Ken Oyama

Universidad Nacional Autónoma de México, Ciudad de México, Mexico City, Mexico

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Publications (76)174.54 Total impact

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    ABSTRACT: Foliar nutrient resorption (FNR) is a key process in the dynamics of nutrients in a forest ecosystem. Along with other factors, FNR regulates the chemical composition of the forest floor and, consequently, the rates of organic matter decomposition and soil nutrient availability. The main objective of the present study was to examine the effect of FNR of two deciduous oak species (Quercus castanea and Q. deserticola) in the litter and soil nutrient dynamics, in addition to analyze whether the interaction between two species was positive (synergistic) or negative (antagonistic) through the mixed litter from two species. For this purpose, the nutrient concentration of green leaves, litterfall, litter and soil was measured, as well as soil microbial activity. These measurements were taken in isolated stands with the presence of one of the oak species and stands with the two oak species mixed. Quer-cus deserticola, with lower FNR, produced litter with a higher N concentration, which apparently enhancing microbial activity in the forest floor litter and increased nutrient transformations and soil fertility. In contrast, Q. castanea has a higher FNR and produced litter with a lower nutrient concentration. The microbial soil community associated with Q. castanea must therefore invest more energy in metabolic processes at the expense of biomass growth. However, forest floor nutrient transformations were more intense and soil fertility increased in areas where both species intermix; in this case, the latter species received the rich-nutrient litterfall of Q. deserticola. These results suggest a strong footprint of species traits on microbial activities and soil nutrient transformations.
    European Journal of Forest Research 06/2015; DOI:10.1007/s10342-015-0891-1 · 1.68 Impact Factor
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    ABSTRACT: Repeated use of sleeping trees (STs) by frugivores promotes the deposition and aggregation of copious amounts of seed, thus having key implications for seed dispersal and forest regeneration. Seed-rain patterns produced by this behaviour likely depend on the frequency of use of these sites, yet this hypothesis has been poorly tested. We evaluated community-level seed-rain patterns produced by the spider monkey (Ateles geoffroyi) over 13 mo in latrines located beneath 60 STs in the Lacandona rain forest, Mexico. Because this primate is increasingly ‘forced’ to inhabit fragmented landscapes, we tested whether sleeping-tree fidelity (STF) differed among sites and between continuous and fragmented forests.We also testedwhether seed-rain patternswere associated with STFwithin each site and forest type. STF was highly variable among STs (average =7mo, range = 1–12 mo), but did not differ among study sites or forest types. STF was positively associated with seed abundance, species diversity and species turnover. Nevertheless, STF tended to be negatively related to seed community evenness. These results are likely due to the most frequently used STs being in areas with greater food density. Our results demonstrate that site fidelity shapes community-level seed-rain patterns and thus has key ecological implications.
    Journal of Tropical Ecology 06/2015; 31(04):305-307. DOI:10.1017/S026646741500022X · 1.22 Impact Factor
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    ABSTRACT: We explore the impact of habitat fragmentation on interactions between keystone resources of forest trees—oaks, genus Quercus (Fagaceae)—and an associated radiation of specialist cynipid gall wasps. Habitat fragmentation is predicted to have bottom-up impacts on cynipid communities through impacts on host plant quality (plant vigor hypothesis). We explored the bottom-up impacts on cynipid communities of habitat fragment size, fragment edge effects and presence of isolated oaks. We quantified temporal and spatial variation of leaves produced in the canopy to quantify plant vigor, and surveyed cynipid gall species abundance and richness over three years using 15 permanent forest patches and 25 isolated oaks in a fragmented oak woodland landscape in central Mexico. Cynipid gall abundance and species richness were higher in isolated oaks and small woodland fragments than in larger ones. Cynipid abundance and species richness were also higher along fragment edges in comparison with fragment interiors. This contrasts with patterns observed in other taxa. In addition, host plant quality was higher in isolated trees, in smaller fragments and along fragment edges. We therefore hypothesize that observed patterns in cynipid abundance and species richness are driven by changes in host plant quality due to forest fragmentation. Our data represent a baseline for longer-term monitoring of fragmentation effects at a landscape scale. Further work is required to explore alternative potential explanations for observed patterns, including the estimation of potential top-down impacts of fragmentation mediated by natural enemies.
