The Austral and Neotropical America (ANA) section of the Society for Conservation Biology include... more The Austral and Neotropical America (ANA) section of the Society for Conservation Biology includes a vast territory with some of the largest relatively pristine ecosystems in the world. With more than 573 million people, the economic growth of the region still depends strongly on natural resource exploitation and still has high rates of environmental degradation and biodiversity loss. A survey among the ANA section membership, with more than 700 members, including most of the section's prominent ecologists and conservationists, indicates that lack of capacity building for conservation, corruption, and threats such as deforestation and illegal trade of species, are among the most urgent problems that need to be addressed to improve conservation in the region. There are, however, strong universities and ecology groups taking the lead in environmental research and conservation, a most important issue to enhance the ability of the region to solve conservation and development conflicts. Retos de Conservación para la Sección América Austral y Neotropical Resumen: La sección América Austral y Neotropical (AAN) de la Sociedad para la Biología de la Conser-vación incluye un vasto territorio con unos de los ecosistemas relativamente prístinos más extensos del mundo. Con más de 573 millones de habitantes, el crecimiento económico de la región aun depende fuertemente de la explotación de recursos naturales y aún tiene altas tasas de degradación ambiental y pérdida de biodi-versidad. Un sondeo de la membresía de la sección AAN, con más de 700 miembros, incluyendo la mayoría de los ecólogos y conservacionistas más prominentes de la sección, indica que la carencia de desarrollo de capacidades para la conservación, la corrupción y amenazas como la deforestación y el comercio ilegal de especies, son algunos de los problemas que requieren ser atendidos más urgentemente para mejorar la con-servación en la región. Sin embargo, hay universidades y grupos ecológicos que están tomando el liderazgo §
Background/Question/Methods The Mexico – US border, expanding more than 3,169 km (1,969 mi), is t... more Background/Question/Methods The Mexico – US border, expanding more than 3,169 km (1,969 mi), is the most crossed border in the World. It is a vast land that harbors a high diversity of ecosystems, stretching from extremely arid lands, to temperate and subtropical forests. It maintains a high biodiversity and represents either the northern or southern limits in the distribution of many plants and animals. The border region faces very complex social and economic issues, that have been exacerbated by the increasing drug traffic from Mexico to the US, fueled by an ever growing consumption of drugs in the US, and an ever increasing drug violence in Mexico. The US government is building unilaterally a wall across most of the border that is the only huma structure in the whole planet that is becoming a continental barrier for the dispersal and movements of many plants anal animals. I here present a comprehensive review the biological characteristics of the border area, the impact of the fe...
The widespread encroachment of woody plants throughout the semi-arid grasslands in North America ... more The widespread encroachment of woody plants throughout the semi-arid grasslands in North America has largely resulted from overgrazing by domestic livestock, fire suppression, and loss of native large and small mammalian herbivores. Burrowing-herbivorous mammals, such as prairie dogs (Cynomys spp.), help control shrub encroachment through clipping of shrubs and consumption of their seedlings, but little is known about how this important ecological role interacts with and may be influenced by co-existing large herbivores, especially domestic livestock. Here, we established a long-term manipulative experiment using a 2 × 2 factorial design to assess the independent and interactive effects of black-tailed prairie dogs (Cynomys ludovicianus) and cattle (Bos taurus) on honey mesquite (Prosopis glandulosa) abundance and structure. We found that, after five years, mesquite abundance was three to five times greater in plots where prairie dogs were removed compared to plots where they occurred together or alone, respectively. While both prairie dogs and cattle reduced mesquite cover, the effect of prairie dogs on reducing mesquite abundance, cover, and height was significantly greater than that by cattle. Surprisingly, cattle grazing enhanced prairie dog abundance, which, in turn, magnified the effects of prairie dogs on mesquite shrubs. Mesquite canopy cover per hectare was three to five times greater where prairie dogs and cattle were absent compared to where they occurred together or by themselves; whereas, cumulative mesquite height was two times lower on sites where prairie dog and cattle occurred together compared to where they occurred alone or where neither occurred. Data from our experimental study demonstrate that prairie dogs and moderate grazing by cattle can suppress mesquite growth, and, when their populations are properly managed, they may interact synergistically to significantly limit mesquite encroachment in desert grasslands.
