Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems/CAS Engineering Laboratory for Vegetation Ecosystem Restoration on Islands and Coastal Zones, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China; Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Guangzhou 510650, China; South China National Botanical Garden, Guangzhou 510650, China.
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2023 Jul 10;881:163204. doi: 10.1016/j.scitotenv.2023.163204. Epub 2023 Apr 10.
Tropical primary forests are being destroyed at an alarming rate and converted for other land uses which is expected to greatly influence soil carbon (C) cycling. However, our understanding of how tropical forest conversions affect the accumulation of compounds in soil functional C pools remains unclear. Here, we collected soils from primary forests (PF), secondary forests (SF), oil-palm (OP), and rubber plantations (RP), and assessed the accumulation of plant- and microbial-derived compounds within soil organic carbon (SOC), particulate (POC) and mineral-associated (MAOC) organic C. PF conversion to RP greatly decreased SOC, POC, and MAOC concentrations, whereas conversion to SF increased POC concentrations and decreased MAOC concentrations, and conversion to OP only increased POC concentrations. PF conversion to RP decreased lignin concentrations and increased amino sugar concentrations in SOC pools which increased the stability of SOC, whereas conversion to SF only increased the lignin concentrations in POC, and conversion to OP just increased lignin concentrations in POC and decreased it in MAOC. We observed divergent dynamics of amino sugars (decrease) and lignin (increase) in SOC with increasing SOC. Only lignin concentrations increased in POC with increasing POC and amino sugars concentrations decreased in MAOC with increasing MAOC. Conversion to RP significantly decreased soil enzyme activities and microbial biomasses. Lignin accumulation was associated with microbial properties, whereas amino sugar accumulation was mainly associated with soil nutrients and stoichiometries. These results suggest that the divergent accumulation of plant- and microbial-derived C in SOC was delivered by the distribution and original composition of functional C pools under forest conversions. Forest conversions changed the formation and stabilization processes of SOC in the long run which was associated with converted plantations and management. The important roles of soil nutrients and stoichiometry also provide a natural-based solution to enhance SOC sequestration via nutrient management in tropical forests.
热带原始森林正以惊人的速度被破坏，并被转化为其他土地用途，这预计将极大地影响土壤碳（C）循环。然而，我们对于热带森林转化如何影响土壤功能 C 库中化合物的积累仍不清楚。在这里，我们从原始森林（PF）、次生林（SF）、油棕（OP）和橡胶种植园（RP）收集土壤，并评估了植物和微生物衍生化合物在土壤有机碳（SOC）、颗粒（POC）和矿物结合（MAOC）有机 C 中的积累。PF 向 RP 的转化大大降低了 SOC、POC 和 MAOC 的浓度，而向 SF 的转化增加了 POC 的浓度，降低了 MAOC 的浓度，向 OP 的转化仅增加了 POC 的浓度。PF 向 RP 的转化降低了 SOC 库中木质素的浓度，增加了氨基糖的浓度，从而提高了 SOC 的稳定性，而向 SF 的转化仅增加了 POC 中的木质素浓度，向 OP 的转化仅增加了 POC 中的木质素浓度，降低了 MAOC 中的木质素浓度。我们观察到随着 SOC 的增加，SOC 中氨基糖（减少）和木质素（增加）的动态存在分歧。只有 POC 中的木质素浓度随着 POC 的增加而增加，MAOC 中的氨基糖浓度随着 MAOC 的增加而减少。向 RP 的转化显著降低了土壤酶活性和微生物生物量。木质素的积累与微生物特性有关，而氨基糖的积累主要与土壤养分和化学计量有关。这些结果表明，SOC 中植物和微生物衍生 C 的不同积累是由森林转化下功能 C 库的分布和原始组成决定的。从长远来看，森林转化改变了 SOC 的形成和稳定过程，这与转化后的种植园和管理有关。土壤养分和化学计量的重要作用也为通过热带森林的养分管理来增强 SOC 固存提供了一种基于自然的解决方案。
