Browsing by Tema "Abundance (ecology)"

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A comparison of bird communities in the anthropogenic and natural-tree fall gaps of a reduced-impact logged subtropical forest in Bolivia
(Cambridge University Press, 2008) Adam Felton; Jeff T. Wood; Annika M. Felton; David B. Lindenmayer; Bennett Hennessey; David B. Lindenmayer; Bennett A. Hennessey
Abstract We studied bird community composition and abundance within four vegetation and disturbance categories located within selectively logged and unlogged forest in a Bolivian subtropical lowland forestry concession. The logged forest was subject to reduced-impact logging between 1 and 4 years prior to our study. The four categories were: 1) ‘gap’ points possessing natural or anthropogenic tree-fall gaps; 2) ‘target’ points with one of five commercial tree species of harvestable size; 3) ‘future’ points possessing a commercial tree below harvestable size and 4) ‘non-target’ points not possessing harvestable tree species. The bird community composition of logging gaps significantly differed from that found within natural tree-fall gaps in the unlogged forest P < 0.05. Species richness was higher in natural tree-fall gaps than in anthropogenic gaps. Furthermore, a higher proportion of disturbance sensitive species were associated with natural-tree fall gaps, whereas a higher proportion of disturbance tolerant species were associated with anthropogenic gaps. No significant difference was detected in the bird community composition for the other three vegetation categories surveyed. We discuss the conservation and silvicultural repercussions of these results.
A metacommunity ecological approach to understanding the community organization of fish in artificial ponds of the Mamoré River floodplain in the Amazonian lowlands of Bolivia
(Springer Science+Business Media, 2018) Takayuki Yunoki; Luis V. Torres; Reinaldo B. Cholima
Abundance of early life stages of the surf silverside <i>Notocheirus hubbsi</i> (Teleostei, Atheriniformes) in the coastal nearshore of central Chile
(University of Valparaíso, 2021) Francisca Zavala‐Muñoz; Mauricio F. Landaeta; Valentina Bernal‐Durán; Claudia A. Bustos; Bryan S. Dyer
The abundance of early stages of the surf silverside Notocheirus hubbsi in nearshore waters of central Chile, collected in samplings set up to assess the lunar cycle during austral spring and summer is reported. A total of 19 specimens were collected with light traps, 16 larvae (7.89-16.20 mm SL) in austral spring and 3 juveniles (30.70-34.60 mm SL) in summer. Capture per unit effort (CPUE) varied from 0.33 to 2.00 ind. light trap-1 night-1 during the entire study period (September 2015-February 2016, and September 2016-February 2017). N. hubbsi catches recorded maximum abundance during the new moon and no catches during full moon.
Abundancia, recursos alimenticios y uso antrópico de los crácidos (Aves: Galliformes) en un bosque amazónico de Bolivia
(2006) Omar Martínez; Jhonny Ayala
ABUNDANCE, FOOD RESOURCES AND HUMAN USE OF CRACIDS (BIRDS: GALLIFORMES) IN AN AMAZONIAN FOREST OF BOLIVIA En noviembre de 1999 y octubre de 2001, mediante transectos lineales se estudio la densidad, preferencia de habitat y uso de recursos alimenticios de cuatro especies de cracidos (Mitu tuberosa, Pipile cumanensis, Penelope jacquacu y Ortalis guttata) y mediante entrevistas, la presion y frecuencia de caza por pobladores de El Curlchon - Lago Bay, provincia Manuripi, Pando (Bolivia). Un total de 78 km fueron recorridos en todos los transectos combinados. La densidad de M. tuberosa vario desde 0.02 hasta 1,77 ind /km 2 , en P. jacquacu de 0,20 a 3,07 ind/km 2 y en O. guttata de 5,84 a 3,22 ind/km 2 , cerca y lejos de la comunidad, respectivamente. P. cumanensis no fue registrada en los transectos. P. jacquacu se asocio a bosques de altura en tierra firme. O. guttata tiene preferencia a ambientes antropogenizados. Se determino 32 especies de plantas potenciales en la dieta de las pavas estudiadas. Moraceae y Arecaceae fueron las mas representativas con 10 (31%) y 7 especies (22%), respectivamente. El numero promedio mensual de individuos consumidos por cazador fue de 12,8 ± 1,9 para P. jacquacu, 6,8 ± 1,8 para M. tuberosa, 