openLandscapes - Regulating Ecosystem Services

Regulating Ecosystem Services

University of Kiel, Ecology Centre, MSc Environmental Science, a seminar paper
1st version completed 11/19/2009 by Hui Zhang and Rieke Scholz (longdancao@gmail.com and riekescholz@web.de)
2nd version (adapted, changes)2010 by Roshani Sitaula (rosni.sweetsmile@gmail.com)
Status: in working (2010)

Regulating Ecosystem Services

Abstract

“Regulating services are benefits people obtain from the regulation of ecosystem processes, including air quality maintenance, climate regulation, erosion control, regulation of human diseases, and water purification” (MA, 2005). Human activities have a negative impact on regulating services like climate regulation and natural hazard regulation, as well as on other services. This does not only influence ecosystems on a local scale but also on the global scale, since the ecosystems are closely interlinked. One way to demonstrate the importance of regulating services is to put an economic value on them. Attempts of valuation by Costanza et al. (2007) account for example 684 billion per year on global climate regulation. It is very difficult to put a price on individual regulating services, but any kind of attempt can be helpful for making right decisions in the process of ecosystem modifications.

Key words: regulating services, climate regulation, natural hazard regulation, economic valuation .

Content

1. Introduction

The different species on the planet interact with each other in many ways and the term ecosystem has been defined on the basis of interaction these species have among and between themselves. The ecosystems are the natural environment that provides human with goods and services via ecological processes and structures. Human benefits from the good and services rendered by the ecosystem. According to the Millennium Ecosystem Assessment (MA), ecosystem services are the benefits that humankind enjoys from the resources and processes provided by the natural ecosystem. Human health and well being depends totally on the services provided by the ecosystem and their different constituents like water, soil, nutrient etc. Based on different functions, the ecosystem services have been categorized into four groups by the MA that includes the provisioning, regulating, cultural and supporting services. The daily necessities required for the human well being for instance food, water, timber and fiber falls under the category of the provisioning services, regulating services are the one responsible for the habitable environment, a place where its possible to live for humans for instance, air and water quality, climate change, erosion control etc are some aspects that is maintained by this services. Cultural services are the non material services human are provided by the ecosystem and supporting services helps the ecosystem to prosper or enhance the growth of the system. These services are essential to maintain all other services and the go hand in hand with each other.The Millennium Assessment Report (MA), published in the year 2005, did a broad investigation on these ecosystem services, their importance for human well-being, their actual state, as well as direct and indirect drivers for their change. This paper gives an overview over the regulation services, describes some examples in detail, and discusses their condition, as well as their economic value.

Figure 1. The strength of linkages between categories of ecosystem services and components of human well-being.(Millennium Ecosystem Assessment)

Ecosystems are the most integral part for any organisms as everyone depends upon them for the fulfillment of their needs in a way or another. The needs or the goods for instance water and air quality maintenance, climate regulation, natural hazard regulations are some of the most important services delivered by the ecosystem. The Millennium Ecosystem Assessment (MA, 2005) has categorised these services as regulating services and is defined as: “Regulating services are benefits people obtain from the regulation of ecosystem processes, including air quality maintenance, climate regulation, erosion control, regulation of human diseases, and water purification” (MA, 2005). They maintain a world in which it is biophysically possible for people to live. Additionally to the main regulating services mentioned in the MA definition, there are many others, which can be separated into three different categories (Bauman and Daily 2008):

Cycling and filtration processes	Detoxification of waste Generation and renewal of soil fertility Purification of air and water
Translocation processes	Dispersal of seeds Pollination of crops and other plants
Stabilizing processes	Coastal and river channel stability Control of the majority of potential pest species Carbon sequestration Partial stabilization of climate Protection from disaster - Mitigation of flood and droughts - Moderation of weather extremes

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2. Climate Regulation

Ecosystem services play an important role in the mitigation of climate change. These services has been modified by human through various anthropogenic activities some of them being the change in land use and land system, deforestation that supplies the atmospheres with huge amount of additional carbon dioxide and greenhouse gases such as nitrous oxide and methane. Over the last two centuries approximately 40% of the historical emission and in the 90’s 20% of the current carbon dioxide emissions is the outcome of the deforestations and change in land use and it is anticipated that the change will continue throughout the twenty first century. Agricultural practices is responsible for the emission of around 30% of the other greenhouse gases methane and 90% of nitrous oxide emissions (driven by the use of fertilizers) and natural processes in wetland ecosystem that account about 25-30% of methane emission. The changes in climate have pronounced effect on biological diversity as a result of which the capability of ecosystem to deliver their services has also been degraded. The climate has been influenced both locally and globally by the ecosystems.

