Arc Of Deforestation Research Articles

Aquatic and Semiaquatic Heteroptera (Hemiptera: Insecta) Distribution in Streams on the Cerrado–Amazon Ecotone in Headwaters of Xingu River

The modification of landscapes surrounding water bodies leads to changes in limnological characteristics and decreased aquatic biodiversity, such as fish and macroinvertebrates. Aquatic insects are sensitive to changes in aquatic ecosystems and quickly respond to those changes. The aim of this paper was to evaluate the relationship between the compositions of aquatic and semi-aquatic Heteroptera with environmental variables along an environmental gradient in streams at the headwaters of the Xingu River, Brazil. We collected samples from 12 streams belonging to the Suiá-Miçú river basin and tributaries of the Xingu River, in September (dry season), 2008. The Suiá-Miçú river is one of the tributaries on the right bank of the Xingu River, and it is located in the ecotone between the Cerrado and the Amazon rainforest in the area characterized as the “arc of deforestation’’. Insects were sampled in fixed 100 m transections and divided into 20 segments of 5 meters each. To assess the habitat integrity in each stream, the habitat integrity index (HII) was applied. The following environmental variables were measured: electrical conductivity, turbidity, depth, and the normalized difference vegetation index (NDVI). The ordering of species composition was performed with the principal coordinate analysis (PCoA), and the relationship between environmental variables and composition was performed using a Mantel test. Of the 263 individuals collected, distributed in 8 families, there were 20 genera, of these, 12 were from Nepomorpha and 8 from Gerromorpha. The most abundant genera were Limnocoris (n = 121) and Rhagovelia (n = 32). Naucoridae was the most diverse family. Together, the environmental variables explained ~50% of the species distribution (r = 0.49; p = 0.001). These results reinforce the efficacy of aquatic Heteroptera to monitor environmental conditions. Here, in particular, the responses of this group to variations in landscape metrics, environmental integrity, and water variables together demonstrate that it can be useful to indicate the quality of habitat in streams.

Relationship between Land Use and Spatial Variability of Atmospheric Brown Carbon and Black Carbon Aerosols in Amazonia

The aerosol radiative effect is an important source of uncertainty in estimating the anthropogenic impact of global climate change. One of the main open questions is the role of radiation absorption by aerosols and its relation to land use worldwide, particularly in the Amazon Rainforest. Using AERONET (Aerosol Robotic Network) long-term measurements of aerosol optical depth (AOD) at a wavelength of 500 nm and absorption AOD (AAOD) at wavelengths of 440, 675, and 870 nm, we estimated the fraction and seasonality of the black carbon (BC) and brown carbon (BrC) contributions to absorption at 440 nm. This was conducted at six Amazonian sites, from central Amazon (Manaus and the Amazon Tall Tower Observatory—ATTO) to the deforestation arc (Rio Branco, Cuiabá, Ji-Paraná, and Alta Floresta). In addition, land use and cover data from the MapBiomas collection 6.0 was used to access the land transformation from forest to agricultural areas on each site. The results showed, for the first time, important geographical and seasonal variability in the aerosol optical properties, particularly the BC and BrC contributions. We observed a clear separation between dry and wet seasons, with BrC consistently accounting for an average of approximately 12% of the aerosol AAOD at 440 nm in the deforestation arc. In central Amazon, the contribution of BrC was approximately 25%. A direct relationship between the reduction in forests and the increase in the area dedicated to agriculture was detected. Moreover, places with lower fractions of forest had a smaller fraction of BrC, and regions with higher fractions of agricultural areas presented higher fractions of BC. Therefore, significant changes in AOD and AAOD are likely related to land-use transformations and biomass burning emissions, mainly during the dry season. The effects of land use change could introduce differences in the radiative balance in the different Amazonian regions. The analyses presented in this study allow a better understanding of the role of aerosol emissions from the Amazon Rainforest that could have global impacts.