2,7 ± 2,3 para P. cumanensis y 10,7 ± 6,6 para O. guttata. El numero promedio anual de viajes al bosque por cazador fue de 44 ± 10,4. Estos resultados sugieren que la presion de caza de cracidos en la region estuvo directamente relacionada a la abundancia mas que al tamano de cada especie. Palabras claves: Recursos alimenticios, uso antroplco, bosque ribereno, bosque alto de tierra firme, Amazonas, Cracidae, aves, Boilvia. ABSTRACT In November 1999 and October 2001 the density, habitat preference, and food resource use of four species of cracids were studied at Lago Bay, Manuripl Provlnce, Pando Department (Bolivia), using Une transects. Based on interviews of settlers of the viilage of El Curichon, the pressure and frequency of huntlng was determined. A total of 78 km were surveyed in all combined transects. Density of cracids varied from 0.02 - 1.77 ind/km 2 in Razor-billed Curassow (Mitu tuberosa), 0.20 - 3.07 ind/km 2 in Spix's Guan (Penelope jacquacu) and 5.84 - 3.22 ind/km 2 in Speckled Chachalaca (Ortalis guttata) near and far from the community, respectively. Blue-throated Piping-Guan (Pipile cumanensis) was not registered on the transects. Spix's Guan was associated with tall “terra firme” forest and Speckled Chachalaca with anthropogenically dlsturbed habitats. Thlrty two species of potential food plants for cracids were identified. Moraceae and Arecaceae were the most representative families with 10 (31 %) and 7 species (22%), respectively. The monthly mean number of individuais consumed per hunter was 12.8 ± 1.9 for Spix's Guan, 6.8 ± 1.8 for Razor-billed Curassow, 2.7 ± 2.3 for Blue-throated Piping-Guan and 10.7 ± 6.6 for Speckled Chachalaca. The annual mean number of trips to the forest per hunter was 44 ± 10.4. These results suggest that the harvest of cracids in the region was related more to the abundance than the slze of each species. Key words: Food resources, human use, riverine forest, “terra firme” forest, Amazon, Cracidae, birds, Bolivia
Amphibian community along elevational and habitat disturbance gradients in the Taita Hills, Kenya
(2011) Patrick K. Malonza; Michael Veith
We evaluated the relationship between amphibian composition along anthropogenic habitat disturbance and elevational gradients in the Taita Hills. We tested the hypotheses that there is a clear amphibian species turnover with elevation, and that human habitat disturbance influence abundance of amphibian reproductive strategies. Transects were used in surveying amphibians. Sampling was done in two broad habitat types (terrestrial forests/plantations, and aquatic streams/dams). We used Kruskal-Wallis to test the differences in amphibian species richness and diversity among the habitat types, while EstimateS program was used to estimate species diversity and abundance. Comparison of species richness was done using Sorensen similarity index with amphibian communities as zoogeographic indicators. Multivariate cluster analysis was used to examine the community similarity in terms of habitat type and elevation. Cluster analysis of community similarity revealed distinct species assemblages in terms of elevation and habitat type. Amphibian species richness increased with increased habitat disturbance from forests to streams and dams but decreased with increasing elevation. However, abundance of species with direct developing mode of reproduction decreased with increased habitat modification/disturbance. These findings clearly demonstrate that conservation investment in protection of the Taita Hills should be directed towards terrestrial indigenous forests which are home to the three area endemics and direct developers (Boulengerula taitana, Boulengerula niedeni and Callulina dawida). We therefore strongly support efforts to protect a network of these indigenous forest fragments with some form of connectivity alongside the human modified habitats. Recognizing the role of ecosystem restoration in protecting biodiversity in fragmented habitats, this study strongly supports restoration efforts involving gradually replacing exotic forest plantations with indigenous plants. Key words: Anurans, Gymnophiona, habitat change, altitude, primary productivity, climate, biogeography, species richness, Africa. Resumen