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opencc-zeroDec 2014View details →

Data from: Bacterial diversity amplifies nutrient-based plant-soil feedbacks

Plants foster diverse assemblages of bacteria in the rhizosphere serving important functions which may result in enhanced plant growth. Microbial diversity is increasingly recognized to shape the functionality of microbial communities. This leads to the assumption that there is a positive relationship between rhizosphere diversity and plant growth. Here we investigate how bacterial diversity affects the mineralization of organic matter and plant nutrient acquisition. We hypothesized that altered bacterial diversity will affect nitrogen mineralisation, uptake by plants and ultimately plant growth. We set up a controlled model system with Arabidopsis thaliana colonized by defined assemblages of fluorescent pseudomonads, a well-characterised plant-beneficial rhizosphere taxon. The growth substrate contained casein as sole nitrogen source, making the plant nitrogen uptake dependant on breakdown by bacterial enzymes. Bacterial diversity was associated with a higher enzyme activity which increased nitrogen mineralization and enhanced plant growth. The effect of bacterial diversity on plant growth increased with time, pointing to a positive feedback between bacteria and plants: Bigger plants associated with species-rich bacterial communities supported more bacterial growth, which further enhanced the impact of bacteria on plant growth. We demonstrate that plant-soil feedbacks establish rapidly during one single growth season and that bacterial diversity modulates this interaction. Preserving soil microbial diversity therefore may improve positive plant-soil feedbacks and thereby plant growth.

opencc-zeroDec 2018View details →

Data from: SRUD: a simple non-destructive method for accurate quantification of plant diversity dynamics

1. Predicting changes in plant diversity in response to human activities represents one of the major challenges facing ecologists and land managers striving for sustainable ecosystem management. Classical field studies have emphasized the importance of community primary productivity in regulating changes in plant species richness. However, experimental studies have yielded inconsistent empirical evidence, suggesting that primary productivity is not the sole determinant of plant diversity. Recent work has shown that more accurate predictions of changes in species diversity can be achieved by combining measures of species' cover and height into an index of Space Resource Utilization (SRU). While the SRU approach provides reliable predictions, it is time-consuming and requires extensive taxonomic expertise. Ecosystem processes and plant community structure are likely driven primarily by dominant species (mass-ratio effect). Within communities, it is likely that dominant and rare species have opposite contributions to overall biodiversity trends. We therefore suggest that better species richness predictions can be achieved by utilizing SRU assessments of only the dominant species (SRUD), as compared to SRU or biomass of the entire community. 2. Here, we assess the ability of these measures to predict changes in plant diversity as driven by nutrient addition and herbivore exclusion. First, we tested our hypotheses by carrying out a detailed analysis in an alpine grassland that measured all species within the community. Next, we assessed the broader applicability of our approach by measuring the first three dominant species for five additional experimental grassland sites across a wide geographic and habitat range. 3. We show that SRUD outperforms community biomass, as well as community SRU, in predicting biodiversity dynamics in response to nutrients and herbivores in an alpine grassland. Across our additional sites, SRUD yielded far better predictions of changes in species richness than community biomass, demonstrating the robustness and generalizable nature of this approach. 4. Synthesis. The SRUD approach provides a simple, non-destructive and more accurate means to monitor and predict the impact of global change drivers and management interventions on plant communities, thereby facilitating efforts to maintain and recover plant diversity.

opencc-zeroDec 2013View details →

Data from: Partner diversity and identity impacts on plant productivity in Acacia-rhizobial interactions

