Functional trait diversity

Data gathered during Species diversity surveys can be linked to functional traits.

Common approaches for classifying functional traits include:

• Plant traits: max height, habitat, flowering start, flowering duration, pollen vector (wind vs animal), seed dispersal agent (wind vs animal), seed weight, CSR (competitor, stress tolerant, ruderal) strategy, leaf persistence, life history, life form, sprout insulation, lateral spread, reproductive strategy, woodiness, light indication (Ellenberg values – shade vs light preference on a scale of 1-9)
• Animal traits: body size, life form, trophic level, dispersal ability, habitat requirement, habitat specificity, temperature needs
• Aboveground insects: trophic level, diet breadth, dispersal ability, voltinism (number of broods per year), body size
• Birds: body size, trophic guild (granivore, insectivore, carnivore), dispersal ability, feeding strategy, nesting strategy, migration behaviour, dietary specialisation
• Fungi: fruit body size, fruit body type, fruit volume, fruit thickness, tree host preference, dispersal vector (asexual spores, mycelial cores)
• See Lelli et al. 2019, Moretti and Legg 2009 and Vandewalle et al. 2010 for more info

Plant functional traits can be linked to ecosystem services. For examples, a study looking at functional traits in grassland ecosystems in Sweden assessed the following traits (Walden et al. 2023):

• Livestock production: leaf dry mass, specific leaf area, foraging value
• Pollination: pollination syndrome (insect pollinated or not), flowering duration, nectar quantity, pollen quantity
• Temperature regulation: height, specific leaf area, root architecture type (tap root, adventitious, fibrous), lifespan (longer-lived plants better for temp. reg.)
• Water retention: specific leaf area, height, clonal lateral spread rate (non-clonal, <0.01 m/year, 0.01-0.25 m/year, >0.25 m/year), root architecture type
• Cultural heritage: grassland specialist, mentions in traditional music
• See Walden et al. 2023 for more info

Multiple online resources define functional traits for different species groups:

• The Biological Records Centre website summarises relevant trait datasets for UK plants, invertebrates, birds and mammal
• Ecological Flora of Britain and Ireland
• Ellenberg’s indicator values for British plants  (indicator values of plant tolerance to light, moisture, pH, nitrogen, salt)
• TRY Global Plant Trait Database
• Morphological trait database of European saproxylic beetles
• Traits data for butterflies and macro-moths of Great Britain and Ireland
• Sources of carabid beetle trait data

The fundiversity package can aid calculation of functional diversity indices in R (Grenié and Gruson 2023). Commonly used metrics include:

• Mean trait value per community (average of trait values for a community, weighted by relative abundance) – dominant species have a disproportionate effect on ecosystem function (Roscher et al. 2022)
• Rao’s quadratic diversity (functional trait diversity)