Forest Age and Growth Rate of Ponderosa Pines at the Forest–Meadow Boundary; Canyon Creek, MT

Abstract

The forest–meadow boundary is an ecotone where the encroachment of trees is typically restricted by some limiting environmental factor (soil moisture, grazing, fire frequency). The Triple 8 Ranch field station in Canyon Creek, Montana provides an opportunity to study this boundary where grazing has been relatively limited since settlement. This study is a baseline investigation of Ponderosa pines along a transect encompassing slopes of different aspect (north vs south facing). Tree cores will be collected along the transect, along with data on stand type, tree size, forest-meadow boundary conditions, surface slope and aspect. Annual rings counted from cores will be used to determine germination dates and growth rate of trees in closed stands, ‘edge’ trees, and individual ‘pioneer’ trees advancing from forest edge into meadow. Measurement of ring widths will allow comparison of growth rates at different physical settings, and also of tree growth response to seasonal/annual climatic variations recorded over the last century. This study will provide a reconnaissance level forest history, will help inform forest management practice at the Triple 8, and also improve our understanding of climatic influences on growth response of Ponderosa pines at lower elevation tree line.