Journal Article

Differential magnitude of rhizosphere effects on soil aggregation at three stages of subtropical secondary forest successions

Yan, Enrong, Wang, Jiawei, Bai, Shahla Hosseini, Shao, Junjiong, Wang, Xihua, Zhou, Xuhui, Liang, Chao, Fu, Yuling, Liu, Ruiqiang, Chen, Xiaoyong

2019

Overview

Background and aims Roots and their rhizosphere considerably influence soil structure by regulating soil aggregate formation and stabilization. This study aimed to examine the rhizosphere effects on soil aggregation and explore potential mechanisms along secondary forest successions. Methods Effects of roots and their rhizosphere on soil aggregation in two subtropical secondary forest successions were examined by separating soils into rhizosphere and bulk soils. Soil aggregate mean weight diameter (MWD), soil organic carbon (SOC), soil nutrients, and fine-root traits were simultaneously measured. Results Soil aggregate MWD increased significantly in the bulk soils along secondary forest successions, but did not differ in the rhizosphere soils. Rhizosphere effects on soil aggregate MWD (i.e., root-induced differences between the rhizosphere and bulk soils) were thus significantly higher at the early-successional stage of subtropical forest with low soil fertility than those at the late stages with high fertility. Rhizosphere significantly increased SOC and soil total nitrogen (TN) throughout the entire secondary forest successions, which was nonlinearly correlated with soil aggregate MWD. Principal components regression analysis showed that SOC was the primary abiotic factor and positively correlated with soil aggregate MWD. As for biotic factors, fine-root length density and N concentration were two important root traits having significant effects on soil aggregate stability. An improved conceptual framework was developed to advance our understanding of soil aggregation and rhizosphere effects, highlighting the roles of soil fertility (i.e., SOC and available nutrients), root traits, and forest age in driving soil aggregation. Conclusions Impacts of root-derived organic compounds inputs to rhizosphere on soil aggregation were stronger at the early-successional stage of subtropical forest than those at the late stages. This succession-specific pattern in rhizosphere effects largely resulted from the nonlinear relationships between soil aggregate MWD and SOC concentration with a plateau at high SOC. Incorporating the SOC-dependent rhizosphere effects on biogeochemical cycle into Earth system models might improve the prediction of forest soil C dynamics.

• Publisher: Springer Science + Business Media,Springer International Publishing,Springer,Springer Nature B.V
• Subject: Abiotic factors / Agglomeration / aggregate stability / Biogeochemical cycles / Biomedical and Life Sciences / Biotic factors / Ecological succession / Ecology / Ecosystem components / Environmental aspects / environmental factors / fine roots / Forest soils / Forests / Life Sciences / Nitrogen / Nutrient availability / Nutrients / Organic carbon / Organic compounds / Organic soils / Plant Physiology / Plant Sciences / prediction / Regression analysis / REGULAR ARTICLE / Rhizosphere / Roots / secondary forests / Soil aggregates / soil aggregation / Soil carbon / Soil dynamics / Soil fertility / Soil improvement / Soil nutrients / soil organic carbon / Soil Science & Conservation / Soil stability / Soil stabilization / Soil structure / Soils / total nitrogen / Tropical forests / Weight