Treesearch

Flowery rhetoric often gives birth to new terms that convey images and concepts, lead to inspiration and initiative. On the 1892-1894 expedition to resurvey the United States-Mexico boundary, Lieutenant David Dubose Gaillard described the Arizona-Sonora borderlands as “bare, jagged mountains rising out of the plains like islands from the sea” (Mearns 1907; Hunt and Anderson 2002). Later Galliard was the lead engineer on the Panama Canal construction project.

Attendees of the annual Santa Cruz River Researchers’ Day meetings have identified a need to expand collaboration, partnership, and sharing of lessons learned across the watershed. To help guide this interest, Sonoran Institute organized a symposium on 2 May 2012 entitled “Santa Cruz River Conservation.” The symposium had simultaneous Spanish/English translation and featured (1) presentations of work being done within the watershed in Mexico, (2) a binational mapping session to inventory current knowledge of conservation efforts in the watershed, and (3) a discussion and invitation to...

Climate change is affecting natural systems on a global scale and is particularly rapid in the Southwest. It is important to identify impacts of a changing climate before ecosystems become unstable. Recognizing plant responses to climate change requires knowledge of both species present and plant responses to variable climatic conditions. A conceptual model derived from observations made during a 28-year phenological study is presented and implications for monitoring ecosystem change are discussed.

Highly variable moisture conditions in the Sonoran Desert play a significant role in shaping the composition and phenology of plants in this water-limited region. The flowering patterns of plants of the Finger Rock trail, located in the Santa Catalina Mountains of southern Arizona, have been very carefully documented on approximately a weekly basis for nearly three decades. These observations, made along a gradient encompassing more than 4,000 ft in elevation, have revealed that flower presence, timing, and duration vary dramatically from year to year for many species in this unique...

The Rothermel surface fire spread model includes a wind speed limit, above which predicted rate of spread is constant. Complete derivation of the wind limit as a function of reaction intensity is given, along with an alternate result based on a changed assumption. Evidence indicates that both the original and the revised wind limits are too restrictive. Wind limit is based in part on data collected on the 7 February 1967 Tasmanian grassland fires. A reanalysis of the data indicates that these fires might not have been spreading in fully cured continuous grasslands, as assumed. In addition,...

In this article we develop a simulation model to evaluate the economic efficiency of fuel treatments and apply it to two sagebrush ecosystems in the Great Basin of the western United States: the Wyoming Sagebrush Steppe and Mountain Big Sagebrush ecosystems. These ecosystems face the two most prominent concerns in sagebrush ecosystems relative to wildfire: annual grass invasion and native conifer expansion. Our model simulates long-run wildfire suppression costs with and without fuel treatments explicitly incorporating ecological dynamics, stochastic wildfire, uncertain fuel treatment...

Factors influencing invasive taxa may change during the course of an invasion. For example, intraspecific competition is predicted to be more important in areas with older stands of dense monospecific invaders than at the margins of an invaded range. We evaluated evolution in response to predicted changes in competition by comparing the intraspecific competitive ability of North American populations of Japanese honeysuckle (Lonicera japonica) from areas established 100-150 yr ago, which make up the core of the invaded range, to populations from the northern range margin, established in the...

An extensive program of experiments focused on biomass burning emissions began with a laboratory phase in which vegetative fuels commonly consumed in prescribed fires were collected in the southeastern and southwestern US and burned in a series of 71 fires at the US Forest Service Fire Sciences Laboratory in Missoula, Montana. The particulate matter (PM2.5) emissions were measured by gravimetric filter sampling with subsequent analysis for elemental carbon (EC), organic carbon (OC), and 38 elements. The trace gas emissions were measured by an open-path Fourier transform infrared (OP-FTIR)...

The burning rate of unconfined cribs has long been identified to occur in two regimes: the densely-packed regime where the burning rate is proportional to the crib porosity and the loosely-packed regime where the burning rate is independent of porosity. Though the cribs used to define these burning regimes were primarily cubic in dimension, there are seemingly endless possible ways to build a crib with a given porosity. This work explores the burning rate of cribs with a wide variety of geometries to determine whether the porosity-burning rate relation in the literature holds. One set of...

The Wildland Fire Decision Support System (WFDSS) web-based application leverages geospatial data to inform strategic decisions on wildland fires. A specialized data team, working within the Wildland Fire Management Research Development and Application group (WFM RD&A), assembles authoritative national-level data sets defining values to be protected. The use of such high-quality trusted data ensures that critical resources, infrastructure and firefighter risk exposure are considered in both the planning and implementation phases of incident management (Figure 3 and Table 1).