## Materials and Methods
### Biometric Measurements and Estimation of NPP\({}_{bm}\)
#### NPP of Total Woody Biomass, Leaves and Fruits  
From 2007 until 2017, at the end of growing season, the \(DBH\) of all trees (\(DBH\) > 2 cm) in each of the 24 plots (Figures 2 and A1) were measured with a measuring tape at 1 mm precision. In addition, in April 2008, a total of 643 aluminium dendrometer bands were installed on all trees on the plots having \(DBH\) larger than 7.5 cm for the assessment of short-term (weekly to monthly) stem increments. Dendrometer bands have been self-made in the Croatian Forest Research Institute according to the method that was described by [PERSON] and [PERSON] (2008). During the vegetation season, cumulative stem circumference increments were measured on dendrometers with a precision of 0.01 mm, using small callpers with an electronic display. The frequency of measurements varied from weekly to monthly during the growing season, with lower frequency in most recent years due to the limitation in resources. The error of the measurement was estimated to be around 1% of the measured increment ([PERSON] and [PERSON], 2010). The effect of the initial'settling' of the dendrometer band on a tree stem during 2008, which, if unaccounted for, could result with underestimation of increment during the first year, has been estimated and the increment was corrected, as described in ([PERSON] and [PERSON], 2010). Tree heights (\(h\)) of all trees were also measured each year (with the exception of 2011) using Vertex III hyposometers (Haglof Sweden AD, Langsele, Sweden). This provided sample data for constructing species-specific, age-dependent height curves using adjusted Michailoff function ([PERSON] and [PERSON], 2010) (Table A2). Volume (\(V\)\({}_{\geq\,3\,\mathrm{cm}}\)), over bark, of tree stem, and branches (\(d\)\(\geq\) 3 cm), was assessed with the allometric equation of [PERSON] and [PERSON] (2008) using local, species-specific parameters (Table A3) ([PERSON] and Young, 2010; [PERSON] and Young, 2010; [PERSON], 2010). The volume of thin branches and twigs (\(d\)\(<\) 3 cm in diameter) was assumed to be 5% of \(V\)\({}_{\geq\,3\,\mathrm{cm}}\)([PERSON] and Young, 2010). The volume of below ground coarse roots (>2 mm) was calculated assuming a constant, species-invariant root-to-shoot (\(RS\)) ratio of 0.257. The value of \(RS\) ratio was obtained as the average of the \(RS\) ratios for stands with pedunculate oak published in ([PERSON] and Young, 2010). Total tree volume was converted to biomass using species-specific basic wood densities (\(BWD\)), namely 450, 630, 570, and 580 kg m\({}^{-3}\) for _Alnus glutinosa_, _Carpinus betulus_, _Frazinus angusifolia_, and _Quercus robur_, respectively ([PERSON] and Young, 2010), and converted to carbon using a carbon fraction (\(CF\)) of 0.50 ([PERSON], 2010; [PERSON], 2010). Carbon stock (\(C\)) at the time of measurement (\(t\)) was calculated for each component of tree \(i\) as:  
\[\left. \begin{aligned} \text{stem and branches}:& C_{S+B,\,i}(t) =\ V_{\geq 3\,cm,i}(t)\ \times\ BWD\ \times\ CF\}\\ \text{twigs}:& C_{T,\,i}(t)\ =\ 0.05\ \times\ C_{S+B,\,i}(t)\\ \text{roots}:& C_{R,\,i}(t)\ =\ RS\ \times\left(C_{S+B,\,i}(t)+C_{T,\,i}(t) \right)\\ \text{total tree woody biomass}:& C_{WBI,\,i}(t)\ =\ \left(C_{S+B,\,i}(t)+C_{T,\,i}(t)+C_{R,\,i}(t) \right).\end{aligned} \right\} \tag{8}\]  
The \(NPP\) was calculated from changes in \(C_{i}\) at a given plot.