Interdisciplinary Project
University of Amsterdam
21/05/2016
Developing a framework for land use on a changing
low arctic tundra in Alaska:
A comparative analysis between boreal forest and agricultural land
Borgman, C., Nieuwkerk, M. & Penning, J.
Earth Sciences, Biology & Economics
10556583, 10484574 & 10424679
Tutor: Myrte Mijnders
Expert: Kenneth Rijsdijk
8667 Words
2
Table of contents
Introduction ... 3 Conceptual framework ... 6 Research methods ... 7 Results ... 9 Biodiversity ... 9 Carbon sequestration ... 14 Food production ... 17Raw material production ... 20
Water quality regulation ... 20
Conclusion ... 22
Discussion ... 22
References ... 24
Appendix A - Glossary ... 28
Avoided Cost (AC) ... 28
Biodiversity ... 28
Biome shift ... 29
Carbon cycle ... 31
Direct market valuation ... 32
Ecosystem services ... 32
Invasive species ... 33
Replacement Cost (RC) ... 33
Soil hydrology ... 33
Soil pH, nutrient cycling and nutrient availability ... 34
Pedogenesis... 35
Vegetation functionality ... 35
Appendix B - Calculations ... 37
Food production Agricultural land – Direct Market Valuation ... 37
3
Abstract
Low arctic tundra is disappearing due to climate change. Model projections show that as much as 40% of tundra can be replaced by boreal forest by the year 2100. Besides, on former tundra agriculture will be possible. This research explores the implications of land use change towards boreal forest or agriculture. A comparative analysis is made on five ecosystem services, which were selected based on importance in the region, after which economic valuation methods are applied upon these services.
The analysis shows that the monetary values of biodiversity, carbon sequestration and water quality regulation are higher in boreal forests. Raw material production and food production monetary values are higher on agricultural land. However, it is concluded that the most appropriate land use does not solely depend on the economic value, but also on the location and specific stakeholder. The methods and results can therefore be used as a framework for further research by various stakeholders.
Introduction
Due to climate change, the tundra is disappearing. Along the Arctic to sub-Arctic boundary, the tree line has moved about 10 km northwards, and 2% of Alaskan tundra on the Seward Peninsula has been displaced by forest in the past 50 years (Lloyd et al., 2003; as cited in Anisimov et al., 2007). Model projections, as used by Walker et al. (2005), show that increasing temperatures could result in the loss of as much as 40% of the current tundra as it is replaced by boreal forest through a biome shift (Appendix A) by the year 2100.
Tundras are vast treeless landscapes beyond the climatic limit of forests that are characterized by low shrub vegetation (Arctic Climate Impact Assessment, 2004; Bliss, Heal & Moore, 1981). The Northern Hemisphere accommodates most of the tundra areas, although some tundra areas can be found in South America and Antarctica. On the Northern Hemisphere, tundras appear in Alaska, Canada, Greenland, Norway, Sweden, Finland and Russia.
In this report a distinction is made between high arctic tundra and low arctic tundra based on the vegetation and animal composition (Bliss, Heal & Moore, 1981). In general, the low arctic tundra is located closer to the equator and has a shallow thaw layer while high arctic tundra has a deep thaw layer. Since this research is focused on the tundra, which is most susceptible to a climate change induced biome shift, the used research area is the low arctic tundra. Moreover, this research is focussed on Alaska, because the tundra biome of Alaska consist of only low arctic tundra (Bliss, Heal & Moore, 1981). The Alaskan low arctic tundra consist of sub shrub heath, cotton grass sub shrub and wet sedge grass tundra (Bliss, Heal & Moore, 1981). In this research, low arctic tundra encompasses all these forms of tundra vegetation. Figure 1 shows the occurrence of the tundra biome in Alaska.
The low arctic tundra provides several ecosystem services, of which one of the most important is carbon sequestration. The world’s tundra areas have a potential stock of about 500 Pg of labile carbon in yedoma permafrost, 400 Pg of carbon in permafrost and 144 Pg of carbon in the soil (Zimov, Schuur & Chapin, 2006; Sabine et al., 2004). Frozen yedoma from Alaska contains about 10 to 30 times the amount of carbon usually found in deep, non-permafrost mineral soils (Zimov, Schuur & Chapin, 2006). This ecosystem service is currently under an immense pressure due to climate change. Between approximately 1985 to 1990 the tundra
4
has turned from a global carbon sink into a carbon source (Oechel et al., 1993). This is caused indirectly by the raising temperature, through enhanced drainage, soil aeration and a decrease in the water table (Oechel et al., 1993). Furthermore, the tundra areas acting as a carbon source could be a strong positive feedback loop for global warming (Oechel et al., 1993; Fischlin et al., 2007).
Another important ecosystem service of the tundra is biodiversity, which consists of endemic biodiversity as well as tundra-dependent migratory species, contributes significantly to the global biodiversity (Fischlin et al.,
2007). With increasing temperatures, there will be a decline in abundance non-vascular plants and an increase of woody plants in the tundra areas. Moreover, the overall biodiversity will decrease (Walker et al. 2005). Furthermore, the decline in diversity will probably occur most in forbs and in mosses. Since the tundra maintains its soil thermal regime especially through the mosses in the area (Chapin et al., 1995) this will once again act as a positive feedback loop for global warming.
Furthermore, some of the tundra areas are the home of several indigenous people. In Alaska these are the Aleut, Alutiiq, Inupiat, Central Yup'ik and Siberian Yupik (State of Alaska, 2016). It can be seen that in the tundra area of Alaska (figure 1), the population is mostly indigenous (figure 2), who are more dependent on local food. Furthermore, they consist mostly of the Central Yup’ik and Inupiaq tribe (figure 3). This presents a unique body of cultural knowledge traditionally transmitted from generation to generation (Fischlin et al., 2007).
Figure 2. Total and indigenous populations of Alaska. Reprinted from ‘Total and indigenous populations of the Arctic: Alaska’ by Rekacewicz, 2005.
Figure 1. Tundra biome in Alaska. Reprinted from ‘Where is the Alaska’s tundra’ by State of Alaska, 2016.
5
The tundra areas are changing, and this process can neither be retained nor undone. However, there are alternative land uses that provide the same and other ecosystem services. In this paper, a comparative analysis between boreal forest and agricultural land is made. We chose for boreal forest, since this will become the natural situation without further human intervention, and agricultural land, because a lot of indigenous people are dependent on a local food supply (Bliss, Heal & Moore, 1981). To determine what the most beneficial land use is, the perspectives of earth sciences, biology and economics are combined and integrated to create a framework.
Therefore, the main research question is: What are the implications of land use change towards boreal forest or agricultural land in a changing low arctic tundra in Alaska? This question will be answered by answering five sub questions:
1. What ecosystem services do boreal forest and agricultural land in Alaska provide? 2. What are the most important ecosystem services of boreal forest and agricultural land? 3. What is the extent of these ecosystem services?
4. What valuation techniques should be used to assess these ecosystem services? 5. What are the values of these ecosystem services?
The overview of this interdisciplinary research is as follows. Firstly, the conceptual framework is presented. Then the research methods are explained. Subsequently, the results and conclusion are given. Lastly, our discussion, references and appendices are provided.
Figure 3. The indigenous people of Alaska per tribe. Reprinted from: ‘Indigenous peoples and languages of Alaska’ by Krauss, Holton, Kerr, & West, 2011.
