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Abstract:
Questions: Heinz Ellenberg classically defined “indicator” scores for species representing
their typical positions along gradients of key environmental variables,
and these have proven very useful for designating ecological distributions. We
tested a key tenent of trait-based ecology, i.e. the ability to predict ecological
preferences fromspecies’ traits. More specifically, can we predict Ellenberg indicator
scores for soil nutrients, soil moisture and irradiance from four well-studied
traits: leaf area, leaf dry matter content, specific leaf area (SLA) and seed
mass? Can we use such relationships to estimate Ellenberg scores for species
never classified by Ellenberg?
Location: Global.
Methods: Cumulative link models were developed to predict Ellenberg nutrients,
irradiance and moisture values from Ln-transformed trait values using
922, 981 and 988 species, respectively.We then independently tested these prediction
equations using the trait values of 423 and 421 new species that occurred
elsewere in Europe, North America and Morocco, and whose habitat affinities
we could classify from independent sources as three-level ordinal ranks related
to soilmoisture and irradiance. The traits were SLA, leaf dry matter content, leaf
area and seedmass.
Results: The four functional traits predicted the Ellenberg indicator scores of site
fertility, light and moisture with average error rates of <2 Ellenberg ranks out of
nine. We then used the trait values of 423 and 421 species, respectively, that
occurred (mostly) outside of Germany butwhose habitat affinities we could classify
as three-level ordinal ranks related to soil moisture and irradiance. The predicted
positions of the new species, given the equations derived from the
Ellenberg indices, agreed well with their independent habitat classifications,
although our equation for Ellenberg irrandiance levels performed poorly on the
lower ranks.
Conclusions: These prediction equations, and their eventual extensions, could
be used to provide approximate descriptions of habitat affinities of large numbers
of speciesworldwide.
