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1. Water availability is the main determinant of species' distribution in lowland tropical forests. Species' occurrence along water availability gradients depends on their ability to tolerate drought. 2. To identify species' trait...
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1. Water availability is the main determinant of species' distribution in lowland tropical forests. Species' occurrence along water availability gradients depends on their ability to tolerate drought. 2. To identify species' traits underlying drought-tolerance we excavated first year seedlings of 62 dry and moist forest tree species at the onset of the dry season. We evaluate how morphological seedling traits differ between forests, and whether functional groups of species can be identified based on trait relations. We also compare seedling traits along independent axes of drought and shade-tolerance to assess a hypothesized trade-off. 3. Seedlings of dry forest species improve water foraging capacity in deep soil layers by an increased below-ground biomass allocation and by having deep roots. They minimize the risk of cavitation by making dense stems, and reduce transpiration by producing less leaf tissue. Moist forest seedlings have large leaf areas and a greater above-ground biomass, to maximize light interception, and long, cheap, branched root systems, to increase water and nutrient capture. 4. Associations among seedling traits reveal three major drought strategies: (i) evergreen drought-tolerant species have high biomass investment in enduring organs, minimize cavitation and minimize transpiration to persist under dry conditions; (ii) drought-avoiding species maximize resource capture during a limited growing season and then avoid stress with a deciduous leaf habit in the dry season; (iii) drought-intolerant species maximize both below- and above-ground resource capture to increase competitiveness for light, but are consequently precluded from dry habitats. 5. We found no direct trade-off between drought- and shade-tolerance, because they depend largely on different morphological adaptations. Drought-tolerance is supported by a high biomass investment to the root system, whereas shade-tolerance is mainly promoted by a low growth rate and low SLA. 6. Synthesis. We conclude that there are three general adaptation strategies of drought-tolerance, which seemingly hold true across biomes and for different life forms. Drought- and shade-tolerance are largely independent from one another, suggesting a high potential for niche differentiation, as species' specialization can occur at different combinations of water and light availability.
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We estimated the crustal thickness along an east-west transect across the Andes at lat 20 degrees S and along a north-south transect along the eastern edge of the Altiplano from data recorded on two arrays of portable broadband se...
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We estimated the crustal thickness along an east-west transect across the Andes at lat 20 degrees S and along a north-south transect along the eastern edge of the Altiplano from data recorded on two arrays of portable broadband seismic stations (BANJO and SEDA). Waveforms of deep regional events in the downgoing Nazca slab and teleseismic earthquakes were processed to isolate the P-to-S converted phases from the Moho in order to compute the crustal thickness. We found crustal-thickness variations of nearly 40 km across the Andes, Maximum crustal thicknesses of 70-74 km under the Western Cordillera and the Eastern Cordillera thin to 32-38 km 200 km east of the Andes in the Chaco Plain. The central Altiplano at 20 degrees S has crustal thicknesses of 60 to 65 km. The crust also appears to thicken from north (16 degrees S, 55-60 km) to south (20 degrees S, 70-74 km) along the Eastern Cordillera, The Subandean zone crust has intermediate thicknesses of 43 to 47 km. Crustal-thickness predictions for the Andes based on Airy-type isostatic behavior show remarkable overall correlation with observed crustal thickness in the regions of high elevation, In contrast, at the boundary between the Eastern Cordillera and the Subandean zone and in the Chaco Plain, the crust is thinner than predicted, suggesting that the crust in these regions is supported in part by the flexural rigidity of a strong lithosphere, With additional constraints, we conclude that the observation of Airy-type isostasy is consistent with thickening associated with compressional shortening of a weak lithosphere squeezed between the stronger lithosphere of the subducting Nazca plate and the cratonic lithosphere of the Brazilian craton. [References: 26]
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Covid-19 has not only affected the health of the population but has also deteriorated the economies and industries of the countries; one of them, which is the most affected, is undoubtedly tourism. The impact of the Covid-19 on th...
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Covid-19 has not only affected the health of the population but has also deteriorated the economies and industries of the countries; one of them, which is the most affected, is undoubtedly tourism. The impact of the Covid-19 on the Bolivian tourism industry warned that about 3,020 million BOB $ would be lost in 2020. The main receptive inbound markets in Bolivia drastically decreased their trips and the impact derived from the absence of tourism caused more than 140 thousand people to lose their job source. Undoubtedly, the tourism micro entrepreneur was the one who received the greatest impact, since nearly 50% of the productive units closed operations in the months following the start of the pandemic. However, Bolivian entrepreneurs saw in this interruption an opportunity to think and reinvent themselves by migrating to the computer world.
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Novos Onciderini (Coleoptera, Cerambycidae) da Bolívia. Novas espécies de Onciderini sao descritas da Bolívia, Santa Cruz, Buena Vista (Hotel Flora & Fauna): Trestoncideres albiventris sp. nov., Trestonia morrisi sp. nov. e Oncideres wappesi sp. nov. Baseados em material enviado para estudo por James Wappes, descrevemos três espécies da tribo Onciderini que foi objeto de revisao por Dillon & Dillon (1945, 1946). Após essa revisao muitos trabalhos foram publicados sobre essa tribo que necessitade outra revisao para ampliar aquela de Dillon & Dillon....
