Fungi play an important role in litter decomposition in forest ecosystems and are considered an undersampled group in the Amazon biome. This study aims to describe the composition, richness and ...frequency of species of conidial fungi associated with palm trees in an area of the Amapá National Forest, State of Amapá, Brazil. Palm leaf litter was collected from July 2009 to June 2010, incubated in moist chambers and examined for the presence of fungi. One hundred and seven species of conidial fungi were identified, in 79 genera and 25 families. As for the relative frequency of the species, the majority (94.4%) was sporadic and occurred on leaflets. We report new records for South America (Chaetopsis intermedia, Chaetochalara laevis and Thysanophora verrucosa) and Brazil (Chloridium phaeosporum, Helminthosporiella stilbacea and Zygosporium geminatum), and 83 for the State of Amapá, while 15 are also new for the Brazilian Amazon. This study significantly increases the knowledge about the distribution of the fungal species in the Amazon biome, and emphasizes the importance of the conservation of these organisms particularly in view of the large number of sporadic species recorded.
Context
Island Biogeography Theory and Habitat Amount Hypothesis postulate species richness and densities to increase with connectivity and habitat amount, while niche theory highlights the ...importance of environmental heterogeneity for species coexistence. Additional ecological niches in heterogeneous landscapes increase species richness and functional and phylogenetic diversity, but larger, less isolated habitats are expected to enlarge species densities by mass effects without effects on functional or phylogenetic diversity.
Objectives
We assessed the relative contribution of habitat amount, isolation and environmental heterogeneity on taxonomic, functional and phylogenetic diversity of the particular
canga
vegetation, i.e., rupestrian savannas associated to banded ironstone outcrops from the Carajás Massif, Eastern Amazon.
Methods
We sampled vegetation at 48 sampling points comprising different physiognomies from 5
canga
patches. Diversity measures were modelled as response variables in linear mixed models, using non-collinear predictors of habitat amount, isolation and environmental heterogeneity.
Results
Diversity and species composition differed among
canga
physiognomies, indicating that environmental filters segregate
canga
plant metacommunity in physiognomy-specific species pools. Landscape roughness, a proxy for heterogeneity on the landscape level, increases species densities and functional richness. Additionally, habitat amount was positively associated with the degree of phylogenetic relatedness and functional diversity in communities.
Conclusions
Our results suggest that configurational landscape heterogeneity increases the number of available ecological niches, while larger habitat amounts select for functionally and phylogenetically convergent species. These different underlying mechanisms need to be considered for management plans and reserve design for
canga
ecosystems, so that functional
canga
portions can be protected.
Climate changes have become undisputed, as have their consequences for global ecosystems and mankind. The coastal areas are among the most affected areas on the planet due to their geographical ...location. The effects suffered by coastal areas can render the residing populations homeless, as well as compromise the continuity of the history and culture of these environments. The Marine Extractive Reserve of the city of Soure (coastal area of eastern Amazonia) stands out for housing populations that have developed an intimate relationship with nature and have knowledge that can explain people's perception of climate changes. In this context, this study investigated how local residents perceive climate change and its consequences considering different temporal and spatial scales. To this end, questionnaires were developed and applied using a 5-point Likert scale. Our results indicate that perception is shaped by socioeconomic and demographic factors, and that they are perceived on different time scales and geographic space. These findings reflect the awareness-raising efforts of the management body of this Conservation Unit and the local knowledge, derived from the relationship of the residents with the natural environment, which, together, provided the population with assertive information that favor a better understanding of this phenomenon.
•The environmental perceptions are shaped by community age and geographic distance.•Climate change perceptions are tied to expectations of the future.•Climate change is understood at different temporal and spatial scales.
Abstract Astrocaryum vulgare Mart. is a palm tree that tolerates multiple environmental conditions, with complex development characteristics. The objective is to understand the population structure, ...the spatial distribution of this species in different environments and the effect of environmental gradients on its occurrence on Marajó Island, Pará. The hypothesis is that the population density of the species, as well as the spatial distribution, depends on the environment in which it is inserted. The study was carried out in 11 communities of residents of five different physiognomies, in which all individuals belonging to 42 sample units were mapped, measured and were categorized in height classes for further analysis. The results showed an abundance of juvenile individuals and a spatial distribution grouped across all physiognomies. The evidence points to a growing population, probably influenced by anthropic actions. Variables such as vegetation index of normalized difference, slope and distance from rivers were shown to be linked to the development of morphological characteristics. Finally, the occurrence of this species in physiognomies may be linked to the land use system, as it contributes to the creation of favorable environments for its development and, although differently, it has shown a high degree of adaptation to atypicals.
Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and ...space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost.
Display omitted
•Ecological metadata were compiled for 7,694 sites across the Brazilian Amazon•Accessibility and proximity to research facilities influenced research probability•Knowledge gaps are greater in uplands than in wetlands and aquatic habitats•Undersampled areas overlap predicted hotspots of climate change and deforestation
Carvalho et al. map the locations and drivers of ecological research across the Brazilian Amazon. Research facilities and accessibility were strong predictors of research location. Areas with the lowest probability (<0.1%) of research covered about 27.3%, 17.3%, and 54.1% of aquatic, wetland, and upland habitats, respectively.
