Natural Resources
Conservation Service
Mesic Xeric North Slopes 15-25 PZ
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1B
Extensive timber harvest
More details -
Restoration pathway R2A
Forest restoration, stand replacing fire
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
A forested community, this site occurs across the landscape as a mosaic of plant community phases characterized by variation in forest structural stage (tree age, density and cover) and plant community composition and driven by historic fire regimes. Historically, many dry ponderosa pine – Douglas-fir forests would have cycled from a shrub/tree initiation phase (1.1) to a young forest stage (1.3) to a mature forest phase (1.4) with a fire regime characterized by frequent surface and mixed fires. Fire exclusion can lead to closed canopy and dense understory stocking conditions represented by Communities 1.2 and 1.5 which can be more vulnerable to stand replacing fires. The Reference Community within this state is that of an open, mature, savanna like ponderosa pine stand represented by Community Phase 1.4. Historical evidence suggests that this community type was common across the landscape prior to selective logging and widespread fire suppression, which can alter fire regimes, reduce understory cover, and lead to a greater frequency of high severity fire. Given the likelihood that this state, even in the best condition and highest potential, will almost always include at least some component of exotic species regardless of management inputs, this may also be referred to as the “current potential state”. In this document, the term “reference state” is used synonymously with “current potential state” for the sake of simplicity.
Dominant plant species
Douglas-fir (Pseudotsuga menziesii), tree
ponderosa pine (Pinus ponderosa), tree
common snowberry (Symphoricarpos albus), shrub
Submodel
Communities 1 and 5 (additional pathways)
1.1. Stand Initiation
1.5. Mature Forest, Closed
Description
This alternative state represents the many variations of timber harvesting that can occur on this site. This may result in a number of manipulated community types and pathways depending on strategies surrounding harvest, weed control and replanting. Selective removal of large ponderosa pine may advance succession and favor maturation of shade tolerant trees such as Douglas-fir.
Dominant plant species
Douglas-fir (Pseudotsuga menziesii), tree
Submodel
Mechanism
Extensive timber harvest followed by continual management for timber production that has significantly altered species compositions and resulting disturbance responses.
Mechanism
Ecological forestry practices may promote a return to Reference State. Stand replacing fire may lead to a transition to Community 1.1 of the Reference State if soil compaction is not severe, species composition has not been significantly altered and tree seed source is available.
Context dependence
Alterations of forest tree species composition, as well as soil compaction and surface disturbances due to large machine usage may hinder passive forest reestablishment.
Model keys
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Ecological sites
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.
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