Succession

1. Succession IB Syllabus: 2.3.5 – 2.3.7 Ch. 8

2. Syllabus Statements • 2.1.6: Define the terms species, population, habitat, niche, community, ecosystem with reference to a named example • 2.6.5 – Describe the concept and process of succession in a named habitat • 2.6.6 – Explain the changes in energy flow, gross and net productivity, diversity and mineral cycling in different stages of succession • 2.6.7 – Describe the factors affecting the nature of climax communities

3. Vocabulary • Climax Community • Community • Evolution • K strategists • R strategists • Sere • Succession • Zonation

4. Community • A group of populations interacting in a particular area • The fish community of Ponce Inlet • The plant community of the scrub habitat

5. Communities Change • Ecological Succession: the gradual change in species composition of a given area over time • Species do change spatially within an area at a certain point in time, this is zonation not succession • 2 Types depending on start point • Primary succession: gradual establishment of biological communities on lifeless ground • Secondary succession: reestablishment of biotic communities in an area where they already existed

6. Zonation II • Horizontal bands or zones of animals and organisms • Vertical layers in a rainforest • Differing plant communities as you go up a mountain • Created by physical and biological factors • Change in these factors is called an environmental gradient • In a rocky intertidal zone these would be • Drying (tides), salinity, competition, grazing

12. So how could you measure changes in biota along an environmental gradient? • Biota = living organisms • Change in benthic (bottom) community of rocky intertidal with increased depth • Gradient in moisture or drying • Use modified quadrat method • run transect into deeper water • At set depths place quadrat and sample organisms • Do repeated transects along your sample area • Calculate differences in communities with depth

14. Primary Succession • Begins in area with no soil on land, no sediment in water • Cooled lava, bare rock from erosion, new ponds, roads • Must be soil present before producers consumers and decomposers can exist

15. Exposed rocks Lichens and mosses Balsam fir, paper birch, and white spruce climax community Jack pine, black spruce, and aspen Heath mat Small herbs and shrubs Time

16. Pioneer Communities • Lichens and Mosses • Survive on nutrients in dust and rock • Start soil formation • Trap small particles • Produce organic material - photosynthesis • Chemically weather the rock • Patches of soil form

17. Seral Stages: Early Successional Plant Species • Small perennial grasses and herbs colonize, wind blown seeds • Grow close to the ground • Est. large pop. quickly in harsh conditions • Short lived • Break down rock

18. Seral Stages: Mid to Late Successional Species • After 100’s of years soil deep enough • Moisture & nutrients • Also called Seral Community • Shrubs then trees colonize • Trees create shade • Shade tolerant species establish

19. Seral stages • A seral community (or sere) is an intermediate stage found in ecological succession in an ecosystem advancing towards its climax community. • An example of seral communities in secondary succession is a recently logged coniferous forest; • during the first two years, grasses, heaths and herbaceous plants such as fireweed will be abundant, • after a few more years shrubs will start to appear • about six to eight years after clearing, the area is likely to be crowded with young birches. • Each of these stages can be referred to as a seral community.

20. Climax community • Characterized by K-selected species • Determined by • climate in the area – temperature, weather patterns • Edaphic factors – saturated wet, mesic, arid • Climax community structure is in stable equilibrium for each area • Humans & other factors may maintain an equilibrium below climax • E.g. current warming trends make climax rainforest communities w/ softer wood, faster growing species

21. End Result = Complex Community • Complex community mix of well established trees shrubs and a few grasses • Disturbance may change the structure • Fire, Flood, Severe erosion, Tree cutting, Climate change, Grazing, habitat destruction • Natural or Human processes • Specific successional stage is dependent on the frequency of disturbance

22. Disturbance and Diversity • Disturbance = any change in conditions which disrupts ecosystem or community structure • Catastrophic or Gradual • Disturbance eliminates strong competitors allowing others a chance • Promotes diversity • Intermediate disturbance  greatest diversity

23. Species diversity 0 100 Percentage disturbance The intermediate disturbance hypothesis

24. Townsend et al, cited in Begon Harper & Townsend,  Ecology

25. Secondary Succession • Begins when natural community is disturbed BUT soil & sediment remains • Abandoned farms, burned forests, polluted streams • New vegetation can germinate from the seed bank • In both cases succession focuses on vegetation changes

