Ali Ehsani; Hosein Arzani; Mahdi Farahpur; Hassan Ahmadi; Mohammad Jafari; Mortezah Akbarzadeh
Volume 19, Issue 1 , June 2012, , Pages 1-16
Abstract
In this study, potential and actual evapotranspiration were estimated by Penman- Matis using climatic data of Saveh Station, and plant and soil characteristics were estimated by Cropwat 8.0 software. Our results showed that potential evapotranspiration in growing season was 6.16 times greater than the ...
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In this study, potential and actual evapotranspiration were estimated by Penman- Matis using climatic data of Saveh Station, and plant and soil characteristics were estimated by Cropwat 8.0 software. Our results showed that potential evapotranspiration in growing season was 6.16 times greater than the average of actual evapotranspiration. Actual evapotranspiration was 1.18 times greater than the average precipitation of growing season. It means that plant species have used the stored moisture for actual evapotranspiration. According to the estimation of actual evapotranspiration in a ten-year period, a model was provided for forage production as Ya= 74.30+ 2.698 (ETact). Accordingly, average forage production of the studied site was estimated as 257 kg/hec. It could be said that actual evapotranspiration as an index for climate yield is one of the fundamental factors in improving water use efficiency. Application of the mentioned climate index in different estimation models of long term forage production could be considered in order to determine the rangeland grazing capacity and developing rangeland insurance as a replacement for the usual methods of production.
Mirtaher Ghaemi; Mortezah Akbarzadeh; Shahram Abedi
Volume 19, Issue 1 , June 2012, , Pages 82-94
Abstract
Study of exclosure effects on vegetation changes under grazing and no grazing conditions in rangelands is of particular importance in range improvement programs. The reseach was performed in Semi- Steppe area of Bilehvar, Khoy from 1998 to 2006 . The vegetation cover was measured every year inside fixed ...
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Study of exclosure effects on vegetation changes under grazing and no grazing conditions in rangelands is of particular importance in range improvement programs. The reseach was performed in Semi- Steppe area of Bilehvar, Khoy from 1998 to 2006 . The vegetation cover was measured every year inside fixed plots along the transacts. The results indicated the increase of total canopy cover inside the exclosure occurred during 9 years of the study, where the highest increase rates were observed with perennial cereals (>3.5 times), and with perennial broad-leaf forbs (>2.5 times). Outside the exclosure, the total canopy cover approximately remained unchanged and vegetative forms showed less changes. Inside the exclosure, favorable species appeared with a vegetation composition of about 19% . The proportion of increasers in the vegetation composition increased to more than double, however non-favorable species decreased to half. Outside the exclosure, desirable species were rare and the proportion of increasres increased to 28%. Average vegetation cover of annual plants inside the exclosure was higher than that of the outside, while average vegetation cover of the forbs compared to annual cereals were more predominant inside and outside the exclosure. During the study (9 years) in Bilehvar, a significant correlation was found between precipitation changes and canopy cover of the most species.