Comunidad de anfibios a lo largo de gradientes altitudinales y de perturbacion de habitat en Taita Hills, Kenia Evaluamos la relacion entre la composicion de anfibios a lo largo de gradientes altitudinales y con perturbacion antropogenica de habitat en Taita Hills. Pusimos a prueba las hipotesis de que hay un claro recambio de especies con la altura, y que la perturbacion humana de habitat influye en la abundancia de estrategias reproductivas en anfibios. Transectas fueron empleadas en el inventario de anfibios. El muestreo fue llevado a cabo en dos tipos de habitats amplios (bosques/plantaciones terrestres, y riachuelos/represas acuaticas). Empleamos Kruskal-Wallis para poner a prueba las diferencias en la riqueza de especies de anfibios y la diversidad entre los tipos de habitat, mientras que el programa EstimateS fue usado para estimar la diversidad y abundancia de especies. La comparacion de riqueza de especies fue realizada usando el indice de similitud de Sorensen con comunidades de anfibios como indicadores zoogeograficos. Analisis cluster multivariado fue empleado para examinar la similitud de comunidad en terminos de tipo de habitat y elevacion. Analisis cluster de similitud de comunidad revelo distintos ensambles de especies en terminos de tipo de habitat y elevacion. La riqueza de especies de anfibios se incremento con perturbacion de habitat incrementada de bosques a riachuelos y represas pero disminuyo con el incremento en elevacion. Sin embargo, la abundancia de especies con modo de reproduccion de desarrollo directo disminuyo con modificacion/perturbacion de habitat incrementada. Estos hallazgos claramente demuestran que la inversion de conservacion en la proteccion de Taita Hills debe ser dirigida hacia bosques terrestres nativos que son hogar de los tres endemismos con desarrollo directo (Boulengerula taitana, Boulengerula niedeni y Callulina dawida). Por consiguiente nosotros apoyamos fuertemente los esfuerzos para proteger una red de estos fragmentos nativos de bosque con alguna forma de conectividad a lo largo de habitats modificados por el hombre. Reconociendo el papel de la restauracion de ecosistemas en la proteccion de biodiversidad en habitats fragmentados, este estudio apoya fuertemente los esfuerzos de restauracion que involucran el reemplazo gradual de plantaciones forestales exoticas con plantas nativas. Palabras clave: Anuros, Gymnophiona, cambio de habitat, elevacion, productividad primaria, clima, biogeografia, riqueza de especies, Africa
Anthropogenic ecosystem disturbance and the recovery debt
(Nature Portfolio, 2017) David Moreno‐Mateos; Edward B. Barbier; Peter C. Jones; Holly P. Jones; James Aronson; José A López-López; Michelle L. McCrackin; Paula Meli; Daniel Montoya; José María Rey Beñayas
Antibiotic resistance genes and class 1 integron: Evidence of fecal pollution as a major driver for their abundance in water and sediments impacted by metal contamination and wastewater in the Andean region of Bolivia
(2020) Jorge Agramont; Sergio Gutiérrez-Cortez; Enrique Joffré; Åsa Sjöling; Carla Calderon Toledo
Abstract Water and sediment samples affected by mining activities were collected from three lakes in Bolivia, the pristine Andean lake Pata Khota, the Milluni Chico lake directly impacted by acid mine drainage, and the Uru-Uru lake located close to Oruro city and highly polluted by mining activities and human wastewater discharges. Physicochemical parameters, including metal compositions, were analyzed in water and sediment samples. Antibiotic resistance genes (ARGs), were screened for, and verified by quantitative PCR together with the mobile element class 1 integron ( intl1 ) as well as crAssphage, a marker of human fecal pollution. The gene intl1 showed a positive correlation with sul1, sul2, tetA and blaOXA-2 . CrAssphage was only detected in Uru-Uru lake and its tributaries and significantly higher abundance of ARGs were found in these sites. Multivariate analysis showed that crAssphage abundance, electrical conductivity and pH were positively correlated with higher levels of intl1 and ARGs. Taken together our results suggest that fecal pollution is the major driver of higher ARGs and intl1 in wastewater and mining contaminated environments.
