Relative abundance I: commonness and rarity

1. Relative abundance I: commonness and rarity Bio 415/615

2. Questions 1. How does a rank abundance distribution quantify commonness and rarity? 2. What are the three components of the rarity scheme of Rabinowitz? 3. What are three ecological processes that lead to rarity? 4. Why might you manage rare species like chestnut and Venus flytrap differently?

3. Recall rank-abundance distributions (RADs) 889 oak trees, 100 bay trees, 10 maple trees, 1 birch tree 100 10 1 .1 .01 % of individuals 1 2 3 4 Rank by abundance

4. Length of the line changes with diversity Slope generally changes with diversity Slope changes because of the change in evenness that generally correlates with system diversity What would the slope be in a perfectly even community?

5. What influences dominance or non-equitability? • Conditions that promote competitive suppression • Low disturbance, abundant resources • Conditions that deny species membership due to harsh conditions (‘stress’) • allow ‘specialists’ to dominate

6. Grime’s model ‘hump-backed model’ of local diversity 4. Local heterogeneity 5. Species pool size (how many potential colonists?) Species richness 1. Dominance (competition) Standing biomass (sometimes productivity) 2. Stress = reduces potential production 3. Disturbance = removes biomass J.P. Grime 1979

7. What influences dominance or non-equitability?

8. RADs: Disturbance, succession Bazzaz 1975

9. Whittaker 1965 Spruce-rhodo Rich coves Red oak Pine forest Pine heath Heath Fir Geometric (logseries) lognormal Dry or cold Rich, mesic

10. 7 Forms of Rarity based on three characteristics: geographic range, habitat specificity, and local population size (Rabinowitz 1981)

11. 7 Forms of Rarity based on three characteristics: geographic range, habitat specificity, and local population size (Rabinowitz 1981)

12. Rarity in the British Flora (Rabinowitz et al.); 39% no component of rarity 3 kinds of rarity; evidence they are independent 59% Narrow Habitat; 15% Small Range; 7% Small Population

13. Causes of Rarity—Natural Ecological, innate: • Innate biology, Narrow niche, rarity of conditions, climate change • High trophic level species • Vulnerability to natural biological change • Disease, herbivory, predation, mutualism Historical: • Poor dispersal relative to habitat dispersion, historical limits, climate change • Recently evolved

14. Causes of Rarity—Imposed 1. Vulnerability to loss of dynamic process: fire, flood, beaver, disease, herbivory, predation • Increase of white-tailed deer, Loss of panther, elk 2. Sensitive to chemical, physical changes 3. Found in human-exploited habitats 4. Exploited species 5. Area & isolation sensitive species

15. Pseudo-rarity • Global scale is not the only scale at which populations are managed: • Nations • States • Counties / Cities • Parks • Why are species rare at these smaller scales? Geum triflorum, ‘prairie smoke’

16. Pseudo-rarity • Global scale is not the only scale at which populations are managed: • Nations • States • Counties / Cities • Parks • Why are species rare at these smaller scales? Geum triflorum, ‘prairie smoke’

17. Pseudo-rarity • Global scale is not the only scale at which populations are managed: • Nations • States • Counties / Cities • Parks • Why are species rare at these smaller scales? Geum triflorum, ‘prairie smoke’

18. Intrinsic Extinction Vulnerability Local endemics: small range, habitat narrow, island species Small population size Large area needs Large body size-large home range-high trophic level Species of productive habitats used by people Migratory species Highly concentrated populations for breeding Limited dispersal ability Low population growth rate Low genetic variation High dependence on species that are extinction vulnerable

19. Types of rarity: American chestnut • One of the most common, dominant trees of the eastern US before disease introduction • NOW: still widespread but only in small shrub form Large range, locally rare

20. Endothia parasitica -- Chestnut blight A Chinese fungus

23. Chestnut

24. Range collapse of American chestnut after the introduction of chestnut blight

25. Many species were associated with chestnut, so many species participated in the “recovery” Nonetheless: Loss of consistent hard mast Lower carrying capacity for wildlife like black bears 7 species of butterflies extinct Possibly other insects (Butterflies are conspicuous and better known that other groups)

26. Types of rarity: Venus Fly Trap, Dionaea muscipula Endemic (locally abundant)

27. Oconee Bell -- Shortia galacifolia Endemic (locally abundant) "The fairest bloom the mountain knows Is not an iris or a wild rose But the little flower of which I'll tell Known as the brave acony bell.” From "Acony Bell", by Gillian Welch and David Rawlings

28. The story of Shortia 1788, December 9 & 11—Collected by Michaux He called it “a new plant” in his journal from “les hautes montaignes de Caroline” 1839—Unnamed & undescribed specimen discovered by Asa Gray in the Paris Herbarium Gray named it for Dr. Charles Short Gray searched on 3 occasions 1877—Rediscovered on Catawba River near Marion, NC by George M. Hyams (89 years since discovery!) 1886—C. S. Sargent found original local (Keowee River) using Michaux journal

29. Shortia galacifolia

30. Types of rarity: Rugelia nudicaulis Endemic (locally abundant)

31. Torreya taxifolia Endemic (rare)

32. Types of rarity: yellowwood Sparse

33. Types of rarity: baldcypress Predictable (specialist)

34. Types of rarity: Fraser fir Specialist endemic