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Chronic nitrogen deposition alters tree allometric relationships: implications for biomass production and carbon storage
Author(s) -
Ibáñez Inés,
Zak Donald R.,
Burton Andrew J.,
Pregitzer Kurt S.
Publication year - 2016
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1890/15-0883
Subject(s) - allometry , tree allometry , biomass (ecology) , deposition (geology) , environmental science , productivity , atmospheric sciences , ecosystem , nitrogen , carbon fibers , ecology , primary production , carbon sequestration , mathematics , biology , biomass partitioning , chemistry , carbon dioxide , geology , paleontology , macroeconomics , organic chemistry , sediment , economics , algorithm , composite number
Abstract As increasing levels of nitrogen (N) deposition impact many terrestrial ecosystems, understanding the potential effects of higher N availability is critical for forecasting tree carbon allocation patterns and thus future forest productivity. Most regional estimates of forest biomass apply allometric equations, with parameters estimated from a limited number of studies, to forest inventory data (i.e., tree diameter). However, most of these allometric equations cannot account for potential effects of increased N availability on biomass allocation patterns. Using 18 yr of tree diameter, height, and mortality data collected for a dominant tree species ( Acer saccharum ) in an atmospheric N deposition experiment, we evaluated how greater N availability affects allometric relationships in this species. After taking into account site and individual variability, our results reveal significant differences in allometric parameters between ambient and experimental N deposition treatments. Large trees under experimental N deposition reached greater heights at a given diameter; moreover, their estimated maximum height (mean ± standard deviation: 33.7 ± 0.38 m) was significantly higher than that estimated under the ambient condition (31.3 ± 0.31 m). Within small tree sizes (5–10 cm diameter) there was greater mortality under experimental N deposition, whereas the relative growth rates of small trees were greater under experimental N deposition. Calculations of stemwood biomass using our parameter estimates for the diameter–height relationship indicated the potential for significant biases in these estimates (~2.5%), with under predictions of stemwood biomass averaging 4 Mg/ha lower if ambient parameters were to be used to estimate stem biomass of trees in the experimental N deposition treatment. As atmospheric N deposition continues to increase into the future, ignoring changes in tree allometry will contribute to the uncertainty associated with aboveground carbon storage estimates across a forest with a large geographic distribution in eastern North America.