Functional Diversity Of Plant Communities Research Articles

Effects of grazing on functional diversity along secondary succession in a tropical dry forest (Caatinga, Brazil)

AbstractAimLivestock production is among the main anthropogenic disturbances in seasonally dry tropical forests. However, its effects on plant functional composition in dry forests is poorly understood. Our goal was to analyze the variation in both functional composition and functional diversity of plant communities under goat grazing and at different ages of fallow in a tropical dry forest.LocationBrazilian dry forest (Caatinga) in Rio Grande do Norte State, northeastern Brazil.MethodsWe measured the height, leaf area, and specific leaf area of all shrub‐tree and herbaceous species along a gradient of stocking rate, years of grazing, and age of fallow. Additionally, we quantified the foliar contents of nitrogen, phosphorus, and tannins in the tree shrub layer. We tested the effects of grazing and deforestation using linear mixed models.ResultsOur findings suggest that the functional diversity of plant communities in the Caatinga is not altered when goat grazing and secondary succession are examined independently. However, the interaction of both factors has affected the functional diversity, particularly in the herbaceous layer. Although grazing influenced specific traits in the shrub‐tree layer, the overall functional diversity remained unaltered by grazing, succession, or their interaction.ConclusionsGrazing does not interfere with the natural succession process nor diminish the functional diversity of plant communities in the Caatinga. Therefore, with appropriate management, grazing can coexist with the conservation goals of the Caatinga.

Functional diversity along disturbance and environmental gradients in Ethiopian moist Afromontane forest

Considering multiple measures to fully capture functional diversity is important. However, the effects of disturbance gradients on diversity have been controversial, as species diversity alone may not fully capture these effects. This study aimed to evaluate trait-based diversity across disturbance gradients in the moist Afromontane forest of Ethiopia, Yayu Coffee Forest Biosphere Reserve (YCFBR). Vegetation data and relevant traits related to plant-life strategies, competition, and responses to disturbances were collected. A multiple regression model was used to test the response of functional diversity to disturbances and environmental gradients. The results revealed functional diversity in plant communities, including dendrogram-based functional diversity for plot-based (FDp), functional richness (FRic), functional evenness (FEve), functional divergence (FDiv), functional dispersions (FDis), and community-weighted mean of maximum tree height (CWM.Hmax), showed decreasing patterns with increasing disturbance intensity in the YCFBR. Additionally, the findings highlighted that FDis and Hmax are the most vulnerable functional traits to anthropogenic factors and are less tolerant in disturbed ecosystem environments. Therefore, reducing disturbances is crucial to maintaining higher levels of these functional diversities. For example, the results showed that the CWM.Hmax declined from 27.25 m to 15 m, indicating a shift towards shorter plant species. In contrast, the community-weighted mean of woody density (CWM.WD), the community-weighted mean of specific leaf area (CWM.SLA), and the community-weighted mean of seed mass (CWM.SM) increased significantly with an increase in disturbance intensity. For instance, CWM.SM and CWM.SLA changed from 5 to 14.25 (g) and 90 to 130 (cm2/g), respectively. These indices may serve as indicators of ecosystem resilience at disturbed forest ecosystem sites. Furthermore, the regression results indicated that FDp, FRic, FEve, FDiv, FDis, CWM.WD, and CWM.Hmax showed increasing patterns with increasing species richness, which suggests that protecting and promoting species diversity can contribute to maintaining high levels of functional diversity. The mixed effects model revealed that anthropogenic disturbance and elevational gradients had significant effects on functional diversity in the YCFBR. Therefore, when managing and conserving biodiversity in heterogeneous environments, both anthropogenic factors and environmental variables need to be considered. Species with low SLA and SM are recommended for the restoration of disturbed ecosystems. Overall, this study demonstrates that trait-based functional diversity is useful for predicting the adaptation potentials of species in heterogeneous environments and disturbance gradients.

