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  • 1
    Electronic Resource
    Electronic Resource
    Affinity among mountain ranges in Megamexico: A phytogeographical scenario (1994)
    Springer
    Plant ecology 115 (1994), S. 1-9 
    Details
    ISSN: 1573-5052
    Keywords: Phytogeography ; Megamexico ; High mountain vegetation ; Multivariate analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The concept of Megamexico as a phytogeographic unit has been introduced by Rzedowski (1991) on the basis of distribution patterns of genera. Until now precise information on the resemblance between plant communities in the proposed Megamexico was scarce. This phytosociological study documents the affinities between plant communities within Megamexico, based on studies from mountain ranges in Mexico (Sierra Chichinautzin, Sierra Nevada) and Guatemalan mountain ranges (Sierra de los Cuchumatanes, Cadena Volcánica). Data, collected in the style of Braun-Blanquet during extensive fieldwork, were pooled into a single data set, and analyzed by using (1) TWINSPAN, for plant community classification, (2) ordination (DCA), (3) alpha log series biodiversity-index to measure intergroup diversity, and (4) information on the altitudinal distribution of the vegetation belts. Classification showed that four communities were common to the two groups of mountain ranges, namely, alpine bunchgrass-land, pine forest, fir forest and mixed forest. Along the altitudinal gradient Mexican communities are distributed 200 m higher than their Guatemalan equivalents. This appears to be an illustration of the ‘Massenerhebungseffekt’. DCA showed that the first axis represents a set of minor differences of closely related ecological factors (e.g., temperature, precipitation) and the second a humidity gradient. The biodiversity index showed that the Mexican mixed forest was significantly more diverse than the Guatemalan mixed forest. From the present results, ecological conditions among mountain ranges in Megamexico differed significantly. To conclude, phytogeographical units in Megamexico can better be defined on basis of both historical and ecological characteristics of the communities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00119381
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  • 2
    Electronic Resource
    Electronic Resource
    High elevation coniferous vegetation of Guatemala (1995)
    Springer
    Plant ecology 116 (1995), S. 7-23 
    Details
    ISSN: 1573-5052
    Keywords: Altitudinal distribution ; Ecology ; Guatemala ; Pine communities ; Phytosociology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A phytosociological study of the juniper (locally called huito), pine (locally called sacch), pine-alder and fir forests of the Sierra de los Cuchumatanes and Cadena Volcánica in Guatemala was carried out. The Zürich-Montpellier approach was followed. In total 119 relevés were sampled and the data were organised in phytosociological tables to distinguish vegetation clusters. TWINSPAN was used to evaluate major differences among plant communities. Seven zonal plant communities were distinguished and described, namely: (1)Relbunium microphyllum-Agrostis tolucensis, (2)Werneria nubigena-Agrostis exserta, (3)Lachemilla vulcanica-Pinus hartwegii, (4)Holodiscus argenteus-Pinus hartwegii, (5)Hypnum cypressiforme-Juniperus standleyi, (6)Agave hurteri-Alnus firmifolia and (7)Sabazia pinetorum-Abies guatemalensis. This paper provides a thorough floristic characterisation of each community and outlines the major anthropogenic activities. To conclude, ecologic and floristic (dis)similarities between plant communities of the study area and those of Central Mexico, like the different altitudinal distribution of fir forests and the establishment of mid-successional communities such as theAgave hurteri-Alnus firmifolia were discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00045273
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  • 3
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    Mangrove history during middle- and late-Holocene in Pacific south-eastern Mexico (2015)
    Sage
    In: Holocene
    Details
    Publication Date: 2015-03-03
    Description: A paleoecological analysis of a 6-m-long sedimentary sequence from the La Encrucijada Biosphere Reserve (RBLE) from southern Pacific Mexico provides detailed information about past vegetation changes between ~6200 and 700 cal. yr BP. Highest percentages of mangrove pollen in pollen zone I (from ~6200 to 5400 cal. yr BP) suggest moister and warmer conditions than at present related with global rates of sea-level rise and northward position of the Intertropical Convergence Zone (ITCZ), suppressing El Niño-Southern Oscillation (ENSO) events. Drier conditions and decreasing rates of sea-level rise at ~5400–4500 cal. yr BP are evidenced in pollen zone II by the lowest percentages of mangrove pollen and highest presence of disturbance pollen. Recovery of mangroves and tropical forests occurred from ~4500 cal. yr BP, suggesting moister conditions. Agricultural activities are recorded around ~4900, 4700 and 2400 cal. yr BP, although human occupation was scarce in the mangrove area. ENSO variability correlates to mangrove pollen variation between 3600 and 2400 cal. yr BP. A protracted drought is observed at ~1300–700 cal. yr BP characterized by proportions in montane forest pollen and may be related with southern oscillation of the ITCZ and the Classical Mayan Demise.