6
Conceptual framework
During this research, several core concepts and theories are discussed. For the earth scientist, these were climate change, nutrient cycling, carbon sequestration, soil organic matter and water quality. The biologist encountered the concepts of biodiversity, ecosystem services, vegetation functionality and biome shifts. The economist uses the theory of ecosystem service valuation, with the concepts of direct market valuation, replacement cost and avoided cost. All these concepts and theories are explained in detail in appendix A.
The main component of the comparison between boreal forest and agricultural land in this paper are the ecosystem services. Ecosystems provide goods and services that are important for the functioning of the biosphere and provide benefits for human society (Millennium Ecosystem Assessment, 2005). These ecosystem services are mainly divided into four categories: supporting, provisioning, regulating and cultural services (De Groot, Alkemade, Braat, Hein, & Willemen, 2010; MEA, 2005). Supporting services are necessary for the production of all other ecosystem services, for example primary production and biodiversity. Provisioning services are products obtained from ecosystems such as food, fibre, medicine and cosmetics. Regulating services are the benefits obtained from the regulation of ecosystem processes. They include climate, water, disease and pest regulation, protection from natural hazards and water and air purification. Cultural services are the services that satisfy human spirituality and their appreciation of ecosystems and their components (Fischlin et al., 2007). When the services provided by an ecosystem are positive for human society, these are called ecosystem services, but when they have a negative influence, they are called disservices. Since boreal forest and agricultural land are different ecosystems, with different species, it is to be expected that the ecosystem services will also differ.
Boreal forests provide several ecosystem services, of which the production of timber products and carbon sequestration are the most prominent (Fischlin et al., 2007). Furthermore, boreal forest provides the ecosystem services of climate regulation (Meher-Homji, 1992; as cited in Myers, 1997; Fischlin et al., 2007), landscape stabilization (Woodwell, 1993; as cited in Myers, 1997), soil protection and nutrient cycling (Ehrlich and Ehrlich, 1992 as cited in Myers, 1997; Fischlin et al., 2007), pest and disease control (Woodwell, 1995; as cited in Myers, 1997), water preservation and regulation (Bruijnzeel, 1990; as cited in Myers, 1997; Fischlin et al., 2007), flood and drought protection (Sfeir-Younis, 1986; as cited in Myers, 1997) and the provisioning of habitat, biodiversity, numerous non-timber products and recreation (Fischlin et al., 2007).
On the other hand, agricultural land provides several ecosystem services, of which food, fibre and fuel production are the most prominent (Zhang et al., 2007; Swinton et al., 2007; Power, 2010). The other ecosystem services agricultural land provides are carbon sequestration and regulation of soil fertility (Zhang et al., 2007; Swinton et al., 2007 & Power, 2010); water supply, nutrient cycling, pest control, genetic diversity of agricultural species and soil retention (Zhang et al., 2007 & Power, 2010); biodiversity conservation (Swinton et al., 2007 & Power, 2010); aesthetics and recreation (Swinton et al., 2007) and the provisioning of wildlife habitat and crop pollination (Zhang et al., 2007).
Furthermore, agriculture provides several ecosystem disservices. For example, it remains one of the key sources of water pollution (Holden, 2013; Swinton et al., 2007; Power, 2010). Other ecosystem disservices agriculture provides, are health risks caused by pesticides and excess nutrients (Zhang et al., 2007; Swinton et al., 2007 & Power, 2010); the loss of biodiversity
7
(Swinton et al., 2007 & Power, 2010); habitat loss ( Zhang et al., 2007); the sedimentation of waterways and the emission of greenhouse gasses (Power, 2010) and the emission of unpleasant odours according to (Swinton et al., 2007).
As stated before, the economist made use of the concept of ecosystem service valuation. However, the valuation of ecosystems has been criticised. Nunes & van den Bergh (2001) describe that economic valuation of ecosystems and biodiversity provide a very incomplete perspective on values. According to them, the problem mainly lies within the passive or non-use value of biodiversity. However, it is possible to correctly assess monetary values of ecosystems and biodiversity, but this requires intensive studying and a complete understanding of the situation (Nunes & Van den Bergh, 2001). This would require a full study, and was out of the scope of this research. However, the delivered results of this report could lay the foundation for further studies.
Research methods
This section describes the methods used to achieve results and to create common ground between the disciplines. Each discipline has studied multiple sources and condensed them into a literature report. Through interdisciplinary use of knowledge, useful results have been attained to answer the research questions.
A successful implementation of this method requires finding common ground between disciplines. When the common ground is clear, the conflicts between disciplines can be overcome, which enables the collective collection and analysis of results. The way common ground was achieved for this report can be seen in figure 4 and 5. Biology and earth science share a lot of common theories and concepts in ecology. Thus the knowledge was unified under ecology. Combining the knowledge allowed for discussion of several phenomena relevant to the case. Further integration is needed to also create common ground between ecology and economy. This is not as straightforward, because the paradigms of ecology and economy clash. Both disciplines have a different perspective on the world.
Since the objective of the economist is to valuate the different proposed land uses, an interdisciplinary definition of value has to be sought after. From an economic perspective, value is determined through an interaction between demand and supply for a good or service, while the ecological idea of value revolves around the contribution to science and the intrinsic value of nature.
8
This conflict has been overcome by using the integrative techniques of extension and organisation. Firstly, extension was applied to come up with a definition of value beyond its disciplinary implication and thereby creating a common ground. The concept of ecosystem services, used in both ecology as well as in environmental economics, was used to accomplish this. Secondly, the different ecosystem services were organized in different function categories, as defined by the Millennium Ecosystem Assessment (2005). Thus, the links between the value of a specific land use according to the different disciplines became clear. After common ground was established, the biologist and earth scientist looked at the ecosystem services that forest and agricultural land provide. Subsequently, a set of indicators for ecosystem service potential was determined by choosing the ecosystem services deemed most important for this case. Furthermore, the presence of the selected ecosystem services per hectare was researched. Thereafter, the economist looked at theories and frameworks of appraising and valuing all the aspects of ecosystem services. Lastly, these theories were applied to calculate the value of the ecosystem services in US dollars per hectare.
From the described ecosystem services in the conceptual framework, the five that were deemed most important are biodiversity, carbon sequestration, food production, raw material production and water quality regulation. Biodiversity was chosen because it is the foundation of many other ecosystem services both locally and globally (Fischlin et al., 2007). Secondly, carbon sequestration was chosen because this service is one of the main factors that will be altered by a changing climate and the subsequent biome shift. Furthermore, it is an important factor for future climate change, therefore it is of global importance. Thirdly, food production was chosen because many indigenous people are dependent on country foods (Fazzino & Loring, 2009) and food security is a growing issue in Alaska (Loring & Gerlach, 2015). Additionally, raw material production was chosen because a large part of the economic value of both agricultural land and boreal forest comes from this local ecosystem service (Anielski & Wilson, 2009; NASS, 2016). Lastly, water quality regulation was selected because good water quality is one of the main requirements for life. Moreover, it is relevant for this research since agriculture is one of the main causes of water pollution (Holden, 2013).
These five ecosystem services have been further analysed in the results and are used to compare boreal forests with agricultural land. The valuation of these ecosystem services requires the use of several economic valuation techniques. In this research, direct market
9
valuation, the avoided cost method and the replacement cost method are used. These valuation techniques are elaborated on in appendix A.
