Abstract
The Juniperus procera natural stands are an important part of the forest ecosystems in highlands across the world. Al-Sauda Park, Asir region, Saudi Arabia, which is one of the most interesting tourism area in the Arabian Gulf Countries, lies in the highest altitude in the Middle East. The dominant plant species in Al-Sauda Park is Juniperus procera, which has being threatened by dieback disease due to soil erosion by rainwater runoff. In this concern, seven water-harvesting techniques (WHTs) were applied in Al-Sauda Park. The effects of WHTs on 21 physiochemical properties of the soil at two depths (0-10 and 10-30 cm) were addressed. The WHTs include micro-catchment types (semicircular bunds (SCB) and square bunds (SB)) and terraces types (old terraces (OT), new terraces (NT) new terrace and plough (NTP), new terraces and mulch (NTM) and new terraces with both mulch and plough (NTMP)). The means of the levels of physiochemical properties were as follows: moisture content (MC) 0.30; bulk density (BD) 1.82 g/cm3; porosity 31.22%; organic matter (OM) content 3.10 mg/kg; pH 7.49; electrical conductivity (EC) 0.59 dS/m. The means of element contents (mg/kg) were as follows: N 96.05; P 16.75; K 27.20; Mg 88.63; Al 40.30; Ca 391.95; Cr 1.45; Mn 2.76; Fe 173.55; Co 0.09; Ni 0.21; Cu 0.50; Zn 0.42; Cd 0.007; Pb 0.15. Significant effects of WHTs on MC, BD, OM contents, EC, besides the contents of Al, Ca and almost all heavy metals were observed. OT and NTM addressed unpolluted to moderately polluted levels by heavy metals using the geoaccumulation index. Cluster analysis reported the following order of the pairs of soil depths in term of WHTs from nearer to farer: OT > NT > NTM > SB approximate to SCB > NTPM. The principal component analysis extracted the 21 examined parameter to five main components showing various significant inter-relationships.