Amazonian Land Research Articles

Amazonian conservation across archipelagos of Indigenous territories.

Indigenous stewardship is essential to the conservation of biocultural diversity, yet conventional conservation models often treat Indigenous territories (ITs) as homogeneous or isolated units. We propose that archipelagos of Indigenous territories (AITs), clusters of ITs that span geographies but are connected through shared cultural or political ties maintained by Indigenous nations, are crucial for understanding and enhancing conservation strategies that recognize the complexity of Indigenous stewardship. We classified 3572 ITs in the Amazon into 4 categories-single or multiple nations with either singular IT or AIT-to assess their spatial heterogeneity, governance, and conservation potential. We then assessed species richness, carbon stocks, and pressures across these different categories. To examine how AITs can enhance biocultural conservation efforts, we conducted a case study of the Cofán Nation in Ecuador. AITs covered 45% of the Amazonian land area and had higher species richness and carbon stocks than single IT configurations. However, AITs faced greater pressures from development and extractive activities. In the case study, the Cofán AIT was shaped by colonization and land titling challenges, but their community-driven governance, cross-territorial collaboration, and adaptive responses-such as comanagement agreements and resisting extractive activities-enhanced their ecological and cultural resilience amid growing development pressures. Our findings suggest that AITs facilitate the exchange of resources, knowledge, and cultural practices, which strengthens social connectivity, reinforces governance structures, and enables adaptive management across ITs, thereby enhancing biocultural resilience across discontinuous spaces. This work advocates for a paradigm shift in conservation planning and practice that recognizes the vital role of AITs in sustaining Amazonian ecosystems and Indigenous lifeways, particularly in the face of increasing pressures.

History and architectural characteristics of the iron bandstands in Belém, Pará

From the late 19th to the beginning of the 20th century, Belém underwent a comprehensive urban and architectural renovation in Pará, northern Brazil. The transformations in these Amazonian lands, the rubber cycle’s outcomes, included the construction and renovation of squares which were remarkably equipped with prefabricated iron bandstands imported from diverse European countries. Several buildings have remained in the city’s landscape but have been little researched and documented. Meanwhile, they suffer from weathering (mostly corrosion) and inappropriate anthropic actions allied to the absence of proper maintenance, gradually losing their features and pieces. As these facts are a significant challenge to their conservation, this paper aims to document Belém’s eight remaining iron bandstands by investigating their historical trajectories and architectural characteristics as preservation subsidies. The methodological approach was divided into two phases: 1) historical and iconographic study; 2) architectural documentation and analysis. The research’s products consisted of two-dimensional drawings, registration forms, and a comparative analysis of the buildings assembled within Belém’s historical centre. The process allowed the detailing of their backgrounds, origins, and dating. It produced consistent graphic documentation whose interpretation highlighted various architectural and technical solutions due to the uniqueness of each structure. This data advances the knowledge about this kind of building in heritage conservation and construction history, grounding the conclusion that industrialization processes do not define them as homogenous structures.

Prospective analysis of deforestation determinants in the Amazonian landscapes

Amazonian landscapes are socio-ecological systems that provide fundamental ecosystem services for the maintenance of landscape regulation, biodiversity, and climate regulation. The increasing pressure of population density, productive activities over natural resources, infrastructure development, timber exploitation, and illicit crops among other determinants have put Amazonian landscapes at risk due to deforestation. This research work aims to understand the possible interactions of the determinants of Amazonian deforestation and to describe its complex behavior with the socio-ecological systems with a supporting vision for future studies. Initially, a rigorous analysis the of literature review on the determinants of deforestation in the Amazon was made to be carried out a systemic representation based on the dynamics of systems methodology on the behavioral interactions between these different determinants. The determinants of deforestation can be classified into determinants by activity, by support, by social dynamism, and by political pressure, which converge in these natural areas of the Amazonian landscape and transform into an urban-agricultural area, this change in the coverage of Amazonian land use generating rate environmental problems both locally and globally. By analyzing the causal relationships of the determinants of Amazon deforestation in the different scenarios, the proposed hypothesis is that with the large-scale increase of productive activities on natural resources, the Amazonian landscapes will not be sustainable in urban-agricultural environments. Finally, this research found that Amazon can confront different scenarios with diverse futures subject to the socio-ecological actions generated for the conservation and relevance of its ecosystem services.

