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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

In the Eurasian forest-steppe, with increasing aridity, the balance between naturally co-existing forest and grassland patches is expected to shift towards grassland dominance in the long run, although feedback mechanisms and changes in land-use may alter this process. In this study, we compared old and recent aerial photographs of Hungarian forest-steppes to find out whether and how the forest proportion and the number of forest patches change at the decadal time scale. The percentage area covered by forest significantly increased in all study sites. The observed forest encroachment may be a legacy from earlier land-use: due to ceased or reduced grazing pressure, forests are invading grasslands until the potential forest cover allowed by climate and soil is reached. The number of forest patches significantly increased at one site (Fülöpháza), while it decreased at two sites (Bugac and Orgovány) and showed no significant change at the fourth site (Tázlár). This indicates that forest encroachment can happen at least in two different ways: through the emergence of new forest patches in the grassland, and through the extension and coalescence of already existing forest patches. Though the present work revealed increasing tree cover at a decadal time scale, the dynamic process should be monitored in the future to see how the vegetation reacts to further aridification. This could help devise a conservation strategy, as the woody/non-woody balance has a profound influence on basic ecosystem properties.

Climate refugia can serve as a remnant habitat or stepping stones for species dispersal under climate warming. The largest freshwater lake by surface area, Lake Superior, USA and Canada, serves as a model system for understanding cooling-mediated local refugia, as its cool water temperatures and wave action have maintained shoreline habitats suitable for southern disjunct populations of arctic–alpine plants since deglaciation. Here, we seek to explain spatial patterns and environmental drivers of arctic–alpine plant refugia along Lake Superior’s shores, and assess future risk to refugia under moderate (+3.5 °C) and warmest (+5.7 °C) climate warming scenarios. First, we examined how the interactive effects of summer surface water temperatures and wind affected onshore temperatures, resulting in areas of cooler refugia. Second, we developed an ecological niche model for the presence of disjunct arctic–alpine refugia (pooling 1253 occurrences from 58 species) along the lake’s shoreline. Third, we fit species distribution models for 20 of the most common arctic–alpine disjunct species and predicted presence to identify refugia hotspots. Finally, we used the two climate warming scenarios to predict changes in the presence of refugia and disjunct hotspots. Bedrock type, elevation above water, inland distance, July land surface temperature from MODIS/Terra satellite and near-shore depth of water were the best predictors of disjunct occurrences. Overall, we predicted 2236 km of the shoreline (51%) as disjunct refugia habitat for at least one species under current conditions, but this was reduced to 20% and 7% with moderate (894 km) and warmest (313 km) climate change projections.

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.

A meandering riverbank plays a vital role in maintaining natural river ecosystems, providing habitats for riparian vegetation. However, dams have significantly altered riverbank shapes. To restore the riparian ecosystems, it is imperative to understand how different riverbank curvatures influence them. This study aims to uncover the ecological impacts of riverbank curvature on the structure and assembly process of plant communities in the riparian zone of the Yangtze River, regulated by the Three Gorges Dam (TGD) in China. We categorized the riparian zones into four types: cove, lobe, wavy and linear shapes. We documented the composition and diversity of riparian plant communities. Our findings revealed that wavy and cove riverbanks exhibited greater species diversity (with Shannon–Wiener diversity index values 1.5× higher) compared to communities along linear riverbanks. Furthermore, the analysis of functional traits indicated that wavy riverbanks promoted the differentiation of plant functional traits, thus enhancing ecosystem functions, with functional dispersion index (FDis) values 1.3 times higher than those of linear riverbanks. Significant variations in the assembly of riparian communities were also observed among different riverbanks, with standardized effect size (SES) values indicating a higher degree of niche differentiation in cove riverbanks (SES = 0.4) compared to linear riverbanks (SES = –0.6). These results highlight the ecological importance of diverse riverbank curvatures in influencing the diversity, structure and assembly of riparian communities along the waterway. In summary, this study underscores the necessity of maintaining or restoring various natural morphological curvatures when rehabilitating riparian communities along rivers impacted by human activities.

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.

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.

