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\hypersetup{pdftitle={Aboveground Net Primary Production Response to Chronic Nitrogen Addition in a Tropical Montane Forest },pdfauthor={Angelica Baldos, Marife D. Corre},pdfsubject={Tropentag 2011: Abstract},pdfkeywords={Aboveground net primary production, chronic nitrogen addtion, tropical forest},pdfpagemode=None,colorlinks=true}
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\parbox[b]{13.4cm}{\centering \large{\textbf{Tropentag, October 5-7, 2011, Bonn}}\\[1ex] \Large{``Development on the margin''\\[2ex]}}
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\Large{\textbf{Aboveground Net Primary Production Response to Chronic Nitrogen Addition in a Tropical Montane Forest \footnote{\textbf{Contact Address:} Angelica Baldos, Georg-August-Universität Göttingen, Institute for Soil Sciene and Forest Nutrition, Buesgenweg 2, 37077~Goettingen, Germany, \mbox{e-mail}: \email{abaldos@gwdg.de}}\\[0.8ex]}}
\normalsize{\textsc{Angelica Baldos, Marife D. Corre}}
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\begin{itemize*}
\item[]{\small{\textit{Georg-August-Universität Göttingen, Institute for Soil Sciene and Forest Nutrition, Germany}}}
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\index[author]{Baldos, Angelica}
\index[author]{Corre, Marife D.}
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\textbf{Abstract}
\begin{abstract}
\normalsize{
Nitrogen (N) deposition in tropical areas is projected to increase rapidly in the next decades and little is known on how tropical forest productivity will respond to increase in N availability. We used an N-addition experiment to achieve an N-enriched condition in an old"=growth forest growing in an Aluandic Andosol soil at 1200--1300-m elevation in Fortuna Forest Reserve, Panama. Control and N-addition treatments (starting in 2006 at a rate of \mbox{125\,kg} urea-N ha$^{-1}$ yr$^{-1}$, split in four applications) were laid out in paired"=plots design with four replicate plots (40mx\mbox{40\,m} each, separated by $\geq$40-m distance). Here, we report the changes in various components of above"=ground net primary production (ANPP) during the 3--4-yr N addition: stem diameter growth (separated by diameter at breast height (DBH) classes of 10--\mbox{30\,cm}, 30--\mbox{50\,cm}, and $>$\mbox{50\,cm}), woody biomass production (WBP) and fine litterfall. No significant differences were observed between 3--4-yr N addition and the control in stem diameter growth of any DBH classes or all classes combined (control: 1.6$\pm$0.2 mm yr$^{-1}$; N-addition plots: 1.9$\pm$0.2 mm yr$^{-1}$), in WBP (control: 4.3$\pm$0.6 Mg ha$^{-1}$ yr$^{-1}$; N-addition plots: 4.2$\pm$0.5 Mg ha$^{-1}$ yr$^{-1}$), in total fine litterfall (control: 7.3$\pm$0.4 Mg ha$^{-1}$ yr$^{-1}$; N-fertilised: 8.0$\pm$0.4 Mg ha$^{-1}$ yr$^{-1}$), and in ANPP (control: 11.6$\pm$0.8 Mg ha$^{-1}$ yr$^{-1}$; N-fertilised: 12.3$\pm$0.8 Mg ha$^{-1}$ yr$^{-1}$). The first 2 years of N addition showed significant increase in ANPP compared to the control, and this was mainly due to increased leaf"=litter production (Adamek et al. 2009). Our results showed interannual variation of ANPP response to N addition.}

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\noindent \textbf{Keywords:} Aboveground net primary production, chronic nitrogen addtion, tropical forest
\index[key]{Aboveground net primary production}
\index[key]{Chronic nitrogen addtion}
\index[key]{Tropical forest}
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