The Role of Animals in the Persistence of Desertified Ecosystems

Project Number:

02R-15

Project Duration:

30 months

Dates:

May 1, 2002 to October 31, 2004

Institution of Principle Investigator while on this project:

New Mexico State University

Investigators (most current known information)

Whitford, Walter G. (PI)

USDA Agricultural Research Service, Jornada Experimental Range, Las Cruces NM 88003

TEL: +1-505-646-8032, FAX: +1-505-646-5889, Email: wawhitfo@nmsu.edu

Roemer, Gary W.

Assistant Professor, Department of Fishery & Wildlife Sciences, New Mexico State University, Box 30003, MSC 4901, Las Cruces NM 88003-8003

TEL: +1-575-646-3394, FAX: +1-575-646-1281, Email: groemer@nmsu.edu

Steinberger, Yosef

Professor, Bar-Ilan University, Faculty of Life Sciences, Ramat Gan 52900, ISRAEL

TEL: +972-3-531-8571, FAX: +972-3-535-1824, Email: steinby@mail.biu.ac.il

Proposal Abstract

The researchers conducted experiments to examine microsite and rodent influence on mesquite (Prosopis glandulosa) germination and survival in Chihuahuan Desert black-grama (Bouteloua eriopoda) grassland. Simulated caches with mesquite seeds were placed in undisturbed grassland, burned grassland patches with reduced grass cover, and on the periphery of kangaroo rat mounds. Rodents access to cached seeds was controlled by covering half of the caches with mesh domes. Kangaroo rats destroyed dung pats containing scarified mesquite seeds and excavated all seeds in simulated caches during a year in which no grasses or forms set seed. Germination was highest in unburned grassland, but over winter survival was only observed across experiments in burned grassland microsite. A large proportion of seed caches were excavated (1.1 - 5.5% of the rodent excluded caches and between 15.6 - 21.1% of the control caches). There were seasonal differences in numbers of emergent seedlings, with a peak in September 2002 following late summer rains. There were no significant differences in numbers of germinate in burned and unburned grassland microsite, but significantly fewer mesquite seeds germinated on banner-tail kangaroo rat mounds. Caches excavated by rodents yielded 46.6% of germinate. This study suggests that scarification of mesquite seeds is not necessary for germination and heteromyid rodents may be responsible for increased mesquite density in grasslands with some mature mesquite plants. The data also suggest that competition between mesquite seedlings and grasses in black-grama grassland is weak because of the physical characteristics of this system.

Outcome

Presentations

Roth, G.A., W.G. Whitford, and Y. Steinberger. 2004. Desertification in historical perspective: Of man and other ecosystem engineers in the arid southwestern USA. In Zoological Society of Israel 41st annual meeting. Haifa, Israel. December (oral presentation).

Mathis, V.L., W.G. Whitford, F.R. Kay, and P.U. Alkon. 2004. Effects of grazing and shrub removal on small mammal populations in southern New Mexico. In 6th Chihuahuan Desert Symposium. Alpine TX. October.

Duval, B., E. Jackson, and W.G. Whitford. 2004. Mesquite establishment in Chihuahuan Desert grasslands: effects of banner-tail kangaroo rats and hervibory. In 6th Chihuahuan Desert Symposium. Alpine TX. October.

Roth, G.A., W.G. Whitford, and Y. Steinberger. 2004 The role of animals in desertification: Herbivory patterns in degraded grassland. In Ecological Society of America 89th annual meeting . Portland OR. 6 August (oral presentation).

Roth, G.A. W.G. Whitford, and Y. Steinberger. 2004. The role of animals in desertification: Hervibore-induced vegetation change. In Wildlife Society 9th annual meeting. Calgary, Alberta, Canada. 22 September (oral presentation).

Roth, G.A., W.G. Whitford, and Y. Steinberger. 2003. The role of animals in landscape shaping in desertified ecosystems. In Zoological Society of Israel 40th annual meeting . Sde-Boker, Israel. December (oral presentation).

Articles in Journals

Duval, B.D., E. Jackson, W.G. Whitford. 2004. “Mesquite ( Prosopis Gladulosa ) germination and survival in lack-grama (Bouteloua Eriopoda) grassland: relations between Microsite and Heteromyid rodent (Diposomys spp.) impact.” Journal of Arid Environments. (in press).

Mathis, V.L., W.G. Whitford, F.R. Kay, and P.U. Alkon. 2004. “Effects of grazing and shrub removal on small mammal populations in southern New Mexico.” (in preparation).

Mathis, V.R., W.G. Whitford, F.R. Kay, and P.U. Alkon. 2004. “Effects of grazing and shrub removal on small mammal populations in southern New Mexico.” (in review to Journal of Arid Environments).

Roth, G.A., W.G. Whitford, and Y. Steinberger. 2004. “The role of jackrabbits (Lepus californicus) in vegetation change associated with desertification in the Northern Chihuahuan Desert.” (in preparation).

author(s). 2004. “Harvesting of grass flowering tillers by heteromyid rodents: effects of grazing and shrub removal.” (in preparation for submission to Journal of Arid Environments ).

author(s). 2004. “Mesquite girdler (Insecta: Coleopters: Cerambycidae) effect on stem density of mesquite ( Prosopis glandulosa ): Implications for desertification.” (in preparation for submission to Nature ).

Master's Thesis

Duval, B.D. 2004. Ecosystem engineering by black-tailed prairie dogs (Cynomys ludovicianus): Implications for arthropod assemblage structure and burrowing owl (Athene cunicvularia) foraging. Masters Thesis.