Plant Beta Diversity Research Articles

Contrasting responses of plant, soil fungal and above‐ground arthropod communities to plant invasion across latitudes

Abstract The proliferation of alien species that can suppress resident species via biotic interactions represents a growing concern worldwide. Yet, how above‐ and below‐ground communities simultaneously respond to plant invasion, particularly across large spatial scales, remains poorly explored. We hypothesized plant invasion has a greater impact on recipient above‐ and below‐ground communities at lower than higher latitudes given that biotic interactions play a more significant role in shaping communities in more favourable, lower latitude environments. To test this hypothesis, we conducted a comprehensive field survey of 124 sites spanning a 1700‐km latitudinal gradient in China, to explore the effects of invasion of Alternanthera philoxeroides, a globally widespread invasive plant, on plant, soil fungal and above‐ground arthropod communities. Invasion of A. philoxeroides had divergent effects on beta diversity (i.e. variation in taxa composition among sites) of plants, above‐ground arthropods and soil saprotrophic fungi, with negative, neutral and positive responses, respectively. Notably, the compositional dissimilarity of plant and arthropod communities between adjacent invaded and non‐invaded sites remained constant across latitudes. In contrast, the compositional dissimilarity of the entire and pathogenic fungal communities between adjacent invaded and non‐invaded sites increased with latitude. This resulted in a decreasing difference in invasion effects on the composition of plant and fungal communities with increasing latitude. Synthesis. Our study provides novel insights into the complexities of invasion effects by revealing contrasting responses of above‐ and below‐ground communities to plant invasion across latitudes. The contrasting responses could weaken or reshape above‐ and below‐ground interactions, and, in turn, affect future species invasions and the functioning of terrestrial ecosystems.

Climate-driven environmental filtering determines hump-shaped elevational pattern of seed plant beta diversity in the central Himalayas

Understanding how and why assemblage dissimilarity changes along spatial gradient is a great challenge in ecology, because answers to these questions depend on the analytical types, dimensions, and components of beta diversity we concerned. To obtain a comprehensive understanding of assemblage dissimilarity and its implications for biodiversity conservation in the Himalayas, we explored the elevational patterns and determinants of beta diversity and its turnover and nestedness components of pairwise and multiple types and taxonomic and phylogenetic dimensions simultaneously. Patterns of beta diversity and their components of different types and dimensions were calculated based on 96 sampling quadrats along an 1800−5400 m elevational gradient. We examined whether and how these patterns differed from random expectations using null models. Furthermore, we used random forest methods to quantify the role of environmental variables representing climate, topography, and human disturbance in determining these patterns. We found that beta diversity and its turnover component, regardless of its types and dimensions, shown a hump-shaped elevational patterns. Both pairwise and multiple phylogenetic beta diversity were remarkably lower than their taxonomic counterpart. These patterns were significantly less than random expectation and were mostly associated with climate variables. In summary, our results suggested that assemblage dissimilarity of seed plants was mostly originate from the replacement of closely related species determined by climate-driven environmental filtering. Accordingly, conservation efforts should better cover elevations with different climate types to maximalize biodiversity conservation, rather than only focus on elevations with highest species richness. Our study demonstrated that comparisons of beta diversity of different types, dimensions, and components could be conductive to consensus on the origin and mechanism of assemblage dissimilarity.

