Estimating water requirement of Prosopis juliflora at different habitates of Persian Gulf - Aman Sea region of Iran

Forest plantation with Prosopis juliflora at southern coastal provinces of Islamic Republic of Iran for sandy dune stabilization، transferred the region to green forests with relatively high stand and crown cover density. Conservation and development of such wide extant area، requires advanced knowledge and information of this species، particularly its water requirement. In this study، water requirement of P. juliflora at eight sites of the region، started from Ahwaz and ended in Chabahar cities، was determined، using together Cropwat 8- FAO Penman-Monteith and WUCOLS III methods. Two important parameters for calculating water requirement for each plant species are: the reference evapotranspiration and crop coefficient. The reference evapotranspiration and crop coefficient were calculated using the mentioned methods، respectively. In recent method، instead of using crop coefficient، landscape coefficient was applied which is usually calculated by considering three factors، including plant species، plant density and micro-climate. The required climatical data for calculating the reference evapotranspiration were obtained from the nearest stations to the P. juliflora plantations. Soil profiles were applied at the forest plantations sites in order to study soil texture and root depth of one or two year old seedlings. The species phenology was defined، using the available references and information. After collecting the required data and calculating the reference evapotranspiration (ETO) and the landscape coefficient، water requirements for P. juliflora at the eight sites were calculated. Results showed that the highest and the lowest required supplement irrigation belonged to the sites Dasht-e Azadegan (255 mm for seven months of a year) and Chahbahar (174 mm for nine months of a year)، respectively. The maximum and the minimum required monthly supplement irrigations for Dasht-e- Azadegan were 52 and 9 mm at July and April، respectively، whereas for Chahbahar were 29 and 5 mm at May and March، respectively and for Bandar Abbas site were 33 and 12 mm in June and November، respectively. It might be concluded that the required supplement irrigation for P. juliflora differs due to variation in site characteristics and variation in months of the year، but unfortunately there was less attention and consideration to that fact by the executive organizations of the country.