Dynamics of Fire Foci in the Amazon Rainforest and Their Consequences on Environmental Degradation

Burns are common practices in Brazil and cause major fires, especially in the Legal Amazon. This study evaluated the dynamics of the fire foci in the Legal Amazon in Brazil and their consequences on environmental degradation, particularly in the transformation of the forest into pasture, in livestock and agriculture areas, mining activities and urbanization. The fire foci data were obtained from the reference satellites of the BDQueimadas of the CPTEC/INPE for the period June 1998–May 2022. The data obtained were subjected to descriptive and exploratory statistical analysis, followed by a comparison with the PRODES data during 2004–2021, the DETER data (2016–2019) and the ENSO phases during the ONI index for the study area. Biophysical parameters were used in the assessment of environmental degradation. The results showed that El Niño’s years of activity and the years of extreme droughts (2005, 2010 and 2015) stand out with respect to significant increase in fire foci. Moreover, the significant numbers of fire foci indices during August, September, October and November were recorded as 23.28%, 30.91%, 15.64% and 10.34%, respectively, and these were even more intensified by the El Niño episodes. Biophysical parameters maps showed the variability of the fire foci, mainly in the south and west part of the Amazon basin referring to the Arc of Deforestation. Similarly, the states of Mato Grosso, Pará and Amazonas had the highest alerts from PRODES and DETER, and in the case of DETER, primarily mining and deforestation (94.3%) increased the environmental degradation. The use of burns for agriculture and livestock, followed by mining and wood extraction, caused the degradation of the Amazon biome.

Fire probability mapping and prediction from environmental data: What a comprehensive savanna-forest transition can tell us

The Cerrado-Amazon transition (CAT) is located between the two largest biogeographic domains of the Neotropical region, coinciding with the “Arc of Deforestation”, an agricultural frontier that expands towards the Amazon. Fire plays an important role in the landscape changes that have been occurring in this transition. Thus, the objectives of this study were (i) evaluate the accuracy of different algorithms/techniques in predicting fires in the CAT; (ii) investigate the season of highest fire probabilities in the CAT; and (iii) identify, among anthropic, climatic, topographic and soil variables, the main drivers of fires spatial distribution in the CAT. Fire occurrence data (active fire pixels) from the MODIS sensor were used as input data in species distribution models. The SDM allowed the construction of monthly fire probability models for the study area. The model's quality was assessed by R-squared, RMSE, AUC and TSS metrics. In addition, we assessed the weight of variables in building the models. To obtain the fire seasonality, we used the bootstrap technique to calculate the 95% confidence interval (CI) about the mean. As result, we found that all algorithms obtained satisfactory performance, as well as the ensemble model technique used, which obtained an average AUC of 0.812 ± 0.001. The algorithm with the best individual performance was Random Forest, with a mean AUC 0.851 ± 0.002. Similar patterns were found when considering TSS metrics. The predicted and observed fire occurrences showed strong association (R2 = 0.81). The high fire probability area was higher during the dry season (15304.37 ± 41.65), showing a significant difference (p-value ≤ 0.05) from the rainy season. The variables that most explained the fire occurrences along the CAT were 'Silt Fraction', 'Distance from Agriculture' and 'Maximum Temperature'. In addition, ‘Distance from Roads’, ‘Distance from Protected Areas’ and Elevation’ were relevant for the monthly models. Anthropogenic variables were more important during the dry season. The results demonstrate that SDMs can be adequately used in fire prediction. Protected areas have shown an important role in acting as a fire barrier. However, many of these areas are vulnerable, surrounded by high fire probabilities during the dry season, predominantly anthropic, putting the natural dynamics of fire in the region and the local biodiversity at risk. Our approach can be useful in environmental protection and monitoring, in addition to facilitating the understanding about the CAT ecological complexity and the high anthropogenic pressure happening there.

Non-linear growth models for tree species used for forest restoration in Brazilian Amazon Arc of Deforestation

The large amount of degraded areas and productive potential of the legal reserves in Brazil make restoration an environmental demand and a commercial opportunity. We modelled the diameter growth as a function of age of eight tree species in restoration plantations in the Brazilian Amazon. From 14 years of annual forest inventory data, for each species, we tested variations of logistic function: simple logistic, logistic with covariant (plant area at the time of planting), logistic with random effect, logistic with random effect and covariant. Amongst the studied species, Schizolobium parahyba var. amazonicum, Tectona grandis and Simarouba amara showed the highest growth rates while Cordia alliodora, Cedrela odorata and three species of the genus Handroanthus showed slower growth. The gains from using the covariant in modeling were small for both fixed and mixed-effect models. Gains from the inclusion of the random effect were substantial. Mixed-effect models had the best performance in modeling the growth of the species. Our results provide basis for a critical view of the criteria and possibilities for degraded areas restoration and management practices in legal reserves of the Amazon. An economic analysis is required to ensure the viability of these areas’ sustainable exploitation.