1.Genetic variation for functionally important traits is ubiquitous in communities of nitrogen-fixing rhizobia, and while some studies have described significant effects of diversity on the functioning of plant-associated microbial communities, we lack a systematic test of how rhizobial diversity influences plant productivity. 2. The complexity of potential interactions among rhizobia and plants complicates the development of general predictions regarding causal relationships between rhizobial diversity and plant productivity. For example, while rhizobial complementarity may result in positive associations between symbiont diversity and plant productivity, antagonistic competition may reduce rhizobial community function. 3. Using two widespread native Australian Acacia species (A. salicina, A. stenophylla) and experimental rhizobial communities derived from 16 bacterial genotypes naturally associated with these hosts, we examined how the provision of mutualistic benefit varies with rhizobial identity, diversity and phylogenetic relatedness. 4. Analysis of plant performance in relation to rhizobial genotypic richness revealed that the presence of multiple rhizobial genotypes in the rhizosphere was associated with a general decrease in plant productivity compared to growth with single rhizobial genotypes. Importantly, these results appear to be robust in the face of variation in host identity and host diversity (i.e. one or two species mixtures). We also found that rhizobial genotypic identity and host species significantly influenced plant productivity in Acacia-rhizobia interactions, both in single and multi-strain inoculations. 5. Synthesis. Together, our data show that multiple rhizobia interacting with a single host species creates opportunities for emergent or higher-order effects that extend beyond those that could be simply predicted based upon outcomes of pairwise interactions, and that increased mutualist diversity does not necessarily translate into positive effects on plant growth.

opencc-zeroDec 2018View details →

Data from: Interactions between functionally diverse fungal mutualists inconsistently affect plant performance and competition

Plants form mutualistic relationship with a variety of belowground fungal species. Such a mutualistic relationship can enhance plant growth and resistance to pathogens. Yet, we know little about how interactions between functionally diverse groups of fungal mutualists affect plant performance and competition. We experimentally determined the effects of interaction between two functional groups of belowground fungi that form mutualistic relationship with plants, arbuscular mycorrhizal (AM) fungi and Trichoderma, on interspecific competition between pairs of closely related plant species from four different genera. We hypothesized that the combination of two functionally diverse belowground fungal species would allow plants and fungi to partition their symbiotic relationships and relax plant‐plant competition. Our results show that: 1) the AM fungal species consistently outcompeted the Trichoderma species independent of plant combinations; 2) the fungal species generally had limited effects on competitive interactions between plants; 3) however, the combination of fungal species relaxed interspecific competition in one of the four instances of plant–plant competition, despite the general competitive superiority of AM fungi over Trichoderma. We highlight that the competitive outcome between functionally diverse fungal species may show high consistency across a broad range of host plants and their combinations. However, despite this consistent competitive hierarchy, the consequences of their interaction for plant performance and competition can strongly vary among plant communities.

opencc-zeroDec 2015View details →

Data from: Phylogenetic diversity is maintained despite richness losses over time in restored tallgrass prairie plant communities

Ecosystem restoration is an important tool for mitigating biodiversity loss and recovering critical ecosystem services to humanity, but restoration rarely takes into account the evolutionary attributes of the community being restored. Phylogenetic diversity (PD) represents a potentially valuable measure of restoration success because it can correlate with functional trait diversity that drives ecosystem function. However, PD patterns in restored communities are rarely assessed. We surveyed plant communities in restored tallgrass prairies 2–19 years old and calculated two PD measures, SESMNTD and SESMPD, of the communities and seed mixture applied to sites. We also identified high-threat exotic species present in each site to determine whether PD of the seed mixture applied was related to resistance against invasion. We show that PD in North American tallgrass prairie restorations, as measured by both SESMNTD and SESMPD, is maintained over time even as richness declines. Neither the resulting community PD nor invasion by high-threat exotic species was affected by PD of the seed mixture used in site restoration. Thus, simply maximizing PD of seed mixtures without considering the particular component species is unlikely to help achieve restoration goals. Synthesis and applications. These results suggest that species losses over time are not biased towards species with or without close relatives in the community. If phylogenetic diversity (PD) reflects functional trait diversity in communities, then local declines in species richness may not necessarily mean the loss of ecosystem function in restoration projects. However, PD of restored communities may be limited by low establishment rates for most species. Conservation practitioners should consider PD with careful planning to maintain overall community diversity and potentially maximize ecosystem function and services in restorations. This perspective will require a deeper understanding of the relationships between phylogenetic relatedness and traits associated with competition and fitness.

