## 2 Data and Methods
### Data

Table 1: Name, location, vegetation type, and period of data used for each site. \begin{table}
\begin{tabular}{l l l l l l l l} \hline \hline
**Site Name** & **Country** & **Lat.** & **Long.** & **Veg.** & **Opti.** & **Vali.** & **Reference** \\  & & **(°)** & **(°)** & **Type** & **Years** & **Years** & **Reference** \\ \hline Howland Forest (HOF) & USA & 45.2 & \(-\)68.74 & MF & 2003 & 2004 & [PERSON] _et al._ (1999, 2004) \\  & & & & & & [55,56] \\ [PERSON] (HY) & Finland & 61.85 & 24.29 & NF & 2001 & 2002 & [PERSON] _et al._ (2002) [57] \\ [PERSON] (KED) & USA & 31.74 & \(-\)109.94 & GRASS & 2006 & 2007 & [PERSON] (2010) [58] \\ [PERSON] (KEN) & USA & 28.61 & \(-\)80.67 & SHRUB & 2004 & 2005 & [PERSON] _et al._ (2006) [59] \\ [PERSON] (LOB) & Netherlands & 52.17 & 5.74 & NF & 2001,2002 & 2003 & [PERSON] _et al._ (2002) [60] \\ Mead Irrigated (MEI) & USA & 41.17 & \(-\)96.48 & CROP & 2003,2004 & 2005 & [PERSON] _et al._ (2005) [61] \\ Mead Rainfed (MER) & USA & 41.18 & \(-\)96.44 & CROP & 2004 & 2005 & [PERSON] _et al._ (2005) [61] \\ Metolius Intermediate & USA & 44.45 & \(-\)121.56 & NF & 2005 & 2007 & [PERSON] _et al._ (2003) [62] and [PERSON] _et al._ (2009) [63] \\ Mead Irrigated Rotation & USA & 41.16 & \(-\)96.47 & CROP & 2004 & 2005 & [PERSON] _et al._ (2005) [61] \\ [PERSON] (MIZ) & USA & 29.76 & \(-\)82.24 & SHRUB & 2003 & 2004 & [PERSON] _et al._ (2012) [64] \\ Morgan Monroe State & USA & 39.32 & \(-\)86.41 & BF & 2003,2005 & 2006 & [PERSON] _et al._ (2000) [65] \\ Metolius New Young Pine (MNY) & USA & 44.32 & \(-\)121.6 & NF & 2004 & 2005 & [PERSON] _et al._ (2012) [66] and [PERSON] _et al._ (2012) [67] \\ Missouri Ozark (MOZ) & USA & 38.74 & \(-\)92.2 & BF & 2005,2006 & 2007 & [PERSON] _et al._ (2006) [68] \\ North Carolina Loblolly & USA & 35.8 & \(-\)76.67 & NF & 2005 & 2006 & [PERSON] _et al._ (2009) [69] \\ [PERSON] (NCL) & Austria & 47.12 & 11.32 & GRASS & 2002 & 2003 & [PERSON] _et al._ (2008) [70] \\ Niwot Ridge (NR) & USA & 40.03 & \(-\)105.55 & NF & 2003,2006 & 2007 & [PERSON] _et al._ (2002) [71] \\ ON EpeatlandMerBleue (OEM) & Canada & 45.41 & \(-\)75.52 & SHRUB & 2001 & 2004 & [PERSON] _et al._ (2003) [72] \\ Puechabon (PUE) & France & 43.74 & 3.6 & BF & 2001,2002 & 2003 & [PERSON] _et al._ (2008) [73] \\ QC-Black Spruce (QMB) & Canada & 49.69 & \(-\)74.34 & NF & 2004 & 2005 & [PERSON] _et al._ (2007) [74] \\ Qianyanzhou(QYZ) & China & 26.73 & 115.07 & NF & 2003 & 2004 & [PERSON] _et al._ (2006) [75] \\ Renon (REN) & Italy & 46.59 & 11.43 & NF & 2002 & 2003 & [PERSON] _et al._ (2009) [76] \\ Rosemount G19 (RG19) & USA & 44.72 & \(-\)93.09 & CROP & 2004,2005 & 2006 & [PERSON] _et al._ (2008) [77] \\ Rosemount G21 (RG21) & USA & 44.71 & \(-\)93.09 & CROP & 2004,2005 & 2006 & [PERSON] _et al._ (2009) [78] \\ Rocarespampani (ROC) & Italy & 42.39 & 11.92 & BF & 2002 & 2003 & [PERSON] _et al._ (2009) [79] \\ Sky Oaks New (SON) & USA & 33.38 & \(-\)116.64 & SHRUB & 2004,2005 & 2006 & [PERSON] _et al._ (2007) [80] \\ [PERSON] (SOR) & Denmark & 55.48 & 11.65 & MF & 2001,2002 & 2003 & [PERSON] _et al._ (2001) [81] \\ Santa Rita Mesquite (SRM) & USA & 31.82 & \(-\)110.87 & SHRUB & 2004,2005 & 2006 & [PERSON] (2010) [58] \\ San Rossore (SRO) & Italy & 43.73 & 10.29 & NF & 2001,2002 & 2003 & [PERSON] _et al._ (2011) [82] \\ [PERSON] (THA) & Germany & 50.96 & 13.57 & NF & 2001,2002 & 2003 & Grunwald and Bernhofer \\  & & & & & & (2007) [83] \\ [PERSON] (TMK) & Japan & 42.74 & 141.52 & NF & 2001,2002 & 2003 & [PERSON] _et al._ (2003) [84] \\ Tonzi Ranch (TRA) & USA & 38.43 & \(-\)120.97 & SHRUB & 2004,2005,2006 & 2007 & [PERSON] _et al._ (2004) [85] \\ UCI 1850 (U50) & Canada & 55.88 & \(-\)98.48 & NF & 2003 & 2004 & [PERSON] _et al._ (2011) [86] \\ UCI 1989 (U89) & Canada & 55.92 & \(-\)98.96 & SHRUB & 2003 & 2004 & [PERSON] _et al._ (2011) [86] \\ UCI 1998 (U98) & Canada & 56.64 & \(-\)99.95 & SHRUB & 2003 & 2004 & [PERSON] _et al._ (2011) [86] \\ UMBS (UMBS) & USA & 45.56 & \(-\)84.71 & BF & 2003,2004 & 2006 & [PERSON] _et al._ (2005) [87] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._