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Data from: Plant species richness and shrub cover attenuate drought effects on ecosystem functioning across Patagonian rangelands

Drought is an increasingly common phenomenon in drylands as a consequence of climate change. We used 311 sites across a broad range of environmental conditions in Patagonian rangelands to evaluate how drought severity and temperature (abiotic factors) and vegetation structure (biotic factors) modulate the impact of a drought event on the annual integral of normalized difference vegetation index (NDVI-I), our surrogate of ecosystem functioning. We found that NDVI-I decreases were larger with both increasing drought severity and temperature. Plant species richness (SR) and shrub cover (SC) attenuated the effects of drought on NDVI-I. Grass cover did not affect the impacts of drought on NDVI-I. Our results suggest that warming and species loss, two important imprints of global environmental change, could increase the vulnerability of Patagonian ecosystems to drought. Therefore, maintaining SR through appropriate grazing management can attenuate the adverse effects of climate change on ecosystem functioning.

Data from: Predicting spatial patterns of plant species richness: a comparison of direct macroecological and species stacking modelling approaches

PLEASE NOTE, THESE DATA ARE ALSO REFERRED TO IN TWO OTHER PUBLICATIONS. PLEASE SEE http://dx.doi.org/10.1111/j.1365-2486.2008.01766.x AND http://dx.doi.org/10.1111/2041-210X.12222 FOR MORE INFORMATION. Aim: This study compares the direct, macroecological approach (MEM) for modelling species richness (SR) with the more recent approach of stacking predictions from individual species distributions (S-SDM). We implemented both approaches on the same dataset and discuss their respective theoretical assumptions, strengths and drawbacks. We also tested how both approaches performed in reproducing observed patterns of SR along an elevational gradient. Location: Two study areas in the Alps of Switzerland. Methods: We implemented MEM by relating the species counts to environmental predictors with statistical models, assuming a Poisson distribution. S-SDM was implemented by modelling each species distribution individually and then stacking the obtained prediction maps in three different ways – summing binary predictions, summing random draws of binomial trials and summing predicted probabilities – to obtain a final species count. Results: The direct MEM approach yields nearly unbiased predictions centred around the observed mean values, but with a lower correlation between predictions and observations, than that achieved by the S-SDM approaches. This method also cannot provide any information on species identity and, thus, community composition. It does, however, accurately reproduce the hump-shaped pattern of SR observed along the elevational gradient. The S-SDM approach summing binary maps can predict individual species and thus communities, but tends to overpredict SR. The two other S-SDM approaches – the summed binomial trials based on predicted probabilities and summed predicted probabilities – do not overpredict richness, but they predict many competing end points of assembly or they lose the individual species predictions, respectively. Furthermore, all S-SDM approaches fail to appropriately reproduce the observed hump-shaped patterns of SR along the elevational gradient. Main conclusions: Macroecological approach and S-SDM have complementary strengths. We suggest that both could be used in combination to obtain better SR predictions by following the suggestion of constraining S-SDM by MEM predictions.

opencc-zeroJan 2020View details →

Current climate overrides historical effects on species richness and range size of freshwater plants in Europe and North America

1. The latitudinal diversity gradient (LDG) hypothesis suggests that species richness should be highest at low latitudes, whereas Rapoport's rule states that largest ranges ought to be found for species at high latitudes. However, there is no consensus over these patterns and their underlying drivers in the freshwater realm. 2. We investigated species richness and mean range size of freshwater plants in 50 km × 50 km grid cells across Europe (40°N to 71°N) and North America (25°N to 78°N), supplemented with data based on 1° latitudinal bands for mean range size. We were especially interested to find out whether there are similarities and differences in these ecogeographical patterns and their underlying drivers between the continents due to their contrasting historical characteristics, spatial extent and topography. 3. First, we used partial regression to reveal whether species richness and mean range size of freshwater plants have a linear or quadratic relationship with latitude. Second, we employed variation partitioning based on partial regression to model relationships between plant species richness and mean range size and four explanatory variable groups (i.e., environmental features, current climate, historical climate and geographical location). Third, we utilized boosted regression tree analysis to further investigate species richness and mean range size of freshwater plants in relation to a set of explanatory variables. 4. Our results revealed that species richness showed relatively similar patterns in relation to latitude between the continents. Similarly, mean range size trends were alike in North America whether we used 50 km x 50 km grid cell data or 1° latitudinal bands. Instead, different patterns in mean range size emerged between the used data sets in Europe. For both of species richness and mean range size, current climate (with different individual predictor variables) was the main driver in both the continents, but historical effects had a small influence on the response variables. 5. Synthesis. Our findings indicated that major ecogeographical rules can strongly vary for the same taxonomic group across broad scales between continents. It is also premature to rely solely on well-known terrestrial taxonomic groups when drawing generalizations about ecogeographical rules.

