Landscape Analysis and Climate Change

Climate, Forests and Woodlands May 16, 2011

1 Adapted from: Kennedy, Rebecca S.H. 2008. Landscape Analysis and Climate Change. (May 20, 2008). U.S. Department of Agriculture, Forest Service, Climate Change Resource Center. http://www.fs.fed.us/ccrc/topics/landscape-analysis.shtml
2 Issue
3 Expected Changes
4 Considerations for Management

Adapted from: Kennedy, Rebecca S.H. 2008. Landscape Analysis and Climate Change. (May 20, 2008). U.S. Department of Agriculture, Forest Service, Climate Change Resource Center. http://www.fs.fed.us/ccrc/topics/landscape-analysis.shtml

Issue

Landscape analysis involves the assessment of features of a landscape in relation to any of a group of factors such as land use change; shifts in hydrology, forest harvest, or other disturbance; topography; historical vegetation conditions; past and potential future climate change; and other factors. A landscape may be considered as an area larger than a forest stand and smaller than a region, but for practical purposes in forest management, a landscape is a level of analysis that may be of any size, depending on the question of interest. As such, the scope of landscape analysis may encompass multiple disciplines, but the questions asked are typically at a scale that is relevant to forest management and planning. The key issue is that landscape analysis must incorporate climate change if it is to accurately represent potential future conditions in landscapes.

Landscapes bridge the gap between stands with microclimate and regions with macroclimate. The scaling of climate and its potential effects on vegetation and other landscape elements is a key problem in current landscape analysis research. Landscape analysis involves the evaluation of vegetation patterns and linkage of patterns to underlying processes as well as the interaction of pattern and process (such as vegetation patterns versus fire and climate processes). How might vegetation communities change in areas of high topographic relief in the western United States, where the influences of macro- and microclimate may be complex and potentially contradictory? How might climate change, vegetation, and disturbances such as fire, forest management, insects, disease and invasive species, interact over time to modify landscape patterns of vegetation, carbon sequestration, and biodiversity?

Expected Changes

Projected climate change will probably have direct effects on site productivity and biogeography and indirect effects on vegetation through changes in fire, insect, and disease disturbances (Carroll et al. 2003, Dale et al. 2001, Parry et al. 2007). For example, the distribution of cool coniferous forests (e.g., Pacific silver fir, Abies amabilis) in the western Cascade Range may shrink, whereas dry mixed-conifer forests dominated by ponderosa pine may expand (Shafer et al. 2001).

Figure 1. The area burned by wildfires in the western United States is likely to increase as the climate becomes warmer. Source: USDA Forest Service.

Wildfire frequency and duration in landscapes of the western United States have increased since the mid-1980s, resulting from subregional responses to changes in climate. The Northern Rockies have seen the greatest increases, followed by the Sierra Nevada, southern Cascade Range, and northern California and southern Oregon coast ranges (Westerling et al. 2006). In northern California, land use changes may also be involved. The Intergovernmental Panel on Climate Change’s projected warming (1.5 to 5.8°C by the end of the 21st century) is far greater than that observed (0.9°C) in recent decades in the West. These conditions compound the increased fire risk resulting from fire suppression and resulting fuel buildup during the 20th century (Keeton et al. 2007).

It should be noted that model results reflect the current status of our knowledge about a topic. Parameters are typically set and input data are prepared based on a combination of the best scientific information available and the modeling environment (e.g., technical constraints). As information increases about both the ecological systems and the pertinent elements of climate change, so will our ability to more precisely and accurately estimate projected changes to forested landscapes. Given that, the climate changes listed below are likely and relevant to landscapes of the western United States.

Variability in fire regimes in California is projected to increase as interspersed wet and dry years lead to a cycle of wetter years, promoting more biomass growth, which leads to more and higher severity fires during dry years (Lenihan et al. 2003).
Climate change appears to cause major shifts in landscape vegetation dynamics, which is exacerbated if fire regimes change independently of biophysical conditions. This scenario was established by simulating potential future landscape conditions and assessing the departure of simulated future landscape composition from reference conditions (Keane et al. 2008).
The area burned in wildfires is expected to increase under both warmer/wetter and warmer/drier climate change scenarios (3.6°C added to maximum and minimum daily temperatures, daily rainfall amount multiplied by 1.2 [wetter] or 0.8 [drier]), with a larger increase in area burned under the warmer/drier scenario, according to a set of landscape fire succession models applied to a simulation landscape (Cary et al. 2006).
In the western United States and at the continental scale (1 km), long-term satellite data show consistently earlier onsets of spring greening and corresponding increases in length of growing season (Schwartz et al. 2002). Wildfire responses to an earlier spring differ across the West and by elevation, with the northern Rockies and northern California being the most vulnerable, and with higher elevations buffered somewhat from the effects of increased temperature by the relatively short dry season and the available moisture at those elevations (Westerling et al. 2006).

