PARENT SESSION
Poster Session 7: Grasslands
Tuesday, August 9, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Rangeland manipulation by root plowing: Species richness and diversity 39 years post-treatment.
Lozano, E. Alejandro*,1, Fulbright, Timothy E.*,1, Ruthven, III, Donald C. 2, 1 Caesar Kleberg Wildlife Research Institute, Kingsville, Texas, USA2 Texas Parks and Wildlife Department, Austin, Texas, USA
ABSTRACT- Large root plows pulled by crawler tractors are commonly used to remove woody vegetation and increase grasses for livestock forage in Tamaulipan thornscrub; however, woody plants reestablish within 20 years following treatment. We estimated species richness, diversity, and evenness of herptofauna, small mammals, and vegetation in untreated habitats and in habitats root plowed 39 years previously. Five sites root plowed in 1965 and 5 nontreated sites with similar soils were selected for study in southern Texas. Herptofauna and small mammal species richness, diversity, and evenness were estimated using pitfall traps and Sherman live traps. Vegetation canopy cover and density were estimated using line intercepts and 0.1 m2 sampling frames. Herbaceous and woody vegetation species richness and Shannon's diversity index were similar (P > 0.05) on untreated and plowed areas. Evenness and beta diversity of herbaceous plants were similar (P > 0.05) between treatments, but evenness and beta diversity of woody plants were lower (P = 0.022 and P < 0.0001, respectively) on plowed sites because of greater relative abundance of Prosopis glandulosa and Acacia tortuosa. Species richness, Shannon's diversity index, and evenness of small mammals were similar (P > 0.05) on untreated and plowed areas. Species richness and Shannon's diversity index of herpetofauna were similar (P > 0.05) on untreated and plowed sites; however, evenness was lower (P = 0.047) on plowed sites because of reduced abundance of amphibians. Population size of small mammals was similar (P = 0.676) on untreated (67 ± 17) and plowed sites (50 ± 18); however, the population size of herpetofauna was lower (P = 0.09) on plowed areas (49 ± 18) than untreated areas (67 ± 17). Changes in Tamaulipan thornscrub communities resulting from one root plowing event appear to persist for at least four decades and include reduced habitat patchiness and loss of environmentally sensitive herptofauna.
Key words: Rangeland, Root plowing, Species richness, Diversity