Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
Georgia Institute of Technology, School of Civil and Environmental Engineering, Atlanta, GA, 30332, USA.
Sci Rep. 2018 Feb 16;8(1):3142. doi: 10.1038/s41598-018-21197-0.
Forest ecosystems are critical to global biogeochemical cycles but under pressure from harvesting and climate change. We investigated the effects of organic matter (OM) removal during forest harvesting on the genetic potential of soil communities for biomass decomposition and nitrogen cycling in five ecozones across North America. We analyzed 107 samples, representing four treatments with varied levels of OM removal, at Long-Term Soil Productivity Study sites. Samples were collected more than ten years after harvesting and replanting and were analyzed via shotgun metagenomics. High-quality short reads totaling 1.2 Tbp were compared to the Carbohydrate Active Enzyme (CAZy) database and a custom database of nitrogen cycle genes. Gene profile variation was mostly explained by ecozone and soil layer. Eleven CAZy and nine nitrogen cycle gene families were associated with particular soil layers across all ecozones. Treatment effects on gene profiles were mainly due to harvesting, and only rarely to the extent of OM removal. Harvesting generally decreased the relative abundance of CAZy genes while increasing that of nitrogen cycle genes, although these effects varied among ecozones. Our results suggest that ecozone-specific nutrient availability modulates the sensitivity of the carbon and nitrogen cycles to harvesting with possible consequences for long-term forest sustainability.
森林生态系统对全球生物地球化学循环至关重要，但它们正承受着采伐和气候变化的压力。我们研究了森林采伐过程中有机质（OM）去除对土壤微生物群落生物量分解和氮循环遗传潜力的影响，该研究横跨北美五个生态区。我们在长期土壤生产力研究点分析了 107 个样本，这些样本代表了四种不同有机质去除水平的处理。在采伐和重新造林 10 多年后采集了这些样本，并通过 shotgun 宏基因组学进行了分析。高质量的短读总长 1.2 Tbp，与碳水化合物活性酶（CAZy）数据库和氮循环基因的自定义数据库进行了比较。基因谱的变化主要由生态区和土壤层解释。在所有生态区中，11 个 CAZy 和 9 个氮循环基因家族与特定的土壤层有关。基因谱受处理的影响主要是由于采伐，而很少是由于有机质去除的程度。一般来说，采伐会降低 CAZy 基因的相对丰度，而增加氮循环基因的相对丰度，尽管这些影响在生态区之间有所不同。我们的研究结果表明，特定生态区的养分供应情况调节了碳氮循环对采伐的敏感性，这可能对森林的长期可持续性产生影响。
