Interactive Effects of Climate Change and Fire on Bird Communities: Landscape and Regional Projections

Duration:  March 1999 - January 2004

The Chihuahuan Desert is the largest of North America's deserts. The majority of this desert lies within Mexico, but its northern boundary extends into Arizona, New Mexico, and the Trans-Pecos Region of Texas. The vegetation of the Chihuahuan Desert is a mosaic of riparian, desert grassland, and desert shrub plant communities.  The distribution and species composition of these communities are strongly influenced by precipitation and fire.

Global climate change is expected to affect terrestrial systems by altering the intensity, frequency, and duration of disturbance events.  It is predicted that arid and semiarid systems, like those of the Trans-Pecos Region, will experience increases in temperature, changes in the frequency of rainfall events, and increases in the frequency of natural wildfires.  Because rainfall and fire are driving forces in arid and semiarid systems, changes in the frequency or intensity of rainfall events and fire may potentially alter the species composition and structure of plant communities and thus may have an impact on their associated bird communities.

To assess the vulnerability of the Trans-Pecos Region to climate change and increased fire frequency, and to develop effective management and restoration practices to accommodate such changes, data are needed in several areas.

Most importantly, we need the ability to predict the interactive effects of climate change and increased fire frequency on the Region's habitat types and the birds they support.  Predictions of how birds will respond to such changes at landscape and regional scales will be essential for anticipating and countering environmental impacts.  Effects of mitigation efforts, such as fire management, also need to be assessed. 

To meet these needs, three information requirements must be satisfied: 

• First, we need to understand bird species distribution patterns in the Trans-Pecos Region.  Data on species composition, relative abundance, and habitat relations would provide managers with baseline data for establishing monitoring programs and setting management goals for priority species.
• Second, we need to know the geographic distribution and extent of major habitats (riparian vegetation, grassland, shrubland, yucca-ocotillo and montane forest) in this region.
• Third, we need to understand ecological relations between bird species and land-cover types across spatial and temporal scales.

We will use a combined field and simulation-modeling effort to accomplish the following project objectives:

• Develop a Geographic Information System (GIS) land-cover map for Big Bend National Park and the Trans-Pecos Region.
• Develop statistical models that predict numbers of birds from landscape-scale vegetation variables.
• Use a simulation model to predict spatial and temporal dynamics of vegetation associated with climate change and subsequent feedbacks on fire frequency and intensity.
• Incorporate bird-landscape models into the vegetation simulation model to project how numbers of birds will be influenced by climate-induced and fire-induced vegetation changes.
• Use this overall simulation model to assess effects of various climate-change scenarios and fire frequency scenarios on the capacity of the Trans-Pecos Region to support bird communities.

Application of Results:

Our simulations will enable us to provide resource managers with information on potential global-change impacts and how effective fire management efforts are likely to be in ameliorating or reversing these impacts.

Products:

Expected products include:

1. GIS landcover maps for Big Bend National Park and the Trans-Pecos Region
2. Projections of the effects of increased fire frequency and climate change on Chihuahuan Desert vegetation
3. Estimates of the capacities of the landscape and region to support associated bird communities under different model scenarios
4. Information on management options that would effectively ameliorate global-change impacts
5. Annual and final technical reports of research results, and publications in peer-reviewed journals

	Primary Contact:  Dr. Wylie C. Barrow, Jr., USGS National Wetlands Research Center E-mail Dr. Barrow