Bunchgrass Ridge: A center for research and adaptive management

Although direct evidence is sparse, many dry-site meadows in the western Cascades (and elsewhere in the Pacific Northwest) likely owe their origin and maintenance to fire.

Dendrochronological studies indicate that prior to suppression by humans, natural fires in the montane zone probably occurred at intervals of 100 to 150 yr.

Historical documents also suggest that native Americans, and subsequently sheep herders, burned meadows to increase forage. However, with cessation of sheep grazing, changes in climate, and exclusion of wildfire, conifer encroachment has become widespread.

Timing of tree establishment corresponds with exclusion of sheep and packstock. Triggered by a release from grazing pressure and by an extended period of cooler, wetter weather, conifer seedlings began to invade many dry-site meadows in this region in the 1940s and 1950s. (See graph, below)

Recruitment has accelerated with time, as established trees have modified the biotic and abiotic conditions that once inhibited establishment.

In some instances, local environments have been so altered that invasion has continued even during periods of relatively unfavorable climate.

Past research. Considerable research has addressed the temporal patterns and correlates of conifer invasion in this region (Miller & Halpern 1998).

However, little research has been devoted to the ecological consequences of encroachment, or to the potential for restoration of montane meadows through tree removal and prescribed fire.

A recent issue of PNW Science Findings describes current research on montane meadows. Click here for a list of additional readings.

Retrospective and experimental studies at Bunchgrass Ridge are designed to answer these questions.

Bunchgrass Ridge.

Rebel Rock.

Dates of tree establishment along a forest-to-meadow transect
at Ollalie Meadow in the Three Sisters Wilderness, Oregon.

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Conifer encroachment in PNW meadows