eco_services


 * Abstract **

Ecosystem services are goods and services provided by a functioning ecosystem that humans enlist for beneficial use. They are essential to the everyday functioning and long-term survival of humanity. They ensure both sustenance and quality of life. Ecosystem services are linked to biodiversity of natural ecosystems which is in turn a product of a natural ecosystems health. Both terrestrial and aquatic ecosystems, and therefore their ecosystem services are threatened by anthropogenic changes and modification. Understanding of the linkages between local and global processes is important for assessing and regulating quality of services provided both now and in the future. Economically, ecosystem services provide humanity services that are monetarily significant on a global scale annually. Replacing or restoring ecosystem services is difficult, and can be financially nonviable. Climate change also presents a global issue. Differential warming and timing of change in areas presents challenges to science to understand ecosystem services, and how humanity affects their status.


 * Ecosystem Services **


 * Introduction **

Ecosystem services are functions performed or carried out by healthy ecosystems around the world. It is important to note that an ecosystem is the combination of all biotic and abiotic elements of an area, and ecosystem Services are functions performed by the ecosystem itself that provide either direct or indirect benefits to humans. Different types of ecosystems provide varied ecosystem services benefits that depend on the characteristics and the health of the ecosystem. For example, terrestrial ecosystems provide a large portion of the food supply that humans consume every day. Aquatic environment encompass many important ecosystem services, despite freshwater only being 0.8% of the earth’s surface (Dudgeon et al. 2006). Some of the ecosystem services provided by a healthy, naturally functioning aquatic ecosystem include: supplying of freshwater, water purification, flow regulation, and natural disaster regulation (Gutierrez et al., 2013). Ecosystem services derive from a complex set of systems. Often there is a mixture of physical, chemical, and biotic components that are interacting to create the net benefits observed (Gutierrez et al., 2013). The extent to which an ecosystem’s benefits are being provided or which benefits are being derived from a specific part of an ecosystem is not always clear. Complex interactions between physical processes, chemical interaction, and biotic influence are difficult to identify. These linkages and interacting processes causes the environmental conditions that provide ecosystem services to be fragile. For example, Local disturbances or disturbances in an upstream region of a water system could have impacts on ecosystem service availability or quality affecting a wide area.

There is an important linkage between ecosystem services and biodiversity. Higher biodiversity is linked to a more resilient and stable provisioning of ecosystem services (Worm et al. 2006). There are some important ramifications to this concept. This further increases the fragility of the aspects that combine to create ecosystem services. An abrupt change to a physical, chemical, or biological aspect may have a cascading effect on the other processes causing destabilization of ecosystem health, and therefore ecosystem service capacity. Physical changes like bank alteration, or channelization could destabilize a system. Artificially elevated chemical levels from fertilizer runoff, for example, could also destabilize an ecosystem. Both of these changes could have an impact on the biological realm of an ecosystem. The resulting changes could have an impact on one or more species vital to the partitioning and regulation of ecosystem services derived from an area. The interactions between the different elements of an ecosystem are not always equally disturbed by the same events in all areas. This makes each ecosystem unique in both its capacity to buffer and absorb disturbances. Two ecosystems and their subsequent ecosystem services may be affected differently by identical events.

Ecosystem function, properties, and services provided are all a combination of climate factors, frequency and magnitude of disturbances over time, and biotic factors (Hooper et al. 2005). Humanity is making unprecedented changes to both biodiversity and making phenomena like species invasion and species-caused extinction more prevalent and widespread than at any point during Earth’s history (Hooper et al. 2005). A review of literature by Hooper et al. in 2005 found five potential problems linked to ecosystem services caused by loss of biodiversity: 1. A species function in their ecosystem has profound impacts on energy and material flows through a system, as well as important impacts on other species in an ecosystem through competition, mutualism, predation, etc. 2. The absence of a species from an ecosystem can cause disruptions in goods and services rendered from an ecosystem, and it can be both expensive and difficult if not impossible to restore the goods and services by artificial means. 3. Each ecosystem reacts differently to species losses, and the way those losses are exhibited can vary from place to place. 4. Specific species loss does not always cause degradation to ecosystem services. There may be another species that performs similar function, function may be unaltered initially after species loss, or abiotic processes may dominate for a specific function. 5. More rather than fewer species are needed to contribute to a constant supply of goods and services as conditions become variable over time. As variation over time and space is introduced into a system, higher biodiversity allows for a sort of buffering capacity for long-term change (Hooper et al. 2005).

