Global warming: Yet another threat to Southwest's iconic pinyon pine?

Over the past decade, researchers have documented the increased vulnerability of large stands of a Southwestern forest icon – the pinyon pine – to the dangers associated with a warming climate: drought, insects, and wildfires.  Now, it appears that rising temperatures could also put a damper on pinyon reproduction, potentially limiting the ability of trees that survive the other scourges to recolonize disturbed areas, a recent study says.  Across nine stands of pinyon – two at the western tip of Oklahoma's panhandle and seven throughout New Mexico – the production of seed-bearing cones dropped 40 percent from a 10-year period centered on 1974 to another centered on 2008. Looking only at years of exceptional seed-cone production, known as masting years, cone production fell 43 percent from the earlier decade to the recent one. Meanwhile, the average temperature during the growing season in the two periods increased by 1.3 degrees Celsius (2.3 degrees Fahrenheit). The study represents a first look at the potential impact of a warming climate on the production of pinyon seeds, which, in addition to being vital to repopulating pinyon forests, are also an important source of food for wildlife, notes Miranda Redmond, a University of Colorado PhD student who led the study...more