3.1 EP development mode
The histograms of the statistically significant short-term LEP, AEP, and
HEP trends (1999–2013) over the NH (Supplementary Fig. 1) were derived
(Fig. 2A–C, respectively). In the study period, for the whole NH the EP
of the three kinds of ecosystems all were increasing, wherein the LEP
and HEP ecosystems both showed weaker tendencies than the whole
ecosystems (the average LEP trend = 0.28 year-1, the
average AEP trend = 0.31 year-1, and the average HEP
trend = 0.29 year-1). Then, the histograms of the
statistically significant LEP, AEP, and HEP trends across the NA
(Supplementary Fig. 2) and NE (Supplementary Fig. 3) were also
generated. The EP strengthening tendencies over the NE were quite
approximate to those of the NH, merely being a little stronger for all
the three kinds of ecosystems (the average LEP trend = 0.32
year-1, the average AEP trend = 0.35
year-1, and the average HEP trend = 0.32
year-1); but for the NA, the EP strengthening
tendencies were much slighter and of a little difference in their
relative relation, i.e., the HEP ecosystems showed stronger tendencies
than the whole ecosystems (the average LEP trend = 0.13
year-1, the average AEP trend = 0.15
year-1, and the average HEP trend = 0.16
year-1). The results suggested that in the last decade
the terrestrial ecosystems over the NE were more prosperous than those
over the NA, in terms of productivity capacity increasing, and this
inference was briefly consistent with the findings in the earlier
studies (Piao et al., 2007; Kim et al., 2012). In
addition, the statistically significant snow-onset and -end SP trends
(2001–2014) over the NH were also derived (Supplementary Fig. 4), with
their characteristics quantitatively characterized.
-Insert Fig. 2 here-