Some Impacts of 2,4,5-T on a Mesquite Duneland Ecosystem in Southern New Mexico: A Synthesis

Gibbens, R; Herbel, C; Morton, H; Lindemann, W; Ryder-White, J; Richman, D; Huddleston, E; Conley, W; Davis, C; Reitzel, J; Anderson, D; Guiao, A

Two aerial rpplications of 2,4,5-T [(2,4,5-trichiorophenoxy) acetic acid] were applied to 3,634 ha of mesquite (Prosopisglandulosa Torr. var. gfandu~osa) duneiands in southern New Mexico. Herbicide residuals, herbaceous plant production; soil mlcroorganisms; insect, small mammal, and bird populations; cattle weights; travel; time budgets; and diets were studied on the treated area and adjacent, untreated area. Stem kill of mesquite ranged from 17-66%. Herbicide residuals in soils and plant tissue on the treated area dissipated within a single season. Herbrceous plant production was measured for 5 years on I small area sprayed in 3 consecutive years and on untreated rangeland. Production was greater on the sprayed than on the unsprayed area for the first 3 years and was about the same on both areas for the next 2 years. Microbial populations were not numerkally diierent between treatments but dehydrogennse activity and COZ evolution were greater in dunal than interdunnl soils. Numbers of tenebrionid beetles (Coleoptera: Tenebrionidae) did not differ between treatments. More mesquite leaf tiers (Tetrdopha euphemellla) were found on the sprayed area than on the untreated area. Population statistics for small mammals were similar on both treatments. More bird species were found on untreated than on sprayed areas. Cattle weights, travel, and time budgets did not differ between treatments and there were only minor differences between treatments in cattle diet quality. The sprayed area supported over twice as many AUMÆs of grazing the untreated area in the first 3 post-treatment years. In the second post-treatment year, cattle liveweight produced was 2.9 and 1.5 kg/ha on the sprayed and untreated areas, respectively. Overall, the 2,4,5-T treatment caused relatively minor perturbations in measured ecosystem components

Some Impacts of 2,4,5-T on a Mesquite Duneland Ecosystem in Southern New Mexico: A Synthesis

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