Neotropical Forests Research Articles

Liana abundance and diversity increase along a successional gradient, even with homogeneous closed canopy

One-half of the pantropical forests are regrowth that develop in certain stages along the succession gradient. As lianas can colonize rapidly in disturbed areas, they play a key role in forest succession and carbon sequestration. However, current knowledge remains limited and is from only a few sites in neotropical forests. Here we investigated liana succession in a chronosequence located in a Southeast Asian Forest. We determined liana abundance (stem density, basal area, prevalence) and diversity along the succession gradient with ages in the range 3–100 years. We also analyzed community composition, size structure, and the correlation with host tree size. We found that liana abundance and diversity increased non-linearly along the succession gradient, suggesting that the stem exclusion stage (35–41 years)—homogeneous closed canopy with low light penetration—did not inhibit liana colonization. Assuming the reverse J-shaped distribution, we fitted the size structure of each plot with the exponential distribution. The results demonstrated no differences among the fitted parameters of plots in the stem exclusion and the old-growth stage, suggesting the same capability of recruitment and colonization in both stages. Furthermore, we found a weak correlation between liana and host tree size (R2 ≤ 0.16, which varied among plots, implying that many lianas recruited after the establishment of large host trees in the past. The results regarding community composition perhaps suggested a stochastic process of liana colonization during the early stage (3–20 years) because of high spatial heterogeneity (a mosaic of open area alternating with closed canopy). In the stem exclusion and old-growth stages, we observed a predictable trajectory, with the composition of plots in the same stage being clustered. This implied that forest structure or unpredictable treefall gaps of old-growth forests have a limited impact on community dissimilarity. Collectively, these results suggested that (1) some liana species may be generalists or even shade-tolerant species, or (2) there was no seed dispersal limitation in the landscape. The contrary direction of the succession patterns reported here suggests a need for more studies across tropical forests including investigating life history trade-offs such as light tolerance.

Stratification and recovery time jointly shape ant functional reassembly in a neotropical forest.

Microhabitat differentiation of species communities such as vertical stratification in tropical forests contributes to species coexistence and thus biodiversity. However, little is known about how the extent of stratification changes during forest recovery and influences community reassembly. Environmental filtering determines community reassembly in time (succession) and in space (stratification), hence functional and phylogenetic composition of species communities are highly dynamic. It is poorly understood if and how these two concurrent filters-forest recovery and stratification-interact. In a tropical forest chronosequence in Ecuador spanning 34 years of natural recovery, we investigated the recovery trajectory of ant communities in three overlapping strata (ground, leaf litter, lower tree trunk) by quantifying 13 traits, as well as the functional and phylogenetic diversity of the ants. We expected that functional and phylogenetic diversity would increase with recovery time and that each ant community within each stratum would show a distinct functional reassembly. We predicted that traits related to ant diet would show divergent trajectories reflecting an increase in niche differentiation with recovery time. On the other hand, traits related to the abiotic environment were predicted to show convergent trajectories due to a more similar microclimate across strata with increasing recovery age. Most of the functional traits and the phylogenetic diversity of the ants were clearly stratified, confirming previous findings. However, neither functional nor phylogenetic diversity increased with recovery time. Community-weighted trait means had complex relationships to recovery time and the majority were shaped by a statistical interaction between recovery time and stratum, confirming our expectations. However, most trait trajectories converged among strata with increasing recovery time regardless of whether they were related to ant diet or environmental conditions. We confirm the hypothesized interaction among environmental filters during the functional reassembly in tropical forests. Communities in individual strata respond differently to recovery, and possible filter mechanisms likely arise from both abiotic (e.g. microclimate) and biotic (e.g. diet) conditions. Since vertical stratification is prevalent across animal and plant taxa, our results highlight the importance of stratum-specific analysis in dynamic ecosystems and may generalize beyond ants.

