Ecology
Amazonian forests are a vast storehouse of biodiversity and function as carbon sinks from biomass that accumulates in various tree species. In these forests, the taxa with the greatest contribution of biomass cannot be precisely defined,... more
Amazonian forests are a vast storehouse of biodiversity and function as carbon sinks from biomass that accumulates
in various tree species. In these forests, the taxa with the
greatest contribution of biomass cannot be precisely defined, and the representative distribution of Myristicaceae in the Peruvian Amazon was the starting point for designing the
present study, which aimed to quantify the biomass contribution of this family. For this, I analyzed the databases
that corresponded to 38 sample units that were previously collected and that were provided by the TeamNetwork
and RAINFOR organizations. The analysis consisted in the estimation of biomass using pre-established allometric
equations, Kruskal-Wallis sample comparisons, interpolation-analysis maps, and nonparametric multidimensional
scaling (NMDS). The results showed that Myristicaceae is
the fourth most important biomass contributor with 76.97Mg/ha (9.92Mg/ha in average), mainly due to its abundance. Additionally, the family shows a noticeable
habitat preference for certain soil conditions in the physiographic units, such is the case of Virola pavonis
in “varillales”, within “floodplain”, or Iryanthera tessmannii and Virola loretensis in sewage flooded areas or “igapó” specifically,
and the preference of Virola elongata and Virola surinamensis for white water flooded areas or “várzea” edaphic conditions of the physiographic units taken in the study.
in various tree species. In these forests, the taxa with the
greatest contribution of biomass cannot be precisely defined, and the representative distribution of Myristicaceae in the Peruvian Amazon was the starting point for designing the
present study, which aimed to quantify the biomass contribution of this family. For this, I analyzed the databases
that corresponded to 38 sample units that were previously collected and that were provided by the TeamNetwork
and RAINFOR organizations. The analysis consisted in the estimation of biomass using pre-established allometric
equations, Kruskal-Wallis sample comparisons, interpolation-analysis maps, and nonparametric multidimensional
scaling (NMDS). The results showed that Myristicaceae is
the fourth most important biomass contributor with 76.97Mg/ha (9.92Mg/ha in average), mainly due to its abundance. Additionally, the family shows a noticeable
habitat preference for certain soil conditions in the physiographic units, such is the case of Virola pavonis
in “varillales”, within “floodplain”, or Iryanthera tessmannii and Virola loretensis in sewage flooded areas or “igapó” specifically,
and the preference of Virola elongata and Virola surinamensis for white water flooded areas or “várzea” edaphic conditions of the physiographic units taken in the study.
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Intraspecific variation can have important knock-on effects on population dynamics and ecosystem processes. There are good indicators that intraspecific differences may exist in the foraging ecology of kea parrots (Nestor notabilis). Kea... more
Intraspecific variation can have important knock-on effects on population dynamics and ecosystem
processes. There are good indicators that intraspecific differences may exist in the foraging ecology of kea
parrots (Nestor notabilis). Kea breed in two markedly different habitats (alpine and temperate rainforest), and
have pronounced sexual size dimorphism of their upper bill, which may indicate niche partitioning between
the sexes. Additionally, as a long-lived species, they can potentially acquire a vast amount of information
regarding food sources within their environment, suggesting variation between age classes. We used field
observations and faecal analysis to investigate the foraging ecology of kea. We found evidence of invertebrate
foraging significantly more frequently in temperate rainforest than in alpine regions, where kea foraged more
frequently on fruit. In the alpine habitat, kea fed mainly on fruit during summer and autumn, changing primarily
to leaves during winter and spring and increasing invertebrate consumption in springtime. Although there was
no discernible impact of sex, we found that adult males foraged more on roots and invertebrates than immature
kea, possibly because they were able to exploit a more varied diet through experience. Future research should
investigate the relationship between invertebrate foraging and breeding ecology in kea.
processes. There are good indicators that intraspecific differences may exist in the foraging ecology of kea
parrots (Nestor notabilis). Kea breed in two markedly different habitats (alpine and temperate rainforest), and
have pronounced sexual size dimorphism of their upper bill, which may indicate niche partitioning between
the sexes. Additionally, as a long-lived species, they can potentially acquire a vast amount of information
regarding food sources within their environment, suggesting variation between age classes. We used field
observations and faecal analysis to investigate the foraging ecology of kea. We found evidence of invertebrate
foraging significantly more frequently in temperate rainforest than in alpine regions, where kea foraged more
frequently on fruit. In the alpine habitat, kea fed mainly on fruit during summer and autumn, changing primarily
to leaves during winter and spring and increasing invertebrate consumption in springtime. Although there was
no discernible impact of sex, we found that adult males foraged more on roots and invertebrates than immature
kea, possibly because they were able to exploit a more varied diet through experience. Future research should
investigate the relationship between invertebrate foraging and breeding ecology in kea.