    Ecosphere 03/2015; 6(3):31. DOI:10.1890/ES14-00355.1 · 2.60 Impact Factor
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    ABSTRACT: Premise of research. The most important diversity hot spot of genus Quercus (Fagaceae) in America is situated in southern Mexico. From this area down to the Colombian Andes, oak species diversity decreases considerably, but the pattern of species distribution and turnover has not been analyzed. This study aimed at determining geographical patterns of species turnover, species distribution, and endemism for Neotropical Quercus species. Methodology. Occurrence records for 58 oak species belonging to the Quercus and Lobatae sections were obtained. Patterns of species turnover were determined by comparing species composition among latitudinal/longitudinal units. Areas of endemism were determined using weighted networks. The potential distribution of oak species was determined using ecological niche models. Finally, a principal component analysis was used to identify changes in the oak species’ ecological niche across areas. Pivotal results. The species composition analysis indicated that the Tehuantepec Isthmus, the Nicaraguan Depression, and the Panamanian Isthmus represent species turnover points. Nine areas of endemism were recovered, distributed through mountainous ranges from Mexico to Costa Rica. Most of these areas were delimited by the species turnover points detected. Ecological niche modeling indicated that the turnover points represent areas with low climatic suitability for most oak species and represent discontinuities in the distribution of Quercus. Niche comparisons suggest niche differentiation among species distributed in different areas of endemism or on opposite sides of turnover points. Conclusions. The results indicate that the Tehuantepec Isthmus, the Nicaraguan Depression, and the Panamanian Isthmus have acted as important barriers to the dispersal of oak species, influencing species diversity, biogeographic patterns, and niche divergence.
    International Journal of Plant Sciences 02/2015; 176(3). DOI:10.1086/679904 · 1.69 Impact Factor
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    ABSTRACT: Florestina is shown to consist of six annual species occurring mostly in arid and semiarid regions of Mexico. Florestina species are morphologically similar and consequently phylogenetic relationships within the genus are poorly understood. We present a phylogenetic study based on morphological characters, DNA sequences of nuclear non-coding spacers (ETS and ITS) and chloroplast non-coding spacers (rpl32-trnL and trnC-petN). The ETS and ITS spacer-based phylogenies allowed several well-supported conclusions: (1) the genus Florestina is monophyletic and Palafoxia is its closest relative; (2) Florestina latifolia and F. platyphylla form a strongly supported clade; (3) four taxa that are morphologically very similar, F. liebmannii, F. pedata, F. simplicifolia, and F. tripteris, are phylogenetically closely related and based on the sequence data we suggest that these should be recognized as only two species, one comprising F. pedata and F. simplicifolia, which shows wide morphological variation throughout its distributional range; and the other comprising F. liebmannii and F. tripteris; (4) F. lobata and F. purpurea are species very distinct from the remainder of the species in Florestina. Our phylogenetic analyses suggest that hybridization and introgression may be involved in the evolutionary history of Florestina.
