Land-use changes and carbon sequestration through the twentieth century in a Mediterranean mountain ecosystem: Implications for land management

Ecosystems in the western Mediterranean basin have undergone intense changes in land use throughout the centuries, resulting in areas with severe alterations. Today, most these areas have become sensitive to human activity, prone to profound changes in land-use configuration and ecosystem services. A consensus exists amongst stakeholders that ecosystem services must be preserved but managerial strategies that help to preserve them while ensuring sustainability are often inadequate. To provide a basis for measuring implications of land-use change on carbon sequestration services, changes in land use and associated carbon sequestration potential throughout the 20th century in a rural area at the foothills of the Sierra Nevada range (SE Spain) were explored. We found that forest systems replaced dryland farming and pastures from the middle of the century onwards as a result of agricultural abandonment and afforestation programs. The area has always acted as a carbon sink with sequestration rates ranging from 28,961 t CO₂ year^?1 in 1921 to 60,635 t CO₂ year^?1 in 1995, mirroring changes in land use. Conversion from pastures to woodland, for example, accounted for an increase in carbon sequestration above 30,000 t CO₂ year^?1 by the end of the century. However, intensive deforestation would imply a decrease of approximately 66% of the bulk CO₂ fixed. In our study area, woodland conservation is essential to maintain the ecosystem services that underlie carbon sequestration. Our essay could inspire policymakers to better achieve goals of increasing carbon sequestration rates and sustainability within protected areas.     

Trade-Based Carbon Sequestration Accounting

This article describes and illustrates an accounting method to assess and compare early carbon sequestration investments and trades on the basis of the number of standardized CO₂ emission offset credits they will provide. The gold standard for such credits is assumed to be a relatively riskless credit based on a CO₂ emission reduction that provides offsets against CO₂ emissions on a one-for-one basis. The number of credits associated with carbon sequestration needs to account for time, risk, durability, permanence, additionality, and other factors that future trade regulators will most certainly use to assign official credits to sequestration projects. The method that is presented here uses established principles of natural resource accounting and conventional rules of asset valuation to score projects. A review of 20 early voluntary United States based CO₂ offset trades that involve carbon sequestration reveals that the assumptions that buyers, sellers, brokers, and traders are using to characterize the economic potential of their investments and trades vary enormously. The article develops a universal carbon sequestration credit scoring equation and uses two of these trades to illustrate the sensitivity of trade outcomes to various assumptions about how future trade auditors are likely to score carbon sequestration projects in terms of their equivalency with CO₂ emission reductions. The article emphasizes the importance of using a standard credit scoring method that accounts for time and risk to assess and compare even unofficial prototype carbon sequestration trades. The scoring method illustrated in this article is a tool that can protect the integrity of carbon sequestration credit trading and can assist buyers and sellers in evaluating the real economic potential of prospective trades. Published online     

Social, economic, and ecological impacts of the "Grain for Green" project in China: a preliminary case in Zhangye, Northwest China

This paper provides applications of the integrated assessment (IA) approach in a case study in the Heihe River Basin of Northwest China. Some socio-economic and ecological impact results of forestry land use scenarios are presented in the paper. While seven types of land use scenarios for carbon sequestration purposes were considered for the IA applications, this paper mainly presents impacts of land use scenarios within the Grain for Green (GFG) category [see Yin et al., this volume]. China's national Grain for Green Project was implemented in order to protect and improve ecosystems, while allowing an evolution of agricultural management practices compatible with raising peasants' incomes. Zhangye Prefecture, located in the Heihe River Basin of an arid area in Northwest China, was chosen as the investigation site of the IA case study. Based on fundamental orientation theory, the social sustainability impacts of GFG land use options were assessed. Between 2002 and 2004, the GFG project brought US$23.56 million yuan in net income to the prefecture's peasants. Project implementation resulted in a 1.71 Gg increase in net primary productivity (NPP), as well as a 44.36 Gg rise in net ecosystem productivity (NEP). This suggested that, in Zhangye Prefecture, the Grain for Green Project could enhance the sustainability and stability of the local society, increase peasants' net income, as well as protect and remediate local ecosystems.     

