from Needle Production in Pinus sylvestris at the Northern Timberline: a Tool for Evaluating Palaeoclimate

• Main Authors: Risto Jalkanen, Sheila Hicks, Tarmo Aalto, Hannu Salminen
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: annual resolution; needle trace method; NTM; pollen accu- mulation rate; Scots pine; temperature reconstruction; tree line; Arctic; The Needle
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.555.6434; http://www.metla.fi/silvafennica/full/sf42/sf424499.pdf

needle production in Pinus sylvestris at the northern timberline: a tool for evaluating palaeo-climate reconstructions. Silva Fennica 42(4): 499–513. Annual needle production (PROD) of Scots pine (Pinus sylvestris L.) and pine pollen accumu-lation rates (PAR) are compared along a 5-site transect from the Arctic Circle to the northern timberline. PROD is calculated using the Needle Trace Method (NTM). PAR is monitored by two series of pollen traps, located in the centres of mires and within forests, respectively. There is a strong year-to-year agreement in PAR and PROD between the sites for the common 19-year period for which both proxies are available. Mean July temperature of the previous year (TJUL–1) correlates statistically significantly with PROD at all five sites and with PAR in the four northernmost sites. There is also a significant relationship between TJUN–1 and PROD at all sites, and TJUN and PAR at the two northernmost sites. PROD and PAR correlate most strongly in the three near tree line sites, where PROD explains up to 51 % of the variation in PAR. On the basis of the calibration between PROD, PAR and TJUL–1, PROD and TJUL–1 are used to reconstruct past PAR. That such a reconstruction is realistic is supported by its agreement with the pollen record for 1982–2000 and with records of male flowering for the