    Plant Systematics and Evolution 01/2015; DOI:10.1007/s00606-015-1220-3 · 1.15 Impact Factor
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    11/2014; 2(11). DOI:10.3732/apps.1400079
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    ABSTRACT: Question: Along an altitudinal gradient of 2000 min a semi-tropicalmountain, we explored the relation between tree specific diversity and community functional composition by studying variations in tree allometry, stem and leaf functional traits, and their relationship with temperature and precipitation. Location: Tequila Volcano, Jalisco,Mexico (20°48′ N, 103°51′ W). Methods: We surveyed tree specific diversity, five forest structural parameters and six functional traits in ten horizontal transects (50–75 m in length) located every 200 malong a 2000-mgradient (from800 to 2800 ma.s.l.).We calculated alpha and beta diversity, and quantified the community-weighted means for wood and bark density, Huber value (sapwood to leaf area ratio), leaf area, leaf dry mass content and leaf mass per unit area. The patterns of association were explored using Pearson correlations, and summarized using PCA. Results: Alpha diversity was independent of altitude, and species turnover was almost complete between consecutive transects. Altitude (and its associated abiotic factors, temperature and precipitation) were highly correlated with functional traits. Maximum tree height, total basal area and the communityweighted mean values for leaf mass per unit area, leaf drymass content, and the Huber values were positively correlated with altitude, and the opposite was found for the number of basal stems. Stem and leaf trait values were correlated along the altitudinal gradient. Conclusions: Altitude imposes environmental filters at the community scale that determine a high species replacement. Stem and leaf traits were correlated along the gradient; trees at higher altitudes were tallerwith a single stem, higher density of wood and bark, and leaves with higher leaf mass per area and dry mass content than in the low-altitude sites. These results suggest the consistency of a fast–slow acquisitive trade-off across environments, tending to promote slow acquisition and high longevity at higher altitudes.
    Journal of Vegetation Science 10/2014; 25(4). DOI:10.1111/jvs.12158 · 3.37 Impact Factor
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    ABSTRACT: Frequently, female plants allocate more resources to reproductive structures and defense-related secondary compounds in comparison with male plants that invest more resources to growth, reflecting trade-offs between reproduction, growth and defense. Therefore, differences in herbivory can be expected between genders. In this study, over two years, we analyzed the differences in plant chemical defense, nutritional quality, plant size and herbivory between genders in the dioecious tree, Spondias purpurea in a Mexican tropical dry forest. We estimated the total leaf area and the area consumed by folivory using a digital image of each leaf. The nutritional quality was estimated as water content, and the concentration of chlorophyll and total nonstructural carbohydrates. The secondary metabolites analyzed were total content of soluble phenolics, flavonoids, protein precipitation capacity of tannins, gallotannins, soluble proanthocyanidins, hydrolyzable tannins and ellagitannins. Our results differ from most of studies that analyze the differential herbivory patterns in dioecious plants. We found that female trees had higher levels of herbivory than male trees of S. purpurea. In the same way, female trees showed higher size and nutritional quality than males, while chemical defense was higher in male trees. The higher percentage of folivory in female trees of S. purpurea is associated with greater nutritional quality and lower chemical defenses. Our results show that male-biased herbivory might not be universal in dioecious species. Therefore, studies of fitness components affected by herbivory are necessary to understand the evolution of dioecy and the importance of herbivores as selective agents on breeding system features.
    Arthropod-Plant Interactions 08/2014; 8(4). DOI:10.1007/s11829-014-9314-3 · 1.18 Impact Factor
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    ABSTRACT: In the last two centuries, the development of human civilization has transformed large natural areas into anthropogenic landscapes, making habitat fragmentation a pervasive feature of modern landscapes. In animal populations, habitat frag-mentation may alter their genetic diversity and structure due to limited gene flow and dispersion and reduced effective population sizes, potentially leading to genetic drift in small habitat patches. We tested the hypothesis that habitat frag-mentation affects genetic diversity of tetrapod populations through a meta-analysis. We also examined certain life history traits of species and particular external landscape factors that may determine the magnitude of genetic erosion observed in fragmented habitats. Our results showed that habitat fragmentation reduces overall genetic diversity of tetrapod populations. Stronger negative frag-mentation effects were detected for amphibians, birds and mammals. Within each taxonomic group, species with large body size were more strongly affected by fragmentation. Particularly within mammals, we found that less vagile species with short generation times represent the most susceptible tetrapod group to lose genetic diversity in fragmented habitats. As external drivers, we found a nonsig-nificant trend of lower fragmentation effects in study systems of less than 50 years and stronger effects in older (>100 years) fragmented systems. As expected, the extent of habitat loss was also important in determining the magnitude of genetic erosion in tetrapods. Extreme habitat loss showed stronger negative effects on genetic diversity irrespective of taxonomic groups. The information gathered in this review also highlights research bias and gaps in the literature.
