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The Traitbase Data Structure
The Traitbase has several levels of information.
RAW Data Level
The basic level entails the raw data - each record gives a trait
value for a certain species and the source of information. Depending
on the origion of the data, this source can be literature or
databases of the LEDA partners. In this case you will find the
appropriate literature reference.
Newly measured data are referenced according to the fieldsite,
including georeference information and habitat characteristics.
Please refer to the General Standards in the LEDA Data Standards for an
extensive description of the structure of these data. Whenever
literature sources allowed to extract habitat information or
georeference these data were also incorporated in the Traitbase.
The LEDA Traitbase often shows several records for a given species
and trait, depending on the sources that were available. The values
or categories need not to be consistent. Depending on habitat and
trait plasticity, different researchers may have observed different
expressions of a trait for a species. At the raw data level, the
Traitbase offers to retrieve the variability of trait expression for
single species or species sets in response to habitat or
geographical information. You can retrieve raw data with the help of
the web query.
Aggregated Data Level
The aggregated level gives aggregated trait values per species.
Depending upon the trait considered, several types of aggregated
values are available. Examples are: relative frequency of
categories, absolute frequency of categories, modal categories,
index functions, maximum values, minimum values, average values,
standard deviation and median values.
Aggregation may either be carried out on the original values stored
in the database or on derived values. For instance, if the average
canopy height of a species is to be calculated both from records
containing a maximum observed value and a minimum observed value and
from records containing a single observed value, a single value is
calculated on a per-record basis from minimum and maximum values for
the former records. The resulting calculated single values are then
aggregated together with the single values present in the database.
Owing to the different sources of stored data, the Traitbase
contains data of variable statistical and ecological quality. For
aggregation purposes, each value taken into account for aggregation
is equally weighted, no matter if it is a single value resulting
from online data input or a pre-aggregated value.
Before retrieving aggregated data please make yourself familiar with
the aggregation used for the trait you are interested in. In case of
any doubt, use the raw data level. Aggregation procedures are
described in here.
Please also refer to the help pages. You can retrieve aggregated
trait values with the help of the species fact sheet or the web
query.
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