Functional Groups and Functional Types

This lecture shifts from traits to functional groups and functional types, focusing on how species are categorized based on shared biological characteristics.
The act of grouping simplifies the world, reducing cognitive load.
Functional groups are used irrespective of their perfect correspondence to nature, serving as simplifications for scientific and management purposes.
Their usefulness, robustness, and reliability should be examined, especially when used for science or management.

Functional groups address the species problem by reducing the number of entities to study and allowing transfer of results across species or conditions.
They are particularly useful in monitoring and predicting changes in biological systems.

Functional groups are context-specific, meaning their utility depends on the issues of concern, the focal question, and the scales at which one is working.

Context: Managing vegetation for sustained grazing in Australian rangelands on a 1 to 10 year time scale.
Concerns: Stock turnover, mortality, reproduction rates, vegetation condition, and classification as native vegetation remnant.
Functional Groups/Attributes Used:
- Palatability to livestock (palatable vs. unpalatable).
- Growth form (grasses, forbs/herbs, woody weeds/shrubs).
- Response to grazing (increasers vs. decreasers).
- Cool vs. warm season growers.
- Annual vs. perennial life cycles.
- Noxious weeds.

Context: Conserving biodiversity in a region over a longer timeframe.
Concerns: Fire hazard, remnant vegetation, biodiversity support, and salinity.
Functional Groups/Attributes Used:
- Woody vs. non-woody vegetation.
- Effect on fuel accumulation (fire risk).
- Rooting depth (for salinity management).
- Invasiveness.
- Rare or threatened status.
- Fire and grazing responses.
- Resources provided for other biodiversity (e.g., nectar).

Context: Modeling climate change impacts on a continental or regional scale, with a time horizon of decades to centuries.
Concerns: Biomass and carbon sequestration.
Functional Groups/Attributes Used:
- Woody vs. non-woody vegetation.
- Disturbance response (fire response).
- Evergreen vs. deciduous.
- Carbon metabolism (C3 vs. C4).
  - $C4$ species perform better in warmer conditions due to more efficient water use.

Ecological Function: How species influence the ecosystem.
Response: How species respond to disturbance or environmental gradients.
Resource Use: How species use resources, especially common in invertebrate classifications.
Emphasis is process-oriented, focusing on ecological processes.

Generalizing from particular cases to a general principle through observation and natural history knowledge.
Can be objective or subjective.
Example: Plant growth form (grasses, forbs, shrubs, trees).
Conceptual dimensions include pioneer vs. late successional species and gap-demanding vs. shade-tolerant species.

Megan Stavie Devier and Bob Stenick's scheme classifies algae by comparative anatomy (size of thallus, morphology).
Categories include single cells, fronds, sheets, corticoid forms, radial forms, and calcified forms.

The biomass of functional group i is a function of its rate of recruitment plus its production, net primary production (the amount of biomass produced per unit biomass, per unit area, per unit time), and minus some disturbance losses.
$Biomass_{i} = Recruitment + Production - Disturbance Loss$
Mass-specific productivity: the amount of carbon grown from per unit of biomass per unit time.

Using multivariate statistics (cluster analysis) on large datasets of species traits (vegetative growth form, leaf type, fire responses, growth timing, life history, seed biology).
Example: Michelle Leishman's cluster analysis for rangeland species.

Starting with a general principle and logically deducing specific cases.
Begins with a particular process or property and evaluates logical possibilities.

Considering fire effects on mature plants (re-sprout or fire-killed) and seeds (die or persist).
Using a contingency table to derive four functional groups based on logical combinations of plant and seed survival.
- Plants die, seeds die.
- Plants survive, seeds survive.
- Plants survive, seeds die.
- Plants die, seeds survive.

Peter Clark's work on habitat islands associated with rocky areas, which experience less frequent fires.
Comparing abundance of re-sprouters and fire-killed plants in surrounding forests vs. rocky outcrops.
Selection for different functional groups based on fire response in different environments.

Evaluating the binary classification of resprouting by examining species responses to clipping and burning treatments.
Experiment with 45 species in Central West New South Wales, testing control, clipping, and clipping + burning treatments.
Results show a range of behaviors, indicating that species exhibit a spectrum of responses, not just binary (resprouter vs. non-resprouter).
Building a statistical model to account for sampling variation.

Weak and strong resprouters that explains around 60% of the deviance (like variance).
It is not zero and $100 \%$ , but weak and strong, Roose Routes

Growth forms can indicate resprouting ability. Grasses may be good resprouters but not all of them. Woody species can be extremely varied.
Forbes and Caesalpinioideae are very good indicators of their re sprouting response.

The vital attributes scheme is used for replacement sequences, to logically conclude the possible progressions of vegetation after a series of disturbances.
It can predict the landscape-wide mix of species in response to disturbance regime.
- Vital Attribute 1: How a species copes with disturbance on a juvenile, mature, seed only, and absent level. This includes plants and their dispersing seeds, plants that recover from a seed bank, sprouting juveniles etc.
Vital Attribute 2: Can the species establish in the face of established vegetation, or are they intolerant of them, or they require established vegetation?
If you combine those bits of information for a particular species, for example; An acacia has a long lived seed pool and it is intolerant of competition then it has a method that can tell you how it will perform under recurrent fires.
Used with Time Scales the model can be used to estimate vegetation change over time.