Responses of plant diversity and soil microorganism diversity to nitrogen addition in the desert steppe, China

Nitrogen (N) deposition is a significant aspect of global change and poses a threat to terrestrial biodiversity. The impact of plant-soil microbe relationships to N deposition has recently attracted considerable attention. Soil microorganisms have been proven to provide nutrients for specific plant growth, especially in nutrient-poor desert steppe ecosystems. However, the effects of N deposition on plant soil microbial community interactions in such ecosystems remain poorly understood. To investigate these effects, we conducted a 6-year N-addition field experiment in a Stipa breviflora Griseb. desert steppe in Inner Mongolia Autonomous Region, northern China. Four N treatment levels (N0, N30, N50, and N100, corresponding to 0, 30, 50, and 100 kg N/(hm2•a), respectively) were applied to simulate atmospheric N deposition. The results showed that N deposition did not significantly affect the aboveground biomass of desert steppe plants. N deposition did not significantly reduce the alfa-diversity of plant and microbial communities in desert steppe, and low and mediate N additions (30 and 50 kg N/(hm2•a)) had a promoting effect on them. The variation pattern of plant Shannon index was consistent with that of the soil bacterial Chao1 index. N deposition significantly affected the beta-diversity of plants and soil bacteria, but did not significantly affect fungal communities. In conclusion, N deposition led to co-evolution between desert steppe plants and soil bacterial communities, while fungal communities exhibited strong stability and did not undergo significant changes. These findings help clarify atmospheric N deposition effects on the ecological health and function of the desert steppe.

Drivers of desert plant beta diversity on the Qinghai-Tibet plateau.

The desert ecosystem of the Qinghai-Tibet Plateau (QTP) is an important component of China's desert ecosystem. Studying the mechanisms shaping the taxonomic, phylogenetic, and functional beta diversity of plant communities in the QTP desert will help us to promote scientific conservation and management of the region's biodiversity. This study investigated the effects of environmental (including altitude, climate factors, and soil factors) and geographic distances on three facets of beta diversity as well as their turnover and nestedness components based on field survey data. The results showed that turnover components dominate the three facets of beta diversity. However, the turnover contributions to phylogenetic and functional beta diversity were lower than for taxonomic beta diversity. Environmental distance had a greater influence than geographic distance, with the former uniquely explaining 15.2%-22.8% of beta diversity and the latter explaining only 1.7%-2.4%. Additionally, the explanatory power of different factors for beta diversity differed between herbs and shrubs, with environmental distance being more important for the latter. Distance-based redundancy analysis suggested that soil total potassium content had a substantial impact on the beta diversity of three dimensions, with mean temperature of the coldest month and soil total phosphorus content having a substantial impact on taxonomic and functional beta diversity as well. Our results support that environmental sorting plays a predominant role in shaping plant community composition across QTP desert ecosystems. To maintain the plant diversity of this region, it is crucial to prioritize the conservation of its diverse environmental conditions and actively mitigate its degradation by anthropogenic pressures.

Effects of Spatial Resolution, Mapping Window Size, and Spectral Species Clustering on Remote Sensing of Plant Beta Diversity Using biodivMapR and Hyperspectral Imagery

AbstractUsing imaging spectroscopy (hyperspectral imaging), we assessed the effects of spatial resolution, size of mapping windows composed of pixels, and number of clustered spectral species on the capacity to map plant beta diversity using the biodivMapR package, in support of the planned NASA Surface Biology and Geology (SBG) satellite remote sensing mission. Specifically, we tested the ability of biodivMapR to distinguish natural communities among field‐verified locations. biodivMapR clusters pixels as spectral species used to calculate beta diversity among mapping windows composed of multiple pixels. We used NEON airborne 1 m resolution hyperspectral images collected at three sites representing native longleaf pine ecosystems in the southeastern U.S. and aggregated pixels to 1–90 m spatial resolution for comparative analyses. We also varied mapping window size using 30 m resolution images, commonly collected by satellite missions. The capacity to detect plant beta diversity decreased with coarser spatial resolution, which corresponded to fewer pixels per mapping window. Mapping window size in turn limited the spatial resolution of beta diversity maps composed of mapping windows. Assigning too few pixels per window, as well as assigning too many spectral species per image, results in overestimation of dissimilarity among locations representing the same community type and reduces the information content of beta diversity maps. These results demonstrate the advantage of maximizing spatial resolution of hyperspectral imaging instruments on the anticipated NASA SBG satellite mission and similar remote sensing projects, as well as the value of satellite‐borne hyperspectral imagers for mapping beta diversity worldwide.