Carbon Sequestration in Dryland Ecosystems

Drylands occupy 6.15 billion hectares (Bha) or 47.2% of the worlds land area. Of this, 3.5 to 4.0 Bha (57%–65%) are either desertified or prone to desertification. Despite the low soil organic carbon (SOC) concentration, total SOC pool of soils of the drylands is 241 Pg (1 Pg = petagram = 10¹⁵ g = 1 billion metric ton) or 15.5% of the worlds total of 1550 Pg to 1-meter depth. Desertification has caused historic C loss of 20 to 30 Pg. Assuming that two-thirds of the historic loss can be resequestered, the total potential of SOC sequestration is 12 to 20 Pg C over a 50-year period. Land use and management practices to sequester SOC include afforestation with appropriate species, soil management on cropland, pasture management on grazing land, and restoration of degraded soils and ecosystems through afforestation and conversion to other restorative land uses. Tree species suitable for afforestation in dryland ecosystems include Mesquite, Acacia, Neem and others. Recommended soil management practices include application of biosolids (e.g., manure, sludge), which enhance activity of soil macrofauna (e.g., termites), use of vegetative mulches, water harvesting, and judicious irrigation systems. Recommended practices of managing grazing lands include controlled grazing at an optimal stocking rate, fire management, and growing improved species. The estimated potential of SOC sequestration is about 1 Pg C/y for the world and 50 Tg C/y for the U.S. This potential of dryland soils is relevant to both the Kyoto Protocol under UNFCCC and the U.S. Farm Bill 2002.

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Global sustainability: Toward measurement

The widespread interest in the concept of sustainable environment and development has been accompanied by the need to develop useful systems of measurement. We discuss the use of indicators which might be used to assess such conditions. Our characteristics, or criteria, for desirable global sustainability indicators are:

sensitivity to change in time

sensitivity to change across space or within groups

predictive ability

availability of reference or threshold values

ability to measure reversibility or controllability

appropriate data transformation

integrative ability

relative ease of collection and use

We discuss the basis of these characteristics, and examine two categories of indicators (soil erosion and population) and two specific indicators (physical quality of life index and energy imports as a percentage of consumption) for their value as sustainability measures.     

From Forest Landscape to Agricultural Landscape in the Developing Tropical Country of Malaysia: Pattern,Process, and Their Significance on Policy

Agricultural expansion and deforestation are spatial processes of land transformation that impact on landscape pattern. In peninsular Malaysia, the conversion of forested areas into two major cash crops—rubber and oil palm plantations—has been identified as driving significant environmental change. To date, there has been insufficient literature studying the link between changes in landscape patterns and land-related development policies. Therefore, this paper examines: (i) the links between development policies and changes in land use/land cover and landscape pattern and (ii) the significance and implications of these links for future development policies. The objective is to generate insights on the changing process of land use/land cover and landscape pattern as a functional response to development policies and their consequences for environmental conditions. Over the last century, the development of cash crops has changed the country from one dominated by natural landscapes to one dominated by agricultural landscapes. But the last decade of the century saw urbanization beginning to impact significantly. This process aligned with the establishment of various development policies, from land development for agriculture between the mid 1950s and the 1970s to an emphasis on manufacturing from the 1980s onward. Based on a case study in Selangor, peninsular Malaysia, a model of landscape pattern change is presented. It contains three stages according to the relative importance of rubber (first stage: 1900–1950s), oil palm (second stage: 1960s–1970s), and urban (third stage: 1980s–1990s) development that influenced landscape fragmentation and heterogeneity. The environmental consequences of this change have been depicted through loss of biodiversity, geohazard incidences, and the spread of vector-borne diseases. The spatial ecological information can be useful to development policy formulation, allowing diagnosis of the country’s “health” and sustainability. The final section outlines the usefulness of landscape analysis in the policy-making process to prevent further fragmentation of the landscape and forest loss in Malaysia in the face of rapid economic development.

