Brazilian Tropical Forest Research Articles

Seasonal Ecosystem Productivity in a Seasonally Dry Tropical Forest (Caatinga) Using Flux Tower Measurements and Remote Sensing Data

The Caatinga dry forest encompasses 11% of the total continental territory of Brazil. Nevertheless, most research on the relationship between phenology and ecosystem productivity of Brazilian tropical forests is aimed at the Amazon basin. Thus, in this study we evaluated the seasonality of ecosystem productivity (gross primary production—GPP) in a preserved Caatinga environment in northeast Brazil. Analyses were carried out using eddy covariance measurements and satellite-derived data from sensor MODIS (MODerate Resolution Imaging Spectroradiometer, MOD17 and MOD13 products). In addition to GPP, we investigated water use efficiency (WUE) and meteorological and phenological aspects through remotely sensed vegetation indices (NDVI and EVI). We verified that ecosystem productivity is limited mainly by evapotranspiration, with maximum GPP values registered in the wetter months, indicating a strong dependency on water availability. NDVI and EVI were positively associated with GPP (r = 0.69 and 0.81, respectively), suggesting a coupling between the emergence of new leaves and the phenology of local photosynthetic capacity. WUE, on the other hand, was strongly controlled by consecutive dry days and not necessarily by total precipitation amount. The vegetation indices adequately described interannual variations of the forest response to environmental factors, and GPP MODIS presented a good relationship with tower-measured GPP in dry (R2 = 0.76) and wet (R2 = 0.62) periods.

An ethnogeomorphic case study of conservation practices in Southeast Brazil

Controversy and conflict surround the design and implementation of protected areas in tropical forests in Brazil. This case study applies an ethnogeomorphic perspective to relate local understandings of landscape to conservation goals in a protected area in Rio de Janeiro State. Externally imposed environmental protection areas fail to incorporate understandings of local farmer practices that shaped the landscape notionally being protected. Rather, a focus on reafforestation and technocentric farming techniques ignores flexible and adaptive land use practices in managing the protected area. Findings show that ethnogeomorphic research that generates multiple readings of landscapes could support more inclusive, locally informed conservation programmes.

Teleconnections and edaphoclimatic effects on tree growth of Cedrela odorata L. in a seasonally dry tropical forest in Brazil

The Seasonally Dry Tropical Forests (SDTF) present very high biodiversity and a number of tree species that are adapted to prolonged periods of water stress. Considering tree ring formation is mainly driven by seasonal variation in precipitation in tropical environments, tree-ring studies from STDF can provide important contributions to understanding how these forests are responding to climate variations. In the present study, we demonstrate the influence of edaphoclimatic variables (precipitation, air temperature and soil water deficit-SWD) and the ocean teleconnections (Tropical Southern Atlantic-TSA, Atlantic Multidecadal Oscillation-AMO, Western Hemisphere Warm Pool-WHWP and El Niño 3.4) on Cedrela odorata L. growth from a SDTF of northeastern Brazil. We used standard dendrochronological methods to develop an 89-year-long ring-width index chronology. The climate sensitivity of C. odorata was assessed through Pearson's correlation tests and linear regressions, which allowed to identify the determinant months (cause-effect) of each variable on the chronology. Tree growth was positively correlated with precipitation and negatively correlated with air temperature and SWD, particularly during the rainy season (March to August). In parallel, we identified that extremely dry years can contribute to missing rings, exposing the lack of growth in C. odorata caused by water stress. Among the oceanic variables, all of them showed a negative effect on radial growth of C. odorata, except for TSA, which had no significant effect. Tree growth is constrained in years with strong El Niño and high values of AMO index during the rainy months (May, June and October). However, the WHWP showed a more pronounced negative effect in the beginning of the dry season (September). Our findings add valuable information on C. odorata responses to hydrological seasonality from SDTF and the fluctuations in oceanic teleconnections, which in turn, influence the rainfall dynamics in northeastern Brazil.