Patterns of species richness and beta diversity of vascular plants along elevation gradient in Brazilian páramo

Patterns of species richness and beta diversity of vascular plants along elevation gradient in Brazilian páramo

Communities in infrastructure habitats are species rich but only partly support species associated with semi‐natural grasslands

Abstract Biodiversity linked to traditionally managed semi‐natural grasslands is declining, despite conservation efforts. At the same time, the area of novel grassland habitats along linear infrastructure, such as road verges and power line corridors, is increasing and in some regions surpass the area of semi‐natural grasslands. An open question is to what extent these novel grasslands can complement or even replace traditionally managed grasslands as habitat for grassland species. We compared the alpha (species richness) and beta (abundance‐based dissimilarities) diversity of plants, bumblebees and butterflies among semi‐natural pastures, verges of small and big roads, power line corridors and uncultivated field borders nested within 32 landscapes (2 × 2 km squares). Landscapes had either high or low road density and were with or without power line corridors. Across landscapes there was also a gradient in the area of semi‐natural pastures. Alpha diversity of all three species groups was as high in power line corridors and verges of small roads as in semi‐natural pastures, regardless of landscape composition. Although all habitat types shared a large proportion of species, community composition differed among habitats for all three species groups. The beta diversity of plants and butterflies was driven primarily by the replacement of species (turnover), while the beta diversity of bumblebees was driven by a rarer occurrence of certain species in road verges (nestedness). This means that linear infrastructure habitats cannot fully replace the role of semi‐natural grasslands for plant and pollinator diversity. The area of road verges, power line corridors and semi‐natural pastures in the landscape influenced community composition of plants and butterflies, but not the similarity in community composition among habitats within landscapes. Policy implications. Although novel grasslands along linear infrastructures have high numbers of grassland species, they only support a part of the biodiversity found in traditionally managed semi‐natural grasslands. Therefore, protecting and restoring semi‐natural grasslands should continue to be a priority for the conservation of grassland biodiversity. However, especially in landscapes where the area of semi‐natural grasslands is low, road verges and power line corridors can be important habitats for a number of grassland plants and insects and should be managed to promote biodiversity.

Beta diversity of urban spontaneous plants and its drivers in 9 major cities of Yunnan province, China

Urbanization has significantly reshaped regional biodiversity structure globally. Previous studies suggested that urban communities of spontaneous plants are well adapted to the urban environment. However, a perspective of urbanization that accounts for the joint impacts of the current state (as expressed by urbanization intensity) and the historical progress of urbanization (as expressed by urbanization rate) to reveal the mechanisms underlying the biodiversity patterns of spontaneous plants in cities is still lacking. Here we present data and analysis of spontaneous plants sampled in 709 patches within 82 sites of built-up areas from nine cities distributed across climatic and floristic zones in Yunnan province, a biodiversity hotspot in China. We used the exponent (z) of a species accumulation curve (SAC) model to characterize beta diversity among patches in a site, and found a higher beta diversity of native species compared with non-natives, indicating that the species composition of native plants is more heterogeneous. The beta diversity of all species groups was best explained by the constant c of the SAC (a proxy of alpha diversity), followed by the urbanization intensity (as expressed by the proportion of sealed surface and patches’ Shannon diversity index), and urbanization rate (as expressed by the sealed surface expansion rate). Moreover, beta diversity of non-native species was additionally negatively correlated with altitude. Our results suggest that the interplay of natural environmental factors and human-induced urbanization shape diversity of urban spontaneous plants in Yunnan province. Our findings emphasize that urban spontaneous plants diversity is not only a reflection of the current state of urbanization, but also a consequence of historical processes of urbanization.

