School of Geographical Science, Fujian Normal University, Fuzhou 350007, China; Key Laboratory of Humid Subtropical Eco-geographical Process of Ministry of Education, Fujian Provincial Key Laboratory for Plant Eco-physiology, Fujian Normal University, Fuzhou 350117, China; Institute of Geography, Fujian Normal University, Fuzhou 350007, China.
Institute of Agriculture and Life Sciences, Gyeongsang National University, Jinju 52828, South Korea.
Sci Total Environ. 2024 Jul 15;934:173158. doi: 10.1016/j.scitotenv.2024.173158. Epub 2024 May 11.
Soil respiration (R) is a major component of the global carbon (C) cycle and is influenced by the availability of nutrients such as phosphorus (P). However, the response of R to P addition in P-limited subtropical forest ecosystems and the underlying mechanisms remain poorly understood. To address this, we conducted a P addition experiment (50 kg P ha yr) in a subtropical Chinese fir (Cunninghamia lanceolata) plantation forest. We separated R into heterotrophic respiration (R), root respiration (R), and mycorrhizal hyphal respiration (R), and quantified soil properties, microbial biomass (phospholipid fatty acid, PLFA), fungal community composition (ITS), and the activity of extracellular enzymes. Phosphorus addition significantly increased R and R, but decreased R and did not influence R. Further, P addition increased fungal, bacterial, and total PLFAs, and phenol oxidase activity. Conversely, P application decreased root biomass and did not alter the relative abundance of symbiotrophic fungi. Phosphorus enrichment therefore enhances soil C emissions by promoting organic matter decomposition by heterotrophic activity, rather than via increases in root or mycorrhizal respiration. This advances our mechanistic understanding of the relationship between fertility and soil respiration in subtropical forests, with implications for predicting soil C emissions under global change.
土壤呼吸（R）是全球碳（C）循环的主要组成部分，受到磷（P）等养分供应的影响。然而，在磷限制的亚热带森林生态系统中，R 对 P 添加的响应及其潜在机制仍知之甚少。为了解决这个问题，我们在亚热带杉木（Cunninghamia lanceolata）人工林进行了 P 添加实验（50 kg P ha yr）。我们将 R 分为异养呼吸（R）、根系呼吸（R）和菌根菌丝呼吸（R），并量化了土壤性质、微生物生物量（磷脂脂肪酸，PLFA）、真菌群落组成（ITS）和胞外酶活性。P 添加显著增加了 R 和 R，但降低了 R，而 R 没有受到影响。此外，P 添加增加了真菌、细菌和总 PLFA 以及多酚氧化酶活性。相反，P 应用减少了根生物量，而没有改变共生真菌的相对丰度。因此，磷富集通过促进异养活性分解有机物质来增强土壤 C 排放，而不是通过增加根系或菌根呼吸来实现。这推进了我们对亚热带森林肥力与土壤呼吸关系的机制理解，对预测全球变化下的土壤 C 排放具有重要意义。
