Spatial and temporal vegetation patterns in a subtropical Prosopis savanna woodland, Texas /
| Main Author: | |
|---|---|
| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1988.
|
| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | Woody plant density and canopy cover in discrete clusters formed beneath Prosopis glandulosa (honey mesquite) increased as basal diameter of P. glandulosa increased. Within clusters, abundance of other woody plants decreased with increasing distance from P. glandulosa. Woody species richness also increased with cluster size with establishment of evergreen shrubs preceding that of deciduous fruticose shrubs. Zonation of woody vegetation in mature clusters was such that 1) Opuntia lindheimeri and deciduous suffrutescent shrubs were most prominent at cluster margins; 2) arboreal legumes (apart from central P. glandulosa) were uncommon within clusters; 3) deciduous and evergreen fruticose shrubs were most abundant near cluster centers; and 4) clusters had little effect on herbaceous composition and standing crop in interspaces. Herbaceous species richness within clusters decreased with cluster development and increased with distance from the central P. glandulosa plant. Herbaceous biomass had increased 20 months after shrubs in clusters were treated with herbicide. When shrubs were cut at ground level, woody regrowth was rapid and herbaceous production unaffected. Leaving shrub skeletons in herbicide treated clusters resulted in higher herbaceous standing crop than in clusters where herbicide was applied to shrub stumps after top removal. Soil water at depths >35 cm was lowest in intact mature clusters, highest in interspaces and intermediate in top-removal clusters. Cenchrus ciliaris (buffelgrass) plants grown in potted soil collected from cluster centers were taller, produced more tillers and had greater shoot and root biomass than plants grown on interspace soils. The data indicated 1) a spatial gradient from interspaces to cluster centers, characterized by zonation of herbaceous and woody vegetation; and 2) a temporal gradient of cluster development, evidenced by the magnitude of departure of vegetative and edaphic characteristics of interspaces which increased with increasing cluster size. Both gradients appear to parallel the length of time shrubs have inhabited a location. Marked differences in woody and herbaceous vegetation of cluster chronosequences necessitate their designation as discrete landscape subunits. The implications for assessing and projecting herbaceous productivity following manipulation of woody vegetation are discussed. |
|---|---|
| Item Description: | Typescript (photocopy). Vita. "Major subject: Range Science." |
| Physical Description: | xvi, 139 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references (leaves 108-116). |