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Novos Onciderini (Coleoptera, Cerambycidae) da Bolívia. Novas espécies de Onciderini sao descritas da Bolívia, Santa Cruz, Buena Vista (Hotel Flora & Fauna): Trestoncideres albiventris sp. nov., Trestonia morrisi sp. nov. e Oncideres wappesi sp. nov. Baseados em material enviado para estudo por James Wappes, descrevemos três espécies da tribo Onciderini que foi objeto de revisao por Dillon & Dillon (1945, 1946). Após essa revisao muitos trabalhos foram publicados sobre essa tribo que necessitade outra revisao para ampliar aquela de Dillon & Dillon.
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We describe ten new species ofPolystichum (Dryopteridaceae, Pteridophyta) from Bolivia, provide brief notes on the other eleven species of the genus in the country, and present a key to all species, New species are:P. albomarginat...
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We describe ten new species ofPolystichum (Dryopteridaceae, Pteridophyta) from Bolivia, provide brief notes on the other eleven species of the genus in the country, and present a key to all species, New species are:P. albomarginatum, P. amboroense, P. bachii, P. chaparensis, P. congestum, P. giganteum, P. lepidotum, P. paramicola, P. rufum, andP. solomonii.
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Bolivia's forests contribute to the global carbon and water cycle, as well as to global biodiversity. The survival of these forests may be at risk due to climate change. To explore the associated mechanisms and uncertainties, a re...
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Bolivia's forests contribute to the global carbon and water cycle, as well as to global biodiversity. The survival of these forests may be at risk due to climate change. To explore the associated mechanisms and uncertainties, a regionally adapted dynamic vegetation model was implemented for the Bolivian case, and forced with two contrasting climate change projections. Changes in carbon stocks and fluxes were evaluated, factoring out the individual contributions of atmospheric carbon dioxide ([CO_2]), temperature, and precipitation. Impacts ranged from a strong increase to a severe loss of vegetation carbon (c_v), depending on differences in climate projections, as well as the physiological response to rising [CO_2]. The loss of c_v simulated for an extremely dry projection was primarily driven by a reduction in gross primary productivity, and secondarily by enhanced emissions from fires and autotrophic respiration. In the wet forest, less precipitation and higher temperatures equally reduced c_v, while in the dry forest, the impact of precipitation was dominating. The temperature-related reduction of c_v was mainly due to a decrease in photosynthesis and only to lesser extent because of more autotrophic respiration and less stomatal conductance as a response to an increasing atmospheric evaporative demand. Under an extremely dry projection, tropical dry forests were simulated to virtually disappear, regardless of the potential fertilizing effect of rising [CO_2]. This suggests a higher risk for forest loss along the drier southern fringe of the Amazon if annual precipitation will decrease substantially.
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Baguatherium jaureguii gen. et sp. nov. from the early Oligocene of northern Peru is the best known pre-Deseadan pyrothere. It has a relatively wider palate and less oblique lophs on the molariform teeth than Pyrotherium macfadden...
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Baguatherium jaureguii gen. et sp. nov. from the early Oligocene of northern Peru is the best known pre-Deseadan pyrothere. It has a relatively wider palate and less oblique lophs on the molariform teeth than Pyrotherium macfaddeni and Pyrotherium romeroi. A conspicuous lingual crest connects the anterior and posterior lophs of molariform teeth. Nares are retracted. Phylogenetic analysis places Baguatherium with Gryphodon and Pyrotherium in an unresolved polytomy. In Proticia and Colombitherium the wear facets of the molariform teeth indicate a mainly grinding masticatory apparatus. In Pyrotherium, Baguatherium, Gryphodon, and to a lesser degree, Propyrotherium, the oblique wear facets generate a cutting surface caused by a greater antero-posterior component to dorsoventral mastication. The cingulae function like stops or buttresses. Considering its brachydont condition, this,specialization and the increase in the molariform surface in Baguatherium and Pyrotherium may have improved masticatory efficiency in response to the expansion of open environments during the Oligocene.
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The distributions of forest and deforestation throughout the tropice are poorly known despite their importance to regional biodiversity and global climate and biodiversity. Deforestation estimates based on surveys or sampling have...
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The distributions of forest and deforestation throughout the tropice are poorly known despite their importance to regional biodiversity and global climate and biodiversity. Deforestation estimates based on surveys or sampling have large errors, and high-resolution wall-to-wall mapping of tropical forests is necessary to assess the impacts of fragmen- tation. Landsat satellite images from the mid-1980s and early 1990s were thus used to map closed-canopy tropical forest extent and anthropogenic deforestation in an approximately 700 000 km~2 area of Amazoian Bolivia with precipitation > 1000 mm yr~-1.
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Los estudios paleontolOgicos sobre las ayes del Cuaternario de America del Sur son cuantitativamente muy inferiores a aquellos referidos a los mamiferos y estan centrados sobre regiones o sitios fosiliferos muy localizados (Tambus...
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Los estudios paleontolOgicos sobre las ayes del Cuaternario de America del Sur son cuantitativamente muy inferiores a aquellos referidos a los mamiferos y estan centrados sobre regiones o sitios fosiliferos muy localizados (Tambussi et al., 1993;Tambussi, 1995). Las contribuciones resultan de esta manera muy escasas en relacion con la amplia extension de los afloramientos de esa antiguedad en la totalidad del continente.
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