Habitat definition| Biodiversity A-Z (original) (raw)

Contents

  1. Notes on definition
  2. Further definitions
  3. Key points
  4. Introduction
  5. History
  6. Importance of habitats in species survival
  7. Multilateral Environmental Agreement
  8. Standards
  9. Measuring habitat: Use of habitat maps
  10. Methods in mapping habitat

Notes on definition

There are numerous scientific definitions of habitat 2 and two definitions which come from Multilateral Environmental Agreements (MEA). In addition, the term has been used in many environmental safeguard standards, the most high profile of which is the International Finance Corporation’s (IFC) Performance Standard 6 (PS6). Generic definitions, including that of the Convention on Biological Diversity (CBD) and Convention on Migratory Species (CMS) define habitat broadly as an area providing suitable conditions for the survival of a particular species or organism. Whilst the CMS definition focuses on species, the CBD definition allows for the presence of populations or organisms to delineate habitats and also specifies the necessity for natural occurrence in the definition. CMS links the definition to the convention’s context of conserving migratory species. Scientific definitions broadly define habitat as, “as the suite of resources (food, shelter) and environmental conditions (abiotic and biotic) that determine the presence, survival and reproduction of a population” 3. The main feature of the scientific definition is that it describes the environmental characteristics in more detail and highlights that the conditions ‘determine’ the presence of a species.

Further definitions

Supplementary definition

Habitat means any area in the range of a (…) species which contains suitable living conditions for that species.

Convention on Migratory Species (CMS) Article 1 Interpretation, Paragraph 3 (g)

Supplementary definition with particular business relevance

A terrestrial, freshwater, or marine geographical unit or airway that supports assemblages of living organisms and their interactions with the non-living environment.

International Finance Corporation PS6 (2012)

Key points

Introduction

The habitat of an organism provides the requirements for that species to survive. The early concept of habitat arose because naturalists started to question why some species were present in one location but not in another 4. The paradigm of habitat is now firmly embedded as one of the key concepts of nature and is therefore often the focus of conservation.

History

The history of the habitat concept goes back to work carried out in the early 20th century when a variety of naturalists examined the zoning of species and linked it to environmental conditions 4. Habitat depends on both the abiotic (non-living) features of the environment such as the underlying geology and climatic patterns, and the biotic features such as the presence of particular species 5. Species are only adapted to live in certain habitat types 6.

Importance of habitats in species survival

Species are dependent on their habitat for their survival. Habitat loss and fragmentation has been identified as one of the primary causes of species range decline, numerical abundance decline, and extinction 7. There is also some research which indicates that habitat loss may cause the selective extinction of key species which are important for ecosystem function 8.

Multilateral Environmental Agreement

Due to the importance of habitat in supporting species, habitat protection is one of the focuses of conservation effort and legislation globally. Habitat is defined within the Convention on Biological Diversity (CBD) and is particularly relevant to Article 8 (d). This Article relates to in-situ conservation and is concerned with the protection of natural habitats and the maintenance of viable populations of species in their natural surroundings. Habitat is central to the concept of in-situ conservation, where the aim is to conserve natural habitats supporting the preservation of the ecological processes which underpin ecosystem function. Targets within the CBD Strategic Plan for Biodiversity 2011-2020 highlight the protection of habitat and reduction in its rate of loss as key elements. Habitat loss is the focus of the associated Aichi Target 5 which aims to at least halve the rate of habitat loss 9. Protected area increases are part of another Aichi target, Target 11, which aims to increase the percentage of habitat protected and also particularly highlights the fact that this increase should ensure that the protected area coverage should be ecologically representative. Therefore the protected area network should encompass a representative range of habitats. The Convention on Migratory Species (CMS) also defines habitat in order to support the functions of the convention in the protection of migratory species. Migratory species are particularly interesting because they often utilise only a portion of their range at any one time - meaning they often occur in numerous different habitats - or they link the same type of habitat through time and over potentially large distances. The CMS describe migratory species as ‘living threads’ linking habitats in different locations over time 10.

Standards

Habitat is a key element in defining or demonstrating biodiversity value in many financial standards, which often contain a specific definition of habitat. This definition is tailored to the standard and its application. For example, the International Finance Corporation Performance Standard 6 (IFC PS6) uses the concepts of natural, modified and critical habitat to structure mitigation approaches to potential impacts on biodiversity. IFC depart from the more traditional definition for habitat because projects must account for other ecological aspects, in addition to species, when deciding if they are overlapping with ‘critical’ or ‘modified’ habitat as defined by the standards.

Measuring habitat: Use of habitat maps

Measuring habitat is necessary to identify conservation priorities and facilitate better management. Mapping of habitats can be used to assist decision makers in numerous ways including, identification of priority areas; policy implementation 11; to meet legislation stipulations 12 or international targets, such as the Aichi Targets 13. Habitat mapping is important within spatial planning particularly in the application of ecosystem-based management and the designation of marine protected areas 14 15. Defining an appropriate scale at which to map or categorise habitat is difficult because of the variety of species and habitat niches present in the environment. For example the range of a large predator will encompass a variety of different habitat types while the habitat of a particular parasite will often be limited to a single host species 4. There is broad consensus on the definition of wider habitat types such as forest or grassland but the finer scale definitions are more complicated. There is no global consensus on a comprehensive list of habitat types. However, there are a number of habitat classification systems using defined hierarchies 16, 17. IUCN has developed a habitat classification scheme featuring both terrestrial and marine habitat types divided into three hierarchical levels which are used to describe the habitat types in which species on the IUCN Red List occur 18.

