Chemistry Reference
In-Depth Information
A fundamental aspect of ecological processes is that they are affected by spatial and
temporal dimensions. In spatial terms, for example, measurements made on a leaf in terms
of net primary productivity, can not be extrapolated directly to the tree, because for this
extrapolation it is necessary knowledge about the distribution of the canopy, the
arrangement of leaves, availability of soil water etc. Likewise, the extrapolation to the forest
and the ecosystem needs information previously dispensable in smaller scales. This study
focused on all measurements, only fully expanded leaves and fully disposed to incident
radiation. In fact, we know that there is no way to expand these results to an already formed
canopy, since in this case, the leaves do not have a uniform development, as well as
variation in the incidence of radiation and, thus, there is a need for additional data that were
not addressed in this study. However, tendencies were observed and simulated by the
models developed. This notion of scales and their extrapolations are essential to avoid
mistaken views and phenomena in a certain scale to larger or smaller scales. As a scale is
broadened, most interactions occur between the growing number of compartments of the
system, making it more difficult and laborious studies of cause-effect relationships from
models based on processes.
Adding to the complexity of understanding the interactions between the ecophysiological
variables, there is also the difficulty of the experimental protocol. This fact reinforces the
merits of the methodology presented here. As stated by [21] in order to generate practical
tools, such calculations based on processes must be combined with empirical relations
derived from experiments and measurements carried out over several periods.
5. Conclusions
The relations between E and Gs with Qleaf and VPD showed significant differences at 1 or
5% in all relations of scaling up, except for the relation E x VPD in scaling up of plot /
watershed, and Gs x VPD pot / watershed. The relation that had the best response between
E and Gs and environmental variables was E / Qleaf whose correlation was significant on all
scales at 1 or 5%. The measured values of E and Gs were consistently above the plot and
watershed scales compared to the pot scale. For each lower scale, a model was developed
for scaling up into a higher scale. It was