|
Degen, B., & Roubilk, D. W. (2004). Effects of animal pollination on pollen dispersal, selfing, and effective population size of tropical trees: A simulation study. Biotropica, 36(2), 165–179.
Abstract: Animals, especially insects, are principal pollen vectors of tropical trees and have behavior patterns that affect gene dispersal. Here, we explore complex pollination systems using a new simulation model Eco-Gene and considering, among other factors, flowering synchrony. spatial distribution of trees, degree of selfing, population densities, pollinator flight distances, pollen deposition, and pollinator response to floral display size. Sensitivity analyses using two contrasting tree data sets (Jacaranda copaia and Dipteryx odorata) determined the importance of each parameter on three response variables: the proportion of seeds from self-pollination, effective population size, and pollen dispersal. Spatial considerations and attractiveness of floral displays were prominent features determining the population genetic result of pollinators, and some biological implications of the results are discussed.
Keywords: Amazon; bees; Brazil; Dipteryx; Jacaranda; model; pollination; sensitivity analysis; trees
|
|
|
Phillips, O. L., van der Heijden, G., Lewis, S. L., Lopez-Gonzalez, G., Aragao, L. E. O. C., Lloyd, J., et al. (2010). Drought-mortality relationships for tropical forests. New Phytol., 187(3), 631–646.
Abstract: The rich ecology of tropical forests is intimately tied to their moisture status. Multi-site syntheses can provide a macro-scale view of these linkages and their susceptibility to changing climates. Here, we report pan-tropical and regional-scale analyses of tree vulnerability to drought. We assembled available data on tropical forest tree stem mortality before, during, and after recent drought events, from 119 monitoring plots in 10 countries concentrated in Amazonia and Borneo. In most sites, larger trees are disproportionately at risk. At least within Amazonia, low wood density trees are also at greater risk of drought-associated mortality, independent of size. For comparable drought intensities, trees in Borneo are more vulnerable than trees in the Amazon. There is some evidence for lagged impacts of drought, with mortality rates remaining elevated 2 yr after the meteorological event is over. These findings indicate that repeated droughts would shift the functional composition of tropical forests toward smaller, denser-wooded trees. At very high drought intensities, the linear relationship between tree mortality and moisture stress apparently breaks down, suggesting the existence of moisture stress thresholds beyond which some tropical forests would suffer catastrophic tree mortality.
Keywords: Amazon; Borneo; drought; lags mortality; RAINFOR; trees; tropics
|
|
|
Perz, S. G., Qiu, Y., Xia, Y., Southworth, J., Sun, J., Marsik, M., et al. (2013). Trans-boundary infrastructure and land cover change: Highway paving and community-level deforestation in a tri-national frontier in the Amazon. Land Use Policy, 34, 27–41.
Abstract: Economic globalization manifests in landscapes through regional integration initiatives involving trans-boundary infrastructure. While the relationships of roads, accessibility and land cover are well-understood, they have rarely been considered across borders in national frontier regions. We therefore pursue an analysis of infrastructure connectivity and land cover change in the tri-national frontier of the southwestern Amazon where Bolivia, Brazil and Peru meet, and where the Inter-Oceanic Highway has recently been paved. We integrate satellite, survey, climate and other data for a sample of rural communities that differ in terms of highway paving across the tri-national frontier. We employ a suite of explanatory variables tied to road paving and other factors that vary both across and within the three sides of the frontier in order to model their importance for deforestation. A multivariate analysis of non-forest land cover during 2005-2010 confirms the importance of paving status and travel times, as well as land tenure and other factors. These findings indicate that integration affects land cover, but does not eliminate the effects of other factors that vary across the frontier, which bears implications for the study of globalization, trans-boundary infrastructure, environmental governance and land cover change. © 2013 Elsevier Ltd.
Keywords: Amazon; Brazil, Peru; Globalization; Infrastructure; Land
|
|
|
Odonne, G., Valadeau, C., Alban-Castillo, J., Stien, D., Sauvain, M., & Bourdy, G. (2013). Medical ethnobotany of the Chayahuita of the Paranapura basin (Peruvian Amazon). J. Ethnopharmacol., 146(1), 127–153.