opencc-zeroDec 2010View details →

Data from: Fungal pathogen species richness: why do some plant species have more pathogens than others?

Variation among plant species in the number of associated herbivore and pathogen species is predicted to fit a species-area relationship in which the area or biomass embodied by a plant species is a function of individual size and geographic range size. This hypothesis is tested using published estimates of geographic range, individual size, and species richness of fungal-pathogens for 490 plant species occurring in the United States and controlling for sampling intensity and phylogenetic effects. The number of pathogens found on a plant species increases with the metrics of plant species' area and/or habitat diversity and their effects are similar between gymnosperm and angiosperm lineages. The strength of this pattern across a diverse set of plant lineages suggests that accumulation and persistence of pathogen species on plant species are governed by the same processes among temperate plants.

Data from: Plant species richness promotes soil carbon and nitrogen stocks in grasslands without legumes

1. The storage of carbon (C) and nitrogen (N) in soil are important ecosystem functions. Grassland biodiversity experiments have shown a positive effect of plant diversity on soil C and N storage. However, these experiments all included legumes, which constitute an important N input through N2-fixation. Indeed, the results of these experiments suggest that N2-fixation by legumes is a major driver of soil C and N storage. 2. We studied whether plant diversity affects soil C and N storage in the absence of legumes. In an 11-years grassland biodiversity experiment without legumes, we measured soil C and N stocks. We further determined above-ground biomass productivity, standing root biomass, soil organic matter decomposition and N mineralization rates to understand the mechanisms underlying the change in soil C and N stocks in relation to plant diversity and their feedbacks to plant productivity. 3. We found that soil C and N stocks increased by 18 and 16% in eight-species mixtures compared to the average of monocultures of the same species, respectively. Increased soil C and N stocks were mainly driven by increased C input and N retention, resulting from enhanced plant productivity, which surpassed enhanced C loss from decomposition. Importantly, higher soil C and N stocks were associated with enhanced soil N mineralization rates, which can explain the strengthening of the positive diversity-productivity relationship observed in the last years of the experiment. 4. Synthesis: We demonstrated that also in the absence of legumes plant species richness promotes soil carbon (C) and nitrogen (N) stocks via increased plant productivity. In turn, enhanced soil C and N stocks showed a positive feedback to plant productivity via enhanced N mineralization, which could further accelerate soil C and N storage in the long term.

Data from: Shrubs as ecosystem engineers across an environmental gradient: effects on species richness and exotic plant invasion

Ecosystem-engineering plants modify the physical environment and can increase species diversity and exotic species invasion. At the individual level, the effects of ecosystem engineers on other plants often become more positive in stressful environments. In this study, we investigated whether the community-level effects of ecosystem engineers also become stronger in more stressful environments. Using comparative and experimental approaches, we assessed the ability of a native shrub (Ericameria ericoides) to act as an ecosystem engineer across a stress gradient in a coastal dune in northern California, USA. We found increased coarse organic matter and lower wind speeds within shrub patches. Growth of a dominant invasive grass (Bromus diandrus) was facilitated both by aboveground shrub biomass and by growing in soil taken from shrub patches. Experimental removal of shrubs negatively affected species most associated with shrubs and positively affected species most often found outside of shrubs. Counter to the stress-gradient hypothesis, the effects of shrubs on the physical environment and individual plant growth did not increase across the established stress gradient at this site. At the community level, shrub patches increased beta diversity, and contained greater rarified richness and exotic plant cover than shrub-free patches. Shrub effects on rarified richness increased with environmental stress, but effects on exotic cover and beta diversity did not. Our study provides evidence for the community-level effects of shrubs as ecosystem engineers in this system, but shows that these effects do not necessarily become stronger in more stressful environments.