Apuntes sobre la invasión de Wasmannia auropunctata (Hymenoptera: Formicidae) en tres especies de bromelias de tanque presentes en el Parque Nacional Guanahacabibes, Cuba
(2018) Omar Ernesto Falero Álvarez; Jorge Ferro Díaz; Lázaro Yusnaviel García Padrón
Wasmannia auropunctata is an alien ant whose invasion is considered significant in a wide range of countries, coming to be considered an agricultural pest in countries of the tropical region, reason why it has been reported as one of the five species of ants included in the list of the 100 worst invasive species. Starting from a study that takes place in the semideciduous forest of the area of public use in Guanahacabibes National Park about the relationship between three species of epiphytic bromeliads (Tillandsia fasciculata, T. utriculata and Hohenbergia penduliflora) and their associated fauna, the report is presented for the first time for the territory of the invasion of this exotic species, exposing its relationship with each of the three bromeliads sampled, the effect of the year season (rainy and not very rainy) and the distribution according to the height ranges in the phorophytes (four height ranges) in which the samples of the individuals of the epiphytic bromeliad species were sampled. In the work it is evident that there is no preference for any of the three bromeliads, although in H. penduliflora the abundance is proportional according to the season of the year; it is also detected that the largest distribution is in the range of 2.1 to 4 m in height in the phorophyte.
Are the effects of adjacent habitat type on seagrass gastropod communities being masked by previous focus on habitat dyads?
(CSIRO Publishing, 2015) Quinn Ollivier; Nikki Antonia Bramwell; Edd Hammill; Cian Foster‐Thorpe; David J. Booth
Variation in abundance and diversity of organisms along habitat edges has long been a key research focus in both terrestrial and marine ecosystems. Previous investigations into edge effects in seagrass ecosystems have predominantly focussed on the seagrass–sandy substrate boundary. However, little is known about what role other habitats (e.g. rocky algal reefs) may play in faunal assemblage patterns. This study investigated the strength to which habitat type influenced gastropod assemblages within seagrass (Posidonia australis) beds, bordered by both sandy substrate and rocky algal reef. We found that benthic invertebrate community composition significantly changed with distance from rocky algal reef, but not with distance from sandy substrate. Proximity to rocky reef had a stronger effect on community composition than other local drivers examined (seagrass biomass and sand particle size). We hypothesise that gastropod affinity for rocky algal reef may be a result of both species-specific habitat preference, and lower predation pressure along adjacent rocky algal reef habitats. This study provides evidence that heterogeneous habitats within close proximity to seagrass beds may exert previously overlooked effects on the distribution of gastropod assemblages, highlighting the need for the inclusion of adjacent habitat type in experimental design for gastropod assemblage distribution studies.
Artificial Green Corridors in an Andean City as Effective Support of Avian Diversity
(Multidisciplinary Digital Publishing Institute, 2023) Alain Hambuckers; Johann Delcourt; Bryan Leborgne; Jennifer R. A. Cahill
Ensuring connectivity in the countryside and cities is a key element of nature protection, allowing genetic fluxes between populations in fragmented ecosystems. We tested the hypothesis that artificial green corridors are effective for birds in the city of Cochabamba (Bolivia). We compared the following aspects of natural corridors, with generally preserved vegetation, to those of artificial corridors, constituting parks and gardens in a matrix of streets densely planted with trees: species abundance and richness, functional diversity, and the traits of bird communities. We used canonical redundancy analysis to relate species abundance to the corridor type, noise, tree vegetation structure, richness, and functional diversity. We also tested the explanatory factors for relationships with bird species richness, functional diversity, and traits. We found that most species were shared between the corridor types; the corridor type, nevertheless, had significant effects, with bird species in the green corridors being more common and heavier and having a lower beak depth/mass. By contrast, noise-reflecting urbanization deeply affected all of the studied traits, indicating large shifts in species composition. In conclusion, green corridors seem reliable enough to maintain birds at a level almost comparable to that in linear corridors, but noise is a limiting factor for efficiency for both types.
