The nebulous ecology of daisies, with respect to wildfire

(writing in progress)

Wildfire is an important aspect of the environment, for many types of vegetation and many species of plants.

Not only does combustion consume plant tissues, but it serves as a way of recycling nutrients.

Plants living in fire-prone environments have basically three adaptive options w.r.t. adaptation, viz.

• ignoring the detriments and benefits of combustion, and being adaptively neutral,
• being 'pyrophilic' in a loose sense overall, by being adapted to capitalise on combustion in various ways, or
• being 'pyrophobic' in a loose sense overall, by being adapted to minimise combustion, and to avoid its effects, both negative and positive.

Typical 'pyrophiles' are species that

• boost flammability so that their foliage ignites even in the green, living state,
• have modes of dispersal, sowing, germination, and growth that exploit the opportunities provided by fire, and
• capitalise particularly on the nutrients in ash.

Even at the level of families, plants tend to have typical trends w.r.t. the above framework.

For example, proteas (Proteaceae) tend to be pyrophilic, because they tend

• to be sclerophyllous, with leaves so lignified that they are flammable even when alive,
• to have infructescences adapted to combustion by means of bradyspory/serotiny, and
• to regenerate germinatively in episodes corresponding to the post-fire availability of ashbeds.

In this Post, I point out that daisies (Asteraceae) are strangely nebulous in their relationship to wildfire. It is almost as if this nebulousness is in itself a 'family characteristic' of daisies.

The following examples come to mind, in no particular order.

COASTAL SAGE SCRUB IN CALIFORNIA

Coastal sage scrub (https://esajournals.onlinelibrary.wiley.com/doi/abs/10.2307/1936680 and https://www.fs.usda.gov/psw/publications/4403/Vegetative.pdf) and coastal scrub (https://www.nps.gov/pore/learn/management/firemanagement_fireecology_vegtypes_coastalscrub.htm), under the mediterranean-type climate in California, contains daisies as some of its most important plants (e.g. Artemisia californica).

This vegetation is prone to wildfire (https://lpfw.org/wp-content/uploads/2020/01/Annotated-Bibliography-Chaparral-Wildfire_LPFW_January-2020.pdf). However, no daisy here, whether perennial or annual, shrubby or herbaceous, seems to be pyrophilic.

The main shrubby daisies (genera Artemisia, Emelia, and Baccharis) have foliage that is not particularly flammable, partly because the leaves tend to be shed during the warm, dry season. They regenerate vegetatively from the base of the shrub, but this occurs also in the intervals between wildfires. Seedlings occur in these intervals, rather than in ashbeds.

The annual/biennial daisies in coastal sage scrub seem to show scant relationship to wildfire (needs checking).
(writing in progress)

Posted on Δεκέμβριος 19, 2022 1211 ΠΜ by milewski