Physical and chemical post-dam alterations in the Jamari River, a hydroelectric-developed river of the Brazilian Amazon

The regulation of the Jamari River advanced peak floods by 1–2 months and increased dry-season discharges from 60 to 200 m³ s^–1, resulting in water levels approximately 1 m above those recorded before regulation. Daily variation in water level associated with fluctuations in electricity production by the dam propagated to the lower reaches of the tributary Candeias River. Dissolved oxygen (DO), temperature, pH, and conductivity measured over 1.5 years on three locations along the regulated and two free-flowing rivers indicated important alterations in the case of oxygen concentrations. DO levels shifted from saturated (7–8 mg l^–1) during the flood season (when the spillways were open releasing epilimnetic water) to hypoxic (1.5–3 mg l^–1) during the dry season (when the floodgates were closed and only hypolimnetic water used to run the turbines was feeding the river). Fluctuations in water level and variation in dissolved oxygen tended to be greater at the site closest to the dam, gradually attenuating downstream. Mitigation of the downstream effects of river regulation would require modifications in the operation of the dam.     

Fire in the Brazilian Amazon

Regenerating forests have become a common land-cover type throughout the Brazilian Amazon. However, the potential for these systems to accumulate and store C and nutrients, and the fluxes resulting from them when they are cut, burned, and converted back to croplands and pastures have not been well quantified. In this study, we quantified pre- and post-fire pools of biomass, C, and nutrients, as well as the emissions of those elements, at a series of second- and third-growth forests located in the states of Pará and Rondônia, Brazil. Total aboveground biomass (TAGB) of second- and third-growth forests averaged 134 and 91 Mg ha^–1, respectively. Rates of aboveground biomass accumulation were rapid in these systems, but were not significantly different between second- and third-growth forests, ranging from 9 to 16 Mg ha^–1 year^–1. Residual pools of biomass originating from primary forest vegetation accounted for large portions of TAGB in both forest types and were primarily responsible for TAGB differences between the two forest types. In second-growth forests this pool (82 Mg ha^–1) represented 58% of TAGB, and in third-growth forests (40 Mg ha^–1) it represented 40% of TAGB. Amounts of TAGB consumed by burning of second- and third-growth forests averaged 70 and 53 Mg ha^–1, respectively. Aboveground pre-fire pools in second- and third-growth forests averaged 67 and 45 Mg C ha^–1, 821 and 707 kg N ha^–1, 441 and 341 kg P ha^–1, and 46 and 27 kg Ca ha^–1, respectively. While pre-fire pools of C, N, S and K were not significantly different between second- and third-growth forests, pools of both P and Ca were significantly higher in second-growth forests. This suggests that increasing land use has a negative impact on these elemental pools. Site losses of elements resulting from slashing and burning these sites were highly variable: losses of C ranged from 20 to 47 Mg ha^–1; N losses ranged from 306 to 709 kg ha^–1; Ca losses ranged from 10 to 145 kg ha^–1; and P losses ranged from 2 to 20 kg ha^–1. Elemental losses were controlled to a large extent by the relative distribution of elemental mass within biomass components of varying susceptibilities to combustion and the temperatures of volatilization of each element. Due to a relatively low temperature of volatilization and its concentration in highly combustible biomass pools, site losses of N averaged 70% of total pre-fire pools. In contrast, site losses of P and Ca resulting from burning were 33 and 20% of total pre-fire pools, respectively, as much of the mass of those elements was deposited on site as ash. Pre- and post-fire biomass and elemental pools of second- and third-growth forests, as well as the emissions from those systems, were intermediate between those of primary forests and pastures in the Brazilian Amazon. Overall, regenerating forests have the capacity to act as either large terrestrial sinks or sources of C and nutrients, depending on the course of land-use patterns within the Brazilian Amazon. Combining remote sensing techniques with field measures of aboveground C accumulation in regenerating forests and C fluxes from those forests when they are cut and burned, we estimate that during 1990–1991 roughly 104 Tg of C was accumulated by regenerating forests across the Brazilian Amazon. Further, we estimate that approximately 103 Tg of C was lost via the cutting and burning of regenerating forests across the Brazilian Amazon during this same period. Since average C accumulations (5.5 Mg ha^–1 year^–1) in regenerating forests were 19% of the C lost when such forests are cut and burned (29.3 Mg ha^–1), our results suggest that when less than 19% of the total area accounted for by secondary forests is cut and burned in a given year, those forests will be net accumulators of C during that year. Conversely, when more than 19% of regenerating forests are burned, those forests will be a net source of C to the atmosphere.     