The recommended land use will be based upon potential values of nearby boreal forest and agricultural use. Considering the scale at which the ecosystem services are effective, the best land use will therefore differ, depending on a global or local perspective.
Results
Here, the results of the five selected ecosystem services is presented. Each service is analysed and a comparison, between boreal forest and agricultural land in regards to the amount and value of the services, is made.
Biodiversity
Biodiversity is one of the key ecosystem services, because it is the foundation upon which many, if not all, of the other ecosystems services lay. However, the exact value of biodiversity itself is impossible to predict, since the ecosystem service of biodiversity expresses itself in many ways. In order to indicate a value, the concept of vegetation functionality (Appendix A) is used. Different categories, of functions a species can fulfil, are chosen and the presence and use of these functions in the different species are analysed. Each function can then be assigned a value. The value of one species will then be the sum of the values of the functions it fulfils. The total value of the biodiversity of an ecosystem will be the values of all the different species together.
Alaska has 1835 species, of which 26 are endemic. Of the 1835 species, 1354 are vascular plant species, 96 are mammalian species, 269 are bird species, 6 are amphibian species, 44 are freshwater species and there are no reptile species (Stein, 2002).
However, this is the biodiversity of entire Alaska. The biodiversity of the Alaskan boreal forest will be lower, since it is only a part of Alaska as well as only one ecosystem. The exact biodiversity of the new Alaskan boreal forest is difficult to predict, but it will resemble the biodiversity of the forest in inland Alaska, according to the theory of biome shifts (Appendix A). In order to get an exact number of species (per hectare) present in the Alaskan boreal forest, more local research will have to be done.
In order to give an indication of the biodiversity of the Alaskan boreal forest, the five most common tree genuses (spruce, alder, populus, birch and willow) as well as the great grey owl have been further analysed.
10
Great gray owl
The great gray owl (Strix nebulosa) is a permanent resident of the coniferous forests of central Alaska and it is protected under Alaskan federal and state law. The great gray owl is the tallest owl of Alaska, with a height of 48 centimetres and a wingspan of 1.37 meters. The owl is recognizable because of his gray colour with a white collar around his neck, his yellow eyes and the absence of horns. The great gray owl lives on the edge between grasslands and willow, spruce or poplar forests (Osborne, 1994). The distribution of the great gray owl is shown in figure 7.
This owl is considered beneficial, because it feeds on crops eating rodents and because it is one of the most sought-after bird species for bird watchers (Alaska Department of Fish and Game, 2015). Furthermore, it probably maintains the forest, since birds play a fundamental ecological role in the forest. This means that the species exert disproportionate influence on ecosystem structure or composition (Mills et al., 1993, and Paine, 1995; as cited in Alaska Department of Fish and Game, 2015). There is increasing data that supports the importance of birds in maintaining healthy forested ecosystems (Alaska Department of Fish and Game, 2015).
Figure 7. Reprinted from ‘Range map’ by NatureServe, 2015.
Figure 6. Great gray owl. Reprinted from ‘Alaska wildlife action plan’ by Alaska Department of Fish and Game, 2015.
11
Spruce
The spruce (Picea) is abundant in Alaska, from the interior of Alaska to Canada, and from the tree line in the north till the southernmost of Alaska. The species of spruce present in Alaska are the white, black and Sitka spruce (P. glauca, P. mariana and
P. sitchensis respectively). They can grow up
to twenty meters long and half a meter thick. Their needles are sharp and stiff and their cones hang down (Viereck & Little, 1972). Conifers are the economically most important trees in Alaska. The spruce trees are commonly used for building cabins, bridges and other constructions. They are also used often for fuel (Viereck & Little, 1972).
Alder
Alders are easily recognizable with their smooth gray bark with horizontal lines and their dark conelike elliptic fruit. They can become twelve meters high and with a diameter of 0.4 meter. The Alnus species present in Alaska are the American green, Sitka, red and thinleaf alder (A.
crispa, A. sinuata, A. rubra and A. tenuifolia).
The alders are found throughout Alaska, except for the upper north (Viereck & Little, 1972).
Alders are called nursing trees, because they improve soil conditions by adding organic matter and nitrogen. For example, the roots from alder trees have root nodules that fix nitrogen from the air and then enrich the soil. Furthermore, the twigs, buds and seeds are eaten by many songbirds. The wood produces good fuel and Alaskans use it to smoke fish. Sometimes the wood is used for hardwood furniture (Viereck & Little, 1972). Figure 8. Spruce. Reprinted from ‘Common trees of Alaska’ by Forest service, 2009.
Figure 9. Alder. Reprinted from ‘Common trees of Alaska’ by Forest Service, 2009.
12
Populus
The Populus genus has no English common name, so in this paper the scientific name for this genus will be used. In Alaska the Populus species are the balsam poplar, black cottonwood and the quaking aspen (P. balsamifera, P. trichocarpa and
P. tremuloides). They can grow up to 30 metres
high and one meter thick. They have broad leaves, down hanging flower clusters and small seeds. The Populus species are commonly found throughout Alaska (Viereck & Little, 1972).
The trees are mostly used for boxes and pulpwood. In the south of Alaska they are also planted to create shade. Furthermore, few of the trees are used for lumber (Viereck & Little, 1972).
Birch
The birch (Betula) has five species in Alaska, of which three species are trees. The three tree species are Western paper, Alaska paper and Kenai birch (B. papyrifera commutata, P.
papyrifera humilis and B. papyrifera kenaica). Birches have ovate leaves, conelike fruit and
their bark ranges from red-brown to white. The trees can grow up to 24 meters in height and 0.6 meters in width. They are widely distributed in the north-western part of Alaska (Viereck & Little, 1972).
Locally, birches are used as fuel for fireplaces or for mine props. Small amounts of birch are used for lumber or the making of furniture. Furthermore, birch is very suitable for making pulp and paper. In the past, Northern Indians used the bark for making canoes. Nowadays, the bark is viewed as pleasant and birches are planted as ornamentals (Viereck & Little, 1972).
Figure 10. Populus. Reprinted from ‘Common trees of Alaska’ by Forest Service, 2009.
Figure 11. Birch. Reprinted from ‘Common trees of Alaska’ by Forest Service, 2009.
13
Willow
In Alaska, the willow (Salix) is the genus with the most species, namely 33 species, of which eight species attain the size of a small tree. These eight species are the feltleaf, Sitka, grayleaf, littletree, Scouler, Bebb, Pacific and Hooker willow (S. alaxensis, S.
sitchensis, S. glauca, S. arbusculoides, S. scouleriana, S. bebbiana, S. lasiandra, and S. hookeriana). The willow is recognizable
for its slender twigs and the bitter taste of its bark. The leaves are usually long and narrow. The trees grow up to nine meters and 0.3 meter thick, with a few exceptions that can become eighteen meters high and half a meters thick. Willows can be commonly found throughout Alaska (Viereck & Little, 1972).
Willows have multiple uses, but the most common use is as a food source for moose. While some willow species are used as fuel, most of the willows are eaten by moose. Furthermore, willows are used to make furniture, since their wood shows a popular diamond pattern. The indigenous people of Alaska also use the willows for making baskets and for healing wounds (Viereck & Little, 1972).
In summary, table 1 displays the presence and use of the vegetation functionality of the above mentioned tree genuses. By analysing this table, it can be seen that with multiple species, more functionalities are being fulfilled. Thus, the more different species present, the more functionalities that are being fulfilled and the higher the monetary value of biodiversity becomes. Because of the scope of this research, the different functionalities were not given monetary values.
