Amazonian Savanna Research Articles

Comolia paraensis (Melastomataceae), a striking new species of Marcetieae endemic to Pará, Brazil

During the preparation of the taxonomic review of Comolia, some taxonomic novelties were found. Here we describe Comolia paraensis, a new species endemic to the Brazilian state of Pará, preliminary categorized as Endangered. This species occurs in the campinas around Oriximiná and in the stony Amazonian savannas of Monte Alegre and Óbidos. Comolia paraensis is morphologically similar to C. kuhlmannii and C. veronicifolia, two taxonomic entities that here were considered distinct from C. villosa. Comolia paraensis is illustrated, compared with similar species, and notes on its geographic distribution and preliminary conservation status are provided. We also discuss the succulence found in the branches of the population from Monte Alegre, something unprecedented within Marcetieae, but commonly reported in Pyramieae and Sonerileae.

Mosquitoes (Diptera: Culicidae) of the Amazonian savannas of French Guiana with a description of two new species.

Amazonian savannas are among the most noteworthy landscape components of the coastal plain of French Guiana. Although they cover only 0.22% of the territory, they bring together a large part of the animal and plant diversity of this overseas region of France. This article outlines the results of the first study dedicated to mosquitoes (Diptera: Culicidae) of Amazonian savannas. Samplings were conducted in eight independent savannas evenly distributed along a transect of 170 km on the coastal plain of French Guiana. A total of 50 mosquito species were recorded, which is about 20% of the culicid fauna currently known in French Guiana. Among them, Culex (Melanoconion) organaboensis sp. nov. and Cx. (Mel.) zabanicus sp. nov. are newly described based on both morphological features of the male genitalia and a DNA barcode obtained from type specimens. Diagnostic characters to assist their identification are provided and their placement within the infrasubgeneric classification of the subgenus Melanoconion is discussed.

Bioactivity of aqueous extracts of annonaceous from the amazon savannah of Roraima on the cowpea aphid

Aphis craccivora Koch (Hemiptera: Aphididae), known as the cowpea aphid, is a polyphagous pest that causes severe damage throughout the phenological cycle of several economically important crops. For the control of this hemiptera, as for most agricultural pests, the chemical method has been the most used. Considering the Integrated Pest Management - IPM, the use of plant extracts is an option that has been widely considered. Thus, this study aimed to evaluate the bioactivity of aqueous extracts of Annona glabra, A. hypoglauca, A. montana and A. squamosa leaves, obtained in the Amazonian Savanna of Roraima, Brazil, on A. craccivora under laboratory conditions. Regarding the biological aspects on the cowpea aphid, the toxicity and repellency were evaluated with and without chance of choice. It was verified that the aqueous extracts of the four species of the genus Annona cause mortality in both nymphal and adult stages of A. craccivora, besides presenting repellent effect for this aphid. Because the aqueous extracts of leaves of the studied species present promising effects against A. craccivora, additional field studies of bioactivity of these Annona species on the black aphid, as well as their activity on beneficial and non-target organisms are suggested.

Functional leaf traits in congeneric species of tree communities in central Amazon

The Amazon is a Neotropical region that features various types of phytophysiognomies subject to multiple environmental filters. The Amazonian Savanna and Ombrophilous Forest areas support complex ecosystem functions and are sensitive to biotic and abiotic disturbances. The low availability of nutrients and water, along with the high solar exposure these vegetations experience, impose rigorous environmental filters that affect species distribution. Plant species with structural and functional adaptations can occur in specific locations due to environmental characteristics. We investigated potential variations in the functional leaf traits of congeneric species of Tachigali and Pouteria in different tree community vegetation types in savanna and forest areas in Central Amazon. For this purpose, using standard optical microscopy techniques and statistical models, we analyzed 9 congeneric species, with 3 individuals per species, of woody congeners from Ombrophilous Forest and Amazonian Savanna, both located in the state of Pará, Brazil. Fifteen anatomical traits, both quantitative and qualitative, possessing functional significance were evaluated by comparing tissues between forest and savanna plants, employing ANOVA and ordination analyses. The results indicate that variations in environmental conditions within different vegetation types might be linked to morphophysiological adjustments and strategies in leaves to resist environmental conditions. Species from the Amazonian Savanna present traits more related to conservative characteristics related to water retention and drought resistance, demonstrating a degree of leaf xeromorphism with greater thickness of leaves, palisade parenchyma and epidermal cells. On the other hand, forest species exhibited traits more related to acquisitive and diversified resource strategies, which may be characteristic of the greater availability of light, water and nutrients existing in this environment. The results show considerable variation in leaf traits among forested and savanna formations, and variations in leaf characteristics are expected to be essential for the survival and development of tree species within each type of vegetation.

