Responses of white spruce (Picea glauca) to experimental warming at a subarctic alpine treeline Export

@article{citeulike:1103266, abstract = {From 2001 to 2004 we experimentally warmed 40 large, naturally established, white spruce [Picea glauca (Moench) Voss] seedlings at alpine treeline in southwest Yukon, Canada, using passive open-top chambers (OTCs) distributed equally between opposing north and south-facing slopes. Our goal was to test the hypothesis that an increase in temperature consistent with global climate warming would elicit a positive growth response. OTCs increased growing season air temperatures by 1.8°C and annual growing degree-days by one-third. In response, warmed seedlings grew significantly taller and had higher photosynthetic rates compared with control seedlings. On the south aspect, soil temperatures averaged 1.0°C warmer and the snow-free period was nearly 1 month longer. These seedlings grew longer branches and wider annual rings than seedlings on the north aspect, but had reduced Photosystem-II efficiency and experienced higher winter needle mortality. The presence of OTCs tended to reduce winter dieback over the course of the experiment. These results indicate that climate warming will enhance vertical growth rates of young conifers, with implications for future changes to the structure and elevation of treeline contingent upon exposure-related differences. Our results suggest that the growth of seedlings on north-facing slopes is limited by low soil temperature in the presence of permafrost, while growth on south-facing slopes appears limited by winter desiccation and cold-induced photoinhibition.}, author = {Danby, Ryan K. and Hik, David S.}, citeulike-article-id = {1103266}, citeulike-linkout-0 = {http://dx.doi.org/10.1111/j.1365-2486.2006.01302.x}, citeulike-linkout-1 = {http://www.ingentaconnect.com/content/bsc/gcb/2007/00000013/00000002/art00009}, citeulike-linkout-2 = {http://www3.interscience.wiley.com/cgi-bin/abstract/117991521/ABSTRACT}, doi = {10.1111/j.1365-2486.2006.01302.x}, issn = {1354-1013}, journal = {Global Change Biology}, keywords = {climate, ibutton, inpro, thermochron}, month = {February}, number = {2}, pages = {437--451}, posted-at = {2008-09-12 13:35:48}, priority = {2}, publisher = {Blackwell Publishing}, title = {Responses of white spruce (Picea glauca) to experimental warming at a subarctic alpine treeline}, url = {http://dx.doi.org/10.1111/j.1365-2486.2006.01302.x}, volume = {13}, year = {2007} }

TY - JOUR ID - citeulike:1103266 L3 - citeulike-article-id:1103266 N2 - From 2001 to 2004 we experimentally warmed 40 large, naturally established, white spruce [Picea glauca (Moench) Voss] seedlings at alpine treeline in southwest Yukon, Canada, using passive open-top chambers (OTCs) distributed equally between opposing north and south-facing slopes. Our goal was to test the hypothesis that an increase in temperature consistent with global climate warming would elicit a positive growth response. OTCs increased growing season air temperatures by 1.8°C and annual growing degree-days by one-third. In response, warmed seedlings grew significantly taller and had higher photosynthetic rates compared with control seedlings. On the south aspect, soil temperatures averaged 1.0°C warmer and the snow-free period was nearly 1 month longer. These seedlings grew longer branches and wider annual rings than seedlings on the north aspect, but had reduced Photosystem-II efficiency and experienced higher winter needle mortality. The presence of OTCs tended to reduce winter dieback over the course of the experiment. These results indicate that climate warming will enhance vertical growth rates of young conifers, with implications for future changes to the structure and elevation of treeline contingent upon exposure-related differences. Our results suggest that the growth of seedlings on north-facing slopes is limited by low soil temperature in the presence of permafrost, while growth on south-facing slopes appears limited by winter desiccation and cold-induced photoinhibition. IS - 2 JF - Global Change Biology SN - 1354-1013 EP - 451 TI - Responses of white spruce (Picea glauca) to experimental warming at a subarctic alpine treeline PB - Blackwell Publishing VL - 13 SP - 437 KW - climate KW - ibutton KW - inpro KW - thermochron AU - Danby, Ryan AU - Hik, David PY - 2007/02// UR - http://dx.doi.org/10.1111/j.1365-2486.2006.01302.x ER -