## 3 Results and Discussion
\begin{table}
\begin{tabular}{l c c c c c c c} \hline Four categories of & \multicolumn{4}{c}{EVI} & \multicolumn{4}{c}{NDVI} \\ explanatory variables & mean & \(\pm\) SD & min & max & mean & \(\pm\) SD & min & max \\ \hline _Natural Land Cover_ & & & & & & & \\ Snow/ice & 0.10 & 0.04 & 0.02 & 0.23 & 0.15 & 0.08 & 0.00 & 0.45 \\ Barren/sparsely vegetated & 0.18 & 0.07 & 0.02 & 0.52 & 0.23 & 0.10 & 0.00 & 0.68 \\ Grassland & 0.23 & 0.08 & 0.01 & 0.59 & 0.37 & 0.13 & 0.00 & 0.86 \\ Shrubland/woodland & 0.24 & 0.08 & 0.01 & 0.60 & 0.40 & 0.14 & 0.00 & 0.87 \\ Forest & 0.26 & 0.08 & 0.01 & 0.61 & 0.41 & 0.15 & 0.00 & 0.87 \\ _Biogeoclimate Zone_ & & & & & & & \\ (Sub)nival & 0.10 & 0.04 & 0.02 & 0.23 & 0.11 & 0.06 & 0.00 & 0.34 \\ Alpine & 0.17 & 0.07 & 0.03 & 0.42 & 0.17 & 0.08 & 0.01 & 0.48 \\ Boreal & 0.19 & 0.08 & 0.03 & 0.50 & 0.19 & 0.10 & 0.01 & 0.64 \\ Cool Temperate & 0.20 & 0.07 & 0.01 & 0.57 & 0.29 & 0.12 & 0.00 & 0.85 \\ Warm Temperate & 0.24 & 0.08 & 0.00 & 0.62 & 0.40 & 0.15 & 0.00 & 0.88 \\ Mediterranean & 0.26 & 0.08 & 0.01 & 0.60 & 0.44 & 0.14 & 0.00 & 0.87 \\ _Season_ & & & & & & & \\ Winter & 0.19 & 0.06 & 0.01 & 0.49 & 0.25 & 0.11 & 0.00 & 0.72 \\ Spring & 0.23 & 0.07 & 0.01 & 0.55 & 0.33 & 0.11 & 0.00 & 0.72 \\ Summer & 0.25 & 0.09 & 0.01 & 0.67 & 0.39 & 0.14 & 0.00 & 0.87 \\ Autumn & 0.19 & 0.07 & 0.01 & 0.50 & 0.32 & 0.13 & 0.00 & 0.81 \\ _(Inter)annual_ & & & & & & & \\
2000 & 0.21 & 0.07 & 0.01 & 0.55 & 0.32 & 0.13 & 0.00 & 0.80 \\
2001 & 0.22 & 0.07 & 0.01 & 0.56 & 0.33 & 0.12 & 0.00 & 0.79 \\
2002 & 0.22 & 0.07 & 0.01 & 0.55 & 0.32 & 0.12 & 0.00 & 0.78 \\
2003 & 0.22 & 0.08 & 0.02 & 0.56 & 0.33 & 0.12 & 0.00 & 0.78 \\
2004 & 0.21 & 0.07 & 0.01 & 0.55 & 0.32 & 0.12 & 0.00 & 0.77 \\
2005 & 0.21 & 0.07 & 0.01 & 0.54 & 0.32 & 0.12 & 0.00 & 0.77 \\
2006 & 0.21 & 0.07 & 0.01 & 0.55 & 0.32 & 0.12 & 0.00 & 0.77 \\ Grand mean & 0.21 & 0.07 & 0.01 & 0.55 & 0.32 & 0.12 & 0.00 & 0.78 \\ \hline \end{tabular}
\end{table} 
Table 2: MODIS NDVI and EVI properties in response to changes in natural land cover, biogeoclimate zone, season, and year. Spatially disaggregated time series plots (Figures 2 to 4) show that the highest mean amplitudes were observed in the seasonal EVI for (sub)nival snow/ice, and alpine barren/sparsely vegetated land and in the seasonal NDVI for alpine barren/sparsely vegetated land, and boreal forest. The highest interannual variability in the amplitude value occurred for Mediterranean shrubland/woodland in the NDVI time series between the periods of 2000 to 2003 and 2003 to 2007. This transition from the high to the low NDVI amplitudes may be induced by natural events, or human management practices in Mediterranean shrubland/woodland. For example, if croplands were abandoned, or reforestation took place, then the observed NDVI variability (amplitude) might decrease as natural vegetation becomes established. The NDVI and EVI were lower than their seven-year means in both northern and high-altitude biomes (namely (sub)nival snow/ice, boreal barren/sparsely vegetated land and forest, and cool temperate barren/sparsely vegetated, grassland and shrubland/woodland). Similarly, both VIs were highest for Mediterranean and warm temperate forests and lowest for (sub)nival snow/ice, and alpine and boreal barren/sparsely vegetated lands. Evergreen and deciduous vegetation types differ in their canopy cover and leaf longevity in that the former retains much of its canopy, thus appearing quite uniform throughout the year, whereas the latter sheds its leaves, thus changing its canopy cover widely between leaf-on and leaf-off periods. Therefore, the amplitude of the VI curves is expected to differentiate between evergreen (low amplitude) and deciduous (high amplitude) vegetation types. Both VIs showed that Mediterranean forest, where evergreen coniferous trees (e.g. _Pinus_) dominate, had the lowest amplitude throughout the entire period. Similarly, boreal forest with conifers (e.g. _Picea_ and _Abies_) had a pronounced bimodal growing