Central Amazon Research Articles

Water Typology in the Amazon: Close Correlation with the Hydrogeochemistry of River Basins

A study on the typology of Amazonian waters was developed in the North Geographic Region of Brazil, considering a set of historical data from 1995 to 2022. The objective was to discuss and point out which environmental parameters are considered preponderant within the classification criteria of Amazonian waters. Historical data on temperature, density, pH, conductivity, oxygen, transparency, light attenuation, turbidity, color, total and dissolved solids, hardness, alkalinity, CaCO3, BOD, COD, main cations and anions, iron, C, N and P fractions, silicate, trace elements (Al, Cu, Zn and Mn) and chlorophyll a were analyzed. The analysis comprised water samples from the National Hydrometeorological Network (Sub-Basins 10 to 19), with a total of 36 basins, including tributaries, lakes and adjacent streams. The historical series was statistically analyzed through the techniques of Cluster, Principal component analysis (PCA), Piper Diagram and image interpolation by the ordinary kriging method. The results indicated a strong seasonal trend, with an evident distinction between the flood and ebb periods. The typology of white, black and clear waters was also evidenced, this last group being an intermediate class to the others, due to the physical-chemical standards. The PCA highlighted the parameters conductivity, pH, calcium, bicarbonate and Dissolved inorganic carbon (DIC) (Factor 1), and turbidity and alkalinity (Factor 2) as preponderant in the water classification. The ionic balance demonstrated that the white waters stood out for the highest concentrations of calcium and magnesium. The results suggest a pattern of calcic waters oscillating towards sodic and carbonated waters, with a subgroup in the northern eastern region of seasonally sodic-chlorinated waters, due to the influence of ocean tides. Image interpolation suggested a predominance of white waters in the western southern zone (Western Amazon) and white waters transitioning to clear waters in the eastern zone (Eastern Amazon). The analysis also showed a predominant strip of black and clear waters in the northern zone, and a strip of white waters in the central Amazon.

Beta diversity and microhabitat use of ant assemblages in a white-sand vegetation gradient in central Amazonia

Beta diversity and microhabitat use of ant assemblages in a white-sand vegetation gradient in central Amazonia

Reevaluation of Rhipidomys emiliae (J.A. Allen 1916) and description of a new Rhipidomys (Rodentia: Cricetidae) species from Amazonia and Cerrado.

We present the revalidation of the sigmodontinae rodent species R. emiliae, as well as the description of a new species for the genus Rhipidomys. The maximum likelihood analysis recovers R. emiliae as sister species of the clade with Rhipidomys sp. nov. and R. ipukensis, with high bootstrap values. Comparisons between these species based on the external, cranial, and dental morphology identified several unique characters in Rhipidomys sp. nov., including more grayish brown color of the dorsal coat, subsquamosal fenestra wide and long, angular process ends in the same position of the end of condyloid process, conspicuous protostyle and enterostyle. We describe a new karyotype (2n = 44 and FN = 64) for the genus and, based on an integrative analysis together with morphology and molecular phylogeny, assign it to R. emiliae, and assign the karyotype with 2n = 44 and FN = 52 to Rhipidomys sp. nov.. The analysis integrating data indicated that R. emiliae has a geographic distribution restricted to the lowlands of eastern Amazonia, whereas Rhipidomys sp. nov. occurs in the central Amazonia and Cerrado. The data showed that some Rhipidomys species have its distribution currently limited by rivers, as Rhipidomys sp. nov. occurring west of the Araguaia-Tocantins interfluve, R. emiliae east of the Tocantins River, and R. ipukensis between the Tocantins and Araguaia rivers. This work, in addition to revealing a still unknown biodiversity describing a species, brings a new understanding to the genus, and shows how integrating different markers helps in the correct association between the nominal form and the karyotype.