Carbon isotope ratios in logged and unlogged boreal forests: Examination of the potential for determining wildlife habitat use

Due to assimilation of recycled CO₂ from litter decomposition and photosynthetic changes in carbon fractionation at low light levels, the foliage at the base of a forest is often more depleted in¹³C compared to that exposed to the atmosphere in either the canopy or in open clearings. This is referred to as the canopy effect. African research has indicated that these habitat differences in foliar ¹³C can be substantial enough to affect the carbon isotope ratios of resident fauna. Previous work documenting a 30-year chronology on moose teeth from Isle Royale National Park indicated a progressive depletion in¹³C and suggested that this could be due to forest regrowth following extensive burning. The present study examined the assumption implicit in this hypothesis that foliar ¹³C varies between open and closed boreal forest sites. I found a marginal canopy effect of 2 ¹³C difference between upper canopy and ground flora for a forest in northwestern Ontario and an average difference of 1.2 in under- and mid-story vegetation between closed forests and open clear-cuts. Because of these small differences, the utility of carbon isotope analysis in quantifying temporally integrated exploitation of deforested habitats will be low for northern boreal locations. In denser forests, such as those in the tropics or western North American where the canopy effect can be expected to be much greater, ¹³C analysis may still offer some promise for determining selection by wildlife of disturbed habitats.     

Land use change effects on forest carbon cycling throughout the southern United States

We modeled the effects of afforestation and deforestation on carbon cycling in forest floor and soil from 1900 to 2050 throughout 13 states in the southern United States. The model uses historical data on gross (two-way) transitions between forest, pasture, plowed agriculture, and urban lands along with equations describing changes in carbon over many decades for each type of land use change. Use of gross rather than net land use transition data is important because afforestation causes a gradual gain in carbon stocks for many decades, while deforestation causes a much more rapid loss in carbon stocks. In the South-Central region (Texas to Kentucky) land use changes caused a net emission of carbon before the 1980s, followed by a net sequestration of carbon subsequently. In the Southeast region (Florida to Virginia), there was net emission of carbon until the 1940s, again followed by net sequestration of carbon. These results could improve greenhouse gas inventories produced to meet reporting requirements under the United Nations Framework Convention on Climate Change. Specifically, from 1990 to 2004 for the entire 13-state study area, afforestation caused sequestration of 88 Tg C, and deforestation caused emission of 49 Tg C. However, the net effect of land use change on carbon stocks in soil and forest floor from 1990 to 2004 was about sixfold smaller than the net change in carbon stocks in trees on all forestland. Thus land use change effects and forest carbon cycling during this period are dominated by changes in tree carbon stocks.     

Implications of Land Use Changes on Carbon Dynamics and Sequestration—Evaluation from Forestry Datasets, India

Forests and soils are a major sink of carbon, and land use changes can affect the magnitude of above ground and below ground carbon stores and the net flux of carbon between the land and the atmosphere. Studies on methods for examining the future consequences of changes in patterns of land use change and carbon flux gains importance, as they provide different options for CO₂ mitigation strategies. In this study, a simulation approach combining Markov chain processes and carbon pools for forests and soils has been implemented to study the carbon flows over a period of time. Markov chains have been computed by converting the land use change and forestry data of India from 1997 to 1999 into a matrix of conditional probabilities reflecting the changes from one class at time t to another class time t+1. Results from Markov modeling suggested Indian forests as a potential sink for 0.94 Gt carbon, with an increase in dense forest area of about 75.93 Mha and decrease of about 3.4 Mha and 5.0 Mha in open and scrub forests, if similar land use changes that occurred during 1997–1999 would continue. The limiting probabilities suggested 34.27 percent as dense forest, 6.90 as open forest, 0.4 percent mangrove forest, 0.1 percent scrub and 58 percent as non-forest area. Although Indian forests are found to be a potential carbon sink, analysis of results from transition probabilities for different years till 2050 suggests that, the forests will continue to be a source of about 20.59 MtC to the atmosphere. The implications of these results in the context of increasing anthropogenic pressure on open and scrub forests and their contribution to carbon source from land use change and forestry sector are discussed. Some of the mitigation aspects to reduce greenhouse gas emissions from land use change and forestry sector in India are also reviewed in the study.     