Seizing resilience windows to foster passive recovery in the forest-water interface in Amazonian lands

Forest regeneration has increased in many tropical abandoned lands and current restoration commitments in this region aim to restore over 1,400,000 km2 of degraded land by 2030. Although regenerating forests recover biomass, biodiversity, and processes with time, the recovery trajectories may be uncertain due to past disturbances. Currently, there is a lack of knowledge to sustain the effectiveness of passive regeneration for the recovery of riparian forests and the adjacent waterbodies in the tropics, which may compromise the outcomes of ongoing and future tropical riparian restoration programs. We evaluated the drivers of riparian forest structural recovery and how this relates to stream conditions in 12 abandoned pasturelands in eastern Brazilian Amazonia. These pasturelands range across regeneration age (pasture (PA) — 0 to 4 years; young regeneration (YR) — 8 to 12 years; old regeneration (OR) — 18 to 22 years) and years of past land-use (PA — 23.25 average years of past land-use, YR — 18.25, OR — 7). We compared the conditions of these sites to 4 reference sites with conserved forests (REF, >100 years), where there was no recorded pasture use in the past. Short-term responses of forests and streams to passive regeneration indicated high ecosystem resilience after low to intermediate past land-use intensity, reflected in the improvement of stream ecosystems. Such high resilience is possibly attributable to low- to intermediate-intensity pasture-related disturbances, remaining forest matrix, and residual structures (e.g. roots, sprouts, and in-stream wood) observed in the area. Our results suggest a recovery by 12 to 20 years for riparian forests of this region. However, areas degraded by intensive land-use apparently showed delayed recovery. We conclude that seizing resilience windows (defined here as the period when ecosystems retain high potential resilience) is essential to foster passive recovery of riparian forests and streams more cost-effectively in the tropics.

Constraining Amazonian land surface temperature sensitivity to precipitation and the probability of forest dieback

The complete or partial collapse of the forests of Amazonia is consistently named as one of the top ten possible tipping points of Planet Earth in a changing climate. However, apart from a few observational studies that showed increased mortality after the severe droughts of 2005 and 2010, the evidence for such collapse depends primarily on modelling. Such studies are notoriously deficient at predicting the rainfall in the Amazon basin and how the vegetation interacts with the rainfall is poorly represented. Here, we use long-term surface-based observations of the air temperature and rainfall in Amazonia to provide a constraint on the modelled sensitivity of temperature to changes in precipitation. This emergent constraint also allows us to significantly constrain the likelihood of a forest collapse or dieback. We conclude that Amazon dieback under IPCC scenario RCP8.5 (crossing the tipping point) is not likely to occur in the twenty-first century.

A global production network for ecosystem services: The emergent governance of landscape restoration in the Brazilian Amazon

Over the last few decades, numerous initiatives have advanced forest landscape restoration in the Amazon, and in 2015 the Brazilian government set an ambitious, still-valid, target to restore 4.8 million hectares of degraded Amazonian land by 2030. This has contributed to an emergent global restoration network that connects multiple stakeholders and processes for funding, implementing and monitoring restoration actions in such a way that prepares various ecosystem services for market integration. The network arose in tandem with the evolution of an institutional framework that includes regulatory requirements within Brazil, global commitments linked to climate change mitigation, corporate sustainability strategies, and the growth of crowd-sourcing activism. This paper presents restoration activities as embedded within a Global Production Network (GPN) for an ecosystem service, which we use as a heuristic device to inform our understanding of emergent environmental governance structures. The resulting multi-scalar, networked mode of environmental governance is presented as a web-like structure co-created by institutional evolution, actor-specific strategies, and interactions between firms and non-firm actors. The article pays particular attention to a case study of how the restoration network manifests territorially in the Upper Xingu region of the Brazilian Amazon. Despite the strong North-South orientation of dominant funding relationships, network governance is also seen to be relational. This is evident from the dissemination of ideas, supply models and seeding techniques from Upper Xingu to other regions of Brazil. These insights could be applied to improve landscape restoration outcomes, and indeed the provisioning of ecosystem services more broadly.

