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EVS 430 Fall 2008 Dr. Rotenberg Review Sheet – Midterm Hi Tropical Environment Folks, Please use this review sheet as a check-list for terms and ideas that we’ve covered so far. Be sure to begin studying NOW! Remember, the exam will have some multiple choice, but the rest will be short-answer-essay questions that you will need to answer from this material. Good Luck and Happy Studying!! J.R. Where are the tropics – Forest map http://www.unep-wcmc.org Major Environmental Problems in Tropics Deforestation Cattle Ranching Overpopulation/Resettlement of People Mining Activity Mercury Pollution Timber Harvesting Economics Poverty, war, social inequality >> Environmental degradation Tropical Deforestation - definition Why Tropical Deforestation? Main reason = Economics Short-term profits over long-term gain without a foundation of sound economic and ecological policy. Economics and High Population growth result in a labor force increasing more rapidly than the economy >> Promotes deforestation Deforestation in Amazonia (Brazil) Extent of Deforestation Causes: Road building (BR-364 in Rondonia) Cattle Ranching Resettlement of People Mining Activity and Mercury Pollution Timber Harvesting Deforestation in Central America Extent of Deforestation For What? Pastureland, Cattle Ranching, Various agriculture, Monoculture plantations of pine, oil palms, rubber (More statistics on pp. 16-17 Schroth) Anthropogenic Change Deforestation from Space – satellite photos Effects of Deforestation Road building, Cattle Ranching, Resettlement of People, Mining Activity and Mercury Pollution, Timber Harvesting Forest Fragmentation, Loss of Biodiversity Regional and Global Climate Change, Introduced Species, Exploitation of Natural Environments, Hunting, Loss of Env. Services Deforestation in Brazil and the above (ie., road building, cattle ranching etc.) Economic Effects of Tropical Deforestation And money $$$ Ecological Effects of Habitat Fragmentation in the Tropics Biodiversity – Lower? Higher? Genetic diversity and endemic species, coadaptation Edge Effects How far into fragment? 50m? 100? 500m? (figure 2.2, p 40) Tropical Forest Types Lowland evergreen Forest, Semi-evergreen Forest, Seasonal Dry Forest, Montane Forests (Cloud Forest), Jungle – aka: disturbed, successional, secondary forest, Flooded Forest – Amazon Basin, Thornwoods, Mangroves Other Tropical Habitats: Savannas, Coral Reefs & Atolls, Tropical Oceans Tropical Climate Sunlight, Trade winds, Ocean Currents, El Niño, Seasonality Climatic variations – know why they occur Greatest annual energy input Least amount of annual variation Tropics and Global climate influence Seasons and Earth’s orbit and tilt Population Trends, Poverty, and Economics in the Tropics Population numbers Large cities Urban problems Poverty and Poverty rates Causes of Poverty Education Tourism Valuating the Global Environment Neoclassical Economists Ecological / Environmental Economists Ecosystem Valuation Harmful External Costs and Full-Cost Pricing Does Economic Growth Always Aid the Environment? Obstacles to Sustainable Economic Growth Ecology Basics Photosynthetic strategies Populations Intrinsic Rate of Increase (r) Carrying Capacity (K) Population Growth Models Exponential & Logistic growth Density-dependent/independent population control Competition Competitive Exclusion Predation Succession Theory of Island Biogeography “Islands in a sea of Pasture” Area Effects – size/area relationships Small vs. Large fragments Distance Effects Isolation of fragments – organisms with phobias Metapopulations Small isolated subpopulations – gene flow Tropical Terms Biodiversity – defined Structural diversity High Biodiversity Measured in number of species/hectare 1 hectare = 2.471 acres High Biodiversity - Examples Why does the tropics have so many species? Vegetative Complexity – layers Forest Structure Physiognomy = structure Floristics = species Bole = trunk Tropical Tree Characteristics Stature-Height, Buttresses and Prop Roots, Trunks and Crowns Crown Architecture Sympodial, Monopodial Leaf Growth Monolayered, Mulilayered Leaf Shape Simple – Compound, Leaflets, Palmate – Pinnate, Drip-tip, See Page 79 - figure 41 Flower Growth and Type Flower once/year, Cauliflory, Shape/type attracts pollinators- list EVS 430 Fall 2008 Dr. Rotenberg Fruit Growth and Type Inflorescence, Size, Seed dispersal by animals, Seed predation, Wind dispersal Special Plant types Epiphytes - Bromeliads, Orchids Lianas (Vines), Strangler Figs, Palms Physiognomy (Structure), Floristics, Species, Vegetative complexity, Light Gap How a Rainforest Functions – Productivity Productivity - defined Productivity is measured in Biomass Biomass –defined Gross primary productivity (GPP) - defined Net primary productivity (NPP) = GPP- R Tropical Productivity facts Rainforests are at least 2x as productive as northern coniferous forests. Rainforests produce approximately 50 billion tons of dry organic matter annually compared to about 15 bill tons for temperate forest! 46% of the worlds’ living terrestrial carbon is stored in rainforests. --- Biochemical cycling!! Productivity graph – compares most to least productive habitat types – Where are tropical habitats compared to others? Why is rainforest productivity high? Longer growing season Nearly constant temperature Frost-free Life history traits and surviving the winter. Productivity is high but poor soils Most tropical soils are nutrient-poor. Nutrients are stored in the biomass of plants and animals of the forest. Nutrients are efficiently conserved Nutrient/Chemical cycling Essential soil nutrients: Phosphorus, Nitrogen, Calcium, Magnesium, and Potassium Phosphorus and Nitrogen necessary in formation of nucleic acids (DNA/RNA). Magnesium essential component of chlorophyll molecule. READ pp. 48-49 Pathway of calcium atom. Water Cycling and effects Transpiration- defined Water stressed plants – dry season Various adaptations to reduce water loss Water effects Leaching, soil acidity and accumulation of H+ ions (more H+ means lower pH) How do tropical plants cope with poor nutrient soils? Where’s the nutrients necessary for the rainforest? -- living plant tissues (biomass) Tropical Soil Types EVS 430 Fall 2008 Ultisols, Oxisols, Alfisols What happens to tropical soils when the rainforest is cleared? Laterization, Soil fertility, Oligotrophic and Eutrophic soils Nitrogen fixation READ pp.55-56 on how legumes acquire gaseous nitrogen with the help of the bacteria Rhizobium Forest Restoration - El Eden Ecological Reserve, Mexico Mycorrhizal fungi experiment Primary vs. Secondary Forest Secondary Forests –ex: Tikal Forest READ about Successional plants pp.69-74 Movie: “Medicine Man” NOTES Dr. Rotenberg