Grazing exerts a profound influence on both the plant diversity and productivity of grasslands, while simultaneously exerting a significant impact on regulating grassland soil carbon sequestration. Moreover, besides altering the taxonomic diversity of plant communities, grazing can also affect their diversity of functional traits. However, we still poorly understand how grazing modifies the relationship between plant functional diversity (FD) and soil carbon sequestration in grassland ecosystems. Here, we conducted a grazing manipulation experiment to investigate the effects of different grazing regimes (no grazing, sheep grazing (SG) and cattle grazing (CG)) on the relationships between plant FD and soil carbon sequestration in meadow and desert steppe. Our findings showed that different livestock species changed the relationships between plant FD and soil organic carbon (SOC) in the meadow steppe. SG decoupled the originally positive relationship between FD and SOC, whereas CG changed the relationship from positive to negative. In the desert steppe, both SG and CG strengthened the positive relationship between FD and SOC. Our study illuminates the considerable impact of livestock species on the intricate mechanisms of soil carbon sequestration, primarily mediated through the modulation of various measures of functional trait diversity. In ungrazed meadows and grazed deserts, maintaining high plant FD is conducive to soil carbon sequestration, whereas in grazed meadows and ungrazed deserts, this relationship may disappear or even reverse. By measuring the traits and controlling the grazing activities, we can accurately predict the carbon sequestration potential in grassland ecosystems.

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 tree height-diameter at breast height (H-DBH) and crown radius-DBH (CR-DBH) relationships are key for forest carbon/biomass estimation, parameterization in vegetation models and vegetation-atmosphere interactions. Although the H-DBH relationship has been widely investigated on site or regional scales, and a few of studies have involved CR-DBH relationships based on plot-level data, few studies have quantitatively verified the universality of these two relationships on a global scale. This study evaluated the ability of 29 functions to fit the H-DBH and CR-DBH relationships for six different plant functional types (PFTs) on a global scale, based on a global plant trait database. Results showed that most functions were able to capture the H-DBH relationship for tropical PFTs and boreal needleleaf trees relatively accurately, but slightly less for temperate PFTs and boreal broadleaf trees (BB). For boreal PFTs, the S-shaped Logistic function fitted the H-DBH relationship best, while for temperate PFTs the Chapman-Richards function performed well. For tropical needleleaf trees, the fractional function of DBH satisfactorily captured the H-DBH relationship, while for tropical broadleaf trees, the Weibull function and a composite function of fractions were the best choices. For CR-DBH, the fitting capabilities of all the functions were comparable for all PFTs except BB. The Logistic function performed best for two boreal PFTs and temperate broadleaf trees, but for temperate needleleaf trees and two tropical PFTs, some exponential functions demonstrated higher skill. This work provides valuable information for parameterization improvements in vegetation models and forest field investigations.

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.

In the early 20th century, numerous western botanists, often referred to as “plant hunters”, embarked on ambitious expeditions to China, playing a crucial role in the study of botany and botanical diversity. Despite their contributions, comprehensive assessments of their explorations are lacking. To bridge this gap, this article focuses on the work of Joseph Charles Francis Rock, a notable figure in that era. Our work revisits Rock’s botanical expeditions within the broader context of botanical diversity conservation. It outlines his historical experiences in collecting plants in China and enumerates the species composition and phenotypic traits of the plants he collected. Additionally, it also analyzes the spatial distribution of the species, the completeness of his collection, and the α-diversity and β-diversity of the plants he collected. Our findings reveal that Rock led four major botanical expeditions in China between 1922 and 1933, amassing a total of 28,184 sheets and 16,608 numbers across 204 families, 1,081 genera, and 4,231 species. His focus was predominantly on ornamental species, which exhibit a variety of flower colors and inflorescences. His collection work spanned 5 provinces, 35 cities, and 72 counties, with a notable concentration in the Hengduan Mountains, a current biodiversity hotspot. This study not only reconstructs Rock’s botanical legacy but also offers valuable historical data and fresh analytical insights for understanding contemporary plant diversity. It contributes to the ongoing discourse on the importance of preserving plant diversity as a cornerstone of environmental sustainability.

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.

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.

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.