Association between Knops blood group polymorphisms and susceptibility to malaria in an endemic area of the Brazilian Amazon

Complement receptor 1 (CR1) gene polymorphisms that are associated with Knops blood group antigens may influence the binding of Plasmodium parasites to erythrocytes, thereby affecting susceptibility to malaria. The aim of this study was to evaluate the genotype and allele and haplotype frequencies of single-nucleotide polymorphisms (SNPs) of Knops blood group antigens and examine their association with susceptibility to malaria in an endemic area of Brazil. One hundred and twenty-six individuals from the Brazilian Amazon were studied. The CR1-genomic fragment was amplified by PCR and six SNPs and haplotypes were identified after DNA sequence analysis. Allele and haplotype frequencies revealed that the Kn(b) allele and H8 haplotype were possibly associated with susceptibility to Plasmodium falciparum. The odds ratios were reasonably high, suggesting a potentially important association between two Knops blood antigens (Kn(b) and KAM(+)) that confer susceptibility to P. falciparum in individuals from the Brazilian Amazon.     

Soil carbon stocks and changes after oil palm introduction in the Brazilian Amazon

As oil palm has been considered one of the most favorable oilseeds for biodiesel production in Brazil, it is important to understand how cultivation of this perennial crop will affect the dynamics of soil organic carbon (SOC) in the long term. The aim of this study was to evaluate the changes in soil C stocks after the conversion of forest and pasture into oil palm production in the Amazon Region. Soil samples were collected in March 2008 and September 2009 in five areas: native forest (NARF), pasture cultivated for 55 years (PAST), and oil palm cultivated for 4 (OP‐4), 8 (OP‐8) and 25 years (OP‐25), respectively. Soils were sampled in March 2008 to evaluate the spatial variability of SOC and nitrogen (N) contents in relation to the spacing between trees. In September 2009, soils were sampled to evaluate the soil C stocks in the avenues (inter rows) and frond piles, and to compare the total C stocks with natural forest and pasture system. Soil C contents were 22–38% higher in the area nearest the oil palm base (0.6 m) than the average across the inter row (0–4.5 m from the tree), indicating that the increment in soil organic matter (SOM) must have been largely derived from root material. The soil C stocks under palm frond piles were 9–26% higher than in the inter rows, due to inputs of SOM by pruned palm fronds. The soil carbon stocks in oil palm areas, after adjustments for differences in bulk density and clay content across treatments, were 35–46% lower than pasture soil C stocks, but were 0–18% higher than the native forest soil C content. The results found here may be used to improve the life cycle assessment of biodiesel derived from palm oil.     

Environmental policy at a critical junction in the Brazilian Amazon

Wholesale conversion of natural Amazonian ecosystems has been encouraged by Brazil’s extreme antienvironmental government, and historical forest loss explains municipal-scale voting prevalence. Embracing a new administration would strengthen local-to-regional governance, suppress illegal land grabbing, deforestation, logging, and gold mining, thereby protecting the world’s most species-rich forest domain and ensuring global sustainability.     

Microzooplankton as an indicator of environmental quality at an industrial complex in the Brazilian Amazon

The large volume of water in the Pará River, together with governmental incentives, has attracted many industries to the city of Barcarena, Brazil. This industrial activity has the potential to cause changes to aquatic environments. Zooplankton species are considered good indicators of environmental changes. We assessed the association between changes in community composition and proximity to an industrial-port complex, and identified potential bioindicator species in these environments. Five quarterly sampling points were selected along the Pará River (P1–P5) in 2012. The zooplankton community in this region is composed of 64 species. The highest total densities were recorded in February and November, which are both during the rainy season. Zooplankton density was greatest at P3, which was near an industrial-port complex, suggesting that industrial activity affected zooplankton density. An IndVal test showed the rotifer Filinia opoliensis (r = 0.86, p = 0.02) to be a possible bioindicator of environmental quality in the study area. This paper contributes to the discussion of the impacts of installing industrial plants and large ports in the Amazon.     

