1 Gradient analysis a Analysis of species composition along an environmental gradient b Usually reveals individualistic response 2 Ordination a Method for arranging communities in similarity space based on a large series of community variables b Community variable i Trophic structure ii Species diversity iii Dominance iv Growth form and structure v Relative abundance c Take these five and more do for a series of stands spatially isolated patch i Sand dunes and whales 1 Sand dunes have patchy vegetation 2 Take 50 stands of sand dune vegetation 3 Take 20 variables d Uses principal component analysis i Related to multiple linear regressions e principle component 1 i Explains most of the variation between most of the stands and components ii Low PC1 is associated with low species diversity iii Higher PC1 is associated with high species diversity f Principle component 2 i Explains less g Tilman best competitor for soil moisture i Draw down the resource below what everyone else needs ii Intense interspecific competition iii No interspecific competition at the wettest sites h Permits a test of what matters in community competition i Indicates that communities are not completely haphazard assemblages 3 Distributional analysis a Looks for similar patterns of geographic distribution among community members b Close correspondence suggests integration c Broad correspondence is seen but detailed correspondence often lacking d Actual distributions suggest loose if any integration i Closer to Gleason than Clemets 4 Problems of boundaries in space a Have the pertinent variables been sampled b Are stands in equilibrium c Clement s monoclimax hypothesis i want to study ones under boardwalk not on dune because they have interference ii Stands may not be in equilibrium d Are interactions not specific species integrated i Black Oak doesn t reach as far North as Northern Red Oak that difference is more akin to what Gleason might propose but we re doing it species ii Black Oak drops out 700 Miles south of were rest goes iii Imagine species like black oak fills in where black oak drops out 5 Classification a Useful for human purposes ex Conservation i Holds regardless of whether communities are real or not b Usually involves a combination of variables c Ex Great smoky mountains Forests of Tennessee i Topography ii Site moisture iii Elevation iv Slope facet which way a slope is facing 6 Problems of boundaries in time pollen profiles a If a community is truly real in Clememsean sense shouldn t we argue community will persist over time b pollen composition in sediments i Imagine a lake where there are sediments washed into the lake and washed into the bottom of the lake plants around lake pollen blows into water and pollen is heavy enough that it settles at the bottom and counts for sedimentation core thing goes down into lake and take it back to lab millimeter by millimeter asses core composition and can get time can use carbon dating to get really good time for what area around the lake looked like in the past ii Provides evidence of prehistoric plant communities c Reveals marked changes in community composition over time i This change is over and above the change that we would expect d Certain past communities no longer exist i This was a big shock to botanast who studied these analyses that species was living with that species back then Those two species don t coexist in Europe today 7 Equilibiral vs non equilibrial views a Probably not closed system i Clements argued if we should find closed system we would expect an equillibrium over time monoclimax hypothesis black oak in sand dunes in michigan Stands are scattered about in similarity space there is no clustering going on Support gleason so far Measure abiotic circumstances o Spoil moisture likely an important factor in sand dunes Appears to be a coloration between PC1 and spoil moisture but not PC2 Number of species loads heavily onto PC1