Long-term monitoring is at the core of CAP LTER’s research program. It enables CAP scientists to examine changes over time, particularly in ecological variables that are slow cycling. In the rapidly growing Phoenix metropolitan region, long-term monitoring also allows scientists to monitor changes as urbanization takes place in urban fringe areas and as density increases in already urbanized areas.
CAP has a large suite of long-term monitoring efforts, ranging from point count bird censuses, which are conducted semi-annually, to the Phoenix Area Social Survey (PASS), which is conducted every five years. Survey 200 is the flagship of CAP’s long-term monitoring efforts and has spawned a number of analyses examining plant diversity, soil chemistry, and trophic structure.
|
Monitoring Program |
Number of Sampling Locations |
Sampling Frequency |
Variables Measured |
| Arthropods | 31 sites | Quarterly | Ground-dwelling arthropods |
| Birds | 56 core sites | Semiannually (Jan, Mar) | Point-count bird census |
| Birds | 40 PASS neighborhoods | Semiannually (Dec, Feb) in each of two years following the PASS survey (see below) | Point-count bird census |
| Tree survey | 50 sites | Annually (winter) | Tree biovolume
Tree condition |
| Survey 200 | 204 sites | Five years (spring) | Photo documentation
Vegetation composition Vegetation cover Soil: physical, chemical and biological Habitat/built structure Human activity |
| North Desert Village | 4 treatment areas | Continuous | Air temperature
Ground surface temperature Soil temperature Soil heat flux Soil water content |
| North Desert Village | 4 treatment areas | Monthly | Landscape water use
Electricity use Dwelling surface temperature |
| North Desert Village | 4 treatment areas | Annually, with exception of bird and arthropod monitoring (as above) | Birds
Arthropods Primary productivity |
| Atmospheric deposition | 15 locations (upwind, core, and downwind of greater Phoenix) | Quarterly | Wet & dry nitrogen deposition |
| Desert flora productivity | 15 locations (upwind, core, and downwind of greater Phoenix) | Semiannually (spring and fall) | Productivity (stem length growth) of Creosote (Larrea tridentata)
Productivity (biomass harvesting) of annual plants |
| Desert soil chemistry | 15 locations (upwind, core, and downwind of greater Phoenix) | Semiannually (spring and fall) | Nutrients, and major cations and anions |
| Water-quality monitoring | 5 locations at major influent (Salt and Verde Rivers, CAP canal) and effluent (Salt and Gila Rivers) systems | Bimonthly | Nutrients
Major cations/anions pH Temperature Specific conductance Particulates |
| Groundwater-quality monitoring | Single experimental plot along Gila River | Bimonthly | Water quality |
| Stormwater monitoring | Single location at outflow of Indian Bend Wash | Flow-weighted sampling of each runoff-producing storm | Water quality |
| Land-use and land-cover | CAP LTER site | Every five years | Land use change
Land cover change |
| Microclimate | AZMet stations | Data mined as needed | Growth and intensity of urban heat island
Decline in frosts and freezes |
| Microclimate | 2 locations corresponding to atmospheric deposition study sites | Continuous | Standard suite of meteorological variables |
| Phoenix Area Social Survey (PASS) | 40 neighborhoods | Five years | Water supply and conservation
Land use, preservation and growth management Air quality and transportation Climate change and the urban heat island |