Assessing Local Knowledge of Game Abundance and Persistence of Hunting Livelihoods in the Bolivian Amazon Using Consensus Analysis
(Springer Science+Business Media, 2010) Tracy Van Holt; Wendy R. Townsend; P. Cronkleton
Assessing the geographic dichotomy hypothesis with cacti in South America
(Wiley, 2017) Ariel A. Arzabe; Luís F. Aguirre; M. P. Baldelomar; Marco A. Molina‐Montenegro
The Cactaceae is one of the most conspicuous and ecologically important plant families in the world. Its species may have specialist or generalist pollination systems that show geographic patterns, which are synthesised in the Geographic Dichotomy Hypothesis. Here, we assess this hypothesis in five countries in both tropical and extratropical regions, evaluating the pollinator visitation rate and pollinator identity and abundance. We calculate the Shannon diversity index (H') and evenness (J) and evaluate differences between latitude parameters with a Student t-test. Overall, we found more specialised pollination systems in all tropical sites; the richness, diversity and evenness of pollinators was reduced in comparison to extratropical regions, where the pollination system was generalised. Our results support the geographic dichotomy hypothesis in the cacti of South America, suggesting that environmental factors underlying the latitudinal patterns can help to explain differences in the pollination syndrome between tropical and extratropical regions.
Bad company expands in highland areas: Overlapping distribution, floral resources and habitat suggest competition between invasive and native bumblebees
(Elsevier BV, 2023) Rodrigo M. Barahona‐Segovia; Cecilia Smith-Ramírez; Vanesa Durán-Sanzana; Juan Carlos Huaranca; Patricio Pliscoff
Bird community responses to different urban conditions in La Paz, Bolivia
(Springer Science+Business Media, 2010) Mariana Villegas; Álvaro Garitano‐Zavala
Bird community responses to reduced-impact logging in a certified forestry concession in lowland Bolivia
(Elsevier BV, 2008) Adam Felton; Jeff T. Wood; Annika M. Felton; Bennett Hennessey; David B. Lindenmayer; Bennett Hennessey; David B. Lindenmayer
Building essential biodiversity variables (<scp>EBV</scp>s) of species distribution and abundance at a global scale
(Wiley, 2017) W. Daniel Kissling; Jorge Ahumada; Anne Bowser; Miguel Fernández; Néstor Fernández; Enrique Alonso García; Robert Guralnick; Nick J. B. Isaac; Steve Kelling; Wouter Los
Much biodiversity data is collected worldwide, but it remains challenging to assemble the scattered knowledge for assessing biodiversity status and trends. The concept of Essential Biodiversity Variables (EBVs) was introduced to structure biodiversity monitoring globally, and to harmonize and standardize biodiversity data from disparate sources to capture a minimum set of critical variables required to study, report and manage biodiversity change. Here, we assess the challenges of a 'Big Data' approach to building global EBV data products across taxa and spatiotemporal scales, focusing on species distribution and abundance. The majority of currently available data on species distributions derives from incidentally reported observations or from surveys where presence-only or presence-absence data are sampled repeatedly with standardized protocols. Most abundance data come from opportunistic population counts or from population time series using standardized protocols (e.g. repeated surveys of the same population from single or multiple sites). Enormous complexity exists in integrating these heterogeneous, multi-source data sets across space, time, taxa and different sampling methods. Integration of such data into global EBV data products requires correcting biases introduced by imperfect detection and varying sampling effort, dealing with different spatial resolution and extents, harmonizing measurement units from different data sources or sampling methods, applying statistical tools and models for spatial inter- or extrapolation, and quantifying sources of uncertainty and errors in data and models. To support the development of EBVs by the Group on Earth Observations Biodiversity Observation Network (GEO BON), we identify 11 key workflow steps that will operationalize the process of building EBV data products within and across research infrastructures worldwide. These workflow steps take multiple sequential activities into account, including identification and aggregation of various raw data sources, data quality control, taxonomic name matching and statistical modelling of integrated data. We illustrate these steps with concrete examples from existing citizen science and professional monitoring projects, including eBird, the Tropical Ecology Assessment and Monitoring network, the Living Planet Index and the Baltic Sea zooplankton monitoring. The identified workflow steps are applicable to both terrestrial and aquatic systems and a broad range of spatial, temporal and taxonomic scales. They depend on clear, findable and accessible metadata, and we provide an overview of current data and metadata standards. Several challenges remain to be solved for building global EBV data products: (i) developing tools and models for combining heterogeneous, multi-source data sets and filling data gaps in geographic, temporal and taxonomic coverage, (ii) integrating emerging methods and technologies for data collection such as citizen science, sensor networks, DNA-based techniques and satellite remote sensing, (iii) solving major technical issues related to data product structure, data storage, execution of workflows and the production process/cycle as well as approaching technical interoperability among research infrastructures, (iv) allowing semantic interoperability by developing and adopting standards and tools for capturing consistent data and metadata, and (v) ensuring legal interoperability by endorsing open data or data that are free from restrictions on use, modification and sharing. Addressing these challenges is critical for biodiversity research and for assessing progress towards conservation policy targets and sustainable development goals.
