factors can contribute to tree invasions of meadows. Knowledge of
the timing and spatial patterning of tree establishment can provide
insight into the factors that trigger or accelerate the invasion
process. In this reconstruction of tree invasion patterns at Bunchgrass
Ridge, we addressed the following questions:
have rates of invasion changed over the past two centuries?
Can temporal trends be explained by climatic variation or do they
suggest that other factors are important?
is establishment spatially structured?
there evidence of biotic interactions in the spatial associations
lodgepole pine and grand fir contributed differently to the dynamics
mapped all live (n = 5,486) and dead (n = 1386)
trees >1.4 m (4.6 ft) tall in four of the 1-ha (2.5 acre) plots
that would be subjected to experimental tree removal. All live trees
were aged from basal sections (photo, upper right) or increment
cores (photo, lower right).
structures were then developed and uni- and bivariate spatial statistics
were computed to characterize temporal and spatial patterns of invasion.
Based on these age structures, trees were assigned to one of two
age classes for the analysis of spatial patterns: young: <90
yr; old: ≥90 yr.
C. B., J. A. Antos, J. M. Rice, R. D. Haugo, and N. L. Lang.
2010. Tree invasion of a montane meadow complex:
temporal trends, spatial patterns, and biotic interactions.
Journal of Vegetation Science 21:717-732. Request reprint