Effects of Climate Change on Hydrology in the Most Relevant Mining Basin in the Eastern Legal Amazon

The Itacaiúnas River basin, an important watershed for the mining sector in Brazil, has had 51% of its native forest area deforested in the last forty years. It is in the arc of deforestation of the Amazon. It has protected areas essential to local biodiversity maintenance, in addition to owning ore reserves. Here, we present the first study to assess the mean annual, seasonal, and spatialized hydrological processes, providing results on a detailed scale in the basin, including mining sites. We used five future projections of mean monthly temperature and daily precipitation as input to the MGB hydrological model to simulate how hydrological processes, such as evapotranspiration, water availability, and high flows, may change in the next 30 years. The future decrease in precipitation (−8%) and increase in temperature (10%) may strengthen the monsoon seasonal cycle and lengthen the dry month for evapotranspiration. Furthermore, some parts of the basin expect an increase in the high flows (8.1%) and a decrease in water availability (−93.6%). These results provide subsidies to develop adaptation strategies to ensure the viability of mining operations and safeguard the surrounding environment and communities.

New records and range extension of Euphractus sexcinctus (Linnaeus, 1758) (Cingulata, Chlamyphoridae) in Rondônia state, Brazil

We report two new records of occurrence of Six-banded Armadillo, Euphractus sexcinctus (Linnaeus, 1758), in the state of Rondônia, Brazil, based on roadkills. These new records extend the geographic distribution of this species by 70 km. The records are from the region with a high deforestation rate called the “Arc of Deforestation”, which includes the state of Rondônia. Euphractus sexcinctus was recorded in an area with a high loss of vegetation cover, where the forest is being converted to pasture.

Contribution of rural settlements to the deforestation dynamics in the Legal Amazon

Rural settlements aim to promote land distribution in Brazil, as well as to apply agrarian policy. More than 9 thousand settlements in the country are distributed by the National Institute of Colonization and Agrarian Reform (INCRA), totaling 87.9 million hectares. Approximately 87% of this area is located in the Legal Amazon, an area of vital environmental and political importance in Brazil. This study evaluated the contribution of agrarian reform through the redistribution of land, the process of native vegetation suppression, and deforestation dynamics in the Legal Amazon. In addition, possible influences caused by modality, location within the Deforestation Arc, and the year of creation were also evaluated. The main results of the research show that there was a reduction in deforested areas in the settlements between the two periods analyzed and that the annual rate of deforestation within the settlements influences deforestation in the Legal Amazon. In addition, the study pointed out the "Conventional" category as the one that most converted the forest to other uses, showing the need to encourage sustainable land use. It is concluded that, for deforestation that occurs in settled areas, the greatest concentration of areas is located outside of the Deforestation Arc, which justifies why deforestation outside the Arc is greater when compared to settlements inserted in it. Regarding the creation year, deforestation is independent of this factor. However, after the insertion of the settlement, deforestation is intensified.

The “New Transamazonian Highway”: BR-319 and Its Current Environmental Degradation

The Brazilian government intends to complete the paving of the BR-319 highway, which connects Porto Velho in the deforestation arc region with Manaus in the middle of the Amazon Forest. This paving is being planned despite environmental legislation, and there is concern that its effectiveness will cause additional deforestation, threatening large portions of forest, conservation units (CUs), and indigenous lands (ILs) in the surrounding areas. In this study, we evaluated environmental degradation along the BR-319 highway from 2008 to 2020 and verified whether highway maintenance has contributed to deforestation. For this purpose, we created a 20 km buffer adjacent to the BR-319 highway and evaluated variables extracted from remote sensing information between 2008 and 2020. Fire foci, burned areas, and rainfall data were used to calculate a drought index using statistical tests for a time series. Furthermore, these were related to data on deforestation, CUs, and ILs using principal component analysis and Pearson’s correlation. Our results showed that 743 km2 of forest was deforested during the period evaluated, most of which occurred in the last four years. A total of 16,472 fire foci were identified. Both deforestation and fire foci occurred mainly outside the CUs and ILs. The most affected areas were close to capital cities, and after resuming road maintenance in 2015, deforestation increased outside the capital cities. Current government policy for Amazon occupation promotes deforestation and will compromise Brazil’s climate goals of reducing greenhouse gas (GHG) emissions and deforestation.

