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3 trees dependant on sand dunes Sand dunes 4  3 km ice ice ground caused to sink down Isostasy elastic rebounding from all ice...

3 trees dependant on sand dunes Sand dunes 4  3 km ice ice ground caused to sink down Isostasy elastic rebounding from all ice Sitting there 5 6 newer dunes > - dunes closer to Lake Huron 7 grasses established 8 Older ecosystem 9 Oak savanna ecosystem 10 1960’s: 3 million pines planted dominate the ecosystem 11 oak trees the being outcompeted by pine trees > - reach up grab light 12 Oak savannas are fire- dependent ecosystems fire ecosystem dep on > - after conduct burn Forest started to look more like the native forest before trees were pine planted. 13  perscribed burn ↓ 14  oak trees to fre adapted > - thick bark burns trees Il I pine > - paper bark vid of non-native gettrees - 15  See return of organisms > - love dead wood from perscribed burns Red-headed woodpecker (Melanerpes erythrocephalus) 16  plant does well after a burn Blue lupine (Lupinus perennis) 17 Fire suppression led to rare lupine and local extinction of butterflies18 blue lupin & food source Karner blue butterfly (Lycaeides melissa) 19 Mottled Duskywing (Erynnis martialis) 20 reintroduce on New Jersey Tea in plants recently burned area of Pinery 21 Mottled Duskywing (Erynnis martialis) 22 Successful conservation 23  Disturbance Disturbance: an event that causes destruction of some part of a community or ecosystem Succession is the community-level recovery that follows a disturbance Disturbance and succession vary in physical and temporal scales 24  Resilience and resistance If succession restores the original community, the system shows resilience Ex back. oak comes > - after burn it you If the system can avoid disturbance, it shows resistance (sometimes called tolerance) now ? threshold long average Community structure or function · When there is low intensity disturbance the ecosystem is fine disturbance > - extreme community changes FIGURE 10.1 * how intense are fires 25  Resilience and resistance If succession restores the original community, the system shows resilience If the system can avoid disturbance, it shows resistance (sometimes called tolerance) In spite of chestnut blight, Jack pine forests return after forests are resistant to fire… they are resilient ecological collapse forest comm exist. Still 26  Small-scale disturbances Small-scale disturbances often occur in an otherwise intact community Our text calls them “gap- phase disturbances” and “micro-disturbances” Examples: Microsuccession restores the community in the gap created – Death of a single tree by a fallen tree. (Shown here: – Small landsides A treefall creates a canopy Hardwood forest intrees gap and smaller southern show – Grazing by cattle Ontario.) competitive release FIGURE 10.2 27  Large-scale disturbances Large-scale disturbances affect entire community Our text calls them “stand-replacing disturbances” Examples: – Wildfire – Wind storms – Glaciation Fires belong to natural ecosystem dynamics in – Biological agents many forests, and organisms are often adapted to fire FIGURE 10.24 28  Frequency of disturbance Frequency of disturbance can be regular or unpredictable Tides, cold or dry seasons, spring floods are regular and predictable Wildfires can be regular - but unpredictable kindling a enough - f Volcanic explosions are Strike Tidal communities irregular and experience a twice-a-day unpredictable inundation with salt water FIGURE 10.6 29  Patterns of succession Community-level recovery often follows a sequence of community types, called seral stages ↳ stages that a community Seral stages together after undergoes there has been disturbance form a sere ↳ view of how an ecosystem will change A stable community develops, depending on environmental factors, species present, and Sedge meadow is a seral stage in succession after a stochastic factors beaver dam collapses 30  E Oak forest at communities Climax communities are units of Pinery co-adapted mature Oaks organisms that occur survive the fire tog in with time regularity and make continu up canopy and space grassy underlayer soil sandy Frederick Clements suggested that successions have a predictable end-point: climax communities & final Seral Stage - after disturbance - Community recovers Frederick Clements 31  Climax communities Henry Gleason argued that there is no no co-evolved communities predictable end-point to succession Henry Gleason 32  Climax communities Nevertheless, older ecosystems may develop and remain stable over long periods, and represent a kind of climax community The climax community concept is a useful one Henry Gleason Frederick Clements 33  A forest sere Initial seral stages: r-strategist plants and survivors Pioneer trees are fast-growing, shade-intolerant, with strong dispersal Shade-tolerant trees dominate over time FIGURE 10.8 34  Hydrosere Initial stage: a young lake or pond after glacial Oligotrophic melting Oligotrophic at first, sediment accumulates slowly Nutrients increase over time Eventually the entire lake may turn into a