Showing papers by "William F. Laurance published in 2000"

Rainforest fragmentation kills big trees

Abstract: In tropical forests, large canopy and emergent trees are crucial sources of fruits, flowers and shelter for animal populations1,2. They are also reproductively dominant2 and strongly influence forest structure, composition, gap dynamics, hydrology2 and carbon storage3. Here we show that forest fragmentation in central Amazonia is having a disproportionately severe effect on large trees, the loss of which will have major impacts on the rainforest ecosystem.

Amazonian Tree Mortality During the 1997 El Niño Drought

Abstract: In 1997, the Amazon Basin experienced an exceptionally severe El Nino drought. We assessed ef- fects of this rare event on mortality rates of trees in intact rain forest based on data from permanent plots. Long-term (5- to 13-year) mortality rates averaged only 1.12% per year prior to the drought. During the drought year, annual mortality jumped to 1.91% but abruptly fell back to 1.23% in the year following El Nino. Trees dying during the drought did not differ significantly in size or species composition from those that died previously, and there was no detectable effect of soil texture on mortality rates. These results suggest that intact Amazonian rainforests are relatively resistant to severe El Nino events.

Forest loss and fragmentation in the Amazon: implications for wildlife conservation.

Abstract: Amazonian forests are experiencing rapid, unprecedented changes that are having major impacts on wildlife, regional hydrology and the global climate. Rates of deforestation and logging have accelerated in recent years and patterns of forest loss are changing, with extensive new highways providing conduits for settlers and loggers into the heart of the Amazon basin. These myriad changes are causing widespread fragmentation of forests. Fragmented landscapes in the Amazon experience diverse changes in forest dynamics, structure, composition and microclimate, and are highly vulnerable to droughts and fires—alterations that negatively affect a wide variety of animal species. In human-dominated lands intensive hunting may interact synergistically with fragmentation to further threaten wildlife populations.

Mega-Development Trends in the Amazon: Implications for Global Change

Abstract: This paper describes four global-change phenomena that are having major impacts on Amazonian forests. The first is accelerating deforestation and logging. Despite recent government initiatives to slow forest loss, deforestation rates in Brazilian Amazonia have increased from 1.1 million ha yr−1 in the early 1990s, to nearly 1.5 million ha yr−1 from 1992–1994, and to more than 1.9 million ha yr−1 from 1995–1998. Deforestation is also occurring rapidly in some other parts of the Amazon Basin, such as in Bolivia and Ecuador, while industrialized logging is increasing dramatically in the Guianas and central Amazonia.

Stinging Trees and Wait-a-Whiles: Confessions of a Rainforest Biologist

Abstract: The last traces of Australia's tropical rainforest, where the southeasterly winds bring rain to the coastal mountains, contain a unique assemblage of plants and animals, some primitive, many that are found nowhere else on earth. And fifteen years ago, they also contained Bill Laurance, a budding ecologist seduced by the nature of the landscape in north Queensland. Laurance isn't your typical scientist: he wears cut-offs instead of white coats, enjoys the occasional food fight, and isn't afraid to speak his mind, even if it gets him into trouble, as it often did in the Australian rainforest and as he recounts in his marvelous Queensland journal "Stinging Trees and Wait-a-Whiles."The book is his record of the time he spent in this remote area and his run-ins with plant, animal, and human species alike. Laurance lived in a tiny town of loggers and farmers, and he witnessed firsthand the impact of conservation issues on individual lives. He found himself at the center of a bitter battle over conservation strategies and became not only the subject of small-town gossip but also the object of many residents' hatred. Keeping ahead of his high-spirited young volunteers, hounded by the drug-sniffing local policeman, and all the while trying to further his own research amid natural and unnatural obstacles, Laurance offers us a personal and hilarious account of fieldwork and life in the Australian outpost of Millaa Millaa. "Stinging Trees and Wait-a-Whiles" is a biology lesson, a conservation primer, and an utterly energetic story about an impressionable young man who wound up at the epicenter of an issue that tore a small town apart.

Reply from W.F. Laurance.

Abstract: Ickes and Williamson1xEdge effects and ecological processes – are they on the same scale? Ickes, K and Williamson, GB Trends Ecol Evol 2000; 15: 373Abstract | Full Text | Full Text PDF | PubMedSee all References make some interesting points and I accept their conclusion that the extirpation of large predators, in addition to an artificially increased food supply, has contributed to the hyperabundance of pigs at Pasoh Forest Reserve in Malaysia The work supporting their conclusion is not yet published and I had based my interpretation on the forthcoming paper by Peters2xSee all References, who did not suggest the absence of large predators as a potential cause of increased pig numbers As I emphasized in my original article, the extirpation of large predators in isolated nature reserves, such as Pasoh, could certainly have important ecological effects3xEdge effects and the extinction of populations inside protected areas Woodroffe, R and Ginsberg, JR Science 1998; 280: 2126–2128Crossref | PubMed | Scopus (816)See all References, 4xMesopredator release and avifaunal extinctions in a fragmented system Crooks, KR and Soule, ME Nature 1999; 400: 563–566Crossref | Scopus (819)See all ReferencesHowever, I do not agree with Ickes and Williamson’s suggestion that the evidence linking elevated pig disturbances with the proliferation of Clidemia hirta at Pasoh is ‘purely circumstantial’ Peters2xSee all References showed quite clearly that Clidemia was mainly associated with sites having past soil disturbance, as well as treefall gaps, which had evidently been disturbed by pig rooting In this sense, pigs definitely appear to be facilitating the germination and establishment of this tropical weed In addition, Ickes and Williamson are overly simplistic in attributing the collapse of canopy–tree recruitment in Indonesia’s Gulung Palung National Park solely to an influx of bearded pigs Many other species – various primates, rodents, birds and insects – are also nomadic seed predators and probably contributed to the dramatic reduction in canopy–tree recruitment5xVertebrate responses to spatiotemporal variation in seed production of mast-fruiting Dipterocarpaceae Curran, LM and Leighton, M Ecol Monogr 2000; 70: 101–128CrossrefSee all References, 6xExperimental tests of the spatiotemporal scale of seed predation in mast-fruiting Dipterocarpaceae Curran, LM and Webb, CO Ecol Monogr 2000; 70: 129–148CrossrefSee all ReferencesAside from these details however, Ickes and Williamson and I are in complete agreement: edge effects may be occurring over far larger spatial scales than has previously been appreciated Their suggestion that large-scale ecological processes might be particularly prone to far-reaching edge effects is an insightful hypothesis and could help focus future research efforts I also agree with their proposition that the nature of the surrounding modified matrix can strongly influence edge effects and fragment dynamics – a conclusion supported by recent studies7xEcology and management of fragmented tropical landscapes Laurance, WF and Gascon, C Biol Conserv 1999; 91: 101–247Crossref | Scopus (25)See all References Indeed, I propose that we broaden the definition of ‘edge effect’ to include not only those phenomena in the immediate vicinity of forest edges but also the broader array of fragment–matrix interactions, at least insofar as these changes penetrate into fragments and disrupt natural processesI believe that many ‘fragmentologists’, myself included at times, have been somewhat myopic in their thinking about edge effects This has caused them to focus on small-scale phenomena that are obvious and easy to study, while potentially missing the bigger picture I have little doubt that we will find more large-scale edge effects once we start to look for them The key goal now is to study these phenomena, and to try to determine their ubiquity and importance