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Threshold effects of flood duration on the vegetation and soils of the Upper Mississippi River floodplain, USA

Forest Ecology and Management

By:
, ,
DOI: 10.1016/j.foreco.2012.01.023

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Abstract

Most large rivers have experienced major changes in hydrology and land use over the past century, with concomitant effects on sedimentation, nutrient cycling and biodiversity. To restore and/or enhance these ecosystems, managers need to know where their efforts are most likely to succeed under current hydrologic regimes as well as under potential future hydrologic regimes. We therefore examined changes in forest vegetation and soils across a hydrologic gradient, expressed as flood duration during the growing season, for 320 km of the Upper Mississippi River (UMR) floodplain.

Soil texture was highly variable but trended toward finer grained sediments and >5% organic matter as flood duration increased from 0% to ~40% of the growing season. Beyond 40%, soil texture was exclusively silt plus clay with >5% organic matter. The diversity of both the understory and overstory tree communities was also highly variable at sites that flooded for <40% of the growing season. However, understory diversity decreased as flood duration increased from 0% to ~25% of the growing season and overstory diversity declined as flood duration increased from 0% to ~40% of the growing season. Diversity estimates for both strata were uniformly low at sites that flooded for longer than ~40% of the growing season. Beyond this point the proportional abundance of Acer saccharinum in the overstory exceeded 70%.

Our results suggest that there is a threshold along the elevation gradient of this floodplain, corresponding with flood durations lasting ~40% of the growing season. At lower elevation sites, flooding exerts primary control over forest soils and vegetation, restricting the former to silt plus clay with higher organic matter and the latter to a few highly flood tolerant species. The existence of such thresholds have implications for management of floodplain soil nutrient dynamics and plant diversity under existing hydrologic regimes, more natural hydrologic regimes and more extreme hydrologic regimes that may result from climate change.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Threshold effects of flood duration on the vegetation and soils of the Upper Mississippi River floodplain, USA
Series title:
Forest Ecology and Management
DOI:
10.1016/j.foreco.2012.01.023
Volume
270
Year Published:
2012
Language:
English
Publisher:
Elsevier
Publisher location:
Amsterdam, Netherlands
Contributing office(s):
Upper Midwest Environmental Sciences Center
Description:
12 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
135
Last page:
146
Country:
United States
State:
Iowa;Minnesota;Wisconsin
Other Geospatial:
Upper Mississippi River Floodplain