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Restoration Ecology - Week 2


I. Introduction
A. Term originated with H.D. Thoreau (1860), who recognized that hardwoods follow pines after logging in New England
B. Examples
1. Glacier Bay Alaska - William Cooper, following glacial retreat
Pioneer: blue-geen algae, lichens, horsetails, liverworts
Dryas: dryas, willow, cotton wood, alders, spruce
Alder: alders
Spruce: spruce
2. Lake Michigan Sand Dunes - H.C. Cowles, emphasized dynamic nature of succession, anti-Clementsian
black oak, white oak, red oak, hickory
beech - maple
3. Old Field succession in North Carolina - Henry Oostings and Catherine Keever
crabgrass and horse weed -1st year
aster and ragweed - 2nd year
broomsedge and pine seedlings - 3rd year
pines 15 - 60 years
pine anad hardwood understory - 60 -150 years
hardwoods - after 150 years
4. South Florida Pinelands
Florida trema, bracken fern
gumbo limbo, poison wood, wild tamarind
paradise tree, lancewood, mahagony,
mastic, pigeon plum, inkwood
C. Generalizations
1. Small plants precede big plants
2. Annuals precede perennials
3. Herbs precede shrubs
4. Shrubs precede trees
5. Pines precede hardwoods
6. Biomass increases
7. Physiognomy increases in complexity
D. Definitions
1. Succession is a directional change in the species composition or structure of a community over time. Excludes seasonal and long-term climate induced change. Absence of change marks climax community, or rather the absence of cumulative change, fluctuation around a mean are acceptable - dynamic equilibrium (Barbour et al. 1980, 1999)
2. Succession - the entire process of change form the first seral community to the climax is called a succession or sere
3. Primary succession - establishment of plants on land not previously vegetated, includes hydrarch and xerarch succession
4. Secondary succession - establishment of plants on previously vegetated land that has been subject to human or natural disturbance. Secondary succession on abandoned cropland is called old-field succession.
5. Progressive succession - new communities have greater complexity and biomass than the communities they replaced, habitats are more mesic
6. Retrogressive succession - simpler communities, lower biomass, more hydric or xeric
7. Chronosequence - seral stages of differing ages
8. Topsequence - a mosaic resulting from topographic differences which bear no successional relationship to one another, e.g. N-facing vs. S-facing slope
9. Climax - terminal stage of ecological succession, a biotic community in equilibrium with existing environmental conditions
10. Climatic climax - more or less stable community in which the major factors affecting the vegetation are climatic; a climax community on level mesic ground
11. Edaphic climax - climax that occurs on an atypical soil
12. Monoclimax - single climax, climatic climax of a region
13. Polyclimax - mosaic of climax types that occur in a given region
14. Subclimax - stage preceding a climax that is maintained by biotic or abiotic factors

II. History of Ideas
A. Clements (1916) equated succession with organismal development the unit or climax formation is an organic entity. ... As an organism the formation arises, grows, matures, and dies. ...Furthermore, each climax formation is able to reproduce itself, repeating with essential fidelity the stages of its development. The life-history of a formation is a complex but definite process, comparable in its chief features with the life-history of an individual plant.
1. nudation - exposure of substrate
2. migration
3. ecesis - germination, early growth and establishment
4. competition
5. reaction - autogenic effects of plants on the habitat
6. stabilization - the climax
7. Steps 2-5 are repeated until the climax
B. Gleason (1926) - "The individualistic concept of the plant community"
C. (Tansley 1935) - recognized two driving forces
1. Autogenic or bioitic succession driven by organisms
2. Allogenic succession driven by external factors beyond the control of organisms - climate change, sea level change, introduced organisms
D. Egler (1954)
1. Initials floristic composition (IFC) was important at least in the early stages
2. Relay floristics (RF) termed used to describe Clementsian succession
E. Odum 1969 - Ecological succession involves the development of ecosystems; it has many parallels in the developmental biology of organisms, and also in the development of human society
1. It is an orderly process of community development that is reasonably directional and therefore predictable
2. It results from modification of the physical environment by the community-controlled even though the physical environment determines the pattern, the rate of change, and often sets limits as to how far development can go
3. It culminates in a stabilized ecosystem in which maximum biomass (or high information content) and symbiotic function between organisms are maintained per unit of available energy flow
From Barbour et al. 1990

