Biodiversity is declining worldwide from reductions in both species richness and evenness. Field experiments have shown that primary productivity is often reduced when richness of plant species is lowered. However, experiments testing richness effects have used evenness levels that are much higher than normally encountered in plant communities and have been based on the assumption that species ...

Descriptions of 247 forest stands at Waipoua Forest, Northland, were used to explore relationships between species richness (alpha-diversity) of the vascular flora and stand environmental characteristics, both in terms of total flora and within a number of the component synusiae. The Waipoua forests, with an average of 52 species per forest stand, are comparatively species-rich compared to othe...

Studies of biodiversity typically assume that all species are equivalent. However, some species in a community maintain viable populations in the study area, while others occur only occasionally as transient individuals. Here we show that North American bird communities can reliably be divided into core and transient species groups and that the richness of each group is driven by different proc...

One of the most investigated patterns in species diversity is so-called latitudinal gradient, that is, a decrease richness from equator to poles. However, few studies this pattern insects at global scale because insufficient taxonomic and biogeographical information. Using estimates earwig country level, their gradient was modelled globally for two hemispheres separately after correcting differ...

Global warming, eutrophication, fisheries overexploitation, species invasions, and habitat loss are the major threats to freshwater biodiversity. The aim of this study was determine richness diversity fish in 535 Polish lakes different morphometry (area more than 50 ha a maximum depth ranging from 0.4 108.5 m) trophic status (from oligotrophy hypereutrophy). A total 39 were found studied lakes,...

Pollinating insect populations, essential for maintaining wild plant diversity and agricultural productivity, rely on (semi)natural habitats. An increasing human population is encroaching upon and deteriorating pollinator habitats. Thus the population persistence of pollinating insects and their associated ecosystem services may depend upon on man-made novel habitats; however, their importance ...

We present empirical evidence that the direct and indirect effects of species richness on ecological processes depend on a system’s disturbance regime. We manipulated the number of species of freshwater suspension feeders (net-spinning caddisflies) in laboratory stream mesocosms where communities were either subject to a periodic mortality or were left undisturbed. We hypothesized that disturba...

In the present study, some ecological factors were studied for Amphipoda at different depths. The Shannon, Margalef, and Hill indices were used to determine the  species diversity, richness and evenness, respectively. In addition, the association and niche overlap values were estimated. Indices of species richness and diversity were highest at 50 and 100m depths, respectively.  The or...