Mohadeseh Arab sarbizhan; Mahdiyeh Ebrahimi; Majid Ajoulou
Volume 23, Issue 2 , September 2016, , Pages 382-373
Abstract
This research was aimed to investigate the effects of restoration practices on rangeland health in Jiroft. The study was conducted using landscape function analysis (LFA). Three study sites including exclosure (Jebalbarz), contour furrow, and crescent pond in rangelands under grazing management (Anbarabad) ...
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This research was aimed to investigate the effects of restoration practices on rangeland health in Jiroft. The study was conducted using landscape function analysis (LFA). Three study sites including exclosure (Jebalbarz), contour furrow, and crescent pond in rangelands under grazing management (Anbarabad) were selected. Sampling was performed in a random-systematic manner using transects of 50 m and 100 m length, and patches and inter-patches were identified on each transect. Then, the length and width of the patches and distance between them were measured. Five replicates of each patches and inter-patches were selected and 11 soil factors were assessed. In the three study sites and control groups, functional indexes including infiltration, stability, and nutrient cycling were calculated through sum of scores using LFA software and changed to percent values. According to the results, the management activities applied could change the rangeland functional indicators and characteristics, so that range condition improved by exclosure. In addition, the average values recorded for the rangeland health indicators in ecological patches of restoration practices were higher as compared with control group. Duncan test results showed that there were significant differences for three functional indicators among all treatments, so that restoration practices could improve the rangeland function.
Azam Khosravi Mashizi; Gholamali Heshmati; Adel Sepehri; Hossein Azarnivand
Volume 18, Issue 2 , September 2011, , Pages 244-257
Abstract
Aim of this study was to introduce of the functional threshold by ecological process changes along grazing gradient to determine destroyed area.In order to prove the existence of a threshold, two linear models and three nonlinear models (exponential curve, a piecewise regression and a sigmoid logistic) ...
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Aim of this study was to introduce of the functional threshold by ecological process changes along grazing gradient to determine destroyed area.In order to prove the existence of a threshold, two linear models and three nonlinear models (exponential curve, a piecewise regression and a sigmoid logistic) were fitted on stability, infiltration and nutrient cycling data.Two nonlinear models (exponential curve and a piecewise regression) provided a much better fit to the data than the linear models. It is the evidence of threshold along grazing gradient.Results also showed that ecosystem function descended near the water point that it needs special attention of the managers.The passing of the structural threshold, increase of invasive vegetation and animal trampling were identified as the main factors in the decline of ecosystem function near the water point and occurrence of functional threshold.According to the results, the recognition of the threshold is suggested for rangeland ecosystem because defining the threshold will help land managers to prevent the occurrence of undesirable states and promote for sustainable management of rangeland ecosystems.
Syed Ata Rezaei; Hosein Arzani
Volume 14, Issue 2 , January 2007, , Pages 232-248
Abstract
In this research, to identify the functioning of the soil-landscape system and its effects on plant growth for native rangeland, we investigated the relationships between soil properties and Landscape Function Analysis (LFA) indices and between plant growth characteristics and LFA indices. The results ...
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In this research, to identify the functioning of the soil-landscape system and its effects on plant growth for native rangeland, we investigated the relationships between soil properties and Landscape Function Analysis (LFA) indices and between plant growth characteristics and LFA indices. The results interpreted based on statistical analysis and expert knowledge. This research was carried out for a semi-arid rangeland in the Lar aquifer in Iran. Land stratification allowed the study area to be subdivided into Land Units, according to specified criteria including landform attributes (slope, aspect, and altitude), and vegetation type. A factorial model on the basis of a completely randomized design was used to analyze the data collected from 236 land units. The landscape function indices including nutrient cycling index, Infiltration index, Stability index, and Landscape organization index were derived by various integrations of soil surface attributes. Landscape attributes differed from one another in their effects on the different landscape function indices. Increasing slope gradient significantly reduced all landscape function indices as well as soil organic carbon and total nitrogen percentages. Slope class exhibited highly significant interaction effects with vegetation type factors for stability, nutrient cycling, and landscape organization indices. Aspect did not significantly affect stability, infiltration, and landscape organization indices, but significantly affected the nutrient cycling index. The Duncan test indicated that north aspect (shady side) had the highest mean value (28.42) and south aspect the lowest mean value (25.57) for nutrient cycling index. These results are consistent with the effects of aspect on total soil nitrogen and soil organic carbon percentage for which the north aspect had the highest values. The values declined in the sequence east, west, and south aspects respectively. This research indicates that the nature of native rangeland plant communities and their measures of production are closely related to nutrient cycling index.