Mary E. Manning

A range-wide restoration strategy for whitebark pine (Pinus albicaulis)

Whitebark pine (Pinus albicaulis), an important component of western high-elevation forests, has been declining in both the United States and Canada since the early Twentieth Century from the combined effects of mountain pine beetle (Dendroctonus ponderosae) outbreaks, fire exclusion policies, and the spread of the exotic disease white pine blister rust (caused by the pathogen Cronartium ribicola). The pine is now a candidate species for listing under the Endangered Species Act. Within the last decade, with major surges of pine beetle and increasing damage and mortality from blister rust, the cumulative whitebark pine losses have altered high-elevation community composition and ecosystem processes in many regions. Whitebark pine is a keystone species because of its various roles in supporting community diversity and a foundation species for its roles in promoting community development and stability. Since more than 90 percent of whitebark pine forests occur on public lands in the United States and Canada, maintaining whitebark pine communities requires a coordinated and trans-boundary effort across Federal and provincial land management agencies to develop a comprehensive strategy for restoration of this declining ecosystem. We outline a range-wide strategy for maintaining whitebark pine populations in high mountain areas based on the most current knowledge of the efficacy of techniques and differences in their application across communities. The strategy is written as a general guide for planning, designing, implementing, and evaluating fine-scale restoration activities for whitebark pine by public land management agencies, and to encourage agency and inter-agency coordination for greater efficiency. The strategy is organized into six scales of implementation, and each scale is described by assessment factors, restoration techniques, management concerns, and examples.

Effects of Climate Change on Ecological Disturbance in the Northern Rockies

Disturbances alter ecosystem, community, or population structures and change elements of the biological and/or physical environment. Climate changes can alter the timing, magnitude, frequency, and duration of disturbance events, as well as the interactions of disturbances on a landscape, and climate change may already be affecting disturbance events and regimes. Interactions among disturbance regimes, such as the co-occurrence in space and time of bark beetle outbreaks and wildfires, can result in highly visible, rapidly occurring, and persistent changes in landscape composition and structure. Understanding how altered disturbance patterns and multiple disturbance interactions might result in novel and emergent landscape behaviors is critical for addressing climate change impacts and for designing land management strategies that are appropriate for future climates. This chapter describes the ecology of important disturbance regimes in the Northern Rockies region, and potential shifts in these regimes as a consequence of observed and projected climate change. We summarize five disturbance types present in the Northern Rockies that are sensitive to a changing climate—wildfires, bark beetles, white pine blister rust (Cronartium ribicola), other forest diseases, and nonnative plant invasions—and provide information that can help managers anticipate how, when, where, and why climate changes may alter the characteristics of disturbance regimes.

Effects of Climate Change on Rangeland Vegetation in the Northern Rockies

A longer growing season with climate change is expected to increase net primary productivity of many rangeland types, especially those dominated by grasses, although responses will depend on local climate and soil conditions. Elevated atmospheric carbon dioxide may increase water use efficiency and productivity of some species. In many cases, increasing wildfire frequency and extent will be damaging for big sagebrush and other shrub species that are readily killed by fire. The widespread occurrence of cheatgrass and other nonnatives facilitates frequent fire through annual fuel accumulation. Shrub species that sprout following fire may be quite resilient to increased disturbance, but may be outcompeted by more drought tolerant species over time.

Effects of Climate Change on Forest Vegetation in the Northern Rockies

Increasing air temperature, through its influence on soil moisture, is expected to cause gradual changes in the abundance and distribution of tree, shrub, and grass species throughout the Northern Rockies, with drought tolerant species becoming more competitive. The earliest changes will be at ecotones between lifeforms (e.g., upper and lower treelines). Ecological disturbance, including wildfire and insect outbreaks, will be the primary facilitator of vegetation change, and future forest landscapes may be dominated by younger age classes and smaller trees. High-elevation forests will be especially vulnerable if disturbance frequency increases significantly. Increased abundance and distribution of non-native plant species, as well as the legacy of past land uses, create additional stress for regeneration of native forest species.