• Dr. Wayne R. Hawthorn, B1 280, 888-4567 ext. 32117, e-mail: wrhawtho@uwaterloo.ca
• Krebs, C. J. 2001. Ecology: The experimental analysis of distribution and abundance. 5th edition. Benjamin Cummings. San Francisco, CA. 695 pp. ISBN 0-321-04289-1

marks

• assignments 3x10% = 30%
• uwace quizzes best 3 of 5 x 2% = 6%
• midterm 24% 50 mins
• final 40% 2.5 hours

• community: assemblage of interacting species and their relationships
• community characteristics: biodiversity, relative abundance, growth form physical structure, trophic structure, temporal dynamics (succession, non-equilibrium dynamics)
• ecosystem function: processes that keep an ecosystem working/changing (eg primary production, nutrient cycling, decomposition)
• Rivet Hypothesis (species proportional to functions) vs Redundancy Hypothesis (after N species, functions level off)
• super organism (no) vs Individualistic School (yes)
  • supported by community association analyses, complexity of plant associations due to environmental gradients, paleopollen data
• ecotone: transition area between communities
• measuring species independence
  • 2x2 contingency table (species 1 vs species 2, present/absent)

a b
c d

• chi²: (ad-bc)²N/(a+b)(c+d)(a+c)(b+d)
• ad > bc = positive association; ad < bc = negative association
• disarticulation: past communities members occurred in very different proportions and combinations than today (ugh, not real definition...)
• refuge: shelter from trouble
• measuring place similarities
  • 2x2 contingency table (place 1 vs place 2, # species present/absent)
    • x = column 1 sum, y = row 1 sum
    • measure with binary, proportional, or quantitative similarity coefficients
    • Jaccard: a/(a+b+c)
    • Sorensen: 2z/(x+y) (z=a)
    • probs: influenced by sample size (number of individuals) and species richness
  • measuring abundance: density, frequency (chance of finding a given species within a sample), cover/dominance (plants' vertical projection onto ground)
  • proportional/percent similarity coefficient: takes species abundance into account
    • PS = sum of lowest % over all species in a pair of stands
  • quantitative similarity coefficients
    • distance coefficient: 1-sqrt(sum of squares of differences between sites)
    • Morisita (1959)/Horn (1966) index of similarity: best one since relatively independent of sample size
  • dendrogram: one axis of similarity, connect sites together

• indicator species: to use one/few species for community identification, to assess community health
  • criteria: stable taxonomy, natural history known, ease of surveying, niche, associated with other species
  • rarely can be a single species, eg. tree swallows (guilds may be better)
  • some eg. butterflies may be just visiting
  • good choices: earthworms, benthic insects (ephemeroptera+plecoptera+trichoptera)
• target species: ones you're interested in
  • choosing target species: umbrella species (those needing big ranges), charismatic (aka flagship), keystone (impact > biomass)
    • usually important (politics, economics, etc.)

• succession: community developing by it acting on the environment leading to new species there; one community replacing another
• initial floristic composition model: all spp there from start (seeds/roots = propagule pool/seed bank); individualistic; short-lived fast-growers then opposite
• null model: Lawton, 1987
• Connel and Slatyer 1997
  • facilitation model: species increase favourability for other species (until they don't)
    • previously supported by Glacier Bay (N-fixers then N-needers); however N-needers germination inhibited, seedling growth facilitated early
  • inhibition model: spp fight competition (replaced when die or external factors), seen as main process for when "who is first" is important
    • perhaps supported by lake michigan water level fall's sand dunes, some inhibition by oaks
    • one study shows inhibition allowing change through disease

• r (fast growth, many small seeds, short lives) vs K (slow growth (near carying capacity), few big seeds, long lives)
• fish species in 3space: age at maturity, fecundity, juvenile survivorship
• Grime's model

• C-S-R model: 3space of competitive, ruderal, stress-tolerant in triangle (0-100%)
  • problems
    • ST plants are C plants under low resources... C-ST is artificial distinction
    • some climax trees are ST when young, C when old
• trade-offs: stuff can't be good at everything, but not everything conforms and/or may not be obvious (1 big loss=many small gains)
• could divide succession into colonization, maturation, senescence
• succession doesn't necessarily have same climax as before disturbance
  • eg fires in indonesia lead forests to savanna then grassland

• markov process: ignores most stuff, just looks at what saplings replace trees (replacement probabilities)

species

• Ambrosia is the genus for ragweed
• hardwood = deciduous, softwood = coniferous

know some things from the succession characteristics table

things with numbers

• species associating: significance via chi-square, +/- via data
• stand similarity: binary (species presence/absence), proportional, quantitiative