Condition and trends of ecosystem services and biodiversity
Pereira, Henrique M., Reyers, Belinda, Watanabe, Masataka, Bohensky, Erin, Foale, Simon, Palm, Cheryl, Espaldon, Maria Victoria, Armenteras, Dolors, Tapia, Maricel, Rincon, Alexander, Lee, Marcus J., Patwardhan, Ankur, and Gomes, Ines (2005) Condition and trends of ecosystem services and biodiversity. In: Ecosystems and Human Well-Being: multiscale assessments. Millennium Ecosystem Assessment Series, 4 . Island Press, Washington, USA, pp. 171-203.
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The sub-global assessments show that several ecosystem services are in fair to poor condition and declining. Despite some gains in the provisioning of food, water, and wood, the capacity of ecosystems to continue to provide these services is at risk in several locations; problems with provisioning services include deterioration of water quality, deterioration of agricultural soils, and incapacity of supply to meet demand. Some threats affecting regulating services are loss of forest cover, rangeland degradation by overgrazing (particularly in drylands), loss of wetlands to urban development and agriculture, and change in fire frequency. Problems with cultural services include loss of cultural identity and negative impacts from tourism. Biodiversity is decreasing due to the loss of habitats and the reduction of species population sizes. Species declining particularly fast include species with large body size, species occupying high trophic levels, and species that are harvested by humans.
In general, the assessments found the condition of water provisioning and biodiversity at global and sub-global scales to be congruent. However, in some cases, the sub-global assessments reported a poorer or better condition than the global findings for that region. Differences were due to the effects of drivers that were not picked up at the global scale, or to fine-scale heterogeneities missed in coarser-scale analyses at the global scale. There were more mismatches for biodiversity than for water provisioning because the concepts and measures of biodiversity were more diverse in the sub-global assessments.
Land use change is the most important driver for provisioning, supporting, and regulating services and for biodiversity. Some direct drivers of ecosystem change were also indicators of the condition of the service (for example, harvest pressure is an indicator of biodiversity). Indirect drivers control the patterns of demand for provisioning and cultural services, thus inducing changes in ecosystems. Tourism was found to have a negative impact on biodiversity in the Northern Range, SAfMA, Portugal, and Caribbean Sea assessments. While human controlled drivers play a major role in determining the condition of ecosystem services, local biophysical constraints such as climate and soils also limit the production of ecosystem services.
Clear trade-offs exist among ecosystem services. For example, a potential trade-off situation exists at one site in the southeastern part of the Gariep Basin, where biodiversity is totally irreplaceable and protein and caloric production are highly irreplaceable. The sub-global assessments, like the MA global assessment, found that an increase in provisioning services generally occurs at the expense of regulating services, supporting services, and biodiversity, or at the expense of the capacity of ecosystems to provide services to future generations. Trade-offs also occur among provisioning services such as between irrigated agriculture and freshwater provisioning.
Trade-offs among ecosystem services can be minimized. The studies of the Tropical Forest Margin assessment in Indonesia and Cameroon showed that a ‘‘middle path’’ of development involving smallholder agroforestry and community forest management for timber and other products is feasible. Such a path could deliver an attractive balance between environmental benefits and equitable economic growth.
New approaches were developed to demonstrate, communicate, and discuss these trade-offs with policy-makers. One was the Alternative to Slashand- Burn matrix, where natural forest and alternate land use systems were scored against criteria reflecting the objectives of different interest groups in the Tropical Forest Margins assessment. Another was the use of a decision support tool, the Podium Model, to assess options for cereal-based food security and water availability in the Gariep Basin of southern Africa; this showed that expanding irrigated area alone, at large costs to water provisioning services, is unlikely to improve food security.
The sub-global assessments improved understanding of how human well-being depends on ecosystems, in several ways. Examples include inventories of ecosystem services (for example, 64 plant species used to extract biochemical substances were identified in Downstream Mekong); calculations of trade-offs among services (for example, between water conservation and food production in SAfMA); economic valuations of ecosystem services such as tourism, soil protection, run-off regulation, and carbon sequestration (Portugal), and lessons about the importance of cultural landscapes and biodiversity for local livelihoods (Bajo Chirripo´ and India Local).
The sub-global assessments used numerous and varied methods to assess the current condition and trends in ecosystem services. These methods included geographic information systems, remote sensing, inventories, indicators, economic valuation, and participatory approaches. Participatory approaches were useful in incorporating both scientific and local knowledge into the assessments. Because the sub-global assessments used different definitions and methods of assessing condition, the findings were not always comparable across assessments.
The different approaches used to assess the condition of ecosystem services reflected different interpretations of what is meant by the condition of an ecosystem service. Some assessments emphasized the ecological capacity of the system to provide the service (for example, Portugal) while other assessments emphasized the production and the demand for the service (for example, SAfMA) or equity of access to the service (for example, Sinai). Differing emphases were partially related to the socioeconomic development of the region being assessed: issues of equity and production versus demand were not the main focus of industrial-country assessments (Portugal, Sweden, Norway).
Several sub-global assessments applied novel approaches to the assessment of biodiversity. These include measures such as the Biodiversity Intactness Index (SAfMA), the Reef Condition Index (PNG), and the Ecological Integrity Index (Coastal BC). Each of these measures integrated indicators of different aspects of biodiversity condition into a single index, that could then be used to enhance the dialog on biodiversity with policy-makers and the public.
There is a need for long-term monitoring of the condition of all types of ecosystem services using comparable indicators. Limited data were available to assess the condition of regulating and supporting services. There is an overwhelming lack of historical data on the state of biodiversity in the sub global assessments. In many locations, sub-global assessments collected data on the condition of ecosystem services for the first time; these data can serve as a baseline for future assessments. The lack of data and the spatial heterogeneity of the condition of ecosystem services led to uncertainty in the assessment of condition and trends of ecosystem services. The development of fine tuned responses to the deteriorating conditions of ecosystem services will require a concerted effort at data collection and analysis at all scales.
|Item Type:||Book Chapter (Research - B1)|
|Keywords:||ecosystem services; water quality; agricultural soils; biodiversity; ecological capacity; socioeconomic development|
|FoR Codes:||05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050202 Conservation and Biodiversity @ 0%|
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050209 Natural Resource Management @ 0%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050211 Wildlife and Habitat Management @ 0%
|Deposited On:||02 Jun 2007|
|Last Modified:||13 Feb 2011 22:32|
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