Drivers and mechanisms of spontaneous plant community succession in abandoned Pb[sbnd]Zn mining areas in Yunnan, China

The drivers and mechanisms underlying succession and the spontaneous formation of plant communities in mining wasteland remain largely unknown. This study investigated the use of nature-based restoration to facilitate the recovery of viable plant communities in mining wasteland. It was found that scientific analyses of spontaneously formed plant communities in abandoned mining areas can provide insights for nature-based restoration. A chronosequence (“space for time”) approach was used to establish sites representing three successional periods with six successional stages, and 90 quadrats were constructed to investigate changes in plant species and functional diversity during succession in abandoned PbZn mining areas. A total of 140 soil samples were collected to identify changes in soil properties, including plant nutrient and heavy metal concentrations. Then, this paper used structural equation models to analyze the mechanisms that drive succession. It was found that the functional diversity of plant communities fluctuated substantially during succession. Species had similar functional traits in early and mid-succession, but traits tended to diverge during late succession. Soil bulk density and soil organic matter gradually increased during succession. Total nitrogen (N), pH, and soil Zn concentrations first increased and then decreased during succession. Concentrations of Mn and Cd gradually decreased during succession. During early succession, soil organic matter was the key factor driving plant colonization and succession. During mid-succession, soil Zn functioned as an environmental filter factor limiting the rates of succession in mining wasteland communities. During late succession, soil bulk density and competition for nutrient resources contributed to more balanced differentiation among plant species. This thesis proposed that a nature-based strategy for the stabilization of abandoned mining lands could facilitate effective plant community restoration that promotes ecosystem services and functioning.

Site dependence of local variations in taxonomic and functional diversity of plant communities in semi-natural dry grasslands

Site dependence of local variations in taxonomic and functional diversity of plant communities in semi-natural dry grasslands

Water management infrastructure alters plant species composition, functional diversity and soil condition in a livestock‐impaired mosaic of wetlands

AbstractAimsWetlands are key ecosystems due to their economic, social and environmental contributions. Because of their highly productive habitats and their dependence on hydro‐meteorologic regimes, they are threatened worldwide by land use and climate change. In most wetlands, intensification of productive activities has been mostly accompanied by the implementation of a water management infrastructure, disrupting water and nutrient dynamics. Our aim was to analyze whether intensification of livestock raising erodes the structure and function of plant communities, as well as the quality and fertility of soils in wetlands.LocationNon‐insular portion of the Lower Delta of the Paraná River, Argentina.MethodsPlant communities were characterized on the basis of their floristic composition, structural and functional diversity. Soil samples were also collected to assess soil fertility, texture and quality. Generalized mixed linear models were used to contrast these attributes across livestock management practices characterized by differing water management infrastructure (polders and channelizations) and livestock type (bovine, bubaline).ResultsRemarkably fertile hydromorphic soils supported a structurally rich and functionally diverse species composition. Nevertheless, most dominant populations were terrestrial, perennial, invasive species, partially adapted to conditions of temporary flooding. Polderized livestock fields exhibited not only the lowest quality, least fertile, most compacted soils, but also lower species richness and diversity, as well as the lowest values in all non‐redundant components of functional diversity. Channelized livestock fields exhibited lower species richness and taxonomic diversity as well as reduced soil quality and fertility, yet an overall increase in most non‐redundant components of functional diversity.ConclusionsPromoting the loss of native flora, water management infrastructure impairs the sustainability of anthropic activities and thwarts biodiversity conservation efforts. Traditional and sustainable practices that embrace the periodicity of the flood pulse are required to preserve the taxonomic and functional diversity of plant communities, as well as the quality and fertility of soils.

