Locally extensive pre-Columbian human occupation and modification occurred in the forests of the central and eastern Amazon Basin, but whether comparable impacts extend westward and into the vast ...terra firme (interfluvial) zones, remains unclear. We analyzed soils from 55 sites across central and western Amazonia to assess the history of human occupation. Sparse occurrences of charcoal and the lack of phytoliths from agricultural and disturbance species in the soils during pre-Columbian times indicated that human impacts on interfluvial forests were small, infrequent, and highly localized. No human artifacts or modified soils were found at any site surveyed. Riverine bluff areas also appeared less heavily occupied and disturbed than similar settings elsewhere. Our data indicate that human impacts on Amazonian forests were heterogeneous across this vast landscape.
Global climate models suggest enhanced warming of the tropical mid and upper troposphere, with larger temperature rise rates at higher elevations. Changes in fire activity are amongst the most ...significant ecological consequences of rising temperatures and changing hydrological properties in mountainous ecosystems, and there is a global evidence of increased fire activity with elevation. Whilst fire research has become popular in the tropical lowlands, much less is known of the tropical high Andean region (>2000masl, from Colombia to Bolivia). This study examines fire trends in the high Andes for three ecosystems, the Puna, the Paramo and the Yungas, for the period 1982–2006. We pose three questions: (i) is there an increased fire response with elevation? (ii) does the El Niño‐ Southern Oscillation control fire activity in this region? (iii) are the observed fire trends human driven (e.g., human practices and their effects on fuel build‐up) or climate driven? We did not find evidence of increased fire activity with elevation but, instead, a quasicyclic and synchronous fire response in Ecuador, Peru and Bolivia, suggesting the influence of high‐frequency climate forcing on fire responses on a subcontinental scale, in the high Andes. ENSO variability did not show a significant relation to fire activity for these three countries, partly because ENSO variability did not significantly relate to precipitation extremes, although it strongly did to temperature extremes. Whilst ENSO did not individually lead the observed regional fire trends, our results suggest a climate influence on fire activity, mainly through a sawtooth pattern of precipitation (increased rainfall before fire‐peak seasons (t‐1) followed by drought spells and unusual low temperatures (t0), which is particularly common where fire is carried by low fuel loads (e.g., grasslands and fine fuel). This climatic sawtooth appeared as the main driver of fire trends, above local human influences and fuel build‐up cyclicity.
The extent and intensity of pre-Columbian impacts on lowland Amazonia have remained uncertain and controversial. Various indicators can be used to gauge the impact of pre-Columbian societies, but the ...formation of nutrient-enriched terra preta soils has been widely accepted as an indication of long-term settlement and site fidelity. Using known and newly discovered terra preta sites and maximum entropy algorithms (Maxent), we determined the influence of regional environmental conditions on the likelihood that terra pretas would have been formed at any given location in lowland Amazonia. Terra pretas were most frequently found in central and eastern Amazonia along the lower courses of the major Amazonian rivers. Terrain, hydrologic and soil characteristics were more important predictors of terra preta distributions than climatic conditions. Our modelling efforts indicated that terra pretas are likely to be found throughout ca 154 063 km2 or 3.2% of the forest. We also predict that terra preta formation was limited in most of western Amazonia. Model results suggested that the distribution of terra preta was highly predictable based on environmental parameters. We provided targets for future archaeological surveys under the vast forest canopy and also highlighted how few of the long-term forest inventory sites in Amazonia are able to capture the effects of historical disturbance.
Fire is an important and arguably unnatural component of many wet Amazonian and Andean forest systems. Soil charcoal has been used to infer widespread human use of landscapes prior to European ...Conquest. An analysis of Amazonian soil carbon records reveals that the records have distinct spatial and temporal patterns, suggesting that either fires were only set in moderately seasonal areas of Amazonia or that strongly seasonal and aseasonal areas are undersampled. Synthesizing data from 300 charcoal records, an age-frequency diagram reveals peaks of fire apparently coinciding with some periods of very strong El Niño activity. However, the El Niño record does not always provide an accurate prediction of fire timing, and a better match is found in the record of insolation minima. After the time of European contact, fires became much scarcer within Amazonia. In both the Amazonia and the Andes, modern fire pattern is strongly allied to human activity. On the flank of the Andes, forests that have never burned are being eroded by fire spreading downslope from grasslands. Species of these same forests are being forced to migrate upslope due to warming and will encounter a firm artificial fire boundary of human activity.
To present and analyse the literature sources regarding the management of Behçet disease (BD) identified during the systematic literature research, which formed the basis for the European League ...Against Rheumatism (EULAR) evidence-based recommendations for the management of BD.
Problem areas and related keywords regarding the management of BD were determined by the multidisciplinary expert committee commissioned by EULAR for developing the recommendations. A systematic literature research was performed using MedLine and Cochrane Library resources through to December 2006. Meta-analyses, systematic reviews, randomised controlled trials (RCTs), open studies, observational studies, case control studies and case series' involving > or = 5 patients were included. For each intervention the effect size and number needed to treat were calculated for efficacy. Odds ratios and numbers needed to harm were calculated for safety issues of different treatment modalities where possible.
