Facilitative effects of Cushion Plants in the Hudson Bay Lowlands of Churchill,

Manitoba

Melissa AntoniadisMSc. Candidate, Physical Geography

York University , Department of GeographySupervisory Committee – Richard Bello & Christopher

LortieMarch 26, 2013

Facilitation• Interactions between organisms that are beneficial to at least one

organism & harmful to none of them (Lortie & Turkington, 2008)

Nurse effect • One species provides microclimatic conditions that improves the

establishment, survival & growth of other species

Padilla and Pugnaire, 2006. Retama sphaerocarpa shrub in the Tabernas desert

Cushion PlantsProtect other plants by providing•Shade•Moderated soil & air temperature•Soil moisture•Protection from wind & herbivores•Increased soil quantity & nutrients

Vaccinium uliginosum (Alpine Blueberry) shrub arctic/subarctic alpine species

Why is facilitation relevant?• Nurse plants act as keystone species for many trophic levels & maintain biodiversity• Restoration technique for disturbed plant communities

•Mitigate impacts of global environmental change

Why Churchill, Manitoba?• Global warming is expected to be most apparent in arctic ecosystems

• where 3 ecosystems meet

• Facilitation may play an important role in treeline advancement, especially after forest fires

• 2 studies in recent years found Alpine Blueberry facilitated tree seedlings

Geographic distribution of cushion plant research

Reid, 2011

Trophic Interactions

• Cushion plants have been found to facilitate other trophic levels ie insectsMolenda et al (2012), Reid (2011)

Stress Gradient Hypothesis

• Positive interactions increase with increasing stress in the environment

Twin Lakes Study Site3 sites (100x100m) minimum 50 cushion plants per site

Twin LakesSite 1. White spruce (high elevation)

Site 2. Burned area (medium elevation)

Site 3. Black spruce (low elevation)

Twin Lakes Fire

Town of Churchill

Research Questions1) Are Alpine Blueberry cushion plants

acting as facilitators to other plant & arthropod species, & specifically spruce tree seedlings?

2) Does facilitation increase with increasing environmental stress

3) Is facilitation greater in the disturbed burned area compared to the relatively undisturbed areas?

Measuring Facilitation• Parallel linear transects to select cushion plants & paired

adjacent non-cushion microsites

• Measure area of each cushion plant microsite & use same dimensions for each paired non-cushion microsites

• Record plant species richness & density in each microsite

• Record spruce seedling height,stem diameter & number of whirls

• 9 Ipod nanos to record insect visitations to flowers & leaves

(3/site)

Reid (2011)

What’s Creating the Stress? Measuring Environmental Variables

• Latitude/longitude, elevation & slope (GPS)

• Sunlight - PAR sensors above & below cushions (30 paired microsites per site)

• Water table position - 3 wells (1 per site)

• Nutrients – surface soil samples for pH & N,P,K, from each site & lab analysis (30 paired microsites per site)

• Surface soil moisture (6 cm) - theta probe in moist, intermediate & dry conditions (30 paire microsites per site)

• Temperature/humidity - data loggers one minute intervals for duration of study (3 paired microsites per site)

• Infrared thermometer different times of day to control for other elements ie wind (30 paired microsites per site)

Data Analysis• Two-way ANOVA of plant species richness &

density vs cushion & non-cushion microsites & same for spruce seedlings for density & health measures

• Regression analysis of temperature, sunlight, moisture, & nutrients vs 1)elevation, 2)plant species richness, 3)density

• Chi-square test of frequency of pollinator visits in cushion vs non-cushion microsites

ReferencesAcuna-Rodrigues, I.S., Cavieres, L.A., and Gianoli, E. 2006. Nurse effect in seedling establishment:

Facilitation and tolerance to damage in the Andes of central Chile. Revista Chilena de Historia Natural, 79, 329-336.

 Antonsson, H., Bjork, R.G., and Molau, U. 2009. Nurse plant effect of the cushion plant Silene acaulis (L.)

Jacq. in an alpine environment in the subarctic Scandes, Sweden. Plant Ecology and Diversity, 2, 17-25.  Arredondo-Nunez, A., Badano, E.I., and Bustamante, R.O. 2009. How beneficial are nurse plants? A meta-

analysis of the effects of cushion plants on high-Andean plant communities. Community Ecology, 10, 1-6.

Badano, E.I., and Marquet, P.A. 2008. Ecosystem engineering affects ecosystem functioning in high-Andean landscapes. Oecologia, 155, 821-829.

Brooker, R.W., Maestre, F.T., Callaway, R.M., Lortie, C.L., and Cavieres, L.A. 2008. Facilitation in plant

communities: The past, the present, and the future. Journal of Ecology, 96, 8-34.

Chapin, F.S., Shaver, G.R., Giblin, A.E., Nadelhoffer, K.J. & Laundre, J.A. 1995. Response of Arctic tundra to experimental and observed change in climate. Ecology, 76, 694-711.

Chrimes, D., Lundqvist, L., and Atlegrim, O. 2004, Picea abies sapling height growth after cutting Vaccinium myrtillus in an uneven-aged forest in northern Sweden. Forestry, 77(1),.

Grau, O., Ninor, J.M., Blanco-Moreno, J.M., van Logtestijn, R.S.P., Cornellisen, J.H.C., and Callaghan, T.V. 2012. Shrub-tree interactions and environmental changes drive treeline dynamics in the subarctic. Oikos, 001-011.

Molenda, O., Reid, A., and Lortie, C.J. 2012. The alpine cushion plant silene acaulis as foundation species: A bug's-eye view to facilitation and microclimate. Plos One, 7(5), e37223.

Padilla, F., and Pugnaire, F. 2006. The role of nurse plants in the restoration of degraded environments. Frontiers in Ecology and the Environment, 4(4), 196-202.

Reid, A. 2011. Cushion plants in the alpine of British Columbia, Canada: Systematic review, trophic facilitation, and pollen limitation. A thesis submitted to the Faculty of Graduate Studies in partial fulfillment of the requirements for the degree of Master of Science. York University.

Thank you,Questions?