Geology Reports⌕ Search

Geology topics

William J. Bond

Publications and source records attributed to William J. Bond.

25 records · Page 2Linked to original sources
USGS2011

Climate, Fire and Geology in the Convergence of Mediterranean-type Climate Ecosystems

Integrating Climate, Fire and Geology in a Fire-prone World Fire challenges the long-standing hegemony of ecology, biogeography and paleoecology that climate and soils are sufficient to explain the origin and distribution of plant species. In a world where half of the land surface is fire-prone (Krawchuk et al . 2009), understanding the past and predicting the future requires a close integration of climate, fire and geology. The dogma that fire is an anthropogenic phenomenon of little use in understanding paleoecology (Axelrod 1980, 1989), or merely incidental to vegetation development (Hopper 2009), is rapidly being replaced with a better understanding of paleofire's impact on land plant evolution (Scott 2000; Pausas & Keeley 2009). Attempts to model future global vegetation patterns have been demonstrated to be inadequate without including both natural and anthropogenic fire regimes (Bond et al . 2005). Bond and Keeley (2005) outlined the conundrum posed by alternative explanations for the present distribution of vegetation and assembly of communities. Classical explanations have invoked resource-based mechanisms that are driven by climate and soils. There are ecosystems where resource-based mechanisms may be sufficient, but on many seasonally dry landscapes ecosystem processes such as fire play a major role in the organization and evolution of vegetation.

Book chapter↗
USGS2010

The Origins of C4 Grasslands: Integrating Evolutionary and Ecosystem Science

The evolution of the C 4 photosynthetic pathway from the ancestral C 3 pathway in grasses led to the establishment of grasslands in warm climates during the Late Miocene (8 to 3 million years ago). This was a major event in plant evolutionary history, and their high rates of foliage production sustained high levels of herbivore consumption. The past decade has seen significant advances in understanding C 4 grassland ecosystem ecology, and now a wealth of data on the geological history of these ecosystems has accumulated and the phylogeny of grasses is much better known. Edwards et al. (p. 587) review this multidisciplinary research area and attempt to synthesize emerging knowledge about the evolution of grass species within the context of plant and ecosystem ecology.

Science↗
USGS2009

Stem demography and post-fire recruitment of a resprouting serotinous conifer

The contribution of resprouts and seedling recruitment to post-fire regeneration of the South African fynbos conifer Widdringtonia nodiflora was compared eight months after wildfires in 1990. Stems on all trees were killed by fire but resprouting success was > 90 % at all but one site. A demographic study of burned skeletons revealed that prior to these fires, nearly all plants were multi-stemmed (4–9 stems/plant) and multi-aged, indicating continuous sprout production between fires. All stems were killed by these 1990 fires and at most sites > 90 % of the stems were burned to ground level. All diameter stems were susceptible to such incineration as, at most sites, there was no difference in average diameter of stems burned to ground level and those left standing. Individual genets usually had all ramets incinerated to ground level or all ramets charred, but intact, suggesting certain micro-sites burned hotter, whereas other sites were somewhat protected. Although not true of the 1990 fires, there was evidence that occasionally Widdring-tonia stems may survive fire. At one site, four of the 16 plants sampled had a burned stem twice as old as the oldest burned stem on the other 12 plants at the site, suggesting some stems had survived the previous fire (ca. 1970) and this conclusion was supported by fire-scars on these four stems that dated to ca. 1970. Based on the highly significant correlation between stem diameter and cone density left standing after the 1990 fires, we calculated that for most sites > 80 % of the initial cone crop was incinerated by fire. This is important because we observed a strong relationship between size of the canopy cone crop surviving fire and post-fire seedling recruitment. Under these conditions we hypothesize that sprouting confers a selective advantage to genets when fires cause heavy losses of seed. The infrequent occurrence of sprouting in the Cupressaceae suggests the hypothesis that resprouting is an apomorphic or derived trait in Widdringtonia. Data from this study suggests resprouting provides a selective advantage under severe fynbos fires, which are not only 'stand-replacing fires,’but also are intense enough to incinerate cone-bearing stems.

Journal of Vegetation Science↗
USGS2009

Fire in the Earth system

Fire is a worldwide phenomenon that appears in the geological record soon after the appearance of terrestrial plants. Fire influences global ecosystem patterns and processes, including vegetation distribution and structure, the carbon cycle, and climate. Although humans and fire have always coexisted, our capacity to manage fire remains imperfect and may become more difficult in the future as climate change alters fire regimes. This risk is difficult to assess, however, because fires are still poorly represented in global models. Here, we discuss some of the most important issues involved in developing a better understanding of the role of fire in the Earth system.

Science↗
USGS2005

Fire as a global ‘herbivore’: the ecology and evolution of flammable ecosystems

It is difficult to find references to fire in general textbooks on ecology, conservation biology or biogeography, in spite of the fact that large parts of the world burn on a regular basis, and that there is a considerable literature on the ecology of fire and its use for managing ecosystems. Fire has been burning ecosystems for hundreds of millions of years, helping to shape global biome distribution and to maintain the structure and function of fire-prone communities. Fire is also a significant evolutionary force, and is one of the first tools that humans used to re-shape their world. Here, we review the recent literature, drawing parallels between fire and herbivores as alternative consumers of vegetation. We point to the common questions, and some surprisingly different answers, that emerge from viewing fire as a globally significant consumer that is analogous to herbivory.

Trends in Ecology and Evolution↗
USGS2001

On incorporating fire into our thinking about natural ecosystems: A response to Saha and Howe

Ecologists long have had a fascination with fire impacts, although they have been slow to incorporate this ecological factor into serious thinking about the structure of communities and evolution of species (Bond and van Wilgen 1996). The remarks by Saha and Howe (2001, in this issue) illustrate some of the problems ecologists have in trying to apply fire to their thinking about natural ecosystems. Fire is commonly perceived qualitatively in terms of presence or absence, and the variation in frequency and intensity, as well as other components of the fire regime (e.g., fig. 1), is ignored. Often not considered is the fact that plant life histories are fine-tuned to particular fire regims, and in this regard, landscapes present a range of selective peaks and valleys, both figuratively and literally. Because landscape patterns affect the propagation of natural fires, it is imperative that the degree of human disturbance be considered (e.g. Marsh [1864] 1965; Gadgil and Guhu 1993) and the limitations of basing evolutionary arguments on anthropogenically derived landscapes be recognized (e.g., Janzen and Martin 1982).

American Naturalist↗