Northwestern Amazonia Research Articles

Variation in photosynthetic and nonphotosynthetic vegetation along edaphic and compositional gradients in northwestern Amazonia

Abstract. Tropical forests vary substantially in aboveground properties such as canopy height, canopy structure, and plant species composition, corresponding to underlying variations in soils and geology. Forest properties are often difficult to detect and map in the field, however, due to the remoteness and inaccessibility of these forests. Spectral mixture analysis of Landsat imagery allows mapping of photosynthetic and nonphotosynthetic vegetation quantities (PV and NPV), corresponding to biophysical properties such as canopy openness, forest productivity, and disturbance. Spectral unmixing has been used for applications ranging from deforestation monitoring to identifying burn scars from past fires, but little is known about variations in PV and NPV in intact rainforests. Here we use spectral unmixing of Landsat imagery to map PV and NPV in northern Amazonia, and to test their relationship to soils and plant species composition. To do this we sampled 117 sites crossing a geological boundary in northwestern Amazonia for soil cation concentrations and plant species composition. We then used the Carnegie Landsat Analysis System to map PV and NPV for these sites from multiple dates of Landsat imagery. We found that soil cation concentrations and plant species composition consistently explain a majority of the variation in remotely sensed PV and NPV values. After combining PV and NPV into a single variable (PV–NPV), we determined that the influence of soil properties on canopy properties was inseparable from the influence of plant species composition. In all cases, patterns in PV and NPV corresponded to underlying geological patterns. Our findings suggest that geology and soils regulate canopy PV and NPV values in intact tropical forests, possibly through changes in plant species composition.

The languages of the Amazon by Alexandra Y. Aikhenvald (review)

Reviewed by: The languages of the Amazon by Alexandra Y. Aikhenvald Eithne B. Carlin The languages of the Amazon. By Alexandra Y. Aikhenvald. Oxford: Oxford University Press, 2012. Pp. xxxiii, 514. ISBN 9780199593569. $160 (Hb). As stated in the preamble, the general aim of The languages of the Amazon is to provide linguists, anthropologists, students of Latin American studies, and the general reader with an introduction to the salient features and linguistic gems of the native languages of Amazonia in an accessible form, and in this Alexandra Y. Aikhenvald has certainly succeeded. Throughout the book the reader is exposed to A’s palpable passion for Amazonian languages, which grew out of her own field experience working on eight languages from three different language families, and from the high degree of linguistic complexity and quirkiness that Amazonian languages exhibit, often contradicting assumed universals. Drawing on the upsurge over the last twenty-five years of scholarly interest in the languages of this hotspot of linguistic diversity—c. 350 languages found in fifteen language families, and perhaps as many as thirty isolates—A provides us with a well-organized, highly readable, and lively book containing fourteen chapters, several tables and diagrams, eighteen maps, a glossary of terms used, and three indices to search for subjects, languages and language families, and authors. The list of references covers forty-six pages. Several chapters include a final section giving general historical or ethnographic references for the reader to consult, while at the same time pointing out dubious sources that should be avoided. In addition, six of the chapters have boxed insets with extra factual information and/or anecdotes that spice up the book. The book begins with a general introduction to Amazonia (Ch. 1) that includes an overview of the language families, the peoples and their demographics, and histories pre- and postconquest. The appendix to Ch. 1 consists of a list of native American words that were borrowed into European languages, such as Cariban manatee ‘large aquatic mammal’ (manati/manatï ‘breasts’), which is attested in Spanish by 1535 and in English by 1555. Ch. 2 offers a discussion of linguistic areas and the sometimes virulent language contact situations in Amazonia. The author distinguishes only one ‘long-standing linguistic area’ (73) in Amazonia, namely the Vaupés River Basin, on which she has previously published extensively, and one incipient linguistic area, or as she calls it a ‘contact zone’ (86), namely the Upper Xingu. The purported status of the Guaporé-Mamoré Basin as a linguistic area is left unresolved. A had already pointed out in Ch. 1 the need for linguists to be aware of and take into account the complex contact histories of Amazonian peoples, both pre- and post-European outthrust, since language shift and substrate phenomena are ubiquitous, often resulting from traditional kidnapping practices. The remainder of the book follows the structure of what one would find in a descriptive grammar: phonologies, including unusual sounds and gaps in sound systems (Ch. 3); typology of word structure and word classes (Ch. 4); properties of nouns, including possession (Ch. 5); properties and versatility of verbs (Ch. 6); grammatical relations and argument structure (Ch. 7); valency-changing strategies such as passives, causatives, and applicatives (Ch. 8); evidentiality (Ch. 9); genders, noun classes, and classifiers showing how the world is categorized (Ch. 10); serial verb constructions (Ch. 11); sentence formation and nominalizations (Ch. 12); stylistic features of Amazonian languages, including numeral systems, speech styles, male and female speech, and mixed languages (Ch. 13); and, finally, a summary called the ‘treasures of Amazonian languages’ (Ch. 14). The book is written using the ‘fundamental typological theoretical apparatus’ of basic linguistic theory (xvi). Each of the chapters contains carefully chosen examples to illustrate the relevant topics. Although it is understandable that choices have to be made while writing a book of this kind, there does seem to be some unevenness in the area covered in that several features found in the Guianas and northwestern Amazonia but less so elsewhere are not included. One example is implosive [End Page 529] consonants (not found in the subject index), which are only mentioned on p. 108 (Ch. 3) in regard to older speakers of Mamaind...