2.1. Global Scale

Ecosystems have an influence on global climate by emitting greenhouse gases or aerosols to the atmosphere or by absorbing greenhouse gases or aerosols from the atmosphere. In another words, warming (as a source of green house gases) and cooling (as a sink for green house gases) are two processes in which the global climate is being affected by the ecosystems. The greenhouse gases in the atmosphere evolved together with life in ecosystems. It keeps the earth warm and makes the earth habitable for human beings.
Ecosystems stabilize the climate through carbon cycling. All living organisms contain carbon. Soil, natural gas, peat and coal are mainly made of carbon. Rainforests and oceans absorb more carbon dioxide than they emit. They absorb about half the carbon dioxide humans release into the atmosphere. They are known as carbon sinks (Natural Environmental Research Council 2009).
Due to human activities, such as fossil fuel burning and clearance of forests, the composition of the atmosphere changed recently. More greenhouse gases in the atmosphere increased the temperature of the earth surface and caused climate change.
The following chart shows the changes in atmospheric composition, alteration in land surface reflectance (albedo), and variation in the output of the sun for the year 2000 relative to conditions in 1750.

Figure 2. Contribution of Ecosystems to Historical Radiative Forcing and Current Greenhouse Gas Emissions (MA 2005)

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2.2. Regional and Local Scale

Ecosystems have influence on local or regional temperature, precipitation and other climate factors. The forest enhances local humidity through transpiration (the process by which plants release water through their leaves), and thus amplifies local rainfall. For example, 50 to 80 percent of the moisture in the central and western Amazon remains in the ecosystem water cycle. In the water cycle, moisture is transpired and evaporated into the atmosphere, forming rain clouds before being precipitated as rain back onto the forest. The recycling of rainfall is quicker and the amount of precipitation increases when vegetation is present leading to denser vegetation canopy. The reduction of rainfall in an area is a consequence of reduced water cycling due to land degradation. When the forests are cut down, less moisture is evapotranspired into the atmosphere resulting in the formation of fewer rain clouds. Subsequently there is a decline in rainfall, subjecting the area to drought (Butler 2006). The climate has been affected in regional and local scale by the change in land cover in positive as well as negative way however the negative impacts are more profound. The tropical deforestation and desertification serve as a good example of reduce local rainfall.

We also notice that after the clearance of forests, the ecosystem failed to offer the regulating service of climate, it had an impact on other services of watershed and provisioning services as well. Climate changes together with human activities become the driving force of changes of different ecosystem services. It shows the importance of regulating service among the four types of ecosystem services. Here is the example of the impact of climate changes on ecosystem service in general.

Table 1. Three examples of current and projected climatic changes, their effects on ecosystems, and potential consequences to the supply and delivery of watershed services. Climatic changes are based on current trends and projections from the Intergovernmental Panel on Climate Change Fourth Assessment Report (2007). For all changes, uncertainty is substantial and the geographic variability is expected to be high. ↑=probable increase, ↓=probable decrease,▲=change (US Forest Service 2008).

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3. Natural Hazard Regulation

With the increasing population of the modern world, the demands for daily necessities have also increased. Demand for food, shelter, fiber compelled the population to find a solution for existence. Especially in the developing countries due to poverty, regions and localities exposed to extreme events have been increasingly occupied by the human for example coast, floodplains and areas close to fuel wood plantation. Fire and floods are among those natural hazards that are recurring and result in huge loss of both lives and property. Both human as well as a natural system is impaired due to the frequent occurrence of these extremes. These are the two events most directly influenced by human activities such as urbanization and environmental degradation and has influenced the planet for centuries. The advancement of human society exacerbates these events and the trend is seen to be increasing in general.

