Title: Multiple, Compounding Disturbances in a Forest Ecosystem: Fire Increases Susceptibility of Soil Edaphic Properties, Bacterial Community Structure, and Function to Change with Extreme Precipitation Event

Abstract

The intensity and frequency of ecosystem disturbances are shifting with climate change, and multiple disturbances in close succession have the potential to compound their independent effects and strongly alter ecosystem structure and function. In this paper, we examine the effects of an extreme precipitation event on a montane forest landscape that was previously decimated by wildfire (37 months prior) relative to an unburned site in the same ecosystem. We assessed responses in soil edaphic properties, bacterial community composition and assembly, and soil enzyme activities involved in carbon (C) and nitrogen (N) acquisition. Our research reveals that previously burned landscapes are susceptible to a subsequent extreme precipitation event via significant increases in soil pH where unburned soils are not. Beta- and Delta-proteobacteria associated with early succession increased and shifts were observed in N- vs. C-acquiring extracellular enzymes within burned soils after the extreme precipitation event. Finally, we connected variation in ecological selective pressures on bacterial communities associated with pH change to these differences in microbial mediated soil enzyme activity. Thus, this research demonstrates how multiple, compounding disturbances drive distinct changes relative to systems experiencing a single disturbance and suggests that changes in bacterial community assembly process with disturbance may underlie thismore » response.« less

Authors:

Knelman, Joseph E. ^[1]; Schmidt, Steve K. ^[1]; Garayburu-Caruso, Vanessa ^[2]; Kumar, Swatantar ^[2]; Graham, Emily B.  ^[2]

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+ Show Author Affiliations

1. Univ. of Colorado, Boulder, CO (United States)
2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Publication Date:

2019-06-12

Research Org.:

Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)

OSTI Identifier:

1582597

Report Number(s):

PNNL-SA-144296
Journal ID: ISSN 2571-8789

Grant/Contract Number:  

AC05-76RL01830

Resource Type:

Accepted Manuscript

Journal Name:

Soil Systems

Additional Journal Information:

Journal Volume: 3; Journal Issue: 2; Journal ID: ISSN 2571-8789

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; multiple disturbances; microbial community assembly; flood; soil; bacterial community; carbon cycle; nitrogen cycle; extracellular enzyme activity; selection