Data from: Low photosynthesis of treeline white spruce is associated with limited soil nitrogen availability in the Western Brooks Range, Alaska ...

• Main Authors: McNown, Robert W., Sullivan, Patrick F.
• Format: Dataset
• Language: English
• Published: Dryad 2013
• Subjects: sink limitation; Picea glauca; source limitation; Snow; Holocene; Arctic; Brooks Range; Alaska
• Online Access: https://dx.doi.org/10.5061/dryad.s5c8k; https://datadryad.org/stash/dataset/doi:10.5061/dryad.s5c8k

1. The prevailing hypothesis states that treeline positions are defined by the direct effects of cold temperatures on cell division and tree growth. Meanwhile, photosynthesis is thought to be relatively unrestricted in treeline trees. Support for this hypothesis comes from the global correlation between temperature and treeline position, the observation that many treelines have advanced in response to recent warming and the frequent use of increment cores from treeline trees to reconstruct past climates. However, studies of the physiology of trees at the Arctic treeline are rare and this hypothesis remains largely untested. 2. To improve our understanding of the relationships between temperature and performance of white spruce near the Arctic treeline, we made measurements of needle gas exchange, needle nutrition and soil nutrient availability over two years in three contrasting habitats: riverside terrace, hillslope forest and treeline. The sites had similar aboveground microclimates, but very different ... : Ion Exchange MembranesEstimates of nutrient availability from ion exchange membranes installed on June 28, 2011 and retrieved on August 9, 2011 in eight plots at each site. Two cation and two anion membranes were installed in each plot and extracted together.Growing Season MicroclimatesHourly measurements of air temperature, humidity, photosynthetically active radiation, rain, soil temperature and soil water content at each of the sites between early June and late September of the 2010 and 2011 growing seasons.Needle Gas ExchangeMeasurements of light-saturated net photosynthesis, dark respiration and stomatal conductance made on approximately one-week intervals during the 2010 and 2011 growing seasons in three habitat types.Needle N, 15N and PhotosynthesisMeasurements of needle nitrogen concentration, needle 15N and needle net photosynthesis on the final sampling date in each of the habitats during late August of 2010 and 2011.Seasonal Needle N and 13CMeasurements of needle N concentration and needle 13C ...