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Roots were collected at all NUMEX Plots (ECSF) in January 2009, except Ca treatments. 3 subplots were sampled per plot. Roots were stained with Trypan Blue and the percentage of root colonization determined using the line-intersect method.

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Measurements of gas flux (CO2, CH4, N2O) in canopy soils of NUMEX plots on four dates (Sept/Nov 2011 and Jan/April 2012). Measurements were taken in 3 of the 4 NUMEX blocks at each elevation; treatments measured included C, N, NP and P.

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Monthly time series of d13C and d15N isotope measurements in litterfall at NUMEX San Francisco between 2007 and 2009. Litterfall was collected on all 20 plots at NUMEX on 6 subplots per plot (A-F) with polyethylene mesh traps (0.6 x 0.6 m). On each plot, two of the six litterfall traps were randomly sampled monthly. The samples were dried at 40 °C for one week and stored at the ECSF until transport to Germany or Switzerland for chemical analyses. The two collected replicates were bulked per plot and collecting interval resulting in one litterfall sample per plot and month. Samples were ground to <50 µm with a planetary ball mill (Retsch PM200, Haan, Germany) prior to isotope measurements of d13C and d15N by EA/IRMS (ThermoFisher, Bremen, Germany)

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Soil aggregation parameters were measured in NUMEX at 1000m in 2013. Water-stable soil aggregates were determined as well as the mean weight diameter of soil based on dry-sieving.

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Fortnightly time series of measured concentrations of Cl, PO4-P, Total P, NH4-N, NO3-N, Total N, K, Na, Mg, Ca and Total organic C in soil solution (30 cm mineral soil depth) at NUMEX San Francisco. The fortnightly time series extends between August 2007 and March 2013. Soil solution was sampled on the 20 NUMEX plots with ceramic suction cups having a pore size of 1 µm installed at 30 cm depth in the mineral soil. On each plot 3 replicates were collected and bulked to one sample per plot. The samples were stored at -20 °C until transport in frozen state to Germany or to Switzerland for concentration measurements.

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Monthly time series of measured concentrations of Al, Cu, Fe, Mn, Zn, C, N, S, P, K, Na, Mg, Ca in litterfall at NUMEX San Francisco between 2007 and 2013. Litterfall was collected on all 20 plots at NUMEX on 6 subplots per plot (A-F) with polyethylene mesh traps (0.6 x 0.6 m). On each plot, two of the six litterfall traps were randomly sampled monthly. The samples were dried at 40 °C for one week and stored at the ECSF until transport to Germany or Switzerland for chemical analyses. The two collected replicates were bulked per plot and collecting interval resulting in one litterfall sample per plot and month. Samples were ground to <50 µm with a planetary ball mill (Retsch PM200, Haan, Germany) prior to elemental analysis of C, N, and S by thermal combustion (Elementar Analysensysteme, Hanau, Germany) and acid microwave digestion with concentrated HNO3. Element concentrations in the digested samples were measured by AAS, ICP-OES or ICP-MS.

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Fortnightly time series of measured concentrations of Cl, PO4-P, Total P, NH4-N, NO3-N, Total N, K, Na, Mg, Ca and Total organic C in litter leachate at NUMEX San Francisco. The fortnightly time series extends between August 2007 and March 2013. Litter leachate was sampled on the 20 NUMEX plots with tero-tension lysimeters below the organic layer. On each plot 3 replicates were collected, volume-weighted and bulked to one sample per plot. Samples were immediately filtered (4-7 µm) in the laboratory of the ECSF and stored at -20 °C until transport in frozen state to Germany or to Switzerland for concentration measurements.

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Arbuscular mycorrhizal root colonization (%), colonized root length (cm/cm³) and fine root parameters in response to nutrient additions (N, P and NP) are reported. Samples were taken in October 2010 at the NUMEX plots at 2000m.

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Fortnightly time series of measured electrical conductivity and pH values in soil solution (30 cm mineral soil depth) at NUMEX San Francisco. The fortnightly time series extends between August 2007 and December 2016. Soil solution was sampled on the 20 NUMEX plots with ceramic suction cups having a pore size of 1 µm installed at 30 cm depth in the mineral soil. On each plot 3 replicates were collected and bulked to one sample per plot. Electrical conductivity and pH values were measured immediately in unfiltered aliquots in the laboratory of the ECSF.