Ecology 15 Forests, Woodlands and Savanna

1. Ecology 15Forests, Woodlands and Savanna Ralph Kirby

2. Ecosystems where trees are dominant or codominantForests, Woodlands and Savannas • Forests • Where trees form a closed canopy • Most widespread • Requires enough moisture to support large trees • Specific bands – pole to equator • Coniferous • Temperate deciduous (warm and cool • Tropical

3. Warm aseasonal environment • Tropical Forest • Evergreen broadleaf trees • Seasonality • Dry tropical forest • Deciduous • Coniferous • Trees get smaller as seasonality increases • Actual Evapotranspiration rate

4. Productivity and Decomposition increase as the places get warmer and wetter • Note differences • Litterfall • Forest floor biomass • Turnover time for decomposition

5. Seasonality and Tropical Forest • Tropical Forest has been divided into various types • Boundary not clear • Not continuous • Broken by lack of moisture • Tropical Rain Forest • Lowland (<1000 m) • Mountain (>1000 m) • Cloud • Very high altitude • Swamp • Wet soils • Peat • Nutrient Poor • Tropical and Semi-tropical seasonal forests • 2 to 4 month droughts • Results in 30% loss of leaves • Fruits at the sta

6. Tropical Rain Forest • Very high diversity of microbial, plant and animal life • 10 square km • 1500 species of flowering plants • 750 species of trees • Richest – Malaysia – 7900 species • Stratification • Can be difficult to define • Crowns of emergent tree • Mop top trees • Conical top trees • Shrubs, young trees, tall herbs and ferns • Tree seedlings, low herbaceous plants and low ferns

7. Many plants use the trees for support • All shallow rooted • Mycorrhirae are important • Epiphytes • Niche • Stranglers • Whole tree • Climbers • Usually where disturbed • Continuous changes • Trees die • Trees fall • Gap appear and disappear • Stratification • Supports greater diversity of animal life • Above canopy group • Insectivorous and carnivorous birds and bats • Canopy group • Birds, fruit bats, mammals who eat leaves and fruit • Below canopy group • Flying mammals, birds and bats • Middle group • Squirrels and such that move between group and canopy • Forest Floor • Large herbivores and carnivores • Ground Group • Small insectivorous, herbivorous, carnivorous and omnivorous ammals

8. Deciduous Forest • Once covered most of Europe, China, North and South America • Largely cleared by humans • Remaining only semi natural with few exceptions • Two Types • Beech-Oak-Hornbeam • Oak-Hornbeam • More acid soils

9. Temperate Evergreen Forests in Subtropical areas • Australia • New Zealand • Patagonia • Temperate Deciduous Forest • Four strata in uneven aged stands • Even aged stands show poor separation • Canopy of dominant and codominant trees • Lower Tree Canopy • Shrub Layer • Ground layer • Animals inhabit various layers but less diversity than tropical forest • Light intensity in different areas varies with season • Spring gives most light to ground • Darkest for ground in midsummer • Microclimate variation • Highest temperatures in canopy • Humidity varies with season • Highest in summer • Higher during night than day

10. Coniferous Forests • Wide variety of environemnts • Mountains • Cool Temperate Regions • Simple Vertical Structures • Three types of crown • Straight cylindrical trunks with varying crown density • Scots pine • Spiral shaped • Douglas fir • Cedars • Deciduous conifers with pyramidal open crowns • Larch • Little vertical structure • Sharp reduction in light • Does not change • Some stratification for birds • Temperature variation • Changes with type of forest • Dominant in northern latitudes

11. Boreal Forest • Coniferous Forest that dominates northern latitudes • 11% of terrestial surface • Highly influenced by seasonal freezing and thawing • Permafrost in north • Wet in summer due to thawing • Tundra southwards • Forest-Tundra • Open boreal • Main boreal • Boreal-mixed forest • Simple Structure • Spiral spruces and firs • Open pines • Larch • Shallow roots • Fire important • Unique but simple animal community • Large herbivores • Ground birds • Some large carnviores • Herbivorous insects • Nesting ground of many neotropical and tropical birds

12. Changes in Environment affect Forests • High results in change from deciduous to coniferous • Reduced soil moisture gives rise to woodlands in temperate regions • Increased diversity of habitats and species • Reduced soil moistures gives rise to savannas in tropics • High biomass of grasses • Still lots of trees but spread out • Driven by seasonality • Unique herbivores

13. Grassland, Shrubland, Desert and Tundra • Decrease in available water changes Forest to Grassland in Temperate zones • 250mm to 800mm of rain • Note difference between created and natural grasslands • Europe – stable • America – revert to forest • Grasslands vary • Tallgrass prairie • Near forest • Shortgrass prairie • Great plains of US • Desert grassland • 300-400 mm rain • Steppe • Asia • 500-600 mm rain • Pampas • South America • 450-900 mm rain • Veld • Southern Africa • 1500-2000 metres

14. Vertical structure of grassland changes with season • Various layers containing different plants • As plants grow out of winter • At the ground • Light decreases • Temperature decreases • Humidity increases • Wind decreases • Thatch accumulates • Slow decomposition • 3 to 4 years • Burning important • Removes thatch and mulch • As does grazing • Complex root systems • Half plant below ground

16. Natural and domestic grassland support a very wide diversity of life • Large ungulates • Example: bison in US • Eurasian too originally • Africa: Zebra, Rhino, etc • Productivity and nutrient cycling controlled by drought • Best >800mm rain and >15oC • All grassland have evolved under grazing pressure together with drought

17. Shrubland • Difficult to characterize • Created by man • Created by disturbance • Part of arid gradient • Shrubs have an advantage over trees in arid areas • Invest less energy above ground • Better moisture collection • Faster growth • Mediterranean Shrubland • Winter rainfall • Broad leaf shrubs • Dwarfed trees • Heathland • Cold type shrubland • Nutriant poor, especially nitrogen and phosphorus • Usually high altitude • Dry Type • Seasonal drought • Wet Type • Seasonal waterlogging • Animal Community • Small animals and ground birds • Distinct to region

18. Desert • Diverse set of ecosystem • Where evaporation exceeds rainfall • Semi deserts • 150 to 300 mm rain • True deserts • 70 to 150 mm rain • Extreme deserts • <70 mm rain • Simple physical structure • Moisture limits production • Plants and animals adapt to aridity • Limited plant and animal diversity

19. Tundra • Low precipitation • Low temperature • Permafrost • 100% cover and moist • Simple structure • Low diversity of plants and animals • Animals and plants well adapted • Simple structure • Productivity • Low temperature • Extreme seasonality • Also polar desert