White-sand Forests Research Articles

A new data-driven map predicts substantial undocumented peatland areas in Amazonia

Abstract Tropical peatlands are among the most carbon-dense terrestrial ecosystems yet recorded. Collectively, they comprise a large but highly uncertain reservoir of the global carbon cycle, with wide-ranging estimates of their global area (441 025–1700 000 km2) and below-ground carbon storage (105–288 Pg C). Substantial gaps remain in our understanding of peatland distribution in some key regions, including most of tropical South America. Here we compile 2413 ground reference points in and around Amazonian peatlands and use them alongside a stack of remote sensing products in a random forest model to generate the first field-data-driven model of peatland distribution across the Amazon basin. Our model predicts a total Amazonian peatland extent of 251 015 km2 (95th percentile confidence interval: 128 671–373 359), greater than that of the Congo basin, but around 30% smaller than a recent model-derived estimate of peatland area across Amazonia. The model performs relatively well against point observations but spatial gaps in the ground reference dataset mean that model uncertainty remains high, particularly in parts of Brazil and Bolivia. For example, we predict significant peatland areas in northern Peru with relatively high confidence, while peatland areas in the Rio Negro basin and adjacent south-western Orinoco basin which have previously been predicted to hold Campinarana or white sand forests, are predicted with greater uncertainty. Similarly, we predict large areas of peatlands in Bolivia, surprisingly given the strong climatic seasonality found over most of the country. Very little field data exists with which to quantitatively assess the accuracy of our map in these regions. Data gaps such as these should be a high priority for new field sampling. This new map can facilitate future research into the vulnerability of peatlands to climate change and anthropogenic impacts, which is likely to vary spatially across the Amazon basin.

A new species of terrestrial foam-nesting frog of the Adenomera simonstuarti complex (Anura, Leptodactylidae) from white-sand forests of central Amazonia, Brazil

By using integrative taxonomy, we describe a new species of terrestrial foam-nesting frog of the genus Adenomera from white-sand forests of the Rio Negro Sustainable Development Reserve, Central Amazonia, Brazil. Within the A. andreae clade, the new species belongs to the A. simonstuarti complex where it is sister to the lineage from the lower Juruá River. The new species is assigned to the genus Adenomera by having adult SVL smaller than 34.1 mm, by its lack of fringing and webbing between toes and by the absence of spines on the thumb of adult males. It differs from other Adenomera by the following combination of characters: antebrachial tubercle absent; toe tips flattened or slightly flattened, with visible expansions; nearly solid, dark-coloured stripe on underside of forearm; single-note advertisement call; notes formed by 11–21 incomplete pulses; call duration varying between 100 and 199 ms; fundamental frequency 1,765–2,239 Hz; dominant frequency 3,448–4,349 Hz; and endotrophic tadpoles with spiracle present and labial teeth absent. Over the last decade, we have inventoried many permanent sampling modules in ombrophilous forests in the Manaus Region and in the Purus-Madeira interfluve, but the new species was found only in the white-sand forest from West Negro-Solimões Interfluve. Adenomerasp. nov. may be endemic to, or at least a specialist in, this environment.

Conservation of tree phylogenetic diversity in the Brazilian Atlantic Forest: Dry habitats matter

Conservation assessments that aim to represent the pool of lineages that exist within a region are challenging due to incomplete knowledge of the spatial distribution and environmental preferences of distinct lineages. In this context, community-level models represent a powerful tool that can be used to predict spatial variation in phylogenetic composition. If lineages composition and habitat loss present a non-random spatial pattern within a region, we can expect that some lineages are more threatened by habitat loss than others. To test this hypothesis we combined multivariate analysis and a modelling approach to predict the phylogenetic composition of angiosperm tree/shrub communities in Rio de Janeiro State, southeastern Brazil, which is regarded as a plant endemism center within the Brazilian Atlantic forest biome. Then we correlated the resulting models with maps of vegetation cover and protected areas, to identify lineages subjected to higher habitat loss and clades that receive less protection. We found that angiosperm tree/shrub lineages are highly structured across distinct vegetation types and that a gradient of deforestation and land protection parallels the phylogenetic gradient formed by the distinct vegetation types. Consequently, some vegetation types and its associated angiosperm lineages are much more threatened by habitat loss and are less protected than others. Specifically, Ericales (asterids), Caryophyllales and Santalales are the most threatened clades in this region, along with their preferred habitats, seasonal forests and coastal white-sand forests (restingas). Protecting and restoring these dry habitats is critical for the conservation of tree and shrub phylogenetic diversity in the Brazilian Atlantic forest.