Ficus insipida subsp. insipida (Moraceae) reveals the role of ecology in the phylogeography of widespread Neotropical rain forest tree species.

AimTo examine the phylogeography of Ficus insipida subsp. insipida in order to investigate patterns of spatial genetic structure across the Neotropics and within Amazonia.LocationNeotropics.MethodsPlastid DNA (trnH–psbA; 410 individuals from 54 populations) and nuclear ribosomal internal transcribed spacer (ITS; 85 individuals from 27 populations) sequences were sampled from Mexico to Bolivia, representing the full extent of the taxon's distribution. Divergence of plastid lineages was dated using a Bayesian coalescent approach. Genetic diversity was assessed with indices of haplotype and nucleotide diversities, and genetic structure was examined using spatial analysis of molecular variance (SAMOVA) and haplotype networks. Population expansion within Amazonia was tested using neutrality and mismatch distribution tests.ResultstrnH–psbA sequences yielded 19 haplotypes restricted to either Mesoamerica or Amazonia; six haplotypes were found among ITS sequences. Diversification of the plastid DNA haplotypes began c. 14.6 Ma. Haplotype diversity for trnH–psbA was higher in Amazonia. Seven genetically differentiated SAMOVA groups were described for trnH–psbA, of which two were also supported by the presence of unique ITS sequences. Population expansion was suggested for both markers for the SAMOVA group that contains most Amazonian populations.Main conclusionsOur results show marked population genetic structure in F. insipida between Mesoamerica and Amazonia, implying that the Andes and seasonally dry areas of northern South America are eco-climatic barriers to its migration. This pattern is shared with other widespread pioneer species affiliated to wet habitats, indicating that the ecological characteristics of species may impact upon large-scale phylogeography. Ficus insipida also shows genetic structure in north-western Amazonia potentially related to pre-Pleistocene historical events. In contrast, evident population expansion elsewhere in Amazonia, in particular the presence of genetically uniform populations across the south-west, indicate recent colonization. Our findings are consistent with palaeoecological data that suggest recent post-glacial expansion of Amazonian forests in the south.

Demand for beef is unrelated to pasture expansion in northwestern Amazonia

For decades, pastures have replaced Amazon forests, threatening biodiversity. Two dominant hypotheses explain this process. First, according to the hamburger connection beef markets promote conversion of forests into cattle ranches resulting in deforestation. Second, the land-as-wealth hypothesis explains deforestation as the result of land appreciation in forest frontiers. We tested these hypotheses using land use and socioeconomic data from northwestern Amazonia from 2000 to 2009. We also investigated two key control variables: coca cultivation and eradication, both of which have been proposed as important drivers of forest loss. We found high rate of conversion from forest to pasture, and unimpeded forest fragmentation. As predicted by the hamburger connection, pastures expanded as the cattle inventory grew. Beef demand did not drive pasture expansion, as ranching revenues declined and beef prices were roughly stable. Coca cultivation did not respond to the eradication campaign, and declined as the population became increasingly urbanized. We propose that investment on roads has enhanced the anticipated value of land. Cattle bolster land claims and can be used as financial collateral, so they have inherent value even without market exchange. Cattle can then increase despite stable beef prices and declining ranching revenues. To protect biodiversity, policy interventions that enhance the value of standing forests are needed to slow deforestation and fragmentation in these rapidly changing landscapes.