Functionality: Spruce Alder Populus Birch Willow Great Gray Owl Timber ++ +/0 + +/0 + - Fuel + + 0/- + +/0 - Food for animals 0/- + 0/- 0/- + 0/- Habitat provision 0 0 + 0 0 0/- Soil/nutrient regulation 0/- + 0/- 0/- 0/- - Ornamental 0/- 0/- 0/- + 0/- +
Table 1. Trees and their associated functionality. + indicates the presence and use of the function, 0 means neutral or unknown and - means that the function is not present or used.
Figure 12. Willow. Reprinted from ‘Common trees of Alaska’ by Forest Service, 2009.
14
Opposite to boreal forests, the biodiversity of agriculture can be seen as the amount of different crops planted, as well as the amount of species that live in or around the cropland. These species could be weeds growing at the edges of the field, beetles living in the ground and numerous insects living and/or eating of the crops. The exact amount of species is very difficult to predict, but on average it will be relatively low (Richards, 2001). The amount of vegetation functions that agriculture will fulfil will therefore be lower than those of boreal forest.
The exact value of the different vegetation function remains unknown, but it is evident that boreal forest will fulfil more functions. Therefore, the economic value of biodiversity will be significantly higher in boreal forests than on agricultural land.
Carbon sequestration
The second indicator used to compare boreal forest to agricultural land is the ecosystem service of carbon sequestration. Boreal forest sequestrates carbon both in biomass and in the soil. According to the fourth IPCC report (Sabine et al., 2004), the total amount of this carbon sequestration equals 150 Pg carbon in the soil and 57 Pg carbon in the biomass of boreal forests of the world (figure 13). Divided by the total surface area of boreal forests in the world this equates to 109.5 tonnes carbon per hectare in the soil and 41.6 tonne carbon per hectare in the biomass.
According to Nilsson and Schopfhauser (1995) the carbon storage of soils in boreal primary forests is between the 120 and 200 tonnes carbon per hectare (figure 14). Because the amount
Ecological Value
Boreal forest ++
Agricultural land 0/+
Table 2. Values of biodiversity for boreal forest and agricultural land. + indicates the presence and use of the function, 0 means neutral or unknown l and - means that the function is not present or used.
Figure 13. Surface area and carbon stocks divided over the world's biomes. F(b) stands for boreal forest, T for tundra and C for cropland. The brown bars represent the carbon stocks in the soil, green represents the plant biomass and blue the permafrost. Reprinted from ‘Ecosystems, their properties, goods, and services’ by Fischlin et al., 2007.
15
of carbon storage as used by the IPCC is substantially lower that the upper range of carbon storage as used by Nilsson and Schopfhauser (1995), the lower part of this range will be used to calculate the value of soil carbon sequestration of Alaskan boreal forest. Furthermore, the analysis done on the current soil from the Alaskan tundra (Appendix A; ‘Carbon cycle’) concurs that the carbon sequestration of the new boreal forest in Alaska will be in the lower range of Nilsson and Schopfhauser (1995). This is caused by the vulnerability of boreal forest soils, similar to that of tundra soils, to warming (Betts, 2000). Large parts of soil carbon storage can be lost, and even a net flux of carbon to the atmosphere can occur (Lindroth, Grelle & Morén, 1998).
The value of carbon sequestration used for valuation is 41.6 tonne carbon per hectare for the biomass and 120 to 140 tonne carbon per hectare for the soil, making a total of between the 161.6 and 181.6 tonne carbon per hectare of carbon sequestration in Alaskan boreal forests. On agricultural land, carbon sequestration only occurs in the soil since the carbon stored in the crops will become part of the carbon cycle after consumption. According to the fourth IPCC report, the total amount of carbon sequestration in croplands equals 252 Pg carbon (Sabine et al., 2004; as cited in Fischlin et al., 2007). Divided by the total surface area of cropland in the world this equates to 205.76 tonnes carbon per hectare in the soil. However, in this calculation, all the croplands in the world
are considered the same in their carbon sequestration ability. This is unlikely, since the carbon storage capabilities of soils differ greatly over different regions (figure 13). According to Nilsson and Schopfhauser (1995), the carbon sequestration of boreal agricultural land in between 96 and 165 tonnes of carbon per hectare in the soil (figure 14). This amount is noticeably smaller, which is to be expected considering the colder climates of boreal areas. From the analysis done on the current soil from the Alaskan tundra (Appendix A; ‘Carbon cycle’ & ‘Pedogenesis’) , it is expected that the carbon sequestration of the new agricultural land in Alaska will likely be near the lowest estimates of Nilsson and Schopfhauser (1995). This is mainly due to colder tundra soils having experienced less development and soil activity, which limits new organic matter deposition into the ground on new agricultural land. However,
over time with good cropping rotation the storage can increase (Reeves, 1997). In addition, organic matter will become more readily decomposable with warming (Bliss, Heal & Moore, 1981). Thus, only well-established agricultural land should meet the average or higher of the estimate by Nilsson and Schopfhauser (1995), whereas new agricultural land should be on the lower spectrum of the estimate.
Figure 14. Carbon content in soils for different areas and land uses. Reprinted from ‘The carbon sequestration potential of a global afforestation program’ by Nilsson and Schopfhauser, 1995.
16
The avoided cost method (Appendix A) is applied to determine the value of this ecosystem service. Social cost of carbon is therefore the indicator of choice to calculate the value of carbon sequestration. There is, however, no consensus within the grey and peer-reviewed literature regarding the significance of this indicator (Tol, 2008). Moreover, even within the peer-reviewed literature there are many variables that affect the eventual outcome (Ackerman & Stanton, 2012). The use of different models is an evident example.
The effect of using different models can be seen in the study by the Interagency Working Group (2010) on the social cost of carbon. They used three different models to estimate the social cost of carbon in 2010. A 3 percent yearly discount rate and an average climate sensitivity were used as parameters. The models that they used were the Climate Framework for Uncertainty, Negotiation, and Distribution (FUND), Policy Analysis of the Greenhouse Effect (PAGE) and a modified version of the Dynamic Integrated model of Climate and the Economy (DICE). The average outcome of these models were taken, which resulted in an estimated social cost of carbon of $21/tCO2, thus $77/tC. The PAGE calculated a social cost of carbon of $22/tC, while the costs found by FUND and the modified version of the DICE were significantly higher. FUND found a cost of $110/tC and the modified version of the DICE calculated the social cost of carbon to be $102.7/tC.
Next to the use of different models, Ackerman & Stanton (2012) have identified four major uncertainties that affect the social cost of carbon calculations within a singular model: the value of the climate sensitivity parameter; the level of climate damages expected at low temperatures; the level of damages at high temperatures; and the discount rate. Using the discount rate as example, the impact of changing one of these variables can be shown. The discount rate, which is the yearly percentage that future costs should be discounted to determine the present value, has a big impact on the social cost of carbon, because climate change affects life on earth over a long time horizon. Therefore, the discount rate is one of the most argued part of the social cost of carbon calculations. Nordhaus (2007) used the DICE with a yearly discount rate of 1.5 percent to find the social cost of carbon to be $35/tC in 2015. However, when using a discount rate of 0.1 percent, he found the social cost of carbon to be $360/tC in 2015. Moreover Ackerman & Stanton (2012) found, using the same modified version of the DICE as the Interagency Working Group (2010), that when a yearly discount rate of 1.5 percent instead of 3.0 percent is used, the social cost of carbon moves up from $102.7/tC to $432.7/tC in 2010.
