity may indicate similar local-scale environmental constraint on aboveand belowground plant chemical diversity. These findings have important implications for plant community assembly and ecosystem functioning influenced by soil nutrient changes.

Spatiotemporal variations in plant-pollinator interactions drive floral evolution and shape the diversity of flowers in angiosperms. However, the potential role of plant-pollinator interactions in driving floral differentiation across flowering times within a population has not been documented. In this study, we aimed to quantify the variations in pollinator-mediated selection of floral traits across different flowering times of Primula sikkimensis (an entomophilous plant) in two natural populations. The results demonstrated that plants were shorter and produced fewer flowers with larger sizes in the early flowering time than in the late flowering time. In early flowering time, pollinator types were fewer and visitation frequency was lower than in late flowering time, resulting in lower female fitness. Pollinator-mediated selection of floral traits varied with flowering time, and more floral traits received pollinator-mediated selection during early flowering time. These results highlight that temporal variation in plant-pollinator interactions may have a potential role in driving floral diversification within the population.

Phylosymbiosis, the congruence of microbiome composition with host phylogeny, is a valuable framework for investigating plant–microbe associations and their evolutionary ecology. This review assesses the prevalence of phylosymbiosis across the plant kingdom, elucidates the fundamental ecological and evolutionary processes contributing to its occurrence based on previous research and explores commonly used methods for identifying phylosymbiosis. We find that the presence of phylosymbiosis may be influenced by both phylogenetic distance and the taxonomic level at which host plants are examined, with the strength of associations potentially decreasing as the taxonomic scale becomes finer. Notably, the endophytic microbiome exhibits a stronger phylosymbiosis signal compared with the epiphytic or rhizosphere-associated microbiomes. Microorganisms such as fungi and bacteria can yield highly variable evidence for phylosymbiosis due to differences in colonization, transmission or functional characteristics. We also outline how the four community assembly processes (dispersal, selection, diversification and drift) contribute to the establishment and maintenance of host–microbe phylosymbiosis. Furthermore, we highlight the diversity of methods employed to detect phylosymbiosis, which involves three key processes: constructing host phylogenies, assessing microbial data and statistically evaluating the correlation between host phylogeny and microbial composition. Remarkably different methodologies across studies make comparisons between findings challenging. To advance our understanding, future research is expected to explore phylosymbiosis at lower taxonomic levels and investigate different microbial communities coexisting synergistically within the same host. Understanding the relative importance of community assembly processes in driving phylosymbiosis will be critical for gaining deeper insights into the ecology and evolution of host–microbe interactions.

Senesced-leaf nutrient concentrations vary significantly among coexisting plant species reflecting different leaf nutrient use strategies. However, interspecific variation in senesced-leaf nutrients and its driving factors are not well understood. Here, we aimed to determine interspecific variation and its driving factors in senesced-leaf nutrients. We explored interspecific variation in carbon (C), nitrogen (N) and phosphorus (P) concentrations in newly fallen leaves of 46 coexisting temperate deciduous woody species across the Maoershan Forest Ecosystem Research Station, Northeast China. The relative importance of 10 biotic factors (i.e. mycorrhiza type, N-fixing type, growth form, shade tolerance, laminar texture, coloring degree, coloring type, peak leaf-coloration date, peak leaf-fall date and end leaf-fall date) was quantified with the random forest model. N and P concentrations varied 4- and 9-fold among species, respectively. The high mean N (15.38 mg g⁻¹) and P (1.24 mg g⁻¹) concentrations suggested a weak N and P limitation in the studied forest. Functional groups had only significant effects on specific nutrients and their ratios. P concentration and N:P were negatively correlated with peak and end leaf-fall dates for the ectomycorrhiza species group. Brighter-colored leaves (red > brown > yellow > yellow-green > green) tended to have lower N and P concentrations and higher C:N and C:P than darker-colored leaves. The random forest model showed that autumn coloration and leaf-fall phenology contributed 80% to the total explanation of nutrient variability among species. The results increase our understanding of the variability in senesced-leaf nutrients as a strategy of woody plant nutrition in temperate forests.

