Patterns of wetland availability and land use practice are examined within keystone migratory bird habitats in the Pacific flyway (southern Oregon and northeastern California). The results provide decision support for conservation partners to evaluate wetland and land use benefits through an increased understanding of annual resource availability and water use practices. Products inform and refine targeting and evaluation of conservation actions (i.e., enhancement, restoration, or protection) in these dynamic wetland landscapes that structure migratory bird abundance and drive rural agricultural economies.
Spatiotemporal dynamics in wetland productivity are modeled from freely available Landsat imagery. Satellite indices correlated to net primary production, soil moisture, and open water extent are measured over a 31-year span (1984–2015) to account for annual climatic variability. Images are acquired from early spring through fall at 16-day intervals to measure seasonal changes in wetland condition. Results of this analysis are then used to identify bottlenecks in seasonal resource availability potentially affecting life cycle needs of migratory birds and other wetland associated species. Public and private land contribution to resource availability are estimated by evaluating patterns of land tenure influenced through annual and seasonal shifts in wetland condition.
Seasonal wetland dynamic example in working (flood-irrigated hay meadow) wetlands. Hydrograph (surface water) and spectral response curve (primary productivity) illustrate seasonal variability in wetland condition derived from satellite data. Patterns depicted are similar to hydrologic and vegetative processes occurring in related unmanaged wetland systems. Dark areas are representative of open water. Red color and intensity (normalized difference vegetation index; range 1 to –1) are indications of high vegetative productivity and mesic soil condition. The April 16 image captures surface water extent associated with flood irrigation and spring runoff. The June 19 image illustrates surface water reduction and increased productivity of emergent vegetation typical of temporary wetland patterns. The August 23 image shows little change in surface water extent but indicates a reduction in productivity likely associated with haying and grazing activities. The sharp drop in primary productivity in early July is correlated to the timing of hay cutting practices, which occur near this date in many regions of the Intermountain West. North is oriented toward the top of the image.