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Community Measurements Indirect Gradient Analysis o Use Importance Values (Sum of Relative Frequency, Rel. Dominance, Rel. Density) Indirect Gradient Analysis o Develop Climax adaptation number for each species (By comparing the stands with different leading dominants) Indirect Gradient Analysis o o o Those stands the most different are placed at either end Those most like the extremes are placed close to them #’s are assigned based on similarity Indirect Gradient Analysis o Use Importance Values (Sum of Relative Frequency, Rel. Dominance, Rel. Density) o Develop Climax adaptation number for each species (By comparing the stands with different leading dominants) o Continuum Index for stand = ∑Imp. Val. x Climax Adaptation # for each species found in stand o Plot the dominant species with point for each stand (Imp. Value on Y axis; Cont. Index on X) Distribution & Abundance Direct Gradient Analysis o Some figure (usually density) plotted against an environmental gradient (such as elevation) Direct Gradient Analysis o If difficulty in measuring environmental factor: • Classify species into ecological amplitude • • • • o Trees: a)mesic b)submesic c)subxeric d)xeric Values assigned (a=0, d=3) For each stand count individuals in each group Then multiply value X # of individuals in that group. Sum products and divide by total # of individuals One value for trees & tall shrubs, one for herbaceous plants, then plot values Continuum classes Possible outcomes Gradual vs. Steep (Whittaker) Great Smoky Mtns. Siskyou Mtns. Ordination o Similar to Gradient Analysis • Stands ordered according to composition and abundance, often with cluster analysis o Stands are plotted on a 2-dimensional grid o Values for each stand assigned to environmental factors are then plotted o Look to see trends of factors that correlate with the spread of the stands studied. o Stands may also be plotted geographically Similarity Index o Coefficient of Community CC = 2Sab/(Sa+Sb) Where: Sa = # of species in sample A only Sb = # of species in sample B only Sab = # found in both samples o Same formulation as the Bray and Curtis Similarity Index (simply different terms used) Old Growth Forests - LS Index o o Northern Hardwood Index 200m X 10m plots (or transect taken) Count trees over 16”dbh and trees with lichen (Collema or Leptogium) o LS index then places the stand in one of the categories seen here