Journal Article

Recent unprecedented tree-ring growth in bristlecone pine at the highest elevations and possible causes

Bunn, Andrew G, Salzer, Matthew W, Kipfmueller, Kurt F, Hughes, Malcolm K

2009

Overview

Great Basin bristlecone pine (Pinus longaeva) at 3 sites in western North America near the upper elevation limit of tree growth showed ring growth in the second half of the 20th century that was greater than during any other 50-year period in the last 3,700 years. The accelerated growth is suggestive of an environmental change unprecedented in millennia. The high growth is not overestimated because of standardization techniques, and it is unlikely that it is a result of a change in tree growth form or that it is predominantly caused by CO₂ fertilization. The growth surge has occurred only in a limited elevational band within [almost equal to]150 m of upper treeline, regardless of treeline elevation. Both an independent proxy record of temperature and high-elevation meteorological temperature data are positively and significantly correlated with upper-treeline ring width both before and during the high-growth interval. Increasing temperature at high elevations is likely a prominent factor in the modern unprecedented level of growth for Pinus longaeva at these sites.

• Publisher: National Academy of Sciences,National Acad Sciences
• Subject: Air Pollution - analysis / air temperature / Altitude / Biological Sciences / California / Carbon dioxide / Climate / Climate change / Climate models / dendrochronology / Dendroclimatology / Environmental changes / Fertilization / Forest growth / Geography / global warming / Growth rings / Models, Biological / Nevada / Paleoclimatology / Pinus - growth & development / Pinus longaeva / Plant growth / Plant Stems - anatomy & histology / Plant Stems - growth & development / Rain / Temperature / Timberlines / Tree growth / Treeline / Trees