Journal of Range and Watershed Managment

Abstract Abstract
This study aimed to investigate the effect of different intensities of grazing on soil chemical properties on Gonbad paired basins-Hamadan. The objective of this research was to characterize the impact of sheep grazing intensity on soil chemical behavior on mountainous in Hamadan rangelands (Gonbad paired basins). Grazing intensity was classified as light, moderate and heavy, then the soil samples from the three depths of 0-10, 10-20 and 20-30 cm were collected. The soil data was analyzed via SPSS (ANOVA). Results showed that the soil OC, total N content and organic matter decreased significantly with grazing intensity and they were greatest at the surface and decreased with depth. The amount of Calcium and Magnesium won't be affected by grazing intensity. The decreases in soil OC suggest Carbon storage in the soil of grassland declined as grazing intensity increased. Combined with the decreases in soil TN content, this also means heavy grazing could lead to decreases in soil quality and fertility. Uneven grazing intensity is an inherent feature of a season long-grazing system and there are risks to avoid quality and environmental health.

Abstract For the scientific and accurate management of rangeland ecosystems, having information about ecosystem as indicators of ecosystem health and function is needed. The aim of this research is to study the effects of grazing on soil surface indicators and rangeland functional properties by using Landscape Functional Analysis (LFA) method. For this purpose, the present study was conducted in two regions, including the enclosure and outside the enclosure, Donna rangelands of Siah Bisheh watershed. Systematic sampling was carried out by three 100 m transects with 100 m interval.  Along each transect, ten 1m² plots with 10 m interval were placed. In order to compare triple indices including infiltration, stability and nutrient cycling in two regions of the enclosure and outside the enclosure, the independent T test was employed in this study. The results showed that there are significant differences among soil surface indicators except soil surface cover, perennial plants, trees and shrubs canopy, surface roughness and erosion type and severity (P < 0.05). Therefore, there are significant differences among three functional attributes of rangeland in these study regions.

Abstract Determination of rangeland species palatability has some functions such as defining the rangeland grazing capacity and plant composition estimation. Despite the importance of palatability in rangeland management, no appropriate palatability indicator has been defined yet. Therefore, developing an accurate, applicable, general, and simple indicator for plant palatability estimation seems crucial. This research is an effort in this regard. To investigate the relationship between plant secondary compounds and palatability, plant species composition in the study area and in the sheep and goat diet as well as selection index were measured using chronometric and filming method. In the next stage, main plants’ secondary compounds in livestock diet were determined using GC/MSS. Then plants’ secondary compounds were ordinated using principle component analysis (PCA) method. Quantitative value of each plant species Eigen values on each of the main axis of PCA was regarded as a criterion for differentiation of plant species based on its secondary compounds. Finally, correlation between selection index of each plant species by sheep and goat (as dependent variable) with each plant species Eigen values on PCA axis (as independent variable) was determined. The results showed that there is a significant negative relationship between the selection index of the species by sheep and goat with its secondary compounds (P≤0.05). So, it is concluded that secondary compounds are effective factors in animal’s diet selection for grazing. Therefore, secondary compounds are recommended as an important factor for plant palatability determination.

Abstract Global warming and climate change have drawn special attention to soil and its potential for stable carbon sequestration. Soils are the largest stores of carbon in terrestrial carbon cycle and contain about three times more carbon than vegetation cover and two times more than that of atmosphere. Studying the effects of grazing on soil carbon storage is important because of the major role soil organic carbon has in production. Grazing is potent for changing the carbon storage of rangeland ecosystems. In this research, the effect of different grazing intensities on carbon sequestration and nitrogen stabilization in pastures cultivated with Atriplex canescens in Shahriar was studied. Soil and plant samplings were done in low, moderate and high grazing intensity areas as well as exclosure, using randomized – systematic method. Soil samples were taken from 0-10, 10-30 and 30-100 Cm depths of 20 soil profiles. In each soil sample, stone percent, bulk density, organic carbon and nitrogen were calculated. Data analysis was done using one – way ANOVA and Duncan test in SPSS 17 software. Results showed that all three grazing intensities have caused significant reduction in carbon and nitrogen of soil.

