Download Allocating taxa to PFTs

Allocating taxa to PFTs
In principle, most species belongs to a single PFT. However, pollen taxa can be assigned
to multiple PFTs because they contain multiple species with different
behaviour/responses.
It is important that the taxa to PFT allocation is done as precisely as possible, to avoid
introducing noise into the biomisation process. In some cases, knowledge about the
behaviour of a taxon is incomplete, so we have to pool information from different
regions/experts as far as possible. The important thing to recognise here is that the classes
of descriptors are meant to describe “obligate behaviour”. For example, if it says “yes”
under evergreen and deciduous, it means that some species in the taxon are evergreen and
some are deciduous. Similarly, but perhaps more problematically, if it says yes under
tropical, temperate and arctic it means that some species in the taxon are obligate tropical,
some obligate temperate and some obligate arctic. It does NOT mean that the taxon is
found across the temperature range from artic to tropical – if this were the case, we would
want to assign it to eurythermic on the assumption that its distribution is influenced by
e.g. moisture rather than temperature.
The terminology that we use for different parts of the description of a PFT is not ideal.
Some of the terms have multiple (or emotive) meanings in the literature. It is important
that we try and stick to the definitions below:
Non-native: we do not use introduced species in the biomisation in part because they may
be growing in “protected” environments and in part because they may impact the
scheme and render it less useful for palaeo-reconstructions. We keep these species
in the dataset for diagnostic purposes (i.e. how abnormal/contaminated is the
sample). We generally define non-natives as species that have been introduced
within the last 200-300 years.
Other categories not used in biomisation: general terms (e.g. unknown), Pre-Quaternary
contaminants (e.g. Cingulatisporites), groups that reflect local or non-climatic
factors (intrazonal groups) such as liverworts, mangroves, groups that reflect
depositional context (e.g. algae, obligate aquatics, rushes), groups that reflect land
use (e.g. cultivated).
Moss: small, soft non-flowering non-seeding plants, commonly growing in clumps or
mats. Wquivalent to Bryophyta minus liverworts and hornworts (see above)
Geophyte: a perennial herbaceous plant with an underground storage organ for reserves
of carbohydrates, nutrients, and/or water. Include species that over-winter as
bulbs, corms, tubers, rhizomes, tuberous roots, and enlarged hypocotyls.
Tuft tree: tree form where leaves emerge from trunk rather than from branches
(e.g.palms)
Tuft treelet: species with leaves emerging from trunk rather than branches, but which
never grows >2-3m high
Fern (and fern allies) (Pteridophyta): seedless plants which disperse by shedding spores
to initiate an alternation of generations. Includes true ferms (Filicopsida)
clubmosses (Lycopsida), horsetails in Sphenopsida/Equisetopsida, and whisk
ferns (Psilopsida).

Tree fern: a fern that grows with a trunk to elevate the fronds above
ground level

Eurythermic fern: fern or fern ally which grows in locally-protected
habitats and for which the distribution is not apparently affected by regional-scale
temperature