In Mongolia, overgrazing and the resulting degradation of rangelands are recognized as serious issues. To address rangeland degradation, we sought to develop a broad-scale vegetation classification of Mongolian rangeland communities focusing on regional characteristics. Moreover, we sought to clarify the spatial distributions of communities and the environmental drivers of the distributions. Between 2012 and 2016, we surveyed vegetation in 278 plots (each 10 m × 10 m) in different regions of Mongolia (43-50° N, 87-119° E) in plots where grazing pressure is low relative to adjacent areas. The data were grouped into vegetation units using a modified two-way indicator species analysis (TWINSPAN). We then explored the regional characteristics of species compositions and community distributions, as well as relationships between distributions and climatic variables. The modified TWINSPAN classified the vegetation data into three cluster groups, each of which corresponds to a particular type of zonal vegetation (i.e. forest steppe, steppe and desert steppe). The aridity index was identified as an important driver of the distributions of all cluster groups, whereas longitude and elevation were important determinants of the distribution of clusters within cluster groups. Western regions, which are characterized by higher elevation and continentality compared with eastern regions, have lower mean temperature and precipitation during the wettest quarter, leading to differences in species composition within cluster groups. Regional differences in species composition reflect differences in phytogeographic origin. Thus, the framework of species composition and distributional patterns in Mongolian rangeland communities was demonstrated in relation to climatic and geographical factors.

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.

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.

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.

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).

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.

The accuracy of the simulation of carbon and water processes largely relies on the selection of atmospheric forcing datasets when driving land surface models (LSM). Particularly in high-altitude regions, choosing appropriate atmospheric forcing datasets can effectively reduce uncertainties in the LSM simulations. Therefore, this study conducted four offline LSM simulations over the Tibetan Plateau (TP) using the Community Land Model version 4.5 (CLM4.5) driven by four state-of-the-art atmospheric forcing datasets. The performances of CRUNCEP (CLM4.5 model default) and three other reanalysis-based atmospheric forcing datasets (i.e. ITPCAS, GSWP3 and WFDEI) in simulating the net primary productivity (NPP) and actual evapotranspiration (ET) were evaluated based on in situ and gridded reference datasets. Compared with in situ observations, simulated results exhibited determination coefficients (R²) ranging from 0.58 to 0.84 and 0.59 to 0.87 for observed NPP and ET, respectively, among which GSWP3 and ITPCAS showed superior performance. At the plateau level, CRUNCEP-based simulations displayed the largest bias compared with the reference NPP and ET. GSWP3-based simulations demonstrated the best performance when comprehensively considering both the magnitudes and change trends of TP-averaged NPP and ET. The simulated ET increase over the TP during 1982–2010 based on ITPCAS was significantly greater than in the other three simulations and reference ET, suggesting that ITPCAS may not be appropriate for studying long-term ET changes over the TP. These results suggest that GSWP3 is recommended for driving CLM4.5 in conducting long-term carbon and water processes simulations over the TP. This study contributes to enhancing the accuracy of LSM in water–carbon simulations over alpine regions.

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 ecology of plant species relies on the synchronous functioning of leaves and roots, but few studies have simultaneously examined the community trait dispersion (CTD) patterns of both organs. We measured 16 analogous leaf and root traits on 44 co-occurring woody species in a subtropical forest in southern China, aiming to examine whether leaf and root traits were coordinated, organized into parallel trait axes, exhibited similar CTD, and displayed consistent responses in CTD and community-weighted means of (CWM) traits over environmental gradients. While the first axes of leaf and root trait variation similarly exhibited a fast-slow continuum, leaf traits covered a secondary “carbon economics” axis, contrasting to root traits depicting a collaboration axis reflecting species’ mycorrhizal dependency. Analogous leaf and root chemical traits were generally coordinated but less so for morphological traits. At the community level, changes in the CWM of the first axes were generally consistent among organs with more conservative traits found as increasing elevation but not for the second axis. While root traits became thinner and more conservative as soil phosphorus concentration decreased, leaf traits rarely varied. When different trait axes were combined, leaf traits were overdispersed but tended to converge with increased elevation and soil potassium and phosphorus levels, whereas root traits were clustered but tended to diverge along the same gradients. Our study highlights fine filtering of different suites of traits above- and belowground, which in turn might reduce overall niche overlap among species and promote coexistence with diverse functional designs.

Asymmetric seasonal warming, characterized by more pronounced temperature increases in winter than in summer, has become a critical feature of global warming, especially in cold and high-altitude regions. Previous studies have primarily focused on year-round warming, while comparatively less attention was paid to winter warming. However, a significant knowledge gap exists regarding the impacts of winter warming on ecosystem functions. To address this, we conducted an 8-year manipulated warming experiment in an alpine grassland on the Tibetan Plateau, employing three treatments: no warming, year-round warming and winter warming. We found that neither year-round warming nor winter warming significantly alters species richness at the community level. Notably, community biomass stability was maintained via species asynchrony. However, warming exerted significant effects on the plant abundance groups (dominant, common and rare species). Specifically, winter warming enhanced the stability of dominant species by increasing species asynchrony of dominant species, as the compensatory dynamics occurred between the grass and forbs. In contrast, year-round warming reduced the stability of common species, correlated with an increase in species richness and a decline in asynchrony among common species. Thus, our study underscores the capacity of alpine grassland to maintain community biomass stability via asynchrony dynamics of species under different warming conditions, although the stability of different abundance groups would be changed. Importantly, our results provide valuable insights for understanding the alpine grassland ecosystem on the Tibetan Plateau.

