|
Ecosystem Functional Type (EFT) (Fig.1)〔 is a new ecological concept to characterize ecosystem functioning. Ecosystem Functional Types 〔〔 are defined as groups of ecosystems or patches of the land surface that share similar dynamics of matter and energy exchanges between the biota and the physical environment. The EFT concept is analogous to the Plant Functional Types (PFTs) concept, but defined at a higher level of the biological organization. As plant species can be grouped according to common functional characteristics, ecosystems can be grouped according to their common functional behavior. One of the most used approaches to implement this concept has been the identification of EFTs from the satellite-derived dynamics of primary production,〔〔 an essential and integrative descriptor of ecosystem functioning. == History == In 1992, Soriano and Paruelo proposed the concept of Biozones to identify vegetation units that share ecosystem functional characteristics using time-series of satellite images of spectral vegetation indices. Biozones were later renamed to EFTs by Paruelo et al. (2001),〔 using an equivalent definition and methodology. Shugart (1997) was one of the first authors that used the term EFT as “aggregated components of ecosystems whose interactions with one another and with the environment produce differences in patterns of ecosystem structure and dynamics”. Walker (1997) proposed the use of a similar term, vegetation functional types, for groups of PFTs in sets that constitute the different states of vegetation succession in non-equilibrium ecosystems. The same term was applied by Scholes et al. (1997) in a wider sense for those areas having similar ecological attributes, such as PFTs composition, structure, phenology, biomass or productivity. Several studies have applied hierarchy and patch dynamic theories for the definition of ecosystem and landscape functional types at different spatial scales, by scaling-up emergent structural and functional properties from patches to regions. Valentini et al. (1999) defined land functional units by focusing on patches of the land surface that are able to exchange mass and energy with the atmosphere and show a coordinated and specific response to environmental factors. Paruelo et al. (2001) 〔 and Alcaraz-Segura et al. (2006, 2013) 〔 refined the EFT concept and proposed a remote-sensing based methodology to derive them. Since then, several authors have implemented the idea under the same or similar approaches using NOAA-AVHRR, MODIS and Landsat archives.〔〔 In brief, all these approaches use the seasonal dynamics of spectral indices related to key functional aspects of ecosystems such as primary production, water exchange, heat exchange and radiative balance. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ecosystem Functional Type」の詳細全文を読む スポンサード リンク
|