    Animal Conservation 07/2014; 18(3). DOI:10.1111/acv.12165 · 2.52 Impact Factor
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    ABSTRACT: The role of plant polyphenols as defenses against insect herbivores is controversial. We combined correlative field studies across three geographic regions (Northern Mexico, Southern Mexico, and Costa Rica) with induction experiments under controlled conditions to search for candidate compounds that might play a defensive role in the foliage of the tropical oak, Quercus oleoides. We quantified leaf damage caused by four herbivore guilds (chewers, skeletonizers, leaf miners, and gall forming insects) and analyzed the content of 18 polyphenols (including hydrolyzable tannins, flavan-3-ols, and flavonol glycosides) in the same set of leaves using high performance liquid chromatography and mass spectrometry. Foliar damage ranged from two to eight percent per region, and nearly 90% of all the damage was caused by chewing herbivores. Damage due to chewing herbivores was positively correlated with acutissimin B, catechin, and catechin dimer, and damage by mining herbivores was positively correlated with mongolinin A. By contrast, gall presence was negatively correlated with vescalagin and acutissimin B. By using redundancy analysis, we searched for the combinations of polyphenols that were associated to natural herbivory: the combination of mongolinin A and acutissimin B had the highest association to herbivory. In a common garden experiment with oak saplings, artificial damage increased the content of acutissimin B, mongolinin A, and vescalagin, whereas the content of catechin decreased. Specific polyphenols, either individually or in combination, rather than total polyphenols, were associated with standing leaf damage in this tropical oak. Future studies aimed at understanding the ecological role of polyphenols can use similar correlative studies to identify candidate compounds that could be used individually and in biologically meaningful combinations in tests with herbivores and pathogens.
    Journal of Chemical Ecology 05/2014; 40(5). DOI:10.1007/s10886-014-0431-3 · 2.24 Impact Factor
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    ABSTRACT: The repeated use of sleeping sites by frugivorous vertebrates promotes the deposition and aggregation of copious amounts of seeds in these sites. This spatially contagious pattern of seed deposition has key implications for seed dispersal, particularly because such patterns can persist through recruitment. Assessing the seed rain patterns in sleeping sites thus represents a fundamental step in understanding the spatial structure and regeneration of plant assemblages. We evaluated the seed rain produced by spider monkeys (Ateles geoffroyi) in latrines located beneath 60 sleeping trees in two continuous forest sites (CFS) and three forest fragments (FF) in the Lacandona rainforest, Mexico. We tested for differences among latrines, among sites, and between forest conditions in the abundance, diversity (α-, β- and, γ-components) and evenness of seed assemblages. We recorded 45,919 seeds ≥5 mm (in length) from 68 species. The abundance of seeds was 1.7 times higher in FF than in CFS, particularly because of the dominance of a few plant species. As a consequence, community evenness tended to be lower within FF. β-diversity of common and dominant species was two times greater among FF than between CFS. Although mean α-diversity per latrine did not differ among sites, the greater β-diversity among latrines in CFS increased γ-diversity in these sites, particularly when considering common and dominant species. Our results support the hypothesis that fruit scarcity in FF can 'force' spider monkeys to deplete the available fruit patches more intensively than in CFS. This feeding strategy can limit the effectiveness of spider monkeys as seed dispersers in FF, because (i) it can limit the number of seed dispersers visiting such fruit patches; (ii) it increases seed dispersal limitation; and (iii) it can contribute to the floristic homogenization (i.e., reduced β-diversity among latrines) in fragmented landscapes.
