Fry Ellen L, Wilkinson Anna, Johnson David, Pritchard William James, Ostle Nick J, Baggs Elizabeth M, Bardgett Richard D
Department of Earth and Environmental Sciences The University of Manchester Manchester UK.
Department of Biology Edge Hill University Lancashire UK.
Ecol Evol. 2021 Jul 27;11(17):11960-11973. doi: 10.1002/ece3.7963. eCollection 2021 Sep.
While the effect of drought on plant communities and their associated ecosystem functions is well studied, little research has considered how responses are modified by soil depth and depth heterogeneity. We conducted a mesocosm study comprising shallow and deep soils, and variable and uniform soil depths, and two levels of plant community composition, and exposed them to a simulated drought to test for interactive effects of these treatments on the resilience of carbon dioxide fluxes, plant functional traits, and soil chemical properties. We tested the hypotheses that: (a) shallow and variable depth soils lead to increased resistance and resilience of ecosystem functions to drought due to more exploitative plant trait strategies; (b) plant communities associated with intensively managed high fertility soils, will have more exploitative root traits than extensively managed, lower fertility plant communities. These traits will be associated with higher resistance and resilience to drought and may interact with soil depth and depth heterogeneity to amplify the effects on ecosystem functions. Our results showed that while there were strong soil depth/heterogeneity effects on plant-driven carbon fluxes, it did not affect resistance or resilience to drought, and there were no treatment effects on plant-available carbon or nitrogen. We did observe a significant increase in exploitative root traits in shallow and variable soils relative to deep and uniform, which may have resulted in a compensation effect which led to the similar drought responses. Plant community compositions representative of intensive management were more drought resilient than more diverse "extensive" communities irrespective of soil depth or soil depth heterogeneity. In intensively managed plant communities, root traits were more representative of exploitative strategies. Taken together, our results suggest that reorganization of root traits in response to soil depth could buffer drought effects on ecosystem functions.
虽然干旱对植物群落及其相关生态系统功能的影响已得到充分研究，但很少有研究考虑土壤深度和深度异质性如何改变这些响应。我们进行了一项中尺度实验研究，包括浅层和深层土壤、可变和均匀的土壤深度，以及两个植物群落组成水平，并将它们暴露于模拟干旱条件下，以测试这些处理对二氧化碳通量恢复力、植物功能性状和土壤化学性质的交互作用。我们检验了以下假设：(a) 浅层和可变深度土壤由于植物更多的开拓性性状策略，导致生态系统功能对干旱的抵抗力和恢复力增加；(b) 与集约化管理的高肥力土壤相关的植物群落，将比粗放管理、低肥力的植物群落具有更多的开拓性根系性状。这些性状将与更高的抗旱性和恢复力相关，并可能与土壤深度和深度异质性相互作用，放大对生态系统功能的影响。我们的结果表明，虽然土壤深度/异质性对植物驱动的碳通量有强烈影响，但它并不影响对干旱的抵抗力或恢复力，并且对植物可利用的碳或氮没有处理效应。我们确实观察到，相对于深层和均匀土壤，浅层和可变土壤中开拓性根系性状显著增加，这可能导致了一种补偿效应，从而产生了相似的干旱响应。无论土壤深度或土壤深度异质性如何，代表集约化管理的植物群落组成比更多样化的“粗放”群落更具抗旱恢复力。在集约化管理的植物群落中，根系性状更能代表开拓性策略。综上所述，我们的结果表明，根系性状响应土壤深度的重新组织可以缓冲干旱对生态系统功能的影响。