opencc-zeroDec 2012View details →

Data from: Invasive plants have scale-dependent effects on diversity by altering species-area relationships

Although invasive plant species often reduce diversity, they rarely cause plant extinctions. We surveyed paired invaded and uninvaded plant communities from three biomes. We reconcile the discrepancy in diversity loss from invaders by showing that invaded communities have lower local richness but steeper species accumulation with area than that of uninvaded communities, leading to proportionately fewer species loss at broader spatial scales. We show that invaders drive scale-dependent biodiversity loss through strong neutral sampling effects on the number of individuals in a community. We also show that nonneutral species extirpations are due to a proportionately larger effect of invaders on common species, suggesting that rare species are buffered against extinction. Our study provides a synthetic perspective on the threat of invasions to biodiversity loss across spatial scales.

Fig. 9 in Phytochemical and biological studies on rare and endangered plants endemic to China. Part XXII. Structurally diverse diterpenoids from the leaves and twigs of the endangered conifer Torreya jackii and their bioactivities

Fig. 9. Experimental ECD spectra of 5 and 6 in MeCN.

Fig. 7. Proposed biosynthetic relationships between compounds 7 and 1–3 in Phytochemical and biological studies on rare and endangered plants endemic to China. Part XXII. Structurally diverse diterpenoids from the leaves and twigs of the endangered conifer Torreya jackii and their bioactivities

Fig. 7. Proposed biosynthetic relationships between compounds 7 and 1–3.

Fig. 4 in Phytochemical and biological studies on rare and endangered plants endemic to China. Part XXII. Structurally diverse diterpenoids from the leaves and twigs of the endangered conifer Torreya jackii and their bioactivities

Fig. 4. ORTEP drawing of 1.

Fig. 5 in Phytochemical and biological studies on rare and endangered plants endemic to China. Part XXII. Structurally diverse diterpenoids from the leaves and twigs of the endangered conifer Torreya jackii and their bioactivities

Fig. 5. Experimental and calculated ECD spectra of 2 in MeCN.

Fig. 2. 1H–1H in Phytochemical and biological studies on rare and endangered plants endemic to China. Part XXII. Structurally diverse diterpenoids from the leaves and twigs of the endangered conifer Torreya jackii and their bioactivities

Fig. 2. 1H–1H COSY (for 2–4, and 6) and selected HMBC correlations (for 1–6).

Fig. 3 in Phytochemical and biological studies on rare and endangered plants endemic to China. Part XXII. Structurally diverse diterpenoids from the leaves and twigs of the endangered conifer Torreya jackii and their bioactivities

Fig. 3. Key NOE correlations of 1–6.

Fig. 1 in Phytochemical and biological studies on rare and endangered plants endemic to China. Part XXII. Structurally diverse diterpenoids from the leaves and twigs of the endangered conifer Torreya jackii and their bioactivities

Fig. 1. Chemical structures of 1–21.

Fig. 8 in Phytochemical and biological studies on rare and endangered plants endemic to China. Part XXII. Structurally diverse diterpenoids from the leaves and twigs of the endangered conifer Torreya jackii and their bioactivities

Fig. 8. Experimental and calculated ECD spectra of 4 in MeCN.

Fig. 6 in Phytochemical and biological studies on rare and endangered plants endemic to China. Part XXII. Structurally diverse diterpenoids from the leaves and twigs of the endangered conifer Torreya jackii and their bioactivities

Fig. 6. Experimental and calculated ECD spectra of 3 in MeCN.

opencc-zeroNov 2021View details →

Global synthesis of effects of plant species diversity on trophic groups and interactions

Numerous studies have demonstrated that plant species diversity enhances ecosystem functioning in terrestrial ecosystems, including diversity effects on insects (herbivores, predators and parasitoids) and plants. However, the effects of increased plant diversity across trophic levels in different ecosystems and biomes have not yet been explored on a global scale. Through a global meta-analysis of 2,914 observations from 351 studies, we found that increased plant species richness reduced herbivore abundance and damage but increased predator and parasitoid abundance, predation, parasitism and overall plant performance. Moreover, increased predator/parasitoid performance was correlated with reduced herbivore abundance and enhanced plant performance. We conclude that increasing plant species diversity promotes beneficial trophic interactions between insects and plants, ultimately contributing to increased ecosystem services.