opencc-zeroDec 2017View details →

Data from: Persistence at the final stage of volcanic island ontogeny: abiotic predictors explain native plant species richness on 111 remote Pacific atolls

Aim: The final island ontogeny of the General Dynamic Model (GDM) (i.e. before island submergence) in tropical oceans corresponds to the coral atoll stage. Here, we examined whether the species richness of native vascular plants (indigenous and endemic species) on atolls is controlled by spatial and/or physical processes. We also predicted that atolls strongly affected by anthropogenic disturbance would have lower native species richness than predicted by spatial and physical processes. Location: Marshall Islands, Kiribati Islands, Nauru, Niue, Johnston, Cook Islands, French Polynesia and Pitcairn Islands (Pacific Ocean). Taxon: Native vascular plants Methods: We used stepwise regression to test the relative influence of five biogeographic variables on native species richness. Relationships were assessed for the full set of 111 Pacific coral atolls, as well as for atoll subsets ranging from 9 to 45 atolls. An index of human impact was then estimated, and residuals in the regression model predicting species richness from biogeographic variables were compared with the level of human impact. Results: A regression model including atoll area, highest atoll elevation, the stepping stone distances from the nearest raised atoll and volcanic island explained native species richness on the 111 Pacific coral atolls. Regression models for different archipelagos and atoll subsets were also significant. Endemic species richness was significantly linked with highest atoll elevation and the stepping stone distances from the nearest raised atoll. Residuals in the biogeographic regression model were barely related to human impact across the 111 atolls but were significantly related to human impact in the Kiribati atolls. Main conclusions: Native species richness on atolls is mainly controlled by physical and spatial characteristics. However, anthropogenic disturbances have altered the predicted pattern of native species richness leading to a lower model fit in some atoll subsets.

opencc-zeroMay 2019View details →

Data from: Habitat diversity associated with island size and environmental filtering control the species richness of rock-savanna plants in neotropical inselbergs

Disentangling the multiple factors controlling species diversity is a major challenge in ecology. Island biogeography and environmental filtering are two influential theories emphasizing respectively island size and isolation, and the abiotic environment, as key drivers of species richness. However, few attempts have been made to quantify their relative importance and investigate their mechanistic basis. Here, we applied structural equation modelling, a powerful method allowing test of complex hypotheses involving multiple and indirect effects, on an island-like system of 22 French Guianan neotropical inselbergs covered with rock-savanna. We separated the effects of size (rock-savanna area), isolation (density of surrounding inselbergs), environmental filtering (rainfall, altitude) and dispersal filtering (forest-matrix openness) on the species richness of all plants and of various ecological groups (terrestrial versus epiphytic, small-scale versus large-scale dispersal species). We showed that the species richness of all plants and terrestrial species was mainly explained by the size of rock-savanna vegetation patches, with increasing richness associated with higher rock-savanna area, while inselberg isolation and forest-matrix openness had no measurable effect. This size effect was mediated by an increase in terrestrial-habitat diversity, even after accounting for increased sampling effort. The richness of epiphytic species was mainly explained by environmental filtering, with a positive effect of rainfall and altitude, but also by a positive size effect mediated by enhanced woody-plant species richness. Inselberg size and environmental filtering both explained the richness of small-scale and large-scale dispersal species, but these ecological groups responded in opposite directions to altitude and rainfall, that is positively for large-scale and negatively for small-scale dispersal species. Our study revealed both habitat diversity associated with island size and environmental filtering as major drivers of neotropical inselberg plant diversity and showed the importance of plant species growth form and dispersal ability to explain the relative importance of each driver.

opencc-by-4.0Nov 2023View details →

Dataset and code for the manuscript "Plant indirect interactions reduce species richness but increase phylogenetic diversity"

