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Nitrogen deposition outweighs climatic variability in driving annual growth rate of canopy beech trees: Evidence from long‐term growth reconstruction across a geographic gradient
Author(s) -
Gentilesca Tiziana,
Rita Angelo,
Brunetti Michele,
Giammarchi Francesco,
Leonardi Stefano,
Magnani Federico,
Noije Twan,
To Giustino,
Borghetti Marco
Publication year - 2018
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.14142
Subject(s) - beech , precipitation , environmental science , canopy , atmospheric sciences , physical geography , montane ecology , deposition (geology) , dendrochronology , climatology , ecology , geography , forestry , biology , geology , meteorology , paleontology , archaeology , sediment
In this study, we investigated the role of climatic variability and atmospheric nitrogen deposition in driving long‐term tree growth in canopy beech trees along a geographic gradient in the montane belt of the Italian peninsula, from the Alps to the southern Apennines. We sampled dominant trees at different developmental stages (from young to mature tree cohorts, with tree ages spanning from 35 to 160 years) and used stem analysis to infer historic reconstruction of tree volume and dominant height. Annual growth volume ( G V ) and height ( G H ) variability were related to annual variability in model simulated atmospheric nitrogen deposition and site‐specific climatic variables, (i.e. mean annual temperature, total annual precipitation, mean growing period temperature, total growing period precipitation, and standard precipitation evapotranspiration index) and atmospheric CO 2 concentration, including tree cambial age among growth predictors. Generalized additive models ( GAM ), linear mixed‐effects models ( LMM ), and Bayesian regression models ( BRM ) were independently employed to assess explanatory variables. The main results from our study were as follows: (i) tree age was the main explanatory variable for long‐term growth variability; (ii) GAM , LMM , and BRM results consistently indicated climatic variables and CO 2 effects on G V and G H were weak, therefore evidence of recent climatic variability influence on beech annual growth rates was limited in the montane belt of the Italian peninsula; (iii) instead, significant positive nitrogen deposition (N dep ) effects were repeatedly observed in G V and G H ; the positive effects of N dep on canopy height growth rates, which tended to level off at N dep values greater than approximately 1.0 g m −2 y −1 , were interpreted as positive impacts on forest stand above‐ground net productivity at the selected study sites.