مجله بوم شناسی کاربردی
پیاپی 18 (زمستان 1395)

In order to evaluate life cycle assessment (LCA) for rice agroecosystems based on mean of nitrogen fertilizer levels (less than 190, 190-200, 200-210, 210-220 and more than 220 kg N ha) during 1999-2012, an experiment was conducted. Four steps includung goal definition and scoping, inventory analysis, life cycle impact assessment and integration and interpretation were computed. Functional unit was considered as one tone paddy. Impact categories were acidification, eutrophication in aquatic and tresstrial ecosystems and global warming. The results showed that the highest paddy yield was obtained 5.35 t.ha-1 in 190-200 kg N ha. The maximum aquatic eutrophication potential was computed for more than 220 kg N ha-1 with 0.79 PO4 equiv./t paddy. EcoX per one tone paddy and maximum environmental impacts was belonged to aquatic eutrophication (0.13 Eco-index per one tone paddy). It seems that system management including green manure, nitrogen fixing species and reduced tillage could be regarded to reduce problematic environmental impacts in rice production systems.

The current study used habitat suitability index to evaluate habitat suitability of Servak forested area located near Yasouj for the Persian squirrel. Habitat variables including elevation, slope, aspect, density of vegetation cover, height of tree, tree diameter, canopy area of tree, distance to roads, distance to villages, and distance to rivers were used in this evaluation. Results showed that five variables including slope, tree diameter, density of plant cover, distance to road and height of tree were the main effective factors in habitat selection of Persian squirrels. Amongst the three stations, Golzar station with the highest habitat suitability index (0.92) has provided the most suitable area for the Persian squirrel. Overall, due to the habitat suitability of the Servak forested area for the Persian squirrel and the substantial number of animals in this region, it is recommended to protect this area by Department of Environment.

To study the effect of climatic factors on Taverniera glabra species distribution in Iran rangelands, climatic variables were selected and factors affecting species distribution were evaluated using factor analysis. Then a spatial distribution map was prepared for all these factors throughout Iran. Factor analysis showed that 9 factors included: temperature, relative humidity, winter precipitation and summer precipitation, partly cloudy days, average wind speed, thunder and snowy days with eigenvalues greater than 1, explained 29.71, 22.32, 9.58, 7.52, 6.80, 6.22, 4.25, 3.69, 2.22 percent of variance, respectively and 92.35% of total variance. Finally, the climatic factors of temperature, relative humidity, average wind speed and thunderstorm were identified as the most important factors affecting distribution of vegetation types which Taverniera glabra are dominant species. Furthermore temperature, summer precipitation, average wind speed and thunderstorm factors affecting on distribution of vegetation types in which Taverniera glabra are accompanied species. The results showed that these climatic factors caused distribution of Taverniera glabra in the South East of Iran.

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 Zagros Forests, Kermanshah (Gahvareh).This study was conducted at 70 hectares of Gahvareh forests. In this area, 67 sample plots (400 m2) were used in a 100 × 100 m sampling grid. In each plot, total number and species of trees and all seedlings which had diameter less than 7.5 cm were recorded. We also recorded asexual regeneration in ¼ plots (100 m2).Then the spatial continuity was described using geostatistics (variogram and cross- variogram). The variograms of variables revealed the presence of spatial autocorrelation except evenness index (Sheldon) of trees and sexual regeneration. They had spatial dependence at large ranges that showed the large distance of dependency and homogeny of condition. In addition, cross-variograms indicated a strong spatial relationship between diversity of sexual regeneration and tree diversity and between diversity and richness of asexual regeneration and tree abundance.

Status determination of wildlife habitats is very important in conservation programs and management of wildlife. So, in this study Ursus arctos habitat suitability was modeled using maximum entropy algorithm (MaxEnt) in Shimbar protected area. In order to model the habitat suitability, after investigating and resolving the spatial autocorrelation of occurrence records, spatially independent localities were divided into the calibration and evaluation sets and then were combined with 10 environmental variables (VIF

Having the richest plants biodiversity, Hyrcanian natural mixed-beech forests contribute to the huge carbon pool in the different soil layers. This research aims to develop modeling soil carbon sequestration in terms of the plant biodiversity indices to manage soil carbon stock with respect to trend of sustainability, fertility, carbon cycle, and planning to face with climate change in local/ regional scales. After measuring plants biodiversity indices and soil carbon factor over the field operations, simple and multiple linear regressions as well as curve estimation regression were applied in the process of modeling. According to Adj.R2, SEE and AIC, simple and multiple linear regressions had no considerable accuracy (AICmin = 힝.74). Analysis of non-linear models showed that model S including index of species dominance belonging to herbal coverage was the best predictor with the least error and highest certainty (AICmin= -171.23) to estimate soil carbon pool in the studied forests. In the following, the results showed that although the log-transformed models with increasing the parameters and adding the correlated explanatory variables were valid (VIF

Rotten and dead trees are the main component of forest ecosystems and play an important role in maintaining forest biodiversity. In this research frequency and characteristics of large diameter trees (normal, rotten, and dead trees) with diameter at breast height greater than 60 cm were studied in two compartments (selective logged and protected) in Asalem-Nav forest. Random systematic sampling method with grid of 100 × 100 m and plot area of 0.2 ha was used for data collection. The results showed frequency and volume of large diameter trees of all three groups in the logged parcel were lower than protected parcel (P