Interleukin 7 (IL-7) and its receptor, formed by IL-7Rα (encoded by IL7R) and γc, are essential for normal T-cell development and homeostasis. Here we show that IL7R is an oncogene mutated in T-cell ...acute lymphoblastic leukemia (T-ALL). We find that 9% of individuals with T-ALL have somatic gain-of-function IL7R exon 6 mutations. In most cases, these IL7R mutations introduce an unpaired cysteine in the extracellular juxtamembrane-transmembrane region and promote de novo formation of intermolecular disulfide bonds between mutant IL-7Rα subunits, thereby driving constitutive signaling via JAK1 and independently of IL-7, γc or JAK3. IL7R mutations induce a gene expression profile partially resembling that provoked by IL-7 and are enriched in the T-ALL subgroup comprising TLX3 rearranged and HOXA deregulated cases. Notably, IL7R mutations promote cell transformation and tumor formation. Overall, our findings indicate that IL7R mutational activation is involved in human T-cell leukemogenesis, paving the way for therapeutic targeting of IL-7R-mediated signaling in T-ALL.
Summary
A negative relationship between stand biomass and the density of stems is expected to develop during the self‐thinning process in resource‐limited forests; this leads to a large proportion of ...the total biomass occurring in large trees. Nevertheless, frequent disturbance regimes can reduce self‐thinning and the accumulation of large trees.
We investigated size–density relationships and the contribution of large trees (dbh ≥ 70 cm) to stand biomass in 55 1‐ha plots along a 600 km transect in central‐southern Amazonia. The effects of natural‐disturbance gradients (frequency of storms and soil characteristics) and seasonality on forest‐structure components (density of stems and mean individual mass) and stand biomass were examined.
Contrary to self‐thinning predictions, stand biomass increased in forests with higher stem densities. Large trees contained only an average of 5% of stand biomass, and half of the stand biomass was represented by small trees with diameters < 27 cm. These findings indicate that persistent or strong disturbance plays a critical role in forest structure and biomass in the central‐southern Amazon. Frequent storms were identified as an important source of disturbance in the region. Forests under higher frequency of storms had trees with lower individual mass and higher stem packing. More physically restrictive soils seem to magnify the effects of exogenous disturbances limiting individual tree size.
Forests in areas with longer dry seasons had lower stem densities; however, individual mass was higher in these areas. These structural components of biomass seem to counterbalance each other in generating total stand biomass. Seasonality affected forest structural components but not stand biomass.
Synthesis. Forests of central‐southern Amazonia are not resource limited and accumulate most part of their biomass in small‐ to mid‐sized trees. The effects of environmental gradients on specific structural components of stand biomass differ such that strong positive effects on one component can mitigate strong negative effects on other component. Future work on the determinants of stand biomass should investigate forest structure and the contributions of individual components to stand biomass.
Forests of central‐southern Amazonia are not resource limited and accumulate most part of their biomass in small‐ to mid‐sized trees. Disturbance gradients given by the frequency of storms and soil conditions and seasonality were investigated as possible underlying factors influencing this pattern and the variations in stem density, mean individual mass and ultimately above‐ground woody biomass in these forests.
1. A negative relationship between stand biomass and the density of stems is expected to develop daring the self-thinning process in resource-limited forests; this leads to a large proportion of the ...total biomass occurring in large trees. Nevertheless, frequent disturbance regimes can reduce self-thinning and the accumulation of large trees. 2. We investigated size–density relationships and the contribution of large trees (dbh ≥ 70 cm) to stand biomass in 55 1-ha plots along a 600 km transect in central-southern Amazonia. The effects of natural-disturbance gradients (frequency of storms and soil characteristics) and seasonality on forest-structure components (density of stems and mean individual mass) and stand biomass were examined. 3. Contrary to self-thinning predictions, stand biomass increased in forests with higher stem densities. Large trees contained only an average of 5% of stand biomass, and half of the stand biomass was represented by small trees with diameters < 27 cm. These findings indicate that persistent or strong disturbance plays a critical role in forest stmcture and biomass in the central-southern Amazon. Frequent storms were identified as an important source of disturbance in the region. Forests under higher frequency of storms had trees with lower individual mass and higher stem packing. More physically restrictive soils seem to magnify the effects of exogenous disturbances limiting individual tree size. 4. Forests in areas with longer dry seasons had lower stem densities; however, individual mass was higher in these areas. These structural components of biomass seem to counterbalance each other in generating total stand biomass. Seasonality affected forest structural components but not stand biomass. 5. Synthesis. Forests of central-southern Amazonia are not resource limited and accumulate most part of their biomass in small- to mid-sized trees. The effects of environmental gradients on specific structural components of stand biomass differ such that strong positive effects on one component can mitigate strong negative effects on other component. Future work on the determinants of stand biomass should investigate forest structure and the contributions of individual components to stand biomass.
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