The Effects of Floodplain Trees on Herbaceous Vegetation Patterns, Microtopography and Litter

Publisher Website
Google Scholar
Abstract
Variations in the density and distribution of herbaceous stems around floodplain trees and differences in density and distribution of herbs between samples around trees and samples > 2.5 m from trees are described. Estimates of soil surface levels for quadrats around trees are low as a result of depressions due to scouring, particularly on the downstream side of the trees. Litter cover estimates are high around trees as a result of accumulation on the upstream side of the trees. Repeated measures analysis of total herbaceous stem density in the quadrats shows the density at ground level is lower around trees than at points > 2.5 m from trees, is lower in quadrats 0-1 m from the trees than in quadrats 1-2 m from the trees, and is affected by direction of the quadrats in relation to waterflow around the trees. There were significantly fewer stems of Aster simplex in quadrats 0-1 m than in quadrats 1-2 m from the trees and the stem density of Laportea canadensis was affected by direction of the quadrats. There were fewer stems of L. canadensis, the dominant rhizomatous perennial, in quadrats downstream of trees than in quadrats upstream at ground level and in quadrats 0.5 m above ground. Observations on regeneration by L. canadensis suggest that the disturbance occurring around floodplain trees affects this species in the vegetative regeneration phase of its life history. Trees on floodplains create depressions as the result of periodic disturbance of the soil due to scouring by floodwaters, cause accumulation of litter, and have different affects on the establishment and pattern of herbaceous species, especially perennials.