Thus, the discount rate has a large impact on the height of the social cost of carbon. Changing other uncertainties, has similar effects and these effects amplify each other when multiple are simultaneously changed (Ackerman & Stanton, 2012). Besides, compelling arguments can be made for changing any of these uncertainties, yielding higher outcomes. Ackerman & Stanton (2012) calculated a range of $102.7 - $3271 per ton of carbon. The social cost of carbon of $102.7/tC, calculated by the modified DICE, can therefore be seen as a conservative estimate.
The enormous differences between and within both grey and peer-reviewed literature hinder picking a uniform cost to determine the value of carbon sequestration per hectare. However, to keep the value of this ecosystem service moderate to some degree, the more extreme values are disregarded. Therefore, the social cost of carbon of $102.7/tC, as calculated by the modified version of the DICE, is used.
17
Since the amount of carbon sequestration per hectare is given as a range, the total value will also be given as a range. For agricultural land the range is 96 - 165 tons of carbon per hectare, while the range of boreal forest is 161.1 - 181.6 tons of carbon per hectare. Therefore, the value of this ecosystem service on agricultural land is $9859 - $16946 per hectare; in boreal forest, the value is $16545 - $18650 per hectare. These findings are displayed in table 3.
Carbon in soil (tonne/hectare) Carbon in biomass (tonne/hectare) Total carbon (tonne/hectare) Value ($/hectare) Boreal forest 120-140 41.6 161.1 - 181.6 16545 - 18650 Agricultural land 96-165 - 96-165 9859 - 16945
Table 3. Amount and value of carbon storage for boreal forest and agricultural land.
Food production
Food production is an increasingly important ecosystem service in Alaska. Currently, Alaska produces the least amount of agricultural products of all states within the United States (NASS, 2016). Therefore, of all food consumed in Alaska, an estimate of 90 to 95 percent has to be imported (Fazzino & Loring, 2009). The consequence of importing such a huge part of all food consumed is that a lot of money is annually leaving the state. The AFPC (2012) states that a 2007 report of the United States Department of Agriculture (USDA) showed that Alaskans spent $1.5 billion on retail food expenditures. This implies that every year, $1.35 to $1.425 billion is not retained within the local economy.
However, many of the Alaskan Natives still rely on their own food production as well as on food gathered in the wild (Anisimov et al., 2007; Fischlin et al., 2007 & Loring & Gerlach, 2009), also known as country food. The per capita consumption of country foods is 465 g/day for rural Alaskans and 60 g/day for urban Alaskans, which together is valued on an estimate of 200 million US dollars per year (Anisimov et al., 2007). For Alaskan indigenous communities, country food can include several sea mammals, like whales, walrus and seals; ungulates, such as moose, reindeer and caribou; several fish species; waterfowl, berries, root crops and other plants (ACIA, 2004; Fazzino & Loring, 2009). However, the indigenous people living on the part of the low arctic tundra that is first to be affected by the biome shift, are located distant from the sea, and will therefore not have a marine animal diet. Their diet is focused more on freshwater fish, waterfowl and several fruit and vegetables. Next to being a food source, country foods are also linked to various cultural aspects of the indigenous lifestyle, through their role in preserving and transmitting traditions and cultural values (Loring & Gerlach, 2009).
For several reasons, the absence of a marine animal diet ensures that the effects of climate change will be less severe. Firstly, they do not hunt animals living on or in close proximity of the ice. Those hunting practices are under a lot of pressure due to climate change induced melting of sea ice (ACIA, 2004). Secondly, climate change induced vegetation shifts occur over long periods of time, enabling a smooth adoption to the new conditions. The transformation of tundra to boreal forest takes years and the boreal forest only moves up small
18
distances every year (Lloyd et al., 2003; as cited in Anisimov et al., 2007). Finally, some animal species, available on the tundra, will stay available once there is a boreal forest. For example, there will be a supply of freshwater fish independently whether there is tundra or boreal forest. Although the indigenous communities will not be heavily impacted by the biome shift of tundra to boreal forest, food production is still an important ecosystem service because of an increasing focus on food security and sovereignty all over Alaska (Loring & Gerlach, 2015). The Alaska Food Policy Council (AFPC) even identifies self-reliance as one of the core objectives for the coming years (AFPC, 2012). The large dependency on the import of food from outside Alaska decreases food security for two reasons. Firstly, the food prices in Alaska are, due to high transport costs, much higher than in most other states (Fazzino & Loring, 2009). Secondly, in case of a disaster there will only be food on the shelves for a couple of days, while there are no local possibilities to accommodate the supply of sufficient food (Fazzino & Loring, 2009). An increase in land use that provides food would therefore help to increase food security.
There are huge differences between boreal forest and agricultural land when it comes to food production. While food production is the main reason to choose for agriculture, it is solely a Figure 15. Produce availability per month of the year. Reprinted from ‘Alaska grown source book 2014-2015’ by Alaska Department of Natural Resources, Division of Agriculture, 2014.
19
by-product of boreal forest. Hence, the value attributed to food production can have a large impact on the choice for either agricultural land or boreal forest.
In boreal forests there are usually a few edible plants and some game that humans can use a food source. If there is a river or a lake in the forest area, freshwater fish can also be added to this, of which there are 44 species present in Alaska (Stein, 2002). In the Alaskan boreal forest a few of the edible plants are buffaloberry, bearberry and cranberry (Alaska Department of Fish and Game, 2015). The Alaskan boreal forest is also the home to bears, martens and other animals (Alaska Department of Fish and Game, 2015).
Agriculture provides food through the production of crops. Figure 15 shows the 27 crops produced in Alaska. Some crops do not fare well in Alaska, such as celery, leeks and pumpkins. These are only available as produce for a short amount of time. The value of food production on agricultural land can be calculated using direct market valuation and/or the replacement cost method, depending on the use of the products coming from the land. When the products are sold, direct market valuation should be used, while the replacement cost method should be used if the products are personally consumed. The value of food provisioning in boreal forest can be calculated using the same valuation methods.
The product chosen for calculation of the food provisioning value of agricultural land is the potato. Potatoes are the most commonly available vegetable in Alaska, the yield has been documented and the market value is available (NASS, 2016). The value of food provisioning on agricultural land when calculated with direct market valuation is $13282 per hectare (Appendix B).
However, to calculate the value of agricultural land that is used to produce food for personal consumption the replacement cost method should be used. This can be quite difficult since many different factors have to be accounted for, for example: the amount of hectares needed to provision enough food for one person, the costs of labour, the diet of the indigenous communities and the costs of purchasing food. Determining those values requires a study by itself and therefore some assumptions have to be made in order to calculate the value of agricultural land with the replacement cost method.
The first assumption is that the same amount of land is needed to feed the indigenous people of Alaska as is needed for others in Northern America on a yearly basis. Therefore, 0.72 hectares of cultivated land is needed to feed an indigenous person for a year (Fisher et al., 2010). Secondly, the costs of working the land are disregarded and are therefore presumed to be zero. Furthermore, it is assumed that the whole diet of the indigenous people can be produced on this agricultural land, removing the need to visit the supermarket. Lastly, the cost of purchasing food in the supermarket for the indigenous communities is supposed to be equal to the average food expenditure in Alaska. The yearly food expenditure of a family of four is used to calculate the average yearly cost per person, resulting in a yearly cost of $2321 per person. Using these assumptions, the value of agricultural land is $3224 per hectare (Appendix B).