Levels of Natural and Anthropogenic Disturbances and Assessment of Their Impact on Plant Community Functional Diversity

Levels of Natural and Anthropogenic Disturbances and Assessment of Their Impact on Plant Community Functional Diversity

Relationship between diversity and stability of a karst plant community

The relationships among species diversity, functional diversity, functional redundancy, and community stability are central to community and ecosystem ecology. In this paper, a “space substitution for time” approach is used to study the plant communities at different stages of the natural recovery process of degraded karst vegetation on the karst plateau of Guizhou. These restoration stages include the herbaceous stage, herbaceous and shrub transition stage, shrub stage, tree and shrub transition stage, and tree stage. We calculated the functional diversity and functional redundancy of the community based on functional characteristics and mediated the relationship between functional diversity, functional redundancy, and stability of the plant community through changes in functional diversity and functional redundancy. This study aims to reveal the mechanisms of changes in species diversity and community stability and thus further reveals the intrinsic reasons for maintaining the stability of karst plant communities. The most important results include the following: (1) Species diversity, functional redundancy, and stability gradually increased with restoration, and there were significant differences among the different stages; functional diversity increased at first and then decreased, and reached the highest level at the tree and shrub transition stage; (2) Plant height and specific leaf area were functional traits that influenced the diversity and stability of the plant community, with plant height being positively correlated with plant community diversity and stability, and specific leaf area being negatively correlated with plant community diversity and stability; (3) During the community's recovery, functional diversity and functional redundancy interacted to maintain stability. In the early and late stages of recovery, the effect of functional redundancy on stability was greater than that of functional diversity, but it was the opposite in the middle stages; (4) The tree and shrub transition stage is the likely point at which the functional diversity of plant communities in karst areas reaches saturation, and the growth rate of functional redundancy after functional diversity saturation is greater than that before saturation. Overall, community stability increased with species diversity; habitat heterogeneity increased functional diversity in the early stages of recovery; and habitat homogeneity increased functional redundancy.

Functional Diversity of Plant Communities in Relationship to Leaf and Soil Stoichiometry in Karst Areas of Southwest China

Assessment of relationships between functional diversity and ecological stoichiometry in plant communities can aid in determining the relative variability and ecological complementarity of functional attributes among species, which is a better approach to understanding ecosystem processes and functions than studying species taxonomic diversity. Here, we analyzed the relationships among community weighted means of functional traits, functional diversity, and leaf and soil chemical properties of plant communities during various stages of vegetation restoration in Mao Lan National Karst Forest Nature Reserve, located in humid subtropical Guizhou of China. Our results showed significant changes in four weighted functional traits of plant communities at different restoration stages, namely, plant height, leaf width to leaf length ratio, and leaf area. Additionally, with the progression of the recovery of plant communities, functional richness, functional separation, and quadratic entropy, the coefficient tended to increase. Functional divergence tended to gradually decrease. The association of functional diversity with soil chemical properties was stronger than that with leaf ecological stoichiometry. Regarding leaf and soil chemical properties, soil phosphorus content and leaf C:P were particularly important in influencing functional diversity. Our overall findings indicate that functional traits shift from “acquisitive” to “conservative” as the community is restored. Karst plant communities reduce interspecific resource competition as restoration proceeds, thereby increasing functional overlap effects.

Relationship between functional diversity and ecosystem multifunctionality of alpine meadow along an altitude gradient in Gannan, China

Relationship between plant community functional diversity and ecosystem multifunctionality (EMF) was a new area of ecological research in recent years. Previous studies had mostly focused on the relationship between plant community functional diversity and individual ecosystem function, and lack of understanding of the EMF. In this study, six functional indices of aboveground biomass, soil organic carbon, soil total nitrogen, soil total phosphorus, soil available nitrogen and soil available phosphorus of Gannan alpine meadow were selected to analyze the relationship between plant community functional diversity and EMF on the altitude gradient of Gannan alpine mea-dow by using Bartlett sphericity test and multi-threshold method. The results showed that there was significant altitudinal difference in plant community composition, with species richness and plant coverage at 3500 m were significantly higher than those at other altitudes. Single and multi-functional diversity decreased with the increases of altitude, with significant difference among altitudes. Redundancy analysis showed that single and multi-functional richness, functional evenness and Rao's quadratic entropy were significantly positively correlated with soil temperature, soil water content and soil bulk density, and significantly negatively correlated with soil pH and soil conductivity. In a large threshold range (6%-89%), functional diversity had a significant positive effect on EMF. Based on correlation analysis, optimal regression model and random forest model, it was found that multi-functional richness index had a significant positive relationship with EMF, and that multi-functional richness was also the main driving factor of EMF. Overall, functional richness had the most significant impact on the EMF of alpine meadow in the Qinghai-Tibet Plateau.