Natural hazards, as floods and fires, are “natural processes or phenomena occurring in the biosphere that may become damaging for human as well as for natural systems” (MA 2005). The outcome can become a natural disaster depending on the severity of its damage on the human system. But it is important that natural hazards do not have only negative effects, they can also bring benefits to the natural system. Floods, for example, allow groundwater aquifers to recharge, regular burning is necessary for some seedling to germinate. According to the MA the impact of these natural disasters has changed dramatically over the last 30 years and these changes also affect other ecosystem services. Such natural hazards are regulated or the recurrence of these events are to some extent influenced by the ecosystem and their services and which in turn effect the human well being.

Figure 3. Inter-relationships between Extreme Events, Ecosystems, and Social Systems (Regulation of Natural Hazards: Floods and Fires, Manoel Cardoso, Johan Goldammer, George Hurtt, Luis Jose Mata).

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3.1. Flood Regulation

Natural systems are well adapted to regular floodings. Wetlands and Floodplains are able to reduce the impact of floods in many ways. First of all, wetlands act like a sponge, they store water and release it slowly, which reduces the flood peaks and thus reduces the need of expensive flood protection engineering (Finlayson and Moser 1991). Natural soils have a high water holding capacity due to their large pore size. Another important aspect is the vegetation, which helps to stabilize the banks and shores and maintains a shallow water depth. The accumulation of sediments counteracts forces of erosion, subsidence and sea level rise (Finlayson and Moser 1991).
Furthermore wetlands as well as mangrove forests and coral reefs reduce the damaging effects of tropical cyclones by absorbing storm energy. They decrease the area of open water for wind to form waves, reduce direct wind effects on the water surface and are able to directly absorb wave energy due to the shallow depth (Simpson and Riehl 1981). Natural mashes sustain only little damages of the storms and thus they act as buffer zone protecting coastal communities, which are vulnerable to damage (Gosselink and Mitch 2007).
Direct Drivers of this change are mainly climate change and sea level rise, which is a great threat especially to coastal wetlands. A sea level rise of one meter would threaten half of the wetlands designated by the Ramsar Convention on Wetlands and could reduce the coastal wetland area in the USA by about 26 to 66 % (Gosselink and Mitch 2007). The wetlands are not able to adapt to the sea level rise, because they are trapped between the rising sea and the dikes or bulkheads, which protect the dry upland from inundation. Thus there is no vertical accretion of marsh sediments possible and this increases inundation, erosion and salt water intrusion. This phenomenon is called coastal squeeze and has already occurred in many countries, e. g. in the Netherlands (Gosselink and Mitch 2007).
Other direct drivers are the changes in land use and in hydrological systems, such as the straightening of rivers (MA 2005). But there are also indirect drivers such as population increase in vulnerable areas and urbanisation. The areas exposed to extremes events like coast and flood plains or areas near to the fuel plantation are being hugely occupied by humans. Especially in the developing countries it is at present a big problem. In Bangladesh about two third of the country was flooded in 1988 flood. In the United States approximately 70% of all urban land is located in the 100 year flood plains. In Japan, for example, about 50% of the population and 70% of the infrastructure is located on floodplains, which account for only 10% of the land area (Gosselink and Mitch 2007).

Floods are the most frequent natural calamities and the number has been increasing significantly on all continents. Loss of natural buffers like wetlands, forests, mangroves has reduced the capacity of the ecosystem to regulate the extreme events.

All these drivers are partly responsible for the drastic increase of flood events in the last decades. But these data should be interpreted with caution. One reason for the increase can also be an increase in measuring and recording flood events in the last decades.

