TEACHING ALL VOLUMES SUBMIT WORK SEARCH TIEE
VOLUME 6: Table of Contents TEACHING ISSUES AND EXPERIMENTS IN ECOLOGY
ISSUES: FIGURE SETS

Figure Set 2: What are the effects of herbivory on population growth rate?

Purpose: To understand how a demographic matrix model works using a modeling program (R). To use demographic modeling to calculate population growth rate for control plants and then modify the model to understand how herbivory treatments change the results. Students will find that individual level consequences (examined in figure set 1) do not always translate into population level consequences. Students will then calculate an elasticity matrix to understand that not all vital rates contribute equally to the population growth rate.
Teaching Approach: Think-pair-share
Cognitive Skills: (see Bloom's Taxonomy) — Knowledge, Comprehension, Interpretation
Student Assessment: essay quiz

FIGURE SET

Figure 2

Figure 2. The life cycle of Lespedeza cuneata plants in the control treatment. Each circle represents a particular size class, which is based on number of branches. In addition, there are two different types of seed banks (SB) in the life cycle depending on whether the seed was produced from a cleistogamous (CLSB) or chasmogamous (CHSB) flower; these represent seeds that do not germinate immediately but have the potential to germinate in later years. Each arrow represents a transition within the life cycle that occurs from one year to the next. For example, the arrow that goes from small to medium indicates the probability that a plant that is small in year t will grow to a medium plant in year t + 1. The arrow that goes from small to small is the number of seeds produced by plants in the small stage class that germinate immediately and become small plants themselves in year t+1. Modified from Schutzenhofer, M.R. and Knight, T.M. 2007. Population effects of augmented herbivory on Lespedeza cuneata: Implications for biological control. Ecological Applications 17 (4): 965-971.

Note: This image has been updated since its initial publication to address an error.

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