Date 2/25/12 Effect of Tree Radiation and Snow Accumulation on Subnivean Plant Life Jane Culkin: EBIO 4100 Spring Semester 2012

Outline of Discussion ✤ Plants in a Winter Climate: Location Leads to Life? ✤ Question of Study ✤ Hypothesis ✤ Methods ✤ Results of Experiment ✤ Conclusions Based Upon Data ✤ Further Discussion

Plants in a Winter Climate: Location Leads to Life? ✤ What leads to more productive plant life in winter: more snow or more radiation? ✤ Both supranivean and subnivean mammals in alpine environments use various techniques to shield themselves from harsh alpine conditions. ✤ Plants too must overcome these heat loss obstacles. ✤ SCREWP ✤ refers to the six vectors, snow, cold, radiation, energy, wind, and predation that form a powerful factor that shapes the direction of evolutionary response to winter amongst all alpine organisms. -Halfpenny Pew and Small 2010

Plants in a Winter Climate: Location Leads to Life? ✤ Definition of “living plant” ✤ Many small alpine plants exist in a dormant state during winter. For the sake of this experiment I will only be referring to plants that are still photosynthesizing. i.e.: green plants ✤ These “living plants" have many heat restrictions ✤ Must be able to maintain above freezing temperatures if they are going to be able to photosynthesize efficiently ✤ functioning of plants is influenced directly and indirectly by temperature and becomes essential in determining the various strategies that have evolved to enable them to cope in heat deficient ecosystems -Ko ̈ rner 2003

Plants in a Winter Climate: Location Leads to Life? ✤ Two General Strategies ✤ heat exchange by radiation ✤ heat conservation by limiting amount of locations that require constant heat within the body of an organism ✤ Different types of plants conduct these various techniques ✤ Mosses have evolved to have very little root systems due to the extensive amount of soil disturbance that is found on a mountain meadow ✤ Vascular plants have evolved to thrive in the sand and clay soils that contain very little nutrients near the base of a tree as oppose to the mountain valley -Marchand Ko ̈ rner 2003

Question of Study ✤ The location of plant life, more so than animal life in many regards, determines the survival rate of the species because plant life does not have the ability to move locations as easily as an animal. ✤ Research Question: When looking at subnivean plant life in subalpine locations, which plants will respond better to winter conditions, those under snow in an open field or those under the protection of an aspen tree? Which manner is more conducive to heat and energy storage?

Hypothesis ✤ My hypothesis, given other research on alpine plants, is that plants that grow near a tree will tend to be larger and more structured than those that grow in an open meadow for they are less exposed to the harsh winter climate due to both the trees’ radiation as well as the covering that the tree provides via its branches.

Methods ✤ Structure of Experiment ✤ plant life in three different locations ✤ four plots under aspen trees and one plot in an open meadow ✤ Each plot had a radius of centimeters ✤ two trees were located relatively close to the meadow ✤ two trees were located near a river bed to see if there would be a difference between the plant life found in the two aspen locations

Methods ✤ Took the air temperature ✤ Took snow temperature every 15 centimeters from the outer rim of the plot up to the tree or center of the plot, in the case of the meadow. ✤ repeated exercise for snow depth and ground temperature ✤ done on both the Northern and Southern side of the tree

Results from Experiment Regression of Temperature of Ground: Tree Two Distance From Tree (inches) Temperature °C P Value: R2: Distance From Tree (inches) Temperature °C Regression of Temperature of Ground: Tree One P Value:0.169 R2: P Value: R2:.8306 P Value: R2:.8306 Temperature °C Distance South to North in Meadow(inches) Regression of Temperature of Ground: Meadow P Value: R2: 0.321

Results from Experiment Depth of Snow to Plant Life Depth of Snow(inches) Amount of plant life (# of living organisms in centimeter area) Linear Regression of Ground Temperatures Temperature °C Distance from Tree (inches ) Meadow Tree 2 Tree P Value: R2:.8306

Trends in Data ✤ Inconclusive temperature results on the ground ✤ tree two had a strong R2 value however, other temperature regressions were not as correlated ✤ Found significant change in types of snow in all aspen and meadow locations ✤ tree one and two had semi frozen ground where as tree three and tree four had moist ground with slight faceting at the bottom of the snow pack but predominantly rounded snow throughout the rest of the pack. ✤ very strong R2 value for snow depth to amount of plant life

Conclusion ✤ Trends in snow depth as well as the inconclusive temperatures of the ground display that my hypothesis was incorrect. The radiation of a tree does not drastically affect plant life. ✤ Depth of snow and moisture content of snow pack plays a larger role in determining the survival rate of non dormant plants in the winter. ✤ Tree three and four were both located next to a stream bed and both contained the largest amount of green plant life which would suggest that the moisture content was larger in those areas and thus the plants had the nutrients that they needed to survive in the winter. Trees one and two, as well as the meadow, did not have access to these resources and thus could not survive as well.

Further Discussion ✤ New Research Question: How does water, in the form of runoff or a stream bed, effect the plant life that is able to remain in a non dormant state throughout winter?

Sources ✤ Ko ̈ rner, C Alpine plant life : functional plant ecology of high mountain ecosystems. Berlin/New York: Springer. ✤ Halfpenny, James C. "Life,Winter, and Adaptation." Winter: An Ecological Handbook. Boulder: Johnson, ✤ Marchand, Peter J. "Life Under Ice." Life in the Cold: An Introduction to Winter Ecology. 3rd ed. Hanover: University of New England, ✤ Pugh, Evan, and Eric Small. "Hydrologic Sciences Student Research Symposium." CU Boulder Hydrologic Studies: Quantitative Studies in Water in the Environment. CU Boulder Hydrologic Studies..