Canopy gaps and associated losses of biomass – combining UAV imagery and field data in a central Amazon forest

Abstract. Understanding mechanisms of tree mortality and the dynamics of associated canopy gaps is relevant for robust estimates of carbon balance in forests. We combined monthly RGB images acquired from an unoccupied aerial vehicle with field surveys to identify gaps in an 18 ha plot installed in an old-growth central Amazon forest. We measured the size and shape of gaps and analyzed their temporal variation and correlation with rainfall over a period of 28 months. We further described associated modes of tree mortality (i.e., snapping, uprooting and standing dead) and branch fall and quantified associated losses of biomass. In total, we detected 32 gaps either in the images or field ranging in area from 9 to 835 m2. Relatively small gaps (< 39 m2) opened by branch fall were the most frequent (11 gaps). Out of 18 gaps for which both field and image data were available, three could not be detected remotely. Gaps observed in the field but not captured on the imagery were relatively small and mainly formed by the fall of branches from live and standing dead trees. Our data show that ∼ 17 % of the tree-mortality and branch-fall events only affected the lower canopy and the understory of the forest and are likely neglected by top-of-the-canopy assessments. Regardless of the detection method, the size distribution was best described by a lognormal function for gaps starting from the smallest detected size (9 and 10 m2 for field and imagery data, respectively), and the Weibull and Power functions for gaps larger than 25 m2. Properly assessing associated confidence intervals requires larger sample sizes. Repeated field measurements reveal that gap area does not differ significantly among modes of tree mortality or branch fall in central Amazon forests, with the last contributing the least to biomass loss. Predicting mechanisms of gap formation based on associated area and biomass loss remains challenging, which highlights the need for larger datasets. The rate of gap area formation was positively correlated with the frequency of extreme rainfall events, which may be related to a higher frequency of storms propagating extreme rain and wind gusts. While remote sensing has proven to be an accurate and precise method for mapping gaps compared to field data (i.e., ground truth), it is important to note that our sample size was relatively small. Therefore, the extrapolation of these results beyond our study region and landscape shall be made cautiously. Apart from improving landscape assessments of carbon balance, regional information on gap dynamics and associated mechanisms of formation are fundamental to address forest responses to altered disturbance regimes resulting from climate change.

Effects of the river breeze on the transport of gases in Central Amazonia

River breezes occur regularly along the Amazonia river but little is known about their effects on air pollution. During the first week of August 2014, river breeze events were observed on two days on the banks of the Negro River, central Amazonia. The WRF-Chem model was used to analyze this period to understand the formation mechanism and the influence of the river breeze on the transport of pollutants such as ozone (O3) and carbon monoxide (CO). We show that the river breeze occurred due to a reduction of the easterly winds associated with the cooling of the waters of the Negro River. The river breeze was responsible for inhibiting the transport of pollutants to the East, increasing its concentrations while breeze circulation is observed, as well as a re-circulation of these gases on the riverbank where the breeze was associated. The strongest breeze occurred in a forest region which maintained the highest concentrations of CO and O3 on the East bank of the Negro River. In the Urban region, the breeze was less intense and had a shorter duration, however, it was still able to maintain higher concentrations of CO and O3 in the western region of the city of Manaus, which is a predominantly residential region and therefore, the population of this region lives in a more polluted environment during the occurrence of breezes.

Expressive fluxes over Amazon floodplain revealed by 2D hydrodynamic modelling

Water fluxes in the Amazon River floodplain affect hydrodynamic and ecological processes from local to global scales, but they remain poorly understood due to difficult accessibility and limited data. We characterized the hydrodynamics of eight floodplain units of the central Amazon River (40000 km2) using the 2D hydraulic model HEC-RAS. High resolution modelling (∼400 m) improved the representation of river and floodplain discharge, water surface elevation (77 cm accuracy) and flood extent (∼80% - high water period, ∼52% - low water period) compared to past modelling studies. Our results show that floodplain flows during floods are very intense with upstream inflow and downstream outflow of the floodplain units. These gross flows are much larger than the net flows, with values of up to 20% of the Amazon River discharge and residence time around 6 days during floods (several months during low water period). Water extent did not show strong interannual variability during floods as the volume stored in the floodplain did, possibly due to topographic constraints. Significant hysteresis in flood extent and volume, and active and storage zones on the floodplain highlight the complexity of floodplain hydrodynamics. Extreme floods strongly impacted the onset and duration of the flood by up to one month and, consequently on duration of high water renewal period with the river. Our characterization is important to assess the effects of extreme floods on riverine communities, understand nutrient and sediment variations in the floodplain, and characterize the export of water, sediment, and carbon flux to the ocean from the world's largest hydrological system.

