1. Plant Ecology - Chapter 5 Populations

2. Population Growth Births Deaths Immigration Emigration

3. Population Growth Genets - genetically distinct individuals Ramets - physiologically independent but not genetically distinct individuals

4. Population Growth “Birth” - seed production, vegetative clones, mature pollen grains (gametophyte)?

5. Population Growth “Individual” - distinctly separate plants (unitary) or interconnected, related individuals (modular)

6. Population Structure Population size important, but so is the distribution of individuals among different ages/sizes/stages Have differing importance to population

7. Population Structure Animal populations usually age-structured Age determines role, importance to population Age not as important for plants - size is far more important Plant populations stage- structured

8. Population Structure Plant stages frequently based on size - number of leaves, mass, height categories, diameter categories Frequently impossible to determine plant age

9. Population Structure Plants have very flexible growth patterns Can lose parts and shrink from year to year, go through years of dormancy, or not appear above ground in a given year

10. Population Structure Stage structuring difficult under these circumstances Plants can advance directly through stages, remain at some stage, or undergo reversions

11. Population Structure Plant ecologists must keep track of multiple stages and all possible transitions between them

12. Population Structure In structured populations, individuals of different stages make different contributions to future population growth Pre-repro, repro, post- repro

13. Life Cycle Graphs Summaries of transitions between stages

14. Life Tables - Cohort

15. Matrix Models Combine life cycle graphs with life table data to understand which stage classes have the strongest effects on population growth Which stage needs protection? Which stage class is most affected by fire? Which stage limits population growth?

16. Matrix Models Can be used to predict age-based quantities from stage-based data

17. Long-Lived Plants Problems studying long- lived plants Longer life span than researchers! Year-to-year variation in environmental conditions, longer intervals between censuses - misses younger plants

18. Long-Lived Plants Static life tables problematic - assumptions such as stable age structure impossible to justify Incorporate cyclic variability (e.g., pest outbreaks) Compare old to new photographs

19. Variable Population Growth Matrix modeling generalizations allow for estimates not possible two decades ago Long-run population growth rates Extinction probabilities Minimum viable population sizes