This Zenodo repository contains the original data set and code for replicating the result published in the paper "Plant indirect interactions reduce species richness but increase phylogenetic diversity" <ol><li>The "BD.xlsx" data frame contains the original data. The first column, "ID," is an ID for each one of the patches (i.e., vegetation units containing one or more individuals for the same or different species separated from other patches by bare ground). The second and third columns, "localidad" and "suelo", inform about the location where patches are found. The "species" column identifies the different species present at each patch.</li><li> The "Comb1.xlsx" data frame contains the possible combination of 4 species for each ID (concatenation of "localidad" and "suelo") for all the species found in the sampling. Besides "ID", there is one column for each of the species included in interactions ("spA", "spB", "spC", "spD") that contains the name of the species.</li><li>The "phylo.xlsx" data frame contains the taxonomic information of the species found during the sampling. For each species recorded in column "species" we assign its genus (column "genus") and family (column "family")</li><li>  "ALL_IN.xlsx" is a data frame containing for each "ID" (proxy of location), the species involved in interactions ("spA", "spB", "spC" & "spD"), the "interaction sign" indicating if a given interaction is positive or negative (results based on simulation) and "Order" indicating the number of species involved in the interactions(from two to four).</li><li>"Code.R" provides the R code necessary to obtain the results. As statistics is based on simulation, every run can provide slightly different results, although differences do not affect interpretation. Please note that running time can be elevated depending on the computer used.</li></ol>

opencc-zeroJan 2022View details →

Changes in plant species richness due to land use and nitrogen deposition across the globe

Data and scripts corresponding to the article "Combined effects of land use and nitrogen deposition on plant species richness worldwide". In the article, we quantified the combined effects of land use and nitrogen deposition on terrestrial plant species richness at a 0.25º spatial resolution across the globe. We first determined the proportional changes in plant species richness for different land-use types and N deposition values through meta-analyses of local monitoring data obtained from the literature. We then combined the site-level responses with global land use and N deposition maps in a new multi-pressure species-area relationship (mp-SAR) model to provide estimates of changes in plant species richness at a resolution of 0.25º (about 25 km at the equator) worldwide. In this repository you will find all the data necessary to get the final results and the code in R to guide you through out the analysis.

opencc-zeroOct 2022View details →

Key roles for the freezing line and disturbance in driving the low plant species richness of temperate regions

Aim: At the macroscale, climate strongly correlates with species richness gradients, resulting from differences in in-situ diversification and dispersal. One historical explanation for the pattern is that regions spanning temperate climates contain few species because past disturbances have generated high extinction rates, and species from tropical regions are unable to easily colonize temperate regions. We test these postulates for Himalayan plants, which span subtropical to temperate climates over steep elevational gradients. Location: Himalaya Time period: Present day Major taxa studied: Angiosperms Methods: We use a comprehensive survey of 31 floras to document the elevational and geographical distributions of native Himalayan plants, augmented by field studies of trees in both the east and west Himalaya. We use grade of membership models to cluster species according to locations shared and phylogenetic analysis to evaluate diversification rates. Results: Species fall into four cohesive biotas, organized by climate. Points of turnover between biotas occur where the mean minimum temperature of the coldest month is approximately 0oC (2,000 m - 2,500 m), and at the point of occasional annual freezing (1,000 m - 1,500 m); these boundaries run the length of the Himalaya. The patterns are retained when we consider whole clades rather than species. All plants (and the subsets trees, herbs and shrubs) belonging to the biota above the 2,000 m - 2,500 m line have higher recent speciation rates than those lower down. Main conclusions: We attribute the high rate of recent speciation in temperate climates to high rates of turnover, creating ecological and geographical opportunity. The high elevation biota has few species, but spans the largest area, implying species numbers are far from any carrying capacity, at least with respect to accumulation of allopatric forms. This study thus links climatic restrictions of clades to differences in diversification rates, and by inference species numbers.

opencc-zeroApr 2022View details →

Microbial community from species rich meadow supports plant specialists during meadow restoration