    Print ISSN: 0959-6836
    Electronic ISSN: 1477-0911
    Topics: Geography , Geosciences
    Published by Sage
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  • 4
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    Recent Pollen Spectra of Highland Guatemala (1995)
    Wiley
    Details
    Publication Date: 1995-11-01
    Print ISSN: 0305-0270
    Electronic ISSN: 1365-2699
    Topics: Biology , Geography
    Published by Wiley
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  • 5
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    Pollen-based biome reconstructions for Latin America at 0, 6000 and 18 000 radiocarbon years (2009)
    Copernicus
    Details
    Publication Date: 2009-02-10
    Description: The biomisation method is used to reconstruct Latin American vegetation at 6000±500 and 18 000±1000 radiocarbon years before present (14C yr BP) from pollen data. Tests using modern pollen data from 381 samples derived from 287 locations broadly reproduce potential natural vegetation. The strong temperature gradient associated with the Andes is recorded by a transition from high altitude cool grass/shrubland and cool mixed forest to mid-altitude cool temperate rain forest, to tropical dry, seasonal and rain forest at low altitudes. Reconstructed biomes from a number of sites do not match the potential vegetation due to local factors such as human impact, methodological artefacts and mechanisms of pollen representivity of the parent vegetation. At 6000±500 14C yr BP 255 samples are analysed from 127 sites. Differences between the modern and the 6000±500 14C yr BP reconstruction are comparatively small. Patterns of change relative to the modern reconstruction are mainly to biomes characteristic of drier climate in the north of the region with a slight more mesic shift in the south. Cool temperate rain forest remains dominant in western South America. In northwestern South America a number of sites record transitions from tropical seasonal forest to tropical dry forest and tropical rain forest to tropical seasonal forest. Sites in Central America also show a change in biome assignment to more mesic vegetation, indicative of greater plant available moisture, e.g. on the Yucatán peninsula sites record warm evergreen forest, replacing tropical dry forest and warm mixed forest presently recorded. At 18 000±1000 14C yr BP 61 samples from 34 sites record vegetation that reflects a generally cool and dry environment. Cool grass/shrubland prevalent in southeast Brazil, Amazonian sites record tropical dry forest, warm temperate rain forest and tropical seasonal forest. Southernmost South America is dominated by cool grass/shrubland, a single site retains cool temperate rain forest indicating that forest was present at some locations at the LGM. Some sites in Central México and lowland Colombia remain unchanged in their biome assignments, although the affinities that these sites have to different biomes do change between 18 000±1000 14C yr BP and present. The "unresponsive" nature of these sites results from their location and the impact of local edaphic influence.
    Print ISSN: 1814-9340
    Electronic ISSN: 1814-9359
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 6
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    Hurricane Gilbert and structural changes in a tropical forest in south‐eastern Mexico (1999)
    Wiley
    Details
    Publication Date: 1999-01-01
    Print ISSN: 1466-822X
    Electronic ISSN: 1466-8238
    Topics: Biology , Geography
    Published by Wiley
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  • 7
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    Identifying drivers of forest resilience in long-term records from the Neotropics (2020)
    The Royal Society
    Details
    Publication Date: 2020-04-01
    Description: Here, we use 30 long-term, high-resolution palaeoecological records from Mexico, Central and South America to address two hypotheses regarding possible drivers of resilience in tropical forests as measured in terms of recovery rates from previous disturbances. First, we hypothesize that faster recovery rates are associated with regions of higher biodiversity, as suggested by the insurance hypothesis. And second, that resilience is due to intrinsic abiotic factors that are location specific, thus regions presently displaying resilience in terms of persistence to current climatic disturbances should also show higher recovery rates in the past. To test these hypotheses, we applied a threshold approach to identify past disturbances to forests within each sequence. We then compared the recovery rates to these events with pollen richness before the event. We also compared recovery rates of each site with a measure of present resilience in the region as demonstrated by measuring global vegetation persistence to climatic perturbations using satellite imagery. Preliminary results indeed show a positive relationship between pre-disturbance taxonomic richness and faster recovery rates. However, there is less evidence to support the concept that resilience is intrinsic to a region; patterns of resilience apparent in ecosystems presently are not necessarily conservative through time.
    Print ISSN: 1744-9561
    Electronic ISSN: 1744-957X
    Topics: Biology
    Published by The Royal Society
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