Figure 4. Number of Recorded Flood Events by Continent and Decade in Twentieth Century (MA 2005)

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3.2. Fire Regulation

Fire regulation is the “capacity of ecosystems to maintain natural fire frequency and intensity” (MA 2005). Fire activity depends on climate and land cover. Hot conditions and intense winds may promote high fire activity, intensify fuel dryness, and fire spread (MA 2005). Natural systems are adapted to burning and in some cases they even depend on it. Natural fires help to sustain and rejuvenate ecosystems through periodic burning. They are important for landscape structure, biodiversity, and species composition. Natural structures stop fires from spreading and the biological decomposition processes reduce the potential fuel for wildfires (MA 2005). Fire incidents have contributed also to the degradation of air quality.

Figure 5. Number of Recorded Wild Fires by Continent and Decade in Twenties Century (MA 2005)

But similar to flood events, fire events are also increasing (as shown in Fig. 5) due to similar reasons (MA 2005). A very important tool to measure fire events and monitor the changes is remote sensing.

Fires and floods are the natural phenomena which play a crucial role in cycling of matters and energy. Fires are part of natural behavior and floods are effective means of natural transport of dissolved or suspended material. (Pielke Jr. 2000b).

Direct drivers are climate change and the change in land cover and land use (agricultural techniques). Another aspect is fire suppression. If natural fires are suppressed artificially, the system increases fuel loading and thus increases fire intensity in the future. An indirect driver is the population increase in fire risk areas and also the increase of fire raising.
It is also increasingly accepted that a large pool of species is required to sustain ecosystem structure and functioning and that biodiversity may act as a buffer for environmental changes (MA 2005). So biodiversity loss might also be a driver, since it is especially important after a disturbance for the ecosystem to regenerate.

Table 2. Key Role of Ecosystems in Regulating Extreme Events (Regulation of Natural Hazards: Floods and Fires, Manoel Cardoso, Johan Goldammer, George Hurtt, Luis Jose Mata)

Ecosystem	Role in Flood Regulation	Role in Fire Regulation
Cultivated	crop cover provides flood protection, conditioned on good management	part of the management of some cropping systems, e.g., sugar cane, timber, etc.
Dryland	protection through vegetation cover; recharge of aquifers	biodiversity issues: adaptation mechanisms to fire
Forest	protection from floods providing flood attenuation and soil loss prevention	part of the natural system; reducing wood fuel accumulation; biodiversity issues
Urban	move people away from flood-prone areas, conditioned on good urban planning	move people away from natural fire-prone areas; scale benefits from more effective fire prevention and control
Inland	Waters provide mechanisms for flood attenuation potential (wetlands, lakes, etc.)	wildfires control, e.g., pit fires control by wetlands
Coastal	benefits from sediment transport to the coastal zone; flood protection provided by coastal ecosystems (barrier beaches, mangroves, etc.)	not applicable
Marine	benefits from nutrient transport to the oceans	not applicable
Polar	discharge regulation to oceans in the Arctic system (freshwater provision to Arctic oceans)	not applicable
Mountains	regulating flood-related events (slope stability)	main source of wood fuel
Islands	benefits from sediment transport to oceans through floods from the mainland; aquifer recharge as main source of fresh water	not applicable

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4. Water regulation, purification and waste treatment

Water regulation, purification and waste treatment are another important services ecosystems provide. The ecosystems are capable of regulating the magnitude and timing of flooding and runoffs. The change in ecosystem alters the timing of runoff, change the water storage potential of the system, and influence the aquifer recharge.
The water quality is declining globally; this is mainly due to the grown concentration of nitrate in past few decades. Ecosystems act as an effective medium that filter out and decomposes the organic waste dumped untreated into the water bodies and regulates the water quality. They absorb the waste and detoxify the compounds via several soil and subsoil processes. The capacity of the natural ecosystem to purify the waste is limited as the water bodies have been heavily polluted. With the increase in the population, the waste and contaminants are also increasing and as a result of this some ecosystems have been severely damaged for instance wetlands are decreasing in the modern world due to the expansion of agricultural land. Loss of these wetland ecosystems has decreased the ability of ecosystem of filtering out and decomposing the wastes. Water quality has been severely degraded in cultivated, urban and dry land systems.
The ability of any ecosystem to detoxify the waste differs from one ecosystem to another. The millennium ecosystem assessment has reported that 90-95% of all sewage and 70% of industrial waste are dumped into the surface water without treatment in the developing countries. An average of 80% of nitrogen that has been loaded globally can be cleaned by the ecosystem but the ability of these ecosystems varies.

