The recent fire history of the Table Mountain National Park and implications for fire management

Abstract

This paper provides an assessment of fire regimes in the Table Mountain National Park over the past four decades. We compiled a GIS database of all fires between 1970 and 2007 and analysed the fire regime in terms of the frequency, season and size of fires and the relationship between fire occurrence and fire weather. Most fires (90.5% of area burnt) occurred in summer and autumn, the ecologically acceptable season for fires. However, mean fire return intervals declined by 18.1 years, from 31.6 to 13.5 years, between the first and last decades of the record respectively. The area subjected to short (≤ six years) intervals between fires covered > 16% of the park in the last two decades of the record, compared to ~ 4% in the first two decades. A relatively small number of large fires dominated in terms of area burnt. Of the 373 fires recorded, 40 fires > 300 ha burnt 75% of the area, while 216 fires < 25 ha burnt 3.4% of the area. Fires occurred under a wide range of weather conditions, but large fires were restricted to periods of high fire danger. Prescribed burning was a relatively unimportant cause of fires, and most (> 85%) of the area burnt in wildfires. Areas subjected to short fire return intervals should be considered for management interventions. These could include the re-establishment of extirpated fire-sensitive species, the clearing of invasive alien plants and increased precautions for the prevention or rapid suppression of future accidental fires.

Intensifying postfire weather and biological invasion drive species loss in a Mediterranean-type biodiversity hotspot

“…Note that graminoids are typically separated from herbs in Fynbos studies because this component is dominated by species with tough perennial photosynthetic stems and reduced leaves in the families Restionaceae and Cyperaceae (37,54). The date and number of fires experienced by each plot were obtained from the original surveys (37,46) and the Table Mountain National Park fire database (23). Data on alien species' presence and density were obtained from two studies that enumerated all woody alien species in 183-m radii around the plots in 1966 (42) and over the period 1976-1980 (43), ranked into abundance classes of 0; 1-49; 50-199; and 200+ individuals.…”

“…Covariates included change in postfire age between surveys (continuous), the most extreme CHD (2 approximately even categories: 0-5 and 5+; range = 2-8) experienced in the first summer after fire by each plot between vegetation surveys, the maximum alien plant densities (four categories), and the local extinction, stability, or colonization by serotinous tall shrubs (three categories). We did not explore the influence of differences in the number, return time, or season of fires experienced by the plots, because they did not exceed expected natural variation (23).…”

“…Many resprout from storage organs or retain seeds in fireproof (serotinous) cones that open after fire, whereas others use dispersal vectors such as ants or rodents to facilitate underground storage of seed, later triggered to germinate by heat or smoke (20). Postfire weather conditions and the frequency, season, and intensity of fires are important determinants of vegetation structure and composition (21,22), and there is increasing concern that these properties of the disturbance regime are changing, resulting in altered ecosystems and biodiversity loss (7,21,23).…”

Driving forces of global wildfires over the past millennium and the forthcoming century

“…Today fires continue to directly influence human society and affect global climate. With a recent rise in the incidence of large uncontrolled fires, occurring regardless of national firefighting capacities (1,(3)(4)(5)(6)(7), concerns have grown about how climate change and human activities might impact future fire regimes. However, it is still unsettled whether climate or direct anthropogenic influence (fire ignition and suppression) are more important in determining global fire trends (1).…”

Temporal biodiversity change in transformed landscapes: a southern African perspective

“…Because pines are serotinous, fires stimulate seed release and soil-stored seeds are stimulated to germinate by fire. An increase in fire frequencies in the region (Forsyth & van Wilgen 2008) and an absence of seed-feeding biological control agents (because of industry concerns) suggest that substantial additional transformation of this area by pines, which form dense stands even in the absence of other human disturbance, can be expected (van Wilgen 2009b). If fynbos is to be conserved, in keeping with various conservation strategies for the country, the costs of unplanned fires in the region could amount to an additional US$ 13 million annually (i.e.…”