Deciphering the role of specialist and generalist plant-microbial interactions as drivers of plant-soil feedback.

Feedback between plants and soil microbial communities can be a powerful driver of vegetation dynamics. Plants elicit changes in the soil microbiome that either promote or suppress conspecifics at the same location, thereby regulating population density-dependence and species co-existence. Such effects are often attributed to the accumulation of host-specific antagonistic or beneficial microbiota in the rhizosphere. However, the identity and host-specificity of the microbial taxa involved are rarely empirically assessed. Here we review the evidence for host-specificity in plant-associated microbes and propose that specific plant-soil feedbacks can also be driven by generalists. We outline the potential mechanisms by which generalist microbial pathogens, mutualists and decomposers can generate differential effects on plant hosts and synthesize existing evidence to predict these effects as a function of plant investments into defence, microbial mutualists and dispersal. Importantly, the capacity of generalist microbiota to drive plant-soil feedbacks depends not only on the traits of individual plants but also on the phylogenetic and functional diversity of plant communities. Identifying factors that promote specialization or generalism in plant-microbial interactions and thereby modulate the impact of microbiota on plant performance will advance our understanding of the mechanisms underlying plant-soil feedback and the ways it contributes to plant co-existence.

Functional traits of plants and pollinators explain resource overlap between honeybees and wild pollinators

Managed and wild pollinators often cohabit in both managed and natural ecosystems. The western honeybee, Apis mellifera, is the most widespread managed pollinator species. Due to its density and behaviour, it can potentially influence the foraging activity of wild pollinators, but the strength and direction of this effect are often context-dependent. Here, we observed plant–pollinator interactions in 51 grasslands, and we measured functional traits of both plants and pollinators. Using a multi-model inference approach, we explored the effects of honeybee abundance, temperature, plant functional diversity, and trait similarity between wild pollinators and the honeybee on the resource overlap between wild pollinators and the honeybee. Resource overlap decreased with increasing honeybee abundance only in plant communities with high functional diversity, suggesting a potential diet shift of wild pollinators in areas with a high variability of flower morphologies. Moreover, resource overlap increased with increasing trait similarity between wild pollinators and the honeybee. In particular, central-place foragers of family Apidae with proboscis length similar to the honeybee exhibited the highest resource overlap. Our results underline the importance of promoting functional diversity of plant communities to support wild pollinators in areas with a high density of honeybee hives. Moreover, greater attention should be paid to areas where pollinators possess functional traits similar to the honeybee, as they are expected to be more prone to potential competition with this species.

Effects of Soil Properties, Temperature and Disturbance on Diversity and Functional Composition of Plant Communities Along a Steep Elevational Gradient on Tenerife

Elevational variation of vegetation has been of interest for centuries, and a prominent example for such pronounced vegetation changes can be found along the steep elevational gradient on Tenerife, Canary Islands, 200 km off the West-African cost. The 3,718-m ascent to the peak of the island volcano, Teide, offers a unique opportunity to investigate associated changes in vegetation. However, elevation is not a directly acting factor, but represents several natural environmental gradients. While the elevational variation of temperature is globally rather uniform and temperature effects on plant communities are well understood, much less is known about the region-specific elevational change of chemical soil properties and their impact on plant communities along elevational gradients. Because human interference takes place even at high-elevation areas, we considered human-induced disturbance as important third factor acting upon plant community assemblages. In our study, we compared the effects of soil properties, temperature and disturbance on species richness, functional identity and functional diversity of plant communities along the elevational gradient on Tenerife. We used pairs of study plots: directly adjacent to a road and in natural vegetation close by. In each plot, we did vegetation relevées, took soil samples, and installed temperature loggers. Additionally, we collected leaf samples to measure leaf functional traits of 80% of the recorded species. With increasing elevation, soil cation concentrations, cation exchange capacity (CEC) and pH decreased significantly, while the soil carbon to phosphorus ratio slightly peaked at mid-elevations. Temperature had the strongest effects, increasing species richness and favoring communities with fast resource acquisition. Species richness was higher at road verges, indicating the positive effect of reduced competition and artificially generated heterogeneity. However, we did not detect road effects on plant functional characteristics. Vice versa, we did not find soil effects on species richness, but increased concentrations of soil cations favored acquisitive communities. Surprisingly, we could not reveal any influence on community functional diversity. The importance of temperature aligns with findings from large-scale biogeographic studies. However, our results also emphasize that it is necessary to consider the effects of local abiotic drivers, like soil properties and disturbance, to understand variation in plant communities.