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5. Condition and Characteristics of Regulating Services

5.1. Condition of Regulating Services

Ecosystem and the services are sophisticated and not well understood and the replacement for these services or to reproduce these services with the most advanced technology is not possible. These services operate in every aspects of our livelihood and due to various several reasons these services provided by ecosystem are in decline.
“The condition of the service depends more on whether the ecosystem’s capability to regulate a particular service had been enhanced or diminished and the level of production is not relevant” (MA 2003).
When a lake lost its self-cleaning ability due to sewage discharge into the lake, the water purification service, which the lake can offer, is degraded. When humans cleared the forests, they did not know that they degraded the ecosystem’s capability to regulate a service such as cooling the temperature. Only few studies about the condition of regulating service have been carried out after human modification of ecosystem. But the condition of regulating services is vital for human welfare both now and for generations to come.

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4.2. Global Status of Regulating Services

The table below summarizes the MA’s finding on ecosystem services. The “Status” column indicates whether in the recent past the condition of the service globally has been enhanced (▲) or degraded (▼) or whether there has been no consistent global pattern (▲+▼).

Table 3. Global Status of Regulating Services

Service	Subcategory	Status	Notes
Air quality regulation		▼	Declining ability of atmosphere to cleanse itself
Climate regulation	global	▲	Net source of carbon sequestration since mid-century
	regional and local	▼	Preponderance of negative impacts
Water regulation		▲+▼	Varies depending on ecosystem change and location
Erosion regulation		▼	Increased soil degradation
Water purification and waste treatment		▼	Declining water quality
Disease regulation		▲+▼	Varies depending on ecosystem change
Pest regulation		▼	Natural control degraded through pesticide use
Pollination		▼	Apparent global decline in abundance of pollinators
Natural hazard regulation		▼	Loss of natural buffers (wetlands, mangroves)
(MA 2005)

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5.3. Dynamics and Stability in Regulating Services

The ecosystem responds to perturbations in a dynamic way. It has the ability to stabilize in spite of the changes within a certain level which is called buffer capacity. For instance the soil has a buffer capacity against acid inputs. However the buffer capacity has limitation. When the amount of changes or disturbances go beyond the threshold, the ecosystem is not able to keep the original regime and it changes into another regime which offers less ecosystem services and has less self-organization capability. It is hard to determine when the regime shift starts since the ecosystem capacity and threshold is not fully understood.

Levin (1999) suggested that natural systems are complex adaptive systems that will probably change and turn into new systems in the face of environmental stresses. This means the maintenance of the services on which humans depend is fragile. “There is no reason to expect systems to be robust in protecting those services—recall that they permit our survival but do not exist by virtue of permitting it, and so we need to ask how fragile nature's services are, not just how fragile nature is” (Levin 1990).

Figure 6. Dynamics and Stability in Ecosystem Services (MA 2005)

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5. Economic Value of Regulating Services

Human are benefitting from the goods and services provide by the ecosystem in their everyday life. The importance of these services has been understood from the scientific view point for quiet a time now but the quantification of these processes has started recently. The blooming population, development and different several activities pose severe impact and eventually lead to the impairment of these services. Most of the ecosystem services are for free and they are undervalued or overlooked in both private and public sectors. These services are not traded in the market and this lack of market or market price that evaluates the services is always a problem for the planner and decision makers. The monetary value of the ecosystem services and goods are most of the time estimated by the economist although the economic value is not necessarily based on money. But the argument has been put forth by some people that ecosystem services have right to exist independently (Goulder and Kennedy 1997). On the other hand counter argument is that the services will be exploited and lost if proper monetary values are not placed. (Costanza et.at 1997a). It is not an easy job to determine or allocate the economic value to all kind of ecosystem services. There are different ways which attempt to measure the economic value of ecosystem services. First of all you can take the market value of a special service into account. This is easy to apply on provisioning services but more difficult for regulating services. Another way it to calculate the cost of damages caused by the loss of an ecosystem service, or the expenditure to prevent that damage, or to calculate the cost of replacing the ecosystem service altogether. What would it cost to replicate a service in a technological produced, artificial biosphere (Costanza et al. 1997)?
The third way would be to take the willingness to pay by the people into account. But this is also difficult to apply. Because the benefits gained by regulating services are often essential. This way is easier applicable for cultural services.
The valuation of ecosystems is a widely discussed topic. Some argue that it is impossible or unwise to put a value on such 'intangibles' as human life or environmental aesthetics (Costanza et al. 1997). But nevertheless there are some examples given in the following table.

