Overview & Applicability
The Climate Change Atlases can help to answer a range of questions concerning current and projected suitable habitat (year 2100) for 134 tree species and 147 bird species in the eastern U.S.
For each species included in the Atlases, information is provided on species characteristics, life history and current distribution. Users can see which factors (e.g. temperature, elevation, soil type) help to drive species distributions, offering some guidance on species sensitivity to large-scale climate differences. The Atlases supply maps and summary numerical data that show how each species' suitable habitat is projected to change under three different climate models, for both high and low emissions scenarios. Maps can be viewed via the Atlas online interface, or with the program Google Earth.
For certain pre-defined areas, the Atlases also present data on how the overall grouping of species habitats within that area might change under future climates. Currently, projections are provided for each state and geographic region (birds and trees) and for each national forests/grassland, national park and ecoregion (trees only).
Researchers at the Northern Research Station (NRS) first developed a statistical model in 1996 to assess potential changes in habitat for common tree species in the eastern United States. Since then, the model has gone through several improvements, leading to the development of the DISTRIB model which is the basis for the Tree and Bird Atlases. A new online version of the Atlas was released in 2014, and includes descriptions of tree characteristics that affect their adaptability to climate change. See the Atlas publications page for a list of documents related to the development and use of this model.
Inputs and Output
The model inputs are pre-defined by the researchers, so no user-collected data is required. For the Tree Atlas, these defined inputs include data on current tree species distributions from the Forest Inventory and Analysis (FIA) program, as well as datasets that fall under four main categories: climate, elevation, soil characteristics, and land use. A full list of model inputs can be found on the Tree Atlas page. For the Bird Atlas, inputs include data on current bird distribution from the Breeding Bird Survey as well as data on climate, elevation, and tree species distributions. See the Bird Atlas for a full list of inputs.
Tool outputs primarily include spatial and numerical representations of current and future suitable species habitat. Measurements of suitable habitat distribution and change are given in importance value (trees) and incidence (birds). Importance value is a measure of abundance that accounts for both tree basal area and number of stems, ranging from 0 - 100. Incidence is calculated from the number of years (from 1981-1990) that a species was observed on the Breeding Bird Survey routes selected by the USGS. Incidence value ranges from 0 to 1.
Restrictions and limitations
The Atlases should be used at an appropriate scale; analyses are done at the level of 20x20 km cells, so fine scale interpretations may be inappropriate. It is also important to note that there are several uncertainties inherent in this type of species distribution model. For example, there is a considerable range in projected future climate conditions depending on which climate model is used and which emissions scenario is chosen to represent future conditions. The Atlas deals with this by providing projected suitable habitats for a range of different climate models and emissions scenarios.
In addition, the model predicts suitable habitat better for some species than for others. A reliability index is included in the Atlases to reflect this. The reliability scores are based on the statistical techniques used to create the model, but basically take into account how good the predictor variables are at describing where species are located. Projections for species with low reliability scores should be interpreted with caution.
Finally, the model is only predicting where suitable species habitat may be in the future. It cannot predict where species themselves will be located, since that depends on factors such as species migrations, land use changes, biological factors (e.g. regeneration, dispersal, competition) and disturbances (e.g . fire, insects, pollution), all of which are difficult to quantify. Researchers are currently working on both quantitative and qualitative tools that help to account for some of these uncertainties.
To see a full list of strengths and limitations for the DISTRIB model used in the Atlas, please see this list.
Accessing the tool and additional information
Please see the NRS Atlas homepage to use the Atlases, to view tutorials on how to use the Atlases, and for additional resources: http://www.fs.fed.us/nrs/atlas/.
Publications relevant to the Climate Change Atlases are available online for both Trees and Birds.
Tree Atlas citation:
Landscape Change Research Group. 2014. Climate change atlas. Northern Research Station, U.S. Forest Service, Delaware, OH. http://www.nrs.fs.fed.us/atlas.
It is also recommended that the following publications be cited along with the atlas citation, depending on what you used:
For habitat suitability models on trees:
Iverson, L. R., A. M. Prasad, S. N. Matthews, and M. Peters. 2008. Estimating potential habitat for 134 eastern US tree species under six climate scenarios. Forest Ecology and Management 254:390-406. http://www.treesearch.fs.fed.us/pubs/13412
For Modification Factors/Adaptability of tree species:
Matthews, S. N., L. R. Iverson, A. M. Prasad, M. P. Peters, and P. G. Rodewald. 2011. Modifying climate change habitat models using tree species-specific assessments of model uncertainty and life history factors. Forest Ecology and Management 262:1460-1472. http://treesearch.fs.fed.us/pubs/38643
For habitat suitability models on birds:
Matthews, S. N., L. R. Iverson, A. M. Prasad, and M. P. Peters. 2011. Potential habitat changes of 147 North American bird species to redistribution of vegetation and climate following predicted climate change. Ecography 260:1460-1472. http://treesearch.fs.fed.us/pubs/39841