Seedling physiological responses from Ceiba glaziovii (Kutze) K. Skum. to intermittent drought events

The Brazilian Dry Tropical Forest, called Caatinga, has several environmental conditions limiting plant growth and development, requiring the plants that inhabit this phytogeographic domain, physiological and morphological traits to guarantee the perpetuation and survival of the species. The objective of the present work was to evaluate the growth parameters in Ceiba glaziovii, a tree species that occurs in the Caatinga, submitted to intermittent drought. For such seedling of C. glaziovii were subjected to different cycles of irrigation suspension [Control- daily irrigation, S7- irrigation every seven days and SS - total suspension of irrigation until signs of wilt appear]. Height, number of leaves, stem diameter, dry matter of the various organs, root / shoot ratio, leaf area, and the index of plasticity were evaluated. The prolongation of intermittent drought had a significant reducing effect on the growth rates, dry matter production and leaf area of stressed C. glaziovii seedlings compared to daily watering ones. Plant height and stem diameter were the most plastic traits found (IP>0,8). Thus, watering intervals above seven days may severely compromise the production of C. glaziovii seedlings, affecting the growth rates until the accumulation of dry matter. These results demonstrate that this species does not show great tolerance to drought stress during the initial period of its development, suggesting for cultivation of seedlings an adequate water availability or an interval of up to seven days between watering.

Towards the automatic monitoring of deforestation in Brazilian rainforest

Deforestation is considered one of the main environmental threats to the ecological balance on the planet. At the same time, monitoring changes in forest cover is a major challenge, especially in Brazil, a country with continental dimensions, a vast coverage of tropical forests, and an accelerated ongoing process of illegal deforestation. This study aims to propose and present an integrated automatic methodology for monitoring changes in forest cover, to enable “near real-time” monitoring of vast territorial extensions. Based on the application of Fully Convolutional Neural Networks (FCNs) combined with a logistic growth model, the methodology is aimed at allowing accurate detection of changes in forest cover based on the multitemporal assessment of satellite images. The results show that the combination of the two approaches make the methodology able to pinpoint deforestation processes. The applicability of the methodology is demonstrated for the Amazon and Atlantic Rainforest biomes, which are important areas of tropical forests in Brazil. In addition to enabling the agile and accurate identification of forest cover losses and providing efficient computing, the comparative results show that the methodology can be applied to issue alerts of suspected deforestation activity in standalone automatic monitoring systems, and also as a complementary tool to existing systems currently under operation.

Bat-ectoparasitic fly relationships in a seasonally dry tropical forest in Brazil.

Bat ectoparasitic flies are hematophagous insects highly specialized to parasitize only bats. Knowledge about how biotic and abiotic factors can influence ecological relationships between parasites and hosts is in general incipient. Large information gaps are even worst in biodiversity-rich, but poorly sampled areas like Brazil's Caatinga, the largest tropical dry forest in South America. We used bats and their highly specialized ectoparasitic flies as a study model to clarify some aspects of this host-parasite system in this semiarid environment. We conducted fieldwork at 55 sites in the Caatinga, between April 2017 and March 2020 and collected 1300 flies (19 species) on 333 bats (15 species). Bat ectoparasitic flies were highly host-specific, had an aggregated distribution, frequently formed infracommunities with only one species, and had a male-biased sex ratio. Except for the prevalence of the streblid fly Strebla guajiro on Carollia perspicillata, which was significantly higher in the rainy season, bat flies showed no preference - expressed by frequency and intensity of infestation - for host sex, and their interspecific relationships were not mediated by rainfall. Other variables that could potentially be interfering in this host-parasite relationship deserve further attention, especially in environments such as the Caatinga where there is great seasonal variation. Furthermore, the existence of species-specific responses must be taken into account.

A Double-Headed Turtle God

When I was asked to comment on the illustration printed on the cover of the first (1961) volume of the journal L’Homme, I was honored to have my name associated with the inimitable Claude Levi-Strauss, the founder of structuralist anthropology, which was nurtured by the tropical forests of Brazil and nourished by the exceptionally diverse ethnic groups whose forebears had lived there for millennia. I myself am an archaeologist, and when I arrived in the Republic of Panama in 1969 to begin the...

Effects of domestic wood collection on tree community structure in a human-dominated seasonally dry tropical forest

Domestic wood collection affects plant communities through constant biomass removal. We assessed the effects of wood collection for firewood and fence construction on tree community structure in a seasonally dry tropical forest in Brazil. We described the harvest patterns of wood products. Further, we evaluated the effects of rainfall levels and wood collection on tree community structure. Most wood collection for firewood was concentrated within a small subset of dominant species. Wood collection for building fences was less influenced by species abundance. Species richness was positively associated with rainfall. Wood collection increased community evenness and negatively affected total density. The dominant species were not affected by wood collection. Domestic use of wood has a low impact on tree diversity in human-dominated dry forests. Nevertheless, some of the most used species for building fences are potentially threatened. The effects of firewood collection can be mitigated through (1) offering subsidies aimed at fuel transition to liquefied petroleum gas or (2) developing and distributing more efficient cookstoves. The effects of wood collection for building fences can be mitigated through promoting the use of (1) living fences or (2) fewer stakes. In addition, the populations of the most commonly used species should be recovered.