Table 4. Economic Value of Regulating Services (Costanza et al. 1997)

Service	Total global value (Billion $ per year)
Gas regulation	1341
Climate regulation	684
Disturbance regulation	1,779
Water regulation	1,115
Pollination	117
Water treatment	2,277

Tab. 4 shows the economic value of some exemplary regulating services, calculated by Costanza et al. (1997), using a combination of the methods mentioned above. In the following chapter a more detailed example is discussed.

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The Value of Coastal Wetlands for Hurricane Protection in the USA

Since the 1700s, more than half of all the wetlands in the USA have been lost. Today they make up 4 % of the bay watersheds which is an area of about 27 million acres. The coastal population on the other hand has increased steadily since 1970, and currently more than half the population of the United States lives in coastal states. This development is one reason for the diminishing wetlands. Due to governmental regulations the rate of coastal wetland loss has declined in the last decades (NOAA 2008).
Costanza et al. (2008) calculated the monetary value of the coastal wetlands in the USA. The calculations are based on 34 hurricanes that have hit the USA between 1980 and 2004. The data of the hurricanes and their wind speed was combined with spatially data on gross domestic product (GDP) and the herbaceous coastal wetland area (marshes). The data of the hurricane damage included both direct (e. g. damage to infrastructure) and indirect (e. g. unemployment or market destabilisation) consequences on the local economy. The results show a decrease of relative damage with increasing herbaceous wetland area. Wind speed increases the damage costs as well as GDP since there is more infrastructure to be damaged. The calculated annual values of wetlands per hectare range between USD 256 (Delaware) and USD 51,110 (New York) depending on the state and its vulnerability. The mean annual value is a little over USD 8,000 per hectare.

The results sum up to a total annual value of USD 23.2 billion which the coastal wetlands in the USA provide with respect to hurricane protection. These values emphasize the importance of the preservation and restoration of coastal wetlands even though this is a very cost-effective strategy for society. But the coastal wetlands as “horizontal levees” provide numerous other ecosystem services which vertical, artificial levees do not (Costanza et al. 2008). The values for the damage costs will even increase in the future, when the frequency and intensity of hurricanes increase due to climate change (Costanza et al. 2008). The number of intense storms in the Atlantic since 1995 was more than twice the level of the 1970 to 1994 period and 2005 was the most active year ever for Atlantic hurricanes on a range of measures (IPCC 2007). And not only the frequency of hurricanes might increase in the future, but also the intensity and destructiveness might increase with rising global mean temperature (Emanuel 2005).

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6. Conclusions

The increasing human population imposed severe threat to the ecosystem and their services to meet their daily basic necessities. The resources and services provided by the ecosystem have often been taken as granted. The misconception that these resources are free of charge and are unlimited has encouraged human to exploit the ecosystem. So is the case for regulating services too. However any change or disturbance which has been carried out by human society accumulated in the ecosystems. Some even caused the collapse of the ecosystem. Those changes have not only influence on the local area but also have impact on the global scale since the ecosystems are closely interlinked. Especially the change in climate regulation has a negative effect on other services in global scale.