Canopy Composition and Spatial Configuration Influences Beta Diversity in Temperate Regrowth Forests of Southeastern Australia

Structural features of the overstorey in managed and unmanaged forests can significantly influence plant community composition. Native Acacia species are common in temperate eucalypt forests in southeastern Australia. In these forests, intense disturbances, such as logging and wildfire, lead to high densities of regenerating trees, shrubs, and herbs. The tree layer is dominated by Acacia and Eucalyptus, that compete intensely for resources in the first decades after stand establishment. The relative abundance and size of Acacia and Eucalyptus varies widely due to stochastic factors such as dispersal, microsite variability, and weather and climatic conditions. This variability may influence the structure and composition of the herbaceous and shrub species. In the temperate forests of southeastern Australia, understorey plant diversity is assumed to be influenced by Acacia species density, rather than Eucalyptus density. To quantify the influence of Acacia and Eucalyptus density on plant community composition, we used remote sensing and machine learning methods to map canopy composition and then compare it to understorey composition. We combined unoccupied aerial vehicle (UAV or drone) imagery, supervised image classifications, and ground survey data of plant composition from post-logging regrowth forests in the Central Highlands of southeastern Australia. We found that aggregation and patch metrics of Eucalyptus and Acacia were strongly associated with understorey plant beta diversity. Increasing aggregation of Acacia and the number of Acacia patches had a significant negative effect on plant beta diversity, while the number of Eucalyptus patches had a positive influence. Our research demonstrates how accessible UAV remote sensing can be used to quantify variability in plant biodiversity in regrowth forests. This can help forest managers map patterns of plant diversity at the stand-scale and beyond to guide management activities across forested landscapes.

Compositional and phylogenetic beta diversity reveal different patterns of aquatic plant assemblages in lakes along the Changjiang River

Many articles have examined the aquatic flora in lakes along the Changjiang River over the past four decades. However, studies on taxonomic and phylogenetic alpha and beta diversity of aquatic plants along the Changjiang River are lacking. In order to clarify the distribution pattern of aquatic plants in lakes of the Changjiang River, we comprehensively analyzed the phylogenetic structure, compositional beta diversity (CBD), and phylogenetic beta diversity (PBD) of their aquatic plant assemblages. We found strong regional differences in phylogenetic community structures with significant differences in the net relatedness index and nearest taxon index values at subregional scales. Interestingly, similarity clustering based on compositional beta similarity showed that the lakes in the upper Changjiang River and upper Pearl River were clustered into a branch, and then connected with the lakes in the lower Changjiang River. However, similarity clustering based on phylogenetic beta similarity clustered the lakes in the upper and lower Changjiang River together into a branch, before connecting them with the lakes in the upper Pearl River. Additionally, we found significantly higher taxonomic dissimilarity than phylogenetic dissimilarity overall, as well as in individual subregions of the Changjiang River. These results suggested that the uplift of the Qinghai-Tibet Plateau and river capture played important roles in the aquatic plant assemblages of lakes resulting in patterns of geographic endemism at regional scales.

Understanding the taxonomic homogenization of road-influenced plant assemblages in the Qionglai mountain range: A functional and phylogenetic perspective.

