Treesearch

Buffel savannas have been an important landscape on cattle grazing ranches in Sonora over the past 50 years or more. Changes in land use result in biodiversity changes that may produce ecosystem functional changes; however, these are less well documented. Although fire driven processes have been proposed for Buffel savannas, this is not generally the case, and other processes seem to be driving ecosystem function. Several years of studying above- and below ground processes allow us to propose how microclimate, water and nutrient dynamics change in established Buffel savannas, as well as...

Pines are important dominants in pine-oak, pine and mixed-conifer forests across the Colorado Plateau, southern Rocky Mountains, Sierra Madre Occidental, and in the intervening Sky Islands of the United States-Mexico borderlands. All 17 native species of pines in the Sky Islands region or their adjacent mountain mainlands reach the northern or southern margins of their geographic ranges and most (12) have Madrean vs. Petran affinities. We compiled data on the occurrence and diversity of pines across 31 Sky Islands based on extensive fieldwork that complemented data from museum collections....

The Sierra Madre Occidental (SMO) is the largest continuous ignimbrite plate on Earth. Despite its high biological and cultural diversity and enormous environmental and economical importance, it is yet not well known. We describe the vegetation and present a preliminary regionalization based on physiographic, climatic, and floristic criteria. A confluence of three main ecoregions in the area corresponds with three ecosystems: Temperate Sierras (Madrean), Semi-Arid Highlands (Madrean Xerophylous) and Tropical Dry Forests (Tropical). The Madrean region harbors five major vegetation types:...

Although the Sonoran Desert does not have the highest plant species richness, it has been documented with the highest growth form diversity from the North American deserts. It is not known if this high growth form diversity could also harbor a high functional diversity. In this study we characterize the ecophysiological functional traits of photosynthetic capacity, stomatal conductance, transpiration and resource use efficiency (water and nitrogen), as well as morphological and structural traits of specific leaf area and nitrogen content in 52 species that inhabit the arid and semiarid...

The long separation of the Chihuahuan and Sonoran Deserts is reflected in the high species richness and endemism of their floras. Although many endemic species from both deserts reach their distributional limits where the Sierra Madre Occidental massif fragments into smaller mountain complexes in northern Mexico and adjoining areas of the United States, indicator species approaches to identify the boundary between the Chihuahuan and Sonoran Deserts are complicated by differences in physiology and morphology among species that independently influence their local occurrences. Here we use an...

A total of 555 plant collections were made on 20 trips in 2002-2008 to La Calera area in the Sierra Anibácachi, Municipio de Agua Prieta, 11.3 km south of the Arizona border (31°13’59”N 109°37’53”W, elevation range from 1220 m to 1539 m) in northeastern Sonora. Chihuahuan desertscrub on limestone substrates is dominated by creosotebush (Larrrea divaricata), Chihuahuan whitethorn (Acacia neovernicosa), mariola (Parthenium incanum), and tarbush (Flourensia cernua). Riparian vegetation along a rocky bedrock/ gravel wash includes desert willow (Chilopsis linearis), netleaf hackberry (Celtis...

Transects were done in desertscrub on limestone to characterize the flora of the westernmost Chihuahuan Desert. Most of the sites (15) were in the Municipios of Agua Prieta and Naco in northeastern Sonora, with single sites near Ascensión, northwestern Chihuahua and east of Douglas in southeastern Arizona. A total of 236 taxa were recorded on transects. Dicot perennial herbs (66 species) were the most numerous life forms, followed by annual herbs (36 species), subshrubs (36 species), and woody shrubs (33 species). The most diverse limestone floras were on Rancho La Morita in the Municipio...

The Sierra Bacadéhuachi in east-central Sonora is the westernmost mountain range in the Sierra Madre Occidental (SMO), located east of Bacadéhuachi, Municipio de Bacadéhuachi, 34 km east of the Chihuahua border, and 165 km south of the Arizona border. The vegetation ranges from lowland foothills thornscrub up through desert grassland to oak woodland and pine-oak forest. The flora was sampled in December 1995, July 2008, June, August, and September 2011, and March 2012. The flora totals 442 taxa in 297 genera and 96 families. The most species-rich families and genera are Asteraceae (53...

The floras of the tropical vegetation in the Sky Island Sierra la Madera (SMA) near Moctezuma in northeastern Sonora (30°00’N 109°18’W) and the Yécora (YEC) area in the Sierra Madre Occidental (SMO) in eastern Sonora (28°25’N 109°15”W) were compared. The areas are 175 km apart. Tropical vegetation includes foothills thornscrub (FTS) in both areas and tropical deciduous forest (TDF) in the Yécora area. A total of 893 vascular plant taxa are known from these areas with 433 taxa in FTS and 793 in TDF. FTS in SMA and YEC (near Curea) had 220 and 298 taxa, with most of them also in TDF (69.5%...

A large artificial sand dune composed of finely crushed mine tailings was produced by deep mining operations at Ruby, Arizona. Today, the ghost town of Ruby is an important historical location and biodiversity refuge, with the newly formed dune forming the core of the refuge. The dune provides ideal nesting habitat for at least 13 species of sand-loving wasps, including cicada killers (Hymenoptera: Sphecius) that are sometimes present in record breaking populations. Following the colonizing wasps were at least 14 species of velvet ants (Hymenoptera: Mutillidae) that parasitize the wasps....