Kleptoparasitism attempt on a greater grison (Galictis vittata) by a white hawk (Pseudastur albicollis) in the Brazilian Amazon

ABSTRACT Facultative kleptoparasites face the risk of trying to steal food resources from competitors. This type of interaction is little known, but anecdotal observations indicate that birds of prey may take advantage of their accurate sight to detect the best opportunities for kleptoparasitism. We recorded a camera trap video of an attempt of kleptoparasitism by the white hawk, Pseudastur albicollis, that tried to steal food from a greater grison, Galictis vittata, in a recently selectively-logged forest site in central Brazilian Amazonia. The attempt was unsuccessful as the greater grison responded aggressively to the attack. The event occurred in a linear clearing, which may have increased the bird’s ability to detect its potential host. Kleptoparasitic interactions are difficult to detect in forest environments. Recording opportunistic kleptoparasitic interactions in tropical forests may not only depend on the increasing use of camera traps, but also on habitat conditions that facilitate the detection of potential hosts.

Cultural aspects for adaptation to the climate change impacts on the Ecosystem Services in a case study of Central Amazon

Climate adaptation tends to face resistance or produce adverse effects, if it is tested only on the generalist scientific models, ignoring its effects on the culture, values, and worldviews of local communities. This article investigates how climate change has threatened the livelihood and cultural dimensions of peri-urban communities in the Central Amazon. The analysis is based on the cultural theory of risk in climate adaptation and its relationships to local Ecosystem Services (ES). In this case study, semi-structured interviews were conducted with residents of three municipalities in the Metropolitan Area of Manaus-Brazil. Given that their diet used to be heavily based on native food, the results show how Amazonian communities are adapting their eating habits in response to climate and environmental changes to the ES decline in the category of food security (i.e., in the class of provisioning ES). In addition, these services have relevant cultural value (i.e., cultural services). The ES reduction influences adaptation strategies amid the dismantling of current environmental policies. As a result, these communities began to adopt industrialized means of production and consumption, such as adopting products derived from cattle, whose production is the main cause of greenhouse gas emissions in Brazil. Therefore, the studied case demonstrates how climate adaptation may pressure and erode local cultures, when these following the logic of globalized urbanization.

Conservation implications of tourism and stress for Amazonian caimans

AbstractEcotourism is a strategy for biodiversity conservation, but it involves possible negative effects on animal health and welfare. Large predators such as crocodilians are one of the great public attractions sought after for tourist interactions. Interactions with wild animals and humans can hyperstimulate the hypothalamic‐pituitary‐adrenal axis in the short term, in the case of crocodilians showing an increased corticosterone level, which is indicative of physiological stress. Between September and December 2019, we simulated interactions between tourists and Amazonian crocodilians at Anavilhanas National Park in Central Amazonia, Brazil to evaluate the effects of handling and use of photographic flashes on black caiman (Melanosuchus niger) and spectacled caiman (Caiman crocodilus) on circulating corticosterone and lactate. Corticosterone levels increased 1.7‐fold during handling and 2.7‐fold when exposed to photographic flashes in black caiman but not in spectacled caiman. Increased corticosterone concentrations in black caiman were characterized by an increase caused by handling and were more intense after flashes than in controls, but the combination of handling and flash had no effect. During handling in simulated tourist interactions, anaerobic respiration increased lactate in black caiman but not in spectacled caiman. The effect of simulated tourist interactions with Amazonian crocodilians was dependent on the handling and especially on flash use in black caiman. The results can assist management, conservation programs, and public policies, especially in programs based on tourism interaction with Amazonian crocodilians.

