Previous exclosure studies measuring the top-down control of arthropod abundance and herbivory combined the effects of birds and bats. We experimentally partitioned bird predation from bat predation in a lowland tropical forest in Panama and measured the direct effects (arthropod abundance) and indirect effects (herbivory). The exclusion of birds and bats each directly increased arthropod abund...

the rangelands, as one of the largest dynamic biomes in the world,have very capabilities. regulation of greenhouse gases in the earth's atmosphere,particularly carbon dioxide as the main greenhouse gases, is one of these cases.the attention to rangeland, as cheep and reachable resources to sequestrate thecarbon dioxide, increases after the industrial revolution. rangelands comprise thelarge par...

Soil salinity is one of the important factors which can influence the growth anddistribution of plant species. Saline and alkaline rangelands of Golestan Province, Iran withlow-deep underground water level are considered as a halophyte plant species growing area.Attempts have been made to determine soil salinity and its relationship with Frankenia hirsutaL. In order to determine the Electrical ...

Patterns of seed predation, germination, and seedling herbivory were investigated in Panamanian forests. We hypothesized that seed and seedling survival would vary with differences in mammal community composition. We tested this hypothesis at five sites in mainland forests adjacent to Gatun Lake, full terrestrial mammalian granivore/ herbivore communities with top predators; at five sites on Ba...

since renaissance, the natural ecosystems have fallen into a complete state ofdisarray due to the rise in the amount of carbon dioxide. soil, the unsparing stuff, is one of themajor sources of carbon storage, and plays a paramount role in the global equilibrium ofcarbon as well as carbon sequestration. given that iran is benefiting from vast steppes, therate of carbon sequestration in them dese...

Natural regeneration is one mechanism by which native rnixedspecies forests become reestablished on abandoned pasture. This study was done to determine patterns of and requirement for natural regeneration of native species in an open woodland after removal of cattle. Ten 50by 50-m quadrats were randomly selected within a 16-ha exclosure located at 1,700-m elevation inside the Hakalau Forest Nat...

Field surveys of soybean aphid, Aphis glycines Matsumura, and its natural enemies, as well as natural enemy exclosure experiments, were conducted during 2003 and 2004 in soybean fields near Langfang, China. In 2003, aphid density increased six-fold during 12 d in July from 66+/-12 per 10 plants to a seasonal peak of 401+/-79 per 10 plants. Aphid density remained high for another 10 d and declin...