جستجوی مقالات مرتبط با کلیدواژه "بنیه و شادابی" در نشریات گروه "آبخیزداری، بیابان، محیط زیست، مرتع"

Rangelands are the largest of the earth''s natural resources that the use of them with proper management can be affordable in terms of economic and agricultural. Due to the successful results of cultivation of some grasses including Bromus tomentellus in Gharabagh of West Azerbaidjan، the determination of allowable use for Bromus tomentellus can be useful in conservation and proper utilization of the mentioned species as well as ensuring its survival. Treatments in each block were four grazing intensities of 25، 50، and 75% and control (no harvest). In each treatment، 10 individuals of species were considered as replications. Data were analyzed in a split plot in time for four years (2007-2010) by SAS & IRRISTAT software. Results showed that the effect of year، different harvesting intensities and interactions between year and different harvesting intensities on forage production and vitality of Bromus tomentellus was significant at 1% level of probability. No significant difference was found between control treatment and grazing intensity of 25 percent as well as 25 and 50 percent. With increasing harvesting intensity to 50 and 75 percent، average rate of production decreased significantly compared to control. Average production and vitality showed a downward trend during 2007-2010 due to the severe reduction of average production and vitality at 75% harvesting intensity. Other treatments including control، 25، and 50 percent، showed almost similar trend during the four years. Based on AMMI analysis، first interaction principle component (IPC1) was significant at 1% level of probability and explained 99. 19% of interaction sum of squares. According to the biplot of first interaction principle component and average production، the least production and stability was obtained at 75% harvesting intensity while maximum stability was recorded for 50% harvesting intensity. According to the results، a harvesting intensity of 50% is recommended for Bromus tomentellus in the region so that health and vitality of this species is preserved during the harvesting years.

Range condition is known as an important indicator for assessment in range management. Many techniques have been exploited for determining this indicator, from which four-factor method has been used in this study. Some communities at stepic regions of Isfahan province were selected. In each selected community, an area was chosen as key area, and a total of eight sites were selected in the key areas. Soil erosion, canopy cover, plant composition, and plant vigor were monitored for each site. The results revealed a significant difference between the sites in terms of the above mentioned parameters, as well as their rainfall (p<0.01). Moreover, there was a significant correlation between annual precipitation and range condition score. The correlation showed different patterns within years in each site, where the difference between years was significant in terms of plant vigor and canopy cover, but non-significant in terms of soil erosion and plant composition. There was also a positive correlation between the trend of individual parameters and the overall condition score. Cluster analysis grouped Aluyjeh, Northern Shahreza, and Charmshahr sites in one branch, Mooteh, Shoorabad, and Golpayegan in another, and finally Komeshcheh and Southern Shahreza in a third branch. The lowest rank for canopy cover, canopy production and soil erosion belonged to Komeshcheh and Southern Shahreza sites. Aluyjeh, Northern Shahreza, and Charmshahr sites were in better condition than the previous group, yet in poor conditions, and the rest of the sites showed the best conditions among study sites. Generally speaking, Isfahan's stepic rangelands are ranked as poor to very poor, while their condition showed a constant trend.