Sensitivity of Optical Satellites to Estimate Windthrow Tree-Mortality in a Central Amazon Forest

Windthrow (i.e., trees broken and uprooted by wind) is a major natural disturbance in Amazon forests. Images from medium-resolution optical satellites combined with extensive field data have allowed researchers to assess patterns of windthrow tree-mortality and to monitor forest recovery over decades of succession in different regions. Although satellites with high spatial-resolution have become available in the last decade, they have not yet been employed for the quantification of windthrow tree-mortality. Here, we address how increasing the spatial resolution of satellites affects plot-to-landscape estimates of windthrow tree-mortality. We combined forest inventory data with Landsat 8 (30 m pixel), Sentinel 2 (10 m), and WorldView 2 (2 m) imagery over an old-growth forest in the Central Amazon that was disturbed by a single windthrow event in November 2015. Remote sensing estimates of windthrow tree-mortality were produced from Spectral Mixture Analysis and evaluated with forest inventory data (i.e., ground true) by using Generalized Linear Models. Field measured windthrow tree-mortality (3 transects and 30 subplots) crossing the entire disturbance gradient was 26.9 ± 11.1% (mean ± 95% CI). Although the three satellites produced reliable and statistically similar estimates (from 26.5% to 30.3%, p < 0.001), Landsat 8 had the most accurate results and efficiently captured field-observed variations in windthrow tree-mortality across the entire gradient of disturbance (Sentinel 2 and WorldView 2 produced the second and third best results, respectively). As expected, mean-associated uncertainties decreased systematically with increasing spatial resolution (i.e., from Landsat 8 to Sentinel 2 and WorldView 2). However, the overall quality of model fits showed the opposite pattern. We suggest that this reflects the influence of a relatively minor disturbance, such as defoliation and crown damage, and the fast growth of natural regeneration, which were not measured in the field nor can be captured by coarser resolution imagery. Our results validate the reliability of Landsat imagery for assessing plot-to-landscape patterns of windthrow tree-mortality in dense and heterogeneous tropical forests. Satellites with high spatial resolution can improve estimates of windthrow severity by allowing the quantification of crown damage and mortality of lower canopy and understory trees. However, this requires the validation of remote sensing metrics using field data at compatible scales.

Aerial insectivorous bat responses to 30 years of forest insularization in a dam-created Amazonian archipelagic landscape

Mega dams result in habitat loss and fragmentation in lowland tropical forests, compromising the diversity and ecosystem functioning in remnant habitat islands. We investigated the structure of aerial insectivorous bat assemblages within insular forest patches created by a vast ∼30-year-old hydropower reservoir and adjacent mainland continuous forests in Central Amazonia. Bats were surveyed using passive bat recorders across 34 sites. We assessed bat assemblage responses to landscape insularization and estimated the contribution of assemblage-wide components of β-diversity. Additionally, we assessed the effects of local vegetation, and both patch and landscape variables on bat species diversity. Continuous forest sites in the mainland retained higher species richness and bat activity compared to islands, leading to divergent species composition between forest sites. Larger islands (>100 ha) and continuous forests tended to share a similar assemblage composition manly drive by species richness differences with a minor contribution of species replacements. Moreover, local vegetation structure, island size, and landscape edge area exerted significant effects on species richness, bat activity, and species composition, with small degraded islands and landscapes dominated by forest edges exhibiting pervasive species loss. Our study highlights the detrimental impacts of forest fragmentation induced by large dams on aerial insectivorous bat assemblages. If new dam projects are inevitable, we recommend the creation of extensive protected areas in land-bridge island systems and their adjacent continuous forests. Those protected sites can minimize the negative impacts of small islands, safeguarding forest quality for forest-dependent bats, which ensures the continuity of their ecosystem services.

The First Mitochondrial Genome of an Odonata Endemic to South America, Chalcopteryx rutilans (Rambur, 1842) (Odonata: Polythoridae), and Its Implications for the Phylogeny of the Zygoptera

Chalcopteryx rutilans Rambur, 1842 (Polythoridae, Odonata) is a species widely distributed in central Amazonia. Due to its sensitivity to environmental changes, it is a bioindicator species used to evaluate the environmental conditions of streams in federally protected areas. By sequencing C. rutilans mitogenome, we report the first whole mitogenome from the Polythoridae family and the first from an Odonata species endemic to South America. The entire mitogenome has 15,653 bp and contains 13 protein-coding, 22 tRNA, and two rRNA genes. The nucleotide composition of the mitogenome is 42.7%, T: 25.5%, C: 19.4%, and G: 12.4%. The AT and GC skews of the mitogenome sequence were 0.249 and −0.220, respectively. C. rutilans was recovered as a sister to Pseudolestes mirabilis Kirby, 1900 (Pseudolestidae), demonstrating the absence of mitogenomes of species from multiple families in the current literature. Mitogenome data from this study will provide useful information for further studies on the phylogeny and conservation of Polythoridae.

