Treesearch

Plants restricted to active sand dunes possess traits that enable both survival in a harsh environment and local migration in response to a shifting habitat mosaic. We examined seed bank dynamics of Penstemon haydenii S. Watson (blowout penstemon) in relation to local sand movement. We measured within-year sand movement along a 400 m transect and examined plant density, seed production, and seed density in relation to this movement. Plant densities were highest in areas of moderate sand movement. Annual seed rain averaged 13 seeds·m-2, whereas persistent seed bank density (0-10 cm depth)...

The exotic annual grass Bromus tectorum (cheatgrass) dominates vast acreages of rangeland in the western USA, leading to increased fire frequency and ecosystem degradation that is often irreversible. Episodic regeneration failure (“die-off”) has been observed in cheatgrass monocultures and can have negative ecosystem consequences, but can also provide an opportunity for restoration of native species and ecological function within the imperiled sagebrush steppe ecosystem. Proximate causes of cheatgrass die-off are uncertain, although several taxa of fungal soil pathogens have been implicated...

Gene flow is an evolutionary process that supports genetic connectivity and contributes to the capacity of species to adapt to environmental change. Yet, for most species, little is known about the specific environmental factors that influence genetic connectivity, or their effects on genetic diversity and differentiation. We used a landscape genetic approach to understand how geography and climate influence genetic connectivity in a foundation riparian tree (Populus angustifolia), and their relationships with specieswide patterns of genetic diversity and differentiation. Using multivariate...

We tested 3-methylcyclohex-2-en-1-one (MCH) and an Acer kairomone blend (AKB) as repellent semiochemicals for area and single tree protection to prevent spruce beetle (Dendroctonus rufipennis Kirby) attacks at locations in Utah and New Mexico. In the area protection study, we compared host infestation rates of MCH applications at three densities (20, 40, and 80 g MCH ha-1) against a control treatment over 0.64 ha plots centered within ~1.25 ha treatment blocks. All treatments included two baited funnel traps within the plot to assure spruce beetle pressure. Following beetle attack, plots...

Apex predators fulfil potentially vital ecological roles. Typically wide-ranging and charismatic, they can also be useful surrogates for biodiversity preservation, making their targeted conservation imperative. The Sri Lankan leopard (Panthera pardus kotiya), an endangered, endemic sub-species, is the island’s apex predator. Of potential keystone importance, this carnivore also fulfills "umbrella" and "flagship" criterion and is of high ecological and existence value. Apex predator conservation requires identifying factors underlying distribution, so we used multi-scale maximum entropy...

The effects of climate oscillations on spatial and temporal variations in wildland fire potential in the continental U.S. are examined from 1979 to 2015 using cyclostationary empirical orthogonal functions (CSEOFs). The CSEOF analysis isolates effects associated with the modulated annual cycle and the El Niño–Southern Oscillation (ENSO). The results show that, in early summer, wildland fire potential is reduced in the southwest during El Niño but is increased in the northwest, with opposite trends for La Niña. In late summer, El Niño is associated with increased wildland fire potential in...

Manipulation of forest spatial patterns has become a common objective in restoration prescriptions throughout the central and southern Rocky Mountain dry-mixed conifer forest systems. Pre-Euro-American settlement forest reconstructions indicate that frequent-fire regimes developed forests with complex mosaics of individual trees, tree clumps of varying size, and openings. While it is broadly agreed upon that restoration to these forest conditions will improve ecosystem function, development of treatment prescriptions that can achieve desired spatial patterns on the landscape have been met...

One crucial component of large fire response in the United States (US) is the sharing of wildland firefighting resources between regions: resources from regions experiencing low fire activity supplement resources in regions experiencing high fire activity. An important step towards improving the efficiency of resource sharing and related policies is to develop a better understanding of current assignment patterns. In this paper we examine the set of interregional wildland fire engine assignments for incidents in California and the Southwest Geographic Coordination Areas, utilising data...

Wildfire’s economic, ecological and social impacts are on the rise, fostering the realisation that business-as-usual fire management in the United States is not sustainable. Current response strategies may be inefficient and contributing to unnecessary responder exposure to hazardous conditions, but significant knowledge gaps constrain clear and comprehensive descriptions of how changes in response strategies and tactics may improve outcomes. As such, we convened a special session at an international wildfire conference to synthesise ongoing research focused on obtaining a better understand...

Despite large commitments of personnel and equipment to wildfire suppression, relatively little is known about the factors that affect how many resources are ordered and assigned to wildfire incidents and the variation in resources across incident management teams (IMTs). Using detailed data on suppression resource assignments for IMTs managing the highest complexity wildfire incidents (Type 1 and Type 2), this paper examines daily suppression resource use and estimates the variation in resource use between IMTs. Results suggest that after controlling for fire and landscape characteristics,...