Sebastian Block | University of Adelaide (original) (raw)

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Research paper thumbnail of Where to Dig for Fossils: Combining Climate- Envelope, Taphonomy and Discovery Models

Fossils represent invaluable data to reconstruct the past history of life, yet fossil-rich sites ... more Fossils represent invaluable data to reconstruct the past history of life, yet fossil-rich sites are often rare and difficult to find. The traditional fossil-hunting approach focuses on small areas and has not yet taken advantage of modelling techniques commonly used in ecology to account for an organism's past distributions. We propose a new method to assist finding fossils at continental scales based on modelling the past distribution of species, the geological suitability of fossil preservation and the likelihood of fossil discovery in the field, and apply it to several genera of Australian megafauna that went extinct in the Late Quaternary. Our models predicted higher fossil potentials for independent sites than for randomly selected locations (mean Kolmogorov-Smirnov statistic = 0.66). We demonstrate the utility of accounting for the distribution history of fossil taxa when trying to find the most suitable areas to look for fossils. For some genera, the probability of finding fossils based on simple climate-envelope models was higher than the probability based on models incorporating current conditions associated with fossil preservation and discovery as predictors. However , combining the outputs from climate-envelope, preservation, and discovery models resulted in the most accurate predictions of potential fossil sites at a continental scale. We proposed potential areas to discover new fossils of Diprotodon, Zygomaturus, Protemno-don, Thylacoleo, and Genyornis, and provide guidelines on how to apply our approach to assist fossil hunting in other continents and geological settings.

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Research paper thumbnail of Structure and diversity of oak forests in the El Tepozteco National Park (Morelos, Mexico)

Quercus (oak) is among the most speciose and widespread genera occurring in Mexico; paradoxically... more Quercus (oak) is among the most speciose and widespread genera occurring in Mexico; paradoxically, the ecological knowledge about Mexican oak forests is meager. Here we describe the floristic composition, diversity, and structure of the terrestrial component of the oak forests of the El Tepozteco National Park (TNP), Central Mexico, and relate their floristic and structural heterogeneity to the geomorphological complexity of the park. We randomly distributed sixty 100-m2 plots among six geomorphological units: the lava fields of the Chichinautzin, Suchiooc, Otates (upper and lower) and Oclayuca volcanoes, and the El Tepozteco Range. Vegetation structure and diversity were described by geomorphological unit and for the oak forest as a whole for canopy (DBH ≥ 2.5 cm) and understory plants. We report 324 vascular plant species recorded in the plots, plus 17 species collected outside the plots (a total of 341 species, 208 genera and 88 families). The family with more species was Asteraceae (57) and the most speciose genus was Salvia (10). Geomorphological units differed in mean species richness per plot (12.0-33.5 species), absolute richness (60-149 species), and species’ structural contributions; structural differences were also observed, but were not always significant. Quercus rugosa was dominant in Chichinautzin, Suchiooc, and upper Otates; Styrax ramirezii in lower Otates and Oclayuca, and Quercus castanea and Q. obtusata shared dominance in El Tepozteco Range (the unit with the largest overall richness and oak species diversity). The structure and composition of TNP oak forests are highly variable, apparently due to the region’s complex geological past. This heterogeneity should guide the conservation and restoration of these forests.

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Research paper thumbnail of Floristic and structural heterogeneity of the oak forests of El Tepozteco national park (Mexico)

Heterogeneidad florística y estructural de los encinares del Parque Nacional El Tepozteco (México), Feb 2013

The environmental heterogeneity of a natural protected area is major driver of the spatial distri... more The environmental heterogeneity of a natural protected area is major driver of the spatial distribution of biodiversity within its territory. The goal of this study was to determine the effect of
geomorphological heterogeneity on the spatial variation of oak forest diversity, floristic composition and structure at the El Tepozteco National Park (Morelos, Mexico). Floristic composition and vegetation structural attributes were recorded in 10 sampling plots randomly distributed in each one of six geomorphological units occurring in the park. In total, 343 plant species were identified, with plant richness by unit varying from 60 species in the oldest lava field to 151 in the El Tepozteco mountain range. Estimated richness with Chao 2 algorithm for the entire oak forest was 448.2 species, a larger value than those calculated for geomorphological units separately (94.3 to 284.6 species). Vegetation structure also varied greatly between units. The
largest basal area values (60.5 m2/ha) and vegetation height (22.8 m) corresponded to the oldest lava field, while the smallest (19.6 m2/ha and 9.0 m, respectively) were recorded in the most recent one. A canonical correspondence analysis showed that geomorphological heterogeneity better explains the variation of understory diversity than that of canopy. These results show that the park’s geomorphological heterogeneity is partially responsible for the regional high biodiversity. Likewise, it was proved that structure, floristic composition and plant diversity vary greatly between the various park’s oak forests, which may help identify priority areas upon which to focus future conservation efforts in this natural protected area.