In boreal forest the value of food production is determined by the value of edible products, for example mushrooms, berries and wild rice. Anielski & Wilson (2009) calculated, using direct market valuation, that the value of those products in the Canadian boreal forest is at least $79 million, but could be as much as $1.33 billion. Since the Canadian boreal forest covers a total of 242 million hectares, the value of those products is $0.33 - $5.50 per hectare. This value is
20
assumed to be similar to that of the Alaskan boreal forest, because the species composition and climate are very similar since the forests are an extension of each other. Moreover, Anielski and Wilson (2009) predict that the value of these products will increase in the coming years, as the economic value of these products is getting more and more recognized. Table 4 shows these findings.
Raw material production
The ecosystem service of raw material production can be present on both agricultural land as well as in boreal forest. Boreal forest provides raw material mostly in the form of timber, whereas the raw material provided by agricultural land is completely dependent on the type of agriculture. In the Alaskan boreal forest the five most common tree genuses are the spruce (Picea), alder (Alnus), willow (Salix), birch (Betula) and Populus. All these trees are suitable for timber (Viereck & Little, 1972). Furthermore, the populus and the aspen are used to make paper (Viereck & Little, 1972).
The value of raw material production on agricultural land and in boreal forests can be calculated using direct market valuation. In this research, the market value of the Canadian boreal forest is used as an estimation for the possible value of the boreal forest in Alaska. The Canadian boreal forest covers a total of 242 million hectares and the timber products had an estimated market value of $18.8 billion in 2002. Therefore, the estimated market value of the timber products in Canadian boreal forest is $78.02 per hectare (Anielski & Wilson, 2009). This value is assumed to be similar to that of the Alaskan boreal forest, because the species composition and climate are very similar since the forests are an extension of each other. Agricultural land will namely provide raw material when crops that are meant for fibre instead of food production, like cotton, are planted. In Alaska, a commonly found crop that provides raw material is hay (NASS, 2016). The State Agriculture Overview of Alaska (NASS, 2016) shows that in 2015, 18 million kilograms of hay has been produced on 7284 hectares in Alaska. The total value of the hay was $7.4 million and therefore the raw material value of that agricultural land was $1016 per hectare. The results are displayed in table 5.
Yearly value ($/hectare)
Boreal forest 78.02
Agricultural land 1016
Table 5. Value of raw material production for boreal forest and agricultural land
Water quality regulation
Water is a necessity for most life on earth. It is therefore important that water is of sufficient quality for uptake by plants animals and humans. This section will explore the positive and negative effects of boreal forests and agricultural land on water quality.
Yearly value ($/hectare)
Boreal forest 0.33 - 5.50
Agricultural land 13282 or 3224
21
‘Evidence suggests that more established vegetation, particularly the presence of trees, will lead to greater pollution reduction.’ (Holden, 2013). Moreover, when soil pollution is present, the pollution can be taken up by plants and trees, which is called phytoremediation (Salt, Smith and Raskin, 1998). The natural ability of plants and trees to concentrate compounds and metabolize them reduces pollution, and therefore can lead to an increase in water quality (Ibidem). Phytoremediation can be used for a wide variety of contaminants. The practice helps remediate heavy metal pollution, organic compound pollution and even nutrient pollution (Schnoor et al., 1995 & Salt et al. 1995 & McIntyre, 2003). It is a cost effective and environmentally friendly, since vegetation is used to solve the problem (McIntyre, 2003). The process is slow, because it is dependent on the growth of vegetation. The effects of phytoremediation depend on the type of pollution and location (Salt, Smith and Raskin, 1998). Not all types of vegetation are suited for phytoremediation (Ibidem).
Boreal forests, as studied in this report, have established vegetation and a lot of trees, thus will experience pollution reduction. In addition, the vegetation is quite varied compared to agricultural land. Therefore, phytoremediation occurs in forests, maintaining the water quality. Furthermore, on locations where pollutants are present, a forest will have a bigger positive influence on water quality. Thus, under these conditions, a steady or improved water quality is expected in a forest.
On the other hand, agricultural land has a relatively low biodiversity and presence of trees and thus might not have a high water quality regulation. Furthermore, since fertilizers are being used in agriculture, there is a high chance that it will actually contribute negatively to the water quality through nitrogen and/or phosphorous leakage (Van der Perk, 2013). This is diffuse pollution, which does not originate from a single point and can spread over long distances (Van der Perk, 2013). This could result in eutrophication in small streams or lakes (Vollenweider, 1968). In addition, while performing agriculture, the soil may lay bare for a large part of the year (figure 15). Since most crops are grown only in a few months, there is barely any use for land in the remaining months. Bare soil experiences more runoff and erosion than when vegetation is present, further negatively impacting water quality (Lenat, 1984). This is extra problematic because soil formation is slow in Alaska due to the low temperatures (Bliss, Heal & Moore, 1981). The negative impacts of pollution by agriculture will be experienced most near urbanized areas, because the drinking water supplies of these areas can be contaminated.
Since it is extremely difficult to determine the extent of this ecosystem service and thus to valuate it economically, the comparison of boreal forest and agricultural land will remain generic. It is, however, possible to see a general trend in regards to water quality regulation. This ecosystem service is generally positively or at least neutrally influenced by boreal forests and negatively by agricultural land. Table 6 sums up the outcomes.
Ecological Value
Boreal forest +/0
Agricultural land -
Table 6. Value of water quality regulation for boreal forest and agricultural land. + indicates the presence and use of the function, 0 means neutral or unknown and - means that the function is not present or used.
22
Conclusion
This study set out to determine what the differences between the two most probable land uses on changing low arctic tundra in Alaska are. In order to do so, the five most important ecosystem services were selected and further investigated. The result is a framework that enables others to apply the methods used in this study on their specific case.
As seen in table 7, the best land use for biodiversity, carbon sequestration and water quality regulation is boreal forest, while agriculture seems to be the best land use for food and raw material production. Furthermore, agricultural land seems to be the best local option while boreal forest provides important local and global services. Therefore, the best land use for changing low arctic tundra in Alaska depends on the perspective of the stakeholders.
Since a uniform answer cannot be provided, stakeholders should use the framework created in this research to determine the best land use for their specific area. The produced framework should mainly be used by parties that will directly gain value from changed land use, such as local communities or larger county/state-like communities. Policy makers have to find a balance between ecological and economic and local and global effects of the different possible land uses in changing low arctic tundra. The framework provided in this research will enable them to choose which land use is most beneficial for their specific piece of land and purpose.
Discussion
It is important to note that every stakeholder values their interests differently. Therefore, the results of this research will be interpreted differently and will be used differently per stakeholder. However, the results are displayed in such a way that a clear overview is presented, enabling stakeholders to make a well-considered decision.
Boreal forest Agricultural land Best outcome Scale
Biodiversity High Relatively low Boreal forest Local & global
Carbon sequestration
($/hectare)
16545 - 18650 9859 - 16946 Boreal forest Global
Food production
($/hectare) 0.33 - 5.50 13282 or 3224 Agricultural land Local
Raw material production ($/hectare)
78.02 1016 Agricultural land Local
Water quality
regulation High to neutral Negative Boreal forest Local
23
Another point of importance is the selection of ecosystem services. In this report, five were selected amongst many more ecosystem services. These were deemed to be the most important services and are prone to change. Other studies and future studies might disagree on the selection of services chosen in this report, and it is by no means certain that the chosen services are the best services. In the scope of this research, the amount of selected services was limited, as was the research into other possible land uses besides boreal forest and agricultural land. Therefore, a slight subjectivity might be present in this research.