A new species of Pristimantis (Anura: Strabomantidae) from white-sand forests of central Amazonia, Brazil.

The white-sand ecosystems in the Solimões-Negro Interfluve are among the less studied in Amazonia. Recent herpetological surveys conducted west of Manaus, Brazil (central Amazonia) indicate that white-sand forests host a unique anuran fauna comprising habitat specialized and endemic species. In the present study we describe a new species of rain frog belonging to the Pristimantis unistrigatus species group from the white-sand forest locally called "campinarana" (thin-trunked forests with canopy height below 20 m). The new species is phylogenetically close to rain frogs from western Amazonian lowlands (P. delius, P. librarius, P. matidiktyo and P. ockendeni). It differs from its closest relatives mainly by its size (male SVL of 17.3-20.1 mm, n=16; female SVL of 23.2-26.5 mm, n=6), presence of tympanum, tarsal tubercles and dentigerous processes of vomers, its translucent groin without bright colored blotches or marks, and by its advertisement call (composed of 5-10 notes, call duration of 550-1,061 ms, dominant frequency of 3,295-3,919 Hz). Like other anuran species recently discovered in the white-sand forests west of Manaus, the new species seems to be restricted to this peculiar ecosystem.

Two new surprising species of leaf-litter toad of the Rhinella margaritifera species group (Anura: Bufonidae) from the Peruvian Amazon, LoretoPeru.

We describe two new species of Rhinella (Anura: Bufonidae) from the department of Loreto, Peru. We integrate morphological and phylogenetic analyses to provide evidence of new species. R. angeli sp. nov. is diagnosable from all congeners by its pronounced fleshy proboscis and R. unapensis sp. nov. by the small size (mean snout-vent length=37.7 4.1 mm) of adult males, snout pointed in dorsal view, nearly acute in lateral view, and small bony protrusion at the angle of jaws among other characters. The two species are allopatric, where the first species is known to be associated inhabits upland (=terra firme) forests, while the second white sand forests (=varillales) around Iquitos city. The two new species represent the 20th and 21st species of the Rhinella margaritifera species group.

A NewMasdevallia(Pleurothallidinae: Orchidaceae) from the White-Sand Forests of the Central Amazon, Brazil

Abstract—Masdevallia britoi, a new species inMasdevalliasect.Minutae, is described and illustrated from the central Amazon in Brazil. It is similar toM. wendlanianabut differs by shorter sepals that are internally white, shorter oblong petals with a delicate tooth near the middle, shorter lip with deltoid marginal folds near the middle and three-denticulate apex, and shorter ovary. The new species grows in the white-sand forests locally known with the name Campinaranas. We also provide an identification key for the species ofMasdevalliafrom the Brazilian Amazon.

A NEW SNOUTED TREEFROG OF THE GENUS SCINAX (ANURA, HYLIDAE) FROM THE WHITE-SAND FORESTS OF CENTRAL AMAZONIA

We describe through integrative taxonomy a new species of snouted treefrog of the genus Scinax from white-sand forests of the Rio Negro Sustainable Development Reserve in Central Amazonia, Brazil. The new species is phylogenetically related to other Scinax with striped eyes and pulsed advertisement calls. It differs from other Amazonian species mainly by having snout–vent length 21.6–25.4 mm (n= 11) in adult males and 24.8–27.0 mm (n= 9) in females, snout subacuminate in dorsal view, a dark brown lateral stripe on each flank (fading posteriorly), brown tadpoles with labial keratodont row formula 2(2)/3 and keratodont row P-2 longer than P-1 and P-3, and an advertisement call consisting of a single pulsed note with a call duration of 502–652 ms, 79–105 pulses/note and a dominant frequency of 3,811–4,543 Hz. The new species clusters within a major, well-supported phylogenetic clade grouping several candidate and recently described species as well as species previously included in the former Scinax staufferi species group (viz., S. cruentomma, S. fuscomarginatus, S. staufferi, and S. wandae). The phylogenetic relationships and structural pattern in the advertisement calls of these species highlight the need for a redefinition and reevaluation of the monophyly of the S. staufferi species group.