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Research paper thumbnail of Where to Dig for Fossils: Combining Climate- Envelope, Taphonomy and Discovery Models

Fossils represent invaluable data to reconstruct the past history of life, yet fossil-rich sites ... more Fossils represent invaluable data to reconstruct the past history of life, yet fossil-rich sites are often rare and difficult to find. The traditional fossil-hunting approach focuses on small areas and has not yet taken advantage of modelling techniques commonly used in ecology to account for an organism's past distributions. We propose a new method to assist finding fossils at continental scales based on modelling the past distribution of species, the geological suitability of fossil preservation and the likelihood of fossil discovery in the field, and apply it to several genera of Australian megafauna that went extinct in the Late Quaternary. Our models predicted higher fossil potentials for independent sites than for randomly selected locations (mean Kolmogorov-Smirnov statistic = 0.66). We demonstrate the utility of accounting for the distribution history of fossil taxa when trying to find the most suitable areas to look for fossils. For some genera, the probability of finding fossils based on simple climate-envelope models was higher than the probability based on models incorporating current conditions associated with fossil preservation and discovery as predictors. However , combining the outputs from climate-envelope, preservation, and discovery models resulted in the most accurate predictions of potential fossil sites at a continental scale. We proposed potential areas to discover new fossils of Diprotodon, Zygomaturus, Protemno-don, Thylacoleo, and Genyornis, and provide guidelines on how to apply our approach to assist fossil hunting in other continents and geological settings.

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Research paper thumbnail of Structure and diversity of oak forests in the El Tepozteco National Park (Morelos, Mexico)

Quercus (oak) is among the most speciose and widespread genera occurring in Mexico; paradoxically... more Quercus (oak) is among the most speciose and widespread genera occurring in Mexico; paradoxically, the ecological knowledge about Mexican oak forests is meager. Here we describe the floristic composition, diversity, and structure of the terrestrial component of the oak forests of the El Tepozteco National Park (TNP), Central Mexico, and relate their floristic and structural heterogeneity to the geomorphological complexity of the park. We randomly distributed sixty 100-m2 plots among six geomorphological units: the lava fields of the Chichinautzin, Suchiooc, Otates (upper and lower) and Oclayuca volcanoes, and the El Tepozteco Range. Vegetation structure and diversity were described by geomorphological unit and for the oak forest as a whole for canopy (DBH ≥ 2.5 cm) and understory plants. We report 324 vascular plant species recorded in the plots, plus 17 species collected outside the plots (a total of 341 species, 208 genera and 88 families). The family with more species was Asteraceae (57) and the most speciose genus was Salvia (10). Geomorphological units differed in mean species richness per plot (12.0-33.5 species), absolute richness (60-149 species), and species’ structural contributions; structural differences were also observed, but were not always significant. Quercus rugosa was dominant in Chichinautzin, Suchiooc, and upper Otates; Styrax ramirezii in lower Otates and Oclayuca, and Quercus castanea and Q. obtusata shared dominance in El Tepozteco Range (the unit with the largest overall richness and oak species diversity). The structure and composition of TNP oak forests are highly variable, apparently due to the region’s complex geological past. This heterogeneity should guide the conservation and restoration of these forests.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Floristic and structural heterogeneity of the oak forests of El Tepozteco national park (Mexico)

Heterogeneidad florística y estructural de los encinares del Parque Nacional El Tepozteco (México), Feb 2013

The environmental heterogeneity of a natural protected area is major driver of the spatial distri... more The environmental heterogeneity of a natural protected area is major driver of the spatial distribution of biodiversity within its territory. The goal of this study was to determine the effect of
geomorphological heterogeneity on the spatial variation of oak forest diversity, floristic composition and structure at the El Tepozteco National Park (Morelos, Mexico). Floristic composition and vegetation structural attributes were recorded in 10 sampling plots randomly distributed in each one of six geomorphological units occurring in the park. In total, 343 plant species were identified, with plant richness by unit varying from 60 species in the oldest lava field to 151 in the El Tepozteco mountain range. Estimated richness with Chao 2 algorithm for the entire oak forest was 448.2 species, a larger value than those calculated for geomorphological units separately (94.3 to 284.6 species). Vegetation structure also varied greatly between units. The
largest basal area values (60.5 m2/ha) and vegetation height (22.8 m) corresponded to the oldest lava field, while the smallest (19.6 m2/ha and 9.0 m, respectively) were recorded in the most recent one. A canonical correspondence analysis showed that geomorphological heterogeneity better explains the variation of understory diversity than that of canopy. These results show that the park’s geomorphological heterogeneity is partially responsible for the regional high biodiversity. Likewise, it was proved that structure, floristic composition and plant diversity vary greatly between the various park’s oak forests, which may help identify priority areas upon which to focus future conservation efforts in this natural protected area.

Bookmarks Related papers MentionsView impact