Date of Award

7-1-1996

Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

Biology

First Advisor

Dr. Thomas Bragg

Abstract

Plant composition was compared between 3 restored and 3 natural Nebraska sandhill wetlands using plot data collected from each wetland in July and August of 1995 along five randomly placed, 25m transects. A total of 126 species were identified, of which 72 were found only in the natural area and 23 only in the restored area; the natural wetlands average 58 species and their restored 31. Cluster analysis of mean cover values, at a Euclidean Distance of 1000, identified five vegetative associations in the natural and three in the restored wetlands. In addition, cluster analysis of combined data indicated a complete separation of the restored and natural wetlands. Ordination of combined data showed a tight clustering of the restored area plots midway along the X-axis (xeric-hydric gradient; Eigenvalue 0.78) suggesting that the restored area represents only a portion of the total gradient of the natural area. Three Basic patterns of species distribution were identified based on the natural area data. Type I species distributions were characterized by Scirpus acutus which increased in canopy cover from being absent in the xeric upland to 18% cover in the hydric lowland. This species, however, was ubiquitous throughout the restored area averaging 2% cover. Eleocharis erythropoda characterized Type II species are both natural and restored wetlands with the highest canopy in central plots of the natural area transect (26%) and even higher (55%) in the restored area. Dichanthelium acuminatum var. implicatum typified Type III Species with a decrease in cover from xeric (11%) to absent in the hydric sites. Type III species were either absent. ANOVA and Sudent-Newman-Keuls multi comparison test of species with a frequency of at least 10% showed significant differences (p<0.05) among at least two or three restored or natural wetland plots for Agrostis stolonifera, Amberosia psilostachya, Elecharis acicularis, Eleocharis erythropoda, Eleocharis palustris, Lysicmachia ciliate, Lythrum alatum, Scripus acutus, Spartina pectinate, Suim suave, and Typha spp.. Based on community-level and species level analyses, the present study suggests that the restored Sandhill wetlands evaluated are not, presently, similar to natural wetlands and that it would be premature to suggest that the restorations are successful. Further, the results of this study suggest that serious wetland restoration efforts must ensure that basic abiotic (e.g. topographic) heterogeneity is provided in restoration sites. The difficulties, and probable costs, involve in ensuring successful wetland restoration should invite more serious efforts to prevent destruction of habitat.

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 1996 Warren Thomas Weaver.

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