Nutrient concentrations and their ratios are important factors influencing the primary productivity of a reservoir. Based on the study results of Bosga and Khaji Kotnoor reservoirs it was noticed that, in addition to their nutrient status and ratios and other chemical variables, physiographical factors such as geography, catchment land use, water basin morphology, bathymetry and changing water levels or flushing rates also influenced the productivity of these two reservoirs.

Litter decomposition of tree species like Alnus nepalensis, Lyonia ovalifolia, Myrica esculenta, Pyrus pashia and Rhododendron arboreum was studied in a Parkandi village landscape, Garhwal Himalaya. Initial nutrient concentration of litter was estimated. Carbon content varied from 44.45-48.34%, lignin from 15.3-28.23%, cellulose from 31.4-46%, N from 0.69-2.93%, P from 0.021-0.072%, K from 0.73-2.93% across species. Carbon concentration seemed the most stable/least variable chemical attribute. N fixing A. nepalensis had the highest concentration of N but not of P while R. arboreum had the highest concentration of K. Annual decomposition constant varied from about 1 in A. nepalensis and P. pashia, 0.5 in case of M. esculenta and R. arboreum. Though A. nepalensis had higher concentration of N and lower concentration of lignin compared to P. pashia, the two species had almost similar half-life (0.7 years) suggesting the importance of attributes other than chemical characteristics in determination of decomposition rate.

A phenomenon that has in several recent years become a permanent feature with the country's provinces is The Dust Phenomena. The phenomenon occurred in the short time of the1994 in some Southwestern cities of Iran and gradually its severity increased. Various causes such as human interventions in the irrational use of surface and groundwater resources, destruction of vegetation, weakening of Soil due to Agriculture, and frequent use of land and intensification of natural factors such as drought and climate changes have been expressed as a basis for the occurrence of this phenomenon. So these storms are a sign of poor management and bad policy due to the use of traditional technologies regardless of rapid population growth. Because the particles move; effects of this phenomenon is not limited to of region of occurrence but also has an impact on many other terrestrial and aquatic ecosystems of the world. The purpose of this paper is to express a summary of the findings about the dust storms, its effects, and effective factors and ways to confront it worldwide. With the hope that by more cooperation from governments and active investigators in operational studies a day comes that we never witness the occurrence of this phenomenon in our country.