Southeastern Amazonia Research Articles

Modelling the Effects of Historical and Future Land Cover Changes on the Hydrology of an Amazonian Basin

Land cover changes (LCC) affect the water balance (WB), changing surface runoff (SurfQ), evapotranspiration (ET), groundwater (GW) regimes, and streamflow (Q). The Tapajós Basin (southeastern Amazon) has experienced LCC over the last 40 years, with increasing LCC rates projected for the near future. Several studies have addressed the effects of climate changes on the region’s hydrology, but few have explored the effects of LCC on its hydrological regime. In this study, the Soil and Water Assessment Tool (SWAT) was applied to model the LCC effects on the hydrology of the Upper Crepori River Basin (medium Tapajós Basin), using historical and projected LCC based on conservation policies (GOV_2050) and on the “Business as Usual” trend (BAU_2050). LCC that occurred from 1973 to 2012, increased Q by 2.5%, without noticeably altering the average annual WB. The future GOV_2050 and BAU_2050 scenarios increased SurfQ by 238.87% and 300.90%, and Q by 2.53% and 2.97%, respectively, and reduced GW by 4.00% and 5.21%, and ET by 2.07% and 2.43%, respectively. Results suggest that the increase in deforestation will intensify floods and low-flow events, and that the conservation policies considered in the GOV_2050 scenario may still compromise the region’s hydrology at a comparable level to that of the BAU_2050.

Comments on the genus Diplura C. L. Koch, 1850, with description of two new species (Araneae, Mygalomorphae, Dipluridae).

Two new species of Diplura C. L. Koch 1850 are described from Brazil: Diplura mapinguari sp. n., from the state of Rondônia in southeastern Amazonia, northern Brazil, and Diplura rodrigoi sp. n., known from southeastern and central west regions of Brazil. Diplura rodrigoi sp. n. is morphologically similar to D. lineata (Lucas, 1857), D. sanguinea (F. O. Pickard-Cambridge, 1896), and D. mapinguari sp. n. Comments on diagnostic characters of Diplura are included. The synonymy of D. maculata (Mello-Leitão, 1927) with D. catharinensis (Mello-Leitão, 1923) is corroborated. A classification of color pattern of the dorsum of the abdomen is given.

Morphology and morphometry of upland lakes over lateritic crust, Serra dos Carajás, southeastern Amazon region.

High-resolution satellite images, digital elevation models, bathymetric and sedimentological surveys coupled with statistical analysis were used to understand the physical environment and discuss their influence on water quality of the five upland lakes of Serra Sul dos Carajás, southeast Amazonia. The lakes have mid-altitude ranges (elevation), very small (catchment) and shallow to very shallow (central basins). Based on the length, area and volume, Violão and TI (Três Irmãs)-3 lakes may present large vertical movements of the water due to wind action and weakly stratified waters. Trophic conditions based on depth and shore development (Ld) parameters must be used with caution, since Amendoim Lake is relatively deep, but it is oligotrophic to ultra-oligotrophic. Ld values suggest that the lakes are circular to subcircular and are likely formed by solution process, as also suggested by volume development. TI-2 Lake is only presenting convex central basin and has highest dynamic ratio (DR), thus it may have high sedimentation and erosion rates. Based on the relationship between studied parameters, morphometric index and DR likely influence temperature and dissolved oxygen of waters of TI-2 Lake due to its depth profile and wind-induced surface mixing. Nevertheless, water quality parameters are controlled by catchment characteristics of the lakes.

Deforestation and stream warming affect body size of Amazonian fishes.

Declining body size has been suggested to be a universal response of organisms to rising temperatures, manifesting at all levels of organization and in a broad range of taxa. However, no study to date evaluated whether deforestation-driven warming could trigger a similar response. We studied changes in fish body size, from individuals to assemblages, in streams in Southeastern Amazonia. We first conducted sampling surveys to validate the assumption that deforestation promoted stream warming, and to test the hypothesis that warmer deforested streams had reduced fish body sizes relative to cooler forest streams. As predicted, deforested streams were up to 6 °C warmer and had fish 36% smaller than forest streams on average. This body size reduction could be largely explained by the responses of the four most common species, which were 43–55% smaller in deforested streams. We then conducted a laboratory experiment to test the hypothesis that stream warming as measured in the field was sufficient to cause a growth reduction in the dominant fish species in the region. Fish reared at forest stream temperatures gained mass, whereas those reared at deforested stream temperatures lost mass. Our results suggest that deforestation-driven stream warming is likely to be a relevant factor promoting observed body size reductions, although other changes in stream conditions, like reductions in organic matter inputs, can also be important. A broad scale reduction in fish body size due to warming may be occurring in streams throughout the Amazonian Arc of Deforestation, with potential implications for the conservation of Amazonian fish biodiversity and food supply for people around the Basin.

