COMMUNITY CHANGE (SUCCESSION) Krebs cpt. 21; pages 403-424; 431 Biol 302 succession

SUCCESSION …. Is the non-seasonal, directional and continuous pattern of colonization and extinction on a site by populations. Is the replacement of one kind of community by another kind; the progressive changes in vegetation and animal life that may culminate in the climax community (Krebs 622) Biol 302 succession

SECONDARY SUCCESSION …. … recovery of a disturbed site. PRIMARY SUCCESSION …. … recovery from a new sterile area that has been uncovered by a retreating glacier, or created by an erupting volcano. SECONDARY SUCCESSION …. … recovery of a disturbed site. Biol 302 succession

PRIMARY SUCCESSION Mt. St. Helens pp403-405 Lake Michigan dunes pp416-419 Biol 302 succession Glacier Bay pp413-416

Ice recession in Glacier Bay, Alaska, since 1760 1940 1860 Krebs Fig. 21.7; p414 1760 Biol 302 succession

SECONDARY SUCCESSION Krebs pp419-422 Biol 302 succession

From Drury and Nisbet 1973 “Succession can be considered as an expression of differences in colonizing ability, growth and survival of organisms adapted to a particular set of conditions on an environmental gradient.”  “The replacement of one of several species or groups of species by others results from interspecific competition and the interactions of herbivores, predators, and disease which permit one group plants to suppress slower-growing or less tolerant ones.” Biol 302 succession

A B C D SUCCESSION PATHWAYS (HENRY HORN) 1. OBLIGATORY SUCCESSION Biol 302 succession

A B C D OBLIGATORY SUCCESSION CHRONIC, PATCHY DISTURBANCE Biol 302 succession

A B C D OBLIGATORY SUCCESSION CHRONIC, PATCHY DISTURBANCE COMPETITIVE HIERARCHY A B C D Biol 302 succession

OBLIGATORY SUCCESSION CHRONIC, PATCHY DISTURBANCE COMPETITIVE HIERARCHY QUASI-REALITY Biol 302 succession

Institute Woods, Princeton, N.J. (Henry Horn) Eastern deciduous hardwood forests Biol 302 succession

Grey Birch, Betula populifera Black Gum, Nyssa sylvatica Biol 302 succession

Beech, Fagus sylvatica Red Maple, Acer rubrum Biol 302 succession

4. QUASI-REALITY GRAY BIRCH BLACK GUM RED MAPLE BEECH GRAY BIRCH Biol 302 succession

Biol 302 succession

No. of individuals IN 50 YEARS GRAY BIRCH BLACK GUM RED MAPLE BEECH Values in cells are percentages, and represent the probability (% probability) that any particular individual tree living now will be replaced by any other individual tree 50 years from now. e.g. out of every 100 individuals of grey birch now living, in 50 years, 36 of those grey birch will have died and will have been replaced by black gum. No. of individuals IN 50 YEARS GRAY BIRCH BLACK GUM RED MAPLE BEECH No. of individuals NOW 5 36 50 9 1 57 25 17 - 14 55 31 3 96 Biol 302 succession

The number of Red Maple in 50 years will be: 50% Gray Birch (now) FOR EXAMPLE: The number of Red Maple in 50 years will be: 50% Gray Birch (now) 25% Black Gum (now) 55% Red Maple (now) 3% Beech (now) Biol 302 succession

The predicted percentage composition of a forest consisting initially of 100% Grey Birch. Age of forest (yrs) Now 50 100 150 200  Data from old forest GRAY BIRCH 5 1 BLACK GUM 36 29 23 18 3 RED MAPLE 39 30 24 9 4 BEECH 31 47 58 86 93 Biol 302 succession

Marine Ecologist, Joe Connell From Connell and Slatyer 1977 FACILITATION TOLERANCE (COMPETITION) INHIBITION Biol 302 succession Marine Ecologist, Joe Connell

                                                                                                                                                                                                                                                                                                                                                                                                    FACILITATION …later stages depend upon early-stage species to prepare a favorable environment for them Biol 302 succession

TOLERANCE…later successional species tolerate lower resource levels [i TOLERANCE…later successional species tolerate lower resource levels [i.e. have lower R*] than earlier occupants, and can invade and displace them by reducing resources to levels below those tolerated by earlier occupants i.e. the community is composed of those species most efficient at exploiting resources Biol 302 succession