Holocene histories of biome stability in northern Amazonian savannas

Paleoecological analysis of three lake sediment cores from the Roraima savannas in northern Brazil revealed systems dominated by Poaceae pollen throughout most of the Holocene. A slight increase of palms and woody taxa, probably linked to wetter conditions, is observed during the last 1000 years but is more noticeable after 300 and 150 calibrated years BP (yr BP) respectively. Charcoal was present throughout affirming the importance of fire for the landscape but showed the highest values mostly in the last millenium. Poaceae pollen size spectra varied considerably, showing more variability than the overall pollen record. Despite evidence of some climate change in the Holocene, these savannas were stable systems. The sedimentary records showed gaps in deposition between 10,000 and 7800 yr BP and between 2500 and 1200 yr BP, suggesting dry periods during which lakes most likely dried out or became impermanent and highlighting the sensitivity of these lakes to local water table variation. The establishment of the modern climate in the region is evident after 1000 yr BP.

The pollination ecology of a rare case of bee-pollinated Psittacanthus mistletoe.

The genus Psittacanthus (Loranthaceae) is widely distributed in the Neotropical region, where it is known for its large, colourful, scentless flowers. Until very recently, all Psittacanthus species were regarded as exclusively hummingbird-pollinated and the large species radiation in the genus attributed to the interactions with bird dispersers and pollinators. P. eucalyptifolius (Kunth) G.Don. is the only species reported as bee-pollinated. Here we describe the floral biology, floral visitors, and the reproductive system of P.eucalyptifolius in an Amazonian savanna, Brazil. We also compare the pollination success (reproductive performance) among different Psittacanthus species reported in previous studies. Psittacanthus eucalyptifolius produces sweet-scented flowers, and a small quantity of concentrated nectar. At least five species of scopate bees were recorded visiting and carrying pollen of P. eucalyptifolius. Xylocopa frontalis carried most pollen, visited more flowers, remained longer, and touched reproductive parts of flowers in >95% of the observed visits. Experiments indicate that P. eucalyptifolius is partially autocompatible (39% autonomous pollination) but depends on pollinators to achieve higher performance (~78% in control), indicating that bees can be as effective as birds in pollinating this group of mistletoes.

Ants offset bottom-up control of spiders in Amazonian savanna trees

Community trophic structure is shaped by concurrent bottom-up (resources) and top-down effects (predators), but the extent to which they interact remains uncertain. The Exploitation Ecosystems Hypothesis predicts that predators should offset increases in herbivore abundance with plant productivity, which is supported by data. However, the extent to which interactions within trophic levels (e.g. competition, intraguild predation) have similar effects is less clear. Ants and spiders are abundant in vegetation and consume similar arthropod prey (occasionally each other) and plant exudates, with ants generally showing competitive dominance over spiders. We tested whether ants could shape the trophic structure of tree-dwelling macroarthropod communities by offsetting increases in spider abundance with insect prey. We performed three surveys of the macroarthropod community of 97 trees from two sites in the savanna of Northern Amazonia. Together, ants and spiders represented 74% of the sampled individuals per tree. Insect prey abundance increased with tree crown volume and crown flower cover, consistent with bottom-up limitation. Likewise, both ants and spiders increased with insect prey abundance, with ant abundance also varying with tree species, suggesting reliance on both animal and plant resources. However, as predicted, the positive relationship between spider abundance and insect prey abundance disappeared as ant abundance increased. Our results suggest that agonistic interactions within trophic levels can strongly shape community structure and size by modifying bottom-up effects as much as interactions across trophic levels.