    PLoS ONE 02/2014; 9(2):e89346. DOI:10.1371/journal.pone.0089346 · 3.53 Impact Factor
  • Revista Mexicana de Ciencias Pecuarias 12/2013; 4(4):417-434. · 0.23 Impact Factor
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    ABSTRACT: The nesting colony of green sea turtles (Chelonia mydas) at Guanahacabibes Peninsula Biosphere Reserve and National Park is one of the largest in the Cuban archipelago; however, little information about its nesting ecology is available. Temporal and spatial variation in nesting and reproductive success as well as morphometric characteristics of gravid females were used to ecologically characterize this colony. Nine beaches of the Southernmost coast of Guanahacabibes Peninsula were monitored for 14 years (1998-2012) to determine green turtle nesting activity, from May to September (peak nesting season in this area). Beach dimensions were measured to determine nest density using the length and the area. Afterward the beaches were divided in two categories, index and secondary. Females were measured and tagged to compare new tagged females (823) with returning tagged females (140). Remigration interval was also determined. Temporal variation was identified as the annual number of nesting emergences and oviposits per female, with apparent peaks in reproductive activity on a biennial cycle in the first six years followed by periods of annual increase in nest number (2003-2008) and periods of decreasing number of nests (2010-2012). We also found intra-seasonal variation with the highest nesting activity in July, particularly in the second half of the month. The peak emergence time was 22:00-02:00 hr. In terms of spatial variation, smaller beaches had the highest nest density and nesting was more frequent 6-9m from the high tide line, where hatchling production was maximized although hatchling success was high on average, above 80%. Morphometric analysis of females was made and newly tagged turtles were smaller on average than remigrants. Our results are only a first attempt at characterizing Guanahacabibes' populations but have great value for establishing conservation priorities within the context of national management plans, and for efficient monitoring and protection of nesting beaches.
    Revista de biologia tropical 12/2013; 61(4):1935-45. DOI:10.15517/rbt.v61i4.12869 · 0.61 Impact Factor
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    ABSTRACT: Forest structure and composition have been used to assess the habitat characteristics that determine bird distributions. The patterns of distribution have been shaped by historical and ecological factors that play different roles at both temporal and spatial scales. The objectives of this research were to characterize the habitat of the endangered Military Macaw (Ara militaris) and evaluate the potential distribution of this species based on trends of land use changes in Mexico. We characterized the community structure and floristic composition of 8 forests that are currently used by the Military Macaw for breeding and feeding and compared the results with 6 similar forests characterized in other studies but without historical records of the presence of the Military Macaw. The Military Macaw preferred sites with high diversity of plant species dominated by trees from 4 to 15 m in height and from 5 to 90 cm in diameter at breast height. We identified 236 plant species in the 8 forests with 20 species (8.4%) used for nesting and feeding by the Military Macaw. The floristic composition is important for the presence of the Military Macaw because there were significant differences between forests with and without its presence. The potential area of distribution of the Military Macaw had decreased by 32% and the remnant areas are included in only 8 National Protected Areas. The protected areas of natural forests should be increased to preserve the sites of potential distribution and consequently the habitat of the Military Macaw in Mexico.
