## 3 Results  
### Site-Specific Base Cation Budgets  
Site-specific base cation inputs and outputs measured at each of the ten Level II long term monitoring plots over the last 10-24 years are summarised in Table 3a,b, with base cation budgets provided in Table 4. On average across all sites, Ca output as tree uptake (33% of total) was smaller than that by leaching (67%), while Ca input by weathering was much larger (71% of total) compared to deposition (29%). Similar partitioning between deposition and weathering was also observed for Mg and K. In addition, leaching and tree uptake proportion to the total outputs varied between base cations with higher outputs by leaching for Ca and Mg than tree uptake while for K the tree uptake made a higher proportion of outputs than K leaching (Table 3b). Site Ca and Mg inputs were significantly positively related to outputs (r\({}^{2}\) = 0.75 and 0.57 respectively), while K exhibited a much weaker and not significant relationship (r\({}^{2}\) = 0.07). A small negative Ca balance was observed at Sherwood and a small negative Ca and K balance at Ramnoch and Rogate; all sites on nutrient poor, acid sandy soils and under mature Scots pine (Table 2). The Mg budget was positive for all but Theftord, which also had a borderline K balance (Table 4). As expected, Ca leaching tended to be higher for sites with deeper soils and Ca-rich geology (Alice Holt, Savernake, Theftord, Coalbum, and Tummel), with the highest leaching rate observed on the sandy soils overlying chalk at Theftord (Figure 3). Ca, Mg and K balances were significantly positively related to soil exchangeable cations (Ca (r\({}^{2}\) = 0.91, \(p\) < 0.001, \(n\) = 10), Mg (r\({}^{2}\) = 0.31, \(p\) < 0.1, \(n\) = 10) and K (r\({}^{2}\) = 0.62, \(p\) < 0.01, \(n\) = 10) (data not shown), while the overall base cation (Ca + Mg + K) budget was significantly positively related to site-specific soil cation exchange capacity (CEC) (r\({}^{2}\) = 0.89, \(p\) < 0.001, \(n\) = 10 Figure 4). Figure 3: Calcium leaching flux at shallow (10 cm depth) and deeper (50 cm depth) soil depths at the ten ICP Forest Level II monitoring sites. Figure 4: Linear relationship between total base cation (Ca + Mg + K) budget and soil cation exchange capacity (CEC) at the ICP Forest Level II monitoring sites (\(n=10\), \(r^{2}=0.89\), \(p<0.001\)). \begin{table} \begin{tabular}{l c c c c c c c c} \hline (\(\mathrm{Ab}\)) & & **Deposition** & **Weightning** & **Leaching** & **Tree Uptake** & **Deposition** & **Weaching** & **Lacking** & **Tree Uptake** \\  & & **\(\mathrm{kg\,ha^{-1}y^{-1}}\)** & \(\mathrm{kg\,ha^{-1}y^{-1}}\)** & \(\mathrm{kg\,ha^{-1}y^{-1}}\)** & \(\mathrm{kg\,ha^{-1}y^{-1}}\)** & \(\mathrm{kg\,ha^{-1}y^{-1}}\)** & \(\mathrm{kg\,ha^{-1}y^{-1}}\)** & \(\mathrm{kg\,ha^{-1}y^{-1}}\)** & \(\mathrm{kg\,ha^{-1}y^{-1}}\)** \\ \hline \hline
**Sine (free species)** & **S Soil type (WRR)** & **2009** & **1009** & **1009** & **1009** & **1009** & **1009** & **1009** \\ Alve (HoHo (Ca)) & **Emeris Verried** & 5.75 & 199.77 & 27.1 & 102.4 & 2.83 & 64.73 & 7.89 & 1.15 \\ Serumathan (Ca) & **Emeris Verried** & 5.89 & 199.77 & 36.45 & 5.11 & 2.15 & 91.11 & 13.73 & 0.81 \\ Cerenathan (Da) & **Emeris Verried** & 5.76 & 137.1 & 85.3 & 4.89 & 6.03 & 81.3 & 10.12 & 0.70 \\ Theoretical (Stein type) & **Ferrida-Armond** & 3.57 & 185.14 & 197.22 & 554.1 & 1.99 & 2.60 & 3.84 & 1.12 \\ Sherwood (Stein type) & **Emeris Verried** & 2.77 & 2.85 & 8.39 & 4.06 & 4.27 & 13.77 & 4.04 & 0.63 \\ Earwood (Stein type) & **Emeris Verried** & 2.20 & 2.03 & 3.60 & 4.08 & 2.42 & 2.60 & 3.58 & 1.17 \\ Ruggie (Stein type) & **Funkel** & 4.39 & 2.54 & 5.29 & 3.28 & 3.55 & 2.86 & 3.52 & 0.55 \\ Cerenathan (Stein types) & **Funkel** & 4.01 & 102.30 & 36.55 & 7.99 & 2.34 & 54.45 & 6.08 & 1.25 \\ Temporal (Stein types) & **Funkel** & 2.54 & 92.50 & 39.88 & 6.18 & 2.01 & 13.27 & 8.26 & 0.96 \\ LJn Biotime (Stein types) & **Unite-driven** & 5.98 & 4.98 & 0.22 & 4.58 & 7.67 & 54.45 & 4.31 & 1.28 \\ \hline \hline \end{tabular}