Soil properties and soil microbial communities can greatly affect plant communities, especially in disturbed ecosystems. However, their relative contribution to the final effect on plants has rarely been assessed. We manipulated the soil microbial community in microcosms by inoculating sterilized soils originating from preserved species-rich meadow and a restored meadow with a high and low diversity of microbial inoculum (manipulated by dilution of microbial community extract) from those soils in full factorial manner, yielding eight treatments (2 soil origins × 2 inoculum sources × 2 levels of inoculum diversity). In general, the biomass of plant meadow specialists (Filipendula vulgaris, Phleum phleoides, and Prunella grandiflora) was greater with the preserved meadow inoculum than with the restored meadow inoculum but tended to be greater in the restored meadow soil than in the preserved meadow soil. Two meadow generalists (Festuca rubra, and Centaurea jacea) were not significantly affected by soil origin, inoculum source, or inoculum diversity, but third generalist Plantago media produced greater biomass in the preserved meadow soil than in the restored meadow soil. Total aboveground biomass was not affected by the treatments, but total belowground biomass was greater with microbial inoculum from the preserved meadow than from the restored meadow, and this increase was greater in the restored meadow soil than in the preserved meadow soil. Our results indicate strong responses of the preserved meadow specialists to the soil microbial community, which may explain why they are rare in the meadows that were restored following agricultural use.

opencc-zeroApr 2022View details →

Richness, not evenness, of invasive plant species promotes invasion success into native plant communities via selection effects

Native plant communities are often invaded by multiple alien species. It is still unclear how increasing diversity of alien invasive species suppresses the growth of native species and thus contributes to invasion success. In the subtropical monsoon region of Southeast China, we experimentally created a native plant community with 18 herbaceous species. One week later, we let it be invaded by either zero (controls without invasion), one, two, four or eight alien plant species, with either high or low species evenness. After a four-month growth period we harvested the aboveground biomass of each species. We found that increasing invasive species richness significantly increased invasive plant biomass, the biomass of all invasive and native plant species within the community, and invasion success (the ratio of invasive plant biomass to the biomass of all native and invasive plants), but it did not significantly reduce native plant biomass. Experimentally manipulating invasive species evenness did not influence invasion success and did not show any differential suppression effects on native plants. One invasive species, Sesbania cannabina, became dominant in terms of plant biomass, irrespective of its proportion in the alien plant mixtures. Throughout this experiment, effects of invasive species richness on invasion success were mainly due to such selection effects among the invasive species. On the other hand, the unchanged biomass of native species under increasing invasive plant richness suggests the presence of at least partly complementary resource niches between invasive and native species.

opencc-zeroSep 2022View details →

Data from: Plant species richness and sunlight exposure increase pollinator attraction to pollinator gardens

Evidence documenting the decline of insect populations is accumulating. Efforts have increased to mitigate pollinator losses by establishing gardens to support pollinator diversity. However, knowledge of the specific garden characteristics, landscape features and environmental factors that affect pollinator diversity and abundance is limited, particularly in biodiverse regions in North America. In order to better understand how garden characteristics affect pollinator attraction, we compared pollinator composition across 16 pollinator gardens in the Appalachian ecoregion in North America. We evaluated the effects of garden characteristics (e.g., plant richness, flower abundance, garden size, proportion of native species), landscape features (land-use type, distance to forest) and environmental factors (sunlight exposure) on pollinator richness, overall visitation rate and visitation rate by defined pollinator groups (i.e., solitary native bees, bumblebees, honeybees, lepidopterans and other insects). Solitary bees (i.e., native bees besides Bombus) were the most frequent visitors (61%). We found differences in pollinator species composition between urban and rural gardens. Moreover, plant richness had a positive effect on pollinator richness and an increase in flower abundance increased pollinator visitation rate. Flower abundance, plant richness and high sunlight exposure increased visitation rate of solitary bees. Visitation rate of solitary bees however, decreased with increasing proportion of native plants. Overall, our results indicate that garden characteristics, landscape and environmental factors all are important mediators of pollinator diversity and abundance. Solitary bees were most affected by garden (i.e., plant richness, number of flowers, proportion of native plants) and environmental factors (i.e., sunlight exposure). However, we also identified differential effects of garden and environmental factors across pollinator groups. We suggest that an integrated management approach that considers multiple garden and environmental characteristics could help improve the effectiveness of pollinator garden as a conservation tool and help preserve this key ecosystem service.

opencc-zeroDec 2018View details →

Data from: The species richness pattern of vascular plants along a tropical elevational gradient and the test of elevational Rapoport's rule depend on different life‐forms and phytogeographic affinities