Abstract Grazing animals affect rangeland vegetation structure and function both directly and indirectly.
These effects can be assessed in exclosures. In this study, vegetation changes inside and outside of
exclosures of Tanglaybid rangelands, located in south-western part of Yazd province, have been
investigated. Vegetation changes study was carried out in 3 key areas inside and also 3 key areas
outside of exclosure and lasted for 5 years (2000-2005). Every key area included 3 transects of 100
meters long and 40 meters intervals. The transects were selected vertical to slope, including 10
fixed plots (2×1 m2). Vegetation cover, density and frequency percentage of each plot species were
measured annually. The random- systematic method was applied as a sampling method. Vegetation
changes inside and outside of exclosure were assessed, in a completely random plan, applying
Duncan's test (P < 0.05). The results showed that vegetation cover percentages increased
significantly (P < 0.05), inside the exclosure comparing to outside of it. Mean coverage of annual
and perennial grasses and also bushes, inside the exclosure comparing to its outside increased 47,
38 and 7%, respectively. Thus, in present research, exclosure has positive effects on vegetation
cover changes of several species. Frequency percentage results showed that there was no significant
difference, inside against outside the exclosure in 2000, 2001, 2002, 2003, and 2004. Regarding
density, there was significant difference only in 2001.The results can be considered in future
management of the area's rangelands and similar regions throughout Iran

Abstract Considering the importance of vegetation changes and awareness of its destruction or improvement trends in programming and its proper managing of utilization, this study was conducted in order to survey the effects of grazing on the qualitative and quantitative components of vegetation (including life form, growth form, palatability class, plant families and species diversity) and recognition their most important changes in both grazing and enclosed sites in Kalpush plain, Golestan provience. For this purpose, samples were taken via 78 plot 1 square meter in a randomly- systematic method. Mean comparison of the components and recognition of the most changeable components in consequent implementing grazing management were done with t-student test and principle component analysis (PCA) respectively using Spss software. According to the vegetation study, 13 species belong to Asteraceae family and 10 species to Poaceae family and there are 69 Herbaceous species, 13 Grass species and 5 shrubs species of plants in this region. The results of t-Student test indicate an increase in relative density of Therophytes and class I plants, and decrease in Cryptophytes and class III in the enclosed. Also the results point out that grazing has caused increasing in the relative canopy of Shrubs and Champhyte and decreasing in Therophytes, Forbs in the region. Comparison of relative density and canopy cover of plant species in two sites showed a relatively good effect of rangeland enclosing in increasing of the density, restoration and recovery of species composition and diversity. Principal component analysis also showed that the most changeable components in consequent of rangeland enclosing were Forbs, Hemicryphtophyte, Therophyte, Appiacea and Brassicacea families in positive and Shrubs in negative of first axis. Also the Papaveracea and Asteracea families have the most incremental changes in the second component.

Abstract This study investigates monthly and seasonal variations of carbon emission from the soil at different grazing intensities. Three areas of exclosure, low and high grazing intensities were selected in Ghoosheh region of Semnan province. Carbon emission was measured monthly, in each treatment applying alkali traps (CSC) during a year. Emission and grazing data were analyzed, using a factorial experiment in a completely randomized design with four replications. To investigate the relation of soil moisture and air temperature with carbon emissions in each area, Pearson correlation was used. Results showed that the emission levels under different grazing intensities had significant difference. The highest emission occurred in high grazing intensity, in August (3.34 g C m-2 day-1) and lowest in February (0.033 g C m-2 day-1) in exclosure. The seasonal distribution of emission showed the highest amount, in summer, autumn, winter and spring respectively. There was also a negative correlation between carbon emissions and soil moisture.