Deforestation and land use in the Brazilian Amazon

Deforestation in the Brazilian Amazon was less than 1% before 1975. Between 1975 and 1987 the rate increased exponentially. By 1985, world opinion and attention to the destruction of the richest biome on earth led to elimination of some of the major incentives that had fueled deforestation. Favorable credit policies for cattle ranchers, rather than population growth, explains the process of deforestation in the Brazilian Amazon. The paper suggests other actions that may be taken to reduce deforestation, and examines the rapid growth rates of secondary successional species in a colonization area.     

Haplotype diversity of 17 Y-str loci in an admixed population from the Brazilian Amazon

The allelic and haplotype frequencies of 17 Y-STR loci most commonly used in forensic testing were estimated in a sample of 138 unrelated healthy males from Macapá, in the northern Amazon region of Brazil. The average gene diversity was 0.6554 ± 0.3315. 134 haplotypes of the 17 loci were observed, 130 of them unique and four present in two individuals each. The haplotype diversity index was 0.9996 + 0.0009, with the most frequent haplogroups being R1b (52.2%), E1b1b (11.6%), J2 (10.1%) and Q (7.2%). Most haplogroups of this population belonged to European male lineages (89.2%), followed by Amerindian (7.2%) and African (3.6%) lineages.     

Spatial distribution of triatomines in domiciles of an urban area of the Brazilian Southeast Region

Reports of triatomine infestation in urban areas have increased. We analysed the spatial distribution of infestation by triatomines in the urban area of Diamantina, in the state of Minas Gerais, Brazil. Triatomines were obtained by community-based entomological surveillance. Spatial patterns of infestation were analysed by Ripley’s K function and Kernel density estimator. Normalised difference vegetation index (NDVI) and land cover derived from satellite imagery were compared between infested and uninfested areas. A total of 140 adults of four species were captured (100 Triatoma vitticeps, 25Panstrongylus geniculatus, 8 Panstrongylus megistus, and 7 Triatoma arthurneivai specimens). In total, 87.9% were captured within domiciles. Infection by trypanosomes was observed in 19.6% of 107 examined insects. The spatial distributions ofT. vitticeps, P. geniculatus, T. arthurneivai, and trypanosome-positive triatomines were clustered, occurring mainly in peripheral areas. NDVI values were statistically higher in areas infested by T. vitticeps and P. geniculatus. Buildings infested by these species were located closer to open fields, whereas infestations of P. megistus andT. arthurneivai were closer to bare soil. Human occupation and modification of natural areas may be involved in triatomine invasion, exposing the population to these vectors.     

Effects of DOM photochemistry on bacterial metabolism and CO2 evasion during falling water in a humic and a whitewater river in the Brazilian Amazon

In the Amazon river system, the source of the large quantity of CO₂ evading from river surfaces remains unidentified. Photochemical transformation of dissolved organic matter (DOM) into dissolved inorganic carbon (DIC) and low molecular weight organic acids (LMWOAs) is a promising candidate. Few studies in the Amazon river system, and river systems in general, have attempted to quantify the contribution of these specific photoproducts to CO₂ evasion. We conducted photochemical degradation and ¹⁴C addition experiments to measure the rate of production and the impact on bacterial metabolism, respectively, in the black water Rio Negro and in the white water Rio Solimões during low water. We found statistically significant production of both photoproducts in the Rio Negro and none in Rio Solimões. We also found that two photochemically produced LMWOAs??acetic and formic acid??may play a significant role in bacterial metabolism in both rivers. Based on our experimental results, we estimate that photochemically produced CO₂, acetic acid and formic acid alone contribute to only 0.5% of the CO₂ evading from the Rio Negro. Due to our experimental set-up, analytical methods and time of sampling, we caution that our estimate is very conservative. More extensive research is needed before drawing conclusions on the contribution of photochemistry to CO₂ evasion from river surfaces of the Amazon basin.     

