Soil invertebrates are represented by a variety of animals which may represent as much as a quarter of all currently described biodiversity (DecaŽns et al. 2006). They are highly implied in soil behavior. As a consequence, studying the interactions between soil invertebrates and their environment are of great interest. Functional trait-based approaches have notably revealed new insights in the comprehension of soil invertebrate assemblages. It concerns characteristics of individuals that affect their fitness and govern their responses to their surrounding environment. Traits refer to the definition proposed by Pey et al. for soil invertebrate inspired from those of Violle et al. "any morphological, physiological, phenological or behavioural feature measurable at the individual level, from the cell to the whole-organism level, without reference to any other level of organization". Ecological preferences result from the optimum and/or the breadth of distribution of a trait along an environmental gradient (e.g. moistures preferences) (Pey et al. in revision; Violle et al. 2007)
Currently, some major drawbacks still impair the development of these approaches for soil invertebrates (isolated initiatives, heterogeneous data, lack of semantics). Hence, building a thesaurus of soil invertebrate trait is one of a way to facilitate trait data integration and navigation among multiple data sources and data integrity.
How the T-SITA works?
The T-SITA proposes a non-exhaustive, semantically structured, list of traits and ecological preferences.
Terms are organized into a conceptual hierarchical tree with their fathers and sons ("Browse hierarchy" tab). Each term is conceptually included into its father term. For instance, the "Reproduction type" trait term was included in the father term "Physiology". It means that the concept linked to the "Reproduction type" term is included into the concept linked to the "Physiology" term. "Reproduction type" has two son terms: "Asexual reproduction" and "Sexual reproduction". It means that the concepts linked to the "Asexual reproduction" and "Sexual reproduction" terms are included into the concept linked to the "Reproduction type" term.
Each term is typified by a unit. Traits and ecological preferences terms are identified by having either a numerical unit or being "categorical". Quantitative traits/ecological preferences are informed by numerical values and have therefore a numerical unit. For instance, the unit of the "body length" trait term is mm. Otherwise, qualitative traits/ecological preferences are informed by textual data. To be usable, they need to be categorized into attributes, e.g. by fuzzy coding procedures (Chevenet et al. 1994). As a consequence, their unit is specified as being "categorical". For instance, the unit of the "habitat" preference term is "categorical". "Habitat" is categorized into several attributes, such as "Agricultural area" or "Wetland" terms. Such attributes appear as son terms of the habitat preference in the thesaurus hierarchy. Attributes are identified in the thesaurus by having a unit specified as being an attribute. For instance, the unit of "Wetland" term is "attribute". In addition, a categorical trait or ecological preference can have multi-levels sons. For instance, the habitat preference is the father of "Agricultural area" which is itself the father of "Arable land", "Fallow" and "Perennial crop". It was done to take into account the heterogeneous accuracy of the textual literature informing the categorical traits or preferences.
How to use it?
To request T-SITA content, two types of searches are proposed. First, a navigation tree with an auto-completed field search can be used ("Browse hierarchy" tab). Once the term of interest is located, click on it to have access on its properties (e.g. definition, unit). Second, a "Faceted search" tab has also been developed to select terms according to their common properties. At the moment in the T-SITA, terms can be filtered according to several facets which gather terms either by their expression basis, the organ concerned, the main biological function concerned, their nature by distinguishing the traits from ecological preferences and finally by the environmental aspect concerned. Select one or several proposed properties (when selected they are colored in green) of the different facets. A list of terms appears in a below result part according to your selection. To have access on properties of a term, click on it in the result part.
The T-SITA is linked with a fully operational database on soil invertebrate traits ("BETSI database" tab). In the Web page describing the trait/ecological preference information, statistics coming from the BETSI database for the concerned term were displayed. It displays for each of them, the input number of raw data observations in the database and how many species it concerns.
Chevenet, F., S. Dolťdec and D. Chessel (1994). "A fuzzy coding approach for the analysis of long-term ecological data." Freshwater Biology 31: 295-309.
DecaŽns, T., J. J. Jimenez, C. Gioia, G. J. Measey and P. Lavelle (2006). The values of soil animals for conservation biology. European Journal of Soil Biology. 42: S23-S38.
Pey, B., J. Nahmani, A. Auclerc, Y. Capowiez, D. Cluzeau, J. Cortet, T. DecaŽns, L. Deharveng, F. Dubs, S. Joimel, C. Briard, F. Grumiaux, M.-A. Laporte, A. Pasquet, C. Pelosi, C. Pernin, J.-F. Ponge, S. Salmon, L. Santorufo and M. Hedde (in revision). "Current use of and future needs for soil invertebrate functional traits in community ecology." Basic and Applied Ecology.
Violle, C., M. L. Navas, D. Vile, E. Kazakou, C. Fortunel, I. Hummel and E. Garnier (2007). "Let the concept of trait be functional!" Oikos 116(5): 882-892.