Species coculture can increase agro-biodiversity and therefore constitutes an ecological intensification measure for agriculture. Rice-aquatic animal coculture, one type of species coculture, has been practiced and researched widely. Here, we review recent studies and present results of a quantitative analysis of literature on rice-aquatic animal coculture systems. We address three questions: (i) can rice yield and soil fertility be maintained or increased with less chemical input through rice-aquatic animal coculture? (ii) how do aquatic animals benefit the paddy ecosystem? (iii) how can coculture be implemented for ecological intensification? Meta-analysis based on published papers showed that rice-aquatic animal cocultures increased rice yield, soil organic carbon and total nitrogen and decreased insect pests and weeds compared with rice monocultures. Studies also showed that rice-aquatic animal cocultures reduced pesticide and fertilizer application compared with rice monocultures. Rice plants provide a beneficial environment for aquatic animals, leading to high animal activities in the field. Aquatic animals, in turn, help remove rice pests and act as ecological engineers that affect soil conditions, which favor the growth of rice plants. Aquatic animals promote nutrient cycling and the complementary use of nutrients between rice and aquatic animals, which enhances nutrient-use efficiency in the coculture. To generate beneficial outcomes, how to develop compatible partnerships between rice and aquatic animals, and compatible culturing strategies for coculture systems are the key points. Investigating which traits of aquatic animals and rice varieties could best match to create productive and sustainable coculture systems could be one of the future focuses.

The evolution and expression of floral traits are responsive to selection pressure from biotic and abiotic factors. Although floral traits significantly vary among environments, the flower remains unchanged. We aimed to understand the adaptation of Epimedium chlorandrum of floral traits to a frequently nocturnally rainy and wet environments and the roles of floral traits in pollination and reproduction. We observed flowering phenology, measured floral characteristics including the number of pollen grains and ovules per flower, measured pollen viability and stigma receptivity, tested the volume and sugar concentration of nectar and conducted flower-visit observations in this species. Different pollination treatments were performed to characterize the breeding system. The inner sepals and highly curved longer spurs of E. chlorandrum jointly formed an umbrella that shielded the anthers and stigma from rain wash and prevented nectar dilution. Epimedium chlorandrum was visited by six species, while Bombus trifasciatus was the only effective pollinator and fed on the nectar. One flower secreted approximately 17.06 µL of nectar with a 29.19 g/100 mL sugar concentration, and the pollination efficiency of B. trifasciatus was positively associated with the nectar sugar concentration. The self- and open-pollination treatments resulted in fewer fertile seeds than the cross-pollination treatment. In contrast, the autonomous self- pollination treatment failed to yield fertile seeds. In summary, pollen limitation caused by harsh weather and pollinator shortage occurred during the pollination process of E. chlorandrum, which was partially alleviated by self-compatibility.

Plant invasion is one of the most serious threats to ecosystems worldwide. When invasive plants with the ability of clonal growth invading or colonizing in new habitat, their interconnected ramets may suffer from heterogeneous light. Effects of clonal integration on allelopathy of invasive plants are poorly understood under heterogeneous light conditions. To investigate the effects of clonal integration on allelopathy of invasive plant Wedelia trilobata under heterogeneous light conditions, a pot experiment was conducted by using its clonal fragments with two successive ramets. The older ramets were exposed to full light, whereas the younger ones were subjected to 20% full light. The younger ramets of each clonal fragment were adjacently grown with a target plant (one tomato seedling) in a pot. Stolon between two successive ramets was either severed or retained intact. In addition, two tomato seedlings (one as target plant) were adjacently grown in a pot as contrast. Compared with severing stolon, biomass accumulation, foliar chlorophyll and nitrogen contents, chlorophyll fluorescence parameters and net photosynthetic rates of the target plants as well as their root length and activity, were significantly decreased when stolon between interconnected ramets of W. trilobata retained intact. Under heterogeneous light conditions, transportation or sharing of carbohydrate between two successive ramets enhanced allelopathy of the young ramets subjected to 20% full light treatment. It is suggested that clonal integration may be important for invasion or colonization of invasive plants with ability of clonal growth under heterogeneous light conditions.