نتایج جستجو برای: 4 criteria were selected including vegetation cover
تعداد نتایج: 4984083 فیلتر نتایج به سال:
Abandonment of arable lands is the starting point of vegetation succession. The trajectory and speed of succession can be different according to the time of abandonment. The aim of this study is to assess the effect of abandonment periods on species richness, diversity and functional groups in shrublands and grasslands of Shirmard rangelands in Chaharmahal va Bakhtiri, Iran. A total of 96 abond...
________________________________________________________________________________ Abstract Grazing levels and rotational schemes need to be tailored to each individual farm or pasture, and more studies are needed on the resilience of rangelands and on separating the effects of grazing and climate. The direct short-term impact of three rates of stocking (4, 8 and 16 Small Stock Units-SSU/ha) was ...
Desertification process has always been led to destruction of vegetation cover and soil and water resources that can occur in different climatic conditions, the intensity of which depends on the natural conditions of the region. Due to the increase in destruction of vegetation as one of the most important consequences of desertification, monitoring the changes and assessment of their trends are...
this study was carried out to investigate the effective environmental factors in the distribution of vegetation in zirkouh rangelands of qaen. after delimitation of the study area, sampling of soil and vegetation were performed using randomized- systematic method. vegetation cover was recorded by using braun-blanquet combined abundance-cover scale in each sample. within each sample, one profile...
Land cover changes significantly influence vegetation greenness in different regions. Dense Landsat time series stacks provide unique opportunity to analyze land cover change and vegetation greenness trends at finer spatial scale. In the past three decades, large reclamation activities have greatly changed land cover and vegetation growth of coastal areas. However, rarely has research investiga...
Water harvesting is the collection of runoff for productivity purposes, instead of runoff being left to cause erosion. In arid and semi-arid drought-prone areas, micro-catchments are widely used as a water harvesting method to improve rangeland condition. The aim of present study was to investigate the effects of micro-catchment on ecological indices of rangeland health in Ghick-Sheikhha, Jirof...
The study of the exclosure effects on the vegetation changes undergrazing and non-grazing conditions in the rangeland areas has particularimportance in the rangeland improvement and revivification projects. Theresearch was accomplished in semi-steppe KhoyBilehvar area, from 1999 to2005. Vegetation cover was annually measured within fixed plots during transact.The results showed that during nine...
The Qinghai-Tibetan Plateau (QTP) contains the largest permafrost area in a high-altitude region in the world, and the unique hydrothermal environments of the active layers in this region have an important impact on vegetation growth. Geographical locations present different climatic conditions, and in combination with the permafrost environments, these conditions comprehensively affect the loc...
This research was aimed to simulate and prioritize the effective factors on water erosion using USLE-M in the system dynamic model. In this integrated model, by using the system dynamic simulation software (Vensim), all variables and factors involved in erosion and soil loss were considered according to the USLE-M model. After model implementation, the estimated values and observations were com...
this is an original study on the effect of a polyisobutylene – polydimethylsiloxane (pibpdms) block copolymer modifier used as an interfacial active agent on the dynamics behaviour of single newtonian drops suspended in a polyisobutylene (pib) newtonian matrix. the results were divided in two sections. the first part included the experiments carried out on the non-modified and 2% block cop...
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