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Ecological Processes: The Planet's Life Support System

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1 Ecological Processes: The Planet's Life Support System
Environmental Sustainability Educational Resources prepared by Gregory A. Keoleian Associate Research Scientist, School of Natural Resources and Environment Co-Director, Center for Sustainable Systems University of Michigan

2 Contents Percent of Species at Risk of Extinction [slide 3]
Ecology Definition [slide 4] Ecosystem Definition [slide 5] Definition of the Precautionary Principle [slide 6] Ecosystem Services [slide 7-8] What are ecosystems worth [slide 9-14] Biosphere 2 [slide 15-16] Ecosystem threats [slide 17-18] Endangered Species [slide 19-20] Exotic Species [slide 21-26] Carrying Capacity, Population and Ecological Footprint [slide 27-30] Ecological Engineering [slide 31-32] Additional Resources [slide 33-34]

3 Source: Address and slide show, delivered by Edward O
Source: Address and slide show, delivered by Edward O. Wilson, Harvard University, April 28, 1998 U.S. Capitol Washington, DC At the present time, about 100,000 species of plants animals and microorganisms are known to be native to the United States. Of these, as the recent survey published by the Nature Conservancy from the best databases available shows, it is apparent that about 1% are extinct. I suspect it is more than that because it is hard to track all the rare species that may have gone extinct in earlier times. About 1% has gone extinct and 1/3 are in some degree of endangerment, much of it due to the continued removal of America’s Ancient Forests and other critical habitat. Now when you cut a forest, an Ancient Forest in particular, you are not just removing a lot of big trees and a few birds fluttering around in the canopy. You are removing or drastically imperiling a vast array of species even within a few square miles of you. The number of these species may go to tens of thousands. Many of them, the very smallest of them, are still unknown to science, and science has not yet discovered the key role undoubtedly played in the maintenance of that ecosystem, as in the case of fungi, microorganisms, and many of the insects. They have been a symbol in these habitats, literally over millions of years of evolution. They are exquisitely adapted to these habitats. That is how the balance has been maintained. That is a balance that has been severely affected by these new procedures of extensive lumbering that humanity has introduced.

4 Ecology Definition “Ecology is the scientific discipline that is concerned with the relationships between organisms and their past, present, and future environments.” Source: Ecological Society of America Ecology is the study of the relationships between living organisms, including humans, and their physical environment; it seeks to understand the vital connections between plants and animals and the world around them. These relationships include physiological responses of individuals, structure and dynamics of populations, interactions among species, organization of biological communities, and processing of energy and matter in ecosystems.

5 Other Definitions Ecosystem Biodiversity
any geographic area that includes all of the organisms and nonliving parts of their physical environment. Biodiversity Biological diversity, or biodiversity for short, refers to the variety of life forms at all levels of organization, from the molecular to the landscape level. Source: and Issues in Ecology, "Ecosystem Services: Benefits Supplied to Human Societies by Natural Ecosystems, No. 2, Spring, 1997, Ecological Society of America. Available on ESA’s web site at An ecosystem can be a natural wilderness area, a suburban lake or forest, or a heavily used area such as a city. The more natural an ecosystem is, the more ecosystem services it provides. These include cleansing the water (wetlands and marshes) and air (forests), pollinating crops and other important plants (insects, birds, bats), and absorbing and detoxifying pollutants (soils and plants). Short for biological diversity, biodiversity includes all organisms, species, and populations; the genetic variation among these; and all their complex assemblages of communities and ecosystems. It also refers to the interrelatedness of genes, species, and ecosystems and their interactions with the environment. Usually three levels of biodiversity are discussed-genetic, species, and ecosystem diversity. Genetic diversity is all the different genes contained in all individual plants, animals, fungi, and microorganisms. It occurs within a species as well as between species. Species diversity is all the differences within and between populations of species, as well as between different species. Ecosystem diversity is all the different habitats, biological communities, and ecological processes, as well as variation within individualecosystems.