However, biodiversity is not the only factor that plays into an ecosystem’s ability to provide and garnish services. There are many other factors that contribute as well. Many of the factors and processes that determine the services and their quality from an ecosystem are highly influenced and altered by humans as well. Global climate change means that anthropogenic effects are on every scale, from local to global (Hooper et al. 2005). Figure 1 shows a flowchart of all the different contributors and factors that go into the partitioning of ecosystem services exhibits the complex interactions and displays where and how changes to certain systems can cause cascading and important effects on other systems.



** Figure 1. ** A flowchart depicting the feedbacks and connections present on ecosystem-level scales. (From Hooper et al. 2005).

Areas of abiotic homogeneity can sometimes become places where conditions are ideal to have low biodiversity. The low biodiversity that occurs in these areas can be explained by the lack of niches, or homogeneity of available niches, leaving room for fewer species to uniquely inhabit and exploit the available resources. This low biodiversity coupled with areas of low variation in physical and chemical conditions can be caused by local disturbances, and these conditions could limit an ecosystem’s ability to properly function (Basset et al. 2013). These local disturbances to biodiversity and ecosystem functionality are unwanted, and important to understand. However, at the global scale there is a lack of understanding for how global losses in biodiversity affect, or will potentially affect large-scale ecosystem function (Worm et al. 2006). If humans want to continue to reap the benefits provided by ecosystems around the world, and they necessarily must, much knowledge is needed. A greater understanding of the relationships between the different aspects of an ecosystem, how they relate, and ultimately translate to provide a specific benefit must be better understood. Once these factors are more understood, efforts can be made to mitigate damage, or even reverse damage to aspects of ecosystems that are vital to providing services can be assessed and implemented.

To be addressed in this paper are some of the threats to ecosystems and their services in both the aquatic and terrestrial realms. A glance into the how ecosystem services factor into the global economy, and what changes could mean will be addressed as well. Finally, the effects of climate change and its effects to global ecosystem services will be assessed as well.


 * Discussion **


 * Freshwater Ecosystems **

Freshwater comprises only about 0.1% of the global water supply and only about 0.8% of the surface of the Earth is covered by freshwater (Dudgeon et al. 2006). This small portion of freshwater represents effectively all the water available for consumption by not only humans, but by all life. This small fraction of the surface of the earth provides a habitat for 100,000 species (Dudgeon et al. 2006). Many species evolved in a specific environment, adapting certain characteristics to survive in that habitat. Many systems in their natural, unaltered state find long-term equilibrium and remain stable for many years. In this stability, regulation of natural nutrient cycle and flow of energy through systems are included in this long-term steady state. Because of this, changes to a steady-state area can have repercussions to areas downstream in an aquatic environment. Disturbances can propagate through systems very quickly. For example, abrupt changes to local systems can have widespread and sometimes poorly understood consequences on a large scale.

Aquatic environments provide services in many forms. Some of the most important are: freshwater, flow management, soil creation, hydro-power, aesthetic benefits, climate dynamics, food, natural resources, and recreation (Gutierrez et al., 2013). Along with these services, water provides important pollution and pesticide removal aspects as well (Sweeney et al. 2004). All of these services both directly and indirectly benefit humans on a global scale. Changes to different aspects of different environments may have different effects on different scales. It is important to observe that not all ecosystem services come in the form of tangible assets that can be quantified. A service provided from a healthy water system can be clean water, or it could be a satisfying view, or spiritual value. Figure 2 from Brauman et al. 2007 shows some of the ecohydrologic processes and some of the hydrologic services rendered by the ecosystem itself. There is a direct link between ecosystem performance, direct effect to the ecosystem itself, and a benefit reaped by society. Quality of life impacts are an important consideration that could easily be overlooked when considering ecosystem services, however it is an important portion of a healthy ecosystem's contribution to humanity.

** Figure 2. ** A linkage between ecosystem processes and hydrologic services provided at an ecosystem level (From Brauman et al. 2007).

