Changing climate response in near-treeline bristlecone pine with elevation and aspect

In the White Mountains of California, eight bristlecone pine (Pinus longaeva) tree-ring width chronologies were developed from trees at upper treeline and just below upper treeline along North- and South-facing elevational transects from treeline to ~90 m below. There is evidence for a climate-response threshold between approximately 60–80 vertical m below treeline, above which trees have shown a positive growth-response to temperature and below which they do not. Chronologies from 80 m or more below treeline show a change in climate response and do not correlate strongly with temperature-sensitive chronologies developed from trees growing at upper treeline. Rather, they more closely resemble lower elevation precipitation-sensitive chronologies. At the highest sites, trees on South-facing slopes grow faster than trees on Northfacing slopes. High growth rates in the treeline South-facing trees have declined since the mid1990s. This suggests the possibility that the climate-response of the highest South-facing trees may have changed and that temperature may no longer be the main limiting factor for growth on the South aspect. These results indicate that increasing warmth may lead to a divergence between tree growth and temperature at previously temperature-limited sites.

[1]  Andrew G. Bunn,et al.  Statistical and visual crossdating in R using the dplR library , 2010 .

[2]  M. Berkelhammer,et al.  Modeled and observed intra-ring δ18O cycles within late Holocene Bristlecone Pine tree samples , 2009 .

[3]  J. Kok,et al.  The physics of wind-blown sand and dust , 2012, Reports on progress in physics. Physical Society.

[4]  M. Stokes,et al.  An Introduction to Tree-Ring Dating , 1996 .

[5]  T. Wigley,et al.  On the Average Value of Correlated Time Series, with Applications in Dendroclimatology and Hydrometeorology , 1984 .

[6]  E. Cook,et al.  A CHANGING TEMPERATURE RESPONSE WITH ELEVATION FOR LAGAROSTROBOS FRANKLINII IN TASMANIA, AUSTRALIA , 1997 .

[7]  M. Hughes,et al.  Extremes of moisture availability reconstructed from tree rings for recent millennia in the great basin of western north America , 1998 .

[8]  E. Cook,et al.  Methods of Dendrochronology - Applications in the Environmental Sciences , 1991 .

[9]  Malcolm K. Hughes,et al.  Topographically modified tree-ring chronologies as a potential means to improve paleoclimate inference , 2011 .

[10]  P. Jones,et al.  Updated high‐resolution grids of monthly climatic observations – the CRU TS3.10 Dataset , 2014 .

[11]  Malcolm K. Hughes,et al.  Dendroclimatology in High-Resolution Paleoclimatology , 2011 .

[12]  Edmund Schulman,et al.  Dendroclimatic Changes in Semiarid America , 1957 .

[13]  B. Liepert,et al.  On the ' Divergence Problem ' in Northern Forests : 2 3 4 A Review of the Tree-Ring Evidence and Possible 5 Causes , 2007 .

[14]  S. Leavitt,et al.  An annually resolved bristlecone pine carbon isotope chronology for the last millennium , 2011, Quaternary Research.

[15]  M. Hughes,et al.  Recent unprecedented tree-ring growth in bristlecone pine at the highest elevations and possible causes , 2009, Proceedings of the National Academy of Sciences.

[16]  N. Graham,et al.  Five millennia of paleotemperature from tree-rings in the Great Basin, USA , 2014, Climate Dynamics.

[17]  Andrew G. Bunn,et al.  A dendrochronology program library in R (dplR) , 2008 .

[18]  G. Faluvegi,et al.  Global Signatures and Dynamical Origins of the Little Ice Age and Medieval Climate Anomaly , 2009, Science.

[19]  Valerie Trouet,et al.  KNMI Climate Explorer: A Web-Based Research Tool for High-Resolution Paleoclimatology , 2013 .

[20]  F. H. Schweingruber,et al.  Reduced sensitivity of recent tree-growth to temperature at high northern latitudes , 1998, Nature.

[21]  S. Leavitt,et al.  Temporal stability in bristlecone pine tree-ring stable oxygen isotope chronologies over the last two centuries , 2010 .

[22]  K. Kipfmueller,et al.  Reconstructed Temperature And Precipitation On A Millennial Timescale From Tree-Rings In The Southern Colorado Plateau, U.S.A. , 2005 .

[23]  M. Berkelhammer,et al.  Recent and dramatic changes in Pacific storm trajectories recorded in δ18O from Bristlecone Pine tree ring cellulose , 2008 .

[24]  S. Leavitt,et al.  Major wet interval in white mountains medieval warm period evidenced inδ13C of bristlecone pine tree rings , 1994 .

[25]  V. Lamarche,et al.  Paleoclimatic Inferences from Long Tree-Ring Records , 1974, Science.

[26]  K. Kipfmueller,et al.  Linear trend and climate response of five-needle pines in the western United States related to treeline proximity. , 2010 .

[27]  V. Lamarche,et al.  Chronologies from Termperature-Sensitive Bristlecone Pines at Upper Treeline in Western United States , 1974 .

[28]  E. Cook,et al.  Long-Term Aridity Changes in the Western United States , 2004, Science.