Functional diversity response to geographic and experimental precipitation gradients varies with plant community type

Abstract Precipitation is a primary determinant of plant community structure in drylands. However, the empirical evidence and predictions are lacking for how plant functional diversity in desert and steppe communities respond to altered precipitation regimes. We examined how precipitation changes along the natural and experimental gradients affect different components of functional diversity in desert‐shrub and steppe‐grass communities. We compared the associations of precipitation changes with community‐weighted means (CWMs) of six traits, functional divergence (FDvar) of each single‐trait and multi‐trait functional richness (FRic) and dispersion (FDis) for shrub and grass communities along the natural and experimental gradients. We also disentangle the roles of species turnover and intraspecific variations in affecting the responses of different functional diversity to precipitation changes. We found that in general, the similar responses of functional traits or diversity to both the natural and experimental precipitation gradients were dependent on plant community type. Across both two gradients, precipitation was positively associated with CWM of plant height and negatively associated with the CWM of SLA and leaf thickness in grass community, while positively associated with FDvar of four traits and FDis in shrub communities. Both species turnover and intraspecific variations contributed to the responses of grass community traits to precipitation changes across both two gradients, and to FDvar of traits and FDis in shrub community along the natural gradient. In contrast, species turnover variations contributed to FDvar of traits and FDis in shrub community in experiment. These results suggest that there is better concordance between the effects of naturally and experimentally increased precipitation on functional diversity of plant communities, but different mechanisms behind the relationship of functional diversity–precipitation between shrub and grass communities. Grass communities can adapt to precipitation changes by average trait differences, while shrub communities persist through FDvar of single‐trait and multi‐trait dispersion, thus highlighting the important differences in adaptive strategies between shrub and grass communities. Our findings demonstrate that short‐term responses of plant communities to manipulative precipitation changes can reflect long‐term shifts at spatial scales depending on the specific functional trait and diversity. A free Plain Language Summary can be found within the Supporting Information of this article.

Mining and quarrying activities tend to favor stress-tolerant plants

Anthropogenic activities such as mining and agricultural practices may alter plant community structure and functioning. Grime’s Competitors–Stress–Ruderal (CSR) strategy can be used to detect plant community transformations caused by environmental changes. We examined the effects of mining and quarrying activities on CSR strategies, species diversity, functional composition (community-weighted mean – CWM), and functional diversity (Rao’s and Mason’s indexes) of plant species from nearby an active Cu-Pb-Zn mine site and an agricultural site away from the mine.We determined the ecological strategies of 34 species using 13 functional traits. We found that ruderal strategy (e.g., high R-scores) was dominant in the agricultural site, whereas stress-tolerant species (e.g., high S-scores) were abundant in the mine site according to “StrateFy” that is a globally calibrated CSR analysis tool. Community-weighted mean (CWM) trait values were greater in the agricultural site where has relatively higher soil fertility than in the stressful mine site (e.g., low pH and heavy metal stress). Although species diversity was higher in the mine site, functional diversity in the agricultural site was slightly higher than that in the mine site as indicated by greater Rao’s and Mason’s index values.Our findings suggest that the effect of anthropogenic activities might be detected using CSR strategies both at species and community levels. Mining activities may favor stress-tolerant species, whereas agricultural practices (e.g., fertilization and mowing disturbance) may favor ruderal species in accordance with the CSR theory predictions. “StrateFy” CSR analysis tool can help us to quickly track shifts in ecological strategies of plants in response to changes in the environment and land-use. Therefore, CSR strategies can be used as bioindicators of anthropogenic activities. Moreover, under increasing abiotic stress, functional diversity of plant communities may decrease which can have crucial effects on community-level responses and eventually ecosystem functioning and services.