Cyperaceae in Serra dos Martírios-Andorinhas, Pará, Brazil

Abstract This study focuses on the Cyperaceae occurring in the Serra dos Martírios-Andorinhas (Serra dos Martírios- Andorinhas State Park, and São Geraldo do Araguaia Environmental Protection Area), in the São Geraldo do Araguaia municipality, state of Pará, Brazil. The Serra is in the “Deforestation Arc”, an environmentally vulnerable area with the highest deforestation rates in the Amazon Forest. The predominant phytophysiognomy is the Amazonian savanna, characterized by open environments dominated by herbaceous plants, such as Cyperaceae, represented by only four species in a previous floristic inventory. Studying the diversity of Cyperaceae allows us to a better understanding of the herbaceous layer’s dynamics and assisting in the conservation, monitoring, and management of these fascinating and peculiar environments. Therefore, 276 field and herbarium samples of Cyperaceae from Serra dos Martírios-Andorinhas were examined. Now, Cyperaceae are represented by 12 genera and 72 species in the study area, of which seven represent new records for the State of Pará. A taxonomic identification key, short descriptions with main diagnostic characters, geographic distribution, habitat data, and illustrations for all species and genera are provided.

Environmental vulnerability assessment of Brazilian Amazon Indigenous Lands

Amazonian Indigenous Lands (ILs) are human-environment systems facing a multitude of environmental threats. Yet, the resulting vulnerability of these systems are to date unknown. We adopt the theoretical vulnerability framework of the IPCC to assess the environmental vulnerability of Brazilian Amazon ILs for two periods (2001–2010 and 2011–2019) and overall (2001–2019). Vulnerability is deemed a function of exposure (EX), sensitivity (SE) and adaptive capacity (AC) of a system to threats. Sensitivity (threats within IL) and exposure (threats in IL’s buffer zones) indicators are changes in forest cover, economic activities, and road access, quantified using data of deforestation, forest degradation, land-use, fire, roads and mining. Adaptive capacity indicators represent Indigenous self-organization, education and access to knowledge, land ownership, external incomes, and institutional arrangement. We find a concentration of ILs with high vulnerability in the Arc of Deforestation and South, and advancing in Pará and Roraima states. A strong relationship (Spearman r = 0.79) between EX and SE indicates the strong pressure exerted by external processes. An increase in EX (73.9% of the ILs) and in SE (64.8% of the ILs) in 2011–2019 compared to 2001–2010 signals a worrying rise in vulnerability recently. We advise the adoption of policies by the State, such as combating illegal activities, and strengthening National Policy for Environmental and Territorial Management of ILs. Herein, our vulnerability quantification can prioritize help to certain ILs, and the understanding of the contribution of the underlying dimensions can direct these policies, possibly according to the vulnerability profile of each IL.

