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Figure 4.
Linear regression (with intercept forced to zero) between the simulated values of Gs in the
plot scale (Gs
P
') from the observed data on the pot scale (Gs obs) (a), simulated values of Gs in
watershed scale (Gs
B
") from observed data on the pot scale (Gs obs) (b) according to Qleaf.
4. Discussion
Many ecological studies are related to small spatial and temporal scales due to the easiness
of operation and better understanding of the interaction of factors [18]. Considering this
bias, the scaling up of information may constitute a useful tool for exploring upper scales
from inferior ones and vice-versa [31]. This procedure involves a gradual process in which
knowledge of how information is transferred from one scale to another is fundamental for
understanding the mechanisms responsible for the natural generating of a standard
phenomenon, which in turn are important for natural resource management. On the other
hand, the scaling up is made from a reductionist perspective based on the detection
mechanisms for determining the key processes operating at a certain level or scale, and its
subsequent extrapolation to a higher or lower scale than the one studied [23].
From this principle, we could see the correlation between ecophysiological variables E and
Gs with environmental variables Qleaf and VPD (Figure 2 and Table 3) in the three
developmental stages of the
Eucalyptus grandis x Eucalyptus urophylla
. The characterization of
the leaf behavior of E and Gs according to Qleaf and VPD from the pot scale to the
watershed scale, we observed a similar tendency of response, which facilitated the
extrapolation of the data from the pot scale to the plot/ or watershed scale in most relations,
except for
Gs = f (VPD)
.
The behavior pattern of E and Gs according to Qleaf as observed in this study (Figure 2a, 2b,
2c), is well found in the literature [19, 22], as well as pattern of
Gs = f (VPD)
for the pot scale
(Figure 2d). However, the almost linear response pattern of
Gs = f (VPD)
found in the plot
and watershed scales showed lower Gs in these situations even with increasing VPD. This
sharp difference in the tendency of response of
Gs = f (VPD)
between the scale pot with the
plot and watershed scales led to difficulty in adjusting the equations Gs
VP
, Gs
VB
and Gs
PB
(Table 7).
According to [39] and [48] there are numerous observations that Gs decreases in response to
an increase in VPD between the leaf and air. However, the plot and watershed scales, where
