1. How do snowpack depth and proximity to trees affect subnivean plant growth Robin Reibold Winter Ecology: Spring 2014 Mountain Research Station, University of Colorado, Boulder

2. Background Plant requirements for growth – Temp above freezing – Light for photosynthesis – Nutrients Light snow has the highest insulative value[1] Deep/Dense snow has lower light penetrance[2]

3. Hypothesis Being closer to trees will increase subnivean plant growth – Being near trees will increase snow depth over clear areas[3] – Longwave radiation from tree

4. Deeper snowpack will increase subnivean plant growth – Insulative value – Not too deep, still need light getting through

5. Methods Three types of site – Meadow – Tree in Meadow – Tree in Forest 5 samples at each Measured – Temp, depth, amount of growth W S N E 1 2

6. Observations Many tree sites had a thin layer (1-4cm) of snow on top of a thin layer of ice Despite the ice, some green shoots were still growing under and through Dominant species were grasses – Small number of forbs and mosses The bottom half of the meadow was very wind scoured meaning lower snowpacks

7. Comparison of sites The clear sites all had higher snowpack depths Temperature was seemingly unaffected by proximity to trees T depended on snowpack depth

9. P=0.4758, not significant

10. How snowpack affected the amount of plant growth

11. # shoots compared to % shoots at each site

12. Conclusions Snow depth is a more important factor for subnivean plant growth than proximity to trees Clear areas have higher productivity but trees seem to increase chance of success in a meadow Hypothesis is refuted – Being close to trees has negative effect on growth When combined with deep snow see no growth – Deeper snowpack is best indicator

13. Citations [1]http://www.sciencepartners.info/?page_id=595 [2]Bohren C, Colors of snow, frozen waterfalls and icebergs, JOSA, 23:12:p1646-52, 1983 [3]Lawrence D, Slater A, Contribution of snow condition trends to future ground climate, Climate dynamics, 34:7-8:p969-81, 2010 [4]Kappen L, Plant activity under snow and ice, with particular reference to lichens, Arctic, 46:4:p297-302, 1993 [5]Olofsson J, Ericson L, Torp M, Stark S, Baxter R, Carbon balance of arctic tundra under increased snow cover mediated by a plant pathogen, Nature climate change, 1:p 220-23, 2011