Long-term monitoring of ground-dwelling arthropods in the McDowell Sonoran Preserve, Scottsdale, Arizona, ongoing since 2012

*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 Conservance
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.