1. Survival of Subnivean vs. Supranivean Plants *The Snow Buttercup and Engelmann Spruce* Winter Ecology – Spring 2005 Mountain Research Station – University of Colorado, Boulder Arden Piland

2. Two Environments Subnivean: The environment below the snow (Snow buttercup) Supranivean: The environment above the snow (Engelmann Spruce)

3. Survival Living through the winter: -most plants well adapted to these stresses Reproduction and success of offspring: -directly related to winter conditions leading into growing season

4. Question(s): What factors affect the reproductive success and the survival of seedlings of the two species? How do the species help to ensure the survival of progeny?

5. Effects of Snowdepth Growing season length - outer regions of snowpack= earlier melt=longer growing season -30% decrease in growing season from shallow to deep parts Soil fertility -shallower depths more fertile (more nutrients) *overtime, more vegetation and microbial activity (Galen and Stanton, 1999) Water availability -more snow in winter = more available moisture

6. Snow Buttercup (Ranunculus adoneus) HemicryptophytesHemicryptophytes Store starch in roots to overwinterStore starch in roots to overwinter Start to grow under snowpackStart to grow under snowpack Emerge with established flowers and photosynthesizing (Stanton et al, 1997)Emerge with established flowers and photosynthesizing (Stanton et al, 1997)

7. Effects of growing season length Seeds -fewer seeds produced in late melt sites (G&S,1991) -33% decrease in seed mass in late melt sites *Larger seeds 6 times more likely to germinate (G&S, 1993)

8. Effects cont… Seedlings *30% increase in production of true leaves in early melt sites *22% decrease in winter survival if didnt produce true leaves in first season

9. Effects of soil fertility Higher nutrient content= more conducive to infection by mycorrhizae Higher starch content in roots More resistant to yearly differences in growing season length (Scherff et al, 1994)

10. Some things they do…. Habitat affinity: more abundant in early melting sites (G&S, 1999) Symbioses with mycorrhizae -Vesicular arbuscular mycorrhizae (VAM) (Mullen & Schmidt, 1993) -Dark-septate endophytic (DSE) fungi (Mullen et al, 1998) Photosynthetic seeds (G&S, 1997)

11. Disscusion/Conclusions Main stresses:Main stresses: -growing season length *affects time for production-less seeds, less viable seeds, weaker seedlings -soil fertility *less nutrient gain, less starch storage, slower growth from snow (problems of growing season), less resistant

12. Engelmann Spruce (Picea Engelmanni) Not limited by snowpack determined growing season..Not limited by snowpack determined growing season.. -water? Yes, but can still set seeds.. Greatest mortality occurs during seedling life stageGreatest mortality occurs during seedling life stage Survival of seedling criticalSurvival of seedling critical

13. Stress factors for seedlings Water availability -in unusually dry year (not much winter snowfall) no seedlings emerged-1 st time in 16 years (Johnson et al, 2004) -multiyear study-most seedlings emerged in wettest year (Germino et al, 2001) -measure of seedling water potentials *lowest levels of photosynthesis when lowest water potentials (Johnson et al, 2004)

14. Stress cont… The problem of low temperature photoinhibition Photoinhibition= low levels of photosynthesis - Low night temperatures + high light exposure High sky exposure= lots of heat lost to night sky=low leaf temperature=frost formation=stomate damage. Next day high light=rapid warming, cant adjust=respiration >>photosynthesis (Germino & Smith 1999) Coupling of effects means reduced photosynthesis. -restricted carbohydrate and energy gain, dont form good roots=more water stress=chance of survival decreases (Johnson et al, 2004)

15. Seedling survival tactics Tree islands -seedling density decreases farther from tree islands * reduces sky exposure (insulation/less light), convective heat gain = less photoinhibition (Germino et al, 2001) Grass cover -90% survival rate *same protection as from trees (Germino et al, 2001)

16. Survival cont.. Crown architecture -needles inclined from horizontal *decreases sky exposure * heat dissipation between needles- gradual warming in day, slower cooling at night (Germino & Smith, 1999) Habitats with water retention -high % new seedlings found on moss layers and fallen logs (Johnson et al, 2004)

17. Yep, still goin….. Ribbon forests -Seedlings establish selves on leeward side *more water available *protection from high light and low temps. (Marchand, 1996)

18. Conclusions of ES seedlings Stresses-Stresses- -#1 water availablity (if low, extremely low levels of photosynthesis, dessication, death) -High sky exposure=low night temps & high day light levels=photoinhibition= plant growth decreased (bad roots) Cope methodsCope methods - choose sheltered habitat (Tree islands/ribbon forests, grass cover) -alter crown structure to reduce photoinhibition - choose site with more water (mosses, logs, leeward side of ribbon forest) SURVIVE!!!

19. SUMMARY Snow buttercup -survival restricted by growing season length and soil fertility -Survive by: *habitat selection (longer growing season, more fertile soil- more/better seeds) *mycorrhizae symbioses (more nutrient acquistion, more explosive growth, longer grow season, more resilient) *photosynthetic seeds (more carbohydrate production, better reserves, better survival )

20. Engelmann Spruce ( seedlings) Survival restricted by: -low temps/high light (photoinhibition, bad roots) -water (less photosynthesis, dessication, death) Ensure survival by: -Increasing cover (tree islands, grass, alter crown structure) -moister habitat selection (leeward of ribbons, mosses, logs)

21. Message: Subnivean (snow buttercup) and Supranivean (Engelmann Spruce) both affected by winter conditions but in different ways: -Subnivean: snowpack restricts length of growing season and alters nutrient availability -Supranivean: snowpack restricts amount of water available but also restricted by poor plant health (reduced roots) from photoinhibition *Plants from both environments developed behavioral and morphological adaptations to ensure their survival.