6 *Definition of the Precautionary Principle
Asserts there is a 'premium' on a cautious and conservative approach to human interventions in the natural environment where our understanding of the likely consequences is limited and there are threats of serious or irreversible damage to natural systems and processes. (As noted by Myers 1993 in Barbier, Burgess and Folke 1994, 172).

7 Ecosystems Services (1 of 2 slides)
moderate weather extremes and their impacts disperse seeds mitigate drought and floods protect people from the sun’s harmful ultraviolet rays cycle and move nutrients protect stream and river channels and coastal shores from erosion detoxify and decompose wastes Issues in Ecology, "Ecosystem Services: Benefits Supplied to Human Societies by Natural Ecosystems, No. 2, Spring, 1997, Ecological Society of America. Available on ESA’s web site at Many societies today have technological capabilities undreamed of in centuries past. Their citizens have such a global command of resources that even foods flown in fresh from all over the planet are taken for granted, and daily menus are decoupled from the limitations of regional growing seasons and soils. These developments have focused so much attention upon human-engineered and exotic sources of fulfillment that they divert attention from the local biological underpinnings that remain essential to economic prosperity and other aspects of our well-being. These biological underpinnings are encompassed in the phrase ecosystem services, which refers to a wide range of conditions and processes through which natural ecosystems, and the species that are part of them, help sustain and fulfill human life. These services maintain biodiversity and the production of ecosystem goods, such as seafood, wild game, forage, timber, biomass fuels, natural fibers, and many pharmaceuticals, industrial products, and their precursors. The harvest and trade of these goods represent important and familiar parts of the human economy. In addition to the production of goods, ecosystem services support life through (Holdren and Ehrlich 1974; Ehrlich and Ehrlich 1981).

8 Ecosystems Services (2 of 2 slides)
control the vast majority of agricultural pests maintain biodiversity generate and preserve soils and renew their fertility partially stabilize climate purify the air and water regulate disease carrying organisms pollinate crops and natural vegetation

Natural ecosystems and the plants and animals within them provide humans with services that would be very difficult to duplicate. While it is often impossible to place an accurate monetary amount on ecosystem services, we can calculate some of the financial values. Many of these services are performed seemingly for "free", yet are worth many trillions of dollars, for example:

10 Flood Protection Much of the Mississippi River Valley’s natural flood protection services were destroyed when adjacent wetlands were drained and channels altered. As a result, the 1993 floods resulted in property damages estimated at twelve billion dollars partially from the inability of the Valley to lessen the impacts of the high volumes of water.

11 Source for Medicinal Products
Eighty percent of the world’s population relies upon natural medicinal products. Of the top 150 prescription drugs used in the U.S., 118 originate from natural sources: 74 percent from plants, 18 percent from fungi, 5 percent from bacteria, and 3 percent from one vertebrate (snake species). Of the top 10 prescription medicines, 9 originate from natural plant products.

12 Pollination Services Over 100,000 different animal species - including bats, bees, flies, moths, beetles, birds, and butterflies - provide free pollination services. One third of human food comes from plants pollinated by wild pollinators. The value of pollination services from wild pollinators in the U.S. alone is estimated at four to six billion dollars per year.

13 Pure Water Before it became overwhelmed by agricultural and sewage runoff, the watershed of the Catskill Mountains provided New York City with water ranked among the best in the Nation by Consumer Reports. When the water fell below quality standards, the City investigated what it would cost to install an artificial filtration plant. The estimated price tag for this new facility was six to eight billion dollars, plus annual operating costs of 300 million dollars - a high price to pay for what once was free. New York City decided instead to invest a fraction of that cost ($660M) in restoring the natural capital it had in the Catskill’s watershed. In 1997, the City raised an Environmental Bond Issue and is currently using the funds to purchase land and halt development in the watershed, to compensate property owners for development restrictions on their land, and to subsidize the improvement of septic systems.

