Molecular Phytopathology and Mycotoxin Research, Faculty of Agricultural Sciences, University of Goettingen, Goettingen, Germany.
Soil Science of Tropical and Subtropical Ecosystems, Faculty of Forest Sciences and Forest Ecology, University of Goettingen, Goettingen, Germany.
PLoS One. 2019 Jun 27;14(6):e0218779. doi: 10.1371/journal.pone.0218779. eCollection 2019.
Integration of trees in agroforestry systems can increase the system sustainability compared to monocultures. The resulting increase in system complexity is likely to affect soil-N cycling by altering soil microbial community structure and functions. Our study aimed to assess the abundance of genes encoding enzymes involved in soil-N cycling in paired monoculture and agroforestry cropland in a Phaeozem soil, and paired open grassland and agroforestry grassland in Histosol and Anthrosol soils. The soil fungi-to-bacteria ratio was greater in the tree row than in the crop or grass rows of the monoculture cropland and open grassland in all soil types, possibly due to increased input of tree residues and the absence of tillage in the Phaeozem (cropland) soil. In the Phaeozem (cropland) soil, gene abundances of amoA indicated a niche differentiation between archaeal and bacterial ammonia oxidizers that distinctly separated the influence of the tree row from the crop row and monoculture system. Abundances of nitrate (napA and narG), nitrite (nirK and nirS) and nitrous oxide reductase genes (nosZ clade I) were largely influenced by soil type rather than management system. The soil types' effects were associated with their differences in soil organic C, total N and pH. Our findings show that in temperate regions, conversion of monoculture cropland and open grassland to agroforestry systems can alter the abundance of soil bacteria and fungi and soil-N-cycling genes, particularly genes involved in ammonium oxidation.
与单一栽培相比，农林复合系统中树木的融入可以提高系统的可持续性。系统复杂性的增加可能通过改变土壤微生物群落结构和功能来影响土壤氮循环。我们的研究旨在评估在黑钙土、腐殖土和人为土中，与单一栽培的作物和草地行成对比的，配对的农林复合作物和草地中行的土壤氮循环相关酶编码基因的丰度。在所有土壤类型中，树木行的土壤真菌与细菌的比例大于单一栽培作物和草地中行的比例，可能是由于黑钙土（农田）中树木残体输入增加和免耕的存在。在黑钙土（农田）中，amoA 基因的丰度表明古菌和细菌氨氧化菌之间存在生态位分化，这种分化明显将树木行的影响与作物行和单一栽培系统的影响区分开来。硝酸盐（napA 和 narG）、亚硝酸盐（nirK 和 nirS）和氧化亚氮还原酶基因（nosZ Ⅰ类）的丰度主要受土壤类型而不是管理系统的影响。土壤类型的影响与土壤有机碳、总氮和 pH 值的差异有关。我们的研究结果表明，在温带地区，将单一栽培农田和开阔草地转化为农林复合系统可以改变土壤细菌和真菌以及土壤氮循环基因的丰度，特别是与氨氧化有关的基因。
