Document Type : Research Paper
Authors
1
M. Sc. student of Forest Management, Faculty of Natural Resources, Tarbiat Modares University. Noor, I. R. Iran
2
Assistant Professor, Range Management, Faculty of Natural Resources, Tarbiat Modares University. Noor, I. R. Iran
3
Professer, Forest Management, Faculty of Natural Resources, Tarbiat Modares University. Noor, I. R. Iran
Abstract
Considering the degradation of large areas of lowland forests and decreasing tree density, it is assumed that nutrient cycle controlling factors and habitat dynamics also show significant changes. Accordingly, the present study aimed to study the effects of different intensities of forest degradation and tree density on the dynamics of soil microbial activities and biochemical processes. Following field inspection, three forest areas with degradation intensities of high (deforested area; including 8 trees per hectare), moderate (disturbed forest; including 185 trees per hectare) and low (protected forest; including 321 trees per hectare) with hornbeam and iron trees as dominant species, in the plain region of Noshahr city were considered. A total of 15 soil samples from each area were transferred to the laboratory and physico-chemical characters, microbial activities (i.e. basal and induced respiration, microbial biomass of carbon, nitrogen, and phosphorous) and nitrogen mineralization dynamic (i.e. net rates of ammonification, nitrification and nitrogen mineralization) were measured. The results indicate that the protected forest has higher microbial activity, net ammonification (both summer and fall), and nitrification (in summer) rates, which are related to higher clay, humidity, and also fertility under these land cover. Whereas, disturbed forest and the deforested area generally have lower microbial activity and mineralization processes. The results of the present study indicate that forest degradation has negative effects on many microbial indices and biochemical activities related to soil nutrient cycles.
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