A new species of nurse-frog (Aromobatidae, Allobates) from the Amazonian forest of Loreto, Peru.

We describe a new species of nurse-frog (Aromobatidae, Allobates) from the Amazonian forest of Loreto, Peru using morphological, acoustic and genetic data. Our phylogenetic analysis placed Allobates sieggreenae sp. nov. as the sister species of A. trilineatus, the most similar-looking species and with which it was previously confused. However, the new species has a brown dorsum, solid dark brown lateral dark stripe not fading towards groin, adult males with few and sparse melanophores over a cream background on chin, chest, and belly, dark transverse bars absent on thighs, and an advertisement call formed by a trill of single notes (in A. trilineatus dorsum dark brown, blackish brown lateral dark stripe, paler from mid-body to groin, adult males with a dark background color on chin, chest, and belly due to a dense layer of melanophores, dark transverse bar present on dorsal surface of thighs, and trills of paired notes). Allobates sieggreenae is known from two localities of Amazonian white-sand forest ecosystems east of the Ucayali River.

Effects of selective-logging, litter and tree species on forests in the Peruvian Amazon: seed predation, seed pathogens, germination

Background: The Amazon basin contains mainly unflooded forests, and they are among the most important ecosystems in the world. Field experiments on seed processes are very important in order to understand the structure, function and dynamics of these forests. Methods: And so tree seeds of three species (Cecropia latiloba, Guarea macrophylla, Socratea exorrhiza) were set out in Amazon unlogged terra firme forest, in Amazon selectively-logged terra firme forest, in Amazon palm forest, and in Amazon white sand forest either on top of or beneath the litter layer, and after two weeks scored for seeds taken by predators, seeds destroyed by pathogens and seeds that germinated. Results: I found both terra firme forests (unlogged and selectively-logged) lost most of their seed to predators and the least of their seed to pathogens, white sand forests lost the least of their seed to predators and the most of their seed to pathogens, and the fewest seeds germinated in both terra firme forests and in palm forest. More specifically (1) within unlogged terra firme forest addition of litter reduced seed predation but increased seed losses to pathogens and germination, and C. latiloba lost the most seeds to pathogens, (2) within selectively-logged terra firme forest seeds showed the same trends as unlogged terra firme forest but without significant effects, (3) within palm forest addition of litter reduced predation but increased losses to pathogens, and S. exorrhiza lost the least seeds to pathogens, and (4) within white sand forests addition of litter increased germination. Combining the results from all forests together, predators took most of the seeds, pathogens took most of the seeds that escaped predation, and most of the seeds that survived predation and pathogens germinated. Conclusion: While such large losses of tree seed to predators and pathogens in these unflooded forests suggest limited recruitment, the variation demonstrated in these field experiments – among forest-types, among tree species, between litter situations on the forest floor – help to insure that recruitment does occur and that these unflooded forests continue to dominate the Amazon basin.

Intensive field sampling increases the known extent of carbon-rich Amazonian peatland pole forests