New records of the rare little rufous mouse opossum, Marmosa lepida (Thomas,1888) (Mammalia, Didelphidae) in southeastern Amazonia, Brazil

New records of the rare little rufous mouse opossum, Marmosa lepida (Thomas,1888) (Mammalia, Didelphidae) in southeastern Amazonia, Brazil

Pleroma carajasense (Melastomataceae), a new species endemic to ironstone outcrops in the Brazilian Amazon

A new species of Pleroma from Serra dos Carajás, Pará state, Brazil, is described. Pleroma carajasense occurs in southeastern Amazonia, northern Brazil, in canga vegetation, on ironstone outcrops. It is morphologically related to Tibouchina caatingae, because both are shrubs with elliptic to oval leaves, conspicuous petioles (3–17 mm and 10–15 mm, respectively), a pair of elliptic bracteoles, and purple petals, anthers (both cycles) and style. Pleroma carajasense differs from T. caatingae by its chartaceous leaves (versus coriaceous in T. caatingae), with an obtuse to cuneate base (vs. obtuse to subcordate), hypanthium 4–7 × 1.2–4 mm (vs. 10–15 × 3–5 mm). According to IUCN criteria, this species should be considered endangered (EN). A morphological description, illustrations, photos in the field, scanning electronic micrographs of the leaf indumentum and seeds, information on conservation status and distribution are presented.

Aspects on the ecology of phlebotomine sand flies and natural infection by Leishmania hertigi in the Southeastern Amazon Basin of Brazil

The medical and veterinary importance of sand flies (Diptera: Psychodidae) follow as a result of some species ability to transmit the zoonotic protozoa of the genus Leishmania. Of all municipalities in the state of Mato Grosso, Sinop ranks first in reported cases of American Cutaneous Leishmaniasis (ACL). Sinop urban zone encompasses three permanent forest preservation areas (APPs) that provide refuge for insects and other vertebrate hosts. We assessed ecological parameters and investigated the natural infection by Leishmania spp. of the phlebotomine fauna from four ecotypes with different levels of urbanization in the urban area of Sinop. A total of 62,745 sand flies were collected, of which 52.34% female. Out of 37 species in this study, nine were found to be constant. Sand flies frequency and diversity were highest in APPs (96.85%; 33 species). Lutzomyia dasypodogeton was the most frequent species and exhibited the greatest abundance (SISA=0.977). The neighborhoods around APPs and completely urbanized neighborhoods presented noteworthy ecological similarity. Moreover, eight vector sand fly species with medicalwere identified, and one L. antunesi sample pool was found to be naturally infected with Le. hertigi. We observed a high frequency and diversity of sand flies, including some species that are known to be major vectors of ACL. Further studies are needed on the natural rates of infection in humans, domestic animals, and sylvatic hosts to better comprehend the leishmaniases dynamics.

Technical note: A hydrological routing scheme for the Ecosystem Demography model (ED2+R) tested in the Tapajós River basin in the Brazilian Amazon

Abstract. Land surface models are excellent tools for studying how climate change and land use affect surface hydrology. However, in order to assess the impacts of Earth processes on river flows, simulated changes in runoff need to be routed through the landscape. In this technical note, we describe the integration of the Ecosystem Demography (ED2) model with a hydrological routing scheme. The purpose of the study was to create a tool capable of incorporating to hydrological predictions the terrestrial ecosystem responses to climate, carbon dioxide, and land-use change, as simulated with terrestrial biosphere models. The resulting ED2+R model calculates the lateral routing of surface and subsurface runoff resulting from the terrestrial biosphere models' vertical water balance in order to determine spatiotemporal patterns of river flows within the simulated region. We evaluated the ED2+R model in the Tapajós, a 476 674 km2 river basin in the southeastern Amazon, Brazil. The results showed that the integration of ED2 with the lateral routing scheme results in an adequate representation (Nash–Sutcliffe efficiency up to 0.76, Kling–Gupta efficiency up to 0.86, Pearson's R up to 0.88, and volume ratio up to 1.06) of daily to decadal river flow dynamics in the Tapajós. These results are a consistent step forward with respect to the no river representation common among terrestrial biosphere models, such as the initial version of ED2.