Anatomical characterization of the vegetative organs of three Solanum sp. L. Juss. (Solanaceae) species popularly known as medicinal

Neotropical forests have many plant species of great value, be it nutritional, ornamental and, mainly, medicinal. The substances present in these species are the most varied and many families are very relevant in this regard. The family Solanaceae comprises many species whose secondary metabolites, including alkaloids, make them an interesting pharmacological target. However, the large number of species in the family and their often, which are often morphologically similar, makes their therapeutic use unsafe. Thus, this study aimed to contribute to the anatomical characterization of the family to assist in the correct identification of species so as to support their safe therapeutic use. The analyzed species (S. paniculatum, S. sisymbriifolium and S. americanum) were collected in Atlantic forest environments and anatomical analyses were performed according to usual protocols in plant anatomy. The results confirmed important diagnostic characteristics for the distinction of the species and provided data that contribute to their safer and more effective use, since their anatomical characterization can be used as a reference to assist in the identification of species.

Prey resources are equally important as climatic conditions for predicting the distribution of a broad‐ranged apex predator

AbstractAimA current biogeographic paradigm states that climate regulates species distributions at continental scales and that biotic interactions are undetectable at coarse‐grain extents. However, advances in spatial modelling show that incorporating food resource distributions are important for improving model predictions at large distribution scales. This is particularly relevant to understand the factors limiting the distribution of widespread apex predators whose diets are likely to vary across their range.LocationNeotropical Central and South America.MethodsThe harpy eagle (Harpia harpyja) is a large raptor, whose diet is largely comprised of arboreal mammals, all with broad distributions across Neotropical lowland forest. Here, we used a hierarchical modelling approach to determine the relative importance of abiotic factors and prey resource distribution on harpy eagle range limits. Our hierarchical approach consisted of the following modelling sequence of explanatory variables: (a) abiotic covariates, (b) prey resource distributions predicted by an equivalent modelling for each prey, (c) the combination of (a) and (b), and (d) as in (c) but with prey resources considered as a single prediction equivalent to prey species richness.ResultsIncorporating prey distributions improved model predictions but using solely biotic covariates still resulted in a high‐performing model. In the Abiotic model, Climatic Moisture Index (CMI) was the most important predictor, contributing 76% to model prediction. Three‐toed sloth (Bradypus spp.) was the most important prey resource, contributing 64% in a combined Abiotic‐Biotic model, followed by CMI contributing 30%. Harpy eagle distribution had high environmental overlap across all individual prey distributions, with highest coincidence through Central America, eastern Colombia, and across the Guiana Shield into northern Amazonia.Main ConclusionsWith strong reliance on prey distributions across its range, harpy eagle conservation programmes must therefore consider its most important food resources as a key element in the protection of this threatened raptor.

The functional importance of rare and dominant species in a Neotropical forest bird community

Bird communities in Tropical forests have high rate of rare species, but only recently some studies suggested their disproportional role for the overall functional diversity. We investigated data from bird communities monitored annually using point counts over ten years in Iguassu National Park, that is a large and protected area in the southern portion of the Atlantic Forest in Brazil. We aimed (1) to determine the rare and dominant species in the community based on their abundance over time; (2) to evaluate the impact of each class of rarity on the overall functional volume of the community; (3) to investigate the pattern of occupancy of the trait space filled by each dominance class, and (4) to assess the disparity in functional trait composition between classes of rarity. We defined dominant, intermediate, and rare species in communities using cluster analysis and data of relative abundance of species in five sections of 1-km in the forest interior. The number of clusters was defined in accordance with the silhouette criterion measures of cohesion and separation that range from −1 to 1, with values > 0.5 indicating high-quality clusters. Among total 138 bird species recorded, 107 were rare, 26 intermediates, and 5 dominants. Our data corroborate a functional disproportional importance of rare bird species in the community considering the functional space (FRic), but functional dispersion (FDis) was not significantly different between the rare and intermediate species. In fact, there is a large overlap of the functional volume occupied by rare in relation to dominant/intermediate species. The niche space occupied by rare species covers most of the space occupied by intermediate and dominant species. The low representativeness of functional turnover indicates that few functions are unique to the classes of higher dominance. Our data suggest the importance of rare bird species to the overall functional diversity but also highlights the potential use of dominants/intermediates species as indicators to select important forests areas for conservation, as certain forest fragments. Through these most abundant species it would be possible to assess which functions are heaviest in abundance, becoming core functions, in the context of each independent forest fragment.

