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...

We report the association of Cristulariella moricola (Hino) Redhead with a zonate leaf spot on Eucalyptus benthamii (Myrtaceae). We observed the disease outbreak across a series of experimental E. benthamii plantings in Barnwell County, South Carolina, USA in October 2015. The disease caused nearly complete foliar necrosis of most trees in one experimental planting, but disease incidence remained at low levels (<10% of foliage affected in most trees) in other plantings. Disease development coincided with periods of extended rainfall, which has also been observed in outbreaks of zonate leaf...

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...

In a pair of review papers, Potter (2012a, 2012b) summarized the significant fire weather research findings over about the past hundred years. Our scientific understanding of wildland fire-atmosphere interactions has evolved: from simple correlations supporting the notion that hot, dry, and windy conditions lead to more intense fires, we have moved towards more mechanistic and physical descriptions of governing processes such as fuel moisture dynamics, wind-driven fire spread, the influence of vortices, and plume dynamics. Our advances are important not only for the sake of scientific...

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...

Climate change in the 21st century is likely to dramatically alter the growing conditions that Pacific Northwest tree species experience. It has been suggested that foresters plan for these changes by moving seed sources to locations where the seed-source environment and the future climate will be similar. Some people have called this type of seed-source movement “assisted migration” with the idea that we are helping the plants move to better suited sites faster than they would naturally. But it is important to realize that people have moved seed sources to new locations for centuries...

Investments in urban forests have been increasing in many US cities. Urban forests have been shownto provide countless ecosystem benefits with many addressing climate change issues, such as seques-tering carbon, reducing air pollution, and decreasing the heat island effect. Individual groups within theAmerican public may not respond to the issue of climate change in the same way, thus engaging eachgroup in climate change solutions will require different approaches. It is therefore important to under-stand how the public perceives climate change, their values and preferences, and barriers...