Does amazonian land use display market failure? An opportunity-cost approach to the analysis of amazonian environmental services

The article discusses whether deforestation in the Amazonian region should be considered a typical case of market failure and computes the opportunity cost of economic activities that promote deforestation relative to uses that keep the forest intact. For environmental resources threatened by Amazon deforestation, forms of productive land use (“opportunity” uses) are considered in terms of the net benefit values of primary land-based activities. The accounting exercise conducted in this study calculates the net benefit per hectare obtained from the direct use value (DUV) for different land use alternatives (timber, non-timber, livestock and agriculture); the indirect use value (IUV) related to carbon storage; and the non-use value (NUV) (existence value). The results show that the opportunity cost of deforestation in 2009 was positive for the most common land use, livestock activity. Such findings indicate a market failure. Nonetheless, this is not the only possible outcome when considering alternative land uses.

Fish consumption on the Amazon: a review of biodiversity, hydropower and food security issues.

The lack of knowledge about the majority of fish species harvested in Amazonian small-scale fisheries, in association with impacts from hydroelectric power plants, may lead to biodiversity loss and a decrease in the protein food supply for riverine Amazonians. This study uses existing datasets on fisheries and riverine developmental projects to infer effects associated with fish losses where actual data and outcomes are not available. The targeted fish species' status may be regarded as either threatened or there being no knowledge of their conservation requirements, biology or ecology. Among the 90 Amazonian fish species that are the most important for the diet of the riverine fishers, 78% are not assessed or their biological information is unknown, according to the IUCN Red List. Consequently, the effects created by the thoroughly disregarded trade-off between energy generation and food security in the planning of Amazonian land use have been worsened by the lack of biological and ecological information on fish species.

Aerial and surface rivers: downwind impacts on water availability from land use changes in Amazonia

Abstract. The abundant evapotranspiration provided by the Amazon forests is an important component of the hydrological cycle, both regionally and globally. Since the last century, deforestation and expanding agricultural activities have been changing the ecosystem and its provision of moisture to the atmosphere. However, it remains uncertain how the ongoing land use change will influence rainfall, runoff, and water availability as findings from previous studies differ. Using moisture tracking experiments based on observational data, we provide a spatially detailed analysis recognizing potential teleconnection between source and sink regions of atmospheric moisture. We apply land use scenarios in upwind moisture sources and quantify the corresponding rainfall and runoff changes in downwind moisture sinks. We find spatially varying responses of water regimes to land use changes, which may explain the diverse results from previous studies. Parts of the Peruvian Amazon and western Bolivia are identified as the sink areas most sensitive to land use change in the Amazon and we highlight the current water stress by Amazonian land use change on these areas in terms of the water availability. Furthermore, we also identify the influential source areas where land use change may considerably reduce a given target sink's water reception (from our example of the Ucayali River basin outlet, rainfall by 5–12 % and runoff by 19–50 % according to scenarios). Sensitive sinks and influential sources are therefore suggested as hotspots for achieving sustainable land–water management.

Re-Legislating the Soil: Enclosure and Exception at the Amazon Frontiers

In 2009 a series of mobilizations articulated by indigenous groups took control over practically the entire Peruvian Amazon. Geographically distributed but politically articulated, these manifestations were fighting against the institution of a new Forest Law that would transform not only the juridical framework that governs Amazonian lands but potentially alter the very ecological nature of the forest itself. This text traces some of the lines of this conflict in order to discuss the relations between sovereignty and nature, government and environment, politics and ecology.

Mercado y medio ambiente: el caso de la soya en la Amazonía brasileña

The ongoing process of globalization increases competition between all countries in the international market. Competitiveness becomes the main challenge for commodities-producing regions without concern for social and environmental externalities. In the case of soy markets, Brazil initiated a process of Amazonian land occupation due to their favorable conditions for the growth of agribusiness extension. In addition to the great number of negative environmental consequences already registered, competitiveness is beginning to decline not only for the Amazonian region but also for surrounding agricultural areas.