INHIBITION…all species resist the invasion of competitors and are displaced only by death, or damage by factors other than competition. i.e. colonizers will hold a site against all comers until death Biol 302 succession

FACILITATION TOLERANCE INHIBITION Biol 302 succession

FIELD ABANDONED IN FALL A study from abandoned farmland illustrates some aspects of Facilitation, Tolerance and Inhibition (see Krebs pp496-498) FIELD ABANDONED IN FALL 1. INITIAL INVASION: Horseweed a winter annual produces abundant seed self-allelopathic Conyza canadensis Biol 302 succession

More susceptible to decaying roots of horseweed, than horseweed 2. NEXT SEASON: Asters More susceptible to decaying roots of horseweed, than horseweed Tolerant of dry conditions Biol 302 succession

3. SECOND AND THIRD SEASONS: Bluestem Seedlings invading since initial abandonment Broomsedge More tolerant of dry conditions than Asters Decaying roots of Horseweed promote growth Biol 302 succession

Bluestem Broomsedge Biol 302 succession

Broomsedge promoted by decaying root TOLERANCE: SUMMARY FACILITATION: Broomsedge promoted by decaying root TOLERANCE: Broomsedge displaces Aster through competition for water INHIBITION: Horseweed seedlings more tolerant of horseweed decomposition than Asters Biol 302 succession

THE RESOURCE RATIO HYPOTHESIS OF PLANT SUCCESSION David TILMAN Biol 302 succession

TILMAN, D. 1985. The resource-ratio hypothesis of plant succession TILMAN, D. 1985. The resource-ratio hypothesis of plant succession. American Naturalist 125:827-852 READING FOR THESE LECTURES: Krebs: selections from pp. 182-186 Biol 302 succession

Resource Ratio Hypothesis One species and one resource One species and two resource Two species and two resources Multiple species and two resources Biol 302 succession

R* Species A birth mortality Resource level [1] Population growth [death] rate mortality 0 1 2 3 4 5 6 7 8 9 10 R* Resource level [1] Biol 302 succession

OPTIMAL FORAGING Any (plant) species will absorb resources in the proportion by which it is equally limited by them. This proportion is the ratio of the two values of R* R* = the Requirement Value i.e. the level of resource required to hold a population (of a species) at equilibrium: i.e. where birth rate = death rate Biol 302 succession

1 3 4 2 SPECIES A Population growth [death] rate SPECIES B Resource 1 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 SPECIES A 1 3 Population growth [death] rate 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 SPECIES B 4 2 Resource 1 Resource 2 Biol 302 succession

Resource Ratio Hypothesis One species and one resource One species and two resource Two species and two resources Multiple species and two resources Biol 302 succession

Species A Resource [2] Resource [1] 8 7 6 5 4 3 2 1 Births [A] > Deaths [A] Population increases Resource [2] Zero Net Growth Isocline [ZNGI]: Births = Deaths Births [A] < Deaths [A] Population declines 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 302 succession

Species B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 Births [B] > Deaths [B] Population increases Resource [2] Zero Net Growth Isocline [ZNGI]: Births = Deaths Births [B] < Deaths [B] Population declines 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 302 succession

Resource Ratio Hypothesis One species and one resource One species and two resource Two species and two resources Multiple species and two resources Biol 302 succession

Species A and B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B] 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 302 succession

A B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B] 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 302 succession

Neither species can survive A B 8 7 6 5 4 3 2 1 Both species can grow A wins Resource [2] ZNGI [A] ZNGI [B] B wins Neither species can survive 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 302 succession

A B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B] 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 302 succession

Neither species can survive A B 8 7 6 5 4 3 2 1 A & B coexist A wins Resource [2] ZNGI [A] ZNGI [B] B wins Neither species can survive 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 302 succession

Plant Ecology Research Assistant for Garry Oak Ecosystem Study Location: Greater Victoria area, Vancouver Island, BC Term: April/May – August 2006 (3 – 4 months) Salary: $1600 – 1800/month (depends on experience) Duties: Vascular plant surveys, environmental data collection, data entry, etc. Qualifications: At least one year of study in Biology, Environmental Studies, Geography etc. - Interest in ecological research - Meticulous personality; highly-motivated, flexible, reliable and fun - Physically fit; valid Driver’s license - Previous field experience and experience identifying plants are assets - Based in Victoria or Vancouver area (Victoria preferred) Apply via resume and brief covering e-mail to: Patrick Lilley, M.Sc. Student, UBC Botany plilley@interchange.ubc.ca Deadline: February 24, 2006 More details at www.lilley.ca/jobs Biol 302 succession

