Rainwater harvesting as a tool to recover the declining Juniper ecosystem
The juniper ecosystem has been declining progressively. The indications were dieback, mortality and lack of sufficient regeneration.
Does water stress play any role in the process of decline? Is it possible to recover the ecosystem by improving rainwater harvesting?Three types of microcatchments were established namely; terraces, semi-circular bunds and quadrangular bunds.
The efficiency of three structures of rainwater harvesting namely: terraces, quadrangular and semicircular bunds was investigated in Al Souda National Park (southwestern Saudi Arabia, 18° 17´ 59´´ N 42° 21 47´´ E). The study area was dominated by Juniperus procera Hochst. ex Endlicher trees. Terraces, quadrangular and semicircular bunds significantly reduced runoff (8.6, 12.3 and 8.8 L/ha, respectively) as compared to control (19.6 L/ha). Also terraces, semi-circular and quadrangular bunds significantly reduced soil erosion (87.1, 75.3 and 31.0 kg/ha, respectively) as compared to control (109.6 kg/ha). Porosity percent was significantly higher in quadrangular, and semi-circular bunds and terraces (38.9, 38.8, and 37.4%, respectively) than in control (26.3%). Similarly, soil bulk density was maximum in control (1.90 g/cm³) as compared to repaired terraces (1.62 g/cm³), quadrangular and semicircular bunds (1.69 and 1.66 g/cm³, respectively). Soil moisture content percent (MC %) significantly increased in all microcatchments compared to control. The increase in soil MC % was maximum at 5 cm soil depth, moderate at 15 cm and least at 30 cm soil depth. Improvement of soil and water conservation by microcatchments caused significantly more growth and survival of seedlings of J. procera as compared to control ( 7.0 and 4.8 cm in diameter; 46.3 and 24.8 cm in height; and 86.8 and 55.4% survival rate in seedlings in microcatchments and control, respectively). Thus, Microcatchments have played an important role in recovering the Juniper ecosystem in Saudi Arabia.