Human caused degradation is one of the largest threats to water bodies in the world (Millennium Ecosystem Assessment). Several categories listed for the root cause of the degradation of wetland areas world-wide are: infrastructure development, land conversion, water withdrawal, eutrophication and pollution, overharvesting, and overexploitation, and the introduction of invasive species (Millennium Ecosystem Assessment). It's important to note that one of the main sources and drivers for the difficulties facing not only ecosystem services and global stability in general is increasing human population. Stressors on the global ecosystem caused by increasing population are likely to continue to rise in tandem with increasing global population.

Coastal ecosystems, particularly areas of unique habitat, such as estuaries, and other ecotones are threatened globally (Basset et al. 2013). A large part of the threat comes from economic development along coasts (Basset 2013). 39% of the United States population lived in coastal shoreline counties, excluding Alaska, in 2010 according to stateofthecoast.noaa.gov. Coupled with increased human population comes increased potential for ecosystem degradation. For some of the coastal areas of the United States this may mean a decline in some intangible ecosystem services such as aesthetic qualities of an area or recreational value of coastline (Basset 2013). If areas are degraded to a severe enough level in coastal areas, loss of both ecosystem function and economic value could occur. Unique habitats like estuaries, where freshwater runs into salt water, are home and transportation routes to many unique and charismatic species. Much more study is needed to understand how these unique environments interact with ecosystems at a local and global level.

One of the most important aspects of freshwater ecosystem services is the freshwater itself (Gutierrez et al. 2013). Many humans around the world rely on local watersheds to provide access to drinking water. Important chemical purifications in freshwater be it the removal of pesticides or the reduction of a harmful chemical can occur in freshwater at little or no cost to humans. A degradation of an aspect of an ecosystem that provides access to water that has been “purified” by natural processes may cause a reduction or even cessation of access to that water. This may have several consequences. Either an area may have to be abandoned because of lack of access to freshwater. Freshwater may have to be imported from elsewhere to the area, likely at great cost. Or, physical processes that provide the same types of cleaning processes to the water may have to be implemented in the area, likely also at great monetary cost. This is an example of how loss of ecosystem services may impact an area economically. The Millennium Ecosystem Assessment found that anywhere between 1.5 and 3 billion people world-wide depend on groundwater for their source of daily drinking water (Millennium Ecosystem Assessment). Increased rates of pollution and contamination combined with reduced recharge to aquifers due to groundwater pumping for agricultural use is likely to be a complicating factor in the future for those who rely solely on groundwater for consumption purposes.

Loss or degradation of wetlands, including rivers and lakes, in poorer countries can have impacts on human health, including the control of disease vectors (Mill Ecosystem Assessment). Also, quality of life may decrease as population in these countries rises and ecosystem service capacity of a wetland may stay the same or decrease. For example. Capacity for storm water control, or denitrification may be inadequate in certain areas if service levels stay constant and demand levels rise (Millennium Ecosystem Assessment).

Biodiversity in aquatic systems is threatened currently (Dudgeon et al. 2006), which also means that ecosystem services in aquatic systems are threatened. The top five categories of threats to aquatic bio diversity are: Over-exploitation, water pollution, flow modification, habitat degradation, and species invasion (Dudgeon et al. 2006). The extent that each species interacts with and affects its environment is not completely understood and aquatic microbiology, and fugal ecology is poorly understood in aquatic environments (Dudgeon et al. 2006) The need for further study in these fields is important, particularly because of the influential role that microbes play in the biogeochemical cycle, and pollution and pesticide removal (Sweeney et al. 2004). With increasing inputs of chemicals into the aquatic environment and the potential effects to the water supply may demand a heavier dependency on the ecosystem to provide filtration. In addition, excess chemicals may adversely affect one group of organisms in an area, having a cascading effect which could affect both chemical and physical properties of a system of the long-term.