Peatland pole forest is the most carbon-dense ecosystem in Amazonia, but its spatial distribution and species composition are poorly known. To address this knowledge gap, we quantified variation in the floristic composition, peat thickness, and the amount of carbon stored above and below ground of 102 forest plots and 53 transects in northern Peruvian Amazonia. This large dataset includes 571 ground reference points of peat thickness measurements across six ecosystem types. These field data were also used to generate a new land-cover classification based on multiple satellite products using a random forest classification. Peatland pole forests are floristically distinctive and dominated by thin-stemmed woody species such as Pachira nitida (Malvaceae), Platycarpum loretense (Rubiaceae), and Hevea guianensis (Euphorbiaceae). In contrast, palm swamps and open peatlands are dominated by Mauritia flexuosa (Arecaceae). Peatland pole forests have high peat thickness (274 ± 22 cm, mean ± 95% CI, n = 184) similar to open peatlands (282 ± 46 cm, n = 46), but greater than palm swamps (161 ± 17 cm, n = 220) and seasonally-flooded forest, terra firme, and white-sand forest where peat is rare or absent. As a result, peatland pole forest has exceptional carbon density (1,133 ± 93 Mg C ha−1). The new sites expand the known distribution of peatland pole forest by 61% within the Pastaza-Marañón Foreland basin, mainly alongside the Tigre river, to cover a total of 7540 km2 in northern Peruvian Amazonia. However, only 15% of the pole forest area is within a protected area, whilst an additional 26% lies within indigenous territories. The current low levels of protection and forest degradation but high threat from road paving projects makes the Tigre river basin a priority for conservation. The long-term conservation of peatland pole forests has the potential to make a large contribution towards international commitments to mitigate climate change.

Gongylolepis martiana, an Asteraceae pollinated by bats in the Amazon.

Most Asteraceae species are pollinated by insects, mainly bees and butterflies, although pollination by birds has been documented and pollination by bats has been suggested for some species. Here, we investigated the pollination of Gongylolepis martiana, a species supposedly pollinated by bats. We assessed floral traits and visitors in a population of G. martiana in the Brazilian Amazon, measuring pollen removal from anthers and deposition on stigmas by diurnal and nocturnal visitors. Florets opened at dusk and lasted for 4days, with the male phase starting on the first night and the female phase on the third night. Accumulated nectar per capitulum was 69.6μl per night and sugar concentration was 15%. Nectar-feeding bats and hummingbirds contacted the sexual parts, but pollen removal and deposition were greater throughout the night than during the day, when Meliponini bees considerably reduced pollen availability. Other nocturnal visitors of G. martiana were rare, including nocturnal bees and moths that foraged for pollen and nectar, respectively. Our results support that nectarivorous bats are the main pollinators of G. martiana, confirming Vogel's hypothesis of bat pollination in Asteraceae, particularly in the genus Gongylolepis. Since anthesis and each sexual floral phase started in the evening, nectarivorous bats and diurnal bees caused additive priority effects, preventing hummingbirds from being efficient pollinators. The high density of flowering individuals of G. martiana in patches from white-sand forests likely increases bat attraction, while the small amount of nectar per plant favours cross-pollination.

Taxonomic synopsis of Leguminosae subfamilies Cercidoideae, Detarioideae, and Dialioideae in the National Forest of Caxiuanã, Pará, Brazil

We conducted a floristic study in the National Forest of Caxiuanã (FLONA Caxiuanã) located in the state of Pará, Brazil, in the municipalities of Portel and Melgaço. This forest is characterized by Amazonian physiognomies such as lowlands, seasonally flooded areas (várzea and igapó), Amazonian white-sand scrub (campinarana) and secondary forests. This article provides a taxonomic synopsis of the members of the Leguminosae subfamilies Cercidoideae, Detarioideae, and Dialioideae that occur in the FLONA Caxiuanã, based on herbarium studies and field expeditions. Nineteen species were catalogued, including two members of Cercidoideae, 16 of Detarioideae, and one of Dialioideae. The species of Cercidoideae from FLONA Caxiuanã are restricted to the Amazon forest, and one of them is exclusive to the Brazilian Amazon. Of the species of Detarioideae, 81.25% are restricted to the Amazon forest and 25% are exclusive to the Brazilian Amazon. The single species of Dialioideae is restricted to the Amazon forest. The most species-rich genera belong to Detarioideae: Macrolobium (six species). The two members of Cercidoideae and the only Dialioideae species occur in terra firme forest; the 56.25% species of Detarioideae occur in igapó forests. We include an identification key for the species presented in the synopsis, with illustrations, diagnoses, and taxonomic comments for all catalogued species.

