CREAF, Cerdanyola del Vallès, 08193, Catalonia, Spain; CSIC, Global Ecology Unit CREAF-CSIC-UAB, Bellaterra 08193, Catalonia, Spain.
Department of Biosciences, University Salzburg, Hellbrunnerstraße 34, 5020 Salzburg, Austria.
Sci Total Environ. 2020 Sep 15;735:139554. doi: 10.1016/j.scitotenv.2020.139554. Epub 2020 May 20.
The drivers of global change, such as increasing drought and nutrient deposition, are affecting soils and their microbial communities in many different habitats, but how these factors interact remains unclear. Quercus ilex and Pinus sylvestris are two important tree species in Mediterranean montane areas that respond differently to drought, which may be associated with the soils in which they grow. We measured soil respiration and physiologically profiled microbial communities to test the impact of drought and subsequent recovery on soil function and diversity for these two species. We also tested whether the addition of nitrogen and phosphorus modified these effects. Drought was the stronger driver of changes to the soil communities, decreasing diversity (Shannon index), and evenness for both species and decreasing soil respiration for Q. ilex when N was added. Soil respiration for P. sylvestris during the drought period was positively affected by N addition but was not affected by water stress. P addition during the drought period did not affect soil respiration for either tree species but did interact with soil-water content to affect community evenness for P. sylvestris. The two species also differed following the recovery from drought. Soil respiration for Q. ilex recovered fully after the drought treatment ended but decreased for P. sylvestris, whereas the soil community was more resilient for P. sylvestris than Q. ilex. Nutrient addition did not affect respiration or community composition or diversity during the recovery period. Soil respiration was generally weakly positively correlated with soil diversity. We demonstrate that short-term water stress and nutrient addition can have variable effects on the soil communities associated with different tree species and that the compositions of the communities can become uncoupled from soil respiration. Overall, we show that drought may be a stronger driver of changes to soil communities than nitrogen or phosphorus deposition.
全球变化的驱动因素，如干旱加剧和养分沉积，正在许多不同的生境中影响土壤及其微生物群落，但这些因素如何相互作用尚不清楚。欧洲栓皮栎和欧洲赤松是地中海山区的两种重要树种，它们对干旱的反应不同，这可能与它们生长的土壤有关。我们测量了土壤呼吸和生理特征化微生物群落，以测试干旱及其后的恢复对这两个物种的土壤功能和多样性的影响。我们还测试了氮和磷的添加是否会改变这些影响。干旱是导致土壤群落变化的更强驱动因素，降低了两个物种的多样性（香农指数）和均匀度，并且在添加氮时还降低了欧洲栓皮栎的土壤呼吸。在干旱期间，氮的添加对欧洲赤松的土壤呼吸有积极影响，但不受水分胁迫的影响。在干旱期间添加磷对两种树种的土壤呼吸均无影响，但与土壤水分含量相互作用，影响欧洲赤松的群落均匀度。两种树种在从干旱中恢复后也表现出不同。在干旱处理结束后，欧洲栓皮栎的土壤呼吸完全恢复，但欧洲赤松的土壤呼吸下降，而欧洲赤松的土壤群落比欧洲栓皮栎更具弹性。养分添加在恢复期间对呼吸或群落组成或多样性均无影响。土壤呼吸与土壤多样性呈弱正相关。我们证明，短期水分胁迫和养分添加对不同树种相关的土壤群落有不同的影响，而且群落的组成可以与土壤呼吸脱钩。总的来说，我们表明，干旱可能是土壤群落变化的更强驱动因素，而不是氮或磷沉积。
