DOI: 10.5061/dryad.jn3rr
title: Data from: Quantifying flooding regime in floodplain forests to guide river restoration

description: Determining the flooding regime needed to support distinctive floodplain
 forests is essential for effective river conservation under the ubiquitous
 human alteration of river flows characteristic of the Anthropocene Era. At
 over 100 sites throughout the Connecticut River basin, the largest river
 system in New England, we characterized species composition, valley and
 channel morphology, and hydrologic regime to define conditions promoting
 distinct floodplain forest assemblages. Species assemblages were dominated
 by floodplain-associated trees on surfaces experiencing flood durations
 between 4.5 and 91 days/year, which were generally well below the stage of
 the two-year recurrence interval flood, a widely-used benchmark for
 floodplain restoration. These tree species rarely occurred on surfaces
 that flooded less than 1 day/year. By contrast abundance of most woody
 invasive species decreased with flooding. Such flood-prone surfaces were
 jointly determined by characteristics of the hydrograph (high discharges
 of long duration) and topography (low gradient and reduced valley
 constraint), resulting in increased availability of floodplain habitat
 with increasing watershed area and/or decreasing stream gradient.
 Downstream mainstem reaches provided the most floodplain habitat, largely
 associated with low-energy features such as back swamps and point bars,
 and were dominated by silver maple (Acer saccharinum). However, we were
 able to identify a number of suitable sites in the upper part of the basin
 and in large tributaries, often associated with in-channel islands and
 bars and frequently dominated by sycamore (Platanus occidentalis) and
 flood disturbance-dependent species. Our results imply that restoring
 flows by modifying dam operations to benefit floodplain forests on
 existing surfaces need not conflict with flood protection in some regional
 settings. These results underscore the need to understand how flow,
 geomorphology, and species traits interact to produce characteristic
 patterns of floodplain vegetation, and that these interactions should form
 the basis of effective river restoration and conservation.
description: Floodplain transect
 vegetation and geometry databaseMS Access database that
 contains all the vegetation and surveying data supporting the associated
 article. This database also includes information on linking other
 associated data files such as hydrologic models. Data include floodplain
 vegetation along belt transects such as tree species and elevations.
 Flooding regime as calculated by associated models is also summarized in
 the database.Read first notes on Connecticut
 River floodplain files.docxdb_CT_River_Floodplain_Vegetation.mdbCalculated river stage history files for transectsThis zip file contains comma delimited files of daily river stage data that were calculated for each floodplain research transect. The corresponding vegetation and elevation data can be found in the associated floodplain database tables.Notes on Connecticut River stage data.docxGIS transect locationsArcGIS and Google Earth files showing Connecticut River floodplain research transect locations. Please note these locations are provided for illustration and use in geographic analyses. Anyone wishing to do on the ground visits or field research at these sites needs to first obtain permission from the relevant landowners.Notes on Connecticut River floodplain research transect locations.docxHEC-RAS hydraulic model filesHEC-RAS hydraulic model files for floodplain forest research sites. The HEC-RAS software is available for free from the US Army Corps HEC at: http://www.hec.usace.army.mil/software/hec-ras/ . Model files were used to compute rating curves for each floodplain research transect as well as stream power and other flow measures.Hobo data logger daily stage dataDaily average river stage data calculated from pressure transducer measurements recorded by a Hobo data logger. Stage elevations are in the same coordinates as the vegetation elevation data in the accompanying database.