Shallow
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
- Transition T1A More details
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
The Reference State is a description of this ecological site just prior to Euro-American settlement but long after the arrival of Native Americans. At the time of European colonization, what would have been observed on these sites would have primarily depended on the time elapsed since the last wildfire occurred. Had the site been relatively undisturbed (i.e. without fire) for approximately 400 years or longer, the late seral climax of Subalpine fir and Engelmann spruce co-dominate forest would have been found (1.1). The understory would have been relatively sparse due to tree competition, overstory shading, and duff accumulation. Wildfire (1.1a) would have replaced these stands with diverse herb-dominated vegetation (1.2). In the absence of any major disturbance (1.2a, 1.3a, 1.4a, 1.5a), the vegetation would have progressed into more of a shrub-herb co-dominance (1.3), followed by aspen (Populus tremuloides) and possibly lodgepole pine (Pinus contorta) (1.4), then would have become a mature stand of subalpine fir (Abies lasiocarpa) (1.5). Ultimately the site would have been reinvaded by Engelmann spruce (1.1). Wildfire (1.1a, 1.5b) would have been the primary disturbance factor prior to colonization. Livestock grazing and fire exclusion can accelerate natural succession of woody species.
Submodel
States 1, 5 and 2 (additional transitions)
1.1. Mature Engelman Spruce - Subalpine Fir
1.5. Mixed Age Subalpine Fir
1.2. Herb-Dominated Meadow
Description
This state is forest plantation with trees like lodgepole pine planted specifically to replace previously degraded forests and to increase productivity of the site for economic profitability. Subsequent harvests and replanting will take place at maximum wood accumulation. Thinning to reduce insect or pathogen outbreaks will help maintain the resiliency of this State. Conversely, no management action may reduce the resiliency of this State.
With the large spruce trees being targeted during the first rounds of logging, what was left of these trees was minimal to none. Instead, sites that would have been dominated by Engelmann spruce became more often dominated by subalpine fir with only a scattering of Engelmann spruce (1.1). Logging effects, along with associated mechanical and fire disturbances, open the canopy and allow for the expansion of the herbaceous understory
Mechanism
Sites that have had the most intense logging pressure have also had greatest degree of forest soil erosion and soil compaction. Once the forest reaches a certain level of degradation, managers often decide to focus on favoring one tree, usually lodgepole pine because of its greater growth rate and merchantability. This requires a clear cut and slash disposal followed by planting.
A less costly alternative compared to logging/slashing/replanting is to defer logging and control livestock grazing to allow whatever self-regenerating trees that occur on the site to recover. This process could, however, be thwarted by heavy game usage (i.e. elk utilization of aspen, or snowshoe hare utilization of subalpine fir).
Model keys
Briefcase
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Ecological site groups
Major Land Resource Areas
The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.