Abstract
The current state of an ecosystem results from the complex interaction of abiotic and biotic drivers jointly influenced by their dynamics and the legacy of a systems' history. Negative synergies between emerging climatically extreme events and past environmental impacts are expected to shift ecological communities to alternative stable states or towards hysteretic successional trajectories. However, knowledge on mutual effects of environmental stressors is scarce especially for not experimentally controlled, natural ecosystems.We investigated the effect of a prolonged drought and heat wave occurred during 2003 on the short‐term vegetation responses of forest springs, a waterlogged type of ecosystem which is highly abundant in Central European siliceous mountains. These landscapes experienced strong impairment by 20th century atmospheric acidification. For different levels of acidification, we investigated plant community composition and water chemistry of 57 springs before (1996) during (2003) and after (2004–2006) the summer of 2003 and quantified ecological resilience and elasticity related to this extreme event for single plant species and species assemblages of whole communities.The extreme dry and hot summer 2003 significantly decreased discharge, increased water temperature and affected water chemistry of the investigated springs. Ecological resilience and elasticity against the climatic extreme event differed significantly between communities dependent on their previous impact by acidification. Springs which were less affected by acidification performed higher resilience and elasticity than strongly acidified springs.Our study shows that strong negative synergies between emerging climatic extreme events and past environmental impairments occur on landscape scale. Hitherto, such interactions between climate change, hydrochemistry, and the responses of ecosystems have been neglected.
Highlights
A multitude of abiotic and biotic non-linear dynamics and interactions modified by historical events qualify ecosystems to be complex adaptive systems (Gell-Mann 1994, Levin 1998, Norberg 2004)
For different levels of acidification, we investigated plant community composition and water chemistry of 57 springs before (1996) during (2003) and after (2004–2006) the summer of 2003 and quantified ecological resilience and elasticity related to this extreme event for single plant species and species assemblages of whole communities
Complexity is inherent in every ecosystem and complex ecosystem dynamics are a major topic in experimental ecology since the introduction of this concept (Standish et al 2014), the interaction between abiotic triggers and biotic community response remains rarely studied for uncontrolled, natural systems
Summary
A multitude of abiotic and biotic non-linear dynamics and interactions modified by historical events qualify ecosystems to be complex adaptive systems (Gell-Mann 1994, Levin 1998, Norberg 2004). Complexity is inherent in every ecosystem and complex ecosystem dynamics are a major topic in experimental ecology since the introduction of this concept (Standish et al 2014), the interaction between abiotic triggers and biotic community response remains rarely studied for uncontrolled, natural systems. The temporal response of an ecological community to a certain disturbance can be simplified in a two dimensional model characterized by ecological resilience and elasticity (cf Holling 1973). Whereas elasticity quantifies the ability of an ecosystem to return to a stable state after disturbance (Grimm and Wissel 1997), ecological resilience defines the amount of disturbance an ecosystem can absorb without changing its actual state (Holling 1973, Gunderson 2000)
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