Effects of fire regime on the bird community in an Amazonian savanna

Effects of fire regime on the bird community in an Amazonian savanna

Clarifying the identity of the Cleistes rosea complex (Orchidaceae) based on integrative taxonomy

Cleistes rosea and 10 other taxa comprise a complex widely distributed in various open vegetation types from eastern South America to Panama. The taxonomic identity of most of these taxa is unclear and their relationships with C. rosea have never been satisfactorily discussed or tested. Here, we employ molecular phylogenetics, morphometrics and morphological, ecological and geographic distribution data to investigate the relationships and taxonomy of Cleistes rosea and related species. Our results confirm that Cleistes rosea and Cleistes castaneoides are sister species and although highly similar in general floral morphology, they differ in vegetative characters, distribution, habitat, floral scent, and lip characters. Both species show local variations regarding floral characters, particularly the flower colour, and such differences were used here to delimit infraspecific taxa within the C. rosea/C. castaneoides clade. While C. rosea var. guianensis var. nov. is restricted to French Guiana, and C. rosea var. buenaventurae stat. & comb. nov. is restricted to low altitudes on the western side of the Cordillera Occidental in the Chocó region of Colombia, C. castaneoides var. castaneoides and C. castaneoides var. augusta comb. nov. are sympatric throughout their distribution. Cleistes abdita, formerly known as C. rosea f. pallida, is similar to C. castaneoides but distinguished by the smaller flowers and restricted distribution to Amazonian savannas. Cleistes rosea is distributed throughout the north of the Andes and northern South America. In turn, C. castaneoides occurs mainly in South-eastern and Central-western Brazil. Still, the distribution of these three species overlaps in the Guiana Shield, where the differentiation between them is less evident. Our results provide evidence of the plasticity of the floral morphology of Cleistes, especially the lip, and highlight that hitherto neglected characters, such as vegetative morphology, habitat, and floral scent, are particularly informative for the characterization of species and taxonomy of the genus.

Anatomical traits related to leaf and branch hydraulic functioning on Amazonian savanna plants.

Amazonian savannas are isolated patches of open habitats found within the extensive matrix of Amazonian tropical forests. There remains limited evidence on how Amazonian plants from savannas differ in the traits related to drought resistance and water loss control. Previous studies have reported several xeromorphic characteristics of Amazonian savanna plants at the leaf and branch levels that are linked to soil, solar radiation, rainfall and seasonality. How anatomical features relate to plant hydraulic functioning in this ecosystem is less known and instrumental if we want to accurately model transitions in trait states between alternative vegetation in Amazonia. In this context, we combined studies of anatomical and hydraulic traits to understand the structure-function relationships of leaf and wood xylem in plants of Amazonian savannas. We measured 22 leaf, wood and hydraulic traits, including embolism resistance (as P50), Hydraulic Safety Margin (HSM) and isotope-based water use efficiency (WUE), for the seven woody species that account for 75% of the biomass of a typical Amazonian savanna on rocky outcrops in the state of Mato Grosso, Brazil. Few anatomical traits are related to hydraulic traits. Our findings showed wide variation exists among the seven species studied here in resistance to embolism, water use efficiency and structural anatomy, suggesting no unique dominant functional plant strategy to occupy an Amazonian savanna. We found wide variation in resistance to embolism (-1.6 ± 0.1 MPa and -5.0 ± 0.5 MPa) with species that are less efficient in water use (e.g. Kielmeyera rubriflora, Macairea radula, Simarouba versicolor, Parkia cachimboensis and Maprounea guianensis) showing higher stomatal conductance potential, supporting xylem functioning with leaf succulence and/or safer wood anatomical structures and that species that are more efficient in water use (e.g. Norantea guianensis and Alchornea discolor) can exhibit riskier hydraulic strategies. Our results provide a deeper understanding of how branch and leaf structural traits combine to allow for different hydraulic strategies among coexisting plants. In Amazonian savannas, this may mean investing in buffering water loss (e.g. succulence) at leaf level or safer structures (e.g. thicker pit membranes) and architectures (e.g. vessel grouping) in their branch xylem.