Moreover, in this report many qualitative but also quantitative descriptions have been given about the economic values of ecosystem services. These descriptions were given with the best possible accuracy. However, true values are hard to estimate. A clarifying example is the calculation of the value by food production on agricultural land.
The value of food production on agricultural land, calculated using direct market valuation, is based solely on the total income of one hectare agricultural land. Thus, the costs are not accounted for. However, NASS (2016) states that in 2012 the average expenses per Alaskan farm were $73,383 while the income was $11,271. This provides an insight in the potential economic feasibility of farming in Alaska. The existence of many farms is probably dependent on the level of subsidies provided by the government. Furthermore, this could be an explanation for the difference of the value of food production on agricultural land calculated by the different economic valuation techniques. Since the replacement cost method makes use of ‘supermarket’ prices, while the direct market valuation method makes use of wholesale prices, the value calculated using the former was expected to be higher. However, the results are reversed. The value of agricultural land has been calculated to be $13282 per hectare when using direct market valuation and $3224 per hectare when using the replacement cost method. This could be due to the disregarding of the costs.
It is also important to realize that in some scenarios the use of one ecosystem service impedes the use of another. For instance, agricultural land could be used for food or raw material production, not both.
Lastly, this framework calls for additional research into this topic. Due to climate change, a biome shift will occur, drastically decreasing the tundra area. Therefore, necessity to expand on this research is present. Global carbon levels need to be controlled and food security is a pressing issue worldwide. Therefore, local stakeholders will need as much accurate information as possible to determine their future actions.
24
References
Arctic Climate Impact Assessment (2004). Impact of a Warming Arctic: Arctic Climate Impact
Assessment. (No. 1). Cambridge University Press.
Ackerman, F., & Stanton, E. (2012). Climate risks and carbon prices: Revising the social cost of carbon. Economics: The Open-Access, Open-Assessment E-Journal, 6, 10.
AFPC (2012). Alaska Food Policy Council strategic plan 2012-2015. (No. 1) Alaska Department of Fish and Game (2015). Alaska wildlife action plan. Juneau.
Alaska Department of Natural Resources, Division of Agriculture (2014). Alaska grown source book 2014-2015. Accessed on: 2016/04/12, from www.adfg.alaska.gov.
Anisimov, O.A., Vaughan, D.G., Callaghan, T.V., Furgal, C., Marchant, H., Prowse, T.D., Vilhjálmsson, H. and Walsh, J.E. (2007). Polar regions (Arctic and Antarctic). Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds., Cambridge University
Press, Cambridge, 653-685.
Barsdate, R. J., & Alexander, V. (1975). The nitrogen balance of arctic tundra: pathways, rates, and environmental implications. Journal of Environmental Quality, 4(1), 111-117.
Betts, R. A. (2000). Offset of the potential carbon sink from boreal forestation by decreases in surface albedo. Nature, 408(6809), 187-190
Bliss, L. C., Heal, O. W., & Moore, J. J. (1981). Tundra ecosystems: a comparative analysis (Vol. 25). CUP Archive.
Chapin, E.S., Shaver, G.R., Giblin, A.E., Nadelhoffer, K.J. & Laundre, J.A. (1995). Responses of Arctic tundra to experimental and observed changes in climate. Ecology, 76(3), 694-711. Chapin III, F. S., Zavaleta, E. S., Eviner, V. T., Naylor, R. L., Vitousek, P. M., Reynolds, H. L., & Mack, M. C. (2000). Consequences of changing biodiversity. Nature, 405(6783), 234-242. Davidson, E. A., Janssens, I.A. (2006) Temperature sensitivity of soil carbon decomposition and feedbacks to climate change. Nature, 440, 165-173.
Davis, M. A. (2009). Invasion biology. Oxford University Press on Demand.
DeLong, D. C. (1996). Defining biodiversity. Wildlife Society Bulletin (1973-2006), 24(4), 738-749.
Donoghue, M.J. & Edwards, E.J. (2014). Biome Shifts and Niche Evolution in Plants. Annual Review of Ecology, Evolution and Systematics 45:547–72.
Fazzino, D. V. & Loring, P. A. (2009). From crisis to cumulative effects: Food security challenges in Alaska. NAPA Bulletin, 32(1), 152-177.
Fischer, G., Hizsnyik, E., Prieler, S., & Wiberg, D. (2010). Scarcity and abundance of land resources: competing uses and the shrinking land resource base. SOLAW Background Thematic Report-TR02. FAO, Rome.
25
Fischlin, A., Midgley, G.F., Price, J.T., Leemans, R., Gopal, B., Turley, C., Rounsevell, M.D.A., Dube, O.P., Tarazona, J. and Velichko, A.A. (2007). Ecosystems, their properties, goods, and services. Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of
Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Parry, M.L., Canziani, O.F., Palutikof, J.P., Van der Linden, P.J. & Hanson, C.E.,
Eds., Cambridge University Press, Cambridge, 211-272.
Forest Service (2009). Common trees of alaska. United States Department of Agriculture. Accessed on: 2016/04/21, from www.fs.usda.gov.
Guo, L., Ping, C. L., & Macdonald, R. W. (2007). Mobilization pathways of organic carbon from permafrost to arctic rivers in a changing climate. Geophysical Research Letters, 34(13). Holden, J. (2013). Water resources: an integrated approach. Routledge.
Interagency Working Group on Social Cost of Carbon (2010). Social Cost of Carbon for
Regulatory Impact Analysis Under Executive Order 12866. Washington, DC: U.S. Department
of Energy.
Krauss, M. E., Holton, G., Kerr, J. & West, C. (2011). Indigenous peoples and languages of alaska. Retrieved from http://www.uaf.edu
Lele, S., Springate-Baginski, O., Lakerveld, R., Deb, D. & Dash, P. (2013). Ecosystem Services: Origins, Contributions, Pitfalls, and Alternatives. Conservat Soc 11:343-58.
Lenat, D. R. (1984). Agriculture and stream water quality: a biological evaluation of erosion control practices. Environmental management, 8(4), 333-343.
Lichtenthaler, H. K., Buschmann, C., Döll, M., Fietz, H. J., Bach, T., Kozel, U., ... & Rahmsdorf, U. (1981). Photosynthetic activity, chloroplast ultrastructure, and leaf characteristics of high-light and low-high-light plants and of sun and shade leaves. Photosynthesis research, 2(2), 115-141.
Lindroth, A., Grelle, A., & Morén, A. S. (1998). Long‐term measurements of boreal forest carbon balance reveal large temperature sensitivity. Global Change Biology, 4(4), 443-450. Loring, P. A., & Gerlach, S. C. (2009). Food, culture, and human health in Alaska: an integrative health approach to food security. Environmental Science & Policy, 12(4), 466-478. Loring, P. A., & Gerlach, S. C. (2015). Searching for Progress on Food Security in the North American North: A Research Synthesis and Meta-analysis of the Peer-Reviewed Literature.
ARCTIC, 68(3), 380-392.
