From Arkansas to Ontario: Understanding Climate and Climate Change Impacts on Sugar Maple Range Limits

EPA Grant Number: FP917234
Title: From Arkansas to Ontario: Understanding Climate and Climate Change Impacts on Sugar Maple Range Limits
Investigators: Putnam, Rachel Cope
Institution: University of Minnesota
EPA Project Officer: Packard, Benjamin H
Project Period: September 1, 2010 through August 31, 2013
Project Amount: $111,000
RFA: STAR Graduate Fellowships (2010) RFA Text |  Recipients Lists
Research Category: Fellowship - Global Change , Academic Fellowships


Forest ecosystems will be affected by global climate change in multiple ways, from changes in community composition to shifts in species distribution. The long-term goal for this research is to determine the relative importance of climate and biotic interactions on plant ranges to better understand how climate change will affect range limits of temperate tree species and forest community dynamics. The current objective for this project is to determine how climate interacts with competitive and facilitative dynamics to define the range limits of sugar maple.


Rapid changes in global climate are likely to have multiple effects on forest ecosystems. Plant ranges are already shifting, which in turn alters plant communities and competitive interactions between species. This study will examine how climate and biotic factors shape the current range limit of sugar maple, identify population differences in response to climate and competition, and clarify our understanding of how novel climate conditions may affect biotic interactions and forest ecosystems.


Sugar maple seeds and seedlings were planted in the forest understory at ten locations along a latitude and climate gradient extending across and beyond this species’ range. To identify population-specific responses to climate and neighbors, seeds and seedlings from populations in Minnesota, Iowa, and Missouri were planted at each site. To determine how biotic interactions affect growth and survival across the climate gradient, competition was reduced in half of the plots by clipping nearby vegetation, whereas vegetation in remaining plots was left intact. Neighbor removal treatments will be repeated during each growing season of the study. Where present, sugar maple seedlings naturally growing at each site will receive identical treatments as a control for the effects of transplanting. Annual seedling growth, survival, and population-specific phenology will be recorded at all sites.

Expected Results:

Climate is an important factor limiting plant ranges, especially at northern range margins. Therefore, sugar maple growth and survival are expected to be poor beyond the northern edge of its range. At the northern range margin, the presence of neighbors is expected to mitigate the limiting effects of climate through facilitation. At the southern range margin, neighbors are expected to exacerbate the effects of climate through competitive interactions, and sugar maple experiencing reduced competition is expected to have high growth and survival. It is hypothesized that sugar maple is less competitive relative to other woody species in the southern part of its range due to a significantly lower growth rate than southern competitors and an optimum temperature for photosynthesis that matches the climate less well than competitors’. At any given site, it is expected that the sugar maple population closest to its native region will be best adapted to local climate and competition and therefore have the highest growth and survival.

Potential to Further Environmental/Human Health Protection:

Plant ranges are already shifting in response to climate change, which in turn alters plant communities and interactions between species. Determining which factors are foremost in constraining plant ranges is therefore critical to maintaining the diversity and overall health of forest ecosystems. Forest ecosystems are important for carbon storage and nutrient cycling, as well as local and regional economies; understanding how climate and competition interact to affect tree growth is crucial to predicting how forests may respond to novel climate conditions.

Supplemental Keywords:

climate change, range limits, sugar maple, competition, facilitation, biotic interactions,

Progress and Final Reports:

  • 2011
  • 2012
  • Final