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Zonation and Succession IB Syllabus: 2.4 Vocabulary Climax Community Community Evolution K strategists R strategists Sere Succession Zonation Community A group of populations interacting in a particular area The marine life of Hoi Ha Wan reserve The forests along Shing Mun Valley Communities Change Ecological Succession: the change of species composition for a specified area over time. 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 Zonation: the change of species composition spatially within at a certain point of time Zonation Horizontal bands or zones of animals and organisms Differing plant and animal communities as you go up a mountain Differing plant and sea life communities as you go deeper from shore. Created by abiotic and biotic factors Change in these factors is called an environmental gradient In a rocky intertidal zone these would be Exposure (tides), salinity, competition, hydraulic action Source: http://hoopmanscience.pbworks.com Altitudinal Zonation Occurs due to changes caused by altitude during an identified period of time. Every 100m in altitude = one degree temperature decrease. Drier air caused by cooler temperatures. Changes in biotic communities caused by abiotic factors. Measuring changes along an environmental gradient? 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 1. Primary Succession Begins in area with no soil on land, no sediment in water Cooled lava, bare rock from erosion, new ponds, roads Img source: http://w3.marietta.edu/~biol/biomes/images/succession/acadia2.jpg Exposed Lichens rocks and mosses Small herbs and shrubs Heath mat Time Jack pine, black spruce, and aspen Balsam fir, paper birch, and white spruce climax community Pioneer Communities Lichens and Mosses Survive on nutrients in dust and rock Start soil formation Trap small particles Produce organic material through photosynthesis Chemically weathers the rock Patches of soil form Exposed Lichens rocks and mosses Small herbs and shrubs Heath mat Time Jack pine, black spruce, and aspen Balsam fir, paper birch, and white spruce climax community Seral Stages: Early Successional Plant Species Small perennial grasses and herbs colonize, from wind blown seeds 1. Small plants grow close to the ground 2. R-strategists immigrate 3. Short lived sere 4. Break down of rock Exposed Lichens rocks and mosses Small herbs and shrubs Heath mat Time Jack pine, black spruce, and aspen Balsam fir, paper birch, and white spruce climax community Mid to Late Succession After 100’s of years, deep soil forms Holds moisture & nutrients 1. Shrubs then trees colonize 2. Trees create shade 3. Shade tolerant species establish 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 exhausted cropland in tropical rainforests. during the first two years, grasses, herbs and softwood saplings will be abundant After many more years the saplings will start to form a canopy and shade tolerant shrubs will start to develop. Eventually hardwood epiphites like ficus and banyan will develop in tandem with lianas to form a thick canopy. Each of these stages can be referred to as a seral community. Climax community Characterized by K-selected species Climax community structure is in stable equilibrium for each area 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 Specific successional stage is dependent on the frequency of disturbance Silviculture and intercrops may maintain the plagio-climax sere. 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 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 What changes occur through Succession? Diversity 1. 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 2. • Pioneer, physical breakdown & make organic, Later processing increase – cycles expand 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 Table 8-1 Ecosystem Characteristics at Immature and Mature Stages of Ecological Succession Characteristic Ecosystem Structure Plant size Species diversity Trophic structure Ecological niches Community organization (number of interconnecting links) Table 8-1 Page 158 Immature Ecosystem (Early Successional Stage) Immature Ecosystem (Late Successional Stage) Small Large Low High Mostly producers, few decomposers Mixture of producers, consumers, and decomposers Few, mostly generalized Many, mostly specialized Low High Ecosystem Function Biomass Net primary productivity Food chains and webs Low High High Low Simple, mostly plant with few decomposers herbivore Complex, dominated by decomposers Efficiency of nutrient recycling Low High Efficiency of energy use High Low Factors in Succession Facilitation 1. • One species makes an area suitable for another in a different niche • Legumes add nitrogen so other plants thrive Inhibition 2. • Early species hinder establishment and growth of later species more disturbance needed to continue • Allelopathy by plants is an example Tolerance 3. • Late successors not affected by earlier ones • Explains mixture of species in Climax Communities 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 Aquatic Succession 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 Resilience = the ability of a system to bounce back after a disturbance Grizzly bear NORTH AMERICA More than 60% of the Pacific Northwest coastal forest has been cut down 40% of North America’s range and cropland has lost productivity California condor Hawaiian monk seal Eastern cougar Spotted owl Blackfooted Florida ferret panther Mangroves cleared in Equador for shrimp ponds Endangered species 6.0 or more children per woman Fish catch in the north-west Atlantic has fallen 42% since its peak in 1973 Chesapeake Bay is overfished and polluted Golden toad Coral reef destruction Every year 14,000 square kilometers of rain forest is destroyed in the Amazon Basin Columbia has lost one-third of its forest PACIFIC OCEAN Vanishing biodiversity Humpback whale Manatee Much of Everglades National Park has dried out and lost 90% of its wading birds Kemp’s ridley turtle Half of the forest in Honduras and Nicaragua has disappeared Environmental degradation St. Lawrence beluga whale Black lion tamarin SOUTH AMERICA Southern Chile’s rain forest is threatened Little of Brazil’s Atlantic forest remains ATLANTIC OCEAN Poland is one of the world’s most polluted countries Imperial eagle 640,000 square kilometers south of the Sahara have turned to desert since 1940 EUROPE Mediterranean Many parts of former Soviet Union ASIA are polluted with industrial and radioactive waste Central Asia from the Middle East to China has lost 72% of range Giant and cropland panda Area of Aral Sea has Shrunk 46% Snow leopard Japanese timber imports are responsible for much of the world’s tropical deforestation Saudi Arabia Deforestation in the Himalaya Asian causes flooding in Bangladesh Liberia elephant Oman Kouprey Eritrea Mali AFRICA Yemen 90% of the coral reefs India and are threatened in the Burkina Niger Ethiopia Sri Lanka Philippines. All virgin Faso Benin Chad Golden have almost forest will be gone Sierra tamarin no rain Nigeria by 2010 Leone forest left Togo Congo Uganda Sao Tome Rwanda Somalia In peninsular Malaysia Queen Alexandra’s 68% of the Burundi almost all forests have Birdwing butterfly Congo’s Angola been cut rain forest Indonesia’s is slated Zambia coral reefs are Nail-tailed for cleaning INDIAN OCEAN threatened wallaby and Aye-aye Fish catches in mangrove AUSTALIA Black Southeast Atlantic forests Madagascar has have dropped by more rhinoceros Much of have been lost 66% of its than 50% since 1973 Australia’s cut in half tropical forest range and cropland have turned to desert Blue whale A thinning of the ozone layer occurs over Antarctica during summer ANTARCTICA 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. Hydrosere 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 river estuaries, 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. Halosere 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. 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 littoral algae and glasswort. Progressing inland the succession is likely to include meadow grass, sea purslane, and sea lavender eventually grading into a typical nonmaritime terrestrial eco-system. www.sanddunes.20m.com/Evolution%20.htm