Livelihood alterations and Indigenous Innovators in the Ecuadorian Amazon

This article approaches livelihood alterations in Indigenous communities of the Ecuadorian Amazon as means of adaptation and resistance to socio-environmental impacts brought along by the expansion of global capitalism. The cases comprise collective Indigenous endeavors in typically capitalist sectors - tourism and mining - illustrated by the experiences of Kichwa community tourism in Shiripuno in the central Amazon, and sustainable mining in the southern Amazonian Shuar community of Congüime (Kenkuim). The aim is to unravel these emerging livelihood strategies in relation to Indigenous ethno-cultural identity. Methodologically, we rely on comparative and ethnographic work in the field with Indigenous actors, and on a theoretical framework anchored in the concepts of innovators, cultural boundary changes (Fredrik Barth), social fields of force (William Roseberry), and intercultural regimes (Fernando Galindo and Xavier Albó). In both empirical cases - Indigenous-controlled tourism and mining - communities are framing their ethnic identity to engage with, and positively reposition themselves in relation to the wider society. We hold that these endeavors must be comprehended as highly innovative, and that indigeneity and cultural boundaries can be strengthened by socio-cultural changes toward livelihoods previously considered as “unauthentic” or “non-Indigenous”. We also argue that these new livelihood orientations have (purposely) altered gender relations within the communities in benefit of women. Additionally, our cases suggest that cultural strengthening and gender empowerment, among other positive outcomes, requires a nuanced apprehension of indigeneity as a partly floating concept and instrument gaining ground amid the increasing interconnectedness of ancient traditions and capitalist modernity.

Intra- and interannual changes in isoprene emission from central Amazonia

Abstract. Isoprene emissions are a key component in biosphere–atmosphere interactions, and the most significant global source is the Amazon rainforest. However, intra- and interannual variations in biological and environmental factors that regulate isoprene emission from Amazonia are not well understood and, thereby, are poorly represented in models. Here, with datasets covering several years of measurements at the Amazon Tall Tower Observatory (ATTO) in central Amazonia, Brazil, we (1) quantified canopy profiles of isoprene mixing ratios across seasons of normal and anomalous years and related them to the main drivers of isoprene emission – solar radiation, temperature, and leaf phenology; (2) evaluated the effect of leaf age on the magnitude of the isoprene emission factor (Es) from different tree species and scaled up to canopy with intra- and interannual leaf age distribution derived by a phenocam; and (3) adapted the leaf age algorithm from the Model of Emissions of Gases and Aerosols from Nature (MEGAN) with observed changes in Es across leaf ages. Our results showed that the variability in isoprene mixing ratios was higher between seasons (max during the dry-to-wet transition seasons) than between years, with values from the extreme 2015 El Niño year not significantly higher than in normal years. In addition, model runs considering in situ observations of canopy Es and the modification on the leaf age algorithm with leaf-level observations of Es presented considerable improvements in the simulated isoprene flux. This shows that MEGAN estimates of isoprene emission can be improved when biological processes are mechanistically incorporated into the model.

Lumber yield of Sucupira-Vermelha in central Amazon sawmill

The sustainable use of forestry resources has an intrinsic relationship with log yield in sawmills, because the knowledge of this variable can optimize the processed wood production. Thus, the objective of this work was to determine the percentage yield in the sawing of Sucupira-Vermelha (Andira parviflora Ducke.) logs in different diameter classes and to adjust mathematical models to estimate processed wood. It was sampled 56 logs with diameters between 31 and 69 cm grouped into 4 diameter classes. Afterwards the sawing was performed obtaining various pieces of wood which were cubed to determine the yielding percentage. The increase in diameter classes provided an increase in sawn wood yield, which showed a significant difference only between the diameter class 1 and the others studied. Twelve mathematical models, 6 linear and 6 nonlinear, were evaluated. The models quality adjustment and selection was based on the highest adjusted determination coefficient (R²adj), lowest estimation standard error (Syx) and variation coefficient (VC%) and, most homogeneous residues graphic distribution. The nonlinear models of single entry (diameter) and double entry (diameter and length) were the most accurate to estimate the sawn wood yield of Sucupira-Vermelha species.