Biodiversidad y endemismo de los caracoles terrestres Megalobulimus y Systrophia en la Amazonia occidental

In this work we performed a biogeographic study of two genera of Amazonian land snails, Megalobulimus (Strophocheilidae) and Systrophia (Scolodontidae). We used samples from different regions of the Peruvian Amazon, as well as bibliographic information. We analyzed both nuclear (5.8S-ITS2-28S rRNA) and mitochondrial (16S rRNA) genes to reconstruct phylogenies and obtain hypotheses concerning the evolutionary relationships among Amazonian genera and other species with global distribution. The nuclear phylogeny allowed us to determine the evolutionary position of both genera, and the mitochondrial phylogeny permitted the differentiation of species at the intrageneric level. We found that Megalobulimus clustered with the non-achatinoid clade within Stylommatophora, as expected, but its relationship to family Acavidae could not be demonstrated. Systrophia did not cluster with any of the two established clades, but formed a basal one within Stylommatophora. The mitochondrial gene 16S rRNA allowed us to differentiate Megalobulimus species, and performed well for DNA barcoding of these edible snails. Biogeographical analysis revealed several endemic species in the Peruvian Amazon within both genera, highlighting the Chanchamayo and Inambari biogeographic units.

Intraspecific divergence and DNA barcodes in Systrophia helicycloides (Gastropoda, Scolodontidae)

DNA barcoding analysis is based on the comparison of genetic distances to identify species using a segment of Cytochrome C Oxidase I (COI) gene. Species identification through DNA barcoding challenges problems in groups with high genetic diversity as molluscs. Thus, our aim was to estimate intraspecific divergence in the Amazonian land snail Systrophia helicycloides (Gastropoda, Scolodontidae) and evaluate the use of DNA barcoding in molecular identification of this land snail. Nucleotide sequences were compared with Genbank and BOLD (Barcode of Life Data Systems) databases. We conducted distance analyses using the Neighbour Joining method. Systrophia helicycloides showed two groups of haplotypes and intraspecific genetic distances higher than 4%. We observed an overlap between intraspecific and interspecific distances. The high divergence may be related to rapid mutation rate in the snail mitochondrial genome, to population distribution that influences genetic isolation and differentiation, and to ancestral DNA polymorphisms. COI profiles uploaded in BOLD are the first records of this species and can identify Systrophia helcycloides from other species. These profiles corroborated the high variation in the land snail genome. Therefore, species identification in this group needs a combined analysis of genetic distances, informative sites, and conventional taxonomy.

The Impact of Brazilian Biofuel Production on Amazônia

Global energy demand will increase through the twenty-first century. Competition for energy resources has already revealed geopolitical fault lines, and the dependence of industrial economies on fossil fuel promises to keep nations on edge. A widespread consensus has emerged that societies must transition to a new energy basis, given that fossil fuel is nonrenewable and its combustion leads to global warming. Although alternatives like nuclear energy and hydropower provide important electrical supplies locally, the search goes on, and recently much attention has focused on biofuel. Although biofuel represents a renewable and “green” energy, there is also a downside. This article considers one potential problem, namely, the impact of growing international biofuel demand on Amazônia. The article focuses on Brazil, given the explosive growth of Brazilian agriculture, and notable effects on forests within its national borders. The article seeks to answer this question: How will global demand for Brazil's land-based commodities, including biofuel, impact its tropical forest in the Amazon basin? In attempting to answer this question, the article describes recent agricultural expansion in Brazil and its emergent landscape of renewable energy. Using an adaptation of rent theory, it frames a concept of landscape cascade and shows how Brazil's expanding landscape of renewable energy is impacting forest areas at a great distance. The article then considers recent projections of demand for Amazonian land out to 2020, given growth of Brazilian biofuel production and cattle herds. The projections indicate that more Amazonian land will be demanded than has been made available by Brazilian environmental policy. With this result in mind, the article discusses the discursive dismemberment of Amazônia and how this articulates with efforts by Brazilian politicians to increase the region's land supply. The article points out that agricultural intensification holds the key to meeting global demand without degrading the Amazonian forest, a landscape unique in the world for its ecological and cultural riches.

