Habitat patchiness, ecological connectivity and the uneven recovery of boreal stream ecosystems from an experimental drought.,Global Change Biology

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Habitat patchiness, ecological connectivity and the uneven recovery of boreal stream ecosystems from an experimental drought.
Global Change Biology ( IF 10.8 ) Pub Date : 2020-03-29 , DOI: 10.1111/gcb.15063
Amélie Truchy ₁ , Romain Sarremejane _{2,

3} , Timo Muotka _{2,

4} , Heikki Mykrä ₄ , David G Angeler _{1,

5} , Kaisa Lehosmaa ₂ , Ari Huusko ₆ , Richard K Johnson ₁ , Ryan A Sponseller ₇ , Brendan G McKie ₁

Affiliation

Ongoing climate change is increasing the occurrence and intensity of drought episodes worldwide, including in boreal regions not previously regarded as drought prone, and where the impacts of drought remain poorly understood. Ecological connectivity is one factor that might influence community structure and ecosystem functioning post-drought, by facilitating the recovery of sensitive species via dispersal at both local (e.g. a nearby habitat patch) and regional (from other systems within the same region) scales. In an outdoor mesocosm experiment, we investigated how impacts of drought on boreal stream ecosystems are altered by the spatial arrangement of local habitat patches within stream channels, and variation in ecological connectivity with a regional species pool. We measured basal ecosystem processes underlying carbon and nutrient cycling: (a) algal biomass accrual; (b) microbial respiration; and (c) decomposition of organic matter, and sampled communities of aquatic fungi and benthic invertebrates. An 8-day drought event had strong impacts on both community structure and ecosystem functioning, including algal accrual, leaf decomposition and microbial respiration, with many of these impacts persisting even after water levels had been restored for 3.5 weeks. Enhanced connectivity with the regional species pool and increased aggregation of habitat patches also affected multiple response variables, especially those associated with microbes, and in some cases reduced the effects of drought to a small extent. This indicates that spatial processes might play a role in the resilience of communities and ecosystem functioning, given enough time. These effects were however insufficient to facilitate significant recovery in algal growth before seasonal dieback began in autumn. The limited resilience of ecosystem functioning in our experiment suggests that even short-term droughts can have extended consequences for stream ecosystems in the world's vast boreal region, and especially on the ecosystem processes and services mediated by algal biofilms.

中文翻译：

生境斑块，生态连通性和实验干旱导致的北流生态系统恢复不平衡。

持续的气候变化正在增加全球干旱事件的发生和强度，包括在以前不被认为容易发生干旱的北方地区以及人们对干旱的影响了解甚少的地区。通过促进在本地（例如附近的栖息地斑块）和区域（从同一地区的其他系统）范围内的扩散，恢复敏感物种的恢复，生态连通性是可能影响干旱后社区结构和生态系统功能的一个因素。在一个室外中观试验中，我们研究了干旱对河道生态系统的影响如何通过河道内局部生境斑块的空间排列以及与区域物种库的生态连通性变化而改变。我们测量了碳和养分循环的基础生态系统过程：（a）应计藻类生物量；（b）微生物呼吸；（c）有机物的分解以及水生真菌和底栖无脊椎动物的采样群落。一场为期8天的干旱事件对群落结构和生态系统功能都产生了重大影响，包括藻类积累，叶片分解和微生物呼吸，其中许多影响甚至在恢复水位3.5周后仍持续存在。与区域物种库的增强的连通性和栖息地斑块的增加聚集也影响了多个响应变量，尤其是与微生物相关的响应变量，在某些情况下，在一定程度上降低了干旱的影响。这表明，如果有足够的时间，空间过程可能会在社区的复原力和生态系统功能中发挥作用。但是，这些影响不足以促进藻类生长在秋季开始季节性死亡之前的显着恢复。在我们的实验中，生态系统功能的恢复能力有限，这表明即使是短期干旱也可能对世界广大的寒带地区的河流生态系统，尤其是对藻类生物膜介导的生态系统过程和服务产生更大的影响。

更新日期：2020-03-02

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