Summary: Ex igne ignis

Delving deep into wildfire’s primordial past illuminates the potentialities of its future. A complex phenomenon of which the behaviour can be understood not in the absence of interrogation of sciences that in ancient times were called ‘natural’, its role within the emergence and evolution of innumerable land-based organisms, and no less so than those of our own taxonomic lineage, could be no less fundamental. At the apex of Earth systems, wildfire constitutes a synecological unit, which comprised both slow and fast, abiotic and biotic variables reconfigures in space and time at scales local to global, momentary to epochal. But, for all its complexity, beholden to the laws of thermodynamics and mechanics, whereupon one knows of the biochemical, physical, ecological, and atmospheric conditions in which it ignites one can anticipate the range of behaviours it may manifest. The most heterogeneous of all the natural hazards, manifold are the means by which it is monitored, and in turn, its behaviours categorised. As relates to the latter, while knowledge of the range thereof has been essential in establishing the extent to which wildfire behaviours past, present, and possible future are understood at multiple spatiotemporal scales, the foremost relevant to the task of developing a new WUI paradigm are fire regimes, intensities, and severities.

Indigenous to the case study regions, the low-severity, mixed-severity, and high- severity fire regimes are both quantitatively and qualitatively distinct in their behaviours and ecological, and wider environmental legacies. Their spatiotemporal parameters determined by factors including climate, elevation, topography, and species tolerances thereto, the regimes observed in the ecoregions types Temperate Coniferous Forests, and Mediterranean Forests, Woodlands, and Scrubs of the western U.S., reside not in a state of stasis, but of cyclical change.

Burning at the level of ground, surface, or crown within the biomass stratum, wildfire behaviour is shaped factors including weather; topography; fuel-type, size, shape, and state, including moisture content, loading, compactness, chemical properties, horizontal continuity, and vertical arrangement. Spreading not uniformly within the landscape, in all but the most extreme cases, the low, mixed, and high severity fire regimes create ecological mosaics, therein diversity in biomass age, structure, and vulnerability to future wildfires, together with seed banks that repopulate burned areas upon wildfire’s passing.

Having coevolved with wildfire, species native to these, and other fire-prone regions exhibit a range of morphological, biochemical, physiological, phenological, and/or behavioural traits that enable them to coexist within historical fire return intervals, intensities, and behaviours more generally. Functionally classifiable as either fire- tolerant or fire-resistant, fire-adapted biota exhibit one of three primary ‘modes of persistence’ (Rowe, 1983):

• Regenerating through their perennating parts and seedling recruitment, endurers, such as Canyon live oak, have evolved traits that enable them to persist in low to mixed severity fire regimes that return with frequency, but relatively low intensity.

• Though parent plants succumb to fire, evaders, such as Lodgepole pine, have evolved traits that enable them to persist in mixed to high severity fire regimes, where their seedlings rapidly repopulate the nutrient abundant post- fire landscapes.

• Protected by an array of pyro-armoury and defence behaviours, such as thick bark and biochemical mechanisms, resistors, such as Ponderosa pine, have evolved traits that enable them to persist in low to mixed severity fire regimes of relatively high frequency.

The foremost functional traits exhibited by fire-resilient species are pyriscence [fire- stimulated seed release], pyrogermination [fire-stimulated germination], abscission [shedding of parts], retardant rhytidome [thick/plated bark], and resprouting [re- colonisation through cloning].

While many are the fire-adapted faunal species on Earth, descendants of the superfamily Hominoidea, humans, are the foremost. Having stepped bipedally-forth from the forest to the geologically recent East African plains in the Mid-Late Miocene, our ancestors increasingly integrated fire in to the various facets of their lives. They followed fire. They foraged fire. They forged fire. Upon doing so they left archaeological, anthropological, physiological, genealogical, and other biological fragments which, collectively, illuminate our coevolution with fire.

Ab antique, wildfire and its regimes have followed the rhythm of the seasons, which reconfiguring in epochal time, ‘dance’ not to the tune of mere mortals. Whether MST increases by 1°C, 2°C, 3°C, or more, de futuro, within both the case study regions, and other Mediterranean and temperate forests, woodlands, and scrublands worldwide, theoretical and computer modelling suggests wildfire frequencies will increase.

Put succinctly, as Cedric Price may have said, before long it appears a very many more that live both within and beyond the wildland urban interface are about to become members of a very ‘Hot Stuff Club’. Might the wildland urban interface of 2030, 2050, or 2070 look like a still from Nebraskan architecture graduate Joshua Puppe’s ‘The Authors’ visual story [Fig. 42] and, more generally, how might humanity’s relationship with fire develop in the decades to come?

>Continue to Chapter 4.7 here.

The thesis is also available in PDF format, downloadable in several parts on Academia and Researchgate.

Note that figures have been removed from the digital version hosted on this site, but are included in the PDFs available at the links above.

Citation: Sterry, M. L., (2018) Panarchistic Architecture: Building Wildland-Urban Interface Resilience to Wildfire through Design Thinking, Practice and Building Codes Modelled on Ecological Systems Theory. PhD Thesis, Advanced Virtual and Technological Architecture Research [AVATAR] group, University of Greenwich, London.