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Heatwave 2003: high summer temperature, rather than experimental fertilization, affects vegetation and CO 2 exchange in an alpine bog
Author(s) -
Gerdol Renato,
Bragazza Luca,
Brancaleoni Lisa
Publication year - 2008
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2008.02429.x
Subject(s) - sphagnum , peat , bog , vascular plant , ecosystem , respiration , environmental science , ecosystem respiration , nutrient , litter , phosphorus , vegetation (pathology) , biogeochemical cycle , nitrogen , ecology , agronomy , chemistry , botany , biology , primary production , medicine , organic chemistry , pathology , species richness
Summary• Nitrogen and phosphorus were added experimentally in a bog in the southern Alps. It was hypothesized that alleviating nutrient limitation will increase vascular plant cover. As a consequence, more carbon will be fixed through higher rates of net ecosystem CO 2 exchange (NEE). • The vascular cover did increase at the expense of Sphagnum mosses. However, such vegetation changes were largely independent of the treatment and were probably triggered by an exceptional heatwave in summer 2003. • Contrary to the tested hypothesis, NEE was unaffected by the nutrient treatments but was strongly influenced by temperature and water‐table depth. In particular, ecosystem respiration in the hot summer of 2003 increased dramatically, presumably owing to enhanced heterotrophic respiration in an increased oxic peat layer. • At the end of the experiment, the Sphagnum cover decreased significantly in the nitrogen‐fertilized treatment at hummock microhabitats. In the long term, this will imply a proportionally greater accumulation of vascular litter, more easily decomposable than the recalcitrant Sphagnum litter. As a result, rates of carbon fixation may decrease because of stimulated respiration.