Date of Award

5-6-2000

Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

Biology

First Advisor

Dr. Thomas Bragg

Abstract

Vegetation and soils of interdunal depressions were compared to those of adjacent north-facing slopes that represent the upland matrix of the Nebraska Sandhills Prairie. Data from canopy cover and biomass show interdunal depressions to be more variable in species composition but significantly lower in diversity than north-facing slopes (H’ = 1.294 and 1.451, respectively). Significant differences (P < 0.05) were observed for total plant cover (95% depression, 87% slope), grass cover (80% and 69%), total biomass (150 g/m2 and 120 g/m2), and grass biomass (110 g/m2 and 70 g/m2). Belowground biomass was higher in depressions, although not significantly so (8 g/m2 and 3 g/m2). The plant communities of depressions were dominated by Scribner’s dichanthelium (Dichantheliuum oligosanthes var. scribneriamum) (32% cover), sedges (Carex spp. And Cyperus schweinitzii) (27% cover), little bluestem (Andropogon scoparius) (21% cover), and white sage (Artemisia ludoviciana) (19% cover). Little bluestem (27% cover), western ragweed (Ambroisa psilostachya) (17% cover), and junegrass (Koeleria pyramidata) (13% cover) dominated slope communities. Significant (P < 0.05) differences between depressions and slopes were recorded for soil moisture (3% and 2%), soil organic matter (2% and 1%), depth of humic acid staining (120 cm and 40 cm), and 3 of 7 soil particle sizes, including silt. Most of the 19 elements tested had higher concentrations in depressions, but significant differences were recorded for iron, potassium, manganese, silicon, and zinc. Significantly higher proportions of small mineral soil particles, organic matter, and nutrients suggest that depressions may act as a regional sink for air-borne particulates that, in combination with higher soil moisture, support a substantially different plant community than the surrounding prairie matrix. This, interdunal depressions appear to contribute significantly to the landscape-level diversity of the Sandhills Prairie ecosystem.

Comments

A Thesis Presented to the Department of Biology and the Faculty of the Graduate College University of Nebraska In Partial Fulfillment of the Requirements for the Degree Master of Arts University of Nebraska at Omaha. Copyright 2000 Danica Marie Kochis-Belleque.

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