How bamboo influences the seed bank and biotic and abiotic factors of a Brazilian tropical forest

There is a knowledge gap regarding the influence of bamboos on natural regeneration. This study evaluated how abundance, richness, dominance, evenness, diversity of the seed bank and biotic and abiotic factors (e.g., canopy opening, herbaceous cover, and litter thickness), differ between bamboo dominated (B) and non-dominated (NB) areas. The study was conducted in a fragment of Semideciduous Seasonal Forest surrounded by an agricultural landscape. Soil samples were taken at 20 points in each area at two time periods, to evaluate the seed bank. The results show that diversity and structural parameters of the seed bank differ between areas and time periods. There was higher abundance and richness of seedlings of herbaceous ruderal species in area B and a greater abundance of seedlings of arboreal species in area NB. Sampling points in the bamboo dominated area had greater canopy openings and greater cover by herbaceous species, facilitating the establishment of individuals belonging to the families Poaceae and Cyperaceae, which could have competitive advantages over other species of the regenerating community. Considering that bamboo can affect the seed bank, long-term studies are needed to understand successional dynamics and evaluate suitable management actions to conserve the diversity in remaining forests.

The diversity of foliicolous lichens on ferns in two Brazilian tropical forests

A more complete picture of the function of plants in ecosystems results from understanding biotic interactions and this study examined the interactions between ferns and foliicolous lichens. A sampling method involving 15-h walks in each of two tropical forests in Brazil was employed to assess foliicolous lichen diversity on ferns. The nature of foliicolous lichen-fern interactions, and their relationship with forest types (lowland and submontane) and leaf traits (hairs and leaf area), was investigated. Eleven fern species were found to be hosts to 30 foliicolous lichen taxa. Telmatoblechnum serrulatum and Meniscium longifolium were considered the key hosts harboring a greater number (18 and 12) of lichen taxa, of which five taxa were restricted to these two ferns. Approximately 55% of the foliicolous lichens were found on a single fern host. Thicharia sp. A and Gyalectidium filicinum were the more interactive taxa, occurring on seven and ten host ferns, respectively. The forest type had no influence on the interactions. The foliicolous lichen-host fern network differed significantly from null expectations, and there was no sign of specialization. There was also no variation related to the presence of hairs on the sampled ferns (80% had glabrous leaves) and leaf hairs had no significant influence on lichen diversity. Furthermore, leaf area had no influence on the diversity of lichen species. Our results provide a first picture of diversity of foliicolous lichens on fern assemblages in tropical forests. However, there are uncertainties about the mechanisms driving these interactions so more research is needed.

Modeling and Spatialization of Biomass and Carbon Stock Using LiDAR Metrics in Tropical Dry Forest, Brazil

In recent years, with the growing environmental concern regarding climate change, there has been a search for efficient alternatives in indirect methods for the quantification of biomass and forest carbon stock. In this article, we seek to obtain pioneering results of biomass and carbon estimates from forest inventory data and LiDAR technology in a dry tropical forest in Brazil. We use forest inventory data in two areas together with data from the LiDAR flyby, generating estimates of local biomass and carbon levels obtained from local species. We approach three types of models for data analysis: Multiple linear regression with principal components (PCA), conventional multiple linear regression and stepwise multiple linear regression. The best fit total above ground biomass (TAGB) and total above ground carbon (TAGC) model was the stepwise multiple linear regression, concluding, then, that LiDAR data can be used to estimate biomass and total carbon in dry tropical forest, proven by an adjustment considered in the models employed, with a significant correlation between the LiDAR metrics. Our finding provides important information about the spatial distribution of TAGB and TAGC in the study area, which can be used to manage the reserve for optimal carbon sequestration.

