Variations in soil carbon, nitrogen, and phosphorus concentrations and stoichiometry with stand age in Acacia hybrid plantations in Southern Vietnam

MAIHAI CHAU (Faculty of Agronomy, Vietnam National University of Forestry. Dong Nai Campus, No. 98 Tran Phu, Trang Bom Town, Trang Bom District, Dong Nai 76000, Vietnam)
NGUYENVAN QUY (Southern Branch of Joint Vietnam-Russia Tropical Science and Technology Research Center. No. 3, 3/2 Street, District 10, Ho Chi Minh City, Vietnam)
XIAONIU XU (School of Forestry and Landscape Architecture, Anhui Agriculture University. No. 130, Changjiang West Road, Hefei, Anhui Province, China)
BUIMANH HUNG (Faculty of Forestry, Vietnam National University of Forestry. No. 1, Group 7, Tan Xuan, Xuan Mai Town, Chuong My District, Hanoi 100000, Vietnam)
LE VAN CUONG (Faculty of Forestry, Vietnam National University of Forestry. Dong Nai Campus, No. 98 Tran Phu, Trang Bom Town, Trang Bom District, Dong Nai 76000, Vietnam)
TRANTHI NGOAN (Faculty of Resource and Environmental Management, Vietnam National University of Forestry. Dong Nai Campus, No. 98 Tran Phu, Trang Bom Town, Trang Bom District, Dong Nai 76000, Vietnam)
THANHMINH NGUYEN (Faculty of Forestry, Vietnam National University of Forestry. No. 1, Group 7, Tan Xuan, Xuan Mai Town, Chuong My District, Hanoi 100000, Vietnam)

Biodiversitas Journal of Biological Diversity
Vol. 25 No. 2 (2024)

Abstract. Chau M, Quy N, Xu X, Hung B, Cuong LV, Ngoan T, Nguyen T. 2024. Variations in soil carbon, nitrogen, and phosphorus concentrations and stoichiometry with stand age in Acacia hybrid plantations in Southern Vietnam. Biodiversitas 25: 565-573. Soil Carbon (C), Nitrogen (N), and Phosphorus (P) contents are the three most critical soil nutrient elements required for plant growth and development, and their ecological stoichiometric ratios are significant indicators for understanding soil nutrient balance and cycling. This study was conducted to probe variations in the soil organic C (SC), total N (SN), and total P (SP) contents and stoichiometry at five soil depths (0-20, 20-40, 40-60, 60-80, and 80-100 cm) in Acacia hybrid plantations of five different ages (2-, 4-, 6-, 8-, and 10-year-old plantations) in Langa-Dongnai Forestry Company, Southern Vietnam. The results showed that forest age and soil depth substantially impacted soil nutrient contents and their stoichiometric characteristics. The concentrations of SC, SN, and SP as well as C/N, C/P, and N/P ratios increased as the forest stand age increased. The contents of SC, SN, and SP reduced with soil depth, indicating an obvious soil “surface-aggregation” phenomenon. The nutrient restriction varied based on forest stand development, shifting from restricted nitrogen in the earlier growth periods of trees to restricted phosphorus in the later growth periods. The findings demonstrate that to resolve the issue of restricted availability of these nutrient indexes, additional nitrogen should be supplied during earlier growth periods and additional phosphorus during later growth periods. The results further emphasize the importance of understanding SC, SN, and SP interactions and nutritional limitations and provide relevant theoretical support for sustainable Acacia hybrid plantation management in the Southern region.