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Carol A. Johnston
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Shrub cover was quantified by species for a 1.9-ha shrub carr adjacent to White Clay Lake near Shawano, WI, USA and related to soil properties and sedimentation rates. Principal components analysis of soil characteristics distinguished two distinct groups: alluvial surface soils having organic matter contents less than 30 g/100g and histic surface soils having organic matter contents averaging 56 g/100g. The alluvial surface soils were on slightly elevated natural levees along a relict stream bed that had received 1.3 cm/yr of silty sediments from agricultural runoff. Alluvial surface soils had twice the bulk density and organic P concentrations, nearly three times the reactive P, and 4.5 times the NO3-N concentrations of histic surface soils. Total shrub cover and shrub overlap was significantly greater on the alluvial surface soils, but there was no difference between the two soil groups in proportion of open space, suggesting that the increased total shrub cover on alluvial surface soils was due to increased shrub layering rather than infilling of canopy gaps. Shrub diversity was greater on the alluvial surface soils: average shrub species richness per 30.5 m line segment was five species on alluvial surface soils as opposed to three species on histic surface soils. Four willow species were strongly associated with the alluvial surface soils and may serve as indicators of sediment deposition: Salix discolor, S. eriocephala, S. interior, and S. lucida. The most common shrub species present, Cornus sericea spp. sericea and Salix petiolaris, were poor indicators of soil conditions within the wetland.

Carol A. Johnston "SHRUB SPECIES AS INDICATORS OF WETLAND SEDIMENTATION," Wetlands 23(4), 911-920, (1 December 2003).[0911:SSAIOW]2.0.CO;2
Received: 25 November 2002; Accepted: 1 August 2003; Published: 1 December 2003