1. Succession: the replacement of one community
by another over time
-- can see gradual change in vegetation,
dominant species
--most often seen following a disturbance
Two major categories of succession
Primary: establishment of life where none
existed before
Secondary: after an existing community
is disturbed

2. Studying succession in one area could take decades
-- old fields provide one solution
-- good records show when agricultural fields
were used and abandoned
-- succession at various stages can be seen at
one point in time

3. Standard sequence of succession:
Pioneer or early successional species (ESS)
-- r-selected weedy species
-- produce lots of seeds, favor disturbed areas
-- high vagility, disperse to disturbed areas rapidly
-- at first, no competition for light, nutrients in soil
crabgrass
broomsedge

4. Middle successional species (MSS)
-- longer-lived, slower growth than ESS
-- begin to shade out ESS species
-- includes perennials (live 3+ yrs) and shrubs

5. Late successional species (LSS)
-- long-lived, slowest growth
-- more K-selected species
-- trees, larger shrubs and other persistent
species

6. Old field succussion of ESS species in NC
Field winter summer winter summer winter summer winter
abandoned II III
Crabgrass
Horseweed
Ragweed
Aster
Broomsedge
flowering

7. Climax Community: the community that will ultimately
dominate and persist in a given environment
-- suggests final sere is ultimate result of
succession
-- outdated concept as communities constantly
change, just rate of change slows
-- no true climax, just a steady state
chaparral grassland redwood forest

8. Succession at a forest in Washington D.C.
Relative density of
saplings large trees
White oak
Black oak
Red oak
Blackjack oak
Tulip tree
White ash
Red maple
Beech
Sugar maple
Undisturbed for
67 years

9. Study of succession important for:
Community dynamics, competition
Forces that regulate community structure
Most communities today in some form of
succession, need to know future changes
Old growth limited and rare, but some in NC