As an increasingly prevalent form of human activity, roads drive the taxonomic homogenization of mountain plant assemblages, threatening global biodiversity. However, little is known about how mountain roads impact functional and phylogenetic beta diversity and how these effects are related to taxonomic homogenization. To understand the mechanism of taxonomic homogenization triggered by mountain roads, we used species absence/presence data from 76 plots (2 m*50 m) and values for 12 traits measured on 978 species from the interior and roadside communities in the Qionglai mountain range, one of the temperate regions with the highest plant species richness in the world. We used a structural equation modeling approach (SEM) to consider several surrogates of road disturbance (changes in soil physicochemical properties and the presence or absence of roads) and the causal relationship between three facets of beta diversity (taxonomic beta diversity, TBD; functional beta diversity, FBD and phylogenetic beta diversity, PBD). The results suggest that TBD, FBD and PBD respond inconsistently to mountain roads, despite strong positive correlations between the three facets of plant beta diversity in the study area. Compared with the interior community, the βtotal.tax and βtotal.func of the roadside community decreased by 2.54% and 2.22%, respectively, which were related to the reduction of species and trait richness differences and replacements; however, we did not find the same results when assessing the changes in βtotal.phy, which represents tip-weighted PBD (twPBD). Furthermore, the largest effect of roads on beta diversity was reflected in basal-weighted PBD (bwPBD), which decreased by 9.97%, indicating that those species with fewer extant relatives and longer evolutionary histories are more sensitive to mountain roads. Therefore, it is necessary to take targeted protection measures for ancient species in roadside communities. In addition, we believe that it is still necessary to take measures to prevent the further dispersal of nonnative species, although the presence of non-native species in roadside plots has led to small changes in three facets of beta diversity. There were causal relationships between the three facets of beta diversity, but their intensity and sign different in the SEM of different components of beta diversity (i.e., richness difference and replacement). Our findings suggest that the homogenization of community species composition at the landscape scale arises by a combination of adaptive responses of the functional traits of organisms to environmental consistency (e.g., reduced the differences in soil variables) caused by roads and resorting or reassembly of community clades composition due to environmental filtering. These results contribute to our comprehensive understanding of the impact of mountain roads on plant diversity, which highlights the complex relationship between human pressure and biodiversity loss.

Wind Power Increases the Plant Diversity of Temperate Grasslands but Decreases the Dominance of Palatable Plants

As an important clean energy source, the scale and quantity of wind power have steadily increased under the background of global change. The construction and operation of wind power facilities have massive impacts on grassland microclimates. However, the effect of wind power operation on the plant community composition is still unclear. To investigate this issue, we selected wind farms in 6 meadow grasslands and 6 typical steppes in the central region of Inner Mongolia, the province with the largest scale of grassland wind power operations in China. At these sites, we conducted field sample surveys to obtain species information, measure plant biomass, calculate plant diversity, and take soil samples to determine soil nutrients. The results showed that wind power operation significantly reduced the dominance of Poaceae and Cyperaceae plants in both types of grasslands and significantly increased the Shannon diversity of meadow grasslands. The inconsistent responses at each experimental site led to a nonsignificant overall effect of wind power operation on the plant beta diversity. In addition, wind power operation significantly increased plant biomass in meadow grasslands. Wind power operation did not change the soil total carbon, total nitrogen, ammonium nitrogen, or nitrate nitrogen. On the basis of the results, we suggest strengthening the long-term monitoring of temperate grassland plant community composition in wind farms, and replanting of community-building species could be done at appropriate times.

Could Purposefully Engineered Native Grassland Gardens Enhance Urban Insect Biodiversity?

Progress is required in response to how cities can support greater biodiversity. This calls for more research on how landscape designers can actively shape urban ecologies to deliver context-specific empirical bases for green space intervention decisions. Design experiments offer opportunities for implemented projects within real-world settings to serve as learning sites. This paper explores preliminary ecological outcomes from a multidisciplinary team on whether purposefully engineered native grassland gardens provide more habitat functions for insects than mainstream gardens in the City of Tshwane, South Africa. Six different sites were sampled: two recently installed native grassland garden interventions (young native), two contemporary non-native control gardens (young non-native) on the same premises and of the same ages as the interventions, one remnant of a more pristine native grassland reference area (old native), and one long-established, non-native reference garden (old non-native). Plant and insect diversity were sampled over one year. The short-term findings suggest that higher plant beta diversity (species turnover indicating heterogeneity in a site) supports greater insect richness and evenness in richness. Garden size, age, and connectivity were not clear factors mediating urban habitat enhancement. Based on the preliminary results, the researchers recommend high native grassland species composition and diversity, avoiding individual species dominance, but increasing beta diversity and functional types when selecting garden plants for urban insect biodiversity conservation in grassland biomes.

