Removal of the lichen mat by reindeer enhances tree growth in a northern Scots pine forest

• Published in: Canadian Journal of Forest Research
• Main Authors: Macias Fauria, Marc, Helle, Timo, Niva, Aarno, Posio, Heikki, Timonen, Mauri
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2008
• Subjects: Fennoscandian; Rangifer tarandus
• Online Access: http://dx.doi.org/10.1139/x08-135; http://www.nrcresearchpress.com/doi/full-xml/10.1139/X08-135; http://www.nrcresearchpress.com/doi/pdf/10.1139/X08-135

Reindeer ( Rangifer tarandus L.) lichen grazing enhanced Scots pine ( Pinus sylvestris L.) growth in a northeastern Fennoscandian forest. Lichen mat removal by grazing in a previously ungrazed area increased soil versus air temperature coupling. This caused faster soil spring warming and higher soil temperatures during late spring and summer, which are related to an earlier start of and better growth conditions during the trees’ growing season. Tree growth was related to spring and summer climate during the study period, 1896–2001. Snowmelt date, and ultimately soil warming and start of the growing season, may have caused the relationships between tree growth and spring climate. A drop in July temperature and an increase in the spring signals were found and attributed to the “divergence problem,” a widespread weakening in the relationships between tree growth and summer temperature in northern latitudes observed in the late 20th century. Differences in the relationships between tree growth and climate were found between trees growing in grazed and ungrazed parts of the stand. Tree growth differences were detected ∼10 years after the removal of the lichen mat. The fertilizing effect of reindeers on tree growth was considered minimal in this study, but its influence cannot be completely ruled out. Grazing intensity may thus be an important component of boreal forest carbon uptake.