A comparative study of temporal variation of two epiphytic bryophytes in a central Amazonian white-sand forest, Brazil

ABSTRACT We evaluated the local population dynamic of two epiphytic species, Syrrhopodon helicophyllus and Thysananthus amazonicus, over six years from 2014-2020, both before and after the fire event which occurred in the white-sand forest (Campinarana) located in Central Amazon. We did not observed an overall differences on colony abundance on the host tree over time before the fire event in 2019. However, colony abundances shifts along the vertical gradient towards mesic microenvironment which allow to persist during the El Niño event of 2015-2016, and recovered in the following years. Moreover, we observed that colonies of both bryophyte speciesdrastically declined after the fire event in 2019, leading to a complete loss of the species in some of the host tree studied. The direct impacts of climate change with an increased fire and drought events in Central Amazon forests will result in the loss of epiphyte local biodiversity, especially in the unique isolated white-sand forests.

First record of the gray-legged tinamou, Crypturellus duidae, and other poor-soil specialist birds from peatlands in the Putumayo River basin, Loreto, Peru

ABSTRACT Crypturellus duidae (Tinamidae) is a poor-soil specialist with isolated populations in Amazonia, and is considered restricted to white-sand forest habitats. We report the first record of C. duidae in a peatland forest in northern Peru, in the Putumayo River basin. Our record extends the known distribution of C. duidae between two disjoint areas of occurrence in Peru and Colombia, and shows its presence in peatland forest, another forest type on nutrient-poor soils. Additionally, we report the presence of other poor-soil specialist bird species that were previously registered in peatlands. Together with the new record of C. duidae, these bird records provide evidence of the diversity of poor-soil specialists in peatland forests.

<p><strong>A new arborescent <em>Chamaecrista</em> (Leguminosae) from Amazon, Brazil</strong></p>

Chamaecrista ipanorensis, a new arborescent species of caesalpinioid legume restricted to campinarana vegetation (white sand forest) in upper Rio Negro, northern Amazon basin, is described, illustrated, and compared with the morphologically similar species C. hymenaeifolia and C. polystachya.

Effect of Structural Variation of Dead Trunks on Passalid (Coleoptera: Passalidae) Assemblages in Central Amazonian Campinaranas.

The present study investigated the occurrence of passalids in dead trunks with structural variations. Trunks were found in areas of white sand forests, locally known as Campinarana, in the state of Amazonas, Brazil. The collections were extended from May to December 2009. The mean diameter of the trunks and their stage of decomposition were classified, and the species of Passalidae were classified according to the location of their galleries. We used multiple generalized models to investigate the relationship between abundance and permutational multivariate analysis of variance (PERMANOVA) to investigate the relationships between predictors and passalid composition. A total of 361 passalids belonging to 13 species were collected from 11 tree species, of which Aldina heterophylla represented the highest proportion of logs (55%). Only the diameter of the trunk was related to the abundance of species, with trunks of larger diameters presented more individuals. The passalid composition was correlated with the diameter and decomposition of the trunks of all species of trees and only with the diameter of the trunks of A. heterophylla. Most of the species collected in Campinaranas construct their galleries in two or more regions of the trunk. The region that supported a greater number of colonies was the sapwood, followed by the inner bark and the soil-stem interface. The general habit of passalids found may be advantageous, probably to compensate for the low dispersion and isolation in areas with low availability of resources, such as Campinaranas forests in the Amazon.

Rediscovery of Osteocephalus vilarsi (Anura: Hylidae): an overlooked but widespread Amazonian spiny-backed treefrog.

Osteocephalus vilarsi (Melin, 1941) is an Amazonian treefrog species known for over 75 years from its holotype only. Due to a lack of published data on its morphological diagnostic characters and their variations, as well as the absence of molecular, acoustic and ecological data supporting its identity, a highly dynamic taxonomic history has led this species to be confused and even synonymised with other Osteocephalus species from distinct species groups. The molecular phylogenetic relationships of O. vilarsi were investigated based on recently collected specimens from eight Northwestern Brazilian localities in the state of Amazonas, leading to its removal from the Osteocephalus taurinus species group and placement in the Osteocephalus planiceps species group. Furthermore, detailed data on morphology and colour variation are provided, as well as advertisement call and tadpole descriptions. Finally, the currently known geographic range of O. vilarsi is considerably extended, first data on the natural history of the species are provided, and the possible ecological preference of O. vilarsi for Amazonian white-sand forests is discussed.