Neither species can survive A B 8 7 6 5 4 3 2 1 A & B coexist A wins WHY? Resource [2] ZNGI [A] ZNGI [B] B wins Neither species can survive 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 302 succession

A B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B] 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 302 succession

A B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B] 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 302 succession

Resource Ratio Hypothesis One species and one resource One species and two resource Two species and two resources Multiple species and two resources Biol 302 succession

Resource [2] Resource [1] A B C D E 8 7 6 5 4 3 2 1 A B C D E 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 302 succession

A AB B BC C CD Resource [2] D DE E Resource [1] A B C D E 8 7 6 5 4 3 None E D E 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 302 succession

A AB B BC C CD Resource [2] D DE E Resource [1] Random Resource Supply A B C D E 8 7 6 5 4 3 2 1 A AB B BC C CD Resource [2] D A DE B C None E D E 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 302 succession

A AB B BC C CD Resource [2] D DE E Resource [1] Positively Correlated Resources A B C D E 8 7 6 5 4 3 2 1 A AB B BC C CD Resource [2] D A DE B C None E D E 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 302 succession

A AB B BC C CD Resource [2] D DE E Resource [1] Negatively Correlated Resources A B C D E 8 7 6 5 4 3 2 1 A AB B BC C CD Resource [2] D A DE B C None E D E 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 302 succession

A AB B BC C Resource [Light] CD D DE E Resource [Nitrogen] PRIMARY SUCCESSION A B C D E 8 7 6 5 4 3 2 1 A AB B BC C CD Resource [Light] D A DE B C D E E 0 1 2 3 4 5 6 7 8 9 10 Resource [Nitrogen] Biol 302 succession

A AB B BC C Resource [Light] CD D DE E Resource [Nitrogen] SECONDARY SUCCESSION A B C D E 8 7 6 5 4 3 2 1 A AB B BC Poor soil Rich soil C CD Resource [Light] D A DE B C D E E 0 1 2 3 4 5 6 7 8 9 10 Resource [Nitrogen] Biol 302 succession

Resource [Light] Resource [Nitrogen] Black Oak & Aspen 8 7 6 5 4 3 2 1 Aspen Black Oak Red Oak & Black Oak Red Oak White Oak & Red Oak Resource [Light] White Oak Sugar Maple & White Oak Sugar Maple 0 1 2 3 4 5 6 7 8 9 10 Resource [Nitrogen] Biol 302 succession

1 2 Resource [Light] 4 Resource [Nitrogen] DIVERSITY A B C D E 8 7 6 5 3 2 1 1 2 Resource [Light] A 4 B C D E 0 1 2 3 4 5 6 7 8 9 10 Resource [Nitrogen] Biol 302 succession

                                                                                                                                                TILMAN THE END Biol 302 succession

Studied trees in a New Hampshire forest FORCIER, Keith Studied trees in a New Hampshire forest Trees with dbh <2 cm (400 plots) 90% of canopy: Sugar maple American beech Yellow birch Biol 302 succession

% plots with at least 1 seedling SPECIES Density (#/m2) (dmin/dmax ) x 100 % plots with at least 1 seedling Mass/ind (mg) Yellow birch 21.3 2 92 8 Sugar maple 10 57 73 268 Beech 3.9 66 55 569 Biol 302 succession

Number of cohort alive at beginning of interval Age interval Yellow birch Sugar maple Beech 0-1 1-2 2-3 3-4 4-5 5-6 6-7 7-8 8-9 9-10 1000 70 <30 583 317 225 166 118 84 54 48 42 410 262 188 138 121 110 92 87 83 Biol 302 succession

CANOPY SEEDLINGS SAPLINGS < 0.5m tall 0.5 – 2 m tall Yellow birch Sugar maple Beech + + 0 - ++ Seed - Sprouts + Biol 302 succession

CLIMAX MICROSUCCESSION Beech (sprouts) Beech (seed) MINOR DISTURBANCE Sugar Maple Yellow birch CATASTROPHIC DISTURBANCE Successional communities Biol 302 succession