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Forest understory plant and soil microbial response to an experimentally induced drought and heat‐pulse event: the importance of maintaining the continuum
Author(s) -
Rein Isabell,
Gessler Arthur,
Premke Katrin,
Keitel Claudia,
Ulrich Andreas,
Kayler Zachary E.
Publication year - 2016
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.13270
Subject(s) - microbial population biology , understory , environmental science , fagus sylvatica , beech , soil carbon , climate change , plant community , carbon cycle , biology , soil water , ecology , canopy , agronomy , ecosystem , botany , ecological succession , bacteria , genetics
Drought duration and intensity are expected to increase with global climate change. How changes in water availability and temperature affect the combined plant–soil–microorganism response remains uncertain. We excavated soil monoliths from a beech ( Fagus sylvatica L.) forest, thus keeping the understory plant–microbe communities intact, imposed an extreme climate event, consisting of drought and/or a single heat‐pulse event, and followed microbial community dynamics over a time period of 28 days. During the treatment, we labeled the canopy with 13 CO 2 with the goal of (i) determining the strength of plant–microbe carbon linkages under control, drought, heat and heat–drought treatments and (ii) characterizing microbial groups that are tightly linked to the plant–soil carbon continuum based on 13 C‐labeled PLFA s. Additionally, we used 16S rRNA sequencing of bacteria from the Ah horizon to determine the short‐term changes in the active microbial community. The treatments did not sever within‐plant transport over the experiment, and carbon sinks belowground were still active. Based on the relative distribution of labeled carbon to roots and microbial PLFA s, we determined that soil microbes appear to have a stronger carbon sink strength during environmental stress. High‐throughput sequencing of the 16S rRNA revealed multiple trajectories in microbial community shifts within the different treatments. Heat in combination with drought had a clear negative effect on microbial diversity and resulted in a distinct shift in the microbial community structure that also corresponded to the lowest level of label found in the PLFA s. Hence, the strongest changes in microbial abundances occurred in the heat–drought treatment where plants were most severely affected. Our study suggests that many of the shifts in the microbial communities that we might expect from extreme environmental stress will result from the plant–soil–microbial dynamics rather than from direct effects of drought and heat on soil microbes alone.