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Boreal Forest Dynamics at the Hardwood Ecotone

Shade Tolerance and Functional Niche Differentiation


Author(s)

Charles J.W. Carroll
Forest and Rangeland Stewardship
Colorado State University
cjwcarroll@gmail.com
Miranda D. Redmond
Forest and Rangeland Stewardship
University of Colorado
miranda.redmond@colostate.edu

Abstract

This “clicker” case uses a handout and a PowerPoint presentation to guide students through the interpretation of three key traits of two dominant boreal species in the high elevation regions of northern New Hampshire to develop hypotheses concerning each species’ shade tolerance. Students are given actual data to assess how these species differ in functional traits and to draw inferences about the species’ relative shade tolerance. Beginning with classical niche theory and advancing to the use of functional traits to define the niche or trait-space of each species, students develop hypotheses about species competition based on niche overlap and how competitive interactions may change with species migrations in the future. Lastly, to emphasize the importance of critical thinking, students consider the limitations of this study based on the study design, identifying problems and generating solutions to expand the applicability of these findings. The case is appropriate for a variety of upper-level undergraduate courses including forest ecology, plant ecology, plant physiology, and ecogeography.


Objectives

  • Explain how three key traits are related to shade tolerance: leaf mass per area, wood density, and leaf dry matter content.
  • Explain how plants tolerate low light environments by increasing photosynthetic rates and/or reducing respiration costs.
  • Define a plant’s niche and explain how niche overlap leads to competition among species.
  • Generate hypotheses, interpret data, assess study design, and interpret the implications of results.

Keywords

Niche; functional trait; shade tolerance; trees; ecotone; red spruce; fir; shade; forest; leaf mass; wood density; leaf matter

Topical Areas

N/A

Educational Level

Undergraduate upper division

Format

PDF

Type / Methods

Clicker

Language

English

Subject Headings

Ecology  |   Environmental Science  |   Forestry  |  


Date Posted

10/16/2020

Teaching Notes

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Supplemental Materials

The PowerPoint presentation below is used in class to guide discussion.

  
  shade_tolerance.pptx (~5.5 MB)

Answer Key

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