Metastability for discontinuous dynamical systems under L\xe9vy noise: Case study on Amazonian Vegetation

For the tipping elements in the Earth’s climate system, the most important issue to address is how stable is the desirable state against random perturbations. Extreme biotic and climatic events pose severe hazards to tropical rainforests. Their local effects are extremely stochastic and difficult to measure. Moreover, the direction and intensity of the response of forest trees to such perturbations are unknown, especially given the lack of efficient dynamical vegetation models to evaluate forest tree cover changes over time. In this study, we consider randomness in the mathematical modelling of forest trees by incorporating uncertainty through a stochastic differential equation. According to field-based evidence, the interactions between fires and droughts are a more direct mechanism that may describe sudden forest degradation in the south-eastern Amazon. In modeling the Amazonian vegetation system, we include symmetric α-stable Lévy perturbations. We report results of stability analysis of the metastable fertile forest state. We conclude that even a very slight threat to the forest state stability represents L´evy noise with large jumps of low intensity, that can be interpreted as a fire occurring in a non-drought year. During years of severe drought, high-intensity fires significantly accelerate the transition between a forest and savanna state.

Results confirm a relatively dry setting during the last glacial (MIS 3 and LGM) in Carajás, Amazonia: A comment on Guimarães et al.

Recent pollen rain data from lake Amendoim in Carajas (southeastern Amazonia) revealed a dominant forest formation spectrum where, locally, montane savannas occupy a larger proportion of the lake’s...

Pollen morphology of the Poaceae: implications of the palynological and paleoecological records of the southeastern Amazon in Brazil

ABSTRACTA detailed assessment of Poaceae pollen morphology was performed using light and scanning electron microscopy (LM and SEM, respectively), digital image processing and multivariate data analysis of species from the montane savanna (canga vegetation) of the Serra dos Carajas region in the southeastern Amazon to discriminate the lower taxonomic levels and, accordingly, the habitat types of Poaceae. Poaceae pollen are generally stenopalynous monoporate grains with annulate and operculate pores, and distinguishing species by ornamentation using LM is impossible. Under SEM, Poaceae have mainly areolate microechinate/granulose ornamentation, except for Eragrostis maypurensis (rugulate-microechinate), Andropogon bicornis, Trichanthecium parvifolium and T. polycomum (rugulate granulose), and Rhytachne gonzalezii (microechinate). Digital image processing of ornamentation under SEM coupled with multivariate data analysis allowed for differentiation between the E. maypurensis, R. gonzalezii, A. capillaris, Otachyrium versicolor, Paspalum carinatum and T. polycomum. Distinguishing species of the wet savanna, such as Isachne polygonoides, R. gonzalezii, O. versicolor, P. virgatum, and T. polycomum, from species of the dry savanna can improve paleoecological and paleoclimatic interpretations.

Forest-savanna boundary shift on the plateau of Serra Sul dos Carajás (southeastern Amazonia) since the mid-Holocene; driving forces and limiting factors

The vegetation history of the savanna on the plateau of Serra Sul dos Carajás (PSSC) is well studied by three palynological records. Nonetheless there is no record from the forests around this plateau so that the long term forest-savanna boundary shift can be investigated. In this study, a sediment core taken from the forests on the slopes of the plateau is studied using a multi-proxy analysis. The palynological result is compared with the records from adjacent savanna. This study reveals that well-established forests have been present around the plateau during the last 6600 cal yr BP. Since the mid-Holocene owing to a change to favorable climatic conditions, forests started to move toward the savanna and after 3400–4000 years reached their modern borders in the savanna region. Because during this long period forest borders moved horizontally a relatively short distance (ca. 250 m), we concluded that there might be limiting factors that delayed forest expansion. Among different possible factors, fire and human may play an important role. However, the evidence suggests that the slow process of soil formation to produce a soil layer with sufficient depth is the main limiting factor that delayed the forest expansion. According to the previous hydroclimatic and palaeo-ecological studies, the southward displacement of Inter Tropical Convergence Zone (ITCZ) is more likely the trigger of forest expansion in the area since the mid-Holocene.

Environmental and vegetation changes in southeastern Amazonia during the late Pleistocene and Holocene

New insights about climate conditions and their effect on vegetation and lakes of southeastern Amazonia were achieved over the last 50 cal ka using recent data obtained from a filled lake located in the Serra Sul de Carajás. Our analysis was done in a sediment core (R2) comprising of faciological, palynological, isotopic and radio carbon measurement supported by Bayesian age-depth modeling, as well species distribution modeling. Wet and cool climate conditions are proposed for the mid-Pleniglacial, which is favorable to intense weathering of the lake's catchment area and the expansion of high altitude taxa (cool-adapted) into forest formations during this period. From the late Pleniglacial to the Last Glacial Maximum, a change from relatively wet to dry climate possibly converted the studied lake from oxidizing to reducing conditions, which leads to the formation of diagenetic siderites at the end of this time interval. Warming during the Pleistocene to Holocene transition caused the disappearance of cool-adapted taxa in the study site. Concomitantly, increasing precipitation allowed the expansion of forest and high lake levels. A drier early-mid Holocene produced extensive open vegetation and desiccated lakes. Current climate and environmental conditions were likely attained in the region from the mid to late Holocene.