Influence of tree-fall gaps on directional seed dispersal by small mammals in Central Panama

Small mammals, particularly rodents, are often important seed-dispersal agents in Neotropical forests. Directional seed dispersal into tree-fall gaps may enhance seedling survival of light-demanding species and thus influence forest regeneration. To examine this proposition, we tracked seeds of a light-demanding palm (Attalea butyracea), with a focus on spiny rats (Proechimys semispinosus), the most-likely seed-removal agents. We established seed-removal stations at three distances relative to 28 gaps (gap center, gap edge, and intact forest 10 m from a gap edge) in a lowland forest in Central Panama. We placed five fresh fruits (with their seed) in semi-permeable exclosures to exclude larger mammals at each station and tracked the directions in which seeds were moved and deposited intact. More seeds were moved toward or into gaps when removed from gap center or edge stations; however, seeds dispersed from intact forest stations showed no such directionality. Small mammals may have dispersed seeds into and within tree-fall gaps because they favored caching seeds in areas that offered increased cover, which is typical of gaps, and consequently protection from predation. The lack of directional dispersal from intact forest stations may have been because spiny rats were able to find sufficient cover in the young intact forest that was closer than the gaps. In older forest, the contrast between intact forest and gaps may be greater, resulting in directed dispersal into gaps.

First evidence of a monodominant (Englerodendron, Amherstieae, Detarioideae, Leguminosae) tropical moist forest from the early Miocene (21.73 Ma) of Ethiopia.

Many tropical wet forests are species-rich and have relatively even species frequency distributions. But, dominance by a single canopy species can also occur in tropical wet climates and can remain stable for centuries. These are uncommon globally, with the African wet tropics supporting more such communities than the Neotropics or Southeast Asia. Differences in regional evolutionary histories are implied by biogeography: most of Africa's monodominance-forming species are Amherstieae-tribe legumes; monodominance in Neotropical forests occur among diverse taxonomic groups, often legumes, but rarely Amherstieae, and monodominance in Southeast Asian forests occurs mostly among Dipterocarpaceae species. African monodominant forests have been characterized ecologically and taxonomically, but their deep-time history is unknown despite their significant presence and bottom-up ecological influence on diversity. Herein we describe fossil leaflets of Englerodendron mulugetanum sp. nov., an extinct species of the extant genus Englerodendron (Berlinia Clade, Amherstieae, Detarioideae) from the 21.73 Ma Mush Valley site in Ethiopia. We also document a detailed study of associated legume pollen, which originate from a single taxon sharing characters with more than one extant descendant. Taxonomically, the pollen is most comparable to that from some extant Englerodendron species and supports a likely affiliation with the Englerodendron macrofossils. The Mush Valley site provides the first fossil evidence of a monodominant tropical forest in Africa as represented by leaflets and pollen. Previous studies documented >2400 leaves and leaflets from localities at six stratigraphic levels spanning 50,000-60,000 years of nearly continuous deposition within seven meters of section; all but the basal level contain ≥ 50% E. mulugetanum leaflets. Modern leaf litter studies in African mixed vs. monodominant forests indicates the likelihood of monodominance in the forests that surrounded the Mush paleolake, particularly after the basal level. Thus, we provide an early case for monodominance within the Amherstieae legumes in Africa.