The literature research yielded 137 articles that met the inclusion criteria; 20 of these were RCTs. There was good evidence supporting the use of azathioprine and cyclosporin A in eye involvement and interferon (IFN)alpha in mucocutaneous involvement. There were no RCTs with IFNalpha or tumour necrosis factor (TNF)alpha antagonists in eye involvement. Similarly controlled data for the management of vascular, gastrointestinal and neurological involvement is lacking.
Properly designed, controlled studies (new and confirmatory) are still needed to guide us in managing BD.
A continuous 48,000-year-long paleoecological record from Neotropical lower montane forest reveals a consistent forest presence and an ice-age cooling of ~5° to 9°C. After 30,000 years of ...compositional stability, a steady turnover of species marks the 8000-year-long transition from ice-age to Holocene conditions. Although the changes were directional, the rates of community change were no different during this transitional period than in the preceding 30,000-year period of community stability. The warming rate of about 1°C per millennium during the Pleistocene-Holocene transition was an order of magnitude less than the projected changes for the 21st century.
To develop evidence-based European League Against Rheumatism (EULAR) recommendations for the management of Behçet disease (BD) supplemented where necessary by expert opinion.
The multidisciplinary ...expert committee, a task force of the EULAR Standing Committee for Clinical Affairs (ESCCA), consisted of nine rheumatologists (one who was also a clinical epidemiologist and one also a Rehabilitation Medicine doctor), three ophthalmologists, one internist, one dermatologist and one neurologist, representing six European countries plus Tunisia and Korea. A patient representative was also present. Problem areas and related keywords for systematic literature research were identified. Systematic literature research was performed using Medline and the Cochrane Library databases from 1966 through to December 2006. A total of 40 initial statements were generated based on the systematic literature research. These yielded the final recommendations developed from two blind Delphi rounds of voting.
Nine recommendations were developed for the management of different aspects of BD. The strength of each recommendation was determined by the level of evidence and the experts' opinions. The level of agreement for each recommendation was determined using a visual analogue scale for the whole committee and for each individual aspect by the subgroups, who consider themselves experts in that field of BD. There was excellent concordance between the level of agreement of the whole group and the "experts in the field".
Recommendations related to the eye, skin-mucosa disease and arthritis are mainly evidence based, but recommendations on vascular disease, neurological and gastrointestinal involvement are based largely on expert opinion and uncontrolled evidence from open trials and observational studies. The need for further properly designed controlled clinical trials is apparent.
Not a single tree species distribution in the Amazon basin has been reliably mapped, though speculation regarding such distributions has been extensive. We present data from a network of 21 forest ...plots in Manu National Park, Peru, totaling >36 ha and sited over an area of ∼ 400 km2, to explore how tree species are distributed across upper Amazonia at a variety of spatial scales. For each of 825 tree species occurring in the plots we asked three questions: (1) Does the species have a large or small geographic range? (2) Is the species restricted to a single forest type, or is it found in several? (3) Is the species locally abundant anywhere or is it scarce everywhere? The answers served to classify a subset of species under Rabinowitz's classification scheme for rare species. Three main conclusions emerged. First, the great majority of tree species at Manu are geographically widespread. Every species identified to date occurs elsewhere in South America, outside the department of Madre de Dios; more than two-thirds of them have been collected 1500 km away in Amazonian Ecuador. Second, 15-26% of species appear to be restricted to a single forest type, when forest types are defined by historical river dynamics (i.e., terra firme forest, mature floodplain forest, swamp forest, and primary successional floodplain forest). The proportion of restricted species declined with increasing sampling effort, making 15% a more reliable figure. Third, while 88% of species occurred at densities of <1 individual/ha over the entire network of plots, at least half occurred somewhere at densities of >1.5 individuals/ha. Extrapolating these results provides a first guess at how tree species are distributed across the western portion of the Amazon basin. We conclude with the suggestion that most tree species in the region are habitat generalists occurring over large areas of the Amazonian lowlands at low densities but large absolute population sizes.
To investigate the palaeoecological changes associated with the last ice age, subsequent deglaciation and human occupation of the central Andes. Lake Pacucha, Peruvian Andes (13°36′26″ S, 73°19′42″ ...W; 3095 m elevation). Vegetation assemblages were reconstructed for the last 24 cal. kyr bp (thousand calibrated ¹⁴C years before present), based on pollen analysis of sediments from Lake Pacucha. An age model was established using ¹⁴C accelerator mass spectrometry dates on bulk sediment. Fossil pollen and sedimentological analyses followed standard methodologies. Puna brava replaced the Andean forest at the elevation of Lake Pacucha at the Last Glacial Maximum (LGM). Deglaciation proceeded rapidly after 16 cal. kyr bp, and near-modern vegetation was established by c. 14 cal. kyr bp. The deglacial was marked by the range expansion of forest taxa as grassland taxa receded in importance. The mid-Holocene was marked by a lowered lake level but relatively unchanged vegetation. Quinoa and maize pollen were found in the latter half of the Holocene. Temperatures were about 7-8 °C colder than present at this site during the LGM. The pattern of vegetation change was suggestive of microrefugial expansion rather than simple upslope migration. The mid-Holocene droughts were interrupted by rainfall events sufficiently frequent to allow vegetation to survive largely unchanged, despite lowering of the lake level. Human activity at the lake included a 5500-year history of quinoa cultivation and 3000 years of maize cultivation.
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