The oft-repeated claim that Earth&amp... more The oft-repeated claim that Earth's biota is entering a sixth "mass extinction" depends on clearly demonstrating that current extinction rates are far above the "background" rates prevailing between the five previous mass extinctions. Earlier estimates of extinction rates have been criticized for using assumptions that might overestimate the severity of the extinction crisis. We assess, using extremely conservative assumptions, whether human activities are causing a mass extinction. First, we use a recent estimate of a background rate of 2 mammal extinctions per 10,000 species per 100 years (that is, 2 E/MSY), which is twice as high as widely used previous estimates. We then compare this rate with the current rate of mammal and vertebrate extinctions. The latter is conservatively low because listing a species as extinct requires meeting stringent criteria. Even under our assumptions, which would tend to minimize evidence of an incipient mass extinction, the average rate of vertebrate species loss over the last century is up to 100 times higher than the background rate. Under the 2 E/MSY background rate, the number of species that have gone extinct in the last century would have taken, depending on the vertebrate taxon, between 800 and 10,000 years to disappear. These estimates reveal an exceptionally rapid loss of biodiversity over the last few centuries, indicating that a sixth mass extinction is already under way. Averting a dramatic decay of biodiversity and the subsequent loss of ecosystem services is still possible through intensified conservation efforts, but that window of opportunity is rapidly closing.
Costa Rica has one of the greatest percentages (26%) of protected land in the world. The National... more Costa Rica has one of the greatest percentages (26%) of protected land in the world. The National Protected Areas System (NPAS) of Costa Rica was established in 1976 and currently includes >190 protected areas within seven different protection categories. The effectiveness of the NPAS to represent species, populations, and areas with high species richness has not been properly evaluated. Such evaluations are fundamental to understand what is necessary to strengthen the NPAS and better protect biodiversity. We present a novel assessment of NPAS effectiveness in protecting mammal species. We compiled the geographical ranges of all terrestrial Costa Rican mammals then determined species lists for all protected areas and the estimated proportion of each species’ geographic range protected. We also classified mammal species according to their conservation status using the IUCN Red List of Threatened Species. We found almost complete representation of mammal species (98.5%) in protected areas, but low relative coverage (28.3% on average) of their geographic ranges in Costa Rica and 25% of the species were classified as underprotected according to a priori representation targets. Interestingly, many species-rich areas are not protected, and at least 43% of cells covering the entire country are not included in protected areas. Though protected areas in Costa Rica represent species richness well, strategic planning for future protected areas to improve species complementarity and range protection is necessary. Our results can help to define sites where new protected areas can have a greater impact on mammal conservation, both in terms of species richness and range protection.
The diversity of Mexican mammals is one of the largest in the World. Over the past 15-years studi... more The diversity of Mexican mammals is one of the largest in the World. Over the past 15-years studies on taxonomy, syste- matics, and distribution have modi␣ed the former mammal checklist for the country. Here we present an updated checklist that comprise 13 orders, 46 families, 201 genera, and 550 species, of which 170 are endemic to Mexico. In the checlist we include data on the distribution, biogeographic affinities, and conservation status at the National and World level. We also have included distribution maps of all the species.
... Ochoa, OL 2003. ... no Almeraya, Enrique Muñoz Ló-pez, Pablo Ortuño Sánchez, Gus-tavo Ramírez... more ... Ochoa, OL 2003. ... no Almeraya, Enrique Muñoz Ló-pez, Pablo Ortuño Sánchez, Gus-tavo Ramírez Santiago, Luis Gerar-do Ramos Cruz, Rainer Ressl, Antonio Guillermo Robles Caraza, Ramón Solano Barajas, Assefaw Tewolde Medhin, Rocío Vi llal ó n Calderón, niños y ...
... Universidad Nacional Autónoma de México. Título : Diversidad y conservación de los mamíferos ... more ... Universidad Nacional Autónoma de México. Título : Diversidad y conservación de los mamíferos neotropicales /. P.imprenta : México :. CONABIO :. 2002.. 582 p. : 24 cm. Notas : Incluye bibliografías. Descriptores: Mamíferos. Conservación de la vida silvestre. ...