Seasonal distribution of Calliphoridae and Mesenbrinellidae (Diptera) associated with the decomposition of a clothed animal model in a forest reserve in the Central Amazon.

We evaluated the effects of seasonality on the richness and abundance of dipterans of the families Calliphoridae and Mesembrinellidae associated with the decomposition of a clothed Large White swine Sus scrofa domesticus(Artiodactyla: Suidae) carcass. Experiments were carried out in less rainy, rainy, and intermediate periods between 2010 and 2011 at Reserva Florestal Ducke, Manaus, Amazonas. Two pig carcasses, each weighing approximately 40 kg, were used in each period. A total of 63,872 individuals of 18 species of Calliphoridae and Mesembrinellidae were collected. The abundance and richness of these dipteran families were influenced by the interaction between period and decomposition stage. The compositions of the Calliphoridae and Mesembrinellidae assemblages differed among periods, with the fauna of the less rainy period being less similar to those of the intermediate and rainy periods than they were to each other. Three species were selected as indicators for the less rainy period, namely Paralucilia pseudolyrcea (Mello, 1969) (Diptera, Calliphoridae), Paralucilia nigrofacialis (Mello, 1969) (Diptera, Calliphoridae), and Eumesembrinella randa (Walker, 1849) (Diptera,Mesembrinellidae) while Chloroprocta idioidea (Robineau-Desvoidy, 1830) (Dipetra, Calliphoridae) was selected as an indicator species for the rainy period; no taxon was selected as an indicator of the intermediate period. Among decomposition stages, only fermentation and black putrefaction had indicator taxa, with Hemilucilia souzalopesi Mello, 1972 (Diptera, Calliphoridae and Chysomya putoria(Wiedemann, 1830) (Diptera, Calliphoridae), respectively. Clothes did not prevent the laying of eggs and became a kind of protection for immature stages. The clothed model presented a delay in decomposition compared to other studies developed in the Amazon region.

Anthropogenic factors do not affect male or female jaguar habitat use in an Amazonian Sustainable Reserve

Conservation actions should account for species natural history and behavior related to differences between sexes. However, most studies have not taken into consideration non-independence of observations from the same individual. We used data from camera-trap surveys undertaken over six consecutive years to investigate habitat use by jaguar (Panthera onca) in varzea seasonally flooded forest. We used hierarchical modeling to assess sex differences in occurrence probability related to environmental factors, while accounting for individual and spatial autocorrelation. Specifically, we tested whether male and female jaguars responded differently to habitat type and anthropogenic influence. Our results do not support previous conclusions related to differences between sexes and indicate that, in the studied area, jaguars are habitat generalists, exploring all environments with similar probability during the low-water season. Human settlements also apparently have little effect on habitat use by jaguars in this area. The lack of avoidance of settlements might be due to the low levels of anthropogenic pressure in the area, which adds support to the effectiveness of sustainable-development reserves. The difference between our results and previous studies may be due to the fact that we took into account individual differences, or may be related to the unique environmental characteristics of the varzea of Mamirauá Sustainable Development Reserve in Central Amazonia.

Optimizing survey effort for Euglossine bees in tropical forests

Optimizing research efforts for biodiversity monitoring is crucial to conservation projects and actions to increase our ability to inform conservation priorities. However, it requires the financial and human capacity. Euglossini bees have been used in monitoring actions as successful bioindicators. Yet, relationships among variables and stressors are complex and can change over time, environment, and local conditions. Here we investigated the influence of sample area on sampling to maximize the cost-benefit ratio of collection effort and the relationship from Euglossini bees with environmental predictors at a mesoscale (25 km2) in central Amazonia considering PPBio plots structure. We found differences considering the sampling unit scale, including capturing different assemblage species compositions. Most bee species were sampled along the phosphorus gradient. Due to the growth of deforestation in the Amazon Forest, especially in the so-called “Arc of Deforestation”, these bees could provide quick and valuable information about landscape quality. Here we present part of the pieces from a giant puzzle that we still need to complete to provide conservation efforts for this group. Our work highlighted the need to consider soil and nutrient variables other than vegetation and distribute scents traps in larger areas instead of in small plots.