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Positive interspecific interactions can shape fundamental wetland ecosystem dynamics, including energy transfer and spatial distribution of nutrients. Birds, by foraging in one location and nesting in another, commonly act as... more
Positive interspecific interactions can shape fundamental wetland ecosystem dynamics, including energy transfer and spatial distribution of nutrients. Birds, by foraging in one location and nesting in another, commonly act as between-ecosystem nutrient vectors. However, the distribution of nutrients within nesting areas and mechanisms of transfer to other trophic levels are poorly understood. We report on measurements of available food transferred from nesting long-legged wading birds to American alligators (Alligator mississippiensis) in the Everglades of Florida, USA. Using throughfall traps, a historic dataset on nesting success and a literature-parameterized alligator energy budget, we estimated the potential food available to alligators via regurgitant and nestling carcasses, and compared that to alligator food requirements. Although dropped regurgitant is of little importance to scavenging alligators, we estimate that nestling carcasses throughout the ecosystem could support the energetic requirements of hundreds of alligators for periods of several months. This resource occurs during the dry season, when alligator thermoregulatory opportunities are relatively scarce and female alligators are mobilizing resources for egg-laying. Our results indicate that through fallen nestlings, wading bird nesting colonies have strong potential to benefit alligators. This facilitative exchange may be globally widespread, forming a keystone process in many tropical and subtropical wetlands.
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Contributions from the field of population biology hold promise for understanding and managing invasiveness; invasive species also offer excellent opportunities to study basic processes in population biology. Life history studies and... more
Contributions from the field of population biology hold promise for understanding and managing invasiveness; invasive species also offer excellent opportunities to study basic processes in population biology. Life history studies and demographic models may be valuable for examining the introduction of invasive species and identifying life history stages where management will be most effective. Evolutionary processes may be key features in determining whether invasive species establishand spread. Studies of genetic diversity and evolutionary changes should be useful for understanding the potential for colonization and establishment, geographic patterns of invasion and range expansion, lag times, and the potential for evolutionary responses to novel environments, including management practices. The consequences of biological invasions permit study of basic evolutionary processes, as invaders often evolve rapidly in response to novel abiotic and biotic conditions, and native species evolve in response to the invasion.
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In this study, we evaluate the effects of spatial and environmental factors on the structure of tadpole assemblages in Central Amazonia testing the following hypotheses: (1) environmental factors are more important than spatial ones in... more
In this study, we evaluate the effects of spatial and environmental factors on the structure of tadpole assemblages in Central Amazonia testing the following hypotheses: (1) environmental factors are more important than spatial ones in tadpole richness distribution and (2) habitat structure variables are more important than biotic variables in tadpole richness distribution. Tadpoles were sampled at 20 riparian plots between February and June 2010. Spatial and environmental components explained the major part of the variation in observed and estimated tadpole richness, respectively. Among all fitted models, the best model that explains species richness distribution is the one that contains only the number of ponds. Our results showed that tadpole richness in streamside ponds is influenced by niche-based processes and can be explained by local factors related to habitat structure. Predator density was not an important biotic factor in our study, contradicting the results found by other studies conducted in tropical areas. However, neutral processes are also important because spatial variation can explain the spatial distribution of species richness, probably as a result of dispersal limitation. Therefore, our results contribute to understanding of the local and landscape features which influence the amphibian species diversity in a tropical forest.
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16th September 2015 to be held at Trinity College, a workshop/conference on the Reform of Economics
facilitited in part by economics students wanting change and explanations of todays pressures and crises
facilitited in part by economics students wanting change and explanations of todays pressures and crises
Research Interests: Business Ethics, Social Movements, Environmental Science, Economics, Environmental Economics, and 27 moreInternational Relations, Political Economy, Philosophy, Political Philosophy, Ethics, Normative Ethics, Social Sciences, Corporate Social Responsibility, Climate Change, Conservation Biology, International Law, Conservation, Political Ecology, Social and Cultural Anthropology, Climate change policy, Political Science, Social Justice, International Political Economy, Philosophy Of Law, Environmental Ethics, Ecology, Social History, Biodiversity, Environmental Sustainability, Wildlife Conservation, Ethics and economics, and Impact of Social Sciences and Humanities
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A recently developed system dynamics model specifies a new hypothesis for the extinctions at the end of the Pleistocene - Second Order Predation - and compares it with the overkill hypothesis (see http://quaternary.net/extinct2000). It... more
A recently developed system dynamics model specifies a new hypothesis for the extinctions at the end of the Pleistocene - Second Order Predation - and compares it with the overkill hypothesis (see http://quaternary.net/extinct2000). It provides a quantitative description of the interrelationships between four plant stocks, four herbivore stocks, carnivores, and H. sapiens. Different assumptions regarding H. sapiens in-migration, hunting of
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In the 1980s, anthropologists argued that tropical rainforests were unattractive environments for long-term human navigation, subsistence and occupation. Meanwhile, archaeologists have traditionally held that Homo sapiens only intensively... more
In the 1980s, anthropologists argued that tropical rainforests were unattractive environments for long-term human navigation, subsistence and occupation. Meanwhile, archaeologists have traditionally held that Homo sapiens only intensively colonized rainforests during the Holocene, from c. 11 thousand years ago (ka). New discoveries and re-appraisal of Pleistocene (c. 200–12 ka) archaeological sites in Africa, Southeast Asia, Melanesia, and Sri Lanka, have, however, indicated the possibility for human occupation of rainforests from c. 45 ka and, more controversially, c. 200 ka. We critically review the archaeological evidence for Pleistocene human rainforest occupation from several regions. We argue that clear evidence exists for human adaptation to rainforest ecologies from c. 45 ka, with tantalizing hints of even earlier colonization. More research, however, is needed in order to understand the dynamism and diversity of palaeoecologies commonly classified as ‘rainforest’, as well as the regional extent, nature, and longevity of early human rainforest habitations.
