PARENT SESSION
Oral Session #37: River and Riparian Restoration II.
Presiding: J. Berg
Tuesday, August 6. 1:00 PM to 4:00 PM. Mohave Meeting Room, TCC.
Ground arthropods as indicators of flooding regime and riparian restoration along the middle Rio Grande.
MOLLES, MANUEL*,1, CARTRON, JEAN-LUC1, SCHUETZ, JENNIFER1, CRAWFORD, CLIFFORD1, DAHM, CLIFFORD1, 1 University of New Mexico, Albququerque, NM
ABSTRACT- Experimental flooding along the middle Rio Grande in central New Mexico indicated that flooding substantially influences the structure of riparian ground arthropod assemblages and suggested that ground arthropods may be useful as indicators of riparian forest restoration. The present study was designed to determine whether those earlier site-intensive results could be scaled up to a 160km section of the middle Rio Grande riparian corridor. In April, June, August, and September 2001, we pit trapped arthropods at eight riparian forest sites, four characterized by seasonal flooding (flood sites) and four where seasonal flooding no longer occurs (non-flood sites). Carabid beetle species richness and abundance were significantly (P = 0.02 and P = 0.03, respectively) higher at flood sites. Despite a significant (P = 0.05) decrease in Armadillidium vulgare numbers following flooding, overall, flood sites were characterized by higher numbers of this isopod (P = 0.05). Binomial logistic regressions, using total abundance of carabid beetles, successfully differentiated all flood sites from all non-flood sites. Successful classification of sites was also possible using abundances of four (67%) out of six possible pairwise combinations of carabid species. Numbers of Gryllus alogus (Orthoptera, Gryllidae) and Porcellio laevis (Isopoda) combined with those of A. vulgare likewise successfully differentiated flood sites from non-flood sites. Overall, our results indicate that abundance and species richness of ground arthropods, especially carabid beetles, are good indicators of degree of hydrologic connectivity between the Rio Grande and its riparian forests. Relative homogeneity of ground arthropod assemblages at non-flood sites suggests that absence of regular flooding strongly influences arthropod community structure. Meanwhile, differences in numbers and species composition of ground arthropods at flood sites may reflect variation in the specific nature of the hydrological connection between these sites and the river.
KEY WORDS: riparian, restoration, arthropod, indicators