hyrcanian forests in northern slope of alborz support high bird richness and abundance same as central of europe. in this study, efficiency of different methods including fixed-width transect, variable-width transect, fixed-radius point count and variable circular plot samplings were compared in order to present the most reliable methods for surveying and monitoring of diurnal forest birds in f...

In this paper the authors describe the limnological approaches, the sampling methodology, and strategy adopted in the study of the Xingu River in the area of influence of future Belo Monte Power Plant. The river ecosystems are characterized by unidirectional current, highly variable in time depending on the climatic situation the drainage pattern an hydrological cycle. Continuous vertical mixin...

nowadays, temperature increase, rainfall decrease and its effect on the time dynamics of carbon fixation cycle still are faced by many uncertainties. net primary production (npp) is one of the main factors of carbon cycle; precipitation and temperature measurement are known as two useful tools to study different ecosystems stability and resilience in terms of climate. hence, in this study, npp ...

Agriculture and urban activities are major sources of phosphorus and nitrogen to aquatic ecosystems. Atmospheric deposition further contributes as a source of N. These nonpoint inputs of nutrients are difficult to measure and regulate because they derive from activities dispersed over wide areas of land and are variable in time due to effects of weather. In aquatic ecosystems, these nutrients c...

pastures play an important role in protecting environment and ecosystems. unfortunately more than 40 percent of pasturess in the world have been destroyed and 20 percent of destroyed pastures are located in developing countries. application of solar energy could significantly contribute to preserving the pastures. the main purpose of this study was to examine the role of solar energy in protect...

Ecologists have greatly advanced our understanding of the processes that regulate trophic structure and dynamics in ecosystems. However, the causes of systematic variation among ecosystems remain controversial and poorly elucidated. Contrasts between aquatic and terrestrial ecosystems in particular have inspired much speculation, but only recent empirical quantification. Here, we review evidenc...

Under predicted global climate change, species will be gradually exposed to warmer temperatures, and to a more variable climate including more intense and more frequent heatwaves. Increased climatic variability is expected to have different effects on species and ecosystems than gradual warming. A key challenge to predict the impact of climate change is to understand how temperature changes wil...