The Austral and Neotropical America (ANA) section of the Society for Conservation Biology include... more The Austral and Neotropical America (ANA) section of the Society for Conservation Biology includes a vast territory with some of the largest relatively pristine ecosystems in the world. With more than 573 million people, the economic growth of the region still depends strongly on natural resource exploitation and still has high rates of environmental degradation and biodiversity loss. A survey among the ANA section membership, with more than 700 members, including most of the section's prominent ecologists and conservationists, indicates that lack of capacity building for conservation, corruption, and threats such as deforestation and illegal trade of species, are among the most urgent problems that need to be addressed to improve conservation in the region. There are, however, strong universities and ecology groups taking the lead in environmental research and conservation, a most important issue to enhance the ability of the region to solve conservation and development conflicts. Retos de Conservación para la Sección América Austral y Neotropical Resumen: La sección América Austral y Neotropical (AAN) de la Sociedad para la Biología de la Conser-vación incluye un vasto territorio con unos de los ecosistemas relativamente prístinos más extensos del mundo. Con más de 573 millones de habitantes, el crecimiento económico de la región aun depende fuertemente de la explotación de recursos naturales y aún tiene altas tasas de degradación ambiental y pérdida de biodi-versidad. Un sondeo de la membresía de la sección AAN, con más de 700 miembros, incluyendo la mayoría de los ecólogos y conservacionistas más prominentes de la sección, indica que la carencia de desarrollo de capacidades para la conservación, la corrupción y amenazas como la deforestación y el comercio ilegal de especies, son algunos de los problemas que requieren ser atendidos más urgentemente para mejorar la con-servación en la región. Sin embargo, hay universidades y grupos ecológicos que están tomando el liderazgo §
Background/Question/Methods The Mexico – US border, expanding more than 3,169 km (1,969 mi), is t... more Background/Question/Methods The Mexico – US border, expanding more than 3,169 km (1,969 mi), is the most crossed border in the World. It is a vast land that harbors a high diversity of ecosystems, stretching from extremely arid lands, to temperate and subtropical forests. It maintains a high biodiversity and represents either the northern or southern limits in the distribution of many plants and animals. The border region faces very complex social and economic issues, that have been exacerbated by the increasing drug traffic from Mexico to the US, fueled by an ever growing consumption of drugs in the US, and an ever increasing drug violence in Mexico. The US government is building unilaterally a wall across most of the border that is the only huma structure in the whole planet that is becoming a continental barrier for the dispersal and movements of many plants anal animals. I here present a comprehensive review the biological characteristics of the border area, the impact of the fe...
The widespread encroachment of woody plants throughout the semi-arid grasslands in North America ... more The widespread encroachment of woody plants throughout the semi-arid grasslands in North America has largely resulted from overgrazing by domestic livestock, fire suppression, and loss of native large and small mammalian herbivores. Burrowing-herbivorous mammals, such as prairie dogs (Cynomys spp.), help control shrub encroachment through clipping of shrubs and consumption of their seedlings, but little is known about how this important ecological role interacts with and may be influenced by co-existing large herbivores, especially domestic livestock. Here, we established a long-term manipulative experiment using a 2 × 2 factorial design to assess the independent and interactive effects of black-tailed prairie dogs (Cynomys ludovicianus) and cattle (Bos taurus) on honey mesquite (Prosopis glandulosa) abundance and structure. We found that, after five years, mesquite abundance was three to five times greater in plots where prairie dogs were removed compared to plots where they occurred together or alone, respectively. While both prairie dogs and cattle reduced mesquite cover, the effect of prairie dogs on reducing mesquite abundance, cover, and height was significantly greater than that by cattle. Surprisingly, cattle grazing enhanced prairie dog abundance, which, in turn, magnified the effects of prairie dogs on mesquite shrubs. Mesquite canopy cover per hectare was three to five times greater where prairie dogs and cattle were absent compared to where they occurred together or by themselves; whereas, cumulative mesquite height was two times lower on sites where prairie dog and cattle occurred together compared to where they occurred alone or where neither occurred. Data from our experimental study demonstrate that prairie dogs and moderate grazing by cattle can suppress mesquite growth, and, when their populations are properly managed, they may interact synergistically to significantly limit mesquite encroachment in desert grasslands.