Hydroclimate variability of the northwestern Amazon Basin near the Andean foothills of Peru related to the South American Monsoon System during the last 1600 years

Hydroclimate variability of the northwestern Amazon Basin near the Andean foothills of Peru related to the South American Monsoon System during the last 1600 years

Two Contrasting Severe Seasonal Extremes in Tropical South America in 2012: Flood in Amazonia and Drought in Northeast Brazil

AbstractTwo simultaneous extreme events affected tropical South America to the east of the Andes during the austral summer and fall of 2012: a severe drought in Northeast Brazil and intense rainfall and floods in Amazonia, both considered records for the last 50 years. Changes in atmospheric circulation and rainfall were consistent with the notion of an active role of colder-than-normal surface waters in the equatorial Pacific, with above-normal upward motion and rainfall in western Amazonia and increased subsidence over Northeast Brazil. Atmospheric circulation and soil moisture anomalies in the region contributed to an intensified transport of Atlantic moisture into the western part of Amazonia then turning southward to the southern Amazonia region, where the Chaco low was intensified. This was favored by the intensification of subtropical high pressure over the region, associated with an anomalously intense and northward-displaced Atlantic high over a relatively colder subtropical South Atlantic Ocean. This pattern observed in 2012 was not found during other wet years in Amazonia such as 1989, 1999, and 2009. This suggests La Niña as the main cause of the abundant rainfall in western Amazonia from October to December, with wet conditions starting earlier and remaining until March 2012, mostly in northwestern Amazonia. The anomalously high river levels during the following May–July were a consequence of this early and abundant rainy season during the previous summer. In Northeast Brazil, dry conditions started to appear in December 2011 in the northern sector and then extended to the entire region by the peak of the rainy season of February–May 2012.

The Major Floods in the Amazonas River and Tributaries (Western Amazon Basin) during the 1970–2012 Period: A Focus on the 2012 Flood*

AbstractIn this work, the authors analyze the origin of the extreme floods in the Peruvian Amazonas River during the 1970–2012 period, focusing on the recent April 2012 flooding (55 400 m3 s−1). Several hydrological variables, such as rainfall, terrestrial water storage, and discharge, point out that the unprecedented 2012 flood is mainly related to an early and abundant wet season over the north of the basin. Thus, the peak of the Marañón River, the northern contributor of the Amazonas, occurred sooner than usual (in April instead of May), coinciding with the peak of the Ucayali River, the southern contributor. This concomitance caused a dramatic flood downstream in the Peruvian Amazonas. These results are compared to the amplitude and timing of the three most severe extreme floods (1970–2011). The analysis of the climatic features related to the most important floods (1986, 1993, 1999, and 2012) suggests that they are characterized by a La Niña event, which originates a geopotential height wave train near the ground, with positive anomalies over the subtropical South and North Pacific and Atlantic and over southeastern South America. These patterns contribute to 1) the origin of an abundant humidity transport flux from the tropical North Atlantic and the Caribbean Sea toward the northwestern Amazon and 2) the maintenance of the monsoon flux over this region. They both favor a strong convergence of humidity in the northern Amazonas basin. Finally, the authors suggest that the intensity of floods is more likely related to an early La Niña event (as observed during the 2011/12 season), early rainfall, and simultaneous peaks of both tributaries of the Amazonas River.