Andean Cocaine: The Making of a Global Drug (review)

Reviewed by: Andean Cocaine: The Making of a Global Drug Monica Rankin Andean Cocaine: The Making of a Global Drug. By Paul Gootenberg. Chapel Hill: University of North Carolina Press, 2008. 464 pp. $65.00 (cloth); $24.95 (paper). From the coca fields of the Andean mountainsides to the laboratories of European chemists and eventually to the streets of U.S. cities, the history of cocaine has been long and complex. And until now the history of cocaine has been largely untold. In Andean Cocaine, Paul Gootenberg, relying on documentation from a panoply of diverse sources such as nineteenth-century medical journals, Amazonian land records, contemporary news accounts, and U.S. drug agency reports, crafts a narrative of cocaine that is firmly rooted in its Andean, and specifically Peruvian, origins. Using an approach that he calls the "new drug history," Gootenberg is helping to replace the conversation about the history of illicit drugs, previously dominated by medical and journalistic accounts, with a historical and interdisciplinary examination of drugs and drug usage. His monograph on the history of Andean cocaine joins the ranks of other recent studies of legal and illegal stimulants, such as tobacco, alcohol, chocolate, and opium, that place global commodities and products within a specific local context. Gootenberg argues that while many global influences have shaped the history of cocaine, the evolution of coca and cocaine products and policies must also be considered from an Andean, and specifically a Peruvian, context. Gootenberg identifies three "long arcs" or historical trajectories that help to define the history of cocaine. The first period marked cocaine's creation and the drug's emergence as a "good drug" or medical commodity from 1850 to the early twentieth century, when legal products containing cocaine became affordable, accessible, and popular throughout the Western world. He takes great care in differentiating between the local medicinal and ritualistic uses of the coca leaf in [End Page 566] Andean cultures and the chemically altered stimulant, cocaine. European travelers to South America took great interest in coca leaves in the early nineteenth century, and researchers began experimenting to uncover the secrets of the magical plant. After German scientist Albert Niemann successfully isolated the alkaloid of the coca plant responsible for its stimulant effect in 1860, a global commodity market skyrocketed for the new drug, cocaine. Gootenberg recounts the well-known histories of numerous Western stimulant concoctions of the late nineteenth century that contained various amounts of cocaine, such as Vin Mariani, Coca-Cola, and the patent medicines that claimed to cure a number of maladies from depression to indigestion to migraines and other pains. But Gootenberg also chronicles the local attempts of Peruvian elites to transform coca into both a nationalistic expression and a global commodity. The Peruvian national coca movement outlined in the first two chapters is part of larger historical processes that arose out of a push for national self-identification and modernization throughout South America in the late nineteenth century. Promoting cocaine as a "modernizing good," Peruvian leaders hoped to create a global market for cocaine products rivaling that of tea and coffee. During the second period, from the early twentieth century to the 1940s, the cocaine market declined as the United States pushed for greater regulation; cocaine itself eventually became a "pariah drug." The Peruvian-based commodity networks that had emerged in the late nineteenth century dwindled after 1910. Several factors contributed to a decline in the market for Andean cocaine, including new medicines that provided alternative anesthetics to cocaine and growing competition from coca producers in Japan and the Dutch colonies. But the most substantial challenge came from new anticocaine laws passed in the United States and eventually in other nations in the early decades of the twentieth century. While U.S. imports of Peruvian cocaine declined precipitously during that time, scientists and other leaders in Peru attempted to salvage the struggling industry. Gootenberg recounts the campaigns of Dr. Carlos Enrique Paz Soldán, who blamed global cocaine blockades on local "cocamanía." According to Paz Soldán, Peruvian Indians were descending into debauchery and ruin as they were left to consume the surplus of coca crops that had been marked for export in...

