Effects of past land use on soil organic carbon changes after dam construction

Ya Li; Jinming Hu; Xu Han; Yuxiang Li; Yawen Li; Baiyun He; Xingwu Duan

doi:10.1016/j.scitotenv.2019.06.030

Effects of past land use on soil organic carbon changes after dam construction

Sci Total Environ. 2019 Oct 10:686:838-846. doi: 10.1016/j.scitotenv.2019.06.030. Epub 2019 Jun 4.

Authors

Ya Li¹, Jinming Hu², Xu Han¹, Yuxiang Li¹, Yawen Li¹, Baiyun He¹, Xingwu Duan³

Affiliations

¹ Institute of International Rivers and Eco-security, Yunnan University, Kunming 650091, China.
² Institute of International Rivers and Eco-security, Yunnan University, Kunming 650091, China; Yunnan Key Laboratory of International Rivers and Trans-boundary Eco-security, Kunming 650091, China.
³ Institute of International Rivers and Eco-security, Yunnan University, Kunming 650091, China; Yunnan Key Laboratory of International Rivers and Trans-boundary Eco-security, Kunming 650091, China. Electronic address: xwduan@ynu.edu.cn.

PMID: 31195291
DOI: 10.1016/j.scitotenv.2019.06.030

Abstract

A large-scale and high-dropout water-level-fluctuation zone (WLFZ) was formed by the construction of cascaded large dam in the southwest hydropower base of China. The original land use patterns changed significantly by the formation of the WLFZ, which possibly affected the soil organic carbon (SOC) stocks and local carbon cycle. However, little is known about the effects of land uses before dam construction on the SOC stocks in the WLFZ. To address this, we chose the Nuozhadu mega reservoir built in 2014 in the upper Mekong River basin as our study area. We established five sampling transects around the reservoir and sampled them in 2015. Each transect contained three vertical sampling lines representing three land-use types: natural forest, farmland, and rubber plantations. SOC stocks were determined in the WLFZ and in the infralittoral reference zone (IRZ), and the interactions among SOC, land uses, soil erosion, inundation, and other soil physicochemical properties were analyzed to establish the factors controlling SOC in the WLFZ. The average soil organic carbon density (SOCD) was not significantly different between the WLFZ and IRZ, but it differed significantly among the three types of land uses. The SOC stocks in natural forests of the WLFZ and IRZ were significantly greater than those in the other land use types. The SOCD decreased with increasing elevation in the natural forest and rubber plantation in the WLFZ, while no significant trend was found in farmland. These results indicated that the construction of a large dam in southwestern China may not lead to significant changes in regional SOC stocks, but it can result in the redistribution of SOC in the large-scale and high-dropout WLFZ. Land use before dam construction can affect the background concentrations of SOC, soil physicochemical properties, and soil erosion rate in the WLFZ, which controlled the redistribution of SOC.

Keywords: Hydropower base; Land uses; Soil erosion; Soil organic carbon; Water-level-fluctuation zone.