Mineralogical control on physically protected soil organic matter in a neotropical moist forest

Context Minerals and organic matter physically associate in many soils, yet the precise nature, either via a hierarchy of aggregate particles or by build-up of organo–mineral associations, remains obscure, especially in tropical forest environments. Aims We investigated physically protected organic matter by comparing soils with contrasting parent material, topography, and pedogenesis, but with similar tropical moist forest on Barro Colorado Island in the lowlands of Panama. Methods Bulk soil from 10 sites was separated by size into free-floating particles, macroaggregates (>250 μm), microaggregates (53–250 μm), and <53-μm particles. A subsample of macroaggregates was disintegrated and separated into coarse particles (>250 μm), occluded microaggregates, and occluded <53-μm particles. Concentrations and natural abundance of stable isotopes for carbon (C) and nitrogen (N) were determined for each fraction, and ratios (C:N, stable isotopes) were used to characterise organic matter for each fraction. Key results Macroaggregates were the largest fraction of bulk soil (71%) and were 15% greater in kaolinite- than smectite-dominated soils. Macroaggregates were composed of coarse particles (14%), occluded microaggregates (62%), and occluded <53-μm particles (24%). Concentrations of C and N widely varied among fractions but the variation was not related to clay mineralogy. The C:N ratio and stable N isotope ratio indicated more decomposed organic matter in kaolinite- than smectite-dominated soils. Conclusions and implications Macroaggregates composed of plant detritus and microaggregates in the Barro Colorado Island soils imply that the aggregate hierarchy route ultimately protects soil organic matter in this tropical forest environment.

El Niño oscillations impact anti-predator defences to alter survival of an herbivorous beetle in a neotropical wet forest

Abstract Little is known about the effects of El Niño-Southern Oscillation (ENSO) on tropical insect communities, even though they are suffering rapid declines in complexity and stability due to climate change. We explore the impact of fluctuations in local climate imposed by ENSO on the performance of herbivore defences mediating enemy interactions. In a widespread rainforest edge community, we quantified the mortality caused by five enemy guilds on the immature stages of the herbivorous beetle, Acromis sparsa. ENSO was a significant determinant of beetle mortality. During warmer, drier El Niño years, the survival of beetles decreased. This was due to increased egg parasitism by wasps, which reduced hatching. Additionally, ant predation on beetle larvae increased. Flies and wasps were in competition for larval prey in wetter, cooler La Niña years. Experimental removal of maternal guards or chemical shields revealed which ENSO-related parameters predicted larval mortality. Guarding was most effective against social wasps in La Niña, whereas shields proved most effective in El Niño. Two ENSO-related defence–enemy breakdowns occurred: (1) decoupling whereby the efficacy of a narrow defensive adaptation was reduced to increase mortality, and (2) mismatching whereby the resistance of a narrow defensive adaptation against non-targeted enemies was further reduced to increase mortality. These results highlight that defence efficacy against natural enemies can vary predictably with biotic and abiotic environmental conditions. ENSO events will increase breakdowns in defence-mediated interactions, shifts in competition among enemies, and species loss.

Germination niche of a neotropical dry forest species: seed osmotic stress and recovery

Abstract: Erythrina velutina Willd is a native Fabaceae with wide occurrence, mainly in the Caatinga Domain with multiple uses. This study aimed to compare the vulnerability/tolerance of seeds of four accessions of E. velutina to osmotic stresses. Four replications were conducted with 25 seeds, germinated in osmotic solutions of NaCl or PEG up to -1.73 MPa. Seeds that did not germinate after 14 days were recovered in distilled water. Obtained data were fitted in Boltzmann curves and t50 and synchrony were evaluated. A probit analysis was performed, and hydrotime and halotime models were constructed. In distilled water, the germination curve was similar for all accessions. When the concentration of salt or PEG in the substrate increased, the accessions differentiated into two groups. Two accessions - Jutaí 2012 and Jutaí 2015 - maintained high germination up to -0.86 MPa NaCl, while Caboclo 2008 and Caiçara 2011 accessions presented a lower germination speed. The hydrotime and halotime analyses separated the germination response of accessions according to their physiological quality and tolerance to osmotic and saline conditions. Seeds viability was maintained at both stresses, since germination was reestablished at distilled water, thus constituting a crucial response for this species’ survival and conservation.