14 Estimated Value Value of Ecosystem Services = $33 trillion
range: trillion 1.8 x Global GNP Majority of the value of these services is outside the market system source: Costanza, et al. Nature 1997 Abstract “The services of ecological systems and the natural capital stocks that produce them are critical to the functioning of the Earth’s life-support system. They contribute to human welfare, both directly and indirectly, and therefore represent part of the total economic value of the planet. We have estimated the current economic value of 17 ecosystem services for 16 biomes, based on published studies and a few original calculations. Fro the entire bioshpere, the value (most of which is outside the market) is estimated to be in the range of US $16-54 trillion per year, with an average of US $33 trillion per year. Because of the nature of the uncertainties, this must be considered a minimum estimate. Global gross national product total is around US$18 trillion per year” Nature, vol 387, 15 May 1997 p 253

15 Biosphere 2 Source:
The tremendous expense and difficulty of replicating lost ecosystem services is perhaps best illustrated by the results of the first Biosphere 2 "mission," in which eight people lived inside a 3.15-acre closed ecosystem for two years. The system featured agricultural land and replicas of several natural ecosystems such as forests and even a miniature ocean. In spite of an investment of more than $200 million in the design, construction, and operation of this model earth, it proved impossible to supply the material and physical needs of the eight Biospherians for the intended 2 years. Many unpleasant and unexpected problems arose, including a drop in atmospheric oxygen concentration to 14% (the level normally found at an elevation of 17,500 feet), high spikes in carbon dioxide concentrations, nitrous oxide concentrations high enough to impair the brain, an extremely high level of extinctions (including 19 of 25 vertebrate species and all pollinators brought into the enclosure, which would have ensured the eventual extinction of most of the plant species as well), overgrowth of aggressive vines and algal mats, and population explosions of crazy ants, cockroaches, and katydids. Even heroic personal efforts on the part of the Biospherians did not suffice to make the system viable and sustainable for either humans or many nonhuman species (Cohen and Tilman 1996).

16 Source:

17 Ecosystem services are severely threatened through:
growth in the scale of human enterprise (population size, per-capita consumption, and effects of technologies to produce goods for consumption) and a mismatch between short-term needs and long-term societal well-being. Issues in Ecology, "Ecosystem Services: Benefits Supplied to Human Societies by Natural Ecosystems, No. 2, Spring, 1997, Ecological Society of America. Available on ESA’s web site at

18 Human activities that disrupt, impair, or reengineer ecosystems:
runoff of pesticides, fertilizers, and animal wastes pollution of land, water, and air resources introduction of non-native species overharvesting fisheries destruction of wetlands erosion of soils deforestation urban sprawl Issues in Ecology, "Ecosystem Services: Benefits Supplied to Human Societies by Natural Ecosystems, No. 2, Spring, 1997, Ecological Society of America. Available on ESA’s web site at SUMMARY Human societies derive many essential goods from natural ecosystems, including seafood, game animals, fodder, fuelwood, timber, and pharmaceutical products. These goods represent important and familiar parts of the economy. What has been less appreciated until recently is that natural ecosystems also perform fundamental life-support services without which human civilizations would cease to thrive. These include the purification of air and water, detoxification and decomposition of wastes, regulation of climate, regeneration of soil fertility, and production and maintenance of biodiversity, from which key ingredients of our agricultural, pharmaceutical, and industrial enterprises are derived. This array of services is generated by a complex interplay of natural cycles powered by solar energy and operating across a wide range of space and time scales. The process of waste disposal, for example, involves the life cycles of bacteria as well as the planet-wide cycles of major chemical elements such as carbon and nitrogen. Such processes are worth many trillions of dollars annually. Yet because most of these benefits are not traded in economic markets, they carry no price tags that could alert society to changes in their supply or deterioration of underlying ecological systems that generate them. Because threats to these systems are increasing, there is a critical need for identification and monitoring of ecosystem services both locally and globally, and for the incorporation of their value into decision-making processes. Historically, the nature and value of Earth’s life support systems have largely been ignored until their disruption or loss highlighted their importance. For example, deforestation has belatedly revealed the critical role forests serve in regulating the water cycle -- in particular, in mitigating floods, droughts, the erosive forces of wind and rain, and silting of dams and irrigation canals. Today, escalating impacts of human activities on forests, wetlands, and other natural ecosystems imperil the delivery of such services. The primary threats are land use changes that cause losses in biodiversity as well as disruption of carbon, nitrogen, and other biogeochemical cycles; human-caused invasions of exotic species; releases of toxic substances; possible rapid climate change; and depletion of stratospheric ozone. Based on available scientific evidence, we are certain that: Ecosystem services are essential to civilization. Ecosystem services operate on such a grand scale and in such intricate and little-explored ways that most could not be replaced by technology. Human activities are already impairing the flow of ecosystem services on a large scale. If current trends continue, humanity will dramatically alter virtually all of Earth’s remaining natural ecosystems within a few decades. In addition, based on current scientific evidence, we are confident that: Many of the human activities that modify or destroy natural ecosystems may cause deterioration of ecological services whose value, in the long term, dwarfs the short-term economic benefits society gains from those activities. Considered globally, very large numbers of species and populations are required to sustain ecosystem services. The functioning of many ecosystems could be restored if appropriate actions were taken in time. We believe that land use and development policies should strive to achieve a balance between sustaining vital ecosystem services and pursuing the worthy short-term goals of economic development.

