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We analyzed variation in canopy closure around 47 Mexican spotted owl (Strix occidentalis lucida) nest sires and 47 random forest sites on the Coconino National Forest in northcentral Arizona. We mapped distinct habitat polygons on 1:15,840 color aerial photographs, assigned each polygon to one of 4 canopy-closure classes (70%), and measured the area in each canopy class within 5 concentric analysis zones with radii of 0.1, 0.4, 0.8, 1.2, and 1.6 km (delineating rings of about 4, 47, 150, 252, and 352 ha). Landscape composition differed between spotted owl nest and random sites (P 70% canopy-closure class and less area in the 70% canopy predominated Nesting spotted owls selected areas with denser canopy than randomly...
Fire risk in western North America has increased with increasing cover of Bromus tectorum, an invasive alien annual grass. The relationship between B. tectorum cover and fire risk was determined in a historically burned Artemisia tridentata-Poa secunda shrub?steppe community where B. tectorum cover ranged from 5 to 75%. Fire risk ranged from ~46% with an average of 12% B. tectorum cover to 100% when B. tectorum cover was greater than 45% based on prediction confidence limits. Reflectance of the green and red bands of aerial photographs were related to senescent B. tectorum cover to create fine resolution B. tectorum cover and fire risk maps. This assessment technique will allow land managers to prioritize lands...
Dam removal is often implemented without adequate baseline monitoring to distinguish background variability from channel changes due to the removal. This study evaluated aerial photos as substitutes for multiple-year pre-removal field data to assess downstream channel changes associated with a small dam removal. The Brownsville Dam, a 2.1 m tall concrete dam on the Calapooia River, Oregon, was removed in 2007. We mapped bars and the low flow channel downstream from the dam and in an upstream control reach using aerial photos (1994-2008) and in the field prior to (2007) and following (2008) removal. The locations and magnitudes of changes in bar area and wetted width, relative to errors, indicate that downstream...
    map background search result map search result map Canopy closure around nest sites of Mexican spotted owls in northcentral Arizona Canopy closure around nest sites of Mexican spotted owls in northcentral Arizona