Amazon Rain-Forest Fires

Sanford, Robert L.; Saldarriaga, Juan F.; Clark, Kathleen; Uhl, Christopher; Herrera, R.

doi:10.1126/science.227.4682.53

Cited by 333 publications

(149 citation statements)

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“…Previous studies suggest that, under natural conditions, major fires are rare in Amazonian terra-firme forests, perhaps occurring only once or twice per millennium on average (Meggers 1994, Piperno & Becker 1996, Saldarriaga & West 1986, Sanford et al 1985. At Tailândia, however, fires in intact forest interiors appeared to occur more frequently than this, with observed burns implying fire return-intervals of 100-150 y (Figure 3).…”

Section: Generality and Limitations Of Findingsmentioning

confidence: 88%

Fire as a large-scale edge effect in Amazonian forests

2002

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ABSTRACT. Amazonian forests are being rapidly cleared, and the remaining forest fragments appear unusually vulnerable to fire. This occurs because forest remnants have dry, fire-prone edges, are juxtaposed with frequently burned pastures, and are often degraded by selective logging, which increases forest desiccation and fuel loading. Here we demonstrate that in eastern Amazonia, fires are operating as a large-scale edge effect in the sense that most fires originate outside fragments and penetrate considerable distances into forest interiors. Multitemporal analyses of satellite imagery from two frontier areas reveal that fire frequency over 12-14-y periods was substantially elevated within at least 2400 m of forest margins. Application of these data with a mathematical core-area model suggests that even large forest remnants (up to several hundred thousand ha in area) could be vulnerable to edge-related fires. The synergistic interactions of forest fragmentation, logging and human-ignited fires pose critical threats to Amazonian forests, particularly in more seasonal areas of the basin.

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Section: Generality and Limitations Of Findingsmentioning

confidence: 88%

Fire as a large-scale edge effect in Amazonian forests

2002

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“…Its occurrence indicates that fire in tropical forests -recently shown to be important in certain seasonal lowland areas of the Neotropics and Paleotropics (Huber etal. 1984;Sanford et al 1985;Leighton and Wirawan 1986) -can shape plant evolution even in wet montane sites. Functionally similar grown forms, apparently favored by similar conditions of fire over sterile substrates, occur in Vellozia (Velloziaceae) and Xanthorrhoea and Kingia pCanthorrhoeaceae).…”

Section: Discussionmentioning

confidence: 99%

Fire adaptation in Neblinaria celiae (Theaceae), a high-elevation rosette shrub endemic to a wet equatorial tepui

1986

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Summary. Neblinaria celiae (Theaceae), a rosette shrub endemic to the exceedingly rainy summit of remote Cerro de la Neblina in southern Venezuela, has a previously undescribed set of adaptations to fire. Its growth form entails sparse branching, massive terminal leaf rosettes, and thick bark. It is highly fire-tolerant, with a survival rate of 93% in a stand recently ignited by lightning, vs. 0% in seven co-occurring woody species. Survival increases sharply with rosette height, favoring a sparsely branched habit that would maximize the rate of upward growth through the sparse fuel layer supported by a sterile substrate. Thick bark and massive rosettes help protect cambial and foUar meristems from brief exposure to high temperatures. Rosettes on shorter plants are exposed to greater damage from fire near the ground and, as expected, are bigger and impound more rainwater; the greater number of leaves nearly balances the greater leaf mortality caused by fire. We relate Neblinaria's growth form to its dominance atop Neblina, to a general model for the evolution of sparse branching, and to the evolution of growth form in other tepui plants.Key words: Fire -Rosette shrubs -Tropical-alpine vegetation -Nebhnaria -Guayana HighlandsThe Guayana Highlands of northern South America are of considerable evolutionary interest. The isolated, cHfflined summits of the tepuis, or sandstone table mountains, of this region support floras with a high incidence of local endemism and unusual growth forms (Gleason 1931;Steyermark 1966Steyermark , 1967 Maguire 1967, 1972;Maguire 1970). One of the most bizarre growth forms found on these extremely humid and infertile summits is that 0Î Neblinaria celiae Maguire (=Bonnetia maguireorum Steyermark) (Theaceae :Bonnetioideae), known only from plateaus at 1,700-2,200 m elevation on Cerro de la Neblina (0°50'N, 66° O'W) in southernmost Venezuela (Maguire 1955;Maguire et al. 1972; Cronquist 1980;Steyermark 1984). Neblinaria is monotypic, with closest relatives in the large genus Bonnetia and related segregates Neogleasonia and Neotatea (Maguire 1955(Maguire , 1970 Maguire 1967, 1972;Maguire et al. 1972;Steyermark 1984).Neblinaria is an unbranched to sparsely branched, canOffprint requests to: T.J. Givnish delabra-Uke woody plant, 1-3 m -in height, with massive, artichoke-Ufe leaf rosettes surmounting each ascending branch ( Fig. 1 a, b). Its bark is extremely thick (ca. 1 to 4 cm), spongy, and deeply fissured (Fig. 1 c). Neblinaria often is quité common, forming nearly monospecific stands over leached sandstone on the mist-drenched plateaus of Neblina (Fig. 1 d). We thus became interested in determining what ecological factors may have favored the evolution of its tmusual growth form and its current dominance. TheoryTwo sets of factors might favor an unbranched or sparsely, branched habit. First, such a growth form could be favored by any factor that places a strong selective premium on height growth, because branching diverts energy from a plant's leader and tends to decrease height growth, at...

