Graduate Thesis Or Dissertation
 

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/08612t157

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Abstract
  • In 1970 a phytosociological reconnaissance consisting of 135 plots in the Subalpine Meadow Zone was made. These samples were sorted using an association table and several Alpine Zone and very early seral communities were set aside, An additional hundred plots taken by M. J. Hamann were incorporated with these and compiled in another association table and combined in a two-dimensional ordination. This analysis yielded 18 major and 16 minor described community types which were clustered into five vegetation types. A key to the vegetation and community types is also presented. Soil moisture and temperature data were taken during 1971 and 1972 and are used to help characterize selected important communities. Soil moistures did not drop much during either season, although differences between communities are apparent. The difference in temperatures (of the top 2 cm of soil) of the same selected communities were more striking. The Festuca dominated communities experienced soil temperatures over 35° C, while maximum temperatures in other communities rarely ranged over 20° C. Low night-time temperatures were relatively similar from community to community, ranging from near freezing to about + 5° C. Several successional patterns were uncovered. In general the communities in the Low-Herbaceous Vegetation Type are early seral and are replaced by members of the Wet-Sedge, Lush-Herbaceous and the Dry-Grass Vegetation Types. Trees appear to be invading all vegetation types variation in pattern and frequency. This variation is attributed to differences in soil moisture and temperature and depth and duration of winter snowpack. Analysis of the ages of invading trees indicates that there was an intensive invasion in the early 1930's and several other minor invasion periods Several factors are discussed which must be favorable for the successful invasion of meadows by trees. The Subalpine Meadow Zone, using vegetation types as map units, is mapped at a scale of about 1:50,000 The total area of the meadow vegetation in the zone is 14,650 acres (6,000 hectares). The entire zone including open subalpine woods covers 24,650 acres (10,000 hectares).
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