Plant beta-diversity across biomes captured by imaging spectroscopy

Monitoring the rapid and extensive changes in plant species distributions occurring worldwide requires large-scale, continuous and repeated biodiversity assessments. Imaging spectrometers are at the core of novel spaceborne sensor fleets designed for this task, but the degree to which they can capture plant species composition and diversity across ecosystems has yet to be determined. Here we use imaging spectroscopy and vegetation data collected by the National Ecological Observatory Network (NEON) to show that at the landscape level, spectral beta-diversity—calculated directly from spectral images—captures changes in plant species composition across all major biomes in the United States ranging from arctic tundra to tropical forests. At the local level, however, the relationship between spectral alpha- and plant alpha-diversity was positive only at sites with high canopy density and large plant-to-pixel size. Our study demonstrates that changes in plant species composition and diversity can be effectively and reliably assessed with imaging spectroscopy across terrestrial ecosystems at the beta-diversity scale—the spatial scale of spaceborne missions—paving the way for close-to-real-time biodiversity monitoring at the planetary level.

Ecological uniqueness and the determinants in arid desert ecosystems of Northwest China

Ecological uniqueness has important theoretical and practical significance for biodiversity conservation, and it has become a popular research topic in recent years. Species richness and soil nutrients play important roles in ecological uniqueness, but it is still unclear how different life forms, multiple biodiversity attributes, and environmental factors affect ecological uniqueness. In this study, we conducted a community investigation to combine species diversity, functional diversity, phylogenetic diversity, and soil factors to evaluate the impact of biotic and abiotic factors on ecological uniqueness. We verified these different relationships in woody and herbaceous plants. Our results showed that the species contribution to beta diversity (SCBD) of herbaceous plants was higher than that of other species, and SCBD had a strong correlation with species abundance and leaf thickness. Ecological uniqueness can be explained by soil factors and community characteristics, but the relative importance and interpretation of these characteristics differ between communities and between woody and herbaceous plants. Soil factors and community characteristics explained more of the ecological uniqueness in woody plants than herbaceous plants and communities. The community ecological uniqueness was mainly affected by soil pH. Soil moisture content and phylogenetic diversity had extremely significant positive effects on the ecological uniqueness of woody plants, while species richness and functional richness had significant negative effects. pH had a significant positive effect on the ecological uniqueness of herbaceous plants, and soil moisture indirectly affected the herb ecological uniqueness by affecting pH. In brief, the result showed that SCBD is significantly related to plant abundance, functional traits and leaf nutrients. In addition to focusing on sites with high species richness, functional diversity, and phylogenetic diversity, a comprehensive analysis from the perspective of different life forms can fully reflect the ecological uniqueness and proceed with species protection.

Influence of geographic distance and environmental factors on beta diversity of plants in the Alxa gobi region in northern China

Influence of geographic distance and environmental factors on beta diversity of plants in the Alxa gobi region in northern China

Plant beta diversity and its influence factors in the Liangshui National Nature Reserve in the central region of the Xiaoxing’an Mountains

Plant beta diversity and its influence factors in the Liangshui National Nature Reserve in the central region of the Xiaoxing’an Mountains

Horizontal and vertical variation in the structure of fruit‐feeding butterfly (Nymphalidae) assemblages in the Brazilian Cerrado

