Loblolly pine (Pinus taeda L.) and shortleaf pine (Pinus echinata Mill.) have widely overlapping geographic ranges. Hybridization between the two species has interested tree breeders for a long time. Morphologically, the two pine species are different. The needles of loblolly pine are 6 to 9 inches long, usually with three yellow-green needles per fascicle; but shortleaf pine needles are 3 to 5...

Recent research demonstrates how the occurrence of a preemptive competitor (Tamiasciurus) gives rise to a geographic mosaic of coevolution for crossbills (Loxia) and conifers. We extend these studies by examining ponderosa pine (Pinus ponderosa), which produces more variable annual seed crops than the conifers in previous studies and often cooccurs with tree squirrels in the genus Sciurus that ...

Pine cones that remain closed and retain seeds until fire causes the cones to open (cone serotiny) represent a key adaptive trait in a variety of pine species. In lodgepole pine, there is substantial geographical variation in serotiny across the Rocky Mountain region. This variation in serotiny has evolved as a result of geographically divergent selection, with consequences that extend to fores...

Amethodology has been developed for defining the various threshold conditions required for the opening of serotinous cones and viable seed release in the overstorey canopies in jack pine (Pinus banksiana) and lodgepole pine (Pinus contorta var. latifolia) forests on the basis of fireline intensity and, in turn, rate of fire spread and fuel consumption. The extent of the effects to the overstore...

Path finders: Humans can use higher cognitive functions to combine information from a range of sources when they’re trying to find their way, but how do insects achieve this? (Photo: Getty Images.) Just over 80 years ago, a young biologist in Leiden, in the Netherlands, handed in a PhD thesis that was only 29 pages long and had been written up in a mad hurry, as the author was keen to join a sp...

Pine seed mass is isometrically related to samara shape among smaller seeded pines (< 165 mg), but not when larger seeds are included (putative bird-dispersed pines excluded). Among the largest pine seeds samara length declines with increases in seed mass. Consequently, disc-loading increases and dispersal capacity declines at an accelerating rate with increases in seed mass. The acceleration i...

I report on the attraction of the white pine cone beetle, Conophthoru.s coniperda (Schwarz) (Coleoptera: Scolytidae), to traps baited with the host monoterpene limonene in western North Carolina. Both (+)- and (-)-limonene attracted male and female cone beetles to Japanese beetle traps in an eastern white pine, Pinus strobus L., seed orchard near Murphy, NC. Catches of cone beetles were directl...

-Slash pine is the premier tree species on many sites throughout the South. Its ease of establishment and early growth, however, has extended its range to many sites where its performance has been less than ideal. For that reason, the acreage and volume of slash pine are declining. Nonetheless, it will continue to be the favored species on many sites where it is the most appropriate and product...

Asymmetrical competition determines which of two seed predators drives the evolution of lodgepole pine (Pinus contorta ssp. latifolia) cones. Red squirrels (Tamiasciurus hudsonicus) are effective preemptive competitors in lodgepole pine forests so that red crossbills (Loxia curvirostra) are uncommon and selection from Tamiasciurus drives cone evolution. When Tamiasciurus are absent, crossbills ...