Understanding the causes and consequences of plant diversity and distributions is critical for successful stewardship of the world’s biota and to sustain the ecosystem services on which humanity depends. Neutral theory provides insight into stochastic processes such as dispersal limitation that impact on community assembly1. However, species coexistence and range sizes are also necessarily influenced by their function, i.e. ability to acquire and allocate resources for survival, growth and reproduction. Great strides have been made to identify important axes of functional trait variation in plants; for example, the leaf economics spectrum.2,3 Mechanisms underlying how variation in plant architecture and physiology are coordinated with performance and environment, however, remain enigmatic.
Because leaves are the metabolic engines of plants,4 understanding how variation in leaf traits is coordinated with differences in habitat and climate is a critical step to better understanding past and present distributions and better predicting future plant responses to environmental change. Using ferns as a model system because they exhibit the greatest diversity in leaf form and span large environmental gradients, I am testing hypotheses of fundamental structure-function-environment relationships across three biomes in Hawaii, Southern California, and Costa Rica.5 Currently, I’m in Costa Rica conducting a common garden experiment to test for key adaptive and plastic differences in fern responses to light and moisture availability.
____________________________________________________1 Hubbell SP (2001) The Unified Neutral Theory of Biodiversity and Biogeography. Princeton University Press, Princeton, NJ
2 Wright IJ et al. (2004) The worldwide leaf economics spectrum. Nature 428:821-827
3 Shipley B, Lechowicz MJ, Wright I, Reich PB (2006) Fundamental trade-offs generating the worldwide leaf economics spectrum. Ecology 87:535-541
4 Sack L, Holbrook NM (2006) Leaf hydraulics. Annual Review of Plant Biology 57:361-381
5 Creese C, Lee A, Sack L (2011) Drivers of morphological diversity and distribution in the Hawaiian fern flora: Trait associations with size, growth form, and environment. American Journal of Botany 98:956-966
An example of the shadehouses we constructed. Left, photo of casa de sombra quatro exterior. Right, inside a low irradiance treatment section (2% PAR), facing the high irradiance treatment (20% PAR) with replicates of 13 morphologically and phylogenetically diverse fern species randomized across benches.
Ph.D. in progress, Ecology & Evolutionary Biology, University of California, Los Angeles.
M.S. 2007, Integrative Biology, University of Guelph.
Hon. B.S. 2004, Biology & Archaeological Science, University of Toronto.
Creese C. and L. Sack. 2011. Drivers of morphological diversity and distribution in the Hawaiian fern flora: trait associations with size, growth form and environment. American Journal of Botany 98: 956-966.
Creese C. and H. Maherali. 2011. Xylem function and climate adaptation in Pinus. American Journal of Botany 98: 1437-1445.
Pasquet-Kok J., C. Creese, L. Sack. 2010. Turning over a new leaf: multiple functional significances of leaves versus phyllodes in Hawaiian Acacia koa. Plant, Cell and Environment 33: 2804-2100.
Feild T.S., T.L. Sage, C. Czerniak*, W. Iles. 2005. Effects of leaf teeth on transpiration, photosynthesis and guttation in Chloranthus japonicus (Chloranthaceae). Plant Cell and Environment 28: 1179-1190.
*Czerniak = maiden name