19 Endangered Species 735 U.S. species of plants are listed.
496 U.S. species of animals are listed. 11 U.S. species of plants are currently proposed for listing. 74 U.S. species of animals are currently proposed for listing. Source:

20 Endangered Florida panther
USFWS photo by John & Karen Hollingsworth

21 Exotic Species "Exotic" species—organisms introduced into habitats where they are not native are severe world-wide agents of habitat alteration and degradation. a major cause of biological diversity loss throughout the world, they are considered "biological pollutants." Source: Introducing species accidentally or intentionally, from one habitat into another, is risky business. Freed from predators, parasites, pathogens, and competitors that have kept their numbers in check, species introduced into new habitats often overrun their new home and crowd out native species. In the presence of enough food and a favorable environment, their numbers will explode. Once established, exotics rarely can be eliminated. Most species introductions are the work of humans. Some introductions, such as carp and purple loosestrife, are intentional and do unexpected damage. However, many exotic introductions are accidental. The species are carried in on animals, vehicles, ships, commerical goods, produce, and even clothing. Some exotic introductions are ecologically harmless and some are beneficial. Other exotic introductions are harmful to recreation and ecosystems. They have even caused the extinction of native species—especially those of confined habitats such as islands and aquatic ecosystems. The recent development of fast ocean freighters has greatly increased the risk of new exotics in the Great Lakes region. Ships take on ballast water in Europe for stability during the ocean crossing. This water is pumped out when the ships pick up their loads in Great Lakes ports. Because the ships make the crossing so much faster now, and harbors are often less polluted, more exotic species are likely to survive the journey and thrive in the new waters.

22 Invasive species threaten biodiversity, habitat quality, and ecosystem function.
second-most important threat to native species, behind habitat destruction contributed to the decline of 42% of U.S. endangered and threatened species. introduced species also present an ever-increasing threat to food and fiber production. In the United States, the economic costs of nonnative species invasions reach billions of dollars each year.

23 Sea lamprey on lake trout
Sea Lamprey (Petromyzon marinus ) are predaceous, eel-like fish native to the coastal regions of both sides of the Atlantic Ocean. They entered the Great Lakes through the Welland Canal about They contributed greatly to the decline of whitefish and lake trout in the Great Lakes. Source:

24 Lake trout with scar from sea lamprey

25 Zebra mussels washed up on beach
Source: Dreissena polymorpha Zebra mussels and a related species, the Quagga mussel, are small, fingernail-sized mussels native to the Caspian Sea region of Asia. They were discovered in Lake St. Clair near Detroit in Tolerant of a wide range of environmental conditions, zebra mussels have now spread to parts of all the Great Lakes, the Mississippi River, and are showing up in inland lakes. Zebra mussels clog water-intake systems of power plants and water treatment facilities, as well as irrigation systems, and the cooling systems of boat engines. They have severely reduced, and may eliminate native mussel species. Microscopic larvae may be carried in livewells or bilge water. Adults can attach to boats or boating equipment that sit in the water.

