Thibeault J.M.,University of Connecticut |
Seth A.,University of Connecticut |
Garcia M.,Higher University of San Andres
Journal of Geophysical Research: Atmospheres | Year: 2010
Rural agriculture in the Bolivian Altiplano is vulnerable to climate related shocks including drought, frost, and flooding. We examine multimodel, multiscenario projections of eight precipitation and temperature extreme indices for the Altiplano and compute temperature indices for La Paz/Alto, covering 1973-2007. Significant increasing trends in observed warm nights and warm spells are consistent with increasing temperatures in the tropical Andes. The increase in observed frost days is not simulated by the models in the 20th century, and projections of warm nights, frost days, and heat waves are consistent with projected annual cycle temperature increases; PDFs are outside their 20th century ranges by 2070-2099. Projected increases in precipitation extremes share the same sign as observed trends at Patacamaya and are consistent with annual cycle projections indicating a later rainy season characterized by less frequent, more intense precipitation. Patacamaya precipitation indices show shifts in observed distributions not seen in the models until 2020-2049, implying that precipitation changes may occur earlier than projected. The observed increase in frost days can be understood within the context of precipitation changes and an increase in radiative cooling. Model warm/wet biases suggest that a decrease in frost days may not occur as early or be as large as projected. Nevertheless, consistencies between simulated and observed extremes, other than frost days, suggest the directions of projected changes are reliable. These results are a first step toward providing the critical information necessary to reduce threats to food security and water resources in the Altiplano from changing climate. Copyright 2010 by the American Geophysical Union.
Chang C.-C.,National Cheng Kung University |
Soruco Carballo C.F.,National Cheng Kung University |
Soruco Carballo C.F.,Higher University of San Andres
Energy Policy | Year: 2011
This study examines the causal relationships among energy consumption, economic growth and carbon dioxide emissions in twenty countries from Latin America and the Caribbean region. The methodology includes the use of Phillips and Perron (PP) tests, a cointegration model with vector error correction modeling (VECM) and vector autoregression (VAR) with Granger causality. The study concludes that of the twenty countries analyzed, only in four of them will it be possible to implement energy conservation polices without affecting their economic growth, four others are not able to consider an energy conservation policy with economic growth, and the other twelve should focus on their economic growth before adopting any conservation policies. Energy efficiency was found in this region, especially in the countries which have both cointegration and short-term equilibrium. © 2011 Elsevier Ltd.
Montano-Centellas F.A.,Higher University of San Andres
Ornitologia Neotropical | Year: 2012
Yungas Manakins (Chiroxiphia boliviana) are small understorey frugivorous birds with a lekbased mating system and sexual dimorphism. As sexes differ in feeding-related traits, I examined whether they also differ in their diets and role as seed dispersers. Although restricted by sample sizes, my results suggest that sexes are not redundant as seed dispersers. They do differ in their diets yet following a pattern contrary to expectations. Males disperse more seed species including several batdispersed seeds but are less effective dispersers than females, while the latter seem to be especially important for melastome berries' dispersal. Bill dimorphism does not explain fruit consumption differences, but behavioral dimorphism does. © The Neotropical Ornithological Society.
Montano-Centellas F.A.,Higher University of San Andres
Biotropica | Year: 2013
The dependence of mistletoes on few dispersers and the directed dispersal they provide is well known, yet no recent work has quantified either the effectiveness of these 'legitimate' dispersers, or the extent of redundancy among them. Here, I use the seed dispersal effectiveness (SDE) framework to analyze how birds (Mionectes striaticollis and Zimmerius bolivianus) contribute to mistletoe (Struthanthus acuminatus and Phthirusa retroflexa) infection in traditional mixed plantations within a humid montane forest in Bolivia. I calculated SDE for each bird-mistletoe pair and for the disperser assemblage, by estimating both the quantity and the quality of dispersal. The quantity of dispersal was measured as: (1) disperser abundance; (2) frequency of visits; and (3) number of seeds dispersed per visit, and the quality of dispersal was measured as: (1) germination percentage and speed of germination of seeds regurgitated by birds; and (2) the concordance of deposited seeds and seedling distribution patterns with adult mistletoe distribution at three scales (habitat, host, and microhabitat). Dispersers were not redundant: the more generalist species M. striaticollis dispersed more seeds, but provided lower quality seed dispersal, whereas the mistletoe specialist Z. bolivianus provided low-quantity and high-quality seed dispersal. Whereas S. acuminatus benefited more from the SDE of Z. bolivianus, P. retroflexa benefited from the complementary seed dispersal provided by both birds. These results demonstrate how sympatric mistletoes that share the same disperser assemblage may develop different relationships with specific vectors, and describe how the services provided by two different dispersers (one that provides high-quality and one that provides high-quantity dispersal) interact to shape spatial patterns of plants. © 2012 by The Association for Tropical Biology and Conservation.
Dishisha T.,Lund University |
Alvarez M.T.,Lund University |
Alvarez M.T.,Higher University of San Andres |
Hatti-Kaul R.,Lund University
Bioresource Technology | Year: 2012
Propionic acid production from glycerol was studied using Propionibacterium acidipropionici DSM 4900 cells immobilized on polyethylenimine-treated Poraver (PEI-Poraver) and Luffa (PEI-Luffa), respectively. Using PEI-Luffa, the average productivity, yield and concentration of propionic acid from 40gL -1 glycerol were 0.29gL -1h -1, 0.74mol PAmol Gly -1 and 20gL -1, respectively, after four consecutive recycle-batches. PEI-Poraver supported attachment of 31 times higher amounts of cells than PEI-Luffa and produced 20, 28 and 35gL -1 propionic acid from 40, 65 and 85gL -1 glycerol, respectively (0.61molPAmolGly-1). The corresponding production rates were 0.86, 0.43 and 0.35gL -1h -1, which are the highest reported from glycerol via batch or fed-batch fermentations for equivalent propionic acid concentrations. Using a continuous mode of operation at a dilution rate of 0.1h -1, cell washout was observed in the bioreactor with free cells; however, propionic acid productivity, yield and concentration were 1.40gL -1h -1, 0.86molPAmolGly-1, and 15gL -1, respectively, using immobilized cells in the PEI-Poraver bioreactor. The choice of the immobilization matrix can thus significantly influence the fermentation efficiency and profile. The bioreactor using cells immobilized on PEI-Poraver allowed the fermentation of higher glycerol concentrations and provided stable and higher fermentation rates than that using free cells or the cells immobilized on PEI-Luffa. © 2012 Elsevier Ltd.