Taxonomic Revision of Cuphea sect. Trispermum s.l. (Lythraceae)

Cuphea sect. Trispermum, one of the 13 sections of the genus, underwent a new circumscription after morphological, ecological, and molecular studies. A total of 20 species and two varieties are recognized in the section, including three new described species (C. araguaiaensis, C. auriflora, and C. praetermissa) and six species transferred from other sections. Eleven taxa were synonymized and 28 lectotypes were designated. The nectary at the base of the ovary deflexed, convex in the dorsal region, concave ventrally, three ovules, obtuse margin seeds, and pollen with the exine thickened between the pores are synapomorphies of C. sect. Trispermum, proving to be monophyletic after a broader definition. Representatives are found in Mexico, Central America, the Caribbean, northern South America, Bolivia, Paraguay, and Brazil, where 17 species occur, of which 13 are endemic. They are subshrubs to shrubs that often grow in cerrado sensu stricto, “campos rupestres” and Amazonian savannas. A high degree of narrow endemism is evident, with species restricted to specialized habitats. New information on floral and vegetative morphology, pollen, cytology, and habitat is provided for the section. In addition, keys are accompanied by descriptions, illustrations, distribution maps, and preliminary assessment of the conservation status for all taxa.

The relative importance of forest cover and patch-level drivers for phyllostomid bat communities in the Amazonian Savannas

ContextAnalyze the multiple dimensions of biodiversity under a local and landscape lens in natural habitats, such as Amazonian savannas, is fundamental for the conservation of species and ecosystems.ObjectivesWe aim to explore how landscape forest cover and patch-level variables affect the patterns of species abundance, functional traits, and taxonomic, functional and phylogenetic α-diversity of Phyllostomid bats in forest patches of the Savannas of Amapá, in both the wet and dry seasons.MethodsWe used mist nets to survey bats in 26 forest patches. We also quantified forest cover in buffers of 500, 1000, 1500, 2000 and 2500 m around each patch, and tree height, basal area, canopy cover, and vegetation clutter in the understorey at the patch level. We used hierarchical partitioning to relate the different indices with our predictor variables.ResultsTaxonomic, functional and phylogenetic diversity in the wet season increased with the proportion of forest cover in the 2500 m buffer. Vegetation clutter was negatively related to taxonomic and functional diversity in the wet season. In the dry season, average tree height positively affected taxonomic and functional diversity. Patch-level variables were more important than forest cover in explaining the average functional traits in both seasons.ConclusionWe found seasonal variation in the relationships between components of bat diversity and different drivers. Since both forest cover in the landscape and patch-level variables are important for Phyllostomid bat diversity, conservation plans should consider forest conservation at the landscape level and maintenance of forest patch quality.

Flesh Flies (Diptera: Sarcophagidae) From the Brazilian Amazonian Savannas, a Poorly Sampled and Threatened Environment.

The Amazonian region is composed by many kinds of environments, including the Amazonian savannas, which comprise about 5% of the Amazon biome in Brazil. The biota of Amazonian savannas is poorly known, especially for insects. In this study, we performed a faunistic inventory of flesh flies (Diptera: Sarcophagidae) of four Brazilian Amazon savannas, where we recorded two subfamilies, 16 genera, and 40 species, two of which are described as new to science: Lepidodexia (Notochaeta) helenae sp. nov. and Lipoptilocnema augustoi sp. nov. Oxysarcodexia graminifoliaSouza, Pape & Thyssen, 2020 is recorded for the first time for Brazil. Dexosarcophaga paulistanaLopes (1982), Helicobia biplagiataDodge, 1966, Helicobia cearensisTibana, 1976, Oxysarcodexia simplicoides (Lopes, 1933), and Oxyvinia excisa (Lopes, 1950) are newly recorded for the Brazilian Amazon. Oxysarcodexia nitidaSoares & Mello-Patiu, 2010 is a new record for the state of Pará. The species D. paulistana is redescribed, and photographs and detailed illustrations of male terminalia are provided.

