Hydrological Effect of Natural and Planted Forest Stands in the Zagunao Watershed of the Minjiang River Basin

In this study, the water holding capacity of ground cover and soil layer of 4 natural forest stands and 3 planted forest stands in the Zagunao watershed were investigated through field measurements and laboratory experiments. The results show that there was a significant difference in the maximum water holding capacity of ground cover in different forest stands (natural coniferous forest > natural coniferous and broad-leaved mixed forest > dense planted coniferous forest > natural deciduous broad-leaved forest > natural evergreen/deciduous broad-leaved forest > planted-natural coniferous and broad-leaved mixed forest > sparse planted coniferous forest); 0–20 cm soil saturated water holding capacity was significantly different among 7 forest stands (natural coniferous forest > natural coniferous and broad-leaved mixed forest > planted-natural coniferous and broad-leaved mixed forest > dense planted coniferous forest > sparse planted coniferous forest > natural evergreen/deciduous broad-leaved forest > natural deciduous broad-leaved forest); Soil water conservation capacity was much greater than the ground cover water conservation capacity for all forest stands. The natural water content and maximum water holding capacity of natural forest ground covers were about 1.26 and 1.24 times of that of planted forests, respectively. Among the 3 types of planted forests, hydrological indicators of the ground cover except for the natural moisture of sparse planted coniferous forests were lower than those of the other 2 planted forest stands; The dense planted forest stand had the highest maximum water holding capacity and the effective holding capacity of ground cover; 0–20 cm soil saturated water holding capacity and non-capillary water holding capacity of planted-natural coniferous and broad-leaved mixed forest was the highest. Given that the soil layer is the major contributor to regional water conservation, the mixture of coniferous and broad-leaved trees should be adopted in forest plantation, which helps in improving the forest structure, enriching understory plants of planted forests and enhancing water holding capacity of forest ground cover and soil layer.