Phylogenetic diversity and structure in moist and dry upland forests in the semi-arid region of Brazil.

Understanding the factors influencing variation in the diversity and structure of rich biological communities (e.g., Neotropical upland forests) is essential in the context of climate change. In this study, we examine how environmental filters (temperature, precipitation, and elevation) and distinct habitats (moist upland forests - MUF and dry upland forests - DHF) influence the phylogenetic diversity and structure of 54 tree communities (28 MHF and 26 DHF). We used the standardized effect size (ses) of the metrics phylogenetic diversity (ses.PD), mean pairwise distance (ses.MPD), and mean nearest neighbor distance (ses.MNTD) to quantify changes in tree community diversity and structure. Then, we assessed the relationships of the phylogenetic metrics with the environmental filters as predictors using generalized linear models (GLMs). Our results indicate that increasing temperature negatively affects the phylogenetic indices analyzed, leading to less diverse and more clustered communities. In contrast, increasing precipitation and elevation showed a significant positive relationship with the analyzed indices, directing communities towards greater phylogenetic diversity and random or overdispersed structure. Our findings also reveal that phylogenetic diversity and structure vary with habitat type. For example, while MUFs exhibit higher phylogenetic diversity and random structure, DUFs display lower phylogenetic diversity and clustered structure. In conclusion, our results suggest that the phylogenetic patterns exhibited by upland communities in the semiarid region are strongly related to climatic conditions and the habitat in which they are found. Therefore, if the predicted temperature increases and precipitation decreases in climate change scenarios for the semi-arid region materialize, these communities may face significant biodiversity loss.

Population structure and body condition of White-crested Elaenia (Elaenia albiceps) in relation to habitat in a modified Neotropical forest landscape

Despite the widely accepted view that planted forests are valuable habitat for wildlife species, there is a lack of empirical evidence showing the suitability of this novel habitat, especially in relation to plantations of exotic tree species. Furthermore, little is known about the effects of forest management on the ecology and dynamics of wild populations in the Neotropics. During the breeding season, the migrant flycatcher White-crested Elaenia is the most abundant bird species in forested landscapes in Chile. For several years we have studied different aspects of these artificial forests in the coastal range of south-central Chile as habitat for the species, particularly in contrast to the native forest. In general, our results indicate that plantation forests offer a poorer quality habitat, where the density of the species tends to be lower than in the native forest, although a significant edge effect suggests that its quality can be mitigated by planting as a matrix mosaic with native forest. Furthermore, compared to native forests, populations in plantations contained a higher proportion of younger adult individuals maintaining larger territories, and showing poorer body condition. We suggest that these differences could also have an impact on the birds’ longevity and survival.

Reproductive phenology of timber tree species in the Yungas Piedmont Forest of Argentina

The tree reproductive phenology in the seasonal neotropical forest is driven by many abiotic and biotic factors and provides information to understand the biological processes of ecosystems. The Yungas Piedmont Forest in Argentina is one of the areas with the greatest biodiversity and timber resources in the country. However, limited knowledge of the reproductive phenology of these species has resulted in inadequate management plans and protocols. In this study, we observed the reproductive phenology of eight timber tree species in the Yungas Piedmont Forest over a two-year period and evaluated the relationship between local climatic conditions (temperature, precipitation, and photoperiod) and reproductive phenology. In the Yungas Piedmont forest, the reproductive phenology of timber tree species presented intermediate intensity, and short duration. The reproductive phenology of each species was seasonal and mainly modulated by photoperiod. Concerning the timing of each phenophase, we found interspecific variation in reproductive phenological strategies. Flowering occurred mainly during the late dry season up to early wet season and fruiting had two annual intensity peaks, one per season. This study provides valuable information on the phenological patterns of economically important tree species in the Andean Forest, and it is essential for underpinning conservation and restoration actions in the Yungas forests.

