Lionel HernándezUniversidad Nacional Experimental de Guayana, UNEG · Centro de Investigaciones Ecológicas de Guayana
Lionel Hernández
Doctor in Forestry
About
89
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Introduction
Lionel Hernández currently works at the Centro de Investigaciones Ecológicas de Guayana, Universidad Nacional Experimental de Guayana, UNEG. Lionel does research in forest Ecology.
Additional affiliations
January 2012 - present
Universidad Nacional Experimental de Guayana, UNEG
Publications
Publications (89)
In a time of rapid global change, the question of what determines patterns in species abundance distribution remains a priority for understanding the complex dynamics of ecosystems. The constrained maximization of information entropy provides a framework for the understanding of such complex systems dynamics by a quantitative analysis of important...
To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser‐availabil...
Relato cronológico de las expediciones al Roraima-tepui desde la época colonial al presente
Otto Huber destaca por sus numerosas publicaciones de estudios sobre flora, vegetación, fitogeografía, ecología y conservación realizados principalmente en Venezuela. Es probable que él sea uno de los científicos naturales más célebres del escudo de Guayana y el que ha generado el mayor número de publicaciones científicas sobre la Guayana venezolan...
Tropical forests are the most diverse and productive ecosystems on Earth. While better understanding of these forests is critical for our collective future, until quite recently efforts to measure and monitor them have been largely disconnected. Networking is essential to discover the answers to questions that transcend borders and the horizons of...
In a time of rapid global change, the question of what determines patterns in species abundance distribution remains a priority for understanding the complex dynamics of ecosystems. The constrained maximization of information entropy provides a framework for the understanding of such complex systems dynamics by a quantitative analysis of important...
American natives have exploited gold, in an artisan way, since before the arrival of
the Spaniards. But recently, some Venezuelan indigenous abandoned the traditional
way of life and began to practice destructive commercial mining; they devastate
forests and soils and use mercury to trap gold. The Orinoco Mining Arc has been the
subject of a great...
Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such “monodominant” forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tr...
Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tr...
Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tr...
The territorial zoning system of Venezuela is based on a diverse set of categories called “Areas under Special
Administration Regime” (ABRAE), which include protected areas. We discuss first how the Venezuelan government
has requested to add a group of ABRAE as protected areas to the World Database on Protected Areas (WDPA), even
though the main ob...
Using data from 50 long-term permanent plots from across Venezuelan forests in northern South America, we explored large-scale patterns of stem turnover, aboveground biomass (AGB) and woody productivity (AGWP), and the relationships between them and with potential climatic drivers. We used principal component analysis coupled with generalized least...
Pair-wise thau (τ) correlation between climate, dynamic and structure variables.
Green colored cells highlight positive correlations > 0.5. Orange cells are negative correlations < -0.5. Gray cells are positive correlations between 0.2 and 0.5. Blue cells are negative correlations between -0.2 and -0.5.
(DOCX)
Parameters of a series of Generalized Least Squares (GLS) models for turnover, aboveground biomass (AGB) and aboveground woody productivity (AGWP) among 50 forest plots in six different regions in Venezuela.
Models were fitted upon prior information and region was added as an additional factor with interactions as appropriate (+ symbol). All models...
General description of permanent plots.
a Climatic Water Deficit (CWD) as in Chave et al. 2014 was obtained from a global climate layer for the long-term average of CWD at 2.5 arc-minute resolution. See: http://chave.ups-tlse.fr/pantropical_allometry.htm. It is measured as the difference between rainfall and evapotranspiration during dry months onl...
Relationships between turnover rates and aboveground biomass (A-C), and aboveground woody productivity (D-F). Red line indicates the mean of each turnover rate. Shaded line is the confidence interval of the linear fit between pairs of variables.
(TIFF)
Estimates of turnover rates, aboveground biomass and productivity for all plots.
(DOCX)
Bioclimatic description of 50 plots in Venezuelan forests.
(TIFF)
A) Kendall’s tau correlation matrix for 10 environmental variables used in the principal component analysis; B) Inertia plot of PCA; C) Relationships between three major axes of variation by region.
(DOCX)
Boxplots of turnover rates (A-B), AGB (C-D), and AGWP (E-F) by three seasonality conditions, and two major soil fertility groups. Letters indicate results from pos-hoc tests when significant differences were found: Turnover and seasonality: F = 4.669, p = 0.014*; Turnover and fertility: F = 13.19, p = 0.000682 ***; AGB and seasonality: F = 6.774, p...
Relationships between the predicted and estimated values of turnover rates (A-B), AGB (C-D), and AGWP (E-F) based on the “best” regression models selected. Left panel refers to climatic models, while the right panel shows structure-based models for each response variable. Correlation values here are based on simple linear models between predicted a...