Mapping global forest age from forest inventories, biomass and climate data

Abstract. Forest age can determine the capacity of a forest to uptake carbon from the atmosphere. However, a lack of global diagnostics that reflect the forest stage and associated disturbance regimes hampers the quantification of age-related differences in forest carbon dynamics. This study provides a new global distribution of forest age circa 2010, estimated using a machine learning approach trained with more than 40 000 plots using forest inventory, biomass and climate data. First, an evaluation against the plot-level measurements of forest age reveals that the data-driven method has a relatively good predictive capacity of classifying old-growth vs. non-old-growth (precision = 0.81 and 0.99 for old-growth and non-old-growth, respectively) forests and estimating corresponding forest age estimates (NSE = 0.6 – Nash–Sutcliffe efficiency – and RMSE = 50 years – root-mean-square error). However, there are systematic biases of overestimation in young- and underestimation in old-forest stands, respectively. Globally, we find a large variability in forest age with the old-growth forests in the tropical regions of Amazon and Congo, young forests in China, and intermediate stands in Europe. Furthermore, we find that the regions with high rates of deforestation or forest degradation (e.g. the arc of deforestation in the Amazon) are composed mainly of younger stands. Assessment of forest age in the climate space shows that the old forests are either in cold and dry regions or warm and wet regions, while young–intermediate forests span a large climatic gradient. Finally, comparing the presented forest age estimates with a series of regional products reveals differences rooted in different approaches and different in situ observations and global-scale products. Despite showing robustness in cross-validation results, additional methodological insights on further developments should as much as possible harmonize data across the different approaches. The forest age dataset presented here provides additional insights into the global distribution of forest age to better understand the global dynamics in the forest water and carbon cycles. The forest age datasets are openly available at https://doi.org/10.17871/ForestAgeBGI.2021 (Besnard et al., 2021).

Landscape analysis in a municipality in the arc of deforestation of the Brazilian Amazon rainforest

The fight for the conservation of the Amazon region is anything but recent. Despite being one of the highest biodiversity assets in the world, it has undergone intense transformations of the landscape since the beginning of the anthropic “invasion” occupation. Changes in land use and occupation are observed for the municipality of Dom Eliseu, located in the zone characterized as the Arc of Deforestation. Given this premise, we designed this study to provide a quantitative understanding of forest fragmentation in the municipality of Dom Eliseu – PA. For this, cloud-free images from the TM (Landsat 5) and OLI (Landsat 8) sensors for 2008 and 2018 were used, respectively, for supervised classification of land use and land cover to identify the forest areas in the study area. The areas of each fragment were quantified and grouped into size classes, considering as very small (<5 ha), small (5–10 ha), medium (10–100 ha), and large (> 100 ha) fragments. The indexes used were area, edge, density and size, shape, and central. In total, 33,171 forest fragments were found in 2008, reduced to 32,385 in 2018, representing 42.71% of the forest cover area under study. Quantitative characterizations were made with groups of area indexes density and size, shape, and central area, the latter obtained for the distance of 100 m under edge effect. The area mapping infers that the forest fragments in the area are mainly found by very small fragments, smaller than 5 ha, indicating a high degree of forest fragmentation in this landscape during the two years under study.

Anthropogenic climate change contribution to wildfire-prone weather conditions in the Cerrado and Arc of deforestation

2015 saw the strongest El Niño event in the historical record, resulting in extreme drought conditions in Brazil. As drought conditions may also lead to greater fire danger, this study uses the 2015 fire in Brazil as a case study to examine whether and to what extent human-induced climate change has contributed to the fire weather conditions in the Cerrado and the southern Amazonia transitional forests known as the Arc of deforestation. Our results show that anthropogenic climate change is indeed a driver of meteorological conditions conducive to strong fire weather in these two regions, measured by fire weather index (FWI), especially on shorter timescales of daily and weekly. The anthropogenic climate change signal of FWI on short timescales corresponds to a similar order of increase in the FWI sub-indices (initial spread index and fine fuel moisture code) that can rapidly change due to the influence of the instantaneous weather conditions. For both regions the changes in fire weather in response to anthropogenic climate change are dominated by the combination of temperature and relative humidity responses. High FWI is more likely to occur under El Niño conditions, less likely under La Niña conditions, although the impacts of El Niño vs La Niña conditions are not symmetric when compared with El Niño Southern Oscillation neutral states. To summarize, both human-induced climate change and the presence of El Niño increased the likelihood of occurrence for the strong fire weather condition in 2015. Our results suggest that local and regional adaptation measures, such as improved drought monitoring and warning systems, could help with effective planning of fire prevention, firefighting actions, and disaster preparedness.

