Explore the vast range of titles available.

We studied factors shaping the diversity and abundance of small mammals in temperate woodlands in northeastern Poland at local (within the forests) and regional (among the forests) scales. We compared diversity and abundance of rodents and insectivores in habitats covering the widest possible range of forest productivity in Central Europe, from dry coniferous to wet deciduous forests. Small mammals were live-trapped during summer (2004–2006) on 206 circular plots. On the regional scale, the number of small mammal (rodent and shrew) species positively correlated with the proportion of deciduous stands in the woodland's area. In all forests, the bank vole (Myodes glareolus) and the yellow-necked mouse (Apodemus flavicollis) dominated, and their joint proportion in the community increased with share of deciduous forest habitats. On the local scale, the number of species increased significantly with productivity of both capture site and the whole woodland. Variation in rodent abundance was influenced mainly by forest productivity at the capture site, productivity of the whole woodland, and month of capture. Only a minor part of the variation in shrew abundance was explained by habitat productivity. The relationship between forest productivity and small mammal diversity was linear and positive on both local and regional scales. The different responses of rodents and insectivores to increasing productivity could be due to a wider ecological niche of shrews and their competition for space with rodents. Nomenclature: Mitchell-Jones et al., 1999; White, White & Walters, 2005; Wilson & Reeder, 2005; Seneta & Dolatowski, 2006.

Functional diversity (FD) has become a principal concept for revealing mechanisms driving community assembly and ecosystem function. Multiple assembly processes, including abiotic filtering, competition and multi‐trophic relationships, operate simultaneously to structure FD. In water‐limited plant communities, FD is likely to reflect trade‐offs between drought resistance vs. disturbance resistance and competitive ability. We propose a mathematical mechanistic model for understanding the organization and function of water‐limited plant communities. The approach captures the interplay between abiotic filtering, below‐ and above‐ground competition and disturbance. We exploit this powerful model to uncover mechanisms underlying changes in functional diversity along stress gradients. Our approach links biomass production and FD to environmental conditions through plant resource capture ability. Functional groups are defined along a single trade‐off axis according to investment in capturing light (shoot) vs. water (root). Species growth rate is determined dynamically by the species traits, water availability and grazing stress. We derive biomass production, functional diversity and composition along precipitation and grazing gradients. Model's results revealed several regimes structuring FD along the precipitation gradient: ‘Struggle for water’ at low precipitation, ‘competition for water’ at intermediate precipitation and ‘competition for light’ at high precipitation. We observed a shift in grazing effect on FD from negative at very low precipitation, to positive at higher precipitation. Unimodal FD–grazing intensity relationship was observed under high precipitation, while under low precipitation, FD decreased moderately with increasing grazing intensity. Synthesis. Our model showcases how fundamental tradeoffs in plant traits may drive functional diversity and ecosystem function along environmental gradients. It offers a mechanism through which novel understandings can be obtained regarding the interplay between water stress, below‐ and above‐ground competition and disturbance intensity and history. We discuss further model testing possibilities as well as required empirical work.

Land set aside for preservation of biodiversity often has low productivity. As biodiversity generally increases with productivity, due to higher or more diverse availability of resources, this implies that some of the biodiversity may be left unprotected. Due to a lack of knowledge on the species diversity and conservation value of low‐productivity habitats, the consequences of the biased allocation of low‐productivity land for set‐asides are unknown. We examined the conservation value of boreal low‐productivity forests (potential tree growth <1 m3 ha−1 year−1) by comparing assemblages of tree‐ and deadwood‐dwelling lichens and forest stand structure between productive and low‐productivity forest stands. We surveyed 84 Scots pine‐dominated stands in three regions in Sweden, each including four stand types: two productive (managed and unmanaged) and two low‐productivity stands (on mires and on thin, rocky soils). Lichen species richness was the highest in low‐productivity stands on thin soil, which had similar amounts and diversity of resources (living trees and dead wood) to productive unmanaged stands. Stands in low‐productivity mires, which had low abundance of living trees and dead wood, hosted the lowest lichen richness. Lichen species composition differed among stand types, but none of them hosted unique species. The differences in both species richness and composition were more pronounced in northern than in southern Sweden, likely due to shorter history of intensive forestry. Synthesis and applications. Boreal low‐productivity forests can have as high conservation value as productive forests, which should be reflected in conservation strategies. However, their value is far from uniform, and conservation planning should acknowledge this variation and not treat all low‐productivity forests as a uniform group. Some types of low‐productivity forest (e.g. on rocky soil) are more valuable than others (e.g. on mires), and should thus be prioritized in conservation. It is also important to consider the landscape context: low‐productivity forests may have higher value in landscapes where high‐productivity forests are highly influenced by forestry. Finally, although low‐productivity forests can be valuable for some taxa, productive forests may still be important for other taxa. We studied the conservation value of low‐productivity boreal forests by surveying tree‐ and deadwood‐dwelling lichens in four types of stands: two productive (managed and unmanaged) and two low‐productivity stands (on mires and on thin, rocky soils). The stands were located in three different regions in Sweden. Low‐productivity stands on thin soil hosted the highest lichen species richness, whereas those on mires hosted the lowest. The differences in species richness were more pronounced in northern than in southern Sweden, likely due to shorter history of intensive forestry. We conclude that boreal low‐productivity forests can have as high conservation value as productive; however, their value is not uniform but may depend on the type of the low‐productivity forest as well as on the surrounding landscape.