**Terrestrial ecosystems**

The terrestrial biome covers around 30% of the Earth, and is used extensively for human activities. The terrestrial biome is a continuing source of ecosystem services, benefits, and beneficial use to humans. Agriculture provides a significant portion of the food that allows for the existence of over 7 billion people on the planet. Along with the the photosynthesizing life in the oceans, the terrestrial biome is also responsible for manufacturing a large portion of the oxygen that humans and other life uses for respiration. In recent times, however there has been a massive shift towards intensive agriculture and intensive land use practices around the world (Foley et al. 2005, Tscharntke et al. 2005, Tilman et al. 2001). This shift towards intensive agriculture can have significant negative impacts on both ecosystem services and biodiversity directly (Foley et al. 2005, Tscharntke et al. 2005). Some of the local level effects of intensive agriculture are shortening crop rotation cycles, decreasing crop diversity, and cultivating monocultures of high yield crops (Tscharntke et al. 2005). Some landscape consequences of agricultural intensification are converting perennial habitat from grassland to arable field. Fragmenting natural habitat, monocultures, Simplifying landscapes through implimenting landscape homogeneity, and loss of biodiversity through decreased natural habitat and food sources ( Tscharntke et al. 2005).

Foley et al. 2005 published an extensive article detailing some of the consequences and questions surrounding land use changes and their possible long term effects on human societies. Some of their results are as follows: 35% of carbon dioxide emissions since mid eighteenth century have been a direct result of land use. Anthropogenic inputs of nutrients into the environment from sources such as fertilizer and air-born pollutants have surpassed natural sources, which greatly affects both land and water quality. Nearly 40% of the land surface of the earth is covered by crops or pasture land, while differential land use has allowed for grain harvests to double in the past [50] years. Also during the past [50] years, an almost 700% increase in global fertilizer use has occurred, which causes crop yields to be much higher, but has severe consequences as well (Foley et al. 2005). Figure 3 shows a diagram of the transitional forms of land use, from pre-settlement to intensive agriculture and gives a break down of what percentage of land surface is partitioned for what type of use. In the intensive agriculture stage, there is a large amount of modification that can be seen to natural ecosystems. This means that naturally functioning ecosystems are very rare, which means ecosystem services are at a far less than optimal state.



** Figure 3. ** A diagram depicting changing land types associated with land use development (From Foley et al. 2005) The results of this type of landscape change and modification can be seen also in figure 4. This figure shows the potential vegetation of areas on Earth by type, and then categorically shows the area that is used for crops, rangeland, and pastureland rather than the natural ecosystem that it has potential to be. Typical intensive farming involves the cultivating of monocultures ( Tscharntke et al. 2005). This practice lowers biodiversity in much the same way that a homogenous abiotic environment might. There are few niches available to exploit, so there is a decreased amount of competition among species, so only certain species are able to thrive in an area, and usually that number of species is low compared to a natural environment, so a decline in biodiversity is realized.



** Figure 4. ** A depiction of natural vegetation potential, and actualized range,crop, and pasture land (From Foley et al. 2005)

Along with modifications to the terrestrial environment, modifications to biogeochemical cycling and hydrologic cycling has also occurred on a local and global scale (Foley et al. 2005) There are few natural cycling processes on earth that have not been extensively altered in either their timing or scale by anthropogenic sources. Massive changes to the timing of where and when water is delivered has been made as well as water quality issues. Nutrient additions to water supplies have caused problems with eutrophication, or intense algal growth, in the Gulf of Mexico. Increased nitrogen inputs cause algae to grow in immense quantity and area in the gulf which causes problems of many varieties (ners.noaa.gov) These problems can cause drops in other ecosystem services such as food from oceanic sources. This shows that ecosystem services alteration is not solely a local phenomenon. There are global consequences to all actions which all must be taken into acount collectively.

**Economic Effects**

An economic assessment of ecosystem services and their potential economic importance was done in 1997 by Costanza et al. They found that ecosystem services provided globally, be it freshwater, or fresh air, had a value of between $16 and $54 trillion (Costanza et al. 1997). This provides insight into why ecosystem services are vital, not only from an environmental and resource standpoint, but from an economic standpoint as well. Having to pay even $16 trillion more per year for services previously provided by healthy, functioning ecosystems would be debilitating to the global economy. Not only that, but many of the functions provided by the ecosystem are either prohibitively expensive to perform on large scales, or technologically impossible right now. This puts added pressure on science to understand the links between all the different aspects of ecosystem service provisioning.

