State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, 150081, P R China.
School of Geography and Ocean Science, Nanjing University, Nanjing, 210023, P R China.
ISME J. 2023 Nov;17(11):1872-1883. doi: 10.1038/s41396-023-01496-9. Epub 2023 Aug 22.
The microbiome function responses to land use change are important for the long-term prediction and management of soil ecological functions under human influence. However, it has remains uncertain how the biogeographic patterns of soil functional composition change when transitioning from natural steppe soils (NS) to agricultural soils (AS). We collected soil samples from adjacent pairs of AS and NS across 900 km of Mollisol areas in northeast China, and the soil functional composition was characterized using shotgun sequencing. AS had higher functional alpha-diversity indices with respect to KO trait richness and a higher Shannon index than NS. The distance-decay slopes of functional gene composition were steeper in AS than in NS along both spatial and environmental gradients. Land-use conversion from steppe to farmland diversified functional gene profiles both locally and spatially; it increased the abundances of functional genes related to labile carbon, but decreased those related to recalcitrant substrate mobilization (e.g., lignin), P cycling, and S cycling. The composition of gene functional traits was strongly driven by stochastic processes, while the degree of stochasticity was higher in NS than in AS, as revealed by the neutral community model and normalized stochasticity ratio analysis. Alpha-diversity of core functional genes was strongly related to multi-nutrient cycling in AS, suggesting a key relationship to soil fertility. The results of this study challenge the paradigm that the conversion of natural to agricultural habitat will homogenize soil properties and biology while reducing local and regional gene functional diversity.
土壤微生物功能对土地利用变化的响应对于人类影响下土壤生态功能的长期预测和管理非常重要。然而，当从自然草原土壤（NS）向农业土壤（AS）过渡时，土壤功能组成的生物地理格局如何变化仍然不确定。我们从中国东北 900 公里的黑土地区采集了相邻的 AS 和 NS 的土壤样本，并使用 shotgun 测序对土壤功能组成进行了表征。AS 的 KO 特征丰富度和 Shannon 指数的功能 alpha 多样性指数较高。在空间和环境梯度上，AS 的功能基因组成的距离衰减斜率比 NS 更陡峭。从草原到农田的土地利用转换使功能基因图谱在局部和空间上多样化；它增加了与不稳定碳有关的功能基因的丰度，但降低了与难移动基质（如木质素）、P 循环和 S 循环有关的功能基因的丰度。基因功能性状的组成受随机过程强烈驱动，而在 NS 中，随机过程的程度高于 AS，这是由中性群落模型和归一化随机性比分析揭示的。AS 中核心功能基因的 alpha 多样性与多种养分循环密切相关，这表明与土壤肥力有重要关系。本研究的结果挑战了这样一种观点，即自然生境向农业生境的转变将使土壤特性和生物学同质化，同时降低局部和区域的基因功能多样性。