Species distribution models (SDMs) are widely used in ecology and conservation. Presence-only SDMs such as MaxEnt frequently use natural history collections (NHCs) as occurrence data, given their huge numbers and accessibility. NHCs are often spatially biased which may generate inaccuracies in SDMs. Here, we test how the distribution of NHCs and Ma...
Belongs to paper Species Distribution Modelling: Contrasting presence-only models with plot abundance data by Gomes et al.
Comparing the results of modelling the area of occupancy with MaxEnt and with inverse distance weighting (IDW).
Analysis results for the predicted area of occupancy as calculated by Maxent and IDW methods. The analyses were conducted for 170 of all 227 hyperdominant species that had MaxEnt’s predicted environmental suitability significantly differ...
Species distribution models (SDMs) are widely used in ecology and conservation. Presence-only SDMs such as MaxEnt frequently use natural history collections (NHCs) as occurrence data, given their huge numbers and accessibility. NHCs are often spatially biased which may generate inaccuracies in SDMs. Here, we test how the distribution of NHCs and Ma...
Species distribution models (SDMs) are widely used in ecology and conservation. Presence-only SDMs such as MaxEnt frequently use natural history collections (NHCs) as occurrence data, given their huge numbers and accessibility. NHCs are often spatially biased which may generate inaccuracies in SDMs. Here, we test how the distribution of NHCs and Ma...
The relationship between growth rates and functional traits of 14 species was analyzed using growth modeling of diameter and height, (based on growth ring analysis measurements) and functional traits (wood density, maximum size and maximum age, crown illumination, seed weight of seed and natural regeneration). Through cluster analysis and ecologica...
The Open Letter to IUFRO was handed on Thursday 21st to IUFRO Secretary Authorities. This meeting took place in Freiburg, Germany, in the frame of the 125 Years of IUFRO Anniversary Congress. It was a very positive meeting and the IUFRO Secretary Authorities were very welcoming and are aware of the Venezuelan crisis. They also indicated that IUFRO...
Past human influences on Amazonian forest
The marks of prehistoric human societies on tropical forests can still be detected today. Levis et al. performed a basin-wide comparison of plant distributions, archaeological sites, and environmental data. Plants domesticated by pre-Columbian peoples are much more likely to be dominant in Amazonian forests...
The extent to which pre-Columbian societies altered Amazonian landscapes is hotly debated. We performed a basin-wide analysis of pre-Columbian impacts on Amazonian forests by overlaying known archaeological sites in Amazonia with the distributions and abundances of 85 woody species domesticated by pre-Columbian peoples. Domesticated species are fiv...
The PREDICTS project—Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)—has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used t...
The PREDICTS project—Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)—has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used t...
The PREDICTS project—Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)—has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used t...
Biodiversity conservation requires maintaining an updated knowledge of the species. Therefore, we developed an updated check-list of woody plant species in Machalilla National Park, using three complementary data sources: i) publications and reports, ii) herbarium specimens, and iii) and botanical databases. A total of 579 morpho-species, belonging...
El conocimiento actualizado sobre las especies presentes es
un requisito necesario para lograr el objetivo de conservación de
la biodiversidad en un área protegida como el Parque Nacional
Machalilla. Tanto el inventario como el monitoreo de la biodiversidad
son considerados aspectos claves para alcanzar los objetivos de
conservación de plantas est...
El conocimiento actualizado sobre las especies presentes es
un requisito necesario para lograr el objetivo de conservación de
la biodiversidad en un área protegida como el Parque Nacional
Machalilla. Tanto el inventario como el monitoreo de la biodiversidad
son considerados aspectos claves para alcanzar los objetivos
de conservación de plantas esta...
RESUMEN En un bosque nublado fueron registrados el diámetro, la superficie y la ilumi-nación de copa de 33 árboles correspondientes a 11 especies arbóreas. Durante 26 me ses el diámetro de los árboles fue medido mensualmente con dendrómetros y durante 12 meses fue documentada la fenología. La humedad del suelo, temperatura atmosférica y temperatura...
Estimates of extinction risk for Amazonian plant and animal species are rare, and not often incorporated into land-use policy and conservation planning. Here we overlay spatial distribution models with historical and projected deforestation to show that at least 40% and up to 64% of all Amazonian tree species are likely to qualify as globally threa...
Estimates of extinction risk for Amazonian plant and animal species are rare and not often incorporated into land-use policy and conservation planning. We overlay spatial distribution models with historical and projected deforestation to show that at least 36% and up to 57% of all Amazonian tree species are likely to qualify as globally threatened...
Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species’ threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeograph...