A functional trait‐based approach to assess the impact of an alien palm invasion on plant and soil communities on a South Pacific island

AbstractIn island ecosystems, biological invasions are one of the major threats to native biodiversity and to ecosystem functioning. Invasive ornamental plants such as the alien palm tree Pinanga coronata in the Fiji islands can form mono‐dominant stands in rainforests and displace native species. Using a functional trait‐based approach, we investigated the impact of P. coronata on both above and belowground communities (i.e. plants and Collembola). Within a rainforest reserve on Fiji´s principal island, we sampled a total of 10 invaded and non‐invaded plots and recorded five functional traits for plants and six for Collembola. We found that invasion by P. coronata led to a strong and significant decrease of native plants and Collembola taxonomic diversity. Ingress of P. coronata also induced a decrease in the functional diversity of plant communities and to a lesser extent of Collembola communities. P. coronata invasion led to a decrease of leaf carbon–nitrogen ratio (LCN), Leaf nitrogen content (LN), specific leaf area (SLA) and leaf dry matter content (LDMC) of plant communities, suggesting a change in litter properties compared to non‐invaded communities. Plots with P. coronata were associated with large Collembola living at the soil surface with more trichobothria and pseudocelli, which are used as defence mechanisms. Using trait‐matching, we also found that the strength of plant‐soil relationships was higher (i.e. more stable) in non‐invaded plots than in P. coronata‐invaded plots. Lastly this study suggests that the main mechanism through which P. coronata alters soil communities is a change in plant properties rather than a change in the abiotic environment. Our trait‐based approach underlines the negative impact of this alien palm invasion on native rainforest plant and soil fauna in Fiji, and the urgent need for on‐the‐ground action to conserve terrestrial island biodiversity in Fiji´s rainforests.

Functional diversity of plant communities at edge and interior of a submontane Atlantic Forest: greater functional than compositional stability

Abstract We compared the functional diversity of community at edge and interior areas of an Atlantic forest fragment to test the hypothesis that higher functional diversity exists along edges - in consonance with their higher abundance and floristic diversity as compared to the interior of the forest. By considering a set of vegetative, reproductive and phenological traits and ecosystem service aspects of edge and interior environments, we defined plant functional groups using Cluster Analysis, followed by a silhouette width analysis, together with functional diversity indices of richness, divergence, evenness and dispersion. The main functional groups formed were similar between the edges and interior. Functional richness was the only index that demonstrated differences between edge and the interior. Alterations were perceived in relation to species richness and the Shannon index. Edge effects were not significant in the formation of functional groups. In contrast to our original hypothesis, similar groups were formed both along the edge in the interior - indicating that species played similar ecological roles in both environments, with similar responses to different environmental factors - so that forest edges were colonized by a series of different species that maintained diversity patterns similar to those found in the forest interior.

Pattern of functional diversity along the elevation gradient in the dry evergreen Afromontane forest of Hararghe Highland, Southeast Ethiopia

Understanding plant species distribution patterns along environmental gradients is fundamental to managing ecosystems, particularly when habitats are fragmented due to intensive human land use pressure. The variation pattern of functional diversity of plant communities along the elevation gradient in the Dindin dry evergreen Afromontane forest was tested. Fifty four plots of 20 x 20 m (400 m2) were established at 200 m intervals starting 2,300–2,900 m a. s. l. and woody species composition, and environmental variables were recorded. Nine functional diversity indices based on functional distances were employed to esimate functional diversity. The mixed effect model was used to determine the effect of elevation, aspect and slope on functional diversity indices. The results showed that functional diversity in communities varied greatly; functional diversity revealed a decrease with increasing elevation and a‘‘humped’’ pattern, with peak diversity appearing at middle elevation. Functional diversity was significantly correlated with elevation, slope, and aspect. Functional diversity was significantly correlated with species richness and evenness. Environmental filtering was important to the functional diversity pattern; the nine indices were all successful in the analysis of functional diversity in the plant community with different effectiveness, and modified functional attribute diversity, plot-based functional diversity, community based functional diversity, functional richness, and community weight mean of woody density performed better than the other four indices in this study.

