• Fire Temperatures and Physical Characteristics of a Controlled Burn in the Upper Sonoran Desert

      Patten, D. T.; Cave, G. H. (Society for Range Management, 1984-05-01)
      Fire temperatures at 4 vertical locations within 3 desert microhabitats were measured during a controlled burn using both temperature pellets and thermocouples. Examples of maximum air temperatures (30 cm) during the fire were 138 degrees C in open interspaces, 352 degrees C within a shrub, and 442 degrees C under a palo verde tree. Fire temperatures among other levels and microhabitats varied considerably. Environmental conditions during the fire were monitored. Soil water repellency at 4 vertical locations within 3 microhabitats showed minimal changes after burning. Soil surface albedo increased by 5% following the fire resulting from 70% perennial plant cover removal and subsequent white ash release. Soil and air temperatures did not vary significantly after the fire when compared to an unburned control.
    • Responses of Birds, Rodents, and Vegetation to Livestock Exclosure in a Semidesert Grassland Site

      Bock, C. E.; Bock, J. H.; Kenney, W. R.; Hawthorne, V. M. (Society for Range Management, 1984-05-01)
      Livestock have been excluded from a 3,160-ha range in southeastern Arizona since 1968. Compared to an adjacent continuously grazed area, in 1981-82 a protected upland site supported 45% more grass cover, a comparatively heterogeneous grass community, and 4 times as many shrubs. Grama grasses (Bouteloua spp.) were equally common in and outside the exclosure, while a variety of other species, especially plains lovegrass (Eragrostis intermedia) and Arizona cottontop (Trichachne californicum) were much more abundant on the protected site. The grazed area supported significantly higher numbers of birds in summer, while densities did not differ in winter. Rodents were significantly more abundant inside the protected area. Species of birds and rodents more common in the grazed area included those typical of more xeric lowland habitats and those preferring open ground for feeding. Species more common on the protected site were those which characterize semidesert or plains grasslands, and which prefer substantial grass or shrub cover. Grazing appeared to favor birds as a class over rodents.