Predictive Modelling of Contagious Deforestation in the Brazilian Amazon

Tropical forests are diminishing in extent due primarily to the rapid expansion of agriculture, but the future magnitude and geographical distribution of future tropical deforestation is uncertain. Here, we introduce a dynamic and spatially-explicit model of deforestation that predicts the potential magnitude and spatial pattern of Amazon deforestation. Our model differs from previous models in three ways: (1) it is probabilistic and quantifies uncertainty around predictions and parameters; (2) the overall deforestation rate emerges “bottom up”, as the sum of local-scale deforestation driven by local processes; and (3) deforestation is contagious, such that local deforestation rate increases through time if adjacent locations are deforested. For the scenarios evaluated–pre- and post-PPCDAM (“Plano de Ação para Proteção e Controle do Desmatamento na Amazônia”)–the parameter estimates confirmed that forests near roads and already deforested areas are significantly more likely to be deforested in the near future and less likely in protected areas. Validation tests showed that our model correctly predicted the magnitude and spatial pattern of deforestation that accumulates over time, but that there is very high uncertainty surrounding the exact sequence in which pixels are deforested. The model predicts that under pre-PPCDAM (assuming no change in parameter values due to, for example, changes in government policy), annual deforestation rates would halve between 2050 compared to 2002, although this partly reflects reliance on a static map of the road network. Consistent with other models, under the pre-PPCDAM scenario, states in the south and east of the Brazilian Amazon have a high predicted probability of losing nearly all forest outside of protected areas by 2050. This pattern is less strong in the post-PPCDAM scenario. Contagious spread along roads and through areas lacking formal protection could allow deforestation to reach the core, which is currently experiencing low deforestation rates due to its isolation.     

Diversity of the KIR gene cluster in an urban Brazilian population

The activity of natural killer cells depends on the balance between activating and inhibitory signals coming from their receptors. Among these are the killer cell immunoglobulin-like receptors (KIR) that recognize specific HLA class I allotypes. Here we characterized KIR genetic diversity and their HLA ligands in the population of Curitiba, Paraná State (n = 164), and compared it with other worldwide populations. The distribution of 2DL4 alleles was also analyzed. The Curitiba population did not differ significantly from European and Euro-descendant populations, but as an admixed population showed higher genetic diversity. We found 27 KIR profiles, many of them uncommon in European populations, in agreement with the elevated historically recent gene flow in the study population. The frequencies of KIR genes and their respective HLA ligands were distributed independently and none of the analyzed individuals lacked functional KIR–HLA ligand combinations. KIR gene frequencies of 33 worldwide populations were consistent with geographic and ethnic distribution, in agreement with demography being the major factor shaping the observed gene content diversity of the KIR locus.     

The net carbon flux due to deforestation and forest re-growth in the Brazilian Amazon: analysis using a process-based model

We developed a process‐based model of forest growth, carbon cycling and land‐cover dynamics named CARLUC (for CARbon and Land‐Use Change) to estimate the size of terrestrial carbon pools in terra firme (nonflooded) forests across the Brazilian Legal Amazon and the net flux of carbon resulting from forest disturbance and forest recovery from disturbance. Our goal in building the model was to construct a relatively simple ecosystem model that would respond to soil and climatic heterogeneity that allows us to study the impact of Amazonian deforestation, selective logging and accidental fire on the global carbon cycle. This paper focuses on the net flux caused by deforestation and forest re‐growth over the period from 1970 to 1998. We calculate that the net flux to the atmosphere during this period reached a maximum of ～0.35 PgC yr^?1 (1 PgC= 1 × 10¹⁵ gC) in 1990, with a cumulative release of ～7 PgC from 1970 to 1998. The net flux is higher than predicted by an earlier study ( Houghton et al., 2000 ) by a total of 1 PgC over the period 1989–1998 mainly because CARLUC predicts relatively high mature forest carbon storage compared with the datasets used in the earlier study. Incorporating the dynamics of litter and soil carbon pools into the model increases the cumulative net flux by～1 PgC from 1970 to 1998, while different assumptions about land‐cover dynamics only caused small changes. The uncertainty of the net flux, calculated with a Monte‐Carlo approach, is roughly 35% of the mean value (1 SD).     

Structure of hydrophilic vegetation of a small river in an urban environment

The hydrophilic vegetation of the small Korovka River has been characterized in the urban and suburban zones of the city of Rybinsk (Yaroslavl oblast). The structure and state of the vegetation within the urban territory depends mainly on the anthropogenic load and hydrological factors. The main phytocoenoses of urban and suburban zones are hydrophilic and helophilic complexes, respectively. The level of overgrowth of these zones varies within the range of 30–70% and 5–20%, respectively. The following overgrowth patterns dominate in the urban zone: mosaic thicket, border, and underwater meadow. In the case of the suburban zone, the border and thicket patterns dominate.     

