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Introduction: water is necessary for human, animal and vegetation life. Therefore providing enough water is undeniable to sustain creature life. Water development supplies should be undertaken in such a way as to keep the hydrological balance and biological functions of all ecosystems, which is crucial for marginal lands. Precipitation storage is the general name used for all different techniques which collect runoff and rain water to be saved in the soil profile or tanks and used for the production of trees, crops and development of them in dry land. The precipitation storage is applied for afforestation in arid and semi-arid regions which rainfall is not enough to sustain a good seedling or tree growth. Precipitation storage can increase the rate of tree establishment in drought regions by collection of rainfall and runoff enhancement. Therefore, by using these techniques, we can improve the lack of soil moisture and overcome good spells in critical growing stages and so secure good water for plant when rainfall is erratic. So the aim of this study was to investigate the effect of different precipitation storage techniques on soil moisture preserve and some growth characteristics of Acacia oerfota (Forssk.) Schweinf seedlings in Paired watershed of Dehgin, Hormozgan province.
Material and methods: Paired watershed of Dehgin is one of the sub watersheds of Esteghlal dam in Minab, Hormozgan province. After collection of Acacia oerfota seeds in the summer of 2018, we planted them in plastic pots. Collar diameter, Stem height and quality characteristics of seedlings were measured. Then seedlings were planted with three replications (three blocks) in four treatments (diamond-shape micro catchment, semi-circular bunds, pitting and control). After four months and five rainfall events, growth and quality characteristics of seedlings were measured in different precipitation storage techniques and analyzed using two way analysis at the level of 95%. Soil moisture between different precipitation storage techniques and control was measured and analyzed using two way analysis. Also the relationship between soil moisture, collar diameter and stem height were measured using Pearson's correlations.
Results: Results Showed seedling vitality in control with the amount of 2.86 was significantly lower than it in different precipitation storage techniques. Collar diameter of seedlings in semi-circular bunds (1.95 mm) was higher than it in diamond-shape micro catchment, pitting and control (0.92, 0.88 and 0.89 mm). Height growth in semi-circular bunds with the amount of 10.12 cm was significantly higher than it in control with the amount of 6.2 cm. These significant differences were due to the function of different precipitation storage techniques. Soil moisture percentage in all treatments was different (p<0.05). The amounts of soil moisture were 13.46%, 11.95%, 11.5% and 10.34% in diamond-shape micro catchment, semi-circular bunds, pitting and control respectively. Also soil moisture has positive direct effect on collar diameter and seedling height (p<0.01).
Discussion and Conclusion: Vitality and establishment of tree seedlings depend on soil conditions and available moisture. Rain water is great for plant growth because it is free of salts and other minerals that may harm plants and prevent their growth. As rain water percolates into the soil, it forces salt down and away from root zone, so it allows roots to grow better and makes them tolerate higher drought. Construction of diamond-shape micro catchments, semi-circular bunds and pitting in the study region, collection of rain water and runoff, increased soil moisture by improving infiltration rate, and facilitated plant growth. Plants need large quantities of water for growth. Water was used during photosynthesis to produce carbohydrate which is necessary for plant growth. As we know leaves are important organs for photosynthesis and play an important role in survival and growth of plants. In according to results soil moisture was higher than that in control so we can conclude lower growth in control is due to lower moisture.
The results of this study showed precipitation storage techniques are very important methods for soil moisture storage to improve vegetation in arid and semi-arid area and also increase growth and vitality of them. According to the study results, soil moisture content and also growth characteristics of drought-tolerant seedlings of Acacia oerfota, were higher in semi-circular bunds than to those in control and other precipitation storage methods. These seedlings have a suitable shoots, large and green leaves without dieback in dry climate of Dehgin which is the result of rain water and runoff collection by precipitation storage techniques and absorption of it by plants. According to the results, among all treatments, semi-circular bunds is the best precipitation storage methods for afforestation and pasture improvement in the studied region.    
Type of Study: Research | Subject: Forestry
Received: 2019/05/21 | Accepted: 2019/10/20