opencc-zeroDec 2021View details →

Local plant richness predicts bee abundance and diversity in a study of urban residential yards

Understanding the drivers of biodiversity in cities is a central goal of urban ecology. There is currently intense scientific and public interest in the factors that influence pollinator diversity in cities and their surroundings. Existing studies point to a variety of landscape and local factors as potentially important, including urbanization (often defined as impervious surface cover in the surrounding lands), tree canopy cover and the diversity and abundance of locally flowering plants. However, few studies have sought to weigh the relative importance of these predictors of bee community metrics. Using a set of 27 residential yards chosen to represent a gradient of both urbanization and tree canopy cover at a landscape scale, we used pan trapping and netting to assess the abundance and diversity of local bee communities across the City of Ottawa, Ontario, Canada. Surprisingly, the landscape factors (urbanization and tree cover) described only a tiny fraction (< 1%) of the total variance in bee abundance and diversity across sites. This was true regardless of the scale of analysis at which the landscape factors were measured. Instead, a yard's floral richness, and, to a somewhat lesser extent, its floral abundance, emerged as the most important predictors of a yard's bee community abundance and diversity. Our study offers an important counterpoint to a growing body of work emphasizing the impacts of landscape factors on bee communities. Instead, our research suggests that improving bee floral resources by increasing the plant species richness and abundance locally is a powerful tool to support bee conservation, regardless of the level of urbanization or tree cover in the surrounding landscape. Our work highlights that the practice of promoting 'bee-friendly' plantings in private yards, currently being undertaken by a number of non-profits around the world, can play an important role in restoring and maintaining urban pollinator communities.

opencc-zeroJan 2022View details →

Genetic diversity of Horsfieldia tetratepala (Myristicaceae), an endangered plant species with extremely small populations to China: implications for its conservation

Genetic variation determines the evolutionary potential of a species and is vital for fully understanding the evolution of a species, as well as for developing optimal conservation strategies. Horsfieldia tetratepala is an economically important rainforest tree which has declined steadily, mainly though habitat destruction, and an endangered, narrow endemic in China where it is also classified as a Plant Species with Extremely Small Populations (PSESP). Effective conservation strategies for H. tetratepala are required urgently, but limited information about its genome is available. Accordingly, restriction site-associated DNA sequencing (RAD_seq) was used to sequence sixty-three H. tetratepala trees covering ten isolated populations to assess genome-level diversity and population structure, generating 8,103 high-quality SNPs. Low genetic diversity and moderate genetic differentiation was observed among populations, but Bayesian clustering divided the sampled H. tetratepala populations into two genetic clusters, though with some populations from Guangxi and Yunnan intermixed. Because of increasing of habitat fragmentation and human disturbance, conservation priority should be placed on populations with higher genetic variation (e.g., BB, TKH, DWS, and GLQ). Overall, our study provides valuable genomic resources for H. tetratepala that will significantly advance the formulation of effective conservation strategies.

opencc-zeroJan 2022View details →

Plant community impact on productivity: trait diversity or key(stone) species effects?

Outside controlled experimental plots, the impact of community attributes on primary productivity has rarely been compared to that of individual species. Here, we identified plant species of high importance for productivity (key species) in >29,000 diverse grassland communities in the European Alps, and compared their effects with those of community-level measures of functional composition (weighted means, variances, skewness, and kurtosis). After accounting for the environment, the five most important key species jointly explained more deviance of productivity than any measure of functional composition alone. Key species were generally tall with high specific leaf areas. By dividing the observations according to distinct habitats, the explanatory power of key species and functional composition increased and key-species plant types and functional composition-productivity relationships varied systematically, presumably because of changing interactions and trade-offs between traits. Our results advocate for a careful consideration of species' individual effects on ecosystem functioning in complement to community-level measures.