So far there is no simple technical substitution for regulating services. It is possible to build a water treatment plant which substitutes the water purification service but it is not possible to substitute the whole watershed regulating functions. Even when it is possible to substitute the service, the people who benefit from the substitution are not the ones who suffer from the loss of natural ecosystem services. This causes another social problem.
Last but not the least, it is difficult to put a price on individual regulating service, but any kind of attempt to evaluate regulating service is helpful for making right decisions in the process of ecosystem modifications.

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References

Bauman, K. A.; Daily, G. C. 2008: Ecosystem Services, Human Ecology, pp 1148-1154.
Bledzki, L. A. 2008: Ecosystems and Human Well-being Synthesis: Appendix A. Ecosystem Service Reports, http://www.eoearth.org/article/Ecosystems_and_Human_Well-being_ Synthesis~_ Appendix_A._Ecosystem_Service_Reports [10.05.2009].
Butler, R. A. 2006: Local and National Consequences - Loss of Local Climate Regulation. http://rainforests.mongabay.com/0902.htm [10.05.2009].
Costanza, R, Cumberland, J, Daly, H, Goodland, R and R Norgaard. 1997a. An Introduction to Ecological Economics. St Lucie Press, Boca Raton, Florida
Costanza, R; Pe´rez-Maqueo,O.; Martinez, M., L.; Sutton. P.; Anderson, S., J.; Mulder, K. 2008: The value of coastal wetlands for hurricane protection. Ambio 37(4), pp 241-248.
Costanza, R., d`Arge, R., de Groot, R., Farber, S., Grasso, M., Hannon, B., Limburg, K., Naeem, S., O`Neill, R.V., Paruello, J., Raskin, R.G., Sutton, P., van der Belt, M., 1997: The value of the world's ecosystem services and natural capital. Nature, 387, 253-260.
Daily, G C, Alexander S, Ehrlich, P R, Goulder, L, lubchenco,J, Matson, P A, Mooney, H A, Postel, S, Schneider, S H, Tilman, D and G M Woodwell. 1997. ecosystem services: bebefits supplied to Human Societies by Natural Ecosystems. Issues in Ecology 2:I-16
Emanuel, K. 2005: Increasing destructiveness of tropical cyclones over the past 30 years. Nature 436, pp 686–688.
Finlayson, M.; Moser, M. 1991: Wetlands. Toucan books, London, pp 8-26. Gosselink, J. G.; Mitch, W. J. 2007: Wetlands. John Wiley and Sons, Inc., New Jersey, 4th edition, pp 327-.349.
IPCC (Intergovernmental Panel on Climate Change) 2007: Assessment of observed changes and responses in natural and managed systems. Climate Change 2007: Impacts, Adaptation and Vulnerability, p. 110. http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter1.pdf [27.07.2009].
Levin, S. A. 1990 in Rechkemmer, A.; von Falkenhayn, L. 2009: The Human Dimensions of Global Environmental Change: Ecosystem Services, Resilience, and Governance. EDP Sciences.
Manoel Cardoso, Johan Goldammer, George Hurtt, Luis Jose Mata: Regulation of Natural Hazards: Floods and Fires,
Millennium Ecosystem Assessment 2005: Regulation of Natural Hazards: Floods and Fires, http://www.millenniumassessment.org/documents/document.285.aspx.pdf [27.07.2009].
Millennium Ecosystem Assessment 2003: Ecosystems and Human Well-being, Island Press.
Natural Environmental Research Council 2009: What are carbon sources and carbon sinks? http://www.nerc.ac.uk/research/issues/climatechange/carbon.asp [27.07.2009].
National Oceanic and Atmospheric Administration (NOAA) 2008: Coastal Wetlands, http://chesapeakebay.noaa.gov/wetlands"> [31.03.2011].
OECD 2008: Strategic Environmental Assessment and Ecosystem Services. www.oecd.org/dataoecd/24/54/41882953.pdf [10.05.2009].
Pielke Jr., R.A., 2000b: Floods impacts on society. In: Floods, Vol.I. D.J. Paker (ed.), Routledge, London
US Forest Service 2008: Climate Change and Water - Perspectives from the Forest Service. http://www.fs.fed.us/ccrc/files/CC%20and%20Water%20In%20Brief.pdf [31.03.2011].

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