26 Source:
Lythrum salicaria Purple loosestrife is a wetland plant from Europe and Asia. It was introduced into the east coast of North America in the 1880s. First spreading along roads, canals, and drainage ditches, then later distributed as an ornamental, this exotic plant is in 40 states and all Canadian border provinces. Purple loosestrife invades marshes and lakeshores, replacing cattails and other wetland plants. The plant can form dense, impenetrable stands which are unsuitable as cover, food, or nesting sites for a wide range of native wetland animals including ducks, geese, rails, bitterns, muskrats, frogs, toads, and turtles. Many rare and endangered wetland plants and animals are also at risk. Likely means of spread: Seeds escape from gardens and nurseries into wetlands, lakes, and rivers. Once in aquatic systems, seeds are easily spread by moving water and wetland animals.

27 Carrying Capacity Maximum population size that a given area can sustain Estimate’s of the earth’s carrying capacity vary widely ranging from billion people (Cohen 1995) See Cohen, J. Science Vol 269 p 341

28 World Population Size: Estimates and Fertility Variants (billions)
UN Population Division projects (medium fertility scenario) that the world population will rise from 5.7 billion in 1995 to 9.7 billion persons in 2150. Low scenario = half a child lower than in medium scenario Medium scenario = fertility in all major areas stabilizes at replacement level around 2050 High = half a child higher than in medium scenario Source: United Nations Population Division, World Population Prospects: The 1998 Revision, forthcoming.

29 The Ecological Footprint is measured in "area units"
The Ecological Footprint is measured in "area units". One area unit is the equivalent of one hectare of world average productivity. This figure shows the size of the Ecological Footprints of seven regions of the world in The size of each box is proportional to the footprint of each region: the height of the bar is proportional to the region's average Ecological Footprint per person and the width of the bar is proportional to the population of the region. The Ecological Footprint of an average consumer in the industrialized world was about four times that of an average consumer in the lower income countries. Source: Living Planet Report 2000

30 Have we exceeded the Earth’s Carrying Capacity?
In 1996 there were 2.2 ha per person of biologically productive land on the planet a total of 12.6 billion hectares, covering 1/4 of the Earth’s surface 1.3 billion ha cropland 4.6 billion ha grazing land 3.3 billion ha forest land 3.3 billion ha fishing grounds 0.2 billion ha built-up land World average footprint was 2.85 ha per person Source: Living Planet Report 2000 UNEP, World Conservation Monitoring Centre/ Redefining Progress/ Centre for Sustainability Studies In 1996 there were 12.6 billion hectares of biologically productive land on the earth, covering roughly one quarter of the planet's surface. These consisted of 1.3 billion hectares of cropland, 4.6 billion hectares of grazing land, 3.3 billion hectares of forest land, 3.2 billion hectares of fishing grounds, and 0.2 billion hectares of built-up land. This amounts to 2.2 hectares for each of the world's 5.7 billion people in If we assume, for the sake of argument, that 10% of all biologically productive space should be left undisturbed for other species, the available space per person shrinks from 2.2 to 2.0 area units. In contrast, the world average footprint was 2.85 area units per person in This exceeds the existing biologically productive space per person by about 30%, or more if some space is reserved exclusively for other species. In other words, humanity's Ecological Footprint was at least 30% larger than the area available. This overshoot leads to a gradual depletion of the earth's natural capital stock, as reflected by the decline in the Living Planet Index.

31 Ecological Engineering
defined as "the design of the human society with its natural environment for the benefit of both" (Mitsch & Jorgensen, 1989). integrates various existing environmental fields such as classical ecology, agro-ecology, and restoration ecology. used to design low-impact systems for waste treatment, food and energy production, habitat restoration and other benefits. should provide useful services for human society while at the same time retaining their function as an ecosystem.