Abstract: Ethnopharmacological relevance: Up until now, the plant pharmacopoeia of the Chayahuita, an ethnic group from the Peruvian Amazon, has been poorly defined. This paper details the uses of medicinal plants within this community, as recorded in two villages of the Paranapura basin, Soledad and Atahualpa de Conchiyacu. This study aimed to describe the basis of the Chayahuita traditional medical system, to document part of the medicinal plant corpus, and to compare it with data from other Amazonian ethnic groups. Material and methods: Methodology was based (i) on field prospection with 26 informants (ethnobotanical walks methodology), (ii) semi-structured interviews including 93 people (49 men and 44 women) focused on the most recent health problem experienced and on the therapeutic options chosen, (iii) individual or group thematic discussions relating to disease and treatments, (iv) 6-months of participants' observations between May 2007 and May 2008. At the end of the project in May 2008 a workshop was organized to cross-check the data with the help of 12 of the most interested informants. Results: Six hundred and seventeen voucher specimens were collected, corresponding to 303 different species, from which 274 (belonging to 83 families) are documented here. Altogether 492 recipes were recorded, corresponding to a global figure of 541 therapeutic uses and a total of 664 use reports. The main therapeutic uses are related to dermatological problems (103 uses; 19%), gastro-intestinal complaints (69 uses; 13%) and malaria/fevers (52 uses; 10%). Diseases are analysed according to Chayahuita concepts, and for each disease the species having a high frequency of citation are listed, and the most frequently used remedies are described. Whenever possible, comparisons with other Amazonian groups have been drawn. Conclusion: Chayahuita nosology and medical ethnobotany appear to draw their inspiration from a common panamazonian root. Despite the fact that a certain number of medicinal plants are shared with other nearby groups, there seem to be specific uses for some species, thus highlighting the originality of the Chayahuita pharmacopoeia. Presently there is a certain disinterest in the most traditional area of the Chayahuita medical ways, and the role of the penutu (shaman) seems to be less highly-valued than in the past. Nonetheless, the use of medicinal plants in phytotherapeutic treatment is very much a living, shared knowledge. © 2012 Elsevier Ireland Ltd. All rights reserved.
Keywords: Amazon; Chayahuita; Medicinal plant; Peru; Pharmacopeia; Traditional medicine
|
|
|
Longo, M., Saatchi, S., Keller, M., Bowman, K., Ferraz, A., Moorcroft, P. R., et al. (2020). Impacts of Degradation on Water, Energy, and Carbon Cycling of the Amazon Tropical Forests. J. Geophys. Res. Biogeosci., 125(8), e2020JG005677.
Abstract: Selective logging, fragmentation, and understory fires directly degrade forest structure and composition. However, studies addressing the effects of forest degradation on carbon, water, and energy cycles are scarce. Here, we integrate field observations and high-resolution remote sensing from airborne lidar to provide realistic initial conditions to the Ecosystem Demography Model (ED-2.2) and investigate how disturbances from forest degradation affect gross primary production (GPP), evapotranspiration (ET), and sensible heat flux (H). We used forest structural information retrieved from airborne lidar samples (13,500 ha) and calibrated with 817 inventory plots (0.25 ha) across precipitation and degradation gradients in the eastern Amazon as initial conditions to ED-2.2 model. Our results show that the magnitude and seasonality of fluxes were modulated by changes in forest structure caused by degradation. During the dry season and under typical conditions, severely degraded forests (biomass loss ≥66%) experienced water stress with declines in ET (up to 34%) and GPP (up to 35%) and increases of H (up to 43%) and daily mean ground temperatures (up to 6.5°C) relative to intact forests. In contrast, the relative impact of forest degradation on energy, water, and carbon cycles markedly diminishes under extreme, multiyear droughts, as a consequence of severe stress experienced by intact forests. Our results highlight that the water and energy cycles in the Amazon are driven by not only climate and deforestation but also the past disturbance and changes of forest structure from degradation, suggesting a much broader influence of human land use activities on the tropical ecosystems. ©2020. The Authors.
Keywords: Amazon; drought; ecosystem modeling; evapotranspiration; forest degradation; remote sensing; carbon cycle; deforestation; dry season; evapotranspiration; hydrological cycle; logging (timber); net primary production; remote sensing; sensible heat flux; tropical forest; understory; water stress; Amazon River
|
|
|
Fisher, J. B., Malhi, Y., Bonal, D., Da Rocha, H. R., De Araujo, A. C., Gamo, M., et al. (2009). The land-atmosphere water flux in the tropics. Glob. Change Biol., 15(11), 2694–2714.
