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THE IMPACT OF LODGEPOLE PINE SIZE ON HEAT-FORMED TREE WELLS Created by Philip Neumann Winter Ecology, Spring ‘08 Mountain Research Station – University.

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Presentation on theme: "THE IMPACT OF LODGEPOLE PINE SIZE ON HEAT-FORMED TREE WELLS Created by Philip Neumann Winter Ecology, Spring ‘08 Mountain Research Station – University."— Presentation transcript:

1 THE IMPACT OF LODGEPOLE PINE SIZE ON HEAT-FORMED TREE WELLS Created by Philip Neumann Winter Ecology, Spring ‘08 Mountain Research Station – University of Colorado, Boulder

2 Objective  To further understand the relationship between coniferous trees and their surrounding snowpack.  To link the importance of tree well formation to the rest of the winter ecological community.

3 Two Methods of Tree Well Formation  Snow deflection:  Overhanging branches deflect snowfall  Creates pocket of low snow accumulation  Large affected areas  Melting and Sublimation:  Trees absorb solar radiation  Radiation is reemitted into snowpack  Small affected areas

4 Snow Deflection vs. Melting and Sublimation

5 Factors That Create Heat-Formed Tree Wells  Incoming solar radiation  % solar radiation absorbed by tree  Not due to tree-produced heat  Air Temperature  Sublimation or Melting  Metamorphosis over time  Wind loading/scouring  Additional snow

6 Importance  Trees are a major source of heterogeneity in the snowpack. Tree wells exists at the tree-snow interface.  Large geographic spread  Local modification of snowpack creates a functionally different environment.  Reduced soil insulation by snowpack  Increased melting and sublimation  Current lack of study on heat-formed tree wells

7 Question What is the relationship between trees and their snowmelt patterns?

8 Hypothesis An increase in diameter of tree wells will be directly proportional to the increase in diameter of trees in a 1:1 ratio. Why?  Increased tree diameter increases lowest possible value  Similar heat absorption per unit area from tree to tree  More tree surface area for absorption for larger trees  More snow surface area to heat for larger trees Similar effective warming range

9 Hypothesis

10 Methods  Measure tree well diameter for trees in a 35x50ft plot.  Plot: Sheltered, relatively even stand of planted Lodepole Pine. 35ft downhill from a road clearing, slope of 13*, aspect of 170*  Measurements: Diameter of affected snowpack taken in two directions and averaged for tree well #’s. Diameter of tree measured at snow surface.

11 Transect

12 Results: Tree vs. Tree Well Diameter

13 Results: Tree Diameter vs. Adjusted Tree Well Area (Total Tree Well-Tree Area)

14 Results  Data fits well to a linear equation:  y=2.0591x  R-Squared of.9477  P-value of 4.763E-33  Data exhibits positive slope of ~2cm tree well/1cm tree diameter.  Exponential growth in effected snowpack data.

15 Discussion  The hypothesis is rejected.  Strong, linear fit of the data implies a direct connection between increasing tree size and tree well size.  Slope of ~2 implies that an given increase in tree diameter effects tree well diameter twice as much. WHY? Volume = Height x π(½ Diameter)²

16 Discussion  A change in diameter will affect circumference, and therefore surface area, by the same multiplier.  Explains capture of solar radiation  Accounted for in hypothesis  A change in diameter will affect tree volume by its square  Additional, unaccounted for, factor  Increase in mass and thermal capacity  Increased daily duration of heat transfer

17 Discussion  Larger trees… more effected snow volume  Creates diurnal “thermal islands” in the snow  Dictates snowmelt & sublimation rates May impact available soil moisture in cold season May present easier internivean access May present area to avoid for some… predator access  Increased temperature variation may be important— good or bad—for some species Most likely creates habitat quality gradients May present low-competition niche for some

18 Discussion Future studies:  Heat flux in tree wells  Heat flux inside trees  Photosynthesis rates in large/small trees Determined by diurnal tree stem diameter variation  Microbial activity below tree wells  Burrow entrance/exit

19 Conclusion  Increases in tree diameter result in exponential increases in effected snowpack.  Caused by the thermal capacity of trees  Heat at tree-snow interface creates microclimate  Increased daytime temperatures  Decreased soil insulation  Future studies could focus on:  Soil heat flux below tree wells  Heat flux in trees  The effects of heat flux on tree health and surrounding plant and animal communities

20 Works Cited Hardy, JP, Albert, MR. Snow-induced thermal variations around a single conifer tree. Hydrological Processes, 9: Halfpenny, JC,, Ozanne, RD Winter: An Ecological Handbook. Boulder (CO): Johnson Publishing Company. p Sevanto, S, Suni, T, Pumpanen, J, et al. Wintertime photosynthesis and water uptake in a boreal forest. Tree Physiology, 26: 2006


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