Logging impact on Amazonian white-sand forests: perspectives from a sustainable development reserve

ABSTRACT Overexploitation is one of the main causes of biodiversity loss and local extinction. In the Brazilian Amazon, the intensive use of high-value timber species is leading to a decline in their populations. When in decline, these species can be replaced by less valuable and more common ones that are more feasible to exploit. We conducted interviews with residents of two communities in a sustainable development reserve in central Amazonia, and used free lists and the cognitive salience index (S) to assess the perceptions of residents regarding the occurrence and purpose of timber exploitation, and to identify possible endangered species in white-sand and terra-firme forests. In addition, to infer possible consequences of logging, we assessed the current population status of timber species cited by residents in forest-plot inventories carried out within the reserve. S-index values and interviewee reports suggested an intensive use of terra-firme timber species and an apparently recent increase in the exploitation of white-sand species, which did not use to be exploited because of their relatively low commercial value. The inventories showed that the white-sand timber species have high relative densities and low S values in contrast to the terra-firme species, which mostly have low relative densities and high S values. Our results highlight the need to identify and monitor relevant timber species in both terra-firme and white-sand forests, and to increase the involvement of the local community in the development of logging management practices.

Carbon content and pH as important drivers of fungal community structure in three Amazon forests

Amazonia comprises a mosaic of ecosystems that harbor high biodiversity. Knowledge about fungal diversity and ecology in this region remains very limited. Here, we examine soil fungal communities in forests of the Colombian Amazonia and their relationship to important edaphic variables. Fungal communities were studied in terra-firme forests dominated by arbuscular mycorrhizal (AM) trees, terra-firme forests with the ectomycorrhizal (EcM) tree Pseudomonotes tropenbosii (Dipterocarpaceae), and white sand forests (WSF) with the EcM host plant genera Dicymbe and Aldina (Fabaceae). Fungal community composition was determined through 454-pyrosequencing of the ITS2 region of ribosomal DNA. We established the impact of the type of forest and edaphic parameters in structuring the fungal communities. We found a high diversity of fungi with 2,507 OTUs occurring in the soil samples studied. Carbon content and pH were the main edaphic factors contributing to structure the fungal community across all forests. Fungal community composition differs among terra-firme plots and WSF, while it was similar among AM and EcM-dominated areas in terra-firme. Our results revealed an important EcM fungal diversity in terra-firme AM-forests, where some EcM plants such as the ones in the genera Coccoloba and Neea occur scattered within an AM-matrix. This is a first approximation to understand the ecology of soil fungal communities in forests of the Colombian Amazonia. We found that fungal soil communities have a spatial variation related to forest type (terra-firme and WSF), soil pH, and soil carbon content. Due to the strong correlation between vegetation and soil fertility in Amazonia, it is difficult to understand the effects of those factors to the fungal communities.

Use of autonomous audio recordings for the rapid inventory of birds in the white-sand forests of the Peruvian Amazon

White-sand forests are patchily distributed ecosystems covering just 5% of Amazonia that host many specialist species of birds not found elsewhere, and these forests are threatened due to their small size and human exploitation of sand for construction projects. As a result, many species of birds that area white-sand specialists are at risk of extinction, and immediate conservation action is paramount for their survival. Our objective was to evaluate current survey methods and determine the relative effect of the size of patches these forests on the presence or absence of white-sand specialist. Using point counts and autonomous recorders, we surveyed avian assemblages occupying patches of white-sand forest in the Peruvian Amazon in April 2018. Overall, we detected 126 species, including 21 white-sand forest specialists. We found that autonomous recorders detected significantly more species of birds per survey point than point counts. We also found a negative relationship between avian species richness and distance from the edge of patches of white-sand forest, but a significant, positive relationship when only counting white-sand specialists. While autonomous recorders detected more overall species, point counts were more effective for detecting canopy-dwelling passerines. Therefore, we recommend that inventories and surveys for rare and patchily distributed species in the tropics use a mixed-methods survey technique of bioacoustics and visual observations. Finally, conserving large, continuous patches of white-sand forest may increase survival likelihood for white-sand specialists, but future studies determining habitat occupancy should further investigate this relationship.