Trait Early Stages Late Stages
Biomass Small Large
Physiognomy Simple Complex
Leaf orientation Multilayered Monolayered
Nutrient storage Soil Biomass
Role of Detritus Minor Important
Mineral cycles Open Closed
Net Primary Production High Low
Site quality Extreme Mesic
Importance of macroenvironment Great Moderated
Stability Low High
Plant diversity Low High
Life Histories r K
Dispersal Wind Animals
Propagule Longevity Long Short

F. Whittaker (1970) - . . . communities go through progressive development of parallel and interacting changes in the environment and communities, a succession. Through the course of succession community production, height, and mass, species-diversity, relative stability, and soil depth and differentiation all tend to increase (though there are exception). The endpoint of succession is a climax community of relatively stable species composition and steady-state function, adapted to its habitat and essentially permanent in its habitat if undisturbed. Pattern Climax.
G. Drury and Nisbet (1973) - in the widest sense succession refers to observed sequences of vegetation association or animal groups some occur in space some in time, in ecological literature usually limited to sequences in time continues until the species combination best suited to the regional climate and the site are established. ... most of the phenomena of succession can be understood as consequences of differential grow, differential survival (an perhaps also differential colonizing ability) of species adapted to growth at different points on environmental gradients. The appearance of successive replacement of one "community" or association" by another results in part from interspecific competition which permits one group of plants temporarily to suppress more slowly growing successors. The structural and functional changes associated with succesional change result primarily from the known correlations in plants between size, longevity , and slow growth.
H. Horn (1975) - tree by tree replacement a Markovian process, stochastic process in which transitional among various states occur with characteristic probabilities that depend only on the current state and not on any previous state.
I. Connell and Slatyer (1977) - Succession refers to the changes observed in an ecological community following a perturbation that opens up a relatively large space. Three models
1. Facilitation - preparing the ground, facilitation leads to relay floristics, suggest that limited evidence except in primary successions
2. Tolerance - later species able to tolerate lower levels of resources
3. Inhibition - all species resist invasion, first invades preempt the space and occupy it until they die or are damaged, thus releasing resources. Process continues until species replace themselves
J. Christensen and Peet (1981) - all three processes can operate at one time
1. Old-field stage, before biotic interactions are as important - tolerance model is appropriate
2. Young to intermediate-age pine stands - inhibition applies
3. Mature pine - facilitation occurs
4. Developing hardwood forest - all three are important
K. Grime (1977) - high species change on fertile soils, low species change on infertile soils
L Tilman (1985) - Resource Ratio Hypothtesis - predicts rapid succession with minimal species change on fertile soils and slow succession with greater species change on infertile soils.

III. Relevance to Restoration
A. Restoration is a shortcut to succession
B. Natural establishment slow and stochastic - function of seed sources
C. Unlike natural succession - all species usually added at one time - Are there other options?
D. Knowledge of succession helps identify the target
1. What is the sere? Polyclimax vs. monoclimx
2. What is the successional stage?
E. Individualistic concept (versus organismal) means that maximizing one species may not help others
F. Models of succession suggest mechanism of replacement
1. Facilitation - pioneer species encourage and may even be necessary for establishment of later species
2. Tolerance later species can be added at any time, pioneer species should be added at beginning of restoration
3. Inhibition - pioneer species will inhibit the establishment of later species
4. Random colonization model
IV. Secondary Succession Summary
A. Characteristics of early and late successional plants (Overhead #1)
B. Successional Pathways (Overhead #1)
C. Models of Succession (Overhead #2)
D. Secondary Succession Summary (Overhead #3)
1. Disturbance
2. Recruitment
3. Establishment and growth
4. Environmental modification
a. facilitation
b. tolerance
c. inhibition
d. none
5. Competition
6. Repetition of steps 2-5 until a self-replicating or cyclical system develops
E. Succession - Relevance to Restoration (Overhead #4)
1. Disturbance - Are agents or effects present?
2. Recruitment - Has it been affected?
3. Establishment and growth - Have they been affected?
4. Environmental modification
a. Facilitation - Amelioration may be necessary, or establishing early seral stages suffice
b. Tolerance - Early stages may be skipped.
c. Inhibition - Early stages should not be established.
d. None - Any stage may be established.
5. Competition - How can it be minimized?
6. Repetition of steps 2-5 until a self-replicating or cyclical system develops - What stage should be introduced?