TROPICAL FOREST BIOMASS AND ITS RELATIONSHIP WITH P - BAND SAR DATA

The objective of this research is to show the potential of P-band polarimetric SAR images to define the space of
 attributes of primary and regenerating forest and also to estimate aerial biomass of such formations. The approach used
 was the analysis of the relation between backscatter and biomass data estimated by four specific allometric equations.
 The Bivariate Intensities HH-HV image was segmented and the mean s° of each segment was converted into biomass
 by the best fit function (the heat capacity model) and following that the biomass was mapped. As a conclusion, the best
 allometric equations for primary and secondary forest biomass estimation were defined, considering the different
 polarizations of P-band SAR data. The methodology used in this treatment of P-band data might improve the regional
 monitoring of Amazonian land cover change, a process whose speed was accelerated as a result of human action in the
 Amazon during the last two decades.

Effects of forest fragmentation on two sister genera of Amazonian rodents (Myoprocta acouchy and Dasyprocta leporina)

Because agoutis (Dasyprocta sp.) and acouchies (Myoprocta sp.) are the most important dispersers of several large-seeded Amazonian trees, knowing their responses to forest fragmentation is essential and urgent. But until now, there was no study showing their population trends in Amazonian land forest fragments. The present study was conducted at the Biological Dynamics of Forest Fragments Project, Central Amazon, Brazil. Eleven sites (three fragments of 1ha, three of 10ha, two of 100ha and three sites of continuous forest) were surveyed between 2003 and 2005. Agoutis and acouchies were systematically counted at each site through standard transect censuses and their densities were estimated with DISTANCE 4.1. Overall, I walked 100km, and encountered 136 acouchies and 35 agoutis. Fragmentation had a significant negative effect on acouchies and a significant positive effect on agouti densities. Acouchy density was 0.64±0.09 inds./ha (X¯±SE,N=3) in continuous forests and 0.07±0.07 inds./ha in 1-ha fragments. On the other hand, agouti density was 0.16±0.05 inds./ha in continuous forests and 0.71±0.24 inds./ha in 1-ha fragments. This study is consistent with the idea that in fragments, larger species of mammals are initially less affected by forest fragmentation than smaller ones. More critical to conservation is the fact that acouchies, which were negatively affected by fragmentation, are restricted to the core region of the Amazonian rainforests. Continued fragmentation of Amazonian forests should have vast negative consequences for the genus.

Litter fall and decomposition in primary, secondary and plantation forests in the Brazilian Amazon

Litter fall and leaf decomposition represent important functional processes, yet we have a limited understanding of these processes in disturbed and regenerating tropical habitats. Litter production, litterfall phenology and leaf decomposition were examined in primary forests, 14–19-year-old secondary forests and 4–5-year-old Eucalyptus urophylla plantations in the north-east Brazilian Amazon. Total annual litter fall was similar in primary and secondary forests, and lower in plantations. Leaf fall in primary and secondary forests was negatively associated with rainfall, and was highest in the dry season. Leaf fall in Eucalyptus plantations showed an opposite response, and peaked during the wet season. Decomposition experiments were carried out in the three habitats using 1200 litter bags (1 mm mesh) filled separately with leaves from four different species of tree, including an exotic plantation species ( E. urophylla) and trees typical of secondary ( Bellucia spp. and Vismia spp.) and primary forests ( Bertholettia excelsa). Litter bags were re-weighed at 3-month intervals 3, 6, 9 and 12 months after being placed on the forest floor. A repeated measures General Linear Model showed that litter decomposition was similar in the primary and secondary forest, and slowest in the Eucalyptus plantations. Leaves decomposed, from fastest to slowest, in the following order: E. urophylla > B. excelsa > Vismia spp. > Bellucia spp. There was no significant interaction between leaf species and habitat type. Our results indicate that secondary forests regenerating on abandoned and degraded Amazonian lands can be effective at restoring ecosystem processes such as litterfall and decomposition.

