جستجوی مقالات مرتبط با کلیدواژه "اصلاح مراتع" در نشریات گروه "آبخیزداری، بیابان، محیط زیست، مرتع"

A large area of Iran rangelands is located in arid and semi-arid areas which a significant percentage of them have been degraded and are not in good condition. In these areas, vegetation restoration is not easy due to the water scarcity. Water harvesting operations are among the necessary management measures to restore and develop the rangelands of these areas. Water harvesting operations improve the rangeland restoration conditions by increasing the available moisture for plants. But not all water harvesting operations are equally effective and may not have the same effect on rangeland restoration in different areas. Therefore, it is necessary to compare such operations in different areas to be able to choose the best water harvesting operations. Therefore, this study investigates the efficiency of two water harvesting methods in the rehabilitation of arid vegetation in Hormozgan province.

In this study, three treatments have been considered: control area, area under microcatchment operation and area under water spreading system. Systematic-random sampling method was used to measure vegetation. Three 100 m transects were laid out in each area. Vegetation attributes were measured in ten 2×2 m plots located along each transect. In total 90 plots, the percentage of canopy cover and the number of the plant species were recorded. The biological form of plant species was determined based on the Rankier classification method. In addition, the percentage of rocks and pebbles, litter and bare soil were determined in each plot. To study the flora of the study area, all plant species in the region were sampled and identified using reliable references. To evaluate species composition in all three sites, plant functional types were used. One-way analysis of variance followed by LSD were used to compare control area, area under microcatchment operation and area under water spreading system in terms of vegetation attributes. The rate of vegetation attributes change was also determined. Detrended correspondence analysis was used to investigate the relationship between plant species and water harvesting operations and control areas.

The results showed that there was a significant differences between water harvesting operations and control areas in terms of bare soil, litter and vegetation (P <0.05) The water spreading system and microcatchment operation had a significant effect on vegetation canopy and litter cover in the region (P <0.05). Examination of plant functional types also showed that palatability classes II and hemicryptophytes had more chance to develop under water harvesting operations respectively. In terms of life form, water harvesting operations had the most positive effect on forbs and grasses, respectively (P <0.05). The results also showed that the families Poaceae, Chenopodiaceae and Fabaceae were successful families in the sites under water harvesting operations, especially the sites under water spreading system. The rate of vegetation attributes change was increasing in the area under water spreading system compared to the area under microcatchment operation, except for the bare soil. The highest and lowest positive changes belonged to litter and Simpson index with a mean of 9.07±0.62 and 0.48±0.25, respectively. The results of DCA showed that Cenchrus pennisetiformis،، ‏Tephrosia persica، ‏Atriplex leucoclada‏ ، ‏Cornulaca monacantha‏ ,‎ ‎Cynodon dactylon were the most important species related to water spreading system and microcatchment operation.

Both water spreading system and microcatchment operations improved the quality and quantity of vegetation in the region, but the effects of water spreading system were greater than microcatchment operation in restoring vegetation. According to the ecological indicators considered in this study, water spreading system is recommended to restore vegetation in arid and semi-arid regions. In the end, it is suggested that economic and social indicators such as the cost of implementing various water harvesting operations should be also considered in future studies, to combine all ecological, economic and social indicators to suggest the best water harvesting operations for rangeland restoration.

Ninety percent of Iran's surface is under arid and semi-arid climates. However, low precipitation and low permeability of soils are considered as some of the most important natural problems of rangelands in such climates that prevent the successful establishment of plants. Therefore, it is necessary to perform a series of mechanical operations to make optimal use of wastewater and to store the rainfall.

a factorial experiment was performed via a completely randomized design with three replications and three treatments, including the rainfall storage structure (in five levels), soil depth (in two levels), and sampling season (in two levels) to compare the two methods of contour furrow and catchment crescents. Accordingly, a total of 60 soil samples were collected, which were immediately weighed after harvest and transferred to the soil science laboratory where their weight moisture content was measured individually. Moreover, a randomized systematic plot method was used to measure forage production and compare it to structural type treatments. In each of the treatments, two 100-meter transects were used at a distance of 100 meters from each other, and the total forage was harvested in 50 plots, whose weights were measured as grams per square meter.

