School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, 1010, New Zealand.
Plant Health & Environment Laboratory, Ministry for Primary Industries, PO Box 2095, Auckland, 1140, New Zealand.
Environ Microbiol. 2021 Jun;23(6):2919-2936. doi: 10.1111/1462-2920.15473. Epub 2021 May 6.
Forest-to-pasture conversion is known to cause global losses in plant and animal diversity, yet impacts of livestock management after such conversion on vital microbial communities in adjoining natural ecosystems remain poorly understood. We examined how pastoral land management practices impact soil microorganisms in adjacent native forest fragments, by comparing bacterial communities sampled along 21 transects bisecting pasture-forest boundaries. Our results revealed greater bacterial taxon richness in grazed pasture soils and the reduced dispersal of pasture-associated taxa into adjacent forest soils when land uses were separated by a boundary fence. Relative abundance distributions of forest-associated taxa (i.e., Proteobacteria and Nitrospirae) and a pasture-associated taxon (i.e., Firmicutes) also suggest a greater impact of pastoral land uses on forest fragment soil bacterial communities when no fence is present. Bacterial community richness and composition were most related to changes in soil physicochemical variables commonly associated with agricultural fertilization, including concentrations of Olsen P, total P, total Cd, delta N and the ratio of C:P and N:P. Overall, our findings demonstrate clear, and potentially detrimental effects of agricultural disturbance on bacterial communities in forest soils adjacent to pastoral land. We provide evidence that simple land management decisions, such as livestock exclusion, can mitigate the effects of agriculture on adjacent soil microbial communities.
森林转化为牧场已知会导致全球植物和动物多样性的丧失，但这种转变后对毗邻自然生态系统中重要微生物群落的牲畜管理的影响仍知之甚少。我们通过比较沿 21 条穿过牧场-森林边界的样带采集的细菌群落，研究了牧场管理实践如何影响相邻原生林片段中的土壤微生物。我们的结果表明，在放牧牧场土壤中，细菌分类群丰富度更高，当土地用途由边界围栏隔开时，与牧场相关的分类群向相邻森林土壤的扩散减少。与森林相关的分类群（即变形菌门和硝化螺旋菌门）和与牧场相关的分类群（即厚壁菌门）的相对丰度分布也表明，当不存在围栏时，牧场土地利用对无围栏森林片段土壤细菌群落的影响更大。细菌群落丰富度和组成与土壤理化变量的变化最相关，这些变量通常与农业施肥有关，包括奥尔森磷、总磷、总镉、δN 和 C:P 比以及 N:P 比。总的来说，我们的研究结果表明，农业干扰对毗邻牧场的森林土壤中的细菌群落具有明显的、潜在的有害影响。我们提供的证据表明，简单的土地管理决策，如牲畜排除，可以减轻农业对相邻土壤微生物群落的影响。
