1、Human Impact on Resources and Ecosystems HIT Environmental Science Wang Xiuheng 2008What did we do?Human species exploit mineral resources and use natural ecosystem They are altered We success because we have ability to change our surroundings But Human-Altered does not equate to“Better”HIT Environm
2、ental Science Wang Xiuheng 2008Why does ecosystem matter?All life on earth,including human life,relies on Ecosystem services clean air,clean water renewable resources,etc For the first time in history,human actions are influencing ecosystems at a global scale.The consequences for ecosystem services
3、are poorly understood HIT Environmental Science Wang Xiuheng 2008Some“ecosystem services”purification of air and water mitigation of droughts and floods generation and preservation of soils and their fertility detoxification and decomposition of wastes pollination of crops and natural vegetation dis
4、persal of seeds cycling and movement of nutrients.How much can we degrade an ecosystem,and still receive these services?HIT Environmental Science Wang Xiuheng 2008Pollution Pollution-Anything released into the environment that affects an organisms survival and reproduction.Human people produce in la
5、rge enough quantities that it interferes with our health or well-being.Old days:small pop.+simple manner=diluted natural waste,biodegradable Now:generated faster than it can be degraded.Forms of pollution,from health concerns to annoyance HIT Environmental Science Wang Xiuheng 2008Several factors de
6、termine the impact of a society on natural resources.Impact of a pop.=Pop.Size/Area occupied x Degree of technological developmentPopulation sizePopulation densityDegree of technological Development always underestimated,purchase from other part,effect in distant places.HIT Environmental Science Wan
7、g Xiuheng 2008 Throughout history,humans have sought technological solutions to combat ecosystem degradation.Short-term solutions HIT Environmental Science Wang Xiuheng 2008Ecosystems Modified by Human Use Agricultural Rangelands Forests Aquatic Ecosystems Wilderness Species Extinction HIT Environme
8、ntal Science Wang Xiuheng 2008Agriculture Ecosystem 40%of the worlds land surface has been converted to cropland and permanent pasture.Remove original vegetation(what is it?),substituted by exotic domesticated crops and animals.Pop.Increase,more land or new tech?HIT Environmental Science Wang Xiuhen
9、g 2008Forests Ecosystems Forest service Climate modification Protector of watershed Deforestation For wood or land,lost of habitat or niche Expose the soil to increase erosion Tropical forest decrease 0.6%per year,temperate forest no significant change HIT Environmental Science Wang Xiuheng 2008 HIT
10、 Environmental Science Wang Xiuheng 2008Tropical deforestationThe loss of tropical rain forest creates local environmental problem of enormous magnitude,but for the worlds people the impacts,such as climate change,are long-term.HIT Environmental Science Wang Xiuheng 2008Forest management Clear cutti
11、ng vs.patch-work clear cutting Reforestation Lumber company:fast growing hybrid trees plantation,only economic value.Exotic No diversity HIT Environmental Science Wang Xiuheng 2008Rangeland Ecosystem From arid and semiarid lands support grasses or shrubs Domesticated animals,exotic species Selective
12、 eating plant soecies Native animals Overgrazing-desertification HIT Environmental Science Wang Xiuheng 2008 HIT Environmental Science Wang Xiuheng 2008Desertification土壤荒漠化土壤荒漠化Overgrazing and miss-farming convert arid and semiarid area to deserts.The loss of vegetation increase erosion by wind and
13、water.HIT Environmental Science Wang Xiuheng 2008Extinction 500 million to 5-10 million,98%extinction Natural selection,mostly to be extinct:Low pop.Density Found in small area Specialized niche Low reproductive rate HIT Environmental Science Wang Xiuheng 2008Human Accelerated Extinction Food prey s
14、pecies Ornament animal skin,ivory Pest tiger,wolf Habitat alteration Question?Why worry?HIT Environmental Science Wang Xiuheng 2008 HIT Environmental Science Wang Xiuheng 2008Human Impacts on Marine Systems few systems can now be considered natural-all have been modified,even the deep oceans human a
