Effects of using water harvesting and organic mulch on afforestation success of Periploca aphylla Decne in the desert region of southern Iran

In the south of the country, due to the harsh habitat conditions and the lack of natural forests compared to other regions of the country, the issue of forest plantation is of particular importance. Considering the severe decrease in soil moisture due to the decrease of rain in recent years, the outflow of runoff during the growing season and the inappropriate distribution of rainfall in the southern and dry regions of Iran, the use of catchment systems can be an important factor in the establishment and vegetative growth of seedlings in the dry areas of southern Iran. The purpose of this research is to investigate the effect of different drainage systems along with natural mulch on the vegetative characteristics of P. aphylla seedlings.

For this purpose, P. aphylla seedling in two levels of mulch (with organic mulch and no mulch) and water harvesting system in four levels (crescent, pitting, negarim system and control), in block randomized design as split plots were designed in the field (120 seedlings = (5 repetitions) number of seedlings × (2) mulch area × (4) number of systems × (3) repetition or number of blocks). Humidity was measured 24 hours after each rainfall over three years. Vegetative characteristics (viability, canopy length, canopy area, collar diameter growth and height growth) and vigority of all seedlings were also measured and analyzed using GLM test.

The results showed that the percentage of survival and canopy area of P. aphylla species was the highest with 100% and 1282.74 square centimeters respectively in pitting and crescent systems. The highest percentage of soil moisture with 22.14% was obtained in the negarim system. In general, regardless of the type of system, the percentage of soil moisture in the mulch treatment (21.66%) was higher than the no-mulch treatment (16.14%). The results of interaction effects showed that the canopy area and the growth height in the mulching system have the highest values of 1920.68 cm2 and 48.92 cm in the pitting system.

The results of the present research indicate the optimal performance of different methods of storing precipitation in collecting, storing and maintaining moisture in the Dehgin region, which gradually provides moisture to the plant gradually. After 3 years, results showed that the growth of P. aphylla seedling was better in water catchments especially in pitting system. Also seedling growth was better in water catchments that used organic mulch . Organic mulch is an effective factor which protects soil moisture in the root area. According to different performances of investigated factors, suggest that pitting system with organic mulch and native species should be used in Dehgin and habitats like that in the South of Iran.