Nutrient supply to ecosystems has major effects on ecological diversity, but it is unclear to what degree the shape of this relationship is general versus dependent on the specific environment or community. Although the diet composition in terms of the source or proportions of different nutrient types is known to affect gut microbiota composition, the relationship between the quantity of nutrients supplied and the abundance and diversity of the intestinal microbial community remains to be elucidated. Here, we address this relationship using replicate populations of Drosophila melanogaster maintained over multiple generations on three diets differing in the concentration of yeast (the only source of most nutrients). While a 6.5‐fold increase in yeast concentration led to a 100‐fold increase in the total abundance of gut microbes, it caused a major decrease in their alpha diversity (by 45–60% depending on the diversity measure). This was accompanied by only minor shifts in the taxonomic affiliation of the most common operational taxonomic units (OTUs). Thus, nutrient concentration in host diet mediates a strong negative relationship between the nutrient abundance and microbial diversity in the Drosophila gut ecosystem. Using experimental Drosophila melanogaster populations, we studied the effect of quantity of nutrients in host's diet on gut microbiota community. While an increase in nutrient (yeast) concentration in the diet led to greater microbiota abundance, it also resulted in a sharp decline in their alpha diversity. This resembles the productivity–diversity relationship often found in grassland plant communities but not reported previously for gut microbiota.

1. Understanding the productivity-diversity relationship (PDR) is a key issue in biodiversity-ecosystem functioning research, and has important implications for ecosystem management. Most studies have supported the predominance of a hump-shaped form of PDR in which species richness peaks at an intermediate level of productivity. However, this view has been challenged recently on several grounds. 2. Based on data from 854 field sites across the Inner Mongolia region of the Eurasian Steppe, we tested the form of PDR at different organizational levels (association type, vegetation type and biome) and multiple spatial scales (local, landscape and regional). 3. Our results showed that a positive linear, rather than hump-shaped, form was ubiquitous across all organizational levels and spatial scales examined. On the regional scale, this monotonic PDR pattern corresponded closely with the gradient in mean annual precipitation (MAP) and soil nitrogen. Increasing species dissimilarity with productivity could also contribute to the positive linear form of PDR. 4. Our results also indicated that grazing decreased both primary productivity and species richness but, intriguingly, not the form of PDR. 5. Synthesis and applications. This study provides the first direct test of the productivity-diversity relationship for the world's largest contiguous terrestrial biome - the Eurasian Steppe. The predominance of a positive linear relationship in this region defies the commonly held view that a unimodal form of PDR dominates terrestrial ecosystems, supported mainly by studies in Africa, Europe and North America. It suggests that precipitation has a greater control on the productivity-diversity relationship in the Eurasian Steppe than grasslands elsewhere. Also, the positive linear relationship is surprisingly robust to grazing. Our results provide new insight into the productivity-diversity relationship and have several implications for restoring degraded lands and understanding ecological consequences of climate change in the Eurasian Steppe.

Understanding the relationship between species richness and productivity is fundamental to the management and preservation of biodiversity. Yet despite years of study and intense theoretical interest, this relationship remains controversial. Here, we present the results of a literature survey in which we examined the relationship between species richness and productivity in 171 published studies. We extracted the raw data from published tables and graphs and subjected these data to a standardized analysis, using ordinary least-squares (OLS) regression and generalized linear-model (GLIM) regression to test for significant positive, negative, or curvilinear relationships between productivity and species diversity. If the relationship was curvilinear, we tested whether the maximum (or minimum) of the curve occurred within the range of productivity values observed (i.e., was there evidence of a hump?). A meta-analysis conducted on the distribution of standardized quadratic regression coefficients showed that the average quadratic coefficient was negative (i.e., the average species richness-productivity relationship was curvilinear and decelerating), and that the distribution of standardized quadratic regression coefficients was significantly heterogeneous (i.e., the studies did not sample the same underlying species richness-productivity relationship). Looking more closely at the patterns of productivity-diversity relationships, we found that, for vascular plants at geographical scales smaller than continents, hump-shaped relationships occurred most frequently (41-45% of all studies). A positive relationship between productivity and species richness was the next most common pattern, and positive and hump-shaped relationships co-dominated at the continental scale. For animals, positive, negative, and hump-shaped patterns were common at most geographical scales, and no one pattern predominated. For both plants and animals, hump-shaped curves were relatively more common in studies that crossed community boundaries compared to studies conducted within a community type, and plant studies that crossed community types tended to span a greater range of productivity compared to studies within community types. Sample size and plot size did not affect the probability of finding a particular productivity-diversity relationship (e.g., positive, hump-shaped, etc.). However, hump-shaped curves were especially common (65%) in studies of plant diversity that used plant biomass as a measure of productivity, and in studies conducted in aquatic systems.