The role of groundwater in the Amazon water cycle: 3. Influence on terrestrial water storage computations and comparison with GRACE

AbstractWe explore the mechanisms whereby groundwater influences terrestrial water storage (TWS) in the Amazon using GRACE observations and two contrasting versions of the LEAF‐Hydro‐Flood hydrological model: one with and the other without an interactive groundwater. We find that, first, where the water table is shallow as in northwestern Amazonia and floodplains elsewhere, subsurface stores (vadose zone and groundwater) are nearly saturated year‐round, hence river and flooding dominate TWS variation; where the water table is deep as in southeastern Amazonia, the large subsurface storage capacity holds the infiltrated water longer before releasing it to streams, hence the subsurface storage dominates TWS variation. Second, over the whole Amazon, the subsurface water contribution far exceeds surface water contribution to total TWS variations. Based on LEAF‐Hydro‐Flood simulations, 71% of TWS change is from subsurface water, 24% from flood water, and 5% from water in river channels. Third, the subsurface store includes two competing terms, soil water in the vadose zone and groundwater below the water table. As the water table rises, the length of vadose zone is shortened and hence the change in groundwater store is accompanied by an opposite change in soil water store resulting in their opposite phase and contributions to total TWS. We conclude that the inclusion of a prognostic groundwater store and its interactions with the vadose zone, rivers, and floodplains in hydrological simulations enhances seasonal amplitudes and delays seasonal peaks of TWS anomaly, leading to an improved agreement with GRACE observations.

Viviendo en el bosque. Un Siglo de investigaciones sobre los makú del Noroeste amazónico by Gabriel Cabrera Becerra (review)

Reviewed by: Viviendo en el bosque. Un Siglo de investigaciones sobre los makú del Noroeste amazónico by Gabriel Cabrera Becerra Bartholomew Dean Gabriel Cabrera Becerra, ed., Viviendo en el bosque. Un Siglo de investigaciones sobre los makú del Noroeste amazónico. Medellin: Universidad Nacional de Colombia, Facultad de Ciencias Humanas y Económicas, 2010. 245 pp. Gabriel Cabrera Becerra’s edited collection Viviendo en el Bosque (Living in the Forest) is a collection of essays devoted to understanding the multiple, small-scale “hunter-gatherer” societies known collectively in the ethnographic literature by the ethnonym Maku. The issue of Maku identity is a complex topic complicated by the fact that many native “mobile” peoples in northwestern Amazonia have at one time or another been called Maku: including the Nükâk and the Kákwâ (Bara Cacua or Makú) of Colombia; the Hupdë and the Yuhupdë of Brazil and Colombia; and the Nadëb (Kabori) and the Düw (Dâw o Kamâ) of Brazil. In the northern border frontier between the Colombian and Brazilian Amazon, two culturally distinctive, yet inter-dependent indigenous social groupings reside: the sedentary Eastern Tukano and Arawak speaking societies and the nomadic Maku peoples. But when it comes to describing the contemporary social topography of the region it would certainly be misleading only to emphasize the dynamics of intra-ethnic indigenous relations and say nothing about the broader supra-local context, namely the presence of outsiders who are increasingly trying to gain a foothold in Maku territories. In the Colombian Amazon, the fight for indigenous people’s cultural survival remains fierce, while the politics of land claims and indigeneity are volatile. Recent governmental restrictions on indigenous societies like the Nükâk Maku threaten the very basis of their cultural autonomy, not to mention their customary livelihoods, which were predicated on foraging and hunting and gathering the forests and waterways they once called their home. Indeed, a mere generation ago, nomadic groups such as the [End Page 309] Nükâk Maku enjoyed a more or less serene life, largely removed from the so-called modern world of global markets, digital-interconnections, intrusive Spanish-based formal education, and the impersonal dictates of capitalist production. Instead, these proud nomadic peoples spent their time with one another leisurely trekking through a swath of the northwest Amazon rain forest roughly three times the size of Los Angeles. But this was all to change abruptly and irrevocably following sustained contact with national Colombian society beginning in the 1980s. Today, the Nükâk Maku have been forced from their territorial home-lands by a confluence of factors, like the growth of an illicit coca economy, and the presence of external social actors—leftist rebels, (including the Revolutionary Armed Forces of Colombia, or FARC), paramilitary death-squads, and State security forces. For their part, the Nükâk Maku peoples seem now to be a shadow of their former selves. They currently inhabit an unkempt clearing only half the size of a soccer field near the Colombian settlement of San José del Guaviare. Nevertheless, local indigenous Maku leaders continue to clamor for the expulsion of the military and leftist rebels from their homelands; recently Colombia’s Constitutional Court declared that the armed forces must vacate the Nükâk’s territory, which is currently employed as a major training base by Colombian special forces and navy infantry. Spanning more than a century of keen ethnographic description, Gabriel Cabrera Becerra’s welcome edited collection brings together texts devoted to assessing various aspects of Maku society and history. Comprised of contributions from a number of complementary disciplinary approaches, including anthropology, linguistics, and history, it grapples with a series of key issues, like territoriality, ethnographic film, childhood, inter-cultural education, and spatial location. A series of poorly understood themes in lowland ethnology are developed, such as the nature of the Maku’s division of labor, the dynamic forces shaping their settlement patterns, and their controversial formalized relations of subservience vis-à-vis other indigenous and mestizo or caboclo societies. A condensed Spanish translation of Theodor Koch-Grünberg’s (1906) classic essay on the Maku peoples is reprinted in the collection.1 Written during...

