@article {JRN54560, title = {Defoliation of Flourensia cernua (tarbush) with high-density mixed-species stocking}, journal = {Journal of Arid Environments}, volume = {130}, year = {2016}, month = {04/2016}, pages = {62-67}, chapter = {62}, abstract = {

Interest in shrub use by livestock is increasing along with the rising demands placed on rangelands worldwide. Historically, Flourensia cernua (tarbush) has increased in the Chihuahuan Desert but receives limited use by cattle. Cattle, sheep and goats co-grazed eight 0.6 ha tarbush-dominated paddocks during two periods for up to nine days during two consecutive years. Cumulative tarbush defoliation across periods and years averaged 75.6\%, with a mean increase of 9.3\%/day (P \< 0.0001). Defoliation of individual shrubs varied from 5 to 99\% in 1989 and 0 - 100\% in 1990, indicating highly variable palatability among individual plants. Sheep lost 2.3 - 5.5 kg/hd (P \< 0.0001) across periods and years when forced to browse tarbush. In 1989, goats gained (P . 0.0345) 0.6 kg/hd in period 1, but the gain in period 2 was not significant (P . 0.2934). During 1990, goats lost 3.1 kg/hd (P . 0.0001) across periods. High-density mixed-species stocking of small areas for short time periods resulted in extensive tarbush use, primarily due to browsing by sheep and goats. Targeted use of tarbush for short time intervals may increase use of this highly nutritious forage and potentially serve as a form of biocontrol for this shrub.

}, keywords = {biocontrol, browsing, cattle, goats, sheep, shrubs}, doi = {10.1016/j.jaridenv.2016.03.013}, url = {/files/bibliography/16-008.pdf}, author = {Richard E. Estell and D.M. Anderson and D. K. James} } @proceedings {49962, title = {Examining endophyte interactions within fourwing saltbush (Atriplex canescens)}, volume = {XVI}, year = {2011}, month = {06/2011}, pages = {159-164}, publisher = {The Berkeley Electronic Press}, address = {Bozeman, Montana}, abstract = {Cryptic endophyte consortia associated with embryonic tissues of fourwing saltbush (Atriplex canescens) are believed to serve mutualistic functions. However, the complexity of these endophyte communities makes cause-and-effect relationships difficult to establish. In fourwing saltbush, cryptic endophytes are thought to enhance drought and salt tolerance, nutrient acquisition, germination, and establishment. Some of these traits can be conferred to alternate host plants by co-culturing seedlings in vitro with micropropagated fourwing saltbush callus. Here we describe an evolving process for; 1) identifying arrays of cryptic, seed borne endophytes associated with fourwing saltbush; 2) evaluating early vigor of grasses and other plants endowed with fourwing saltbush endophytes; 3) selecting plant-endophyte combinations with increased tolerance to abiotic stressors, and 4) monitoring the persistance of transferred endophytes across plant generations in increasingly complex habitats. This process is designed to evaluate specific plant-fungal interactions that influence host tolerance to salinity, but may be broadly adaptable for selecting endophyte-enhanced plant germplasms with a variety of desired traits.}, keywords = {Atriplex canescens, browsing, cryptic endophyte consortia, embryonic, fire, herbivory, monitoring, proceedings, sagebrush, wildland shrubs}, url = {/files/bibliography/08-056.pdf}, author = {M.E. Lucero and J.R. Barrow and I. Reyes-Vera and Ruth L. Sedillo} } @article {50140, title = {Small mammal herbivory: Feedbacks that help maintain desertified ecosystems}, journal = {Journal of Arid Environments}, volume = {73}, number = {73}, year = {2009}, month = {01/2009}, pages = {62-65}, chapter = {62}, abstract = {

We tested the hypothesis that herbivores contribute to feedbacks maintaining arid ecosystems in a degraded state. We studied small mammal herbivory on a subshrub, broom snakeweed (Gutierrezia sarothrae), and perennial grasses at three sites: (1) ungrazed black grama (Bouteloua eriopoda) grassland; (2) grassland degraded by intense short-duration grazing; and (3) mesquite (Prosopis glandulosa) coppice dunes. Snakeweed was browsed by herbivores primarily during dry winter months. The average percent of G. sarothrae standing crop biomass removed by browsing was 9.2 in ungrazed grassland, 7.4 in intensely grazed grassland, and 4.1 in the dunes. In ungrazed grassland, an average of 12\% of grass cover was harvested by herbivores; in the intensely grazed plots \– 80\%. Herbivore exclusion plots showed that jackrabbits (Lepus californicus) were the primary browsers on snakeweed and rodents on grasses and G. sarothrae inflorescences. Rodent removal of G. sarothrae inflorescences allows wind dispersal of seeds in disturbed and desertified areas, thereby increasing abundance of this poisonous shrub. Grass-tiller cutting by rodents provides a strong feedback that may be responsible for keeping the grass cover low on the intensely grazed areas. Jackrabbit pruning has little effect on G. sarothrae abundance at any stage of desertification.

}, keywords = {browsing, desertification, herbivory, jackrabbit, livestock grazing, snakeweed}, doi = {10.1016/j.jaridenv.2008.09.003}, url = {/files/bibliography/09-001.pdf}, author = {Roth, G.A. and Walter G. Whitford and Yosef Steinberger} } @article {50380, title = {Jackrabbit (Lepus californicus) herbivory changes dominance in desertified Chihuahuan Desert ecosystems.}, journal = {Journal of Arid Environments}, volume = {70}, year = {2007}, month = {03/2007}, pages = {418-426}, abstract = {This study addressed the question: can herbivory by a medium size herbivore, black-tail jackrabbits (Lepus californicus), change dominance in desertified ecosystems dominated by two species of shrubs. Shrubs that were pruned by jackrabbits in plant communities dominated by creosotebush (Larrea tridentate) and tarbush (Flourensia cernua) were compared to shrubs not browsed by the rabbits. In the missed shrub area, herbivory on F. cernua resulted in death of 46.6\% of the shrubs, compared to only 4.8\% of L. tridentate shrubs. There was no evidence of jackrabbit browsing of dead F. cernua in a tarbush monoculture area. The canopy volumes of F. cernua plants that survived repeated browsing were significantly smaller than predicted based on unbrowsed plants with the same basal stem areas. Jackrabbit browsing resulted in increased canopy volume of creosotebush shrubs. Creosotebush average canopy volume significantly exceeded predicted values because of compensatory growth of stems from nodes below the severed point. Close spatial association of lightly browsed creosotebush with heavily browsed tarbush may be a factor contributing to low utilization of creosotebush stems by jackrabbits. Differential browsing by the rabbits is shifting thee ecosystems toward an L. tridentate monoculture.}, keywords = {browsing, compensatory growth, creosotebush, Flourensia cernua, Larrea tridentata, preferential feeding, tarbush}, doi = {10.1016/j.jaridenv.2007.01.009}, url = {/files/bibliography/07-016.pdf}, author = {Roth, G.A. and Walter G. Whitford and Yosef Steinberger} }