The effect of rainwater harvesting approach to combat drought in the Zagros forests, Iran

Despite their vital role in the sustainability of agriculture, the environment, and human life, the Zagros oak forests are facing severe anthropogenic deforestation and climate change. The purpose of this study was to harvest rainwater and store it in the soil to deal with drought in the Zagros forests, which is part of the forests of Southeastern Kermanshah province. The experiment was conducted as a randomized complete block design with four treatments including crescent-shaped bound with preservation (CSB+P), preservation treatment (PT), crescent-shaped bound without preservation (CSB-P), and control treatment (CT). The results showed that CSB+P treatment attributed to the re-growing of some dried trees (19 tree ha-1) and the reduction in dieback rate (36.7 tree ha-1), and in total 55.7 ha-1 trees in the Zagros forests. Therefore, both the reduction of dieback rate and re-growing of dried trees are two main positive effects demonstrated by the CSB+P treatment. There is no effect of PT treatment on the re-growing trees, while it contributes to the reduction of dieback severity (37.7 tree ha-1). Finally, the CSB-P treatment has the lowest effect among other treatments on dieback reduction (6 tree ha-1). The results also showed that after three years, the soil organic carbon (SOC) in the CSB+P, PT, CSP-P, and CT treatments were 3.25, 2.90, 2.05, and 1.90 %, respectively. In addition, the SOC increased significantly in the CSB+P and PT treatments (P <0.05). CSB+P significantly reduced bulk density (BD) from 1.46 (1st year) to 1.31 (3rd year) enhancing soil moisture content from 16.53 to 19.17%. The CSB+P and PT are significantly improved the SOC, BD, and soil moisture content. It was concluded that forest soil should be protected and in our experience, rainwater harvesting through micro-catchment was the simple and effective short-term technique for increasing soil moisture and consequently combating forest drought in the Zagros regions of Iran.