TY - JOUR

T1 - Radiocarbon evidence of the impact of forest-to-plantation conversion on soil organic carbon dynamics on a tropical island

AU - Jiang, Y.

AU - Luo, C.

AU - Zhang, D.

AU - Ostle, N.J.

AU - Cheng, Z.

AU - Ding, P.

AU - Shen, C.

AU - Zhang, G.

PY - 2020/10/1

Y1 - 2020/10/1

N2 - Tropical soils are critical terrestrial carbon reservoirs with abundant biodiversity that respond rapidly to environmental change. Globally, the expanding conversion of natural tropical forest to plantations in recent decades, to meet economic demands, has markedly influenced the cycling of soil organic carbon (SOC) pools; however, the mechanisms underlying the changes in SOC dynamics are poorly understood. In this study, we examined the SOC dynamics and soil microbial communities at five adjacent tropical forest sites characterized by different logging and plantation practices over the past few decades on Hainan Island, China, by applying natural abundance radiocarbon ( 14C) and phospholipid fatty acid (PLFA) analysis. At a >35-year rubber plantation site and a >50-year eucalyptus plantation site, an abnormal up-profile decrease in radiocarbon abundance was observed in the upper 30 cm soil layer. This could be indicative of continued soil organic matter decomposition long after forest–plantation conversion, and was consistent with the SOC inventories in the upper 30 cm soil layer at the two sites being significantly lower than those of NF. Both the SOC apparent radiocarbon ages and SOC inventory at a eucalyptus plantation site in which tillage was stopped 20 years ago were similar to those of NF, indicating that a recovery process had occurred. The soil microbial biomass was generally lower at the plantation sites than at the NF site. Both the radiocarbon abundance and SOC inventories in the upper 30 cm soil layer showed positive correlations with the soil microbial biomass, suggesting that microbes may have played a key role in the fate of SOC. This study provided evidence that forest–plantation conversion may facilitate the dissimilation of SOC, and also demonstrated that radiocarbon can serve as a powerful tool for assessing the potential changes of soil carbon dynamics resulting from forest-to-plantation conversion.

AB - Tropical soils are critical terrestrial carbon reservoirs with abundant biodiversity that respond rapidly to environmental change. Globally, the expanding conversion of natural tropical forest to plantations in recent decades, to meet economic demands, has markedly influenced the cycling of soil organic carbon (SOC) pools; however, the mechanisms underlying the changes in SOC dynamics are poorly understood. In this study, we examined the SOC dynamics and soil microbial communities at five adjacent tropical forest sites characterized by different logging and plantation practices over the past few decades on Hainan Island, China, by applying natural abundance radiocarbon ( 14C) and phospholipid fatty acid (PLFA) analysis. At a >35-year rubber plantation site and a >50-year eucalyptus plantation site, an abnormal up-profile decrease in radiocarbon abundance was observed in the upper 30 cm soil layer. This could be indicative of continued soil organic matter decomposition long after forest–plantation conversion, and was consistent with the SOC inventories in the upper 30 cm soil layer at the two sites being significantly lower than those of NF. Both the SOC apparent radiocarbon ages and SOC inventory at a eucalyptus plantation site in which tillage was stopped 20 years ago were similar to those of NF, indicating that a recovery process had occurred. The soil microbial biomass was generally lower at the plantation sites than at the NF site. Both the radiocarbon abundance and SOC inventories in the upper 30 cm soil layer showed positive correlations with the soil microbial biomass, suggesting that microbes may have played a key role in the fate of SOC. This study provided evidence that forest–plantation conversion may facilitate the dissimilation of SOC, and also demonstrated that radiocarbon can serve as a powerful tool for assessing the potential changes of soil carbon dynamics resulting from forest-to-plantation conversion.

KW - Forest-to-plantation conversion

KW - Microbial communities

KW - Radiocarbon analysis

KW - Soil organic carbon dynamics

KW - Biodiversity

KW - Dynamics

KW - Fatty acids

KW - Forestry

KW - Microorganisms

KW - Organic carbon

KW - Phospholipids

KW - Rubber plantations

KW - Tropics

KW - Environmental change

KW - Eucalyptus plantations

KW - Phospholipid fatty acid analysis

KW - Positive correlations

KW - Soil carbon dynamics

KW - Soil microbial biomass

KW - Soil microbial community

KW - Soil organic matters

KW - Soils

KW - abundance

KW - decomposition

KW - microbial activity

KW - microbial community

KW - phospholipid

KW - plantation forestry

KW - soil carbon

KW - soil microorganism

KW - soil organic matter

KW - tropical forest

KW - Hainan

KW - Eucalyptus

U2 - 10.1016/j.geoderma.2020.114484

DO - 10.1016/j.geoderma.2020.114484

M3 - Journal article

VL - 375

JO - Geoderma

JF - Geoderma

SN - 0016-7061

M1 - 114484

ER -