Novelties in Lactifluus subg. Gymnocarpi (Russulales, Basidiomycota) from Brazilian tropical forests

Lactifluus is an ectomycorrhizal genus that occurs predominantly in the tropical and subtropical regions. In Brazil, knowledge of species diversity in Lactifluus is restricted to the Amazon, Atlantic Forest, and Caatinga biomes, where several species have been described in subgenera Lactariopsis and Pseudogymnocarpi. Until now, subg. Gymnocarpi was represented in Brazil only by Lf. panuoides. Based on morphological and phylogenetic analyses, three novel species of Lf. subg. Gymnocarpi are described from Brazilian tropical forests: Lf. guttulatus, Lf. piperogalactus, and Lf. spathuliformis. Lactifluus lepus, originally described in the Caribbean, has been found in a dense ombrophilous forest of Amazon and is also described, illustrated, and discussed. A combined dataset of nuclear rDNA internal transcribed spacer region (ITS) and RNA polymerase II second largest subunit (RPB2) was analyzed. Based on phylogenetic and morphological data, the agaricoid sect. Piperogalacti is erected and the pleurotoid sect. Panuoidei is emended.

Soil carbon dynamics in Brazilian Atlantic forest converted into pasture‐based dairy production systems

AbstractThe conversion of Brazilian tropical forests into pastureland was a complex process, potentially harmful to the environment, heightened by degraded grazing systems that did not ensure sustainability and affected the ecosystem resilience. This study was conducted to determine the long‐term changes in soil C stocks in native forest (FOR) converted to pasture‐based dairy systems (continuous grazing system with low stocking rate–CLS; rotational grazing system with high stocking rate–RHS). Soil samples were analyzed for texture, C, organic matter (OM), bulk density (BD), C stock, and carbon accumulation rates (CAR) in 0‐to‐5‐, 5‐to‐10‐, 10‐to‐20‐, 20‐to‐30‐, 30‐to‐40‐, 40‐to‐60‐, 60‐to‐80‐, and 80‐to‐100‐cm depths in six trenches. Bulk density was higher in RHS compared with CLS and FOR in most of the soil layers. In the 0‐to‐5‐cm layer, C and OM were greater in CLS. Carbon contents were similar in RHS and FOR, whereas OM was higher in FOR. Intensification increased BD, reduced OM, and did not affect C content in the 0‐to‐5 cm layer. For all treatments, C stock and CAR were higher in the 0‐to‐100 cm (136.73 Mg ha−1 and 0.4252 Mg ha−1 yr−1) than the 0‐to‐30 cm (61.79 Mg ha−1 and 0.0447 Mg ha−1 yr−1) layer. The soil C stock remained equal for both pastureland and presented a positive CAR in relation to the forest, working as C sinks. The RHS presented the greatest forage yield, carrying capacity and milk yield. This management resulted in a land‐saving effect of 2.7 ha for each hectare of high intensified pasture.

Understanding the effects of human disturbance on scorpion diversity in Brazilian tropical forests

The effects of land use conversion on the maintenance of biodiversity remains a major issue in conservation biology. With this as context, recent studies have successfully evaluated the potential of scorpions as bio-indicators of human disturbance. Here, we explored this assumption to identify the effects of landscape structure on scorpion assemblages distributed in two tropical environments in Brazil, with different levels of human disturbance. Scorpions were collected from 28 sampling localities across the Atlantic Forest (n = 12) and Caatinga dry forest (n = 16), resulting in 3,781 specimens from 13 species, 5 genera, and 2 families. We found that scorpion species composition and abundance were more sensitive to changes in landscape configuration than was species richness. Additionally, scorpion assemblage responses were quite different between the two environments. From this observation we highlighted three main findings: (i) the Atlantic Forest assemblage possesses an abundance-dependent response to landscape; (ii) variation in species composition of Atlantic Forest and Caatinga were affected by landscape diversity and presence of croplands, respectively; (iii) the Atlantic Forest is inhabited by assemblages that are more sensitive to landscape changes than that is Caatinga. We argue that a site-dependent process may explain the effects of human activities on scorpion assemblages at local and regional scale. Moreover, we provide substantial information for decision-makers to support their conservation strategies for neglected ecosystems, such as those present in Caatinga and the Atlantic Forest.

