Lecture 04 - 02 Feb.doc

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Environmental Science
Environmental Science 1021F/G
Christie Stewart

ES1021G Lecture 4 – February 5, 2012 Biomes, Ecoregions and Ecozones (Freedman Chapter 8) Earth’s major biomes and their characteristics • A biome is a geographically extensive ecosystem, occurring wherever environmental conditions are suitable for its development (climatic conditions –ex. rainfall) • Biomes are characterized/identified by their dominant life forms; not by the species that occur there. E.g. forest biomes are characterized by an abundance of trees • At far-flung parts of biomes, different species may dominate the ecosystem – boreal forest ecosystem, at the northern border has different species then the southern border. Species may not be similar to each other, but have the same function • They may not even be closely related, but are similar in form and function because of convergent evolution Temperate – direct seasonality UWO campus in in temperate deciduous)  Boreal forest – coniferous trees, compared to temperate deciduous forests that lose their leaves in the fall ES1021F Lecture 4 – October 5, 2011  Tundra – near arctic environment, low vegetation across many kinds of species  Desert different from savanna – desert is short grasses, dry; while savanna think africa Very complex zonation of biomes – not only across land, but zonation can also occur as you increase in elevation above sea level. • The occurrence of biomes is determined by the environmental regime in which they develop o Terrestrial biomes are primarily influenced by temperature and precipitation o Freshwater biomes are mostly affected by nutrient availability, water transparency ( how deep can sunlight penetrate water), and depth (Erie is more susceptible to eutrophication because it is not as deep, so it heats up faster, causing algal blooms) o Marine biomes are affected by nutrients and physical oceanography ES1021G Lecture 4 – February 5, 2012 ^ label it exam question – how the terrestrial biomes are zoned according to mean annual temp. and precip. levels Major terrestrial biomes Tundra – vegetation of short stature, occurring at high latitude (arctic) and high altitude (alpine)- short grasses, small plants Boreal forest – northern subarctic (below latitudes of arctic) forest, usually dominated by coniferous trees Montane forest – a subalpine analogue of the boreal (higher altitudes, similar to boreal, but altitudes are different) – lower down mountain then alpine tundra Temperate forest – angiosperm-dominated forest (trees that flower) of intermediate latitudes (seasonality) – can contain coniferous trees as well as deciduous that have a distinct flower or seed Temperate rainforest – old-growth coniferous forest in a high-rainfall climate (such high rainfall that no longer have flowering trees) Temperate grassland – short-, mixed-, and tall-grass prairie types are limited by soil moisture (grasslands have deep soils, good for growing crops) Desert – sparsely vegetated because of dry conditions (short plants, or plants that have adapted to low precip. areas)- lowest biodiversity (even lower then tundra because tundra has soil where microorganisms can grow, while dessert is sandy) Tropical forest – various kinds of low-latitude forests in a warm, humid climate and supporting extremely rich biodiversity (highest biodiversity of all terrestrial biomes) Freshwater biomes (EXAM Q) (not as extreme ends of the spectrum as terrestrial because water is more stable then air, so enviro can only change so much) Lentic – lakes and ponds Lotic – rivers and streams Wetlands (or mires) – shallow, continuously or seasonally wet habitats (waterlogged- water table very high) [in between terrestrial and freshwater biomes, so factors that affect both kinds of biomes effect wetlands] o Marsh – highly productive and dominated by reed, cat-tail, bulrush, or other tall graminoids (high level of biomass – productive ecosystem) o Swamp – productive and dominated by tall shrubs or trees (trees here have adapted by keeping some of their rots above water to allow for aeration) ES1021F Lecture 4 – October 5, 2011 o Bog – unproductive and dominated by peat mosses (not as much nutrient content in the soil) o Fen – moderately productive and dominated by sedges and mosses (sedges are grass-like, but are not as tall as other grasses so don’t require as much nutrients) o Open-water wetland – moderately productive and dominated by aquatic plants (looks more like a pond with marginal vegetation) Marine biomes Open ocean – deep waters and highly unproductive – a marine desert (least bio diverse/ productive part of the ocean- even if phytoplankton are present) Continental Shelf Waters – moderate depths (up to several hundred metres) and moderate fertility and productivity Persistent Upwellings – regionds of high fertility and high productivity (near coastal zones, where there are temporary high levels of nutrients across all levels of biodiversity so species converge on one area) Estuaries – semi-enclosed coastal ecosystems with high productivity (where rivers flow into oceans, large, flat areas, semi enclosed coastal – because of water flow in both directions, often very important migration site) Seashores – productive intertidal and shallow subtidal ecotonal habitats occurring between true terrestrial and marine ones (some creatures are under the sand, and will emerge when tide is high/low, occur in subtidal and ecotidal zones, so species from either terrestrial or marine ecosystems live here) Coral reefs – infertile but highly productive and biodiverse tropical ecosystems (many mutualistic species, photosynthetic creatures living in the corals given them colours) Human-dominated ecosystems (almost considered another kind of biome) Urban-industrial techno-ecosystems – an anthropogenic complex of urbanized areas with few natural values and dominated by buildings, businesses, factories, and other infrastructure of urban civilization Rural techno-ecosystems – rural anthropogenic ecosystems consisting of the extensive infrastructure of society, such as transportation corridors and areas where natural resources are being extracted and processed Agroecosystems – regions where the major land-use is the growing of crops in agriculture and forestry ES1021G Lecture 4 – February 5, 2012 Ecozones (biomes- characterized by dominant life form) Ecoregions and ecozones are large landscapes (or seascapes) that support distinct groupings of species and their ecological communities Unlike biomes, their identity is strongly influenced by the specific biodiversity they support (i.e., by the particular species that occur in them), and also by their climate, physical landforms, and other aspects of geography There are hundreds of global ecoregions (compared to tens of biomes) Canada’s ecozones (KNOW A FEW) Terrestrial Ecozones Arctic Cordillera (somewhat mountainous) Northern Arctic Southern Arctic Taiga Plains Taiga Shield Taiga Cordillera Atlantic Maritime ES1021F Lecture 4 – October 5, 2011 Mixedwood Plains (southern Ontario) Boreal Plains (more nutrients, deep soil) Boreal Shield (on granite, shallow soil) Prairies Boreal Cordillera Pacific Maritime Montane Cordillera Hudson Plains Marine Ecozones Pacific Marine Arctic Archipelago Marine Northwest Atlantic Marine Atlantic Marine Arctic Basin Marine Canadian ecozones intergrade with those identified more broadly for North America. Distributions of species and ecological communities has little to do with those of political boundaries (research at ecozone boundries occurs across borders) Ecological research and biological conservation have a pervasive ecoregional context ES1021G Lecture 4 – February 5, 2012 ES1021F Lecture 4 – October 5, 2011 ES1021G Lecture 4 – February 5, 2012 ECOLOGY (Freedman Chapter 9) Ecology Ecology is the study of the relationships of organisms and their environment It is a core subject area of environmental science • Humans have unique and powerful capabilities, but are nevertheless dependent on the environment to supply all vital resources • The sustainability of the human economy is fundamentally an ecological issue Ecology
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