How much effort should be employed for surveying a low-diversity Amazonian mammal assemblage using line-transects?

Line-transect surveys are commonly used for sampling large mammals, but estimates of the effort needed to reliably surveying low-diversity assemblages of mammals are scarce. Using data from line-transects and species accumulation curves, I examined whether or not a sampling effort previously suggested to survey mammals elsewhere (ca. 85-100 km) would be satisfactory for surveying a low-diversity assemblage of large mammals in the Rio Negro basin in northern Amazonia. In total, 14 mammals were recorded after an accumulated effort of 690 km walked. The desired threshold of completeness was only achieved in one of six transects after an average effort of 115 km surveyed. Considering the entire landscape (all transects pooled), survey completeness was reached after a much higher effort. Moreover, the theoretical effort required to achieve completeness was estimated to be 150-360 km per transect, and 512 km for the landscape. Further studies are required to fully understand this issue, but meanwhile it is safest to assume that higher sampling efforts should be employed when surveying low-diversity assemblages through diurnal line-transects in northwestern Amazonia to get robust estimates of mammal richness.

Landscape Dynamics in Northwestern Amazonia: An Assessment of Pastures, Fire and Illicit Crops as Drivers of Tropical Deforestation

Many studies have identified drivers of deforestation throughout the tropics and, in most cases, have recognised differences in the level of threat. However, only a few have also looked at the temporal and spatial dynamics by which those drivers act, which is critical for assessing the conservation of biodiversity as well as for landscape planning. In this study, we analyse land cover change between 2000 and 2009 in north-western Colombian Amazonia to identify the interactions between the use of fire, cultivation of illicit crops and establishment of pastures, and their impacts on the loss of forest in the region. Yearly analyses were undertaken at randomly selected sample areas to quantify the average areas of transition of land cover types under different landscape compositions: forest-dominated mosaics, pasture mosaics, fire mosaics, and illicit crop mosaics. Our results indicate that despite the fact that forest areas were well-preserved, deforestation occurred at a low annual rate (0.06%). Conversion to pasture was the main factor responsible for forest loss (the area of pastures tripled within forest mosaics over 8 years), and this process was independent of the landscape matrix in which the forests were located. In fire mosaics, burning is a common tool for forest clearing and conversion to pasture. Thus, forests in fire mosaics were highly disturbed and frequently transformed from primary to secondary forests. The use of fire for illicit cropping was not detected, partly due to the small size of common illicit crops. Forest regeneration from pastures and secondary vegetation was observed in areas with large amounts of natural forest. Overall, assuming the continuation of the observed pasture conversion trend and the use of forest fire, we suggest that our results should be incorporated into a spatially explicit and integrated decision support tool to target and focus land-planning activities and policies.

Use of Landsat and SRTM Data to Detect Broad-Scale Biodiversity Patterns in Northwestern Amazonia

Vegetation maps are the starting point for the design of protected areas and regional conservation plans. Accurate vegetation maps are missing for much of Amazonia, preventing the development of effective and compelling conservation strategies. Here we used a network of 160 inventories across northwestern Amazonia to evaluate the use of Landsat and Shuttle Radar Topography Mission (SRTM) data to identify floristic and edaphic patterns in Amazonian forests. We first calculated the strength of the relationship between these remotely-sensed data, and edaphic and floristic patterns in these forests, and asked how sensitive these results are to image processing and enhancement. We additionally asked if SRTM data can be used to model patterns in plant species composition in our study areas. We find that variations in Landsat and SRTM data are strongly correlated with variations in soils and plant species composition, and that these patterns can be mapped solely on the basis of SRTM data over limited areas. Using these data, we furthermore identified widespread patch-matrix floristic patterns across northwestern Amazonia, with implications for conservation planning and study. Our findings provide further evidence that Landsat and SRTM data can provide a cost-effective means for mapping these forests, and we recommend that maps generated from a combination of remotely-sensed and field data be used as the basis for conservation prioritization and planning in these vast and remote forests.