Aim: To evaluate the strength of evidence for hypotheses explaining the relationship between climate and species richness in forest plots. We focused on the effect of energy availability which has been hypothesized to influence species richness: (1) via the effect of productivity on the total number of individuals (the more individuals hypothesis, MIH); (2) through the effect of temperature on metabolic rate (metabolic theory of biodiversity, MTB); or (3) by imposing climatic limits on species distributions. Location: Global. Methods: We utilized a unique ' Gentry-style' 370 forest plots data set comprising tree counts and individual stem measurements, covering tropical and temperate forests across all six forested continents. We analysed variation in plot species richness and species richness controlled for the number of individuals by using rarefaction. Ordinary least squares (OLS) regression and spatial regressions were used to explore the relative performance of different sets of environmental variables. Results: Species richness patterns do not differ whether we use raw number of species or number of species controlled for number of individuals, indicating that number of individuals is not the proximate driver of species richness. Productivityrelated variables (actual evapotranspiration, net primary productivity, normalized difference vegetation index) perform relatively poorly as correlates of tree species richness. The best predictors of species richness consistently include the minimum temperature and precipitation values together with the annual means of these variables. Main conclusion: Across the world's forests there is no evidence to support the MIH, and a very limited evidence for a prominent role of productivity as a driver of species richness patterns. The role of temperature is much more important, although this effect is more complex than originally assumed by the MTB. Variation in forest plot diversity appears to be mostly affected by variation in the minimum climatic values. This is consistent with the ' climatic tolerance hypothesis' that climatic extremes have acted as a strong constraint on species distribution and diversity.

Aim: We analysed marine phytoplankton diversity data as a function of latitude, temperature, primary production and several environmental and biological variables to ascertain whether large-scale variability in the diversity of marine nano-and microphytoplankton (including diatoms, dinoflagellates and coccolithophores) follows similar patterns to those observed for macroorganisms. For the first time we explored these relationships after correcting the observed patterns of species richness by sampling effort. Location: The global ocean. Methods: To standardize the estimates of species richness by sampling effort we used interpolation and extrapolation based on Hill numbers and shareholder quorum subsampling (SQS) methods. Then, we fitted linear and quadratic models to species richness data to explore their variability with latitude, inverse temperature and biomass. These relationships were compared with the patterns obtained from non-standardized data. In addition, we used a stepwise multiple linear regression model to explain the variability of species richness as the combined effect of multiple drivers acting together. Results: Marine phytoplankton diversity was weakly correlated with latitude, temperature or biomass. The hotspots of species richness at intermediate latitudes largely vanished after standardization for sampling effort. Neither latitude, temperature, primary production (as diagnostics of energy supply) nor any other variable or combination of variables, explained the patterns of phytoplankton species richness. Main conclusions: None of the hypotheses tested explained a significant amount of the variability in species richness. The patterns observed for microorganisms in previous studies may have resulted at least partially from differences in sampling effort along productivity gradients and systematic undersampling of species. We conclude that large-scale processes such as passive dispersal and recurrent habitat recolonization dominate the distribution of species. Sampling protocols and data analyses must be improved in order to obtain estimates of diversity that are comparable across ecosystems.

We evaluated whether the kind of nutrient limitation (N, P, or K) may affect species richness-productivity patterns and subsequently may explain variation in species richness and in richness of threatened species. We present a data set from previous studies in wetlands in Poland, Belgium, and The Netherlands and examine species richness-productivity patterns for vascular plants in all 150 sites together as well as for N-, P-, and K-limited sites separately. The kind of nutrient limitation was assessed by N:P, N:K, and K: P ratios in the vegetation. Critical values for these ratios were derived from a literature review of fertilization experiments. The kind of nutrient limitation influenced species richness-productivity patterns in our 150 sites through large differences in productivity. P (co)-limitation occurred only at low productivity, K (co)-limitation up to intermediate productivity, and N limitation along the entire productivity gradient. There was a decreasing trend in species richness with increasing productivity for K (co)-limited sites, whereas for both the N-limited sites and P (co)-limited sites a sort of \"filled hump-shaped curve\" was observed. The species richness-productivity relationship for threatened species was restricted to a much narrower productivity range than that for all species. Richness of threatened species was higher in P (co)-limited sites than in N-limited sites, suggesting that increased P availabilities in wetlands may be particularly important in causing disappearance of threatened species in western Europe. The role of nutrient limitation in species richness-productivity relationships not only reveals mechanisms that may explain variation in species richness and occurrence of threatened species, but it also may be important for nature management practice.