Structure, Composition, and Regeneration of Cross Timbers Forest Fragments in Different Land Use Contexts
STRUCTURE, COMPOSITION, AND REGENERATION OF CROSS TIMBERS FOREST FRAGMENTS IN DIFFERENT LAND USE CONTEXTS Ingrid Dunn Thesis Prepared for the Degree of MASTER OF SCIENCE UNIVERSITY OF NORTH TEXAS May 2015 APPROVED: Alexandra Ponette-González, Major Professor Mathew Fry, Committee Member C. Reid Ferring, Committee Member Paul Hudak, Chair of the Department of Geography Mark Wardell, Dean of the Toulouse Graduate School Dunn, Ingrid. Structure, Composition, and Regeneration of Cross Timbers Forest Fragments in Different Land Use Contexts. Master of Science (Applied Geography), May 2015, 85 pp., 17 tables, 12 figures, references, 120 titles. Throughout its current range, the Cross Timbers forest ecosystem is vulnerable to land- use change. In this study, we examined the surrounding land use matrix on the vegetation structure, composition and regeneration of six Cross Timbers forest fragments in Denton County, Texas (north of the Dallas-Fort Worth metroplex). Two fragments adjacent to agricultural land, two to residential neighborhoods, and two formally protected forest sites were selected. In summer 2015, five 100 m2 plots were randomly established in each fragment at least 200 meters from the edge. In each plot, all live and dead trees ≥ 3 cm diameter were identified and their height and diameter at breast height (DBH at 1.3 m aboveground) measured. Evidence of dumping (presence of trash) was recorded as an index of human frequentation. Differences in vegetation structure among the forest fragments were found. Most notably, fragments adjacent to agriculture contained 25% to 50% fewer trees per hectare than all other sites (Kruskal-Wallis, p < 0.02), especially trees <10 cm DBH.
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