wetland, even a forest FIGURE 10.9 35  Lithosere Succession on bare rock Common after glacial retreat or volcanic activity Begins with algae, lichens, mosses Followed by grasses and later by shrubs Lichen-, moss-, and grass-covered rocks FIGURE 10.10 36  Psammosere Succession on sandy substrates, such as shores of lakes and oceans Moving substrate is a special stress for plants: this instability favours vegetative reproduction Succession on sand in Lake Pinery’s dune Superior Provincial Park, ecosystems are an Ontario. excellent example 37  Alternative stable states Alternative stable states: In some cases, end point of succession may be dissimilar to the original community Example: Under certain With many otters, kelp dominates conditions, sea urchins thrive and eat kelp, and barren ground dominates Dominance of kelp depends on the presence of the urchin, which depends on sea otters With few otters, many offers - a lot of predation on urchins a lot of help urchins dominate FIGURE 10.11 top-down 38  Facilitation model of succession the stage for later stages early stages set A predictable sequence of species occurs because earlier seral stages facilitate conditions for later stages Example: Lichens and Lichen and moss… mosses create a substrate for grasses, which create substrate for trees Nitrogen-fixing organisms help Nitrogen-requiring organisms to follow … followed by grass 39  Tolerance model of succession each predictable stage has particular tolerance for diff biotic and abiotic factors A predictable sequence of species occurs because species vary in their ability to utilize resources and tolerate certain conditions Example: colonizing species are displaced at later seral stages as they cease to be able to In an abandoned field tolerate new conditions vegetation becomes more shade-tolerant over time 40  Inhibition model diff stages stop later stages from occuring A predictable sequence of species occurs because early species prevent or delay the establishment of later species Example: tall and dense stands of pioneers prevent growth of other species (dense grasses preventing establishment Dense stands of of trees) Phragmites inhibit growth of other plants 41  Life history and succession Early successional stages are dominated by organisms adapted to disturbance Spatially unpredictable disturbance: species with good dispersal have an advantage Temporally unpredictable disturbance: species with long-lived seeds (seed bank) Dandelions have far- have an advantage dispersing seeds acorns sit 44 in seed bank  Seed bank Seed bank: an enduring population of seeds in the surface litter and soil Following disturbance, increase in light or nutrients stimulate germination Arable fields often have large seed banks Pin cherry and red raspberry seeds remain dormant for decades 45  Means of regeneration Plants reproduce either vegetatively or by seed Reproduction by seed has the advantage of Seed-based reproduction large numbers, good in sugar maple dispersal, and durability during cold or dry periods Vegetative reproduction is more dependable harsh Imp in winter - killed portion of plant that was above ground to Vegetative reproduction in sugar maple allow Vegetative growth would growth occur -> M 46 from of ollowing basal parts the plant that - sit there underneath  Advanced regeneration Many trees survive over years as small plants under a canopy of mature trees They start to grow when the canopy opens This enables rapid response to disturbance Young sugar maple treelets under a canopy of mature sugar maple 47  Serotiny Serotinous seeds stay for years on the plant Release is triggered by an environmental factor Example: Cones of jack pines open in the heat of a fire and the seeds are then shed Large numbers of even- aged jack pine seedlings emerge and recolonize Serotinous jack pine cones 48 NOTHING LEFT Primary succession complete annihilation of all of the organisms that were there before Primary succession follows severe disturbances Succession depends on organisms invading from elsewhere Examples: volcanic eruptions, mudslides, glacial retreat, rising land, bulldozing by APrimary successionvolcanic newly-formed on a scree humans island, slope indevoid of the Swiss life, Alps ready with for primarycenisia. Campanula succession 49  Glacial retreat FIGURE 16.1 50  Primary succession at Pinery Colonizing plants stabilize substrate Persistent plants occur when substrate is stable Process takes thousands of years FIGURE 10.21 51  Secondary succession Secondary succession follows moderate disturbances Succession depends on both surviving organisms (seed bank, underground organisms) and colonists Succession may be quicker Examples: – Fire Secondary succession – Abandoned fields through vegetative – Storm damage growth after a fire 52  Summary Disturbances are events that destroy parts of a community or larger ecosystem Succession can restore ecosystem, or produce a fundamentally different one Succession follows predictable seral stages in different types of ecosystems Primary succession follows major disturbances; secondary succession follows minor disturbances 54