The vast extent of the Amazon Basin has historically restricted the study of its tree communities to the local and regional scales. Here, we provide empirical data on the commonness, rarity, and richness of lowland tree species across the entire Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types. Extra...
The vast extent of the Amazon Basin has historically restricted the study of its tree communities to the local and regional
scales. Here, we provide empirical data on the commonness, rarity, and richness of lowland tree species across the entire
Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types. Extra...
La predominancia de un mosaico de los biomas sabana y bosque en los espacios del sector oriental del Parque Nacional Canaima – PNC en Venezuela, conocido como La Gran Sabana ha sido reportada por numerosos autores. Ellos coinciden en que el fuego ha constituido el factor determinante en la regulación de la superficie de estos dos biomas. Además, la...
In the north of the Gran Sabana, Venezuela, the forest spatial
structure was quantified and the structure and composition
of tree communities was characterized in continuous and
fragmented forests, in terms of fragment size and distance to
forest edge. The results indicate that: 1) the current process of
fragmentation of the forest is at an advance...
In the north of the Gran Sabana, Venezuela, the forest spatial structure was quantified and the structure and composition of tree communities was characterized in continuous and fragmented forests, in terms of fragment size and distance to forest edge. The results indicate that: 1) the current process of fragmentation of the forest is at an advance...
One theory used to explain the high tree species richness in tropical forests involves niche partitioning, whereby species specialize according to the availability of environmental resources in microhabitats. We examined whether there were differences in microhabitats that could account for the composition and diversity of tree regeneration in natu...
There have been several ecological studies in forests of the Guayana Shield, but so far none had examined the changes in structure and composition of evergreen forests with altitude. This study describes and analyzes the structure, species composition and soil characteristics of forest stands at different altitudinal zones in Southeastern Venezuela...
This case study describes the structure of gaps in a montane
forest in Sierra de Lema, Bolivar State, Venezuela. The sizes of
the gaps were measured in the forest canopy (canopy gaps) and
at ground level (extended gaps), and the corresponding microhabitats
assessed. The trees involved in the formation of gaps
were recorded, and their basal areas an...
This case study describes the structure of gaps in a montane forest in Sierra de Lema, Bolivar State, Venezuela. The sizes of the gaps were measured in the forest canopy (canopy gaps) and at ground level (extended gaps), and the corresponding microhabitats assessed. The trees involved in the formation of gaps were recorded, and their basal areas an...
There have been many studies involving the use of hemispherical
photographs to indirectly estimate canopy structures
and forest light environments. A variety of commercial
and free software packages are available for the analysis of
hemispherical photographs. The costs of investment might
represent an advantage of the free programmes over the
comme...
Many evidences suggest that the climate change will deeply
affect tropical forests. Through a review, this paper analyzes the
consequences of climate change on the Neotropical forests and their
perspective. It is not possible to predict exactly, which changes will
happen in the neotropical forests as result of the climate change.
For these ecosyste...
In order to describe and analyze the tree diameter growth in forests along an altitudinal gradient (290-1395masl) in the region of La Escalera, successive tree surveys were undertaken in 22 plots of 0.1ha located at 6 sites during variable monitoring periods from 1 to 5 years. This gradient is located in La Escalera, in the Sierra de Lema, Southeas...
A dendrochronological analysis was carried out for three species of Tachigali and two
of Terminalia to estimate radial growth. In the evergreen forest, Tachigali sp. 1 grew 5,48 ±
2,74 mm/year and Terminalia cf. amazonia 3,23 ± 0,63 mm/year. The wood density rate of
the first species was low (0,432 ± 0,04 g/cm3), and the second high (0,708 ± 0,05 g...
Con el fin de describir y analizar el crecimiento diamétrico arbóreo de bosques en un gradiente altitudinal (290-1395msnm), fueron realizados censos arbóreos sucesivos en 22 parcelas permanentes de 0,1ha localizadas en 6 sitios durante períodos variables de monitoreo de 1 a 5 años. Este gradiente está ubicado en La Escalera en la Sierra de Lema, al...
El compendio que presentamos tiene por objetivo principal servir de instrumento didáctico introductorio en el área de la ecología y el manejo de los bosques húmedos tropicales, poniendo enfasis especial en sus características biofísicas, procesos ecológicos y el uso de sus recursos por parte del hombre. Ciertamente, cumplir tal cometido no es una t...
Canopy dieback in patches was discovered in an otherwise undisturbed very humid lower montane forest on a quartzitic sandstone plateau of the middle Caron river basin, Venezuela. The patches vary in size from about 0.1 to 2 ha (50 to 700 upper story dead trees per ha). Preliminary inventories were carried out at 3 selected sites comparing 4 dieback...