A comparative phylogenomic analysis of birds reveals heterogeneous differentiation processes among Neotropical savannas.

The main objective of this study was to evaluate biogeographical hypotheses of diversification and connection between isolated savannas north (Amazonian savannas) and south (Cerrado core) of the Amazon River. To achieve this, we used genomic markers (genotyping-by-sequencing) to evaluate the genetic structure, population phylogenetic relationships and historical range shifts of four Neotropical passerines with peri-Atlantic distributions: the narrow-billed woodcreeper (Lepidocolaptes angustirostris), the plain-crested elaenia (Elaenia cristata), the grassland sparrow (Ammodramus humeralis) and the white-banded tanager (Neothraupis fasciata). Population genetic analyses indicated that landscape (e.g., geographic distance, landscape resistance and percentage of tree cover) and climate metrics explained divergence among populations in most species, but without indicating a differential role between current and historical factors. Our results did not fully support the hypothesis that isolated populations in Amazonian savannas have been recently derived from the Cerrado core domain. Intraspecific phylogenies and gene flow analyses supported multiple routes of connection between the Cerrado and Amazonian savannas, rejecting the hypothesis that the Atlantic corridor explains the peri-Atlantic distribution. Our results reveal that the biogeographical history of the region is complex and cannot be explained by simple vicariant models.

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.

Mabea dalyana (Euphorbiaceae-Hippomaneae): a new subshrub with xylopodia endemic to the savannas of the Brazilian Amazon

During fieldwork in the Campos Amazônicos National Park, Amazonas state, Brazil, a new endemic species of Mabea was collected in savanna areas. Field collections and specimens in RON, MG, and HRCB were analyzed. To understand the species distribution and verify possible areas of occurrence, niche modeling was conducted using the sdm package in R. Mabea dalyana, the new species is a subshrub with xylopodia and reduced size (less than 1 m height) and small, yellow thyrses. There are several allopatric species of Mabea growing in Amazonian savannas, some widespread but others locally restricted, such as M. uleana from central Amazonia that has some superficial resemblance in leaves and inflorescences but can be distinguished from M. dalyana by pubescent adaxial leaf surface (vs. glabrous), 12-21 submarginal glands (vs. 10 submarginal glands), thyrse brownish to red (vs. yellow thyrse) and conspicuous caruncle (vs. caruncle inconspicuous). M. dalyana is endemic to hyperseasonal savanna, very well adapted to savanna, and fire tolerant. It has notable characteristics, such as a subshrub habit, a xylopodium, glabrous leaves, and sepals noticeably larger than the ovary.

Bird species responses to forest-savanna boundaries in an Amazonian savanna

De Sousa, J. Cleiton, J. Julio Toledo, W. Douglas Carvalho, and J. Cardoso da Silva. 2022. Bird species responses to forest-savanna boundaries in an Amazonian savanna. Avian Conservation and Ecology 17(1):30. https://doi.org/10.5751/ACE-02138-170130

Priority areas for conservation of primates in a threatened Amazonian savanna

Primates are globally recognized as an important component of biodiversity, however, more than half of primate species in the world are threatened and agriculture expansion is one of the main threats. Brazil has one of the largest networks of protected areas (PAs) in the world, but there are some conservation gaps, such as the Amazonian savannas. We aim to identify a network of priority areas to conserve a Brazilian Amazonian savanna highly threatened by agriculture expansion, by using seven primate species and four vegetation types as targets. We constructed species distribution models (SDMs) for the primates and used a Systematic Conservation Planning approach. We defined as a quantitative conservation target the proportion of the distribution of each primate species within the network according to traits related to their vulnerability to extinction. In addition, we set a target of including at least 30% of each savanna type within priority areas. We created a map of potential use of the land for agriculture and another of environmental risk, which were included as costs in the decision process, and together with the SDMs and vegetation types, identified the network of priority areas by using the software Marxan. We evaluated the feasibility of implementing conservation actions, such as establishing Conservation Units (e.g. reserves managed by the government), or implementing community-based conservation actions in each priority area. Additionally, we estimated the economic investment (US$/year) required to establish Conservation Units across the priority areas. Conservation targets for primates and vegetation types were met by protecting 3,240 km2 of the Savannas of Amapá. An investment of approximately US$958,122/year over five years is required to turn these priority areas into Conservation Units, however, we propose other strategies such as conservation on community lands and public policies. All these strategies would allow for protecting forest cover and the heterogeneous environments that are suitable for primates and other biodiversity components.