Beyond the “empty forest”: The defaunation syndromes of Neotropical forests in the Anthropocene

Beyond the “empty forest”: The defaunation syndromes of Neotropical forests in the Anthropocene

Predicting co-distribution patterns of parrots and woody plants under global changes: The case of the Lilac-crowned Amazon and Neotropical dry forests

Global climate and land-use changes are the most significant causes of the current habitat loss and biodiversity crisis. Although there is information measuring these global changes, we lack a full understanding of how they impact community assemblies and species interactions across ecosystems. Herein, we assessed the potential distribution of eight key woody plant species associated with the habitat of the endangered Lilac-crowned Amazon (Amazon finschi) under global changes scenarios (2050′s and 2070′s), to answer the following questions: (1) how do predicted climate and land-use changes impact these species’ individual distributions and co-distribution patterns?; and (2) how effective is the existing Protected Area network for safeguarding the parrot species, the plant species, and their biological interactions? Our projections were consistent identifying the species that are most vulnerable to climate change. The distribution ranges of most of the species tended to decrease under future climates. These effects were strongly exacerbated when incorporating land-use changes into models. Even within existing protected areas, >50 % of the species’ remaining distribution and sites with the highest plant richness were predicted to be lost in the future under these combined scenarios. Currently, both individual species ranges and sites of highest richness of plants, shelter a high proportion (ca. 40 %) of the Lilac-crowned Amazon distribution. However, this spatial congruence could be reduced in the future, potentially disrupting the ecological associations among these taxa. We provide novel evidence for decision-makers to enhance conservation efforts to attain the long-term protection of this endangered Mexican endemic parrot and its habitat.

Effect of Deforestation on Land Surface Temperature in the Chiquitania Region, Bolivia

Neotropical forests offer alternatives to surface cooling and their conservation is an effective solution for mitigating the effects of climate change. Little is known about the importance of tropical dry forests for temperature regulation in Chiquitania, a region with increasing deforestation rates. The impact that deforestation processes are having on the surface temperature in Chiquitania remains an open question. This study evaluated trends in forest cover loss based on land surface temperatures (°C) in forested and deforested areas in Chiquitania. We hypothesized a positive relationship between higher deforestation and a temperature increase, which would decrease the resilience of highly disturbed Chiquitano forests. We evaluated ten sampling sites (10 × 10 km), including five in forested areas with some type of protection and the other five in areas with populated centers and accelerated forest loss. We developed scripts on the Google Earth Engine (GEE) platform using information from the Normalized Difference Vegetation Index (NDVI, MOD13A2) and the daytime and nighttime Land Surface Temperature (LST, MYD11A1) from MODIS products for the period 2001–2021. The statistical significance of the trends of the time series averages of the MODIS products was analyzed using a nonparametric Mann–Kendall test and the degree of the relationship between the variables was determined using the Pearson statistic. Our results based on NDVI analysis showed consistent vegetation growth in forested areas across the study period, while the opposite occurred in deforested lands. Regarding surface temperature trends, the results for daytime LST showed a positive increase in the four deforested areas. Comparatively, daytime LST averages in deforested areas were warmer than those in forested areas, with a difference of 3.1 °C. Additionally, correlation analyses showed a significant relationship between low NDVI values due to deforestation in three sites and an increase in daytime LST, while for nighttime LST this phenomenon was registered in two deforested areas. Our results suggest a significant relationship between the loss of forest cover and the increase in land surface temperature in Chiquitania. This study could be the first step in designing and implementing an early climate–forest monitoring system in this region.