Abstract: Tropical vegetation is a major source of global land surface evapotranspiration, and can thus play a major role in global hydrological cycles and global atmospheric circulation. Accurate prediction of tropical evapotranspiration is critical to our understanding of these processes under changing climate. We examined the controls on evapotranspiration in tropical vegetation at 21 pan-tropical eddy covariance sites, conducted a comprehensive and systematic evaluation of 13 evapotranspiration models at these sites, and assessed the ability to scale up model estimates of evapotranspiration for the test region of Amazonia. Net radiation was the strongest determinant of evapotranspiration (mean evaporative fraction was 0.72) and explained 87% of the variance in monthly evapotranspiration across the sites. Vapor pressure deficit was the strongest residual predictor (14%), followed by normalized difference vegetation index (9%), precipitation (6%) and wind speed (4%). The radiation-based evapotranspiration models performed best overall for three reasons: (1) the vegetation was largely decoupled from atmospheric turbulent transfer (calculated from X decoupling factor), especially at the wetter sites; (2) the resistance-based models were hindered by difficulty in consistently characterizing canopy (and stomatal) resistance in the highly diverse vegetation; (3) the temperature-based models inadequately captured the variability in tropical evapotranspiration. We evaluated the potential to predict regional evapotranspiration for one test region: Amazonia. We estimated an Amazonia-wide evapotranspiration of 1370 mm yr(-1), but this value is dependent on assumptions about energy balance closure for the tropical eddy covariance sites; a lower value (1096 mm yr(-1)) is considered in discussion on the use of flux data to validate and interpolate models.
Keywords: Amazon; eddy covariance; evaporation; evapotranspiration; ISLSCP-II; LBA; model; remote sensing; tropical
|
|
|
Fine, P. V. A., & Baraloto, C. (2016). Habitat Endemism in White-sand Forests: Insights into the Mechanisms of Lineage Diversification and Community Assembly of the Neotropical Flora. Biotropica, 48(1), 24–33.
Abstract: White-sand forests represent natural laboratories of evolution over their long history throughout Amazonia and the Guiana Shield and pose significant physiological challenges to the plants and animals they host. The study of diversification in plant lineages comprising species endemic to white-sand forest can therefore give insights into processes of evolution and community assembly in tropical forests. In this article, we synthesize recent studies of white-sand forests to integrate patterns of plant species distribution with processes of lineage diversification and community assembly in the white-sand flora. We contrast lineages that have radiated uniquely in these habitats (e.g., Pagamea, Rubiaceae), with cosmopolitan lineages comprising specialists to white-sand forests and other habitats that may have arisen via ecological speciation across habitat gradients (e.g., Protium, Burseraceae). In both cases, similar suites of functional traits have evolved, including investment in dense, long-lived tissues that are well-defended structurally and chemically. White-sand endemics, therefore, play an important role in biodiversity conservation because they represent unique combinations of functional and phylogenetic diversity. Furthermore, white-sand endemics may respond differently than other tropical forest plant species to contemporary global changes because they comprise resilient functional types that may better withstand increased drought, temperature, and invasions of exotic pests in these regions. © 2016 The Association for Tropical Biology and Conservation.
Keywords: Amazon; Endemic; Functional traits; Habitat specialization; Niche conservatism; Speciation
|
|
|
Guevara, J. E., Damasco, G., Baraloto, C., Fine, P. V. A., Peñuela, M. C., Castilho, C., et al. (2016). Low Phylogenetic Beta Diversity and Geographic Neo-endemism in Amazonian White-sand Forests. Biotropica, 48(1), 34–46.
Abstract: Over the past three decades, many small-scale floristic studies of white-sand forests across the Amazon basin have been published. Nonetheless, a basin-wide description of both taxonomic and phylogenetic alpha and beta diversity at regional scales has never been achieved. We present a complete floristic analysis of white-sand forests across the Amazon basin including both taxonomic and phylogenetic diversity. We found strong regional differences in the signal of phylogenetic community structure with both overall and regional Net Relatedness Index and Nearest Taxon Index values found to be significantly positive leading to a pattern of phylogenetic clustering. Additionally, we found high taxonomic dissimilarity but low phylogenetic dissimilarity in pairwise community comparisons. These results suggest that recent diversification has played an important role in the assembly of white-sand forests causing geographic neo-endemism patterns at the regional scale. © 2016 The Association for Tropical Biology and Conservation.
