LECTURE18 Human Disruption and Ecological Restoration LECtUREl8 Humanimas luman Disruption and Ecological Restoration The ways of human disruption of ecosystems Over-hunting, overharvesting, overgrazing etc Cultural reasons Introduction of exotic Urbanization Change of land Simplifying ecosystems In modifying natural ecosystem for our use, we usually simplify them: in the case of forests and woodlands- into monoculture We spend a lot of time, energy, and money trying to protect monocul tures from continual inv asion by unwanted species, which we call weeds if they are plants, pests if they are insects or other animals, and pathogens if they are fungi, viruses or disease-causing bacteria. Often species undergo natural selection; a process illustrating Garret Hard in's first law of eco logy: "We can never do merely one thing. Any intrusion into nature has multiple effects, many of them unpredictable because of our limit derstand ing of how ature works Our actions should take into account the second law of ecology, or princ iple of connectedness: "Everything is connected to and intermingled with everything else", we are all in it together. There is no independence in nature Need for ecological restoration More than a century of severe habitat alteration has changed our forests and ecosystems to such an extent that they can no longer heal themselves Restoration is a multi-faceted discipline, ranging from hands-on work to theory, covering everything in the entire ecosystem"from the smallest insects all the Need for ecological restoration The motivations for ecological restoration range across ideas such biodiversity los research into the functioning of ecosystems compliance with public mandate The concept of restoration is simple-choose an ecosystem to emulate and try to recreate it in a chosen area But ecosystems are dynamic entities which vary not only in space but also in time Understanding ecological restoration 1: is protecting or managing the natural environment to maintain the beauty, interest, biodiversity, and other intrinsic values of the natural world 2: establishing a balance between our own species and the rest of the biosphere The two aspects are interrelated Examples of Species Interaction Process- Some grasses that grow in open areas form dense mats that prevent seeds of trees from reaching the soil and germ inate(Tai Later successional species cannot germinate or obtain light, water nutrient Examples of Species Interaction Ecological restoration is an activ ity at which everyone wins: when successful, we are rewarded by having returned a fragment of an ecosystem to its former state; when we fail, we learn a lot about how ecosystems work, provided we are able to determine why the failure occurred Examples of Species Interaction The success of ecological restoration can be judged by five criteria: utrient retention: and Biotic interactions Species Interaction Sustainability; is the reconstructed community capable of perpetuating itself? Or can it be sustained only if managed by people? Species Interaction Invasibility; does the reconstruction yields a community that resists invasions by new species?LECTURE18 Human Disruption and Ecological Restoration 1 LECTURE18 Human Disruption and Ecological Restoration Human impacts The ways of human disruption of ecosystems: -Over-hunting, overharvesting, overgrazing etc. -Deforestation, Pollution, Cultural reasons. Introduction of exotic species, Development, Urbanization, Change of land use, Simplifying ecosystems: In modifying natural ecosystems for our use, we usually simplify them; in the case of forests and woodlands – into monoculture. We spend a lot of time, energy, and money trying to protect monocultures from continual invasion by unwanted pioneer species, which we call weeds if they are plants, pests if they are insects or other animals, and pathogens if they are fungi, viruses or disease-causing bacteria. Often species undergo natural selection; a process illustrating Garret Hardin’s first law of ecology: “We can never do merely one thing”. Any intrusion into nature has multiple effects, many of them unpredictable because of our limited understanding of how nature works. Our actions should take into account the second law of ecology, or principle of connectedness: “Everything is connected to and intermingled with everything else”; we are all in it together. There is no independence in nature. Need for ecological restoration More than a century of severe habitat alteration has changed our forests and ecosystems to such an extent that they can no longer heal themselves. Restoration is a multi-faceted discipline, ranging from hands-on work to theory, covering everything in the entire "ecosystem" from the smallest insects all the way up to us as responsible humans. Need for ecological restoration The motivations for ecological restoration range across ideas such as biodiversity loss; research into the functioning of ecosystems; compliance with public mandates The concept of restoration is simple-choose an ecosystem to emulate and try to recreate it in a chosen area But ecosystems are dynamic entities which vary not only in space but also in time Understanding ecological restoration 1: is protecting or managing the natural environment to maintain the beauty, interest, biodiversity, and other intrinsic valu es of the natural world 2: establishing a balance between our own species and the rest of the biosphere. The two aspects are interrelated! Examples of Species Interaction Process - Some grasses that grow in open areas form dense mats that prevent seeds of trees from reaching the soil and germinate (Tai Mo Shan) Later successional species cannot germinate or obtain light, water & nutrient Examples of Species Interaction Ecological restoration is an activity at which everyone wins: when successful, we are rewarded by having returned a fragment of an ecosystem to its former state; when we fail, we learn a lot about how ecosystems work, provided we are able to determine why the failure occurred. Examples of Species Interaction The success of ecological restoration can be judged by five criteria: Sustainability; Invasibility; Productivity; Nutrient retention; and Biotic interactions Species Interaction Sustainability; is the reconstructed community capable of perpetuating itself? Or can it be sustained only if managed by people? Species Interaction Invasibility; does the reconstruction yields a community that resists invasions by new species? Species Interaction