Composition, richness and nestedness of gallery forest bird assemblages in an Amazonian savanna landscape: lessons for conservation.

Gallery forests are important to the maintenance of a substantial portion of the biodiversity in neotropical savanna regions, but management guidelines specific to this forest type are limited. Here, we use birds as study group to assess if: (1) functional traits can predict the abundance and occupancy of forest species within a savanna landscape, (2) habitat structures influence the taxonomic, functional, and phylogenetic diversity of forest assemblages, and (3) less diverse gallery forest assemblages are a nested subset of more diverse assemblages living near continuous forests. Then, we propose strategies on how gallery forests can be managed to maintain their species assemblages amidst the fast expansion of human activities across tropical savanna landscapes. We studied 26 sites of gallery forests in an Amazonian savanna landscape and found that: (1) habitat specificity is the only functional trait that predicts species abundance and occupancy across a landscape; (2) phylogenetic diversity is negatively correlated with understory foliage density; (3) the percentage of forests and savannas around sites is positively correlated with both phylogenetic and functional diversity; (4) increasing human activities around gallery forest negatively influences taxonomic and functional diversity; and (5) forest bird assemblages are not distributed at random across the landscape but show a nested pattern caused by selective colonization mediated by habitat filtering. Our combined findings have three implications for the design of conservation strategies for gallery forest bird assemblages. First, maintaining the connectivity between gallery forests and adjacent continuous forests is essential because gallery forest bird assemblages are derived from continuous forest species assemblages. Second, because most species use the savanna matrix to move across the landscape, effectively managing the savanna matrices where gallery forests are embedded is as important to maintaining viable populations of forest bird species as managing the gallery forest themselves. Third, in savanna landscapes planned to be used for agriculture production, protecting gallery forests alone is not enough. Instead, gallery forests should be protected with surrounding savanna buffers to avoid the detrimental effects (edge effects and isolation) of human activities on their biodiversity.

Corrigendum: Necromys lasiurus: Lessons From a 38-Year Study in an Amazonian Savanna

Corrigendum on: Rosa CA, Ganança PHS, Lima AP and Magnusson WE (2021) Necromyslasiurus: Lessons From a 38-Year Study in an Amazonian Savanna. Front. Ecol. Evol. 9:716384.doi: 10.3389/fevo.2021.716384.Incorrect Funder NameThere is an error in the Funding statement. The correct Name of one of the Funders is**Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) - PROEX n.0742/2020**. The authors apologize for this error and state that this does not change thescientific conclusions of the article in any way. The original article has been updated.The correct Funding section is below.“In the last 3 years the data collection was financed by PELD (LTER)-POPA through the ConselhoNacional de Desenvolvimento Científco e Tecnológico (CNPq), grant number 441443/2016-8.Over the 20 years, INPA PPI-PRJ-1223 financed travel for AL. CNPq grants 446208/2015-9,401120/2016-3, and 401327/2012-4 financed field assistants and material throughout the study.This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de NívelSuperior – Brasil (CAPES) – PROEX n. 0742/2020, for PHSG (Ph.D. scholarship)”.Incorrect Author NameAn author name was incorrectly spelled as **Clarisa Alves Rosa**. The correct spelling is**Clarissa Alves da Rosa**. The authors apologize for this error and state that this does notchange the scientific conclusions of the article in any way. The original article has been updated.