A dendrogeomorphic approach to measurement of sedimentation in a forested wetland, Black Swamp, Arkansas

Abstract

Dendrogeomorphic techniques were used to describe and interpret the spatial and temporal patterns of sedimentation in the Black Swamp, located along the Cache River in eastern Arkansas. At 30 sites along four transects, 148 trees were examined for depth of sediment accretion and cored for age determination. Tree-ring and geomorphic analyses indicated that mean sedimentation rates were significantly related to site elevation, topographic position, and the distribution of tupelo gum and bald cypress. Maximum mean rates of sedimentation, as high as 0.60 cm/yr, generally occurred in sloughs, areas low in elevation, and where tupelo gum and bald cypress grow. Mean sedimentation rate appeared to have a negative exponential relation with increasing elevation. Tree-agc class data indicated a significant increase in sedimentation rate since about 1945, from a mean at or below 0.01 cm/yr to a mean of 0.28 cm/yr for the past 19 years. Dendrogeomorphic techniques provide valid estimates of sedimentation rate and allow for the integration of decades of depositional processes in the rate calculation.