Above and belowground carbon stock in a tropical forest in Brazil

An increase in atmospheric CO2 levels and global climate changes have led to an increased focus on CO2 capture mechanisms. The in situ quantification and spatial patterns of forest carbon stocks can provide a better picture of the carbon cycle and a deeper understanding of the functions and services of forest ecosystems. This study aimed to determine the aboveground (tree trunks) and belowground (soil and fine roots, at four depths) carbon stocks in a tropical forest in Brazil and to evaluate the spatial patterns of carbon in the three different compartments and in the total stock. Census data from a semideciduous seasonal forest were used to estimate the aboveground carbon stock. The carbon stocks of soil and fine roots were sampled in 52 plots at depths of 0-20, 20-40, 40-60, and 60-80 cm, combined with the measured bulk density. The total estimated carbon stock was 267.52 Mg ha-1, of which 35.23% was in aboveground biomass, 63.22% in soil, and 1.54% in roots. In the soil, a spatial pattern of the carbon stock was repeated at all depths analyzed, with a reduction in the amount of carbon as the depth increased. The carbon stock of the trees followed the same spatial pattern as the soil, indicating a relationship between these variables. In the fine roots, the carbon stock decreased with increasing depth, but the spatial gradient did not follow the same pattern as the soil and trees, which indicated that the root carbon stock was most likely influenced by other factors.

Biomass Dynamics in a Fragment of Brazilian Tropical Forest (Caatinga) over Consecutive Dry Years

Increases in water scarcity due to climate change, especially in dry regions, can affect the dynamics of successional species. In view of the longest sequence of dry years (2010–2019) to have occurred in the Brazilian semi-arid region, with a consequent reduction in water availability, the influence of rainfall distribution on the production of above-ground plant biomass was investigated in a Dry Tropical Forest (DTF). This natural change monitoring experiment was conducted over 11 years (2009–2019) in a fragment of DTF under regeneration for 40 years, in the district of Iguatu, Ceará, Brazil. All living individuals of the woody component with a Diameter at Ground Level (DGL) ≥3 cm and a height (h) ≥100 cm were measured during 2009–2010, 2015–2016, 2018–2019. Biomass production was calculated using an allometric equation defined for DTF species. A mean mortality rate of 134 ind. ha−1 yr−1 was registered, with a recruitment of 39 ind. ha−1 yr−1, generating a mean deficit of 95 ind. ha−1 yr−1. The mean reduction in biomass was 3.26 Mg ha−1 yr−1. Climate conditions during consecutive dry years have a direct effect on the mortality and recruitment of woody species, with a recruitment/mortality ratio of 0.11. Shrubby-tree individuals of smaller diameter showed less resilience to the cumulative effect of drought.

Improving wood volume predictions in dry tropical forest in the semi-arid Brazil

The volumetric variability of dry tropical forests in Brazil and the scarcity of studies on the subject show the need for the development of techniques that make it possible to obtain adequate and accurate wood volume estimates. In this study, we analyzed a database of thinning trees from a forest management plan in the Contendas de Sincorá National Forest, southwestern Bahia State, Brazil. The data set included a total of 300 trees with a trunk diameter ranging from 5 to 52 cm. Adjustments, validation and statistical selection of four volumetric models were performed. Due to the difference in height values for the same diameter and the low correlation between both variables, we do not suggest models which only use the diameter at breast height (DBH) variable as a predictor because they accommodate the largest estimation errors. In comparing the best single entry model (Hohenald-Krenn) with the Spurr model (best fit model), it is noted that the exclusion of height as a predictor causes the values of 136.44 and 0.93 for Akaike information criterion (AIC) and adjusted determination coefficient (R 2adj ), which are poorer than the second best model (Schumacher-Hall). Regarding the minimum sample size, errors in estimation (root mean square error (RMSE) and bias) of the best model decrease as the sample size increases, especially when a larger number of trees with DBH ≥ 5.0 cm are randomly sampled. Stratified sampling by diameter class produces smaller volume prediction errors than random sampling, especially when considering all trees. In summary, the Spurr and Schumacher-Hall models perform better. These models suggest that the total variance explained in the estimates is not less than 95%, producing reliable forecasts of the total volume with shell. Our estimates indicate that the bias around the average is not greater than 7%. Our results support the decision to use regression methods to build models and estimate their parameters, seeking stratification strategies in diameter classes for the sample trees. Volume estimates with valid confidence intervals can be obtained using the Spurr model for the studied dry forest. Stratified sampling of the data set for model adjustment and selection is necessary, since we find significant results with mean error square root values and bias of up to 70% of the total database.

