This work examines the long-term ecological legacies of land use intensity in two different ecosystem types of the southwestern US, which supported agroecologically active and well-studied populations of humans until 1200- 1400 AD. This unique perspective, accessible only through the archaeological record, provides an understanding of the importance of humans and their varied land use activities as drivers of persistent ecological patterns and processes. Data were collected across a gradient of known prehistoric human activity in arid and semi-arid ecosystems of central Arizona that represent two ends of a spectrum of human occupation in population and duration. Cave Creek, located in the Sonoran desert of the northern Phoenix basin, supported relatively large human populations for approximately four centuries using both irrigated and dry land farming techniques. Perry Mesa is located at higher elevation in the semi-arid desert grasslands of Agua Fria National Monument. Populations at Perry Mesa were smaller and more ephemeral than at Cave Creek, and were supported by only dry land agricultural fields and house gardens. In each system, the importance of land use intensity on modern ecological properties and processes is evaluated by comparing areas of high intensity use (irrigated fields at Cave Creek, rain-fed terraces at Perry Mesa) with areas of relative low use (rain-fed terraces at Cave Creek, house gardens at Perry Mesa) and nearby areas where there is no archaeological evidence of human land use (off-site controls).