نتایج جستجو برای: tree species richness and abundance of herbaceous
تعداد نتایج: 24089229 فیلتر نتایج به سال:
spiders are one of the most abundant invertebrates in terrestrial ecosystems that have a good potential to pest control in crops. species richness and abundance of spiders and the effects of different agricultural practices on these predators were studied in winter wheat fields in shirvan, mashhad and gonabad, cities in northeast of iran. in each region, high and low input fields of winter whea...
Livestock grazing practices in rangelands are being recognized as management tool for environmental protection and increased livestock productivity. Continuous grazing has been largely reported to reduce pasture productivity and increase environmental degradation. Rotational grazing is an alternative to continuous grazing and is considered to reduce negative environmental effects and provide qu...
The regeneration is one of the most important phenomena in forest ecosystems and the most important factor of development and sustainability of forests. Assessment of the regeneration is one of the best criteria for monitoring forest function stability. The aim of this study was to investigate the spatial variability of regeneration diversity and its relationship with tree species diversity in ...
We evaluated variability in cover estimation data obtained by (1) two sampling teams who double sampled plots and (2) one team that used two methods (line intercepts and visual estimation of cover classes) to characterize vegetation of herbaceous wetlands. Species richness and cover estimates were similar among teams and among methods, but one sampling team scored cover higher than the other. T...
Predatory arthropods can exert strong top-down control on ecosystem functions. However, despite extensive theory and experimental manipulations of predator diversity, our knowledge about relationships between plant and predator diversity--and thus information on the relevance of experimental findings--for species-rich, natural ecosystems is limited. We studied activity abundance and species ric...
in order to evaluate the effects of forest road on regeneration and vegetation composition in district no. 2 shafaroud, a road was selected with the length of 400 m that the altitude, aspect, slope variations and species composition were similar. five transects in right and 5 transects in left side of road, were established as perpendicular. in each transect 5, 15, 25 and 35 m distances were de...
increasing patch edges in natural habitats, as a result of habitat fragmentation, are a major threat for wildlife populations, especially avifaunal communities. habitat edges provide different conditions compared to the core area which can directly or indirectly cause changes in species number, population and composition. this fact will demand a dissimilar management strategy. this study was co...
A biodiversity investigation was carried out in the wild pistachio research forest located in southwest of Fars Province between 52˚ 30́́ to 52˚ 40́́ longitude and 29˚ to 29˚ 15́ latitude in an areaof 9374 Ha area. 72 sampling transects fifty meters long were designated using systematic-random design. In each sampling plot a list of bush, shrub, and tree species and their abundance were recorded. Th...
126 abstract: in this research we studied the effects of cyclic hydration and dehydration of cysts of artemia urmiana and artemia parthenogenetica on the hatching percentage, survival and growth. the experiment was carried out in 3 treatments (1-3 hydration/dehydration cycles) with 3 replicates for each treatment. later effects of cold preservation at -20°c during three time periods were ...
in this study, a simple, rapid and selective method was developed for the determination of dexamethasone. the proposed method is based on inhibitory effect of dexamethasone on the oxidation of orange-g by bromate in sulfuric acid media. the reaction was followed spectrophotometrically at 478.5 nm (?max). under optimum experimental conditions, (72.6 ?mol l-1 of orange-g, 0.76 mol l-1 of h2so4, 0...
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