Dynamics, patterns and causes of fires in Northwestern Amazonia.

According to recent studies, two widespread droughts occurred in the Amazon basin, one during 2005 and one during 2010. The drought increased the prevalence of climate-driven fires over most of the basin. Given the importance of human-atmosphere-vegetation interactions in tropical rainforests, these events have generated concerns over the vulnerability of this area to climate change. This paper focuses on one of the wettest areas of the basin, Northwestern Amazonia, where the interactions between the climate and fires are much weaker and where little is known about the anthropogenic drivers of fires. We have assessed the response of fires to climate over a ten-year period, and analysed the socio-economic and demographic determinants of fire occurrence. The patterns of fires and climate and their linkages in Northwestern Amazonia differ from the enhanced fire response to climate variation observed in the rest of Amazonia. The highest number of recorded fires in Northwestern Amazonia occurred in 2004 and 2007, and this did not coincide with the periods of extreme drought experienced in Amazonia in 2005 and 2010. Rather, during those years, Northwestern Amazonia experienced a relatively small numbers of fire hotspots. We have shown that fire occurrence correlated well with deforestation and was determined by anthropogenic drivers, mainly small-scale agriculture, cattle ranching (i.e., pastures) and active agricultural frontiers (including illegal crops). Thus, the particular climatic conditions for air convergence and rainfall created by proximity to the Andes, coupled with the presence of one of the most active colonisation fronts in the region, make this region differently affected by the general drought-induced fire patterns experienced by the rest of the Amazon. Moreover, the results suggest that, even in this wet region, humans are able to modify the frequency of fires and impact these historically well preserved forests.

Morphometric and molecular differentiation of a Rhodnius robustus-like form from R. robustus Larousse, 1927 and R. prolixus Stal, 1859 (Hemiptera, Reduviidae)

In Triatominae, “robustus” group constitutes a cluster of species with great haplotypic divergences but high similarities at morphological and nuclear DNA levels. Given these similarities, species identification generates a frequently problematic issue. In northwestern Amazonia, Rhodnius robustus cohabit with an apparently new species, cryptic with R. robustus (Abad-Franch and Monteiro, 2005). In this region (municipality of Puerto Asís, Department of Putumayo, Colombia), we collected insects classified as R. robustus by traditional keys. We compared this sample with specimens of R. robustus from Venezuela, and of R. prolixus from Colombia and Venezuela. The comparisons used landmark-based geometric morphometrics, and analyses of mitochondrial cytochrome b gene and of D2 variable region of the 28S RNA. The shape of the wings from Puerto Asís specimens disclosed clear-cut divergence from the shape of the wings as found for R. prolixus specimens from Venezuela and Colombia, and diverged from the shape of R. robustus from Venezuela. Thus, morphometric analyses suggested that the Puerto Asís collection could represent a new taxon. Using R. pallescens as an outgroup, a tentative phylogenetic tree based on the geometry of the wing showed the Rhodnius from Puerto Asís more similar to the R. prolixus from Colombia than their congeners from Venezuela. In contrast, the molecular classification clustered Colombian R. prolixus and Venezuelan R. robustus with published GenBank sequences, but it gave the insects from Puerto Asís a basal position to the “robustus” group. This outcome suggests that the Puerto Asís haplotype could be the one found by Abad-Franch and Monteiro (2005). Thus, both morphometric and molecular markers used here, although differing in the phylogenetic classification of samples, could differentiate the Puerto Asís sample from the morphologically similar R. prolixus and R. robustus. This could represent a valuable help in the entomological surveillance related to the control of Chagas disease in the South of Colombia and North of Ecuador.