Tropical carbon sink accelerated by symbiotic dinitrogen fixation

A major uncertainty in the land carbon cycle is whether symbiotic nitrogen fixation acts to enhance the tropical forest carbon sink. Nitrogen-fixing trees can supply vital quantities of the growth-limiting nutrient nitrogen, but the extent to which the resulting carbon–nitrogen feedback safeguards ecosystem carbon sequestration remains unclear. We combine (i) field observations from 112 plots spanning 300 years of succession in Panamanian tropical forests, and (ii) a new model that resolves nitrogen and light competition at the scale of individual trees. Fixation doubled carbon accumulation in early succession and enhanced total carbon in mature forests by ~10% (~12MgC ha−1) through two mechanisms: (i) a direct fixation effect on tree growth, and (ii) an indirect effect on the successional sequence of non-fixing trees. We estimate that including nitrogen-fixing trees in Neotropical reforestation projects could safeguard the sequestration of 6.7 Gt CO2 over the next 20 years. Our results highlight the connection between functional diversity of plant communities and the critical ecosystem service of carbon sequestration for mitigating climate change.

Functional diversity is a passenger but not driver of drought‐related plant diversity losses in annual grasslands

Abstract Effects of climate change on plant community functional diversity are of interest since experiments have found functional diversity to predict ecosystem function. Functional diversity has been hypothesized to confer resilience to plant communities (as a “driver” of community change), but in unmanipulated natural communities, it might alternatively (or additionally) act as a “passenger” by responding to changes in plant diversity caused by extrinsic factors such as climate. We examined trends in plant functional diversity in annual grasslands in Northern California over a 19‐year period, during which a trend towards drier winters had previously been associated with the losses of drought‐intolerant species. We tested whether functional diversity decreased over the period of the study (acting as a passenger), and also whether initial site functional diversity influenced the degree of community change over the study period (acting as a driver). Initial community functional diversity was not related to species richness loss or community variability. We found that functional diversity declined as plant species richness and community mean specific leaf area declined over the course of the study, and all of these trends were associated with declining precipitation, indicating that functional diversity acted as a passenger of community change. Synthesis. This study is among the first to demonstrate that recent climatic trends may drive loss of functional diversity. Our findings highlight that functional diversity does not necessarily confer community resilience when its variation is shaped by the environment rather than by experimental treatments.

Erigeron canadensis affects the taxonomic and functional diversity of plant communities in two climate zones in the North of China

AbstractPlant communities across multiple climate zones are at risk of invasive species. Understanding the effects of invasive alien species on both the taxonomic and functional diversities of plant communities in different climate zones enables insight into the mechanisms underlying successful invasions. This study investigated the effects of Erigeron canadensis at different degrees of invasion on both the plant taxonomic and functional diversities in the Chinese zones of Jinan (warm temperate climate) and Zhenjiang (north subtropical climate). A high degree of E. canadensis invasion resulted in a stronger decrease of plant diversity compared to a light degree of E. canadensis invasion. This may be because E. canadensis invasion can lead to a decrease in the number of native species via competition and subsequent local extinction. A high degree of E. canadensis invasion increased the Rao's quadratic entropy of plant height and ground cover. This may be because both the plant height and ground cover of E. canadensis and natives increased with increasing degree of E. canadensis invasion. The number of plant species in plant communities was lower in Jinan than in Zhenjiang. This is presumably because E. canadensis grows better in Jinan than in Zhenjiang and therefore, rare species are more likely to go extinct there. A small number of functional diversity indices of Jinan plant communities were higher than those of Zhenjiang. This may be due to the higher value of functional traits of E. canadensis in Jinan.