ENSAMBLE DE LA HERPETOFAUNA EN LA REGIÓN ENDÉMICA DE BELÉM, ESTADO DE PARÁ, ESTE DEL AMAZONAS, BRASIL

We present a list of amphibians and reptiles collected during six field surveys in the municipalities of Tailândia, Tomé-Açu and Moju, region of the Belém area of endemism, eastern Amazonia, Brazil. We conducted surveys on several fragments of the Amazon rainforest located in a matrix of palm oil plantations (Elaeis guineensis) and/or old pastures recently removed for new plantations. A total of 108 species, including amphibians (50), turtles (3), crocodiles (2), amphisbaenians (3), lizards (22) and snakes (28) were identified. Our results show a phylogenetic pattern already known for the Amazon, with Hylidae and Leptodactylidae presenting higher species richness among amphibians, Gymnophthalmidae and Teiidae for lizards, and Dipsadidae and Colubridae among snakes. Despite the study areas being inserted within the "arc of deforestation" in northeastern Pará state, where fragmented forest can be found in a matrix of palm oil plantations, pastures and regenerating forests, it still harbors a high diversity of reptiles and amphibians. Large-scale, agribusiness palm oil plantations are expanding in the region, and actions are needed to minimize impacts on local fauna. For this, conservation efforts focused on the remaining fragments of forest are crucial to protect the high species diversity still found in the region.

An integrative analysis uncovers a new, pseudo-cryptic species of Amazonian marmoset (Primates: Callitrichidae: Mico) from the arc of deforestation

Amazonia has the richest primate fauna in the world. Nonetheless, the diversity and distribution of Amazonian primates remain little known and the scarcity of baseline data challenges their conservation. These challenges are especially acute in the Amazonian arc of deforestation, the 2500 km long southern edge of the Amazonian biome that is rapidly being deforested and converted to agricultural and pastoral landscapes. Amazonian marmosets of the genus Mico are little known endemics of this region and therefore a priority for research and conservation efforts. However, even nascent conservation efforts are hampered by taxonomic uncertainties in this group, such as the existence of a potentially new species from the Juruena–Teles Pires interfluve hidden within the M. emiliae epithet. Here we test if these marmosets belong to a distinct species using new morphological, phylogenomic, and geographic distribution data analysed within an integrative taxonomic framework. We discovered a new, pseudo-cryptic Mico species hidden within the epithet M. emiliae, here described and named after Horacio Schneider, the pioneer of molecular phylogenetics of Neotropical primates. We also clarify the distribution, evolutionary and morphological relationships of four other Mico species, bridging Linnean, Wallacean, and Darwinian shortfalls in the conservation of primates in the Amazonian arc of deforestation.

Atmospheric moisture contribution to the growing season in the Amazon arc of deforestation

The Amazon moisture recycling system has been widely examined because it is fundamental to maintain some of the global climate processes, however, we have yet to know to what extent the agricultural growing season is dependent on the evapotranspiration contribution from the Amazon forest. Here we use a moisture tracking model to calculate the forest’s contribution to downwind precipitation. Specifically, we calculate the influence of moisture recycling on the seasonality of precipitation in the arc of deforestation with respect to the agricultural growing season. We calculated the wet season start, end and length using three scenarios (a) total precipitation with existing vegetation cover; (b) where we replace forest’s contribution to precipitation by replacing it with the equivalent from short vegetation; (c) where the forest’s contribution to precipitation is completely removed. We found that forest moisture recycling contributes up to 40% of monthly precipitation in the arc of deforestation. However, there is a strong spatial gradient in the forest’s contribution to precipitation, which decreases from west to east. This gradient also coincides with suitability for double-cropping agriculture. Our scenarios excluding precipitation originating from forest indicated that forest is a key contributing factor in determining the wet season start. We found that even when the precipitation originating from forest was replaced by short vegetation there was a significant delay in the wet season start in our study regions. Interestingly the wet season end was more resilient to changes in precipitation source. However it is clear that moisture recycling plays a key role in determining the wet season end as when forest’s contribution to precipitation was entirely removed the wet season end arrived significantly earlier. These differences in wet season length were not detectable in the eastern states of Tocantins and Maranhão, as much less of the precipitation in these states originates from the forest. Our findings demonstrate the importance of forest in supporting double-cropping agriculture in the arc of deforestation. As agricultural intensification by double-cropping increases land-use efficiency, it may also reduce the demand for further deforestation. Therefore it is important to identify how the current forest extent provides this important ecosystem service.