Prevalence of Conservation Design in an Agriculture-Dominated Landscape: The Case of Northern Indiana

We examined the prevalence of residential development that occurs with consideration of the natural features of the site, known as conservation design, within county-level planning jurisdictions across Northern Indiana. Using data from telephone interviews with representatives of planning departments, jurisdictions were ranked based on reported use of conservation design. Three categories of use emerged from the data: no use, use of individual practices associated with conservation design, and integration of multiple conservation design practices. Qualitative data analysis revealed that conservation design practices were not being used widely and, when used, were often used to fulfill stormwater requirements. Statistical analysis, using data from interviews, spatial data sets, and the U.S. Census Bureau, identified several significant positive predictors of the levels of conservation design use including conversion of forest or agricultural land cover to urban uses and education levels in the jurisdiction. Many of the interviewees noted that agricultural land is perceived to meet open space needs within their counties. Given that agricultural land does not fully meet all ecosystem needs, education about the benefits of other types of open space is suggested.

Forest carbon management in the United States: 1600-2100

This paper reviews the effects of past forest management on carbon stocks in the United States, and the challenges for managing forest carbon resources in the 21st century. Forests in the United States were in approximate carbon balance with the atmosphere from 1600-1800. Utilization and land clearing caused a large pulse of forest carbon emissions during the 19th century, followed by regrowth and net forest carbon sequestration in the 20th century. Recent data and knowledge of the general behavior of forests after disturbance suggest that the rate of forest carbon sequestration is declining. A goal of an additional 100 to 200 Tg C/yr of forest carbon sequestration is achievable, but would require investment in inventory and monitoring, development of technology and practices, and assistance for land managers.     

Effects of Changing Forest and Impervious Land Covers on Discharge Characteristics of Watersheds

Effects of changing patterns of forest and impervious land covers on hydrologic regimes of watersheds were evaluated for urban and rural areas of the lower Cedar River drainage near Seattle, Washington. Land cover characterizations were used in a spatially explicit hydrology model to assess effects of land covers on watershed hydrology during presettlement conditions (full forest cover), 1991 and 1998. For the presettlement to 1991 period, urban watersheds showed decreases in forest covers (range 63% to 83%) and increases in impervious surfaces (range 43% to 71%). Rural watersheds showed similar patterns but smaller changes, with forest covers decreasing (range 28% to 34%) and impervious surfaces increasing (range 8% to 15%). For the 1991 and 1998 period, changes in forest covers for urban and rural watershed were <24%, with losses in some watersheds and regeneration in others. Impervious surfaces continued to increase, but increases were larger in rural (range 38% to 60%) than in urban watersheds (range 4% to 27%). Flood-frequency curves indicated that discharge rates (m sec^–1) for all watersheds were higher in 1991 and 1998 than historical and suggested that chances for floods increase because of changing land covers. The largest increases in discharge rates were in urban watersheds, with rates for 2-year, 10-year, and 25-year recurrence intervals being more than two times greater than the rate during historical conditions. Changes in flow regimes were indicated by presettlement discharge levels of less frequent recurrence intervals (10-year and 25-year) occurring in posturbanization times (1991 and 1998) during more frequent intervals (2-year and 10-year). Normalized flows (m yr^–1) of watersheds for 2-year, 10-year, and 25-year recurrence intervals indicate how flow regimes in 1991 and 1998 can change as functions of different areas of land covers. During 1991 and 1998, abrupt increases in flows occurred when forest covers were low (range 17% to 37%) and impervious surfaces were >46%. In contrast, the lowest flows occurred when forest covers were most extensive (range 59% to 81%) and impervious surfaces were <23%. We conclude that our use of spatial characterizations of impervious surfaces and forested covers in a spatially explicit hydrology model provides a robust approach for revealing how variations in different types and spatial distributions of land covers can affect flood regimes and flows of different watersheds.     

An Empirical Evaluation of Private Landowner Participation in Voluntary Forest Conservation Programs

The use of voluntary programs targeting resource conservation on private land has become increasingly prevalent in environmental policy. Voluntary programs potentially offer significant benefits over regulatory and market-based approaches. This article examines the factors affecting landowner participation in voluntary forest conservation programs using a combination of parcel-level GIS and remotely sensed data and semi-structured interviews of landowners in Monroe County, Indiana. A logistic regression model is applied to determine the probability of participation based on landowner education, membership in other non-forest voluntary programs, dominant land use activity, parcel size, distance from urban center, land resource portfolios, and forest cover. Both land use activity and the spatial configuration of a landholder’s resource portfolio are found to be statistically significant with important implications for the design and implementation of voluntary programs.

