Project overview

Protected lands, such as the McDowell Sonoran Preserve (hereafter referred to as the Preserve) in Scottsdale, Arizona, provide critical refuge for native biota and natural, ecological processes within and near urban environments. At the same time, a key feature that makes urban, open-space preserves so valuable − their proximity to urban areas − places strain on the ecological integrity of these systems through visitation, habitat fragmentation, and the introduction of exotic species among others. Effective management of these systems requires detailed knowledge of the biota within the protected area, and monitoring of ecological indicators through time. Arthropods are well suited to monitoring ecological health. This diverse group of organisms typically reflects overall biological diversity of a system, and includes several trophic levels; their short generation times mean they will likely respond quickly to change; and they are relatively easy to sample. As part of a broad effort by the McDowell Sonoran Conservancy Field Institute, an organization that oversees science and research in Preserve, to establish a baseline inventory of biota in the Preserve, investigators with the Central Arizona−Phoenix Long-Term Ecological Research (CAP LTER) program at Arizona State University (ASU) in collaboration with Field Institute Citizen Scientists are monitoring ground-dwelling arthropods at select locations that reflect a diversity of habitat within the Preserve. Investigators employ a sampling design that is intended to provide insight regarding influence of the urban-wildland interface on the arthropod community within the protected area. The simple but effective technique of pitfall trapping is used to sample ground-dwelling arthropods at select locations spanning a wide range of habitat with the Preserve. Additional collections of vegetation-dwelling arthropods have been conducted at the sampling locations at periodic intervals.

Project design and sampling

Pitfall trap transect locations include five groups of paired transects that span a large range of the north-south and east-west axes of the Preserve, and include numerous unique vegetation communities. Four transect pairs are positioned such that one transect is within 100 m of the Preserve boundary and existing development, and the second transect at least 0.5 km from the Preserve boundary-development. A fifth paired transect treated as a control is located in a similar fashion but at a location where there is not currently development near the Preserve boundary (Dixie Mine and Prospector sites). Transect locations were selected specifically to include relatively similar geomorphological characteristics, including elevation (610-914 m), slope (≤ 20%), and aspect (0-270°, 315-360°) to minimize extraneous factors. All transects are positioned within 75 m of existing trails to facilitate access and limit off-trail travel while keeping traps out of public view. Sampling is conducted quarterly in keeping with CAP LTER protocols and concomitant sampling at other Valley location.