View angle effects on the discrimination of selected Amazonian land cover types from a principal‐component analysis of MISR spectra

Multi‐angle Imaging Spectroradiometer (MISR) data, collected in four bands and at nine view angles in the Brazilian Amazon region, were used to describe view‐angle effects on the spectral response and discrimination of three forest types; close and open lowland forests, open submontane forest and green/emerging pastures. A principal‐component analysis (PCA) was applied over 450 bidirectional reflectance factor (BRF) MISR spectra (10 pixels, five land covers and nine view angles) to characterize the spectral‐angular variability in the dataset and to identify the best view direction to enhance land cover discrimination. The analysis was extended into the images of the different cameras, which were classified for the presence of the forest covers using the minimum distance of the pixels to the average PC1 and PC2 scores of each forest class calculated from spectra analysis. Results showed an increase in the mean reflectance over the spectral bands (brightness) of the land covers from nadir to extreme viewing, as indicated by the first principal component, especially in the backward direction due to the predominance of sunlit view vegetation components. The transition from the backward (sunlit view surface components) to the forward (shaded view surface components) scattering directions was also characterized by changes in the shape of the BRF spectra, as indicated by decreasing PC2 score or near‐infrared/blue ratio values. The variations in the MISR BRF followed the regularities expected from theory. PCA results also indicated that the best viewing to discriminate the forest types was the backward scattering direction (−26.1° view angle), whereas the less favourable viewing was the forward scattering direction under the view shading condition (e.g. +45.6° view angle). The overall classification accuracy for the three forest types increased from 52.4% at +45.6° view angle to 78.7% at nadir, and to 95.0% at a −26.1° view angle. From nadir to extreme view angles, directional effects produced a NDVI decrease for the forest types and an NDVI increase for the green and especially emerging pastures. Results demonstrated that data acquisition in off‐nadir viewing may improve the discrimination and mapping of the Amazonian land cover types.

NITROGEN AND PHOSPHORUS CYCLING IN AN AMAZONIAN AGROFOREST EIGHT YEARS FOLLOWING FOREST CONVERSION

Commercial plantation agroforestry systems have emerged as a promising Amazonian land use with the potential to reduce soil degradation, improve living standards, and decrease pressures on remaining forested areas. While it is generally accepted that tree-based agroecosystems have more closed nutrient cycles that help conserve soil productivity, few studies of nutrient dynamics in Amazonian agroforestry systems exist, making it difficult to assess the extent to which this land use is sustainable in the region's weathered soils. We quantified net primary productivity (NPP) and the stocks and fluxes of carbon (C), nitrogen (N), and phosphorus (P) over one year in a commercial plantation agroforestry system in Acré, Brazil, to determine how organic matter and N and P dynamics change when native Amazonian forest is converted to perennial crops, and how nutrient cycling in tree-based agroecosystems compares with other Amazonian land uses. We used a participatory approach that involved farmers throughout the research process, with the aim of stimulating a community dialogue on the importance of nutrient cycling dynamics to sustained agricultural production. As part of this process, management recommendations to protect and enhance nutrient cycling in a manner practical for resource-limited households were formulated by farmers during focus group discussions. Construction of a nutrient budget revealed that the system's largest elemental stocks were located in the top 20 cm of soil. By the ninth year following establishment, agroforest productivity was high, with annual NPP approaching 3000 g·m−2·yr−1. Approximately 80% of the annual N and P requirements were taken up from soil stocks. Nearly 40% of the annual aboveground P requirement was allocated to reproductive tissues, half of which was removed with the harvest of agroforest products. Removal of P was half as much as would be expected for a first-year annual crop grown in a shifting cultivation system, while N export was similar to that of annual crops. Inputs of N and P to the agroforest were negligible, and resorption of N and P from agroforest leaves was comparable to rates cited for mature forest growing on similarly nutrient-poor soils. Return of P to the soil in litterfall exceeded that reported for mature Amazonian forests, despite similar rates of litter production and N flux, rendering agroforest P-use efficiency considerably lower than that reported for native vegetation growing on equally P-poor soils. Overall, NPP and rates of P cycling in the 8-yr-old agroforest were high relative to Amazonian forests, but low soil contents of total N and extractable P, as well as moderate rates of N and P removal, suggest that this land use will require inputs of both nutrients to sustain system productivity in the future. Discussions with farmers indicated that planting and pruning N-fixing legumes was a feasible way to add N, but the efficient use of scarce inorganic amendments would require further research.