The trans-border flora of the San Bernardino National Wildlife Refuge in Arizona and Rancho San Bernardino in Sonora has 541 taxa in 316 genera and 86 families. The most diverse families are Poaceae (88 taxa), Asteraceae (84 taxa), Fabaceae (28 species), Euphorbiaceae (24 species), Amaranthaceae (18 species), Boraginaceae and Solanaceae (17 species each), and Brassicaceae (15 species).
In our region, true plains grassland is restricted to a few areas, primarily in northwest Chihuahua, the bootheel of New Mexico, and valleys south and west of the Huachuca Mountains. There are other small patches in northeast Sonora and southeast Arizona.
Historically, true valley grassland were more widespread and dominated the upper Santa Cruz River valley in Sonora, the Sulphur Springs, San Simon, and Animas Valleys, among others. Most of these grasslands have been converted to shrubland, barren ground, agriculture, or more of a semi-desert grassland.
Interest in the new philosophy of ecosystem management led the Forest Service to sponsor a study of past land use in the Lone Mountain/San Rafael Valley Ecosystem Project Area, part of the Sierra Vista Ranger District of Coronado National Forest in southern Arizona. In order to better understand the cumulative impacts on the project area, the agency requested an historical chronology of human occupation of the area, with a focus on natural resource use and an analysis of the impacts of historic land use, over the period from Euroamerican contact to the twentieth century.
A hunter's trail camera snapped a photo of a jaguars tail on Sept. 23, 2012.
Grasslands of central and southern Arizona, southwestern New Mexico and northern Mexico, an area known as the Apache Highlands Ecoregion, have undergone dramatic vegetation changes over the last 130 years, including encroachment by shrubs, loss of perennial grass cover, and spread of non-native species. Changes in grassland composition and structure have not occurred uniformly across the region and their extent and distribution are poorly understood at a regional scale. Moreover, these changes are dynamic and ongoing.
Rancho Los Fresnos is in the upper San Pedro river watershed. It has some of the nicest grasslands in all of Sonora and is actively managed by the Nature Conservancy and Naturalia. It is mostly ungrazed and has had natural fire regimes returned.