    REVISTA MEXICANA DE BIODIVERSIDAD 12/2013; 84(4):1200-1215. DOI:10.7550/rmb.34953 · 0.45 Impact Factor
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    ABSTRACT: • Premise of study: Anthropogenic fragmentation is an ongoing process in many forested areas that may create loss of connectivity among tree populations and constitutes a serious threat to ecological and genetic processes. We tested the central hypothesis that seed dispersal mitigates the impact of fragmentation by comparing connectivity and genetic diversity of adult vs. seedling populations in recently fragmented populations of the Mexican red oak Quercus castanea.• Methods: Adult individuals, established before fragmentation, and seedlings, established after fragmentation, were sampled at 33 forest fragments of variable size (0.2 to 294 ha) within the Cuitzeo basin, Michoacán state, and genotyped using seven highly polymorphic chloroplast microsatellite markers (cpSSRs). To test whether seed dispersal retains connectivity among fragmented populations, we compared genetic diversity and connectivity networks between adults and progeny and determined the effect of fragment size on these values.• Key results: Seventy haplotypes were identified, 63 in the adults and 60 in the seedlings, with average within-population diversity (hS) values of 0.624 in the adults and 0.630 in the seedlings. A positive correlation of genetic diversity values with fragment size was found in the seedling populations but not in the adult populations. The network connectivity analysis revealed lower connectivity among seedling populations than among adults. The number of connections (edges) as well as other network properties, such as betweenness centrality, node degree and closeness, were significantly lower in the seedlings network.• Conclusions: Habitat fragmentation in this landscape is disrupting seed-dispersal-mediated genetic connectivity among extant populations.
    American Journal of Botany 08/2013; 100(8). DOI:10.3732/ajb.1200396 · 2.46 Impact Factor
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    ABSTRACT: The evolution of plant defense traits has traditionally been explained trough the “coevolutionary arms race” between plants and herbivores. According to this, specialist herbivores have evolved to cope effectively with the defensive traits of their host plants and may even use them as a cue for host location. We analyzed the geographic association between leaf trichomes, two tropane alkaloids (putative resistance traits), and leaf damage by herbivores in 28 populations of Datura stramonium in central Mexico. Since the specialist leaf beetles Epitrix parvula and Lema trilineata are the main herbivores of D. stramonium in central Mexico, we predicted a positive association between plant defense and leaf damage across populations. Also, if physical environmental conditions (temperature or precipitation) constrain the expression of plant defense, then the geographic variation in leaf damage should be explained partially by the interaction between defensive traits and environmental factors. Furthermore, we studied the temporal and spatial variation in leaf trichome density and leaf damage in five selected populations of D. stramonium sampled in two periods (1997 vs. 2007). We found a positive association between leaf trichomes density and atropine concentration with leaf damage across populations. The interaction between defensive traits and water availability in each locality had a significant effect on the geographic variation in leaf damage. Differences among populations in leaf trichome density are maintained over time. Our results indicate that local plant–herbivore interaction plays an important role in shaping the geographic and temporal variation in plant defense in D. stramonium.
    07/2013; 28(4):1-10. DOI:10.1007/s11284-013-1059-4
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    ABSTRACT: Mexico is the main center of diversity of the genus Quercus in the Western Hemisphere. Despite recent advances in the knowledge of Mexican oaks, a degree of taxonomic confusion still remains, mainly within particular species complexes. In this study, scanning electron microscopy was used to describe micromorphological foliar structures (trichomes, epicuticular waxes and stomata) from the abaxial and adaxial leaf surfaces of Mexican oak species, with the main goal of assessing the taxonomical utility of these characters. In total, 27 species belonging to sections Quercus (white oaks) and Lobatae (red/black oaks) were examined, particularly focusing on several groups of closely related species with problematic taxonomic delimitation and on species that are known to hybridize. Several trichome types were observed, including both glandular (simple and bulbous) and eglandular (solitary, multiradiate, stellate, fused stellate and fasciculate stipitate). Epicuticular waxes were structured as films, grooved films, crusts, granules, platelets and platelets arranged in rosettes. Stomata were elliptical and raised above or leveled with the foliar surface. Among the three types of structures examined, trichomes appeared to be the most useful for taxonomical purposes, followed by epicuticular waxes. All species had different combinations of character states for these micromorphological structures, which permitted the elaboration of keys to identify species within the problematic groups.