Analysis of variance of the collected data indicated that the main variables' (structure, depth, and sampling season) effect and the interaction effects (structure × depth, structure × sampling season, and structure × depth × sampling season) on the percentage of soil moisture were very significant. Moreover, there was a significant difference (P% 1) between the percentage of moisture's weight in the catchment crescent treatment with contour furrow, and between these two treatments with the other three ones (i.e., between catchment crescents, contour furrow, and control). The analysis of the data also suggested that when measured by the contour furrow method, the soil's moisture was 13.3% and 66.2% higher than the control treatment at the depth of 20-50 cm in the first and second sampling seasons, respectively. on the other hand, when measured by the catchment crescent method, the soil's moisture was 115.9% and 183% greater than that of the control treatment, respectively, indicating that the use of both catchment crescent and contour furrow methods increased moisture storage in deep soil.Furthermore, the study's results showed that the catchment crescents method played a more effective role in soil water storage. It was also found that compared to the contour furrow method, moisture content was increased in the catchment crescents method by 90.5% and 70.4% in deep soil during the spring and autumn, respectively. Moreover, the results suggested that the amount of forage production was significantly different (P≥ 1%) in the catchment crescent treatment, the contour furrow treatment, and the other three treatments, and that the use of both precipitation storage methods increased forage production in the rangeland, with the production of herbaceous plants being increased by 126% in the contour furrow method and 378% in the catchment crescent method, compared to that of the control. Taking the obtained results into consideration, it could be said that the catchment crescent method was 110% more effective in increasing forage production than the contour furrow method.

considering the direct relationship between the percentage of soil moisture and the amount of forage production in rangeland plants, it could be argued that increased moisture storage in the soil induced by the use of rainfall storage methods could have a great effect on increasing rangeland plant production, especially perennials. Taking this study's results into account, it can be said that an increase in moisture storage in deep soil because of the application of the catchment crescent method, and, therefore, its added effect on vegetation characteristics, indicates the higher efficiency of the method over the contour furrow one, for which two reasons can be offered: 1- In the catchment crescent method, the runoff is collected from a larger surface on the upstream slope of the crescents, which is then stored in a small area inside each catchment crescent; 2- The depth of the catchment crescent is more than that of the contour furrow (minimum 50 cm vs. maximum 25 cm), and therefore it stores more runoff inside, giving ample opportunities to the water stored in the catchment crescent so that it can penetrate deep into the soil. Therefore, it can be suggested that the relevant organizations use the catchment crescent method instead of the contour furrow one to store precipitation in the soil so that they can improve and rehabilitate the rangelands.

Land use change, land abandonment, overgrazing, expansion and spread of exotic species are of the most important challenges in the rangelands of the country. For this reason, in this research, it has been attempted to address the challenges by presenting a single improvement solution. Therefore, the perennial rainfedd alfalfa was used for cultivation in degraded rangelands or abandoned lands for both goals of rangeland reclamation and carbon sequestration. Three rangelands were studied in the protected area of Lashgardar-Malayer reclaimed rangeland via alfalfa, medium grazing, and degraded rangelands. In each of these rangelands, sites were selected for sampling. The size and number of plots were determined by the minimal area and statistical method. In each plot, the aboveground and underground biomass and litter were collected. Soil sampling was performed in the plots and the measurement of carbon sequestration was conducted in the laboratory. Soil samples were collected from two layers of 0-15 and 15-30 cm and their carbon was measured. The three study rangelands were compared using a One-Way ANOVA analysis, and the results showed that the amount of carbon sequestration in the rangeland reclaimed  with perennial rainfed alfalfa (36.8 ton / ha) after 4 years was around 1.25 fold higher than the medium grazing rangeland (29.27 ton / ha) and 1.71 fold as compared with the degraded rangeland (21.54 ton / ha). These results indicate that reclamation of degraded rangelands causes to achieve land conservation goals and increase the ability of the ecosystem for carbon sequestration.