McGill, B. J., Enquist, B. J., Weiher, E., & Westoby, M. (2006). Rebuilding community ecology from functional traits. Trends in ecology & evolution, 21(4), 178-185.
McIntyre, T. (2003). Phytoremediation of heavy metals from soils. In Phytoremediation (pp. 97-123). Springer Berlin Heidelberg.
Millennium Ecosystem Assessment, 2005. Ecosystems and Human Well-being: Synthesis. Island Press, Washington, DC.
Mucina, L. (1997). Classification of Vegetation: Past, Present and Future. Journal of
26
Myers, N. (1997). The world's forests and their ecosystem services. Nature's Services: societal
dependence on natural ecosystems, 215-235.
NatureServe (2015). NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Accessed on: 2016/04/18, from http://explorer.natureserve.org.
Nilsson, S., & Schopfhauser, W. (1995). The carbon-sequestration potential of a global afforestation program. Climatic change, 30(3), 267-293.
Nordhaus, W. D. (2007). A review of the" stern review on the economics of climate change".
Journal of Economic Literature, , 686-702.
Nordhaus, W. D. (2014). Estimates of the social cost of carbon: Concepts and results from the DICE-2013R model and alternative approaches. Journal of the Association of Environmental
and Resource Economists, 1(1/2), 273-312.
Nunes, P. A., & van den Bergh, J. C. (2001). Economic valuation of biodiversity: sense or nonsense?. Ecological economics, 39(2), 203-222.
Oechel, W. C., Hastings, S. J., Vourlrtis, G., Jenkins, M., Riechers, G., & Grulke, N. (1993). Recent change of arctic tundra ecosystems from a net carbon dioxide sink to a source. Nature,
361(6412), 520-523.
Osborne, T. (1994). Great Grey Owl. Alaska Department of Fish and Game. Accessed on: 2016/04/20, from www.adfg.alaska.org.
Power, A. G. (2010). Ecosystem services and agriculture: tradeoffs and synergies.
Philosophical Transactions of the Royal Society of London B: Biological Sciences, 365(1554),
2959-2971.
Reeves, D. W. (1997). The role of soil organic matter in maintaining soil quality in continuous cropping systems. Soil and Tillage Research, 43(1), 131-167.
Rekacewicz, P. (2005). Total and indigenous populations of the Arctic: Alaska.
UNEP/GRID-Arendal. Accessed on: 2016/04/20, from www.grida.no. Copied from: United States department of commerce (1993).
Richards, A. J. (2001). Does low biodiversity resulting from modern agricultural practice affect crop pollination and yield?. Annals of Botany, 88(2), 165-172.
Sabine, C.L., Heimann, M., Artaxo, P., Bakker, D.C.E., Chen, C.T.A., Field C.B. & Gruber, N. (2004). Current status and past trends of the global carbon cycle. Global Carbon Cycle: Integrating Humans, Climate, and the Natural World, C.B. Field And M.R. Raupach, Eds.,
Island Press,Washington, District of Columbia, 17-44.
Salt, D. E., Blaylock, M., Kumar, N. P., Dushenkov, V., Ensley, B. D., Chet, I., & Raskin, I. (1995). Phytoremediation: a novel strategy for the removal of toxic metals from the environment using plants. Nature biotechnology, 13(5), 468-474.
Salt, D. E., Smith, R. D., & Raskin, I. (1998). Phytoremediation. Annual review of plant biology,
27
Schnoor, J. L., Light, L. A., McCutcheon, S. C., Wolfe, N. L., & Carreia, L. H. (1995). Phytoremediation of organic and nutrient contaminants. Environmental Science &
Technology, 29(7), 318A-323A.
Smith, R. L., Smith, T. M., Hickman, G. C., & Hickman, S. M. (2006). Elements of ecology. Benjamin Cummings.
State of Alaska (2016). Tundra. Accessed on: 2016/02/25, from: www.adfg.alaska.gov. Stein, B.A. (2002). States of the Union: Ranking America’s Biodiversity. Arlington, Virginia:
NatureServe.
Stow, D. A., Hope, A., McGuire, D., Verbyla, D., Gamon, J., Huemmrich, F., ... & Hinzman, L. (2004). Remote sensing of vegetation and land-cover change in Arctic Tundra Ecosystems.
Remote Sensing of Environment, 89(3), 281-308.
Swinton, S. M., Lupi, F., Robertson, G. P., & Hamilton, S. K. (2007). Ecosystem services and agriculture: cultivating agricultural ecosystems for diverse benefits. Ecological economics,
64(2), 245-252.
Tedrow, J. C. F. (1968). Pedogenic gradients of the polar regions. Journal of Soil Science,
19(1), 197-203.
Tol, R. S. (2008). The social cost of carbon: Trends, outliers and catastrophes. Economics:
The Open-Access, Open-Assessment E-Journal, 2.
United States Department of Agriculture. (2016). Official USDA Alaska and Hawaii Thrifty
Food Plans: Cost of Food at Home (2nd half 2015).
United States Department of Agriculture's National Agricultural Statistics Service. (2016). 2015
State Agriculture Overview: Alaska. Accessed on: 2016/04/22, from
http://www.nass.usda.gov/Quick_Stats/Ag_Overview/stateOverview.php?state=ALASKA Van der Perk, M. (2013). Soil and water contamination. CRC Press.
Viereck, L. and Little, E. L. (1972). Alaska trees and shrubs. Forest Service & United States Department of Agriculture.
Vollenweider, R. A. (1968). Scientific fundamentals of the eutrophication of lakes and flowing waters, with particular reference to nitrogen and phosphorous as factors in eutrophication. Walker, M. D., Wahren, C. H., Hollister, R. D., Henry, G. H., Ahlquist, L. E., Alatalo, J. M., ... & Epstein, H. E. (2005). Plant community responses to experimental warming across the tundra biome. Proceedings of the National Academy of Sciences, 103(5), 1342-1346.
Wilson, E.O. (1988). Biodiversity. National Academy of Sciences, Smithsonian Institution. Young, A. M., & Larson, B. M. (2011). Clarifying debates in invasion biology: a survey of invasion biologists. Environmental research, 111(7), 893-898.
Zhang, W., Ricketts, T. H., Kremen, C., Carney, K., & Swinton, S. M. (2007). Ecosystem services and dis-services to agriculture. Ecological economics, 64(2), 253-260.
Zimov, S.A., Schuur, E.A.G. and Chapin, F.S. (2006). Permafrost and the global carbon budget. Science, 312, 1612-1613.
28
Appendix A - Glossary
Avoided Cost (AC)
This technique can be applied to ecosystems with regulating functions that avoid costs, which would have occurred in the absence of those ecosystem services. Common example is the presence of a forest close to shore that functions as flood control and therefore avoids costs to the infrastructure.
Biodiversity
Biodiversity is a term that is difficult to specify. In figure 1, several different definitions of biodiversity are given with the paper in which it was used. The most commonly used definition of biodiversity is the species richness of an area, ecosystem or biome (DeLong, 1996). The term species in biology means a population or multiple populations in which a free gene flow exist under natural conditions (Wilson, 1988).
Figure 1. Different definitions of biodiversity. Reprinted from ‘Defining biodiversity’ by DeLong, 1996. The total biodiversity of the world can only be speculated about, since there most likely are large amount of species not yet discovered. However, in the late 80’s about 1.4 million living species of different kinds of organisms were described and the assumed absolute number of species was between the 5 and 300 million (Wilson, 1988).
