David D. Breshears School of Natural Resources Institute for the Study of Planet Earth and Department of Ecology & Evolutionary Biology The University of Arizona Tucson AZ 85721-0043 daveb@email.arizona.edu
The Santa Rita Experimental Range (SRR), a historical UNIVERSITY OF ARIZONA (UA) research site ~50 km south of Tucson with a 100+ year legacy of research, is proposed as the Desert Southwest (DSW) Domain Core Wildland Site. The SRR is well-suited to represent the domain and address NEON hypotheses by virtue of its: i) geographic location (51892 acres centered on 31.8325, -110.8742)- mid-way within the domain and south of the rapidly developing Phoenix-Tucson Megapolitan; ii) precipitation regime (Sonoran) - intermediate in seasonality of DSW rainfall between winter-dominated in the west (Mojave) to summer-dominated in east (Chihuahuan); iii) dominant vegetation - characterized by Desertscrub and Grassland, which together represent ~ 90 % of the Domain, and spaning much of a ‘Sky Island’ gradient that extends from riparian/desert floor to coniferous forest; iv) contrasting landforms - representative bajada gradients at SRR are well-suited for flux towers; juxtaposition of early Pleistocene- to Holocene-aged geomorphic surfaces; v) land use - contrasting livestock grazing histories (including ungrazed lands), dating to 1902, which are representative of the pervasive land use in DSW wildlands; and vi) invasive species history - native desert shrubs and non-native grasses have a well-documented history of increase ; opportunities exist to compare invaded and non-invaded areas.
Scientists at SRR and nearby partner sites (e.g., Desert Laboratory), have been integrally involved in the development of theoretical ecology, including pioneering contributions in succession (Clements), biogeography (Whittaker), and arid zone physiological ecology (F. Shreve, Cannon, McGinnies), that formed the basis for defining North American Deserts, elucidating plant-climate relationships, developing the field of rangeland management, and establishing the Ecological Society of America. This foundation was the basis for modern process studies of: i) ecological responses to precipitation pulses, ii) biophysical scaling relationships, iii) woody-herbaceous plant interactions, iv) life zone shifts, and v) wind vs. water erosion. These advances have drawn on long-term data sets including i) 100+ years of documented land use/vegetation change at SRR, ii) > 100+ years plant population tracking at nearby Tumamoc Hill, iii) classic baseline data sets developed along a sky island elevational gradient, and iv) studies from the longest-instrumented watershed in the USA at Walnut Gulch.
UA has a long, successful record managing large science projects (Steward Observatory, the National Optical Astronomy Observatory, Phoenix Mission to Mars); and environmental programs including SAHRA (NSF Science and Technology Center Semi-Arid Hydrology and Riparian Areas), the US National Phenology Network, Institute for the Study of Planet Earth, Arizona Water Institute, and the Water Resources Research Center and major outreach efforts via its Cooperative Extension Program and partnerships with the Arizona Sonoran Desert Museum. UA President Robert Shelton enthusiastically supports the NEON initiative and UA participation. SRR meets all criteria for a core site (e.g., year-round accessibility, 30+ year commitment, cyberinfrastructure, site security). It also leverages numerous NEON-relevant resources, including SECA (Semiarid Ecohydrology Array, a developing network of 10+ distributed flux towers) and potentially >$35M in matching resources through the acquisition of the Biosphere 2 (to be expanded to compliment SRR research) that includes cyberinfrastructre, on-site laboratories, lodging, conference, meeting and educational facilities that are unparalleled in the Domain. A prototype expertise database covering the DSW Domain has been developed covering ~ 20 institutions and ~ 500 NEON-relevant researchers to date; and can serve as a cyberinfrastructure catalyst for domain coordination once activated.