Influence of heterogeneous subsoil development on vegetation patterns in a subtropical savanna parkland, Texas /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1989.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | A study was undertaken to determine (1) the extent and spatial relationships of soil variability to vegetation patterns in a South Texas savanna parkland, (2) the influence of soil properties on vegetation patterns, and (3) the origin of subsoil heterogeneity. An extensive soil-vegetation survey verified the spatial coincidence of mesquite groves (assemblages of large, old arboreal mesquite plants) and soils with lower clay content and cambic horizons. Soils supporting herbaceous vegetation, solitary shrub clusters, and clusters with dead mesquite contained argillic horizons and more clay. Morphological, physical, and chemical properties of Miguel (grassland) and Saspamco (mesquite grove) soils were quantified to determine their role in regulating mesquite grove development. Miguel argillic horizons had higher clay contents and bulk densities and strong blocky structure. These attributes combined to hinder air and water movement and root penetration, thereby favoring shallow-rooted grasses at the expense of deeper-rooted woody plants. Saspamco soils lacked such restrictive horizons; therefore, woody plants could exploit nutrient and moisture resources contained in deeper horizons to better survive herbaceous competition. Hypotheses explaining the origin of insular Saspamco soils within a matrix of Miguel soils were tested. The destruction of former argillic horizons via chemical obliteration or faunalturbation was rejected since argillic horizon remnants were not observed in Saspamco soils. Hypotheses involving burial of former landscapes were refuted because sedimentary discontinuities occurred at similar depths in both soils. Variable sedimentary deposition of parent materials could not be rejected. Although biologically perpetuated aridity was evident in most Saspamco soils, it was unnecessary for their genesis because leached cambic horizons occurred beneath some mesquite groves.. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Range Science." |
| Physical Description: | xiv, 243 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |