Maestas, J. D., Knight, R. L., & Gilgert, W. C. (2003). Biodiversity across a Rural Land‐Use Gradient. Conservation Biology, 17(5), 1425-1434.
Private lands in the American West are undergoing a land-use conversion from agriculture to exurban development, although little is known about the ecological consequences of this change. Some nongovernmental organizations are working with ranchers to keep their lands out of development and in ranching, ostensibly because they believe biodiversity is better protected on ranches than on exurban developments. However, there are several assumptions underlying this approach that have not been tested. To better inform conservation efforts, we compared avian, mesopredator, and plant communities across the gradient of intensifying human uses from nature reserves to cattle ranches to exurban developments. We conducted surveys at randomly selected points on each type of land use in one Colorado watershed between May and August of 2000 and 2001. Seven bird species, characterized as human commensals or tree nesters, reached higher densities (all p < 0.02) on exurban developments than on either ranches or reserves. Six bird species, characterized as ground and shrub nesters, reached greater densities (all p < 0.015) on ranches, reserves, or both of these types of land use than on exurban developments. Domestic dogs (Canis familiaris) and house cats (Felis catus) were encountered almost exclusively on exurban developments, whereas coyotes (Canis latrans) were detected more frequently (p = 0.047) on ranchlands than exurban developments. Ranches had plant communities with higher native species richness and lower non-native species richness and cover than did the other types of land use (all p < 0.10). Our results support the notion that ranches are important for protecting biodiversity and suggest that future conservation efforts may require less reliance on reserves and a greater focus on private lands.
Private lands in the American West are undergoing a land-use conversion from agriculture to exurban development, although little is known about the ecological consequences of this change. Some nongovernmental organizations are working with ranchers to keep their lands out of development and in ranching, ostensibly because they believe biodiversity is better protected on ranches than on exurban developments. However, there are several assumptions underlying this approach that have not been tested. To better inform conservation efforts, we compared avian, mesopredator, and plant communities across the gradient of intensifying human uses from nature reserves to cattle ranches to exurban developments. We conducted surveys at randomly selected points on each type of land use in one Colorado watershed between May and August of 2000 and 2001. Seven bird species, characterized as human commensals or tree nesters, reached higher densities (all p < 0.02) on exurban developments than on either ranches or reserves. Six bird species, characterized as ground and shrub nesters, reached greater densities (all p < 0.015) on ranches, reserves, or both of these types of land use than on exurban developments. Domestic dogs (Canis familiaris) and house cats (Felis catus) were encountered almost exclusively on exurban developments, whereas coyotes (Canis latrans) were detected more frequently (p = 0.047) on ranchlands than exurban developments. Ranches had plant communities with higher native species richness and lower non-native species richness and cover than did the other types of land use (all p < 0.10). Our results support the notion that ranches are important for protecting biodiversity and suggest that future conservation efforts may require less reliance on reserves and a greater focus on private lands.
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Los terrenos privados del oeste de América están experimentando una conversión del suelo de un uso agrícola a un uso urbano, aunque se conoce poco acerca de las consecuencias ecológicas de este cambio. Algunas organizaciones no gubernamentales están trabajando con granjeros para que sus tierras permanezcan sin urbanizar, ostensiblemente porque piensan que la biodiversidad se protege mejor en tierras rurales que en urbanizaciones. Sin embargo, hay varios supuestos subyacentes a este modelo que no han sido comprobadas. Para informarnos mejor sobre los esfuerzos de conservación, comparamos comunidades de aves, mesodepredadores y plantas a lo largo del gradiente de intensidad de uso humano de reservas naturales, granjas y zonas de urbanización. Realizamos muestreos en sitios seleccionados aleatoriamente en cada uso de suelo en una cuenca del Colorado entre mayo y agosto de 2000 y 2001. Siete especies de aves, caracterizadas como comensales humanos o nidificantes arbóreos, alcanzaron densidades más altas (todas p < 0.02) en urbanizaciones nuevas que en granjas o reservas. Seis especies de aves, caracterizadas como nidificantes de suelo y arbustos, alcanzaron densidades mayores (todas p < 0.015) en granjas, reservas o usos mixtos del suelo que en las nuevas urbanizaciones. Se encontraron perros (Canis familiaris) y gatos (Felis catus) domésticos casi exclusivamente en nuevas urbanizaciones, mientras que se detectaron coyotes (Canis latrans) más frecuentemente (p = 0.047) en granjas que en nuevas urbanizaciones. Las granjas tenían comunidades de plantas con mayor riqueza de especies nativas y menor riqueza y cobertura de especies no nativas que en todos los demás usos de suelo (todas p < 0.10). Nuestros resultados apoyan la noción de que las granjas son importantes para la protección de la biodiversidad y sugieren que los futuros esfuerzos de conservación pueden requerir de menos confianza en las reservas y un mayor enfoque en terrenos privados.
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