Bunchgrass Ridge

Restoration of montane meadows in western Oregon:
A center for research and adaptive management

Photo by James A. Lutz
Ecology & dynamics
of PNW meadows
Spatial and temporal patterns of conifer invasion

History of invasion

Patterns of invasion

Change in meadow extent

Vegetation responses
Vegetation responses to encroachment
Effects of tree age & species
Dynamics of the soil seed bank

Other studies
Gopher disturbance in meadows

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Ecology & dynamics
of PNW meadows

Introduction
Knowledge of spatial and temporal trends in conifer invasion is critical to understanding the natural dynamics of forest-meadow boundaries and to establishing a baseline for assessing future change. In this analysis, we addressed the following questions:
  • Has tree invasion at Bunchgrass Ridge been chronic or episodic?
  • Are invading trees spatially aggregated?
  • Has tree invasion been concentrated along edges or do isolated trees invade open meadow forming foci for subsequent invasion?
  • Does initial establishment facilitate further recruitment?
  • How do lodgepole pine and grand fir differ in their invasion patterns and potential interactions?
Photo: Sawing a "cookie" for aging a sapling

Methods

We mapped all live (n = 5,486) and dead (n = 1386) trees >1.4 m (4.6 ft) tall in four 1-ha (2.5 acre) plots (experimental plots that would subsequently be logged). All live trees were aged from basal sections (upper right)or increment cores (lower right) .

Age structures were then developed and uni- and bivariate spatial statistics were computed to characterize temporal and spatial patterns of invasion.
Photo: Coring near base of tree
Antos, J. A., et al. In prep. Spatial and temporal pattern of tree invasion in a montane meadow complex in the Cascade Mountains of Oregon, USA.

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