Ecological relations are affective relations: the Xinguan Kaiabi and the proximity with the Teles Pires River (southeastern Amazonia, Brazil)

ABSTRACTThis article reflects mainly on the attachment relationships construed by the Kaiabi indigenous people from Xingu Park (southeastern Amazonia, Brazil) with the particular environment of the Teles Pires River valley, a region in which they used to dwell in the past. Even 50 years after they were forced to relocate to a new environment – Xingu Park – the Kaiabi have found creative and powerful strategies – that go beyond material subsistence – to renew and preserve their affective connection of practical engagement with their old sacred places, despite being physically distant to them. Based on interviews with the Elders, and the experience of participating in the daily life movements of the young Kaiabi, and observing the importance of the paths traced by their ancestors, I propose to analyze how new generations of Kaiabi give meaning to their lives by using elements that connect mind and body to affirm their ethnic identity in close association with the environment of the Teles Pires River valley.

Basin morphology, sedimentology and seismic stratigraphy of an upland lake from Serra dos Carajás, southeastern Amazon, Brazil

To understand the sedimentary processes in a lake environment, it is essential to investigate the morphological, sedimentalogical and limnological features of the basin. The present study was developed at Violão Lake, Serra Sul de Carajás. The methodological approach comprises the collection of bathymetric and sedimentary data, and shallow seismic profiles. Lake Violão has a NE-SW elongated guitar-shaped form and ~0.3 km2 of surface area, with a perimeter of ~2.7 km. The lake presents washing basin morphology and it is marked by a steep margin carved in duricrust outcrops, while the bottom is flat and constituted mainly by muddy sediments. The water column is stratified only during the dry season and it is mixed in the rainy season. Three seismic stratigraphic successions were identified in the lake resting on prominent basal reflector (bedrock), which reaches a maximum depth of ~15 m. Small lobate masses are deposited in the bottom of the lake from underflows, while the central part of the lake is characterized by drape deposition, suggesting that organic-mud sedimentation is associated to pelagic deposition from dilute interflows or overflows. Therefore, the sedimentary processes are strongly regulated by basin morphology, drainage water inflow and thermal stratification of the water column.

Avian malaria, ecological host traits and mosquito abundance in southeastern Amazonia.

Avian malaria is a vector transmitted disease caused by Plasmodium and recent studies suggest that variation in its prevalence across avian hosts is correlated with a variety of ecological traits. Here we examine the relationship between prevalence and diversity of Plasmodium lineages in southeastern Amazonia and: (1) host ecological traits (nest location, nest type, flocking behaviour and diet); (2) density and diversity of avian hosts; (3) abundance and diversity of mosquitoes; and (4) season. We used molecular methods to detect Plasmodium in blood samples from 675 individual birds of 120 species. Based on cytochrome b sequences, we recovered 89 lineages of Plasmodium from 136 infected individuals sampled across seven localities. Plasmodium prevalence was homogeneous over time (dry season and flooding season) and space, but heterogeneous among 51 avian host species. Variation in prevalence among bird species was not explained by avian ecological traits, density of avian hosts, or mosquito abundance. However, Plasmodium lineage diversity was positively correlated with mosquito abundance. Interestingly, our results suggest that avian host traits are less important determinants of Plasmodium prevalence and diversity in southeastern Amazonia than in other regions in which they have been investigated.

Ichnologic evidence of a Cambrian age in the southern Amazon Craton: Implications for the onset of the Western Gondwana history

Colonization of the infaunal ecospace by burrowing bilaterians is one of the most important behavioral innovations during the Ediacaran-Cambrian transition. The establishment of vertical burrows by suspension feeders in high-energy nearshore settings during Cambrian Age 2 is reflected by the appearance of the Skolithos Ichnofacies. For the first time, unquestionable vertical burrows typical of the Skolithos Ichnofacies, such as Skolithos linearis, Diplocraterion parallelum and Arenicolites isp., are recorded from nearshore siliciclastic deposits of the Raizama Formation, southeastern Amazon Craton, Brazil. Integration of ichnologic and sedimentologic datasets suggests that these trace fossils record colonization of high-energy and well-oxygenated nearshore sandy environments. Chronostratigraphically, the presence of these vertical burrows indicates an age not older than early Cambrian for the Raizama Formation, which traditionally has been regarded as Ediacaran. Therefore, the Raizama ichnofauna illustrates the advent of modern Phanerozoic ecology marked by the Agronomic Revolution. The discovery of the Skolithos Ichnofacies in these shallow-marine strata suggests possible connections between some central Western Gondwana basins.

