Upper San Pedro Grasslands Watershed Restoration Methods

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Coronado National Memorial and Rancho Los Fresnos are situated within the upper San Pedro transboundary watershed along the U.S.-Mexico border. Both of these protected areas are subject to both historical and recent stressors associated with human occupation. These sites are situated within the semiarid grasslands and savanna of the Huachuca Mountains Grassland Valley Complex, which was identified as the top priority conservation area of 90 key conservation areas identified in the Apache Highlands ecoregion during a binational scientific analysis of target richness (biological diversity) and uniqueness (or irreplaceability; Marshall et al., 2004). The Sonoita grasslands priority conservation area (CEC and TNC, 2005) constitutes a subset of the aforementioned grasslands valley complex. This area has diverged from its native condition due to human activities including intensive grazing of livestock, altered fire regimes, altered hydrologic function, invasive plant species, population growth and climate change (Marshall et al., 2004; AGF, 2012). Along the U.S.-Mexico border proper, activities related to illegal entry to the U.S. from Mexico and security measures countering these activities have created a zone of expanding disturbance and soil erosion that, left untreated, threatens the long-term integrity of the grassland-savanna bajada of the southern Huachuca Mountains at Coronado National Memorial and Rancho Los Fresnos, a protected area managed by Naturalia, A.C., adjacent to the border in Sonora, Mexico.

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