CEBAS-CSIC, Department of Soil and Water Conservation, Campus Universitario de Espinardo, 30100 Murcia, Spain.
Laboratory of Environmental Microbiology, Institute of Microbiology of the CAS, Vídeňská 1083, Praha 4 14220, Czech Republic.
Sci Total Environ. 2019 Apr 20;662:276-286. doi: 10.1016/j.scitotenv.2019.01.233. Epub 2019 Jan 22.
The growth and survival of plants in semiarid Mediterranean forests can be improved through the benefits conferred by thinning, a forest management practice that removes trees and reduces the competition between the remaining ones. Here, we evaluate the impacts of induced drought (the exclusion of 25% of the natural rainfall for 5 years) and thinning, and their interaction, with the objective of determining whether the thinning of Holm oak (Quercus ilex L.) modulates the resistance of the soil microbial community to drought. Sequencing of 16S rRNA and ITS amplicons revealed that drought, thinning, and their interaction influenced the composition of the bacterial community, while the fungal community was exclusively affected by thinning. Thinning consisted of the removal of the aboveground parts of the Holm oak trees, which were thereafter left in forest stand. Thinning contributed to the C and N contents, with parallel increases in microbial biomass, particularly in summer. Drought increased the amounts of total organic C and total N, likely due to the reduced enzyme activities. Indeed, the composition of the bacterial community was modulated primarily by the indirect and long-term effects of drought - the accumulation of soil organic matter - rather than by the direct effect of the lower water content imposed by the drought treatments. Thinning under drought conditions did not increase soil organic C (SOC) content. However, the resistance of the soil microbial community to drought was fostered by thinning, particularly at the functional level, as indicated by the enzyme activities related to C, N and P cycles. These responses were associated to variations in the composition of the microbial communities in thinned, drought-exposed plots, in comparison to unthinned, drought-exposed plots. In conclusion, the interaction between forest management and drought influenced the soil microbial community of a Holm oak-dominated Mediterranean ecosystem.
在半干旱地中海森林中，通过疏伐（移除树木并减少剩余树木之间的竞争）等森林管理措施，可以提高植物的生长和生存能力。在这里，我们评估了诱发干旱（将自然降雨量减少 25%，持续 5 年）和疏伐及其相互作用对土壤微生物群落抗旱能力的影响，目的是确定是否疏伐欧洲栓皮栎（Quercus ilex L.）可以调节土壤微生物群落的抗旱能力。16S rRNA 和 ITS 扩增子测序表明，干旱、疏伐及其相互作用影响了细菌群落的组成，而真菌群落仅受疏伐的影响。疏伐包括去除欧洲栓皮栎的地上部分，然后将其留在林分中。疏伐有助于 C 和 N 含量的增加，同时微生物生物量也相应增加，尤其是在夏季。干旱增加了总有机碳和总氮的含量，这可能是由于酶活性降低所致。事实上，细菌群落的组成主要是通过干旱的间接和长期影响（土壤有机质的积累）来调节，而不是通过干旱处理导致的较低含水量的直接影响。在干旱条件下疏伐并没有增加土壤有机碳（SOC）含量。然而，在干旱条件下疏伐促进了土壤微生物群落对干旱的抵抗力，特别是在功能水平上，这反映在与 C、N 和 P 循环相关的酶活性上。与未疏伐、干旱暴露的样地相比，在疏伐、干旱暴露的样地中，这些响应与微生物群落组成的变化有关。总之，森林管理和干旱之间的相互作用影响了以欧洲栓皮栎为主导的地中海生态系统的土壤微生物群落。