Run, hide, or fight: anti-predation strategies in endangered red-nosed cuxiú (Chiropotes albinasus, Pitheciidae) in southeastern Amazonia.

Although primate predation is rarely observed, a series of primate anti-predation strategies have been described. Energetic costs of such strategies can vary from high-cost mobbing, via less costly alarm calling, to low-cost furtive concealment. Here we report the anti-predation strategies of red-nosed cuxiú, Chiropotes albinasus, based on direct observations from four study sites in southeastern Brazilian Amazonia. Over a collective period of 1255 fieldwork hours, we observed nine direct interactions between raptors (all potential predators) and red-nosed cuxiús. Of these, one (11%) resulted in predation. Raptors involved were: Harpia harpyja (four events), Leucopternis sp. (two events), Spizaëtus tyrannus (one event), and unidentified large raptors (two events). Predation attempts occurred in flooded-forest and terra firme rainforest, were directed at both adult and non-adult cuxiús, and involved both adult and juvenile raptors. Anti-predation strategies adopted by the cuxiús included: (1) group defence and mobbing behaviour (two occasions), (2) dropping into dense sub-canopy (seven occasions), (3) alarm calling (eight occasions), and (4) fleeing to, and hiding in, dense vegetation (eight occasions). During each encounter at least two of these behaviours were recorded. These are the first published records of predation, predation attempts, and anti-predator behaviour involving red-nosed cuxiú.

Modern pollen rain as a background for palaeoenvironmental studies in the Serra dos Carajás, southeastern Amazonia

Several alternative interpretations of the pollen records of lake sediments in the Amazonia may arise due to a lack of understanding of the modern environments, mainly related to pollen–vegetation relationship. Therefore, in this work, we studied the modern pollen rain in sediments of the Amendoim Lake, plateaus of the Serra Sul dos Carajás, southeastern Amazonia. This study indicates the predominance of pollen grains from forest formation (ombrophilous forests and capão florestal) over montane savanna in the lake sediments, despite the fact that montane savanna occupies ~90% of the drainage basin. Additionally, these sediments reflect stronger signal of pollen from ombrophilous forests that occur in the slopes of the plateau. Important components of montane savanna such as Vellozia and Cereus were not observed in the modern pollen rain, which may be related to their shorter flowering periods restricted to the beginning of wetter conditions. The absence of Sacoglottis, Trichilia, Clusia, Emmotum, Guapira and Simarouba in the pollen rain is likely associated with different pollination strategy. The occurrence of windblown pollen of Alchornea, Pseudolmedia, Ilex and Cecropia, which are found from low to highlands of the Carajás region, reinforces a regional vegetation signal in sediments. Several plants from the studied site have been improperly described, according to taxonomy and ecology. For example, the current occurrence of Ilex and Styrax in the study site clearly suggests that they cannot be used as indicators of colder palaeoclimate conditions, as previously described. In addition, Poaceae can be found in drier to wetter substrate conditions, and abundance of their pollen grains in lakes can significantly vary according to relief morphology and cannot indicate palaeovegetation openness. Therefore, this work is a good background for further palaeobotany studies for this region.

Response of South American Terrestrial Ecosystems to Future Patterns of Sea Surface Temperature

Global warming in the first half of the 21st century is likely to have profound influences on South American vegetation and climate. Although coupled atmosphere-biosphere models have been widely used to forecast future vegetation patterns under various scenarios of global warming, they have not been used to assess the potentially critical role of variations in sea surface temperature (SST) in modifying the climate-vegetation interactions. Here, we use monthly output of a 100-year coupled model run to investigate the relationship between SST, precipitation, and productivity of vegetation. Specifically, we assess statistical correlations between SST variability and vegetation in six different South America regions: Northern South America, Western Amazonia, Eastern Amazonia, Northeast Brazil, Central Brazil, and Patagonia. Our model robustly simulates changes in mean precipitation, net primary production (NPP), upper canopy leaf area index (LAI), and lower canopy LAI under warming and nonwarming scenarios. Most significantly, we demonstrate that spatial-temporal variability in SST exerts a strong influence over the vegetation dynamics in all six South American regions.