15、ctivity has changed marine communities in 5 major ways global climate change over-fishing of marine organisms invasions of exotic species chemical pollution and eutrophication loss or alterations of physical habitats HIT Environmental Science Wang Xiuheng 2008Over-Fishing fisheries exploitation chan
16、ges marine ecosystems more rapidly and over large scales than most other effects leads to changes in:distribution and abundance of species body size(size for reproduction)diversity of organisms in system dynamics of food webs(loss of predators)HIT Environmental Science Wang Xiuheng 2008 HIT Environm
17、ental Science Wang Xiuheng 2008Habitat Damage commercial fishing gears are often very destructive to habitats lost structure and features crucial for supporting fishery AND other components of the ecosystem in major regions of the world remote imagery shows every metre of seabed as being trawled mul
18、tiple times now seeing declines in recruitment of many species that need habitat as nursery areaFig.p.95鱼类食物链污染鱼类食物链污染Lip cancer of bullhead,in some tributaries of the Great Lakes,may reach 84%HIT Environmental Science Wang Xiuheng 2008Ecosystem Impacts fisheries often target top-level predators hig
19、h food and economic value(e.g.tuna)these species often have enormous impact on the rest of the ecosystem so-called KEYSTONE species historical removal from over-fishing now implicated in major ecosystem collapses including;coral reefs tropical seagrass beds kelp forests HIT Environmental Science Wan
20、g Xiuheng 2008aquaculture?Some Problems to be Solved clearing of coastal vegetation for fish farms(e.g.mangroves)pollution from fish farm runoff input of diseases and nutrients introduction of new genetic stock intowild population strong dependency on wild-caught fish in order to provide food for aq
21、uaculture HIT Environmental Science Wang Xiuheng 2008 HIT Environmental Science Wang Xiuheng 2008Cultural Eutrophication nutrients limiting to primary producers excessive loading of nutrients into waterbodies=cultural eutrophication human and animal waste runoff of fertilizers deposition of nitrogen
22、 from industrial releases,car exhausts and direct industrial discharges most control attempts-point source non-point source releases important amounts HIT Environmental Science Wang Xiuheng 2008Nuisance Algal Blooms increased loading of nutrients to estuaries enhances frequency and intensity of nuis
23、ance algal blooms increased algal production does not translate to high secondary production plants usually toxic or inedible no fish,consume algae HIT Environmental Science Wang Xiuheng 2008Fig.5.19 may involve toxic forms,release toxicant mortality of clams and fish anoxic in bottom waters,low DO-
24、dead zones on bottom of estuaries HIT Environmental Science Wang Xiuheng 2008 Natural Resource Structures and processes that human can use for their own purposes but not create.Sunlight,metal,scenery,soil.Renewable resources:can be formed or regenerated by natural process.ie.Soil,forest;but not inex
25、haustible Nonrenewable resources:fossil fuel and mineral.HIT Environmental Science Wang Xiuheng 2008Mineral Resource Formed millions of years ago Question Break:What is it?Include and Characteristic in China Uneven distribution through out the world international exchange Disproportionate share N.A.
26、5.1%world population,30%consumption HIT Environmental Science Wang Xiuheng 2008Costs Associated With Resource Exploitation Economic-monetary costs necessary to exploit the resource Energy-energy expended exploiting the resource Environmental-environmental effect of resource exploitation(often deferr
27、ed)HIT Environmental Science Wang Xiuheng 2008 Question What kind of env.cost?Mine tailing Vegetation Erosion Water wasting Ultimately converted to economic costs through buying energy and pollution controls.HIT Environmental Science Wang Xiuheng 2008Summary Pollution is anything that interferes wit
28、h health and well-being of living organisms.Grazing arid land for increased food production is short-sighted and destructive.We change natural ecosystems by replacing them with simplified ecosystems.As human population increases,we alter more ecosystems to feed ourselves.HIT Environmental Science Wang Xiuheng 2008Summary cont.Most productive areas of the ocean are also the most influenced by humans.Extinction is a consequence of a changing environment-and humans are influencing/changing almost all the worlds ecosystems.Exotic species can cause environmental harm.
