Unraveling the Influence of Land-Use Change on δ13C, δ15N, and Soil Nutritional Status in Coniferous, Broadleaved, and Mixed Forests in Southern China: A Field Investigation

Taimoor Hassan Farooq; Xiaoyong Chen; Awais Shakoor; Yong Li; Jun Wang; Muhammad Haroon U Rashid; Uttam Kumar; Wende Yan

doi:10.3390/plants10081499

Unraveling the Influence of Land-Use Change on δ¹³C, δ¹⁵N, and Soil Nutritional Status in Coniferous, Broadleaved, and Mixed Forests in Southern China: A Field Investigation

Plants (Basel). 2021 Jul 21;10(8):1499. doi: 10.3390/plants10081499.

Authors

Taimoor Hassan Farooq^{1

2

3}, Xiaoyong Chen^{2

4}, Awais Shakoor⁵, Yong Li^{2

3}, Jun Wang^{2

3}, Muhammad Haroon U Rashid⁶, Uttam Kumar⁷, Wende Yan^{2

3}

Affiliations

¹ Bangor College China, a Joint Unit of Bangor University, Wales, UK and Central South University of Forestry and Technology, Changsha 410004, China.
² National Engineering Laboratory for Applied Technology in Forestry and Ecology in South China, Central South University of Forestry and Technology, Changsha 410004, China.
³ College of Life Science and Technology, Central South University of Forestry and Technology, Changsha 410004, China.
⁴ College of Arts and Sciences, Governors State University, University Park, IL 60484, USA.
⁵ Department of Environment and Soil Sciences, University of Lleida, Avinguda Alcalde Rovira Roure 191, 25198 Lleida, Spain.
⁶ College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
⁷ College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China.

Abstract

Natural isotopic abundance in soil and foliar can provide integrated information related to the long-term alterations of carbon (C) and nitrogen (N) cycles in forest ecosystems. We evaluated total carbon (TC), total nitrogen (TN), and isotopic natural abundance of C (δ¹³C) and N (δ¹⁵N) in soil and foliar of coniferous plantation (CPF), natural broadleaved forest (NBF), and mixed forest stands at three different soil depths (i.e., 0-10, 10-20, and 20-40 cm). This study also explored how soil available nutrients are affected by different forest types. Lutou forest research station, located in Hunan Province, central China, was used as the study area. Results demonstrated that the topsoil layer had higher TC and TN content in the mixed forest stand, resulting in a better quality of organic materials in the topsoil layer in the mixed forest than NBF and CPF. In general, soil TC, TN, and δ¹⁵N varied significantly in different soil depths and forest types. However, the forest type did not exhibit any significant effect on δ¹³C. Overall, soil δ¹³C was significantly enriched in CPF, and δ¹⁵N values were enriched in mixed forest. Foliar C content varied significantly among forest types, whereas foliar N content was not significantly different. No big differences were observed for foliar δ¹⁵N and δ¹³C across forest types. However, foliar δ¹³C and δ¹⁵N were positively related to soil δ¹³C and δ¹⁵N, respectively. Foliar N, soil and foliar C:N ratio, soil moisture content (SMC), and forest type were observed as the major influential factors affecting isotopic natural abundance, whereas soil pH was not significantly correlated. In addition, forest type change and soil depth increment had a significant effect on soil nutrient availability. In general, soil nutrient availability was higher in mixed forest. Our findings implied that forest type and soil depth alter TC, TN, and soil δ¹⁵N, whereas δ¹³C was only driven by soil depth. Moreover, plantations led to a decline in soil available nutrient content compared with NBF and mixed forest stands.

Keywords: C and N cycling; isotopic composition; soil health; stable isotope; vegetation type.

Grants and funding

70702-45200003/Postdoctoral funding from Central South University of Forestry and Technology and the Hunan province finance department