32 Constructed Wetlands for Wastewater Treatment
Source: The community of Houghton Lake, located in the central lower peninsula of Michigan, has a seasonally variable population, averaging approximately 5,000. A sewage treatment plant was built in the early 1970’s to protect the large shallow recreational lake. This treatment facility is operated by the Houghton Lake Sewer Authority (HLSA). Wastewater from this residential community is collected and transported to two 5-acre aerated lagoons, which provide six weeks detention. Sludge accumulates on the bottom of these lagoons, below the aeration pipes. Effluent is then stored in a 29-acre pond for summer disposal, resulting in depth variation from 1.5 feet (fall) to 10.0 feet (spring). Discharge can be to 85 acres of seepage beds, or to 85 acres of flood irrigation area, or to a 1500 acre peatland. The seepage beds were used until 1978, at which time the wetland system was started up. The wetland has been used since that time, with only occasional discharges to seepage or flood fields. The average annual discharge is approximately 120 million gallons. Secondary wastewater is intermittently discharged to the peatland during May through September, at the instantaneous rate of 2.6 mgd. Provisions for chlorination are available, but have not been used, because of low levels of fecal coliform indicator organisms. Water from the holding pond is passed by gravity or pumped to a 3-acre pond which would provide chlorine removal in the event of the necessity of its use. Wastewater from this pond is pumped through a 12-inch diameter underground force line to the edge of the Porter Ranch peatland. There the transfer line surfaces and runs along a raised platform for a distance of 2,500 feet to the discharge area in the wetland. The wastewater may be split between two halves of the discharge pipe which runs 1,600 feet in each direction. The water is distributed across the width of the peatland through small gated openings in the discharge pipe. Each of the 100 gates discharge approximately 16 gallons per minute, under typical conditions, and the water spreads slowly over the peatland. The branches are not used equally in all years. The peatland irrigation site originally supported two distinct vegetation types. One called the sedge-willow community included predominantly sedges (Carex spp.) and Willows (Salix spp.). The second community was leatherleaf-bog birch, consisting of mostly Chamaedaphne calyculata (L.) Moench and Betula pumila L., respectively. The leatherleaf-bog birch community also had sedge and willow vegetation, but only in small proportions. The edge of the peatland contained alder (Alnus spp.) and willow. Standing water was usually present in spring and fall, but the wetland had no surface water during dry summers. The leatherleaf-bog birch cover type generally had less standing water than the sedge-willow cover type. Soil in the sedge-willow community was 3-5 feet of highly decomposed sedge peat; while in the leatherleaf-bog there is 6-15 feet of medium decomposition sphagnum peat. The entire wetland rests on a clay “pan” several feet thick. The wetland provides additional treatment to the wastewater as it progresses eventually to the Muskegon River eight miles away. Small, natural water inflows occur intermittently on the north and east margins of the wetland. These flows are partially controlled by beaver. Interior flow in the wetland occurs by overland flow, proceeding from northeast down a 0.02% gradient to a stream outlet (Deadhorse Dam) and beaver dam seepage outflow (Beaver Creek), both located 2-3 miles from the discharge (Figure 1.) Wastewater adds to the surface sheet flow. Hydrogeological studies have shown that there is neither recharge or discharge of the shallow ground water under the wetland. The treated wastewater arriving at the peatland is a good effluent which contains virtually no heavy metals or refractory chemicals. This is due to the absence of agriculture and industry in the community. Phosphorus and nitrogen are present at 3-10 ppm, mostly as orthophosphate and ammonium. BOD is about 15 ppm, and solids are about 20 ppm. Typical levels of chloride are 100 ppm, pH 8, and conductivity 700 mmho/cm. The character of the water is dramatically altered in its passage through the wetland. After passage through ten percent of the wetland, water quality parameters are at background wetland levels. The system has operated successfully in the treatment of 1900 million gallons of secondary wastewater over the first sixteen years.

33 Additional Resources Ecology Endangered Species
Ecological Society of America Endangered Species US Fish and Wildlife Service

34 Ecological Engineering
Exotic Species Sea Grant Ecological Engineering International Ecological Engineering Society American Ecological Engineering Society

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