4.4.2 Case Study #2: 2003 Southern California Fire Complex

“There are historical accounts of even larger fire events”. Keeley et al, 2004.

The southern Californian wildfires of October 2003 [Fig. 33] may be considered as emblematic of a transition from the regional fire regimes of the Holocene to those of the Anthropocene. Historically, the areas through which the fires passed, of which 95% were chaparral shrublands, the remainder mixed conifer forests, had sustained frequent, but generally low-intensity surface fires (Keeley et al, 2004). However, as in the case of YNP, several decades of fire exclusion and suppression had caused changes in both biome-type’s biomass density and composition, thus the wildfire frequencies, intensities, and severities, as would ultimately result therefrom. In the mixed conifer forests the biomass build-up facilitated the potential for a transition from surface fires to ladder-fuel-facilitated stand-replacing crown fires. Likewise, though their comparatively lower fuel loads rendered the chaparral shrublands a little more resilient to fire-regime change, fire exclusion and suppression had paced the way for fire-intensities that exceeded they of the regime (Lentile et al, 2007).

However, such was severity of the drought that preceded the October 2003 wildfires as to suggest that, whether young or old stands, even indigenous species of the lowest density woodlands and shrublands would have been severely moisture-stressed, therein, in at least some instances, not merely tinder-ready, but less physiologically able to withstand fire. The possibility thereof is supported by studies that found that, in some chaparral areas, vegetative-thinning, including removal of dead biomass, has not the capacity to reduce fire frequencies (Conrad and Weise, 1998; Keeley and Fotheringham, 2001; Moritz, 2003).

The timing of the southern California 2003 fires was atypical for the region, coinciding with the onset of the Santa Ana autumnal winds, of which the speeds [50- 60 m/p/h] enable rapid fire spread (Keeley et al, 2004) [Fig. 37]. Therein, true to regional fire form, weather played a predominant role in the spatiotemporal curation of the fires. Although, since reliable records began in the early 1930s, the fires were, then, unprecedented in their scale, they were well within the historical range as preceded the onset of suppression policies, as evidenced by a fire complex of some 3x their size that burned through Orange Country in late September 1889 (Ibid).

Topographically, the landscapes through which the 2003 fires spread include both rolling and steep hills and mountainous slopes, this being a factor that in combination with fire-severity, intensity, and pre-existing species communities, contributed to post-fire recovery patterns. In chaparral landscapes, “within the first few days or weeks”, post-fire root sprouting, seeding, and germination occurred (Lentile et al, 2007, p.96). However, unlike YNP’s post-1988-fire recovery, non-native species were abundant in some areas (Ibid), which in the instance of grasses would increase the probability of shortening the fire-cycle. Nonetheless, within a few seasons, chaparral shrubs and forbs had repopulated many sites to near pre-2003 biomass levels, therein restocked fire’s fuel supply.

Southern California’s mixed conifer forests fared less well, as is exemplified by the post-fire recovery of Cuyamaca Rancho State Park. Barely burned since 1911, the park’s forest-understory was abundant in shade-tolerant species of which the population would have been lower but for the relative absence of fire due to suppression policies. Hence, when the fires finally did arrive intense crowd fires ensued, and with them a tree mortality rate of 98% of mature conifers (Brennan, 2013). Furthermore, fire intensity was so great that, in contrast to the mosaic the historical fire regime had produced, the 2003 fires, or more specifically, the Cedar Fire, “levelled” 95% of the park’s forest (Ibid). Thus, indigenous species, such as the Coulter pine, which have evolved to repopulate the post-fire environment created by the low to mixed-severity fire regime, hence the hybrid nature of their seed populations [part serotinous, part wind-dispersed] are now contending with the high- severity regime, which presents the advantage of the mineral-rich soils to which its species is adapted, but the risk that its next generation of saplings, which have limited fire and drought resilience, will succumb to the now fast-changing elements.

There is a sad irony to the legacy of the state’s fire suppression policies and affiliated regional and national public communications campaigns, and in particular that of “Smokey the Bear”, which born of the misconception that truly ‘wild’ fire puts forests at risk has, in effect, contributed to their demise, thus to the habitat of “Smokey’s” real-world equivalent, American black bears (Ursus americanus), and other iconic North American fauna including Mountain Lions [Puma concolor], Bobcats [Lynx rufus], Coyotes [Canis latrans], and innumerable reptiles, birds, insects, and small mammals.

Not merely regionally, but nationally, land management and policy has been a highly contentious issue throughout the period of European settlement. Whereas, in California, and beyond, historically, indigenous peoples exhibited like-minded approaches to the lands in which they lived, they as removed said peoples to ‘reserves’ have exhibited wide-ranging opinions on their environment and its workings. As discussed earlier, severalfold are the underpinnings thereof. However, that swathes of America’s rural dwellers are sceptical of some within the scientific community, and of ‘conservationists’ in particular, is neither incidental nor accidental. In the U.S., as in many regions of the world, all-too-often has hands-on understanding of environmental issues been derided, as still remains the case today. Where the environment is concerned, and no less so than in respect of natural hazards, all the hypothesizing in the world compensates not for eye-witness accounts, first-hand knowledge of landscapes, and of their ecological assemblies, and historical, as well as present-day insights. In the absence thereof ‘fire gods’ are limited in their capacity to fully understand, let alone perceive of plausible means of adapting to ‘Pandorian’ scenarios, as presented by wildfire, and all genres of hazard as are labelled ‘natural’.

Southern California [sCA] is, and always has been, a territory in transition. In the evolutionary scheme of things, as discussed earlier, species, and in turn fire regimes come and go. The matter thereof would have no particular significance to humanity, but for the fact that both our present, and all past civilisations are subsidiaries thereof, thus fail whereupon environmental, and in turn evolutionary changes occur faster than we can adjust the parameters of the policies and codes by which we live.

As in the aftermath of the YNP 1988 fires, falling trees and debris, mudslides and rockslides were commonplace following of the 2003 sCA fire complex. While perpetually water-stressed, such is the shift in the state’s hydrological systems, and the extent of the effects of extreme wildfires thereupon, as to pose serious threat to the viability of the continued habitation of some state regions.

Extreme though they were, the 2003 fires were but a warm-up act, for not merely would 2007 deliver another [recent] history-making fire complex, but one of which the overall footprint was over 230,000 acres bigger.

>Continue to Chapter 4.4.3 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.