Fire injury can increase tree susceptibility to some bark beetles (Curculionidae, Scolytinae), but whether wildfires can trigger outbreaks of species such as mountain pine beetle (Dendroctonus ponderosae Hopkins) is not well understood. We monitored 1173 lodgepole (Pinus contorta var. latifolia Doug.) and 599 ponderosa (Pinus ponderosa Doug. ex Law) pines for three years post-wildfire in the Ui...

Two new species of Cladosporium found on necrotic needles of Pinus ponderosa trees in Patagonia, Argentina, are described as C. chubutense and C. pini-ponderosae. An additional isolate from dead leaves of Cortaderia collected in Colombia, which is a sister taxon to the species occurring on Pinus, is described as Cladosporium colombiae. These species are phylogenetically closely related, but dif...

[1] Mountain pine beetle (Dendroctonus ponderosae) outbreaks in North America are widespread and have potentially large-scale impacts on albedo and associated radiative forcing. Mountain pine beetle outbreaks in Colorado and southern Wyoming have resulted in persistent and significant increases in both winter albedo (change peaked 10 years post outbreak at 0.06 ± 0.01 and 0.05 ± 0.01, in lodgep...

Pine Island Glacier (PIG) terminates in a rapidly melting ice shelf, and ocean circulation and temperature are implicated in the retreat and growing contribution to sea level rise of PIG and nearby glaciers. However, the variability of the ocean forcing of PIG has been poorly constrained due to a lack of multi-year observations. Here we show, using a unique record close to the Pine Island Ice S...

Ecosystem simulation models are designed to assess the flux of energy, water, carbon and nitrogen according to a given vegetation type. The reliability of the modeled results is determined by model validations. Model validations are typically done using classical statistical methods like regression analysis of predicted versus observed values, paired t statistics and error assessment procedures...

Single-vein leaves have the simplest hydraulic design possible, yet even this linear water delivery system can be modulated to improve physiological performance. We determined the optimal distribution of transport capacity that minimizes pressure drop per given investment in xylem permeability along the needle for a given length without a change in total water delivery, or maximizes needle leng...

High-value trees, such as those located in residential, recreational, or administrative sites, are particularly susceptible to bark beetle (Coleoptera: Curculionidae: Scolytinae) attack as a result of increased amounts of stress associated with drought, soil compaction, mechanical injury, or vandalism. Tree losses in these unique environments generally have a substantial impact. The value of th...

Eight Pleistocene wood rat middens at elevations of 1200, 880, and 600 meters in the Chihuahuan Desert contain abundant macrofossils of pinyon pine, juniper, shrubby liveoak, and Opuntia, together with smaller quantities of Agave lecheguilla and other xerophytes of existing desert vegetation, which in dicate a xerophilous woodland vegetation in the lowlands, as much as 800 meters below existing...

The pine shoot beetle, Tomicus piniperda (L.), is an exotic pest that has become established in North America. Discovered in Ohio in 1992, it has since been found in at least 13 states and parts of Canada. The beetle can cause significant growth loss in pines, and it represents a potential threat to trees in areas where it has not yet become established. To evaluate this threat to native pines,...