Automated estimation of forest height and underlying topography over a Brazilian tropical forest with single-baseline single-polarization TanDEM-X SAR interferometry

Forest height is an important variable for modeling terrestrial carbon storage and global carbon cycle dynamics. Spaceborne SAR Interferometry (InSAR) has the sensitivity to measure canopy height and the underlying topography. In this paper, we refine and automate an interferometric ground finding approach that exploits few-look (2- to 4-look) averaged interferograms and incorporates the use of a coherent electromagnetic simulator and field inventory data. Using the coherent electromagnetic simulator, an InSAR simulation based on field data is performed to study the true ground position as a function of the statistics of few-look InSAR phase heights from a model perspective. With this statistical model, both the underlying topography and the canopy height (mean and top canopy height) can be estimated. Using German Aerospace Center's (DLR) single-baseline single-polarization TanDEM-X InSAR data, we validate the approach over a Brazilian tropical forest (Tapajós National Forest) with both field inventory and lidar data. As validated against lidar data, the underlying topography is estimated to an accuracy of 3 m. At one hectare aggregated pixel size, InSAR phase-center height is best compared with the field/lidar mean canopy height with an accuracy of 2–3 m, while InSAR-inverted total height best characterizes the lidar top canopy height with an accuracy of 4–5 m. Given the global data availability of TanDEM-X and the future TanDEM-L, this approach has the potential for wall-to-wall mapping of forest height as well as underlying topography and also serves as a complementary tool to other existing InSAR, Polarimetric InSAR (PolInSAR) and SAR tomography (TomoSAR) methods when only single polarization and/or baseline data are available.

Edge effects on trophic cascades in tropical rainforests.

The cascading effects of biodiversity loss on ecosystem functioning of forests have become more apparent. However, how edge effects shape these processes has yet to be established. We assessed how edge effects alter arthropod populations and the strength of any resultant trophic cascades on herbivory rate in tropical forests of Brazil. We established 7 paired forest edge and interior sites. Each site had a vertebrate-exclosure, procedural (exclosure framework with open walls), and control plot (total 42 plots). Forest patches were surrounded by pasture. Understory arthropods and leaf damage were sampled every 4 weeks for 11 months. We used path analysis to determine the strength of trophic cascades in the interior and edge sites. In forest interior exclosures, abundance of predaceous and herbivorous arthropods increased by 326% and 180%, respectively, compared with control plots, and there were significant cascading effects on herbivory. Edge-dwelling invertebrates responded weakly to exclusion and there was no evidence of trophic cascade. Our results suggest that the vertebrate community at forest edges controls invertebrate densities to a lesser extent than it does in the interior. Edge areas can support vertebrate communities with a smaller contingent of insectivores. This allows arthropods to flourish and indirectly accounts for higher levels of plant damage at these sites. Increased herbivory rates may have important consequences for floristic community composition and primary productivity, as well as cascading effects on nutrient cycling. By interspersing natural forest patches with agroforests, instead of pasture, abiotic edge effects can be softened and prevented from penetrating deep into the forest. This would ensure a greater proportion of forest remains habitable for sensitive species and could help retain ecosystem functions in edge zones.

Mapping data gaps to estimate biomass across Brazilian Amazon forests

BackgroundTropical forests play a fundamental role in the provision of diverse ecosystem services, such as biodiversity, climate and air quality regulation, freshwater provision, carbon cycling, agricultural support and culture. To understand the role of forests in the carbon balance, aboveground biomass (AGB) estimates are needed. Given the importance of Brazilian tropical forests, there is an urgent need to improve AGB estimates to support the Brazilian commitments under the United Nations Framework Convention on Climate Change (UNFCCC). Many AGB maps and datasets exist, varying in availability, scale and coverage. Thus, stakeholders, policy makers and scientists must decide which AGB product, dataset or combination of data to use for their particular goals. In this study, we assessed the gaps in the spatial AGB data across the Brazilian Amazon forests not only to orient the decision makers about the data that are currently available but also to provide a guide for future initiatives.ResultsWe obtained a map of the gaps in the forest AGB spatial data for the Brazilian Amazon using statistics and differences between AGB maps and a spatial multicriteria evaluation that considered the current AGB datasets. The AGB spatial data gap map represents areas with good coverage of AGB data and, consequently, the main gaps or priority areas where further biomass assessments should focus, including the northeast of Amazon State, Amapá and northeast of Pará. Additionally, by quantifying the variability in both the AGB maps and field data on multiple environmental factors, we provide valuable elements for understanding the current AGB data as a function of climate, soil, vegetation and geomorphology.ConclusionsThe map of AGB data gaps could become a useful tool for policy makers and different stakeholders working on National Communications, Reducing Emissions from Deforestation and Degradation (REDD+), or carbon emissions modeling to prioritize places to implement further AGB assessments. Only 0.2% of the Amazon biome forest is sampled, and extensive effort is necessary to improve what we know about the tropical forest.