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Comprehension of changes in community composition through multiple spatio-temporal scales is a prime challenge in ecology and palaeobiology. However, assembly, structuring and disassembly of biotic metacommunities in deep-time is... more
Comprehension of changes in community composition through multiple spatio-temporal scales is a prime challenge in ecology and palaeobiology. However, assembly, structuring and disassembly of biotic metacommunities in deep-time is insufficiently known. To address this, we used the extensively sampled Iberian Plio-Pleistocene fossil record of rodent faunas as our model system to explore how global climatic events may alter metacommunity structure. Through factor analysis, we found five sets of genera, called faunal components, which co-vary in proportional diversity over time. These faunal components had different spatio-temporal distributions throughout the Plio-Pleistocene, resulting in non-random changes in species assemblages, particularly in response to the development of the Pleistocene glaciations. Three successive metacommunities with distinctive taxonomic structures were identified as a consequence of the differential responses of their members to global climatic change: (1) Ruscinian subtropical faunas (5.3–3.4 Ma) dominated by a faunal component that can be considered as a Miocene legacy; (2) transition faunas during the Villafranchian–Biharian (3.4–0.8 Ma) with a mixture of different faunal components; and (3) final dominance of the temperate Toringian faunas (0.8–0.01 Ma) that would lead to the modern Iberian assemblage. The influence of the cooling global temperature drove the reorganisation of these rodent metacommunities. Selective extinction processes due to this large-scale environmental disturbance progressively eliminated the subtropical specialist species from the early Pliocene metacommunity. This disassembly process was accompanied by the organisation of a diversified metacommunity with an increased importance of biome generalist species, and finally followed by the assembly during the middle–late Pleistocene of a new set of species specialised in the novel environments developed as a consequence of the glaciations.
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Extremes in rangeland management, varying from too-frequent fire and intensive grazing to the suppression of both, threaten rangeland ecosystems worldwide. Intensive fire and grazing denude and homogenize vegetation whereas their... more
Extremes in rangeland management, varying from too-frequent fire and intensive grazing to the suppression of both, threaten rangeland ecosystems worldwide. Intensive fire and grazing denude and homogenize vegetation whereas their suppression increases woody cover. Although habitat loss is implicated in grassland bird declines, degradation through intensive management or neglect also decreases breeding habitat and may reduce nesting success through increased rates of nest predation. Snakes are important nest predators, but little is known about how habitat use in snakes relates to predation risk for grassland birds nesting within tallgrass prairie subjected to different grazing and fire frequencies. We evaluated nest survival in the context of habitat used by nesting songbirds and two bird-eating snakes, the eastern yellowbelly racer Coluber constrictor flaviventris and Great Plains ratsnake Pantherophis emoryi. Daily nest survival rates decreased with increasing shrub cover and decreasing vegetation height, which characterize grasslands that have been neglected or intensively managed, respectively. Discriminant function analysis revealed that snake habitats were characterized by higher shrub cover, whereas successful nests were more likely to occur in areas with tall grass and forbs but reduced shrub cover. Because snakes often use shrub habitat, birds nesting in areas with increased shrub cover may be at higher risk of nest predation by snakes in addition to other predators known to use shrub habitat (e.g., mid-sized carnivores and avian predators). Depredated nests also occurred outside the discriminant space of the snakes, indicating that other predators (e.g., ground squirrels Spermophilus spp. and bullsnakes Pituophis catenifer) may be important in areas with denuded cover. targeted removal of shrubs may increase nest success by minimizing the activity of nest predators attracted to shrub cover.