Tropical fern: fern or fern ally which is confined to regions which do not
experience frost
Succulent: plants which has mechanisms for storing water in leaves or stem. In the field,
can be identified by fleshy nature of leaves or stem. Succulents yield water when
leaf or stem is broken. Many have CAM photosynthesis.
Sedge: monocot flowering plants in the family Cyperaceae
Grass: monocot green plant in the family Poaceae. Note that functionally grasses include
trees (e.g. bamboo), shrub-like forms (e.g. African bunch grasses) and small forblike forms.
Forb: are herbaceous flowering plants that are not graminoids (grasses, sedges and
rushes).
C3/C4: describes photosynthetic pathway.
Annual: Life cycle completed in a single year.
Perennial: plant over-winters and completes life cycle in more than one year.
Eurythermic: wide temperature range. In practice, we do not generally expect
eurythermic plants to survive arctic temperatures.
Tropical: frost-intolerant, i.e. plants that cannot survive frost and require warm winters.
In practice, this generally means plants that are confined to regions with winter
temperature (MTCO) >15ºC. However, given that the occurrence of frost can be
influenced by local factors such as closeness to water, the overwhelming criteria
has to be that there is no known mechanism for surviving frost.
Temperate: has mechanisms for survival when frost occurs and does not require warm
winters. In practice, this generally means MTCO <15ºC. We do not subdivide this
category when classifying e.g. forbs but subdivide it (into warm-temperate and
cool-temperate) for shrubs/trees.
Warm-temperate: frost-sensitive. In practice, regions where MTCO > 5 ºC
Cool-temperate: frost-tolerant and may require chilling for bud-burst to take place. In
practice, regions where MTCO is between 0-5 ºC
Boreal: have mechanisms to tolerate very low temperatures in winter, including e.g.
freeze-drying. In practice this means MTCO is never above 0 ºC and the winters
are never warm. NOTE: “boreal” conditions can occur e.g. in the geographical
tropics, e.g. in mountains.
Arctic: has no known minimum temperature limits or require snow-cover to survive
winter conditions. NOTE: “arctic” conditions can occur on mountains, so we use
this term to cover “alpine”
Drought-tolerant: can sustain life through periods of >3 weeks when there is no plantavailable water.
Evergreen: maintains leaves throughout the year because leaves are replaced
continuously. NOTE: leaves do NOT have to be retained for more than one year
for the species to be classified as evergreen.
Drought-deciduous: loses leaves in response to drought conditions. This can be a regular
occurrence, with loss during the driest part of the year (true drought deciduous),
or an irregular occurrence during drought periods (i.e. includes the categories
“semi-deciduous” and “semi-evergreen”).
Cold-deciduous: regularly loses its leaves in the coldest season in response to cold. Note:
species which lose their leaves as a result of catastrophic/unusual weather
conditions but which would otherwise not do so ARE NOT considered cold
deciduous.
Leaves: for the purpose of the classification, leaves means functional leaves (i.e. would
include phyllodes that act as leaves)

Broadleaved: includes all potentially broad-leaved plants, including plants
with small-leaves and essentially leafless plants that exhibit stem photosynthesis

Needleleaved: includes true needles, scale-leaved and sheath-leaved
plants.
Malacophyll: soft leaves, with little protection against water loss from leaf surface and/or
stomata. In the field, can be bent without damage.
Sclerophyll: exhibits functional traits to minimise water loss (e.g. waxy coatings, reduced
stomatal density, hairs, leaf curling) or structural adaptations to lengthen leaf life
(e.g. rigidity, strengthening tissue). In the field, sclerophyll leaves will break or
crack when bent.
Shrubs: for the purpose of the classification, shrubs are multi-stemmed plants which are
generally < 3m high whereas trees are single-stemmed plants that are generally >
3m high. (I know this poses some problems with multi-stemmed trees in
Australia).
 Low to high shrub. Shrub that under optimal conditions will grow taller
than ca 0.5m
 Dwarf shrub: Shrub that under optimal conditions never grows taller than
ca 0.5m. Would include erect and prostrate forms, cushion shrubs etc.
 Small-leaved shrub: Shrub of any height that has leaves smaller than ca 5
mm long (i.e. pico-sized leaves). Characteristic of heathlands.
Resprouter: readily regenerates after damage by resprouting. Here our main emphasis is
damage by fire
Shade-tolerant: will regenerate under the canopy
There are some functional inconsistencies in these definitions (e.g. our definition of
needleleaved plants) and we might like to discuss these at the next meeting. However, to
take these into account, we would need to further subdivide our PFTs – something for a
later stage. For the moment, PLEASE stick to the definitions above. If you find
something that really doesn’t fit into an existing definition/PFT category, please identify
the problem. DO NOT try and fit it into the nearest definition/PFT category – we’ve done
that before and ….
We have two groups of taxa that we might want to consider for biomisation: mistletoes
and orchids. Mistletoes as diagnostic of e.g. temperate forests and orchids as diagnostic
of e.g. tropical forests. Comments on this would be welcome.
Having read this, we would like you to go through the attached Excel file carefully and
look at the taxa from your region. Please add missing information and correct any
mistakes that you can see (in colour, if possible). We have organised the three sheets so
that you only have to consider the information required for each PFT. PLEASE NOTE:
According to our preliminary classification, some taxa display different behaviour
patterns in different climates (e.g. tropical species are drought-tolerant while warmtermperate species are drought-intolerant); in these situations, the taxon has two entries in
the attached table. Where the behaviour pattern is the same except with respect to
temperature (i.e. obligate tropical, obligate warm-temperate species are both droughttolerant), then there is only one line entry. If you need to refine theone line entries, either
specify as a note at the end of the line or add a line showing the different behaviour
patterns.