Reza Bagheri; Mohsen Mohseni Saravi; Mohammad Reza Chaichi
Volume 20, Issue 2 , June 2013, , Pages 417-432
Omol banin Bazr afshan; Mohsen Mohseni saravi; Arash Malekian; Abalfazl Moeini
Volume 18, Issue 3 , September 2011, , Pages 395-407
Abstract
Drought is defined as the continuous and abnormal moisture deficit. The term of continuous means continuation of deficit and the term of abnormal means deviation of favorite index of natural condition from the mean. In every drought study four main characteristics are considered: severity, duration, ...
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Drought is defined as the continuous and abnormal moisture deficit. The term of continuous means continuation of deficit and the term of abnormal means deviation of favorite index of natural condition from the mean. In every drought study four main characteristics are considered: severity, duration, frequency or return period and areal extent. The objective of this investigation is mapping drought severity in Golestan province. For this purpose, Standardized Precipitation Index (SPI) was used for drought monitoring in some meteorological stations located in Golestan province. This index was computed in a period of 25 years precipitation data (1975-2000) at four different time scales including 6,9,12, and 24 months. Consequently, the most sever drought in 6 month time scale was observed in Saliantapeh station while the highest severity in 9, 12, and 24 time scales was observed in Polejadeh station. The aerial extent SPI values for the most severe drought condition in different time scales were classified in Golestan province using geostatical techniques. The results showed that the area affected by drought decreased with increasing drought duration and the condition of drought in the province had west-east direction
Reza Bagheri; Mohammad reza Chaichi; Mohsen Mohseni Saravi
Volume 17, Issue 2 , September 2010, , Pages 301-316
Abstract
This research was studied in order to determining grazing intensity effects on soil moisture and vegetation in Khabr region of Kerman province for two years. Natural sites under three grazing pressures (heavy, moderate and non grazed) with same ecological factors were selected from Khabr National Park ...
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This research was studied in order to determining grazing intensity effects on soil moisture and vegetation in Khabr region of Kerman province for two years. Natural sites under three grazing pressures (heavy, moderate and non grazed) with same ecological factors were selected from Khabr National Park and near rangelands. After determining sampling area, soil moisture factor was investigated monthly (on grazing period) in 0-15 and 15-30 centimeters depth of each site with 5 replication and canopy cover sampling was conducted in three temporal stages (before, middle and after grazing) using line transect method in three replication for each site. SPSS package was used for statistical analysis. Result showed that heavy grazing reduced total canopy cover, specialy perennial grass and shrubs, than non grazed site in the end of grazing period. Also heavy grazing reduced the soil moisture content with decreasing rate as 16.87% and 25.07% , than moderate and non grazed sites , respectively. Harmful effect of drought in 2006 was severly affected on heavy than moderate and non grazed site. According to results, non and moderate grazed sites occure in state condition (due to more canopy cover of Artemisia sieberi and other species such as prennial grass) and heavy grazed site occure in transition to downward state condition (due to one dimentional dominant of Artemisia sieberi and emergence of undesirable species such as Marrobium vulgaris and Peganum harmala) in state and transition model of Iranian Artemisia habitat. Thus, without management plan, we will observe dominance of undesirable species and rangelands degradation.