Edge effect benefits galling insects in the Brazilian Amazon

We investigated the influence of edge effects on communities of galling insects in the Brazilian Amazon. For this, were performed data analyses comparing the galling richness between disturbed and undisturbed areas, and subsequently evaluated the richness of galling at different distances from the forest edge. We registered 194 galling insect morphotypes in 116 host plant species. Galling insect richness was more pronounced in disturbed areas and closer to the forest edge, both to community in general as to specific host plant taxa. These results indicate positive responses of galling insect richness to edge effects in forest environments. Edge effect could influence the galling distribution in modified habitats because increases the stress conditions of the plants and decreases the attack pressure of natural enemies.     

Assessing the impacts of ecological governance on carbon storage in an urban coal mining subsidence area

Carbon storage, which is considered one of the important service functions of ecosystems, plays an irreplaceable role in maintaining the regional carbon balance and regulating the climate. Regional carbon storage is closely related to regional land use and land cover (LULC). With the development and expansion of coal resource-based cities, the construction areas of cities have started to overlap with underground coal resources. Coal mining leads to regional LULC changes, such as large-scale surface subsidence and subsidence waterlogging, and LULC has changed and consequently affected carbon storage in urban coal mining subsidence areas. This study analyses the change trend of carbon storage and clarifies the effect of ecological governance being implemented in the urban coal mining subsidence area. First, the LULC change map of the ecological governance scenario was obtained via remote sensing technology. Then, the natural evolution scenario from 2000 to 2021 was simulated using the hybrid cellular automata and Markov chain, also named the CA–Markov model. Finally, combined with the subsidence waterlogging in the urban subsidence area, the InVEST model was used to analyse the spatial–temporal variation characteristics of carbon storage. The analysis results showed that LULC and carbon storage in small-scale urban coal mining subsidence areas changed dramatically between 2000 and 2021 due to coal mining and ecological governance. The subsidence waterlogging area increased by 1033.83 ha, resulting in total carbon storage decreasing by 37,560.21 t. Subsidence waterlogging is the key influencing factor in the decrease in carbon storage. The forest area increased by 1270.83 ha, resulting in a total carbon storage increase of 216,531.04 t. Forest is the crucial increasing factor in carbon storage. The changes in carbon storage in the urban coal mining subsidence area can be classified as follows: obvious improvement area, basically unchanged area, and significantly degraded area. As opposed to the natural evolution scenario, the ecological governance scenario increased the coverage of the “obvious improvement area” by 818.46 ha in the urban coal mining subsidence area. Overall, this study illustrates that ecological governance can effectively improve carbon sequestration and is conducive to the healthy development of coal resource-based cities.     

Modelling the role of urban forest in the regulation of carbon balance in an industrial area of India

The increase in greenhouse gases, especially carbon dioxide, in the atmosphere contributes to climate change. People and policy makers are becoming more interested in the role of urban trees in regulating the global carbon cycle. Carbon dioxide emissions from anthropogenic sources are mainly caused by the burning of fossil fuels, which are major contributors to the increase in greenhouse gases in the atmosphere. Therefore, a better understanding of the carbon sequestration process by urban forests and its exchange between air and soil is the first step to offsetting the impacts of climate change in urban areas.Here, a dynamic model was constructed including the carbon stock of forest, litter carbon and soil organic carbon pool. The study emphasized the relationship between the three carbon pools. The monthly dynamics of the pools were studied. A sensitivity analysis was performed followed by calibration and validation. The results showed that the mean growth rate of forest biomass was the most sensitive factor, followed by the decomposition rate and the uptake rate of organic carbon by detritivores.If the biomass of the existing forest is maintained sustainably, more carbon dioxide could be sequestered. In addition, the model showed that afforestation in the Asansol-Durgapur Planning Area would increase the carbon stocks of the forest and to some extent offset the problem of carbon dioxide release from the nearby coal mines and other factories. In the near future, the model will benefit forest managers in carrying out urban management in the Earth's tropical belt.