22. REFERENCES Galen, C, Stanton M.L. 1991. Consequences of emergence phenology for reproductive success in Ranunculus adoneus. American Journal of Botany. 78(7):978-988.Galen, C, Stanton M.L. 1991. Consequences of emergence phenology for reproductive success in Ranunculus adoneus. American Journal of Botany. 78(7):978-988. Galen, C, Stanton M.L. 1993. Short term responses of alpine buttercups to experimental manipulations of growing season length. Ecology 74(4):1052-1058.Galen, C, Stanton M.L. 1993. Short term responses of alpine buttercups to experimental manipulations of growing season length. Ecology 74(4):1052-1058. Galen, C., Stanton, M.L. 1999. Seedling establishment in alpine buttercups under experimental manipulations of growing season length. Ecology. 80(6):2033-2053.Galen, C., Stanton, M.L. 1999. Seedling establishment in alpine buttercups under experimental manipulations of growing season length. Ecology. 80(6):2033-2053. Germino, M.J., Smith, W.K. 1999. Sky exposure, crown architecture, and low-temperature photoinhibition in conifer seedlings at alpine treeline. Plant, Cell and Environment. 22:407-415.Germino, M.J., Smith, W.K. 1999. Sky exposure, crown architecture, and low-temperature photoinhibition in conifer seedlings at alpine treeline. Plant, Cell and Environment. 22:407-415. Germino, M.J., Smith, W.K., Resor, A.C. 2001. Conifer seedling distribution and survival in alpine-treeline ecotone. Plant Ecology. 162:157-168.Germino, M.J., Smith, W.K., Resor, A.C. 2001. Conifer seedling distribution and survival in alpine-treeline ecotone. Plant Ecology. 162:157-168. Johnson, D.M., Germino, M.J, Smith, W.K. 2004. Abiotic factors limiting photosynthesis in Abeis lasiocarpa and Picea engelmannii. Tree Physiology.24:377- 386.Johnson, D.M., Germino, M.J, Smith, W.K. 2004. Abiotic factors limiting photosynthesis in Abeis lasiocarpa and Picea engelmannii. Tree Physiology.24:377- 386. Marchand, P.J. 1996. University Press of New England. Life in the Cold. Pg:75-91.Marchand, P.J. 1996. University Press of New England. Life in the Cold. Pg:75-91. Mullen, R.B., Schmidt, S.K. 1993. Mycorrhizal infection, phosphorus uptake, and phenology in Ranunculus adoneus- implications for the functioning of mycorrhizae in alpine systems. Oecologia. 94(2):229-234Mullen, R.B., Schmidt, S.K. 1993. Mycorrhizal infection, phosphorus uptake, and phenology in Ranunculus adoneus- implications for the functioning of mycorrhizae in alpine systems. Oecologia. 94(2):229-234 Mullen, R.B., Schmidt, S.K., Jaeger, C.H. 1998. Nitrogen uptake during snowmelt by the snow buttercup, Ranunculus adoneus. Arctic and Alpine Research. 30(2):121-125.Mullen, R.B., Schmidt, S.K., Jaeger, C.H. 1998. Nitrogen uptake during snowmelt by the snow buttercup, Ranunculus adoneus. Arctic and Alpine Research. 30(2):121-125. Scherff, E.J., Galen, C., Stanton, M.L. 1994. Seed dispersal, seedling survival and habitat affinity in a snowbed plant-limits to the distribution of the snow buttercup, Ranunculus adoneus. 1994. Oikos. 69(3):405-413.Scherff, E.J., Galen, C., Stanton, M.L. 1994. Seed dispersal, seedling survival and habitat affinity in a snowbed plant-limits to the distribution of the snow buttercup, Ranunculus adoneus. 1994. Oikos. 69(3):405-413. Stanton, M.L., Galen C. 1997. Life on the edge: adaptation versus environmentally mediated gene flow in the snow buttercup, Ranunculus adoneus. The American Nauturalist. 150(2):143-178.Stanton, M.L., Galen C. 1997. Life on the edge: adaptation versus environmentally mediated gene flow in the snow buttercup, Ranunculus adoneus. The American Nauturalist. 150(2):143-178. Stanton, M.L, Galen, C, Shore, J. 1997. Population structure along a steep environmental gradient: consequences of flowering time and habitat variation in the snow buttercup, Ranunculus adoneus. Evolution. 51(1):79-94.Stanton, M.L, Galen, C, Shore, J. 1997. Population structure along a steep environmental gradient: consequences of flowering time and habitat variation in the snow buttercup, Ranunculus adoneus. Evolution. 51(1):79-94.

23. Cont… Survival Strategies Habitat affinity, mycorrhizae and photosynthetic seeds = -more carbohydrate production -more reserves -faster growth from snow (longer grow season) -more seeds/ better seeds INCREASED SURVIVAL! YAY!