Given that world population is increasing and showing few signs of slowing down, it becomes important to understand how global processes can affect ecosystem services and how ecosystem services can be guaranteed to future generations. More than just economic value, humans rely on ecosystem services for quality of life. Humanity relies the environment for security, basics for a high quality life, health, and social interactions. Figure 6 shows a linkage and scaling of the importance of these factors and the connections they have directly to ecosystem services. Figure 5 gives context of all the different ecosystem services and benefits we receive from the environment. The scale of the figure also shows the potential for each different constituent of the environment, including humans, to affect one another

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 * Figure 5. ** Examples of ecosystems, and some of the services they provide (From Millennium Ecosystem Assessment).
 * Figure 6. ** How ecosystem services relate directly to societal benefits, and their importance. (From Millennium Ecosystem Assessment).

Along with assessing ecosystem service value, the task of monitoring and ensuring compliance with standards set for regulation and insurance of ecosystem services is also an important area of study, and execution. The United States enacted the Clean Water Act in 1972 in an effort to responsibly manage aquatic ecosystems and ensure that their value and functionality is maintained for future generations. The EPA has a set of monitoring standards that they use and implement to ensure that water is safe enough to swim in, consume fish from, or use to irrigate crop supply (Overview of Watershed Monitoring). This holds both people and entities accountable for the quality of local ecosystems, and helps to regulate future uses of ecosystems.

**Climate change**

Another stressor to almost every global ecosystem is climate change. From habitat alteration to flow regime changes to temperature regime changes, climate change will have an irreversible effect on all ecosystems, and therefore potentially ecosystem services. Systems will potentially become non-steady state, and organisms that evolved under a certain life history strategy, such as a specific temperature regime, could be adversely affected by rapid change. Models are being developed that help to predict the effects of climate change. These models may be able to assist in pointing out areas that may need more attention that others, or even strategies to mitigate as much damage to ecosystems as possible. Thinking in terms of ecosystems services is not the traditional approach to thinking about climate change. In reality, many issues facing communities to regions to countries to even continents when dealing with climate change are going to be largely ecosystem service factors. Clean water supply, food supply, materials to provide electricity. These are all important services that will no doubt be affected. The challenge will be to see the warning signs for certain areas before conditions become too difficult to overcome.

Figure 8 shows a depiction of temperature changes in change in annual mean air temperature and anuall temperature range. Xia et al 2014 suggests that temperature changes are not uniform with latitude and that changes are also differential when it comes to diurnal variation (Xia et al 2014). This has consequences for carbon sequestration and plant biomass accumulation in differing parts of the world. Also, importantly this emphasizes the fact that there are changing factors all the time when it comes to global ecosystem services. A stressed and differential climate over long term may have varying effects on amount and availability of water which could in turn have cascading effects of its own. The main idea with climate change is to expect the unexpected. There are models which predict incredible amounts of change and models that are more modest in their approach. Climate change is an important variable in the realm of ecosystem services and their future.

** Figure 7. ** Trends in annual mean air temperature in degrees C (top) and annual temperature range in degrees C (bottom) (Modified From Xia et al. 2014).


 * Conclusions **

Ecosystem services provide humanity with necessities needed for not only the sustenance of life, but also quality of life. Their importance in an everyday world cannot be overstated. However, the maintenance and quality assurance of the resources we use from the ecosystem is also of utmost importance. Extensive modification to the Earth's terrestrial and aquatic biomes has occurred at an unprecedented rate over the past decades. The main driver for this change is the increasing human population and its ever increasing demand for the use of these ecosystem services. The quality and effectiveness of ecosystems will need to be assessed and maintained in order for future generations to be able to reap the benefits of ecosystems. Many ecosystem services are provided without monetary cost by the environment itself. To replace or supplement these services can be extremely costly, and sometimes impossible. Also, replacing services once they are gone can be difficult on a short-term, and even long-term scale.

Ecosystem services are linked inexorably to biodiversity. The ability for an ecosystem to perform its intended service is very dependent on the species composition and a natural regime of the land. The significance and change associated with climate change provides an interesting challenge to many types of scientists. Trying to grasp already poorly understood linkages between physical, chemical, and biological processes in the context of an environment of flux is a difficult task, but it is what faces society and science in a modern world. Demand for the benefits of ecosystem services is going to increase, so the need for the ecosystem to be robust and resilient is greater than ever. This represents one of the greatest challenges to science and humanity to date.


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