The Community Concept and Ecological Gradients It’s a diverse planet…

These species interact, in complex ways, with one another- and with the constantly changing environment. And the complexity multiplies…

Community Ecology is science’s attempt to grapple with this complex world...

What is an ecological community??

Figure 18.22b

Figure 16.7

Dr. Fredrick Clements: The Community as Superorganism

Figure 16.12a

Dr. Henry Gleason: The individualistic hypothesis of community organization

Figure 16.12b

Figure 18.22a

Vegetation of the Smokey Mountains R. H. Whittaker (1920-1980) Vegetation of the Great Smokey Mountains (Ecological Monographs 26: 1-69) Figure 18.22a

Figure 18.22b

a. Tilia heterophylla; b. Halesia monticola; c. Tsuga canadensis; d. Quercus alba

Figure 18.22c

Which archetypal view of the community does this support? Figure 18.22c Which archetypal view of the community does this support?

Edaphic gradient (salinity)

Edaphic gradient (water-logged soil)

Persistent-disturbance gradient Fire

tohee veery

Figure 16.9

Figure 16.6

Temporal gradients (long-term) 1) Climate changes constantly 2) This change alters the tolerance vs. competition balance for species. 3) In response, species’ ranges shift- and thus- gradients move in space. 4) This dynamics is unending, what we think of as static (e.g., maple forests in New England) isn’t.

Figure 18.18

Margaret Davis: Roger’s Lake Ecology (50:409-422), 1969

Figure 18.19

Figure 18.20

http://www.ncdc.noaa.gov/paleo/pollen/viewer/webviewer.html

Shorter-term temporal gradients are successional changes…. Figure 18.1

Ecological Gradients