Putting fire on the map of Brazilian savanna ecoregions

The Brazilian savanna (Cerrado) is considered the most floristically diverse savanna in the world, home to more than seven thousand species. The region is a mosaic of savannas, grasslands and forests whose unique biophysical and landscape attributes are on the basis of a recent ecoregional map, paving the way to improved region-based strategies for land management actions. However, as a fire-prone ecosystem, Cerrado owes much of its distribution and ecological properties to the fire regime and contributes to an important parcel of South America burned area. Accordingly, any attempt to use ecoregion geography as a guide for management strategies should take fire into account, as an essential variable. The main aim of this study is to complement the ecoregional map of the Cerrado with information related to the fire component. Using remotely sensed information, we identify patterns and trends of fire frequency, intensity, seasonality, extent and scar size, and combine this information for each ecoregion, relying on a simple classification that summarizes the main fire characteristics over the last two decades. Results show a marked north-south fire activity gradient, with increased contributions from MATOPIBA, the latest agricultural frontier. Five ecoregions alone account for two thirds of yearly burned area. More intense fires are found in the Arc of Deforestation and eastern ecoregions, while ecoregions in MATOPIBA display decreasing fire intensity. An innovative analysis of fire scars stratified by size class shows that infrequent large fires are responsible for the majority of burned area. These large fires display positive trends over many ecoregions, whereas smaller fires, albeit more frequent, have been decreasing in number. The final fire classification scheme shows well defined spatially-aggregated groups, where trends are found to be the key factor to evaluate fire within their regional contexts. Results presented here provide new insights to improve fire management strategies under a changing climate.

Land-use effects on mosquito biodiversity and potential arbovirus emergence in the Southern Amazon, Brazil.

The Amazon rainforest is considered the largest reservoir of culicids and arboviruses in the world. It has been under intense human-driven alteration, especially in the so-called 'Arc of Deforestation', located in the eastern and southern regions. The emergence and transmission of infectious diseases are increasing, potentially due to land-use change. We used landscape-scale mosquito surveillance across a forest fragmentation gradient in the southern Amazon to evaluate the relationship between forest disturbance and the composition and structure of mosquito communities with a particular focus on the potential for arbovirus emergence in the region. Generalized linear models and logistic regression were used to associate the degree of landscape disturbance with arbovirus vectors' richness and abundance. A total of 1,960 culicids, belonging to 50 species, were collected from 2015 to 2016. Among these species, 20 have been associated with the transmission of arboviruses. Our results show an association of land use, more specifically small size of forest remnants with more irregular shape and higher edge density, with the increase of arbovirus vectors' richness and abundance. Six species of mosquito vectors exhibited a higher probability of occurrence in landscapes with medium or high degrees of disturbance. Our results indicate that land-use change influences mosquito communities with potential implications for the emergence of arboviruses.

Deforestation drivers in the Brazilian Amazon: assessing new spatial predictors

Researches on the deforestation of the Amazon have gained prominence in the last recent years, mainly with the change in the policy regarding the facing of this phenomenon by the Brazilian government. Therefore, an understanding about the causes that pressure the occurrence of deforestation remains relevant and has a leading role in the world. Therefore, the aim of this study is to perform the analysis of the spatial variability of the reasons for the deforestation in the Amazon Biome, in Brazil, (2010–2019). To achieve this goal, 14 variables were selected, the choice and adjustment of the regression model were determined and a diagnosis was carried out in order to verify the most appropriate model. To achieve this purpose, a geographic database was structured in a geographic information system environment. The main results revealed that the adjusted R2 of the Geographically Weighted Regression (GWR) was 0.96, that is, the GWR model explains 96% of the variations in deforestation. Therefore, it was observed a significant gain when using this model. In addition, it was also observed that the average variable of the number of oxen was, among those analyzed, the one that showed the highest correlation with deforestation. Thus, it was found that the livestock sector in southern Amazonia is the main economic agent that pressures large areas of deforestation, since stockfarming is practiced extensively. Finally, it was concluded that the municipalities with the largest areas of deforestation formed a cluster in the southern portion of the Amazon, in the arc of deforestation.