Non-Point-Source Impacts on Stream Nutrient Concentrations Along a Forest to Urban Gradient

We conducted statistical analyses of a 10-year record of stream nutrient and sediment concentrations for 17 streams in the greater Seattle region to determine the impact of urban non-point-source pollutants on stream water quality. These catchments are dominated by either urban (22–87%) or forest (6–73%) land cover, with no major nutrient point sources. Stream water phosphorus concentrations were moderately strongly (r²=0.58) correlated with catchment land-cover type, whereas nitrogen concentrations were weakly (r²=0.19) and nonsignificantly (at < 0.05) correlated with land cover. The most urban streams had, on average, 95% higher total phosphorus (TP) and 122% higher soluble reactive phosphorus (SRP) and 71% higher turbidity than the most forested streams. Nitrate (NO₃), ammonium (NH₄), and total suspended solids (TSS) concentrations did not vary significantly with land cover. These results suggest that urbanization markedly increased stream phosphorus concentrations and modestly increased nitrogen concentrations. However, nutrient concentrations in Seattle region urban streams are significantly less than those previously reported for agricultural area streams.     

Where the Waters Divide: First Nations,Tainted Water and Environmental Justice in Canada

Abstract

We have survived Canada's assault on our identity and our rights … Our survival is a testament to our determination and will to survive as a people. We are prepared to participate in Canada's future—but only on the terms that we believe to be our rightful heritage.

Wallace Labillois, Council of Elders, Kingsclear, New Brunswick

This paper argues for a strengthening of the theoretical relationship between neo-liberalism and environmental justice. Empirical research involving First Nations communities in southwestern Ontario suggests that neo-liberal reforms introduced in the mid-1990s were particularly discriminatory against Canada's indigenous peoples, serving to exacerbate historical disparities in health, environment pollution, and well-being. In particular, under neo-liberal reform in Ontario, recognition of environmental injustices has become much more difficult for First Nations communities. Furthermore, this ‘new’ form of environmental governance has broadly reduced legitimate opportunities for First Nations to participate in environmental governance that affects their health and welfare. In short, this research supports a widening of the definition of environmental justice advocated by David Schlosberg and others (Environmental Politics, 13(3) (2004), pp. 517–540; Agyeman, Bullard and Evans 2003 Agyeman, J., Bullard, R. D. and Evans, B. 2003a. “Joined-up thinking: bringing together sustainability, environmental justice and equity”. In Just Sustainabilities: Development in an Unequal World, Edited by: Agyeman, J., Bullard, R. D. and Evans, B. Cambridge, MA: MIT Press.  [Google Scholar]; Akwesasne Task Force on the Environment, Research Advisory committee 1997; Di Chiro 1998 Di Chiro, Giovanna. 1998. “Environmental Justice from the Grassroots: Reflections on History, Gender and Expertise”. In The Struggle for Ecological Democracy: Environmental Justice Movements in the United States, Edited by: Faber, D. NY: Guilford.  [Google Scholar]) if we are to understand the subtle, complex and multiple ways that this new form of environmental governance is particularly harmful to marginalized groups, such as First Nations in Canada.     

The Political Economy of Land Grabs in Malawi: Investigating the Contribution of Limphasa Sugar Corporation to Rural Development

Though a recent phenomenon, land grabs have generated considerable debate that remains highly polarized. In this debate, one view presents land deals as a path to sustainable and transformative rural development through capital accumulation, infrastructural development, technology transfer, and job creation while the alternative view sees land grabs as a new wave of neo-colonization, exploitation, and domination. The underlying argument, at least theoretically, is that international land deals unlock the much needed capital to accelerate the achievement of sustainable and transformative rural development in developing countries. It is against this backdrop that this paper examines the contribution of large scale land deals in Malawi to rural development by employing the political economy perspective using the Limphasa Sugar Corporation as a case study with particular focus on the nature and interest of the actors involved; the legal framework supporting large scale land deals; major individual and community benefits; and the extent to which these large land deals can indeed bring about sustainable and transformative rural development. The findings of this article demonstrate that large scale land deals present short term benefits to local communities such as capital for rural development; technology transfer and job creation in exchange for the priceless economic and social capital that local people depend upon; destruction of local social systems; deepening of local communities’ vulnerability to economic shocks; and the entrenchment of community dependence that may in the long run result in social and political unrest.     