The research about species richness pattern and elevational Rapoport's rule (ERR) have been carried out mostly in the temperate regions in the recent years and scarcely in the tropical mountains; meanwhile, it is unclear whether the ERR is consistent among different life‐forms and phytogeographic affinities. Here, we compiled a database of plant species of Mount Kenya, a tropical mountain of East Africa, and divided these species into twelve groups depending on the life‐form and phytogeographic affinity of each species. We inspected the species richness pattern of each group along the elevation gradient and also tested ERR of each group using Stevens' method. Our results showed that species richness of the total species showed a positively skewed (hump‐shaped) pattern along the elevation gradient and different life‐forms and phytogeographic affinities showed similar hump‐shaped patterns as the total species. The average elevation range size of the total species and herbaceous species showed increasing patterns along the elevation gradient, while lycophytes and ferns, and woody species showed an obvious downward trend after peaking in the high elevation regions. We concluded that the widely distributed herbaceous species which also have broad elevation range sizes are more applicable to ERR, while the narrowly distributed woody species with small elevation range sizes occurring in the higher elevations could reverse ERR. Therefore, we concluded that the ERR is not consistent among different organisms in the same region.

opencc-zeroDec 2015View details →

Data from: Plant species richness negatively affects root decomposition in grasslands

Plant diversity enhances many ecosystem functions, including root biomass production, which drives soil carbon input. Although root decomposition accounts for a large proportion of carbon input for soil, little is known about plant diversity effect on this process. Plant diversity may affect root decomposition in two non-exclusive ways: by providing roots of different substrate quality (e.g. root chemistry) and/or by altering the soil environment (e.g. microclimate). To disentangle these two pathways, we conducted three decomposition experiments using a litter-bag approach in a grassland biodiversity experiment. We hypothesized that: (i) plant species richness negatively affects substrate quality (indicated by increased C:N ratios), which we tested by decomposing roots collected from each experimental plot in one common plot; (ii) plant species richness positively affects soil environment (indicated by increased soil water content), which we tested by decomposing standardized roots in all experimental plots; (iii) the overall effect of plant species richness on root decomposition, due to the contrast between quality and environmental effects, is neutral, which we tested by decomposing community roots in their 'home' plots. Plant species richness negatively affected root decomposition in all three experiments. The negative effect of plant species richness on substrate quality was largely explained by increased root C:N ratios along the diversity gradient. Functional group presence explained more variance in substrate quality than species richness. Here, the presence of grasses negatively affected substrate quality and root C:N ratios, while the presence of legumes and small herbs had positive effects. Plant species richness had a negative effect on soil environment despite its positive effect on soil water content which is known to stimulate decomposition. We argue that – instead of soil water content – a combined effect of soil temperature and seasonality might drive environmental effect of plant diversity on decomposition in our plant communities, but this remains to be tested. Synthesis. Our results demonstrate that both substrate quality and soil environment contribute to the net negative effect of plant diversity on root decomposition. This study promotes our mechanistic understanding of increased soil carbon accumulation in more diverse grassland plant communities.

Figure 2 in Multi-scale patterns in the host specificity of plant-dwelling arthropods: the influence of host plant and temporal variation on species richness and assemblage composition of true bugs (Hemiptera)

Figure 2. Non-metric multi-dimensional scaling (MDS) ordination showing hemipteran composition for all sampling periods with selected plant species superimposed.

Figure 5 in Multi-scale patterns in the host specificity of plant-dwelling arthropods: the influence of host plant and temporal variation on species richness and assemblage composition of true bugs (Hemiptera)

Figure 5. Annual cyclic pattern of the proportion of the effectively specialized fauna (squares) and singleton species (circles) for the total number of hemipteran species from each sampling period.

Figure 3 in Multi-scale patterns in the host specificity of plant-dwelling arthropods: the influence of host plant and temporal variation on species richness and assemblage composition of true bugs (Hemiptera)

Figure 3. Mean number of individuals (from SIMPER analysis) of dominant hemipteran species, during each sampling period, for most plant species.

Figure 1 in Multi-scale patterns in the host specificity of plant-dwelling arthropods: the influence of host plant and temporal variation on species richness and assemblage composition of true bugs (Hemiptera)

Figure 1. Interactions between plant species sampled and sampling period for (A) abundance (number of individuals) per plant and (B) species richness per plant (standard error bars are shown).