Simulating fire regimes in the Amazon in response to climate change and deforestation

Fires in tropical forests release globally significant amounts of carbon to the atmosphere and may increase in importance as a result of climate change. Despite the striking impacts of fire on tropical ecosystems, the paucity of robust spatial models of forest fire still hampers our ability to simulate tropical forest fire regimes today and in the future. Here we present a probabilistic model of human-induced fire occurrence for the Amazon that integrates the effects of a series of anthropogenic factors with climatic conditions described by vapor pressure deficit. The model was calibrated using NOAA-12 night satellite hot pixels for 2003 and validated for the years 2002, 2004, and 2005. Assessment of the fire risk map yielded fitness values > 85% for all months from 2002 to 2005. Simulated fires exhibited high overlap with NOAA-12 hot pixels regarding both spatial and temporal distributions, showing a spatial fit of 50% within a radius of 11 km and a maximum yearly frequency deviation of 15%. We applied this model to simulate fire regimes in the Amazon until 2050 using IPCC's A2 scenario climate data from the Hadley Centre model and a business-as-usual (BAU) scenario of deforestation and road expansion from SimAmazonia. Results show that the combination of these scenarios may double forest fire occurrence outside protected areas (PAs) in years of extreme drought, expanding the risk of fire even to the northwestern Amazon by midcentury. In particular, forest fires may increase substantially across southern and southwestern Amazon, especially along the highways slated for paving and in agricultural zones. Committed emissions from Amazon forest fires and deforestation under a scenario of global warming and uncurbed deforestation may amount to 21 +/- 4 Pg of carbon by 2050. BAU deforestation may increase fires occurrence outside PAs by 19% over the next four decades, while climate change alone may account for a 12% increase. In turn, the combination of climate change and deforestation would boost fire occurrence outside PAs by half during this period. Our modeling results, therefore, confirm the synergy between the two Ds of REDD (Reducing Emissions from Deforestation and Forest Degradation in Developing Countries).

Extreme climatic events in the Amazon basin

During 2009 the Amazon basin was hit by a heavy flooding with a magnitude and duration few times observed in several decades. Torrential rain in northern and eastern Amazonia during the austral summer of 2008–2009 swelled the Amazon River and its tributaries. By July 2009, water levels of the Rio Negro, a major Amazon tributary, reached at Manaus harbor a new record, the highest mark of the last 107 years. During the 2008–2009 hydrological year, the rainy season on northern and northwestern Amazonia started prematurely, and was followed by a longer-than-normal rainy season. An anomalously southward migration of the ITCZ during May–June 2009, due to the warmer than normal surface waters in the tropical South Atlantic, was responsible for abundant rainfall in large regions of eastern Amazonia and Northeast Brazil from May to July 2009. We also compared the flood of 2009 with other major events recorded in 1989 and 1999. The hydrological consequences of this pattern were earlier than normal floods in Amazon northern tributaries, which peak discharges at their confluences with the main stem almost coincided with the peaks of southern tributaries. Since the time displacement of the contribution to the main stem of northern and southern Amazon tributaries is fundamental for damping flood waves in the main stem, the simultaneous combinations of peak discharges of tributaries resulted in an extreme flood.

Impact of Leaf Harvest on Populations of Lepidocaryum tenue, an Amazonian Understory Palm Used for Thatching

Leaves of the palm Lepidocaryum tenue are one of the most prized thatching materials in northwestern Amazonia. We studied the population dynamics of this stoloniferous palm in Colombian Amazonia, using ramet-based Lefkovitch matrices, and assessed the impact of leaf harvest on population structure and dynamics, through experimental defoliation. Leaf production rate of unharvested palms ranged between 0.93 leaves per year in seedlings and 1.71 in adults. Vegetative shoots produced through stolons are more important than seedlings for maintaining the population; stolons act also as a reserve to overcome damage in the population. The potential population growth rate was 8.3 % per year (λ = 1.083). Juveniles had the highest contribution to population growth, and permanence was the most important life parameter. Thus, harvest of leaves for thatching can jeopardize the population if juveniles are also harvested. An initial harvest intensity of more than 50% of the leaves in a crown, or leaving the palm with fewer than four leaves, would have a negative impact on leaf production. Although matrix modeling suggests that all adult ramets can be harvested, this must be taken with caution, as clonal integration may play an important role in population dynamics. Long-term harvest of Lepidocaryum leaves is possible, if plots are harvested in turns of four years, thus allowing palms to recover from the previous harvest. A better control on the quality of the braided tiles sold in the market would also ensure their longer duration, thus reducing the pressure on the resource.

