|Nash, M - US-EPA|
|Anderson, J - NEW MEXICO STATE UNIV|
Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 1, 1998
Publication Date: N/A
Interpretive Summary: During the past one and one-half centuries, there have been widespread changes in the vegetation structure and capacity of Chihuahuan Desert grasslands to support livestock. In the Chihuahuan Desert, subterranean termites play very important roles as decomposers of dead plant materials, in the cycling of soil nutrients and as agents enhancing water movement into soil and water storage in soil. Termite activity was studied at 12 sites that differed in vegetation composition from grassland to shrubs on gravelly soils and sand dunes around shrubs. Studies were conducted for 6 consecutive years. There was no effect of vegetation or rangeland degradation on termite activity. There was a relationship between termite activity and rainfall, especially winter-spring rainfall. This study demonstrates that major vegetation changes and rangeland degradation do not necessarily result in major changes in other components of the ecosystem.
Technical Abstract: The annual feeding activity on paper baits of subterranean termites in desertified (degraded-shrub dominated ecosystems) and relatively undegraded black-grama (Bouteloua eriopoda) grasslands was measured over 6 years on 12 sites. There were no significant differences in mass losses from termite baits among the desertified and undesertified sites. Mass of paper consumed by termites on two sites dominated by creosotebush, Larea tridentata, was higher than on the other 10 sites. These sites were characterized by shallow, coarse soils and shrubs that did not retain a below-canopy litter layer. The spatial locations of the highest termite bait removal remained relatively constant over the duration of the study. Interannual variations in mass losses from termite baits were highly correlated with winter-spring rainfall (r**2 between 0.60 and 0.95) except at one site on shallow soils. The relationship between annual rainfall and dtermite activity was less significant (r**2 between 0.48 and 0.83). Frequency of attack as measured by percent of bait rolls "hit" were not different among sites indicating no differences in densities of subterranean termites. Degradation of Chihuahuan Desert grasslands and associated vegetation change has had minimal effect on the activity of subterranean termites. Subterranean termites continue to affect soil properties and processes in both degraded (desertified) and undesertified ecosystems.