Abstract The Cerrado biome is a biodiversity hotspot with a rich biota, and intense anthropogenic pressures. Despite its importance, it is still poorly understood how insects occupy different spatial dimensions of the landscape. We investigated how the beta diversity of plants influences the beta diversity of nymphalids at the regional‐scale (gallery forest vs. savannah) and local‐scale (transects). We expected greater beta‐diversity in nymphalid assemblages in gallery forests given the heterogeneity of plants and canopy structure. We sampled nymphalids in each habitat monthly for 1 year and observed 3459 individuals from 62 species. Nymphalidae abundance was significantly higher in the understory than in the canopy. Specifically, only 18% of the individuals were captured in the canopy of gallery forests compared to 11% in savannah canopies. Species richness was higher in gallery forests (55 species) compared to savannahs (34 species). Savannah transects were very similar in plant species composition and butterfly assemblages within the understory and canopy, whereas the species composition of plants and butterflies in gallery forests was highly heterogeneous which is consistent with the habitat heterogeneity hypothesis. Gallery forests are spatially more complex, which probably results in higher niche availability that may contribute to reduce the community saturation and help to maintain greater beta diversity in these habitats.

Partitioned beta diversity patterns of plants across sharp and distinct boundaries of quartz habitat islands

AbstractQuestionsHabitat islands are often characterized by the presence of more or less sharp boundaries to adjacent matrix habitats. However, knowledge on boundaries of natural habitat islands is scarce, especially regarding patterns of beta diversity and its two underlying components: species turnover and nestedness. We therefore aim to quantify the effects of fine‐scaled and sharp boundaries of quartz islands (quartz gravel‐covered soils) on the different components of plant beta diversity and how they are linked to different soil environmental drivers.LocationKnersvlakte, Western Cape, South Africa.MethodsWe sampled plant species richness in 56 fine‐scale transects of 6 m × 1 m plots across eight different boundary types (four quartz island to matrix, four between habitats on quartz islands). Soil depth and chemistry (pH, electrical conductivity) were analyzed for each 1 m2 plot. Differences in the two beta diversity components (turnover and nestedness) for each boundary type were tested by t tests. We used linear models to test relationships between species and environmental dissimilarity.ResultsAll boundary types showed high beta diversity. Species turnover was the prevailing component for six boundary types, the nestedness component was only important for two boundary types. We found a significant linear increase of species dissimilarity with increasing dissimilarity in soil pH and distinct plant communities for the habitat types, but no significant increase for electrical conductivity or soil depth.ConclusionsThe spatial distinctiveness of the quartz islands leads to sharp boundaries, which result in high beta diversity, mainly through species turnover. This reflects the high levels of diversification and adaptation of the local plant communities. Nestedness occurred at two boundaries to the matrix, indicating that the latter does not necessarily represent an impermeable boundary for all species of the respective ecosystem. Studying diversity patterns across boundaries contributes to the question of applicability of island biogeography theory to habitat islands.

Beta diversity of plant community and soil mesofauna along an elevational gradient in a mountainous semi-arid oak forest

Community composition heterogeneity and its changes along environmental gradients are important aspects of landscape management and conservation. However, variations among different trophic levels are still poorly understood. This study aimed to evaluate the variability of beta diversity and its components (spatial turnover and nestedness) along an elevational gradient in two dominant exposures (north and south) for plants and mesofauna in a semi-arid oak forest in western Iran. Vegetation sampling was conducted in randomly distributed macro-plots (100 × 100 m2) in which the abundance of herbaceous and woody species was recorded using five plots of 2 × 2 m2 and three plots of 20 × 20 m2, respectively. Soil and litter samples were separately collected in each 20 × 20 m2 plot with a cylindrical soil extractor. The beta diversity of plant and mesofauna samples was additively separated into spatial turnover and nestedness, and these variables were regressed against elevation for each group. Compared to mesofauna, plant beta diversity and its components were more affected by topographic variables. Spatial turnover was the main driving mechanism of beta diversity in both mesofauna groups (soil vs. litter). In the case of plants, however, spatial turnover was also related to plant functional groups and topographic characteristics. Compared to mesofauna, plant diversity was more closely related to elevation although this relationship differed between functional groups. These results suggest that herbs are more sensitive to environmental gradients than mesofauna and can therefore be considered as sensitive indicators of environmental variations.