Preliminary study of Pistachio forests (Pistacia vera)in Khorassan
1996
Ramezani, Mostafa
Pistachio trees (Pistacia vera) have formed natural forests in some regions of Khorasan province. These forests are one of the most value genetically resources in Iran. According to our study, these forests cover approximately 20000 ha. Area. Pistachio trees were mainly distributed in Ostai, Khajeh and Shorlogh regions. Another regions of distribution including marginal regions of Iran and Afghanistan and Turkmenistan and then are continued into these countries. Altitude changes of this species ranges from 650 to 1700 meters and amount of precipitation is 200-250 mm in these growth regions. At the present time, in spite of grazing pressure and erosion effect on loess particles of soil, the role of pistachio trees in protection of soil and prevention of the erosion, especially stabilization of loess, is very important.In view of geology organization, this species generally, established on chehel-kaman formation and loess sedimentsand in some region on kashaf rood formation. In addition to altitude, main bed stone, direction, slope and loess thickness in growth zones of Pistachio, are the main factors to density and distribution of this species. Economically amount of Pistachio production in the forest, are not consider able and it is estimated that is nearly 200-400 kg/ha. This problem is due to effect of environ mental factors, lock of protection, alternation of year- production and considerable numbers of male trees in relation to female ones. (in some region the relation is exceeded to 50%). Presently, pest damages in growth regions of Pistachio are very remarkable and mainly are due to destructive effects of leaf hopper (Idiocerus stalli), Aphid gall (Fora hirsula) , psyllid (Agonosena viridis) and. Gelechia cuneatella.
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