Methods in mapping habitat

  1. TERRESTRIAL MAPPING

Habitat mapping in a terrestrial environment usually involves recording features such as vegetation type across areas of land 19. At a local scale habitat mapping can be conducted by walkover surveys 20. However, it is not possible or practical to carry out large scale mapping with this level of effort. At regional or global scale land cover is often used as a proxy for habitat mapping 21. Land cover is often mapped using aerial and satellite images. Land cover is the visible features of the Earth surface including the vegetation layer as well as natural (e.g. rivers) and manmade (e.g. cities and roads) features 22, 23. These features reflect solar radiation in different ways and therefore demonstrate unique spectral characteristics which can be mapped using satellites.

2. MARINE MAPPING

Mapping the marine environment is more challenging because water surfaces demonstrate more complex reflective properties when compared to terrestrial surfaces. Satellite sensors are therefore designed differently for use in the marine environment 22. Only a small fraction (5-10%) of the seafloor has been surveyed, to identify bathymetry (underwater depth information), with an equivalent resolution to similar terrestrial studies 24, 25. It is possible to measure biological characteristics in the marine environment, and some physical characteristics, such as sea surface temperature, by satellite 22, 26. However, there still remains considerable challenges to improve marine habitat mapping 26, 27.

References & Websites

  1. JNCC (2013) UK Habitat Classification.
  2. Convention on Biological Diversity (1992) Convention on Biological Diversity. Secretariat of the Convention on Biological Diversity, Montreal, Canada
  3. Hall L, Krausman P, Morrison M (1997) The habitat concept and a plea for standard terminology. Wildl Soc Bull 25:173–182
  4. Gaillard J-M, Hebblewhite M, Loison A, Fuller M, Powell R, Basille M, Van Moorter B (2010) Habitat-performance relationships: finding the right metric at a given spatial scale. Philos Trans R Soc Lond B Biol Sci 365:2255–65
  5. Petren K (2001) Habitat and niche, concept of. In: Levin SA (ed) Encycl. Biodivers. Vol 3. Academic Press, San Diego, USA, pp 303–316
  6. Ellison AM, Bank MS, Clinton BD, et al (2005) Loss of foundation species: consequences for the structure and dynamics of forested ecosystems. Front Ecol Environ 3:479–486
  7. Soberon J, Pearson RG, Martinez-Meyer E (2011) Ecological Niches and Geographic Distributions (MPB-49). Princeton University Press, Princeton, USA
  8. Pimm SL, Raven P (2000) Biodiversity. Extinction by numbers. Nature 403:843–5
  9. Tilman D, May RM, Lehman CL, Nowak MA (1994) Habitat destruction and the extinction debt. Nature 371:65–66
  10. CBD Secretariat (2010) The Strategic Plan for Biodiversity 2011-2020 and the Aichi Biodiversity Targets. Document UNEP/CBD/COP/DEC/X/2. Secretariat of the Convention on Biological Diversity, Nagoya, Japan
  11. CMS Secretariat (2011) Updated Strategic Plan. Document 2006-2014.UNEP/CMS/Conf. 10.22/Rev.1. Secretariat of the Convention on Migratory Species, Bergen, Norway
  12. Maes J, Teller A, Erhard M, et al (2013) Mapping and Assessment of Ecosystems and their Services. An analytical framework for ecosystem assessments under action 5 of the EU biodiversity strategy to 2020. Publications office of the European Union, Luxemburg, Belgium
  13. European Union (1992) Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora. OJ L 206/7
  14. European Comission (2011) Our life insurance, our natural capital: an EU biodiversity strategy to 2020. COM(2011) 244 final. European Commission, Brussels, Belgium
  15. Cogan CB, Todd BJ, Lawton P, Noji TT (2009) The role of marine habitat mapping in ecosystem-based management. ICES J Mar Sci 66:2033–2042
  16. Jordan A, Lawler M, Halley V, Barrett N (2005) Seabed habitat mapping in the Kent Group of islands and its role in Marine protected area planning. Aquat Conserv Mar Freshw Ecosyst 15:51–70
  17. Mapping European Seabed Habitats (2007) EUNIS classification. http://www.searchmesh.net/default.aspx?page=1807. Accessed 2 Aug 2013
  18. Commission of the European Communities (1991) CORINE biotopes. Commission of the European Communities, Brussels, Luxembourg
  19. IUCN (2007) IUCN Habitats Classification Scheme IUCN. International Union for the Conservation of Nature, Gland, Switzerland
  20. Environment Agency (2003) River Habitat Survey in Britain and Ireland Field Survey Guidance Manual. UK Environment Agency, London, UK
  21. ESA (2011) Gorilla Natural Habitat Monitoring Service. http://due.esrin.esa.int/prjs/prjs55.php. Accessed 2 Aug 2013
  22. Campbell JB (2006) Introduction to Remote Sensing. Taylor & Francis Group, London, UK
  23. Di Gregorio A, Jansen LJM (2000) Land Cover Classification System. Food and Agriculture Organisation, Rome, Italy
  24. Wright D, Heyman W (2008) Introduction to the special issue: marine and coastal GIS for geomorphology, habitat mapping, and marine reserves. Mar Geod 31:223– 230
  25. Sandwell DT, Smith WHF, Gille S, Kappel E, Jayne S, Coakley B, Géli L (2006) Bathymetry from Space Rationale and requirements for a new , high- resolution altimetric mission. Comptes Rendus Geosci 338:1049–1062
  26. Foster-smith B, Connor D, Davies J (2007) What is habitat mapping. MESH Guid. to Habitat Mapp.
  27. Ross RE, Howell KL (2013) Use of predictive habitat modelling to assess the distribution and extent of the current protection of “listed” deep-sea habitats. Divers Distrib 19:433–445

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