Keywords: Amazon; Neo-endemism; Phylogenetic beta diversity; Recent diversification; White sands
|
|
|
Fouquet, A., Ledoux, J. - B., Dubut, V., Noonan, B. P., & Scotti, I. (2012). The interplay of dispersal limitation, rivers, and historical events shapes the genetic structure of an Amazonian frog. Biol. J. Linn. Soc., 106(2), 356–373.
Abstract: Disentangling the impact of landscape features such as rivers and historical events on dispersal is a challenging but necessary task to gain a comprehensive picture of the evolution of diverse biota such as that found in Amazonia. Adenomera andreae, a small, territorial, terrestrial frog species of the Amazonian forest represents a good model for such studies. We combined cytochromeb sequences with 12 microsatellites to investigate the genetic structure at two contrasted spatial scales in French Guiana: along a ∼6-km transect, to evaluate dispersal ability, and between paired bank populations along a ∼65-km stretch of the Approuague river, to test the effect of rivers as barriers to dispersal. We observed significant spatial genetic structure between individuals at a remarkably small geographical scale, and conclude that the species has a restricted dispersal ability that is probably tied to its life-history traits. Mitochondrial and microsatellite data also indicate a high level of differentiation among populations on opposite banks of the river, and, in some cases, among populations on the same riverbank. These results suggest that the observed population structure in A.andreae is the result of restricted dispersal abilities combined with the action of rivers and Quaternary population isolation. Given that Amazonia hosts a great portion of anurans, as well as other small vertebrates, that display life-history traits comparable with A.andreae, we argue that our analyses provide new insights into the complex interactions among evolutionary processes shaping Amazonian biodiversity. © 2012 The Linnean Society of London.
Keywords: Amazonia; Amphibian; Gene flow; Microsatellites; Mitochondrial DNA; Spatial genetic structure
|
|
|
Ogeron, C., Odonne, G., Cristinoi, A., Engel, J., Grenand, P., Beauchene, J., et al. (2018). Palikur traditional roundwood construction in eastern French Guiana: Ethnobotanical and cultural perspectives. Journal of Ethnobiology and Ethnomedicine, 14(28).
Abstract: Background: Palikur Amerindians live in the eastern part of French Guiana which is undergoing deep-seated changes due to the geographical and economic opening of the region. So far, Palikur's traditional ecological knowledge is poorly documented, apart from medicinal plants. The aim of this study was to document ethnobotanical practices related to traditional construction in the region. Methods: A combination of qualitative and quantitative methods was used. Thirty-nine Palikur men were interviewed in three localities (Saint-Georges de l'Oyapock, Regina and Trois-Palétuviers) between December 2013 and July 2014. Twenty-four inventories of wood species used in traditional buildings were conducted in the villages, as well as ethnobotanical walks in the neighboring forests, to complete data about usable species and to determine Linnaean names. Results: After an ethnographic description of roundwood Palikur habitat, the in situ wood selection process of Palikur is precisely described. A total of 960 roundwood pieces were inventoried in situ according to Palikur taxonomy, of which 860 were beams and rafters, and 100 posts in 20 permanent and 4 temporary buildings. Twenty-seven folk species were identified. Sixty-three folk species used in construction were recorded during ethnobotanical walks. They correspond to 263 botanical species belonging to 25 families. Posts in permanent buildings were made of yawu (Minquartia guianensis) (51%) and wakap (Vouacapoua americana) (14%). Beams and rafters were made of wood from Annonaceae (79%) and Lecythidaceae (13%) families. The most frequently used species were kuukumwi priye (Oxandra asbeckii), kuukumwi seyne (Pseudoxandra cuspidata), and pukuu (Xylopia nitida and X. cayennensis). Conclusions: Although the Palikur's relationship with their habitat is undergoing significant changes, knowledge about construction wood is still very much alive in the Oyapock basin. Many people continue to construct traditional buildings alongside modern houses, using a wide array of species described here for the first time, along with the techniques used.
Keywords: Amazonia; Annonaceae; Architecture; Non-timber forest products; Oyapock; Palikur; Sapotaceae; Traditional technological knowledge
|
|