Considerations for Management

Increased disturbance and other surprises are likely. Behaviors that lead to ecosystem resilience may be more likely to achieve management objectives.

Variability in the response of attributes within and among landscapes is likely, while individuality of place may be highly relevant to local ecosystem response. Responses to climate change are likely to differ locally depending on a variety of environmental and other factors. Generalizations about response could easily be erroneous because of local conditions.

Landscapes are dynamic and the range of conditions over time in one place in the landscape or across the landscape at one time may vary. Managers may build resiliency if they do not apply the same approach everywhere. Likewise, building redundancy into the system, which may involve increasing the total area of critical habitat to mitigate disturbance effects on biodiversity, may also be of key importance as disturbance-climate change interactions are projected.

Adapted by: Melanie Lenart, University of Arizona.

References Cited
Carroll, A.L., S.W. Taylor, J. Régnière, and L. Safranyik. 2003. Effects of climate change on range expansion by the mountain pine beetle in British Columbia. In: T.L. Shore, J.E. Brooks, J.E. Stone, eds., Mountain pine beetle Symposium: Challenges and solutions. Information Report BC-X-399. Victoria, B.C., Canada. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre: 223-232.

Cary, G.J., R.E. Keane, R.H. Gardner, S. Lavorel, M.D. Flannigan, I.D. Davies, C. Li, J.M. Lenihan, T.S. Rupp, and F. Mouillot. 2006. Comparison of the sensitivity of landscape fire-succession models to variation in terrain, fuel pattern, climate, and weather. Landscape Ecology 21: 121-137.

Dale, V.H., L.A. Joyce, S. McNulty, R.P. Neilson, M.P. Ayres, M.D. Flannigan, P.J. Hanson, L.C. Irland, A.E. Lugo, C.J. Peterson, D. Simberloff, F.J. Swanson, B.J. Stocks, and B.M. Wotton. 2001. Climate change and forest disturbances. BioScience 51: 723-734.

Keane, R.E., L.M. Holsinger, R.A. Parsons, and K. Gray. 2008. Climate change effects on historical range and variability of two large landscapes in western Montana, USA. Forest Ecology and Management 254: 375-389.

Keeton, W.S., P.A. Mote, and J.F. Franklin. 2007. Climate variability, climate change, and western wildfire with implications for the urban-wildland interface. In: A. Troy and R.G. Kennedy, eds., Living on the edge: Economic, institutional and management perspectives on wildfire hazard in the urban interface. Advances in the economics of environmental resources. Oxford, United Kingdom: Elsevier Science JAI Press: 225-253. Vol. 6. Chapter 13.

Lenihan, J.M., R.J. Drapek, D. Bachelet, and R.P. Neilson. 2003. Climate change effects on vegetation distribution, carbon, and fire in California. Ecological Applications 13: 1667-1681.

Parry, M.L., O.F. Canziani, J.P. Palutikof, P.J. van der Linden, and C.E. Hanson, eds. 2007. Climate change 2007: impacts, adaptation and vulnerability. Contribution of Working Group II to the fourth assessment report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom: Cambridge University Press. 976 pp.

Schwartz, M.D., B.C. Reed, and M.A White. 2002. Assessing satellite-derived start-of-season measures in the conterminous USA. International Journal of Climatology 22: 1793-1805.

Shafer, S.L., P.J. Bartlein, and R.S. Thompson. 2001. Potential changes in the distributions of western North America tree and shrub taxa under future climate scenarios. Ecosystems 4: 200-215.

Westerling, A.L., H.G. Hidalgo, D.R. Cayan, and T.W. Swetnam. 2006. Warming and earlier spring increase Western United States forest wildfire activity. Science 313: 940-943.

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