Soil properties and infiltration rate in sago palm (Metroxylon sago) forest in Rongkong Watershed South Sulawesi

Abstract

Sago palm, one of the dominant wetland vegetation in the Rongkong Watershed, contributes to groundwater recharge through its ability to pass water into the ground. This study aims to determine the effect of sago forest canopy density on the infiltration rate in the middle and downstream zones of the Rongkong Watershed in South Sulawesi. Other independent variables were soil texture, permeability, bulk density, porosity, soil organic matter, initial soil moisture, water level, air temperature, and air humidity. The relationship between the independent variables on the infiltration rate was analyzed using multiple linear regression. Infiltration rate observes with ponded infiltration method at five density classes of sago forest. The results showed that the infiltration rate in the middle stream increased along with the increase of density classes of sago forests. The downstream, on the other hand, has an insignificant difference between density classes. The result of the regression analysis showed that the coefficient of determination in the middle and downstream zones was 64.5 % and 38.5 %, respectively. The simultaneous test of variable significance in the middle stream shows that the sago forest canopy density, groundwater level, initial soil moisture, and air humidity significantly affect a p-value <0.05.