The effect of tree density and height on tree-flagging of Lodgepole Pines in Niwot’s sub-alpine forest Michael D. Schuster Winter Ecology – Spring 2010 Mountain Research Station – University of Colorado, Boulder

Mechanisms of tree flagging Predominately carried out by wind Krummholz: “Crooked Wood” in German; These are the type of trees/shrubs near or at treeline Reasons for bareness of trunk: lack of SR

In the Big Picture Why is this important? Useful for forestry practices Can put in context of CC scenario Affects passage of mammals

Observations and Hypothesis I noticed that the trees had varying heights of bare trunk and branches, and this general height changed when the trees were either taller or closer together Hypothesis: affected by amount of sun reaching lower branches, not by krummholz or wind as much – As the avg height increases, the height of the bare tree will also increase – As the L.P. Pine density increases, the height of bare tree should also increase (more trees-more coverage-less sun to ground)

Methods 10x10 m transect Clinometer, field tape, flags, snow probe Total density, density of conifers Avg height (clinometer), snow depth

P-value = Site #P value

Conclusions Total L.P. Pine height increases with elevation Bare trunk height is variable—other factors Density increases with elevation % of bare trunk increases with increase in total height No significant results—other variables are affecting the outcome

Other variables to consider – Slope of transect – Aspect of transect (tried to keep this constant) – Elevation – Type of forest (are there deciduous trees) – Amount of exposure (wind – Snow depth (how does this affect height of bare tree) – Inaccuracies with measurements (10 m distance of transect, from tree, density average)

Suggestions for next time Bring an altimeter, measure elevation More accurate measurments of snow depth Find a better way to measure density Choose transects carefully, controlling for: – Slope, aspect, exposure, types of trees (no deciduous) Finally, for next time: BRING A CAMERA

Works Cited Reference articles Arno, Steven F. Timberline: Mountain and Arctic Forest Frontiers. Chp.1 excerpt, prepared by CU. New York, Pictures: – – jpg jpg