    Acta botánica Mexicana 07/2013; · 0.63 Impact Factor
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    ABSTRACT: We present a cost-effective statistical approach that integrates satellite imagery, environmental variables and ground inventory data to map the spatial distribution of aboveground woody biomass suitable for charcoal making. The study was conducted in the Cuitzeo basin located in central Mexico, where charcoal is produced from oak forests covering approximately 10% of the total area (4033 km2). Diameters of trees and sprouts in 78 plots of 0.2 ha each was measured. Allometric equations previously developed locally that only require tree diameters were employed to estimate the amount of woody biomass suitable for charcoal making i.e. the amount of wood that is loaded into the kilns. The performance of two statistical techniques for the interpolation of field data was assessed by cross-validation; these techniques were linear regression and regression-kriging, the second taking into account the spatial autocorrelation of data. Spectral bands, vegetation indices, texture measurements and variables derived from a Digital Elevation Model were examined as explanatory variables. Accounting for spatial autocorrelation (regression-kriging) improved the model's R2 from 0.61 to 0.69, representing a relative error reduction of 11.3% (from 11.01 to 9.77 t ha− 1 of wood suitable for charcoal). The available stock was compared to current estimates of charcoal demand in the Cuitzeo basin and insights were given on how this information can be used to estimate the annual sustainable production potential of oak in order to account for supply–demand balances.
    Energy for Sustainable Development 04/2013; 17(2):177–188. DOI:10.1016/j.esd.2012.10.007 · 2.36 Impact Factor
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    ABSTRACT: Lilaea scilloides (Juncaginaceae) is an aquatic species inhabiting temporary wetlands. It is an annual herbaceous emergent plant distributed from Canada to Argentina. This species reproduces both sexually and asexually, and is wind-pollinated. Flowers are highly heteromorphic with 5 different types of flowers. We hypothesized that, because of its pollination syndrome, wide distribution and local abundance, the species would have high genetic diversity, low endogamy, low genetic differentiation, and high gene flow. The objectives of this study were to determine the genetic diversity and structure of L. scilloides and compare with species with similar ecological and life history traits. We analyzed 40 individuals from 12 populations using isozyme electrophoresis in starch gels. The results showed a low within population genetic diversity (A= 1.77, Ae= 1.15, P= 56.6, Ho= 0.064 and He= 0.103), a high endogamy index (FIS= 0.288), low genetic differentiation among populations (FST= 0.077), and high gene flow (Nm= 4.42). We also found evidence of a high degree of clonal propagation in the species. These results indicate that asexual reproduction is extremely important for the species, as well as the possibility that Lilaea scilloides has hydrophilous pollination, which has not been previously reported.
    REVISTA MEXICANA DE BIODIVERSIDAD 03/2013; 84(1):240-248. DOI:10.7550/rmb.18898 · 0.45 Impact Factor
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    ABSTRACT: Abstract: In tropical latitudes, the analysis of leaf phenology in tree species of lineages with temperate origin can help better understanding the potential effects of climate change on these forests. Over three years (2008–2010), we recorded the timing of bud burst (BB), leaf unfolding (LU), and leaf spreading (LS) and their relation to temperature, precipitation, and soil water potential in two deciduous oak species (Quercus magnoliifolia Née and Quercus resinosa Liebm.) along an altitudinal gradient at the Tequila Volcano, central Mexico. Quercus magnoliifolia was monitored at three altitudes, 1450, 1667, and 1787 m, and Q. resinosa was monitored at 1787, 2055, and 2110 m. The onset of BB, LU, and LS occurred earlier at lower elevations with higher temperature in Q. magnoliifolia, but in Q. resinosa only the onset of BB occurred later at lower elevations with higher temperature. BB, LU, and LS were not correlated with rainfall and soil water potential in the two species. The total duration time of leaf development was not significantly correlated with rainfall in Q. magnoliifolia, but a significant negative correlation with rainfall was found in Q. resinosa. Results indicated that leaf phenology of the two examined oak species exhibited contrasting responses to temperature and precipitation.
    Canadian Journal of Forest Research 02/2013; 43(2):208-213. DOI:10.1139/cjfr-2012-0406 · 1.66 Impact Factor