An ecological analysis of predominant land uses in the Brazilian Amazon

Summary The land uses that now predominate in Brazil's Amazon Region are unlikely to produce sustainable yields. They also tend to close off potentially sustainable alternative uses. Cattle pasture — either productive or abandoned — now occupies most deforested land. Small farmers plant pasture after using the land for a year or two under annual crops, while large cattle ranches plant pasture directly after clearing. The principal motive for planting pasture is often its low cost and high effectiveness as a means of securing speculative land claims — not beef production.Pasture and cattle yields are low and, after use for about a decade, the planted grasses are out-competed by secondary forest species or inedible grasses. Depletion of available phosphorus in the soil is a major cause of yield decline; Brazil's relatively modest phosphorus deposits, virtually all of which are outside of Amazonia, make fertiliser use not feasible for the vast areas now rapidly being converted to pasture. Converting a substantial portion of Amazonia to pasture would have potential climatic effects. Areas that can be planted in annual and perennial crops are restrained by world markets, as well as by soil quality and Brazil's limited stocks of the inputs needed for intensive agriculture.Recent initiatives for agricultural-ecological in Brazil's Amaoznian states could be a first step toward more rational land use. Immediate measures are needed to slow deforestation, to discourage unsustainable uses and to make sustainable alternatives profitable.Professor Philip Fearnside is currently Research Professor in the Department of Ecology at the National Institute for Research in the Amazon. The paper has been modified from an earlier version presented at the International Symposium on Alternatives to Deforestation held in Belém, Pará, Brazil in January 1988.     

Effects of sandy desertified land rehabilitation on soil carbon sequestration and aggregation in an arid region in China

The rehabilitation of sandy desertified land in semi-arid and arid regions has a great potential to increase carbon sequestration and improve soil quality. Our objective was to investigate the changes in the soil carbon pool and soil properties of surface soil (0–15 cm) under different types of rehabilitation management. Our study was done in the short-term (7 years) and long-term (32 years) desertification control sites in a marginal oasis of northwest China. The different management treatments were: (1) untreated shifting sand land as control; (2) sand-fixing shrubs with straw checkerboards; (3) poplar (Populus gansuensis) shelter forest; and (4) irrigated cropland after leveling sand dune. The results showed that the rehabilitation of severe sandy desertified land resulted in significant increases in soil organic C (SOC), inorganic C, and total N concentrations, as well as enhanced soil aggregation. Over a 7-year period of revegetation and cultivation, SOC concentration in the recovered shrub land, forest land and irrigated cropland increased by 4.1, 14.6 and 11.9 times compared to the control site (shifting sand land), and increased by 11.2, 17.0 and 23.0 times over the 32-year recovery period. Total N, labile C (KMnO₄–oxidation C), C management index (CMI) and inorganic C (CaCO₃–C) showed a similar increasing trend as SOC. The increased soil C and N was positively related to the accumulation of fine particle fractions. The accumulation of silt and clay, soil C and CaCO₃ enhanced the formation of aggregates, which was beneficial to mitigate wind erosion. The percentage of >0.25 mm dry aggregates increased from 18.0% in the control site to 20.0–87.2% in the recovery sites, and the mean weight diameter (MWD) of water-stable aggregates significantly increased, with a range of 0.09–0.30 mm at the recovery sites. Long-term irrigation and fertilization led to a greater soil C and N accumulation in cropland than in shrub and forest lands. The amount of soil C sequestration reached up to 1.8–9.4 and 7.5–17.3 Mg ha^?1 at the 0–15 cm layer over a 7- and 32-year rehabilitation period compared to the control site, suggesting that desertification control has a great potential for sequestering soil C and improving soil quality in northwest China.