Commonness and rarity determinants of woody plants in different types of tropical forests
(Springer Science+Business Media, 2014) Gabriel Arellano; M. Isabel Loza; J. Sebastián Tello; Manuel J. Macía
Community structure and abundance of small rodents at the wave front of agroforestry and forest in Alto Beni, Bolivia
(2020) Susana G. Revollo-Cadima; Adriana Rico C.; Luis F. Pacheco; Jorge Salazar‐Bravo
Comparison of density estimation methods for mammal populations with camera traps in the <scp>K</scp>aa‐<scp>I</scp>ya del <scp>G</scp>ran <scp>C</scp>haco landscape
(Wiley, 2012) A. J. Noss; B. Gardner; Leonardo Maffei; Erika Cuéllar; R. Montaño; Alfredo Romero‐Muñoz; R. Sollman; Allan F. O’Connell
Abstract Sampling animal populations with camera traps has become increasingly popular over the past two decades, particularly for species that are cryptic, elusive, exist at low densities or range over large areas. The results have been widely used to estimate population size and density. We analyzed data from 13 camera trap surveys conducted at five sites across the K aa‐ I ya landscape, B olivian C haco, for jaguar, puma, ocelot and lowland tapir. We compared two spatially explicit capture–recapture ( SCR ) software packages: secr , a likelihood‐based approach, and SPACECAP , a B ayesian approach, both of which are implemented within the R environment and can be used to estimate animal density from photographic records of individual animals that simultaneously employ spatial information about the capture location relative to the sample location. As a non‐spatial analysis, we used the program CAPTURE 2 to estimate abundance from the capture–recapture records of individuals identified through camera trap photos combined with an ad hoc estimation of the effective survey area to estimate density. SCR methods estimated jaguar population densities from 0.31 to 1.82 individuals per 100 km 2 across the K aa‐ I ya sites; puma from 0.36 to 7.99; ocelot from 1.67 to 51.7; and tapir from 7.38 to 42.9. Density estimates using either secr or SPACECAP were generally lower than the estimates generated using the non‐spatial method for all surveys and species; and density estimates using SPACECAP were generally lower than that using secr . We recommend using either secr or SPACECAP because the spatially explicit methods are not biased by an informal estimation of an effective survey area. Although SPACECAP and secr are less sensitive than non‐spatial methods to the size of the grid used for sampling, we recommend grid sizes several times larger than the average home range (known or estimated) of the target species.
Comparisons of assemblages of phytoplankton between open water and seagrass habitats in a shallow coastal lagoon
(CSIRO Publishing, 2004) S. P. Cummins; Daniel Roberts; Penelope Ajani; A.J. Underwood
Patterns of phytoplankton in areas with seagrass (Zostera capricorni, Halophila ovalis, and Ruppia megacarpa) and areas without seagrass were quantified in an estuary near Sydney, NSW, Australia. Replicate samples (separated by metres) were collected on 20 randomly chosen occasions over almost 3 years, from two sites (separated by tens of metres) nested in both habitats, at four locations (separated by kilometres). Areas with seagrass often supported a significantly different assemblage of phytoplankton compared with areas without seagrass. Dissimilarities were due to small differences in the relative abundance of taxa, particularly the diatom Pseudonitzschia cf. pseudodelicatissima, rather than the presence or absence of specific taxa. In both habitats, abundances of phytoplankton were patchy at all of the spatial scales sampled, although most of the variation was among replicate samples. These findings emphasise the need to incorporate a hierarchy of scales in programs designed to understand processes that cause spatial and temporal patterns of phytoplankton or to detect changes in response to human activities.