Oriental beech roots improve soil aggregate stability and reduce soil detachment rate in forest lands

Abstract

In many forestlands, such as Saravan Forest Park, the high capacity of soil detachment from deforestation and subsequent ecological restoration are important issues that need detailed information about plant and tree species for the objectives of soil conservation. To determine if some species are more helpful for the stability of soil aggregates and thus reducing soil erosion, we examined Oriental beech species, compared to three other species (Crataegus ambigue, Primula heterochroma and Rubus persicus) in the Saravan forest park, and measured how root characteristics (root biomass, root length and root weight density) influenced mean weight diameter of aggregates (MWD) and soil detachment rate (Dc). For measuring Dc, undisturbed samples collected from soils under the four studied species and subjected to five slopes (from 4.8 to 31.4%) and five water discharges (from 0.26 to 0.65 l m−1 s−1) by a hydraulic flume. Results showed that Oriental beech roots can significantly influence soil aggregate stability. MWD was greater in soil under Oriental beech species characterized by high values of root biomass, root length and root weight density. Moreover, Dc was significantly lower in soils with Oriental beech species compared to three other species. Pearson's correlation matrix showed a strong positive correlation between MWD and the root characteristics (P < 0.01) (R2 = 0.8). Also, the clustering of soils among the studied species by the principal component analysis (PCA) revealed a clear difference based on the root characteristics and MWD. Generally, this study showed that, compared with other species, the root system of Oriental beech is more effective in the stabilization of slope by the binding effect on the soil, thus improving aggregate stability and reducing soil detachment rates.