The Threats from Oil Spills: Now, Then, and in the Future

The ongoing oil spill from the blown-out well by the name of Macondo, drilled by the ill-fated rig Deepwater Horizon, has many features in common with another blowout in the Mexican Gulf that happened three decades ago. Then the oil gushed out from the Ixtoc I well drilled by the Sedco 135-F semi-submersible rig. In the years between these catastrophes, the source and nature of oil spills have undergone large changes. Huge spills from tankers that ran aground or collided used to be what caught the headlines and caused large ecological damage. The number and size of such accidental spills have decreased significantly. Instead, spills from ageing, ill-maintained or sabotaged pipelines have increased, and places like Arctic Russia, the Niger Delta, and the northwestern Amazon have become sites of reoccurring oil pollution. As for blowouts, there is no clear trend with regard to the number of incidences or amounts of spilled oil, but deepwater blowouts are much harder to cap and thus tend to go on longer and result in the release of larger quantities of oil. Also, oil exploration and extraction is moving into ever-deeper water and into stormier and icier seas, increasing potential risks. The risk for reoccurring spills like the two huge Mexican Gulf ones is eminent and must be reduced.

Fruit Preferences of Ateles belzebuth in Tinigua Park, Northwestern Amazonia

Spider monkeys are known to be highly frugivorous, relying on a great diversity of ripe fruits. However, there is controversy regarding their classification as specialized frugivores that choose certain types of fruits, e.g., lipid-rich fruits, or generalist frugivores, because they tend to consume the most available fleshy fruits in the environment. We combined data on fruit morphology, phenology, and demographic information for 202 plant species with nutritional information for 78 species, to assess feeding preferences of free ranging white-bellied spider monkeys (Ateles belzebuth) over 2 yr in Tinigua National Park, Colombia. We used simple and multiple regression analyses to predict fruit feeding time and preference, quantified via behavioral follows of focal individuals (1567 h). Spider monkeys spent more time consuming fruits from productive and abundant plants. These variables had the highest explanatory power, but predicted only 22% of variation in feeding times. Fruit preference was also positively associated with diameter-at-breast height (DBH) and negatively associated with the consumption of species producing mainly in periods of fruit scarcity. Spider monkeys consumed both sugar-rich, e.g., Gustavia hexapetala, and lipid-rich, e.g., Oenocarpus spp., fruits more than predicted from their abundance. Overall, the results show that, at Tinigua Park, spider monkeys are generalized frugivores, as they mainly consume productive species, and do not specialize on lipid-rich fruits. Large data sets are necessary for a good description of primate diets when they inhabit diverse tropical forests; nonetheless it is difficult to find variables that explain a large proportion of the variation in feeding times, because dozens of species are included in the annual diet and exceptions will always occur in relation to preferred plant traits.

Multi-scale comparisons of tree composition in Amazonian terra firme forests

Abstract. We explored the floristic composition of terra firme forests across Amazonia using 55 plots. Firstly, we examined the floristic patterns using both genus- and species-level data and found that the species-level analysis more clearly distinguishes among forests. Next, we compared the variation in plot floristic composition at regional- and continental-scales, and found that average among-pair floristic similarity and its decay with distance behave similarly at regional- and continental-scales. Nevertheless, geographical distance had different effects on floristic similarity within regions at distances <100 km, where north-western and south-western Amazonian regions showed greater floristic variation than plots of central and eastern Amazonia. Finally, we quantified the role of environmental factors and geographical distance for determining variation in floristic composition. A partial Mantel test indicated that while geographical distance appeared to be more important at continental scales, soil fertility was crucial at regional scales within western Amazonia, where areas with similar soil conditions were more likely to share a high number of species. Overall, these results suggest that regional-scale variation in floristic composition can rival continental-scale differences within Amazonian terra firme forests, and that variation in floristic composition at both scales is influenced by geographical distance and environmental factors, such as climate and soil fertility. To fully account for regional-scale variation in continental studies of floristic composition, future floristic studies should focus on forest types poorly represented at regional scales in current datasets, such as terra firme forests with high soil fertility in north-western Amazonia.