Ecology & Earth Sciences: Growth, Sustainability, Systems, Hazards, Knowledge - Prof. Sasw, Study notes of Environmental Science

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Nee Dt ee ECOLOGY AND GEOLOGY  Exam review  Chapter 1 (1.2)  Five fundamental concepts  Exponential growth, doubling time, factors controlling population growth rate  Sustainability, definition, sustainable development  Systems, definition of open and close systems, input-output analysis, average residence time, environmental unity, uniformitarianism  Hazardous processes, hazard identification, risk perception, hazard mitigation  Scientific knowledge and values, hypotheses, theory  Chapter 2 (2.1-2.3, 2.6-2.7)  Components of the Earth system and interrelation  Different layers of the Earth  Internal processes, convection  Understanding the internal structure  Lithosphere and asthenosphere  Different types of plate boundaries, sea-floor spreading Ecology & Geology Linkage Ecology  Study of relationships between living things and their environments Environmental Geology  Study of geological processes and their effects on environment The linkage  complex linkages, varies at different scales Fundamental Ecology Terms  Species: a group of individuals capable of interbreeding  Population: a group of individuals of the same species living in the same area  Community: a group of the populations of different species living in the same area  Biota: all organisms living in an area or a region  Biosphere: the part of Earth where organisms exist and function  Habitat: where a species lives  Niche: how the species makes its living Species  Indigenous species: found in the area where they evolved  Exotic species: brought into an area or a region by humans, purposely or accidentally • e.g., acacia trees: imported from Australia to arid regions as windbreaks • Foxes introduced to Australia  Invasive species: exotic species compete with indigenous species and may displace them Ecosystem An ecological community and its surrounding environment in which the flows of energy and cycles of chemicals support the living community Characteristics of an ecosystem  Ecosystem functions  Rate of flow of energy  Rates of chemical transfer  Structure of an ecosystem  Community of organisms  Geologic environment  Changes in an ecosystem  Primary succession (e.g. volcanism adding new land surface)  Secondary succession (reestablishment of an ecosystem following a moderate disturbance) Types of Ecosystem  Natural indigenous: ecosystem as the result of completely natural evolutional processes, rarely exist  Human modified: the one modified by human use and interest, almost all the major ecosystems  Human constructed: man-made ecosystem for many different purposes at many sites, such as ponds, canals, wastewater treatment pools Geology & Biodiversity  Geology affects the overall environmental conditions of an ecosystem  Changes in topography, e.g., mountain building & slope movement  Plate tectonics and ecosystem barrier, e.g., North America & Europe tree diversity vs. mountain range distribution  Changes in climate: ice age, glaciation, and global warming Keystone Species  Keystone species: species exert strong community effects disproportionate to their abundance Wolves and stream ecology  Case study: wolf, elk, and mountain stream system in Yellowstone National Park  1960s to mid-1990s: elk overbrowsed the riparian vegetation and affected the stream ecosystem  late 1990s: reintroduced wolves that hunted elk and promoted the growth of riparian vegetation, water quality, and stream ecosystem Kelp forests and otters  Sea otters, urchins, and kelp  Kelp forests: three parts – rootlike holdfast, stem (stipe), and blades (leaves)  Holdfast attached to boulders or the rocky bottom, part of the active geological environment  Urchins fed on the holdfast of kelp  Sea otters restored and fed on urchins, kelp forests restored Factors to Increase Biodiversity  Favored geological environment  Moderate amount of disturbance – hazards creating or renewing habitats  Harsh environments for certain unique specialized species, increasing biodiversity at regional scale  Relatively constant environmental conditions, such as T, P, precipitation, and elevation  Highly modified biologically productive environment Factors to Reduce Biodiversity  Extreme geological environment  Extreme disturbances damage habitats  Limit the number of habitats and ecological niches at a local scale  Pollution and other stresses restricting the flow of energy and nutrients  Fragmentation of ecosystems by land use transformation  Intrusion of invasive exotic species  Habitat simplification (engineering structure) or migration barriers Case Study: Seawalls and Biodiversity Figure 4.13 Time Dimension: Human Time vs. Earth Time  Geological processes on Earth time scale  Human activities and expectations on human time scale  Need to operate with an appropriate environmental ethic  Need to make a “pact” with Earth to achieve a more compatible relationship  Disrespect and disregard resulting environmental degradation Reduce the Human Footprint  Human population reduction  More efficient use of resources  Better management of our waste  Better understanding of ecosystems  The importance of human-dominated ecosystems and other types of ecosystems