Fruitful factors: what limits seed production of flowering plants in the alpine?
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Predicting demographic consequences of climate change for plant communities requires understanding which factors influence seed set, and how climate change may alter those factors. To determine the effects of pollen availability, temperature, and pollinators on seed production in the alpine, we combined pollen-manipulation experiments with measurements of variation in temperature, and abundance and diversity of potential pollinators along a 400-m elevation gradient. We did this for seven dominant species of flowering plants in the Coast Range Mountains, British Columbia, Canada. The number of viable seeds set by plants was influenced by pollen limitation (quantity of pollen received), mate limitation (quality of pollen), temperature, abundance of potential pollinators, seed predation, and combinations of these factors. Early flowering species (n = 3) had higher seed set at high elevation and late-flowering species (n = 4) had higher seed set at low elevation. Degree-days >15 °C were good predictors of seed set, particularly in bee-pollinated species, but had inconsistent effects among species. Seed production in one species, Arnica latifolia, was negatively affected by seed-predators (Tephritidae) at mid elevation, where there were fewer frost-hours during the flowering season. Anemone occidentalis, a fly-pollinated, self-compatible species had high seed set at all elevations, likely due to abundant potential pollinators. Simultaneously measuring multiple factors affecting reproductive success of flowering plants helped identify which factors were most important, providing focus for future studies. Our work suggests that responses of plant communities to climate change may be mediated by flowering time, pollination syndrome, and susceptibility to seed predators.
KeywordsPhenology Reproduction Pollination Pollen limitation Climate change
Funding was provided by the Natural Sciences and Engineering Research Council of Canada, the Pacific Institute for Climate Solutions, and the University of Victoria. Two anonymous reviewers provided comments that greatly improved the manuscript. We thank Luise Hermanutz, Andrew Trant, Kimberly Carlson, Kira Hoffman, and Katharine Baldwin-Corriveau for comments on earlier versions. Andrew Sheriff and Erika Dort were instrumental in completing the field work. The experiments comply with the current laws of the country (Canada) in which the experiments were performed.
- Ashman T-L, Knight TM, Steets JA, Amarasekare P, Burd M, Campbell DR, Dudash MR, Johnston MO, Mazer SJ, Mitchell RJ, Morgan MT, Wilson WG (2004) Pollen limitation of plant reproduction: ecological and evolutionary causes and consequences. Ecology 85:2408–2421. doi: 10.1890/03-8024 CrossRefGoogle Scholar
- Dafni A, Kevan PG, Husband BC (2005) Practical pollination biology. Enviroquest, CambridgeGoogle Scholar
- Darwin C (1862) On the various contrivances by which British and foreign orchids are fertilised by insects: and on the good effects of intercrossing. Murray, LondonGoogle Scholar
- Dunne JA, Harte J, Taylor KJ (2003) Subalpine meadow flowering phenology responses to climate change: integrating experimental and gradient methods. Ecol Monogr 73:69–86. doi: 10.1890/0012-9615(2003)073%5B0069:SMFPRT%5D2.0.CO;2 CrossRefGoogle Scholar
- Forrest J (2011) Plant-pollinator interactions in a changing climate. PhD dissertation, Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, CanadaGoogle Scholar
- Galen C, Stanton ML (1993) Short-term responses of alpine buttercups to experimental manipulations of growing season length. Ecology 74(4):1052–1058 doi: 10.2307/1940475
- Haig D, Westoby M (1988) On limits to seed production. Am Nat 131:757–759. Article Stable: http://www.jstor.org/stable/2461676
- Hothorn T, Zeileis A, Millo G, Mitchell D (2012) lmtest: testing linear regression models. R project.orgGoogle Scholar
- Kearns CA, Inouye DW (1993) Techniques for pollination biologists. University Press of Colorado, NiwotGoogle Scholar
- Marshall SA (2006) Insects: their natural history and diversity: with a photographic guide to insects of eastern North America. Firefly, BuffaloGoogle Scholar
- Straka JR, Starzomski BM (2014) Humming along or buzzing off? The elusive consequences of plant-pollinator mismatches. J Pollinat Ecol [Suppll] 13, Available at: http://www.pollinationecology.org/index.php?journal=jpe&page=article&op=view&pah%5B%5D=221
- Triplehorn CA, Johnson NF, Borror DJ (2005) Borror and DeLong’s introduction to the study of insects. Thompson Brooks/Cole, BelmontGoogle Scholar
- Vander Kloet SP (1988) The genus Vaccinium in North America. Research Branch Agriculture Canada, OttawaGoogle Scholar
- Zeileis A, Kleiber C, Jackman S (2008) Regression models for count data in R. J Stat Softw 27:1–25 http://www.jstatsoft.org/v27/i08