3. Ecosystem Functions
Ecosystem function is the capacity of natural processes and components to provide goods and services that satisfy human needs, either directly or indirectly (de Groot et al 2002). By following this definition, ecosystem functions are conceived as a subset of ecological processes and ecosystem structures. Each function is the result of the natural processes of the total ecological sub-system of which it is a part. Natural processes, in turn, are the result of complex interactions between biotic (living organisms) and abiotic (chemical and physical) components of ecosystems through the universal driving forces of matter and energy.
There are four primary groups of ecosystem functions
(1) regulatory functions, (2) habitat functions, (3) production functions and (4) information functions. This grouping concerns all ecosystems, not only for forests, but it is interesting how well it fits into forest ecosystem functions (de Groot et al. 2002).
General characterisation of ecosystem functions are: (for more detail see Table F1)
(1) Regulatory functions: this group of functions relates to the capacity of natural and semi-natural ecosystems to regulate essential ecological processes and life support systems through bio-geochemical cycles and other biospheric processes. In addition to maintaining the ecosystem (and biosphere health), these regulatory functions provide many services that have direct and indirect benefits to humans (i.e., clean air, water and soil, and biological control services).
(2) Habitat functions: natural ecosystems provide refuge and a reproduction habitat to wild plants and animals and thereby contribute to the (in situ) conservation of biological and genetic diversity and the evolutionary process.
(3) Production functions: Photosynthesis and nutrient uptake by autotrophs converts energy, carbon dioxide, water and nutrients into a wide variety of carbohydrate structures which are then used by secondary producers to create an even larger variety of living biomass. This broad diversity in carbohydrate structures provides many ecosystem goods for human consumption, ranging from food and raw materials to energy resources and genetic material.
(4) Information functions: Since most of human evolution took place within the context of an undomesticated habitat, natural ecosystems provide an essential 'reference function' and contribute to the maintenance of human health by providing opportunities for reflection, spiritual enrichment, cognitive development, recreation and aesthetic experience.
The ecosystem function approach provides a holistic view of forest based goods and services, and by paying more attention to ecosystem-based services this closely relates to the characteristics of forest ecosystems.
If a schematic approach presented by the FAO NWFP programme is amended to three major categories of ecosystem functions (de Groot et al (2002), one gets a grouping of forest products and services as illustrated in (Figure F6 – LINK TO FIGURE F6). The information function is renamed to recreational and cultural services for simplicity. The production function is represented by the wood and non-wood goods classifications as introduced above.
The general characterisation of the ecosystem functions are shown in Table F1.
Table F1: Classification of ecosystem functions, goods and services (according to de Groot et al. 2002)
|2.1. Regulation functions and related ecosystem services
||2.1.1. Gas regulation
2.1.2. Climate regulation
2.1.3. Disturbance prevention
2.1.4. Water regulation
2.1.5. Water supply
2.1.6. Soil retention
2.1.7. Soil formation
2.1.8. Nutrient cycling
2.1.9. Waste treatment
2.1.11. Biological control
|2.2. Habitat functions and related ecosystem services
||2.2.1. Refugium function
2.2.2. Nursery function
|2.3. Production functions and related ecosystem goods and services
2.3.2. Raw materials
2.3.3. Genetic resources
2.3.4. Medicinal resources
2.3.5. Ornamental resources
|2.4. Information functions and related ecosystem goods and services
||2.4.1. Aesthetic information
2.4.2. Recreation and (eco)tourism
2.4.3. Cultural and artistic inspiration
2.4.4. Spiritual and historic information
2.4.5. Scientific and educational information