Long-Term Measurements of the Atmospheric Boundary Layer Height in Central Amazonia Using Remote Sensing Instruments

The height (zi) of the Atmospheric Boundary Layer (ABL) is a fundamental parameter for several areas of knowledge, especially for weather and climate forecasting, pollutant dispersion and air quality. In this work, we used data from a remote sensing instrument (ceilometer), located at the experimental site of the Amazon Tall Tower Observatory (ATTO) in the Central Amazonia rainforest, in order to obtain the height of the ABL. Data used were obtained from 2014 to 2020, with the exception of the year 2017. The results showed that the zi average varies from year to year (interannual variability) and the average of the maximum zi values (zi_max) was approximately 1400 ± 277 m, occurring at 15:00 local time. In addition, it was found that these maximum heights are higher in the dry season and during El Niño years (about 1741 ± 242 m) and they are lower during the wet period and in La Niña years (1263 ± 229 m). Taking into account all the years investigated, the month with the highest zi_max value is September (1710 ± 253 m), and the month with the lowest value is May (1108 ± 152 m). Finally, it was observed that the growth rate of the ABL during the early hours after sunrise varies from month to month (intraseasonal variability), reaching its maximum values in September and October (about 210 ± 53 m h−1 and 217 ± 59 m h−1, respectively) and minimum values in April and July (approximately 159 ± 48 m h−1 and 159 ± 50 m h−1, respectively). It is concluded that the values of zi in Central Amazonia are influenced by several seasonal factors (temperature, cloud cover, turbulent heat flux, etc.) which gives it a wide variability in terms of heights and growth rates. Additionally, a linear regression was proposed in order to model the maximum zi value as a function of its growth rate from 08:00 LT (Local Time) up to 10:00 LT. The results showed a good correlation compared with the experimental values.

The climatic risk of Amazonian protected areas is driven by climate velocity until 2050.

Changes in species distribution in response to climate change might challenge the territorial boundaries of protected areas. Amazonia is one of the global regions most at risk of developing long distances between current and future analogous climates and the emergence of climate conditions without analogs in the past. As a result, species present within the network of Protected Areas (PAs) of Amazonia may be threatened throughout the 21st century. In this study, we investigated climate velocity based on future and past climate-analogs using forward and backward directions in the network of PAs of Amazonia, in order to assess the climatic risk of these areas to climate change and verify their effectiveness in maintaining the current climate conditions. Using current (1970-2000) and future (2041-2060) average annual air temperature and precipitation data with a resolution of 10 km, climate velocities across the entire Amazon biome and average climate velocities of PAs and Indigenous Lands (ILs) were evaluated. The results show that the effects of backward velocity will be greater than that of forward velocity in the Amazon biome. However, the PA network will be less exposed to backward velocity impacts than unprotected areas (UAs)-emphasizing the importance of these areas as a conservation tool. In contrast, for the forward velocity impacts, the PA network will be slightly more exposed than UAs-indicating that the current spatial arrangement of the PA network is still not the most suitable to minimize impacts of a possible climate redistribution. In addition, a large extent of no-analog climates for backward velocities was found in central Amazonia, indicating that high temperatures and changes in precipitation patterns in this region will surpass the historical variability of the entire biome, making it a potentially isolated and unsuitable climatic envelope for species in the future. Most of the no-analog climates are in PAs, however the climate risks in ILs should also be highlighted since they presented higher climate velocities than PAs in both metrics. Our projections contrast with the median latitudinal migration rate of 2 km/year observed in most ecosystems and taxonomic groups studied so far and suggest the need for median migration rates of 7.6 km/year. Thus, despite the important role of PAs and ILs as conservation tools, they are not immune to the effects of climate change and new management strategies, specific to each area and that allow adaptation to global changes, will be necessary.