The oft-repeated claim that Earth&amp... more The oft-repeated claim that Earth's biota is entering a sixth "mass extinction" depends on clearly demonstrating that current extinction rates are far above the "background" rates prevailing between the five previous mass extinctions. Earlier estimates of extinction rates have been criticized for using assumptions that might overestimate the severity of the extinction crisis. We assess, using extremely conservative assumptions, whether human activities are causing a mass extinction. First, we use a recent estimate of a background rate of 2 mammal extinctions per 10,000 species per 100 years (that is, 2 E/MSY), which is twice as high as widely used previous estimates. We then compare this rate with the current rate of mammal and vertebrate extinctions. The latter is conservatively low because listing a species as extinct requires meeting stringent criteria. Even under our assumptions, which would tend to minimize evidence of an incipient mass extinction, the average rate of vertebrate species loss over the last century is up to 100 times higher than the background rate. Under the 2 E/MSY background rate, the number of species that have gone extinct in the last century would have taken, depending on the vertebrate taxon, between 800 and 10,000 years to disappear. These estimates reveal an exceptionally rapid loss of biodiversity over the last few centuries, indicating that a sixth mass extinction is already under way. Averting a dramatic decay of biodiversity and the subsequent loss of ecosystem services is still possible through intensified conservation efforts, but that window of opportunity is rapidly closing.
Costa Rica has one of the greatest percentages (26%) of protected land in the world. The National... more Costa Rica has one of the greatest percentages (26%) of protected land in the world. The National Protected Areas System (NPAS) of Costa Rica was established in 1976 and currently includes >190 protected areas within seven different protection categories. The effectiveness of the NPAS to represent species, populations, and areas with high species richness has not been properly evaluated. Such evaluations are fundamental to understand what is necessary to strengthen the NPAS and better protect biodiversity. We present a novel assessment of NPAS effectiveness in protecting mammal species. We compiled the geographical ranges of all terrestrial Costa Rican mammals then determined species lists for all protected areas and the estimated proportion of each species’ geographic range protected. We also classified mammal species according to their conservation status using the IUCN Red List of Threatened Species. We found almost complete representation of mammal species (98.5%) in protected areas, but low relative coverage (28.3% on average) of their geographic ranges in Costa Rica and 25% of the species were classified as underprotected according to a priori representation targets. Interestingly, many species-rich areas are not protected, and at least 43% of cells covering the entire country are not included in protected areas. Though protected areas in Costa Rica represent species richness well, strategic planning for future protected areas to improve species complementarity and range protection is necessary. Our results can help to define sites where new protected areas can have a greater impact on mammal conservation, both in terms of species richness and range protection.
The diversity of Mexican mammals is one of the largest in the World. Over the past 15-years studi... more The diversity of Mexican mammals is one of the largest in the World. Over the past 15-years studies on taxonomy, syste- matics, and distribution have modi␣ed the former mammal checklist for the country. Here we present an updated checklist that comprise 13 orders, 46 families, 201 genera, and 550 species, of which 170 are endemic to Mexico. In the checlist we include data on the distribution, biogeographic affinities, and conservation status at the National and World level. We also have included distribution maps of all the species.
... Ochoa, OL 2003. ... no Almeraya, Enrique Muñoz Ló-pez, Pablo Ortuño Sánchez, Gus-tavo Ramírez... more ... Ochoa, OL 2003. ... no Almeraya, Enrique Muñoz Ló-pez, Pablo Ortuño Sánchez, Gus-tavo Ramírez Santiago, Luis Gerar-do Ramos Cruz, Rainer Ressl, Antonio Guillermo Robles Caraza, Ramón Solano Barajas, Assefaw Tewolde Medhin, Rocío Vi llal ó n Calderón, niños y ...
... Universidad Nacional Autónoma de México. Título : Diversidad y conservación de los mamíferos ... more ... Universidad Nacional Autónoma de México. Título : Diversidad y conservación de los mamíferos neotropicales /. P.imprenta : México :. CONABIO :. 2002.. 582 p. : 24 cm. Notas : Incluye bibliografías. Descriptores: Mamíferos. Conservación de la vida silvestre. ...
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