Growth and Nutrient Status of Introduced Black Locust (Robinia pseudoacacia L.) Afforestation in Arid and Semi Arid Areas of Iran

Under global climate change it is expected that many arid regions in the world will experience enhanced desertification in the next decades. Black locust (Robinia pseudoacacia L.) is a one commonly used species for afforestation projects in arid regions of Iran due to its soil rehabilitation capabilities. This study aims to characterize how Robinia growth parameters and nutrient status interacted and were influenced soil properties. The experiment was conducted at three Robinia plantations in Iran, across a water and nutrient availability and salinity gradient. Sample plots (20x20 m) were set up at each Robinia study site in order to measure growth rate and to take leaf, stem and soil samples. Total concentration of macro and micro nutrients in soil and organic samples and also soil exchangeable cations were measured using ICP-OES. Robinia growth showed a positive correlation with soil organic carbon, total nitrogen, total phosphorus and Cation Exchange Capacity (CEC) and a negative relationship with soil inorganic carbon. In the study site with higher Exchangeable Sodium Percentage (ESP) Robinia absorb more exchangeable potassium than sodium as an adaptation mechanism against soil salinity. The concentration of nitrogen (N), sodium (Na) and calcium (Ca) of leaves was fairly good reflecting the variation in soil element concentrations under Robinia plantations. Consequently, mentioned soil properties can be applied practically as indicators for understanding the success or failure of Robinia afforestation projects in Iran and similar regions in the world.