Lecture 4

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Western University
Environmental Science
Environmental Science 1021F/G
Marnie Branfireun

ES1021F Lecture 4 – October 5, 2011 Previous date’s notes were also presented today. Biodiversity - Summary Biomes and Ecozones Earth’s major biomes and their characteristics A biome is a geographically extensive ecosystem, occurring wherever environmental conditions are suitable for its development Biomes are not characterized by their species – it is the dominant life forms that identify them At far-flung parts of biomes, different species may dominate the ecosystem They may not even be closely related, but are similar in form and function because of convergent evolution Earth’s major biomes () The occurrence of biomes is determined by the environmental regime in which they develop ES1021F Lecture 4 – October 5, 2011 Terrestrial biomes are primarily influenced by temperature and precipitation Freshwater biomes are mostly affected by nutrient availability, water transparency, and depth Marine ones biomes are affected by nutrients and physical oceanography Major terrestrial biomes: EXAM! !!! !!! !!! !! ^^^ Tundra – vegetation of short stature, occurring at high latitude (arctic) and high altitude (alpine) Boreal forest – northern subarctic forest, usually dominated by coniferous trees Montane forest – a subalpine analogue of the boreal (boreal forest but on mountain) Temperate forest – angiosperm-dominated forest deciduous trees of intermediate latitudes Temperate rainforest – old-growth coniferous forest in a high-rainfall climate ES1021F Lecture 4 – October 5, 2011 Temperate grassland – short-, mixed-, and tall-grass prairie types are limited by soil moisture Desert – sparsely vegetated because of dry conditions Tropical forest – various kinds of low-latitude forests in a warm, humid climate and supporting extremely rich biodiversity Earth’s major biomes () Freshwater biomes: Lentic – lakes and ponds, not flowing water, any water that isn’t moving around all the time Lotic – rivers and streams, moving fast, flowing quickly EXAM!!!!!!!!!! : Difference between lentic and lotic?! Or difference between lentic and lotic system? Wetlands (or mires) – shallow, continuously or seasonally wet habitats Land that is really wet…… Marsh – highly productive and dominated by reed, cat-tail, bulrush, or other tall graminoids Swamp – productive and dominated by tall shrubs or trees Bog – unproductive and dominated by peat mosses Fen – moderately productive and dominated by sedges and mosses Open-water wetland – moderately productive and dominated by aquatic plants Earth’s major biomes (productivity is governed by biomass/vegetation in a biome) EXAM!!!!!!: Difference between biomes and Eco zones? Marine biomes: The open ocean – deep waters and highly unproductive – a marine desert Continental Shelf Waters – moderate depths (up to several hundred metres) and moderate fertility and productivity Persistent upwellings – regionds of high fertility and high productivity Estuaries – semi-enclosed coastal ecosystems with high productivity Seashores – productive intertidal and shallow subtidal ecotonal habitats occurring between true terrestrial and marine ones Coral reefs – infertile but highly productive and biodiverse tropical ecosystems Earth’s major biomes () Human-dominated ecosystems: ES1021F Lecture 4 – October 5, 2011 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 Canada’s ecozones Ecoregions and ecozones are large landscapes or seascapes that support distinct groupings of naturally assembled 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 (see Figure 8.3) Canada’s ecozones () Terrestrial Ecozones ES1021F Lecture 4 – October 5, 2011 Arctic Cordillera Northern Arctic Southern Arctic Taiga Plains Taiga Shield Taiga Cordillera Atlantic Maritime Mixedwood Plains Boreal Plains Boreal Shield Prairies Boreal Cordillera Pacific Maritime Montane Cordillera Hudson Plains Canada’s ecozones () The Canadian ecozones intergrade with those identified more broadly for North America (Figure 8.4) ES1021F Lecture 4 – October 5, 2011 This highlights the fact that the distributions of species and ecological communities has little to do with those of political boundaries As a consequence, ecological research and biological conservation have a pervasive ecoregional context ES1021F Lecture 4 – October 5, 2011 ECOLOGY From Individuals to the Biosphere 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 () Ecology is studied at several hierarchical levels: ES1021F Lecture 4 – October 5, 2011 Individual organisms, which are discrete, genetically unique entities Populations, or groups of individuals of the same species that can potentially interbreed with each other Species, consisting of one or more interbreeding populations that, in aggregate, are reproductively isolated from other such groups Communities, consisting of populations of various species that co-occur at the same time and place Landscapes and seascapes, which are spatial integrations of various communities over large areas The biosphere, consisting of all life and ecosystems on Earth Species are adapted to different levels of stress in their habitats Many environmental influences are resources that organisms can exploit to achieve productivity and to reproduce themselves Others influences are stressors that constrain productivity and reproductive fitness, such as: Inadequate nutrients or toxic chemicals Disturbances Biological stressors such as competition, predation, or disease 1. Outline how species are adapted to diferent levels of stress () All species have evolved unique solutions to coping with environmental opportunities and constraints faced during their evolutionary history For the purposes of studying the diverse life histories of species, ecologists have reduced the complexity by identifying broader strategies 1. Outline how species are adapted to different levels of stress () One scheme pro
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