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.

Evergreen and deciduous species coexist in the subtropical forests in southeastern China. It has been suggested that phosphorus (P) is the main limiting nutrient in subtropical forests, and that evergreen and deciduous species adopt different carbon capture strategies to deal with this limitation. However, these hypotheses have not been examined empirically to a sufficient degree. In order to fill this knowledge gap, we measured leaf photosynthetic and respiration rates, and nutrient traits related to P-, nitrogen (N)- and carbon (C)-use efficiencies and resorption using 75 woody species (44 evergreen and 31 deciduous species) sampled in a subtropical forest. The photosynthetic N-use efficiency (PNUE), respiration rate per unit N and P (R_d,N and R_d,P, respectively) of the deciduous species were all significantly higher than those of evergreen species, but not in the case of photosynthetic P-use efficiency. These results indicate that, for any given leaf P, evergreen species manifest higher carbon-use efficiency (CUE) than deciduous species, a speculation that is empirically confirmed. In addition, no significant differences were observed between deciduous and evergreen species for nitrogen resorption efficiency, phosphorus resorption efficiency or N:P ratios. These results indicate that evergreen species coexist with deciduous species and maintain dominance in P-limited subtropical forests by maintaining CUE. Our results also indicate that it is important to compare the PNUE of deciduous species with evergreen species in other biomes. These observations provide insights into modeling community dynamics in subtropical forests, particularly in light of future climate change.

Warming and grazing, and litter quality jointly determine litter decomposition and nutrient releases in grazing ecosystems. However, their effects have previously been studied in isolation. We conducted a two factorial experiment with asymmetric warming using infrared heaters and moderate grazing in an alpine meadow. Litter samples were collected from all plots in each treatment, among which some subsamples were placed in their original plots and other samples were translocated to other treatment plots to test the relative effects of each treatment on litter decomposition and nutrient releases. We found that warming rather than grazing alone significantly increased total losses of litter mass, total organic carbon, total nitrogen (TN) and total phosphorus (TP) per unit area due to increases in both mass loss rates and litter biomass. However, grazing with warming did not affect their total mass losses because increased mass loss was offset by decreased litter biomass compared with the control. Seasonal mean soil temperature better predicted litter decomposition than litter lignin content or carbon to nitrogen ratio. There were interactions between warming and grazing, but there were no interactions between them and litter quality on litter decomposition. The temperature sensitivity of TN loss was higher than that of TP loss per unit area. Our results suggest that increased temperature has a greater effect on litter decomposition and nutrient release than change in litter quality, and that more N release from litter could result in greater P deficiency in the alpine meadow.

Nutrient resorption is a crucial mechanism for plant nutrient conservation, but most previous studies did not consider the leaf-mass loss during senescence due to lack of measured data. This would lead to an underestimation of nutrient resorption efficiency (NuRE), or calculating NuRE of various species based on the average mass loss at plant-functional-group level in the literature, thus affecting its accuracy. Here we measured the leaf-mass loss to correct NuRE with the species-specific mass loss correction factor (MLCF), so as to foster a more accurate calculation of the nutrient fluxes within and between plants and the soil. Green leaves and senesced leaves were collected from 35 dominant woody plants in northern China. Mass of green and senesced leaves were measured to calculate the MLCF at species level. The MLCF was reported for each of the 35 dominant woody plants in northern China. These species averagely lost 17% of the green-leaf mass during leaf senescence, but varied greatly from 1.3% to 36.8% mass loss across the 35 species, or 11.7% to 19.6% loss across the functional types. Accordingly, the MLCF varied from 0.632 to 0.987 across the 35 species with an average value 0.832. The NuRE corrected with MLCF was remarkably increased on the whole (e.g. both the average nitrogen and phosphorus NuRE became about 9% higher, or more accurate), compared with the uncorrected ones, especially in the case of low resorption efficiencies. Our field data provide reliable references for the MLCF of plants in related regions at both species and functional-type levels, and are expected to promote more accurate calculations of NuRE.