Experimental evidence for drought induced alternative stable states of soil moisture.
Experimental evidence for drought induced alternative stable states of soil moisture.
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DOI：
10.1038/srep20018
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发表时间：
2016-01-25
影响因子：
4.6
通讯作者：
Emmett BA
中科院分区：
文献类型：
--
作者：
Robinson DA;Jones SB;Lebron I;Reinsch S;Domínguez MT;Smith AR;Jones DL;Marshall MR;Emmett BA
生态系统可能表现出替代稳定状态（ASS），以响应环境变化。模型和观测数据广泛支持ASS理论，但支持这一理论的操纵实验证据有限。在这里，我们提供了长期的操作和观测数据支持干旱诱导的替代稳定的土壤水分状态（不可逆的土壤湿润）在高地大西洋石楠，主要是Calluna vulgaris（L.）船体。人为重复中度夏季干旱，强烈的自然夏季干旱都降低了恢复力，导致土壤水分动态的变化。夏季反复中度干旱使冬季土壤持水量下降约10%。然而，强烈的夏季干旱，叠加在实验中，在2003年开始，并在2005年达到顶峰，造成了意想不到的侵蚀的恢复力和转向一个ASS;无论是实验干旱操纵和控制地块，损害土壤在冬季复湿。测量地块外，植被清除，没有证据表明水分转移。进一步的独立证据支持我们的研究结果，从历史上的土壤水分监测在一个长期的高地水文观测站。这些结果预示着我们需要一个新的范式来理解土壤结构，水力学和气候相互作用。
Ecosystems may exhibit alternative stable states (ASS) in response to environmental change. Modelling and observational data broadly support the theory of ASS, however evidence from manipulation experiments supporting this theory is limited. Here, we provide long-term manipulation and observation data supporting the existence of drought induced alternative stable soil moisture states (irreversible soil wetting) in upland Atlantic heath, dominated by Calluna vulgaris (L.) Hull. Manipulated repeated moderate summer drought, and intense natural summer drought both lowered resilience resulting in shifts in soil moisture dynamics. The repeated moderate summer drought decreased winter soil moisture retention by ~10%. However, intense summer drought, superimposed on the experiment, that began in 2003 and peaked in 2005 caused an unexpected erosion of resilience and a shift to an ASS; both for the experimental drought manipulation and control plots, impairing the soil from rewetting in winter. Measurements outside plots, with vegetation removal, showed no evidence of moisture shifts. Further independent evidence supports our findings from historical soil moisture monitoring at a long-term upland hydrological observatory. The results herald the need for a new paradigm regarding our understanding of soil structure, hydraulics and climate interaction.