Mineral-associated organic carbon predicts the variations in microbial biomass and specific enzyme activities in a subtropical forest
Mineral-associated organic carbon predicts the variations in microbial biomass and specific enzyme activities in a subtropical forest
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DOI：
10.1016/j.geoderma.2023.116671
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发表时间：
2023-11
期刊：
影响因子：
6.1
通讯作者：
Rong Chen;Liming Yin;Xiaohong Wang;T. Chen;Linqiao Jia;Qi Jiang;Maokui Lyu;Xiaodong Yao;Guangshui Chen
中科院分区：
文献类型：
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作者：
Rong Chen;Liming Yin;Xiaohong Wang;T. Chen;Linqiao Jia;Qi Jiang;Maokui Lyu;Xiaodong Yao;Guangshui Chen
热带和亚热带森林在全球碳预算中至关重要。尽管将土壤有机碳(SOC)分离为颗粒有机碳(POC)和矿物伴生有机碳(MAOC)提高了我们对SOC固存的理解，但热带和亚热带森林中SOC及其组分(POC和MAOC)如何与土壤微生物特性相互作用仍不清楚，这对改进土壤C预测是至关重要的。在这里，我们对湿润亚热带森林中种植不同树种的6个林分下的土壤进行采样，以评估微生物特征(生物量和特定酶活性)与有机碳及其组分之间的相互作用。研究发现，矿物伴生有机碳(MAOC)占土壤有机碳的78-86%，且与有机碳的共变性很强，是最大的资源库。微生物(尤其是细菌)生物量和比酶活性与土壤有机碳(尤其是MAOC)之间存在着显著的相关性。线性混合模型的结果表明，SOC，尤其是MAOC能显著预测微生物(尤其是细菌)生物量和比酶活性的变化。然而，微生物特性未能预测SOC的变化，特别是MAOC。微生物生物量与碳氮酶活性之间存在显著的负相关关系，当控制SOC或MAOC时，这种关系消失，但当控制颗粒有机碳(POC)时，这种关系消失，这表明微生物投资在生物量增长和资源获取之间存在权衡，这种权衡是由SOC，特别是MAOC控制的。总体而言，我们的发现为微生物性状与土壤C组分之间的相互作用提供了强有力的证据，从而突出了MAOC在调节微生物生物量、特定酶活性及其权衡方面的关键作用，而微生物生物量和特定酶活性可能不是亚热带森林MAOC的重要决定因素。
Tropical and subtropical forests are critical in global carbon budgets. Although separating soil organic carbon (SOC) into particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) advances our understanding of SOC sequestration, how SOC and its fractions (POC and MAOC) interact with soil microbial traits in tropical and subtropical forests remains unclear, which is critical for improving soil C projections. Here we sampled soils beneath six stands planted with different tree species in a humid subtropical forest to assess the interactions between microbial traits (biomass and specific enzyme activities) and SOC and its fractions. We found that mineral-associated organic carbon (MAOC) accounted for 78–86% of SOC and co-varied strongly with SOC, representing the largest resource pool. There were significant relationships between microbial (especially bacteria) biomass and specific enzyme activities and SOC (especially MAOC). The results of linear mixed models indicated that SOC and particularly MAOC could significantly predict the variations in microbial (especially bacteria) biomass and specific enzyme activities. However, microbial traits failed in predicting the variation in SOC and particularly the MAOC. There were significant negative relationships between microbial biomass and specific C- and N-acquisition enzyme activities and these relationships disappeared when controlling SOC or MAOC but not when controlling particulate organic carbon (POC), suggesting that there is a tradeoff of microbial investment between biomass growth and resource acquisition, and this tradeoff is controlled by SOC, particularly the MAOC. Overall, our findings provide strong evidence for the interactions between microbial traits and soil C fractions and thus highlight that MAOC plays a critical role in regulating microbial biomass, specific enzyme activities, and their tradeoff, whereas microbial biomass and specific enzyme activity may not be important determinants of MAOC in subtropical forests.