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Large wood debris recruitment on differing riparian landforms along a Gulf Coastal Plain (USA) stream: a comparison of large floods and average flows
Author(s) -
Golladay Stephen W.,
Battle Juliann M.,
Palik Brian J.
Publication year - 2007
Publication title -
river research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.679
H-Index - 94
eISSN - 1535-1467
pISSN - 1535-1459
DOI - 10.1002/rra.977
Subject(s) - floodplain , riparian zone , landform , debris , hydrology (agriculture) , coastal plain , flood myth , coarse woody debris , debris flow , streams , large woody debris , channel (broadcasting) , geology , flooding (psychology) , environmental science , fluvial , physical geography , geography , ecology , geomorphology , habitat , oceanography , archaeology , structural basin , psychotherapist , computer network , computer science , engineering , biology , psychology , paleontology , cartography , geotechnical engineering , electrical engineering
In southeastern Coastal Plain streams, wood debris can be very abundant and is recruited from extensive forested floodplains. Despite importance of wood debris, there have been few opportunities to examine recruitment and redistribution of wood in an undisturbed setting, particularly in the southeastern Coastal Plain. Following extensive flooding in 1994, measurements of individual downed trees (species, dbh, orientation, distance from base‐flow channel and condition) were made across replicated riparian landforms in a Gulf Coastal Plain 5th‐order stream. Annually, the fate of these trees was determined and newly recruited trees were noted. More than 300 downed trees have been recorded. Recruitment varied across landforms with more constrained reaches having greatest mortality. Total tree mortality varied substantially across years. Generally, tree recruitment was greatest in years with substantial floods (1994 and 1998). For each riparian landform type, tree mortality was correlated with the maximum daily flow during the period preceding annual debris surveys. This relationship was particularly strong for sand ridges ( r 2 = 0.942) and low terraces ( r 2 = 0.915), but was significant for floodplains ( r 2 = 0.413). Greatest rates of debris recruitment per maximum daily flow were observed for sand ridges followed by low terraces. Flood characteristics also influenced debris recruitment. The 1994 flood was caused by a tropical storm and resulted in a rapid rise in streamflow. Much of the debris recruited during this flood was from toppled trees and was oriented parallel to the stream channel. In contrast, the 1998 flood was preceded by a wetter than average winter with more gradually rising flows and there was no relationship between riparian landform and debris characteristics. These results indicate that wood recruitment dynamics in Coastal Plain streams are complex. Wood recruitment rates are controlled by cyclical variations in climate interacting with riparian geomorphology. Infrequent high flows appear critical in the maintenance of the instream debris pool. Copyright © 2007 John Wiley & Sons, Ltd.