© 2007, John Wiley and Sons, Inc. Physical Geography by Alan Arbogast Chapter 10 Plant Geography Lawrence McGlinn Department of Geography State University of New York - New Paltz

© 2007, John Wiley and Sons, Inc. Photosynthesis Solar radiation converted to chemical energy 6H 2 O + 6CO 2 + light energy = C 6 H 12 O 6 + 6O 2 Water + Carbon Dioxide + Light Energy = Glucose + Oxygen Produces almost all oxygen in Earth’s atmosphere

© 2007, John Wiley and Sons, Inc. Ecosystem Essentials Ecosystem – a self-sustaining association of living plants and animals and their nonliving environment Ecology – study of relationships between organisms and their environment and among various ecosystems Biogeography – study of the distribution of plants and animals

© 2007, John Wiley and Sons, Inc. Ecosystem Components and Cycles Communities - a biotic subdivision within an ecosystem; formed by interactions among populations of living plants and animals Habitat – type of environment where an organism resides or is biologically adapted to live Niche – the function or occupation of a life form in a community Competitive exclusion principle – no 2 species can occupy the same niche in a stable community

© 2007, John Wiley and Sons, Inc. Communities Symbiotic – 2 or more species exist together in an overlapping relationship Mutualistic – when each organism benefits and is sustained Parasitic – one organism benefits at the expense of another

© 2007, John Wiley and Sons, Inc. Local & Regional Influences on Vegetation Slope & Aspect Vertical Zonation Plant Succession Riparian Zones

© 2007, John Wiley and Sons, Inc. Slope & Aspect Slope – degree of steepness of an area Steep slopes have drier, thinner soils, less nutrients available Aspect – orientation of slope (N, S, E, W) Insolation intensity depends on aspect Slope facing sun warmer & drier Trees more common on slope away from sun Grasses & shrubs more common facing sun

© 2007, John Wiley and Sons, Inc. Slope & Aspect

© 2007, John Wiley and Sons, Inc. Vertical Zonation Change in vegetation based on elevation rather than latitude H climate Higher elevations cooler/colder than below Treeline is elevation above which conditions too harsh for trees – transition to alpine tundra Snow & ice above tundra

© 2007, John Wiley and Sons, Inc. Vertical Zonation

© 2007, John Wiley and Sons, Inc. Limiting Factors

© 2007, John Wiley and Sons, Inc. Riparian Zones Areas immediately adjacent to streams Greater moisture available for plants In arid or semi-arid regions, riparian zones support denser vegetation than surroundings Trees along a streambed in a semi-arid environment

© 2007, John Wiley and Sons, Inc. Plant Succession Occurs when newer communities (usually more complex) replace older communities of plants and animals (usually less complex) Natural changes in a biome over time – trend toward more complexity, Climax Vegetation Primary succession – on new sediments Secondary succession – in an area disturbed by fire or other catastrophic event

© 2007, John Wiley and Sons, Inc. Mount St. Helens

© 2007, John Wiley and Sons, Inc. Yellowstone Recovery

© 2007, John Wiley and Sons, Inc. Aquatic Succession

© 2007, John Wiley and Sons, Inc. Human Influence on Vegetation Patterns Deforestation – large tracts of land cleared of trees for commercial use or for agriculture 2.4% of world forest lost in 1990s (232 million acres) – most in tropical Africa & S. America Deforestation may intensify climate change as burning increases atmospheric CO 2 Massive deforestation in US, also – Upper Midwest and Northwest

© 2007, John Wiley and Sons, Inc. Deforestation Brazil – slash and burnWashington State – clear cut

© 2007, John Wiley and Sons, Inc. Agriculture in midlatitude grassland Only 1% to 4% of virgin prairie left in Great Plains The rest has been developed or used for intensive agriculture Overgrazing – too many sheep or cattle on too little land – vegetation is stripped, slow to come back – weeds establish in bare areas & erosion Human Influence on Vegetation Patterns