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“…As inter-annual drought episodes lengthen, accelerating tree mortality could build fuel loads for fires. Radiocarbon-dated soil charcoal collected from forest soils throughout Amazonia have led other authors to conclude that successive strata were laid by burns occurring one to many centuries apart since the last glacial maximum (Sanford et al, 1985;Saldarriaga & West, 1986;Bassini & Becker, 1990;Turcq et al, 1997). The presence of charcoal in soils at Marajoara suggests that fire, whether occurring at intervals decades or centuries wide, does indeed play some role in forest dynamics in southeast Pará (Meggers, 1994).…”

Section: Forest Disturbancementioning

confidence: 99%

Physiographic and floristic gradients across topography in transitional seasonally dry evergreen forests of southeast Pará, Brazil

Grogan

Galvão²

2006

Acta Amaz.

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Seasonally dry evergreen forests in southeast Pará, Brazil are transitional between taller closed forests of the interior Amazon Basin and woodland savannas (cerrados) of Brazil's south-central plains. We describe abiotic and biotic gradients in this region near the frontier town of Redenção where forest structure and composition grade subtly across barely undulating topography. Annual precipitation averaged 1859 mm between 1995-2001, with nearly zero rainfall during the dry season months of June -August. Annual vertical migrations of deep-soil water caused by seasonal rainfall underlie edaphic and floristic differences between high-and low-ground terrain. Low-ground soils are hydromorphic, shaped by perching water tables during the wet season, pale gray, brown, or white in color, with coarse texture, low moisture retention during the dry season, and relatively high macro-nutrient status in the surface horizons. Forest canopies on low ground are highly irregular, especially along seasonal streams, while overstory community composition differs demonstrably from that on high ground. High-ground soils are dystrophic, well-drained through the wet season, brown or red-yellow in color, with finer texture, higher moisture retention, and low macro-nutrient status in the surface horizons compared to low-ground soils. Forest canopies are, on average, taller, more regular, and more closed on high ground. Lowground areas can be envisioned as energy and nutrient sinks, where, because of hydrologic cycles, canopy disturbance likely occurs more frequently than at high-ground positions if not necessarily at larger scales.

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Amazon Rain-Forest Fires

Cited by 333 publications

References 8 publications

Fire as a large-scale edge effect in Amazonian forests

Fire as a large-scale edge effect in Amazonian forests

Fire adaptation in Neblinaria celiae (Theaceae), a high-elevation rosette shrub endemic to a wet equatorial tepui

Physiographic and floristic gradients across topography in transitional seasonally dry evergreen forests of southeast Pará, Brazil

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