Neotropical urban forest allergenicity and ecosystem disservices can affect vulnerable neighborhoods in Bogota, Colombia

Tree allergenicity has been documented as a relevant ecosystem disservice, a tradeoff to the many co-benefits of urban trees. However, information on the allergenic tree dynamics in Neotropical urban environments is scarce. We used species-level Allergenic Potential Value (APV) and pollen-emission capacity as well as data on treestructure and diversity to explore the spatial dynamics of tree allergenicity in Bogota Colombia's public urban forest. We then statistically and spatially analyzed this data along with socioeconomic and vulnerability information to better understand tree allergenicity dynamics and its role as a tropical urban ecosystem disservice. Results show that most of high APV species were present in the lowest socioeconomic strata. Hierarchical cluster analyses indicates that trees with higher APVs trend towards specific sectors in the city. Vulnerable neighborhoods were also identified according to public health access and age-related sociodemographic and used to discuss allergenicity-related ecosystem disservices. Findings show a paucity of tree cover in some vulnerable neighborhoods indicating not only an absence of allergy-related ecosystem disservices, but of overall ecosystem services as well. This approach using information sources can be used to better select functional traits, tree species, and planting strategies to reduce allergy and ecosystem disservice hotpots in tropical urban cities.

Linking disturbances in neotropical landscapes with ecosystem functional traits: A preliminary assessment using epigaeic and leaf‐litter ant communities

Abstract Environmental stressors and changes in land use have led to rapid and dramatic species losses and a reduction in associated ecosystem services. Functional diversity has increasingly been suggested as an alternative for evaluating anthropogenic disturbances and restoration programs because it reflects different aspects of the relationship between biological diversity, ecosystem functioning and environmental constraints. Ants are important components of terrestrial food webs and a key group associated with diverse interactions and ecosystem processes. Additionally, their sensitiveness and rapid response to environmental changes pave the way for their use as informative metrics for monitoring several processes that threaten biodiversity and ecosystem services. Consequently, ants' functional diversity might be considered leading edge indicators to assess ecosystem changes to ongoing anthropogenic disturbances. The purpose of this study was to gauge the usefulness of epigaeic and leaf‐litter ants' functional responses towards measuring ecosystem degradation (and/or restoration) in the Brazilian Amazon. Our results demonstrate that functional traits exhibited sensitivity to ongoing changes, as well as different responses to specific environmental disturbances. Communities supporting ants with specialised functional traits associated with pristine ecosystems suffered high species loss and were correlated with specific anthropogenic stressors. The results obtained pinpoint the importance of pristine ecosystems for conserving unique functional attributes and biodiversity in neotropical forest landscapes. We highlight the significance of further studies in this scope to guide environmental managers and practitioners in applying the best policies for integrated neotropical landscapes conservation, considering the competing interests of farmers, foresters and conservationists, but also the unpredictable effects of local and regional environmental changes.

Assessing the drought effect on tree rings' width and xylem traits plasticity in Symplocos coccinea and S. speciosa: two rare and endemic Neotropical montane oak forest trees from eastern Mexico

Assessing the drought effect on tree rings' width and xylem traits plasticity in Symplocos coccinea and S. speciosa: two rare and endemic Neotropical montane oak forest trees from eastern Mexico

Prediction of Soil Erodibility by Diffuse Reflectance Spectroscopy in a Neotropical Dry Forest Biome

The USLE and the RUSLE are two common erosion prediction models that are used worldwide, and soil erodibility (K-factor) is one parameter used to calculate them. The objectives of this study were to investigate the variability of soil-erodibility factors under different soil-texture classes and evaluate the efficiency of diffuse reflectance spectroscopy (DRS) in the near-infrared range at predicting the USLE and RUSLE K-factors using a partial least squares regression analysis. The study was conducted in Fluvisols in dry tropical forest (the Caatinga). Sampling was undertaken in the first 20 cm of soil at 80 sites distributed 15 m apart on a 70 m × 320 m spatial grid. Results show that the clay fraction is represented mainly by 2:1 phyllosilicates. Soil organic matter content is low (<0.2%), which is typical of tropical dry forests, and this is reflected in the high values of the calculated USLE and RUSLE K-factors. An empirical semivariogram was used to investigate the spatial dependence of both K-factors. Pedometric modeling showed that DRS can be used to predict both USLE (R2adj = 0.53; RMSE = 8.37 10−3 t h MJ−1 mm−1) and RUSLE (R2adj = 0.58; RMSE = 6.78 10−3 t h MJ−1 mm−1) K-factors.