27. Mature oak-hickory forest Young pine forest Shrubs Perennial weeds and grasses Annual weeds Time Succession of Abandoned Farmland

28. Heliconia Bracts Tropical Rainforest flower Newer flowers form at the bottom As flowers form they fill with water Support aquatic communities Newly formed bracts early succession Nutrients and organics build up Over time succession occurs Higher bracts have climax communities

29. What changes occur through Succession? • Diversity • Starts very low in harsh conditions few species tolerate – r selected species types • Middle succession mix of various species types – most diverse (role of disturbance) • Climax – k selected species strong competitors dominate • Mineral Cycling • Pioneer, physical breakdown & make organic, Later processing increase – cycles expand

30. 3. Gross productivity changes (total photosynthesis) • Pioneer = Low density of producers at first • Middle & climax = high  lots of producers and consumers 4. Net Productivity (G – R = N) • Pioneer = little respiration so Net is large  system is growing, biomass accumulating • Middle & climax = respiration increases dramatically  N approaches zero (P:R = 1) 5. Energy flow • # of trophic levels increases over time • Energy lost as heat increases with more transfers

31. Early Successional Species Rabbit Quail Ringneck pheasant Dove Bobolink Pocket gopher Midsuccessional Species Elk Moose Deer Ruffled grouse Snowshoe hare Bluebird Late Successional Species Turkey Martin Hammond’s flycatcher Gray squirrel Wilderness Species Grizzly bear Wolf Caribou Bighorn sheep California condor Great horned owl Ecological succession Overview of Successional Changes © 2004 Brooks/Cole – Thomson Learning

32. Factors in Succession • Facilitation • One species makes an area suitable for another in a different niche • Legumes add nitrogen so other plants thrive • Inhibition • Early species hinder establishment and growth of later species  more disturbance needed to continue • Allelopathy by plants is an example • Tolerance • Late successors not affected by earlier ones • Explains mixture of species in Climax Communities

33. Predictability of Succession • Generally predictable end of succession is a Climax community • Only real rules are Continuous change, Instability, and unpredictability • Ever changing mosaic of patches in different successional stages • No real progression to an end, rather we see a reflection of an ongoing battle for resources and reproductive advantage

35. Aquatic Succession

36. Ecological Stability & Sustainability • Maintained by constant dynamic change • Positive and Negative feedback systems • Community may change but you will still recognize it as a particular type of community • Inertia = The ability of a living system to resist disturbance • Constancy = the ability of a system or population to keep its numbers within limits imposed by resources • Resilience = the ability of a system to bounce back after a disturbance

37. Diversity vs. Stability • Once thought that higher diversity = more stability for a community or ecosystem • Recent studies by D. Tilman on grasslands suggest • More species  higher NPP  more stable • Population #’s for individual species in diverse ecosystems fluctuate more widely • Some level of diversity does provide insurance against disasters • Nature is in a continual state of change

38. The Precautionary Principle • Human disturbances are disrupting ecosystem processes • Our ignorance of long term effects means we should be cautious • Thus, “When there is considerable evidence that and activity threatens human and ecosystem health, we should take precautions to minimize harm, even if the effects are not fully known.” • Better safe than sorry…

39. Grizzly bear NORTH AMERICA St. Lawrence beluga whale Eastern cougar Humpback whale More than 60% of the Pacific Northwest coastal forest has been cut down Spotted owl Fish catch in the north-west Atlantic has fallen 42% since its peak in 1973 Black- footed ferret 40% of North America’s range and cropland has lost productivity Florida panther Chesapeake Bay is overfished and polluted California condor Manatee Kemp’s ridley turtle Much of Everglades National Park has dried out and lost 90% of its wading birds Hawaiian monk seal Golden toad Coral reef destruction Half of the forest in Honduras and Nicaragua has disappeared Every year 14,000 square kilometers of rain forest is destroyed in the Amazon Basin Columbia has lost one-third of its forest Mangroves cleared in Equador for shrimp ponds Black lion tamarin PACIFIC OCEAN SOUTH AMERICA Little of Brazil’s Atlantic forest remains ATLANTIC OCEAN Southern Chile’s rain forest is threatened Environmental degradation Vanishing biodiversity Endangered species 6.0 or more children per woman

40. Many parts of former Soviet Union are polluted with industrial and radio- active waste ASIA Poland is one of the world’s most polluted countries Central Asia from the Middle East to China has lost 72% of range and cropland Giant panda Imperial eagle EUROPE Japanese timber imports are responsible for much of the world’s tropical deforestation Area of Aral Sea has Shrunk 46% Snow leopard Mediterranean 640,000 square kilometers south of the Sahara have turned to desert since 1940 Saudi Arabia Deforestation in the Himalaya causes flooding in Bangladesh Asian elephant Liberia Oman Kouprey Eritrea AFRICA Mali Yemen 90% of the coral reefs are threatened in the Philippines. All virgin forest will be gone by 2010 India and Sri Lanka have almost no rain forest left Burkina Faso Niger Benin Ethiopia Chad Golden tamarin Sierra Leone Nigeria Togo Congo Rwanda Burundi Uganda Sao Tome Somalia In peninsular Malaysia almost all forests have been cut 68% of the Congo’s rain forest is slated for cleaning Queen Alexandra’s Birdwing butterfly Angola Indonesia’s coral reefs are threatened and mangrove forests have been cut in half Zambia Nail-tailed wallaby INDIAN OCEAN Aye-aye Fish catches in Southeast Atlantic have dropped by more than 50% since 1973 AUSTALIA Black rhinoceros Madagascar has lost 66% of its tropical forest Much of Australia’s range and cropland have turned to desert Blue whale A thinning of the ozone layer occurs over Antarctica during summer ANTARCTICA

42. Hydrosere • A hydrosere is simply a succession which starts in water. A wetland, which is a transitional area between open freshwater and dry land, provides a good example of this and is an excellent place to see several stages of a hydrosere at the same time. • In time, an area of open freshwater such as a lake, will naturally dry out, ultimately becoming woodland. During this process, a range of different habitats such as swamp and marsh will succeed each other. • This succession from open water to climax woodland is likely to take at least two hundred years (probably much longer). Some intermediate stages will last a shorter time than others. For instance, swamp may change to marsh within a decade or less. How long it takes will depend largely on the amount of siltation occurring. • http://www.countrysideinfo.co.uk/successn/hydro.htm

43. Hydrosere

45. Halosere • The term Halosere is an ecological term which describes succession in a saline environment. An example of a halosere would be a salt marsh. • In riverestuaries, large amounts of silt are deposited by the ebbing tides and inflowing rivers. • The earliest plant colonizers are algae and eel grass which can tolerate submergence by the tide for most of the 12-hour cycle and which trap mud, causing it to accumulate. Two other colonisers are salicornia and spartina which are halophytes -i.e. plants that can tolerate saline conditions. They grow on the inter-tidal mudflats with a maximum of 4 hours' and exposure to air every 12 hours. • Spartina has long roots enabling it to trap more mud than the initial conlonizing plants and salicornia, and so on. In most places this becomes dominant vegetation. The initial tidal flats receive new sediments daily, are waterlogged to the exclusion of oxygen, and have a high pH value. • The sward zone, in contrast, is inhabited by plants that can only tolerate a maximum of 4 hours submergence everyday (24 hours). The dominant species here are sea lavender and other numerous types of grasses.

47. Halosere

48. Xerosere • Xerosere is a plant succession which occurs in conditions limited by water availability or the different stages in a xerarch succession. • Xerarch succession of ecological communities originated in extremely dry situation such as sand deserts, sand dunes, salt deserts, rock deserts etc. • A xerosere may include lithoseres and psammoseres.

49. Psammoseres • In geography, a psammosere is a sand sere - an environment of sand substratum on which ecological succession occurs. • In a typical succession on a sea-coast psammosere, the organisms closest to the sea will be salt tolerant species such as littoralalgae and glasswort. Progressing inland the succession is likely to include meadow grass, sea purslane, and sea lavender eventually grading into a typical non-maritime terrestrial eco-system. • www.sanddunes.20m.com/Evolution%20.htm