One of the central organizational themes for NEON relates to ecosystem services, and the dynamics of the primary ecological drivers that influence the status of these crucial life-supporting services. These ecological drivers are among the "grand challenges" identified by the National Research Council as research topics that are central to providing the environmental knowledge needed by the next generation to achieve sustainability. Below we discuss four of these ecological drivers in relation to the Beaver Creek Watershed proposed core site.

Climate Change
"The challenge is to increase our ability to predict climate variations, from extreme events to decadal time scales; to understand how this variability may change in the future; and to assess realistically the resulting impacts."

        The Beaver Creek Watershed (BCW) is an ideal location to monitor the ecological impacts of climate-change because of its pronounced elevation gradient and its geographic location within the region. Elevation gradients, such as the one found in the BCW, are sensitive sentinels for detecting the differential effects climate-change. The BCW is located near the northern extent of monsoonal precipitation, and thus, in combination with other sites inside and outside of Domain 13, would contribute to NEON's ability to detect and document such climate-change impacts.

Land Use
"The challenge is to develop a systematic understanding of changes in land uses and land covers that are critical to ecosystem functioning and services and human welfare."

        The Beaver Creek Watershed reflects Domain 13 in that it is predominantly managed by federal agencies (USFS and the NPS). The BCW contains lands that are managed for a diversity of activities and values, from various types of recreation and grazing, to residential housing and areas managed for their wilderness values. Beaver Creek is a major drainage into the Verde River, which then flows into the Salt River, providing water to the expanding Phoenix metropolitan region, the fastest growing urban area in the USA. Extensive areas in the BCW are managed specifically for watershed research and wildlife habitat characteristics. There is a full spectrum of stand structures within the ponderosa and pinyon-juniper vegetation types in the watershed, which would be available to expand studies to compare ecological consequences of different stand structures.

Invasive Species
"The challenge is to understand species invasion as an ecological process sufficiently to allow forecasting of the invasiveness of species and prediction of which potential biological agents would both be effective in controlling an exotic species and have the fewest detrimental effects on natural and managed ecosystems."

        Invasive plants can negatively affect soil productivity, limit plant diversity, and reduce the acreage of natural grazing lands. Invasive animals can carry and spread diseases for which native animals have no resistance. Invasive species often compete with native species for food, water, and space. Invasive species not only disrupt habitats and populations impacting ecosystem composition, but they can also potentially disrupt important ecosystem functions. We have catalogued 58 invasive species in the Beaver Creek Watershed. While often the cause of unfortunate ecological problems, the presence of these species provides opportunities to study. For instance, exotic fishes and crayfish provide a challenge to restoring the perennial Wet Beaver Creek.

Hydroecology
"The challenge is to develop an improved understanding of and ability to predict changes in freshwater resources and the environment caused by floods, droughts, sedimentation, and contamination."

        The Beaver Creek Watershed is an outstanding area for conducting aquatic studies in Domain 13 because it has the representative hydrology, water issues, and because it has been designated as an experimental watershed and UNESCO Man and the Biosphere reserve to specifically address water-related issues. Extensive research has been conducted in the BCW's sub-watersheds to study the effects various vegetation treatments have on streamflow, erosion and sedimentation, vegetation, and wildlife. This research was accompanied by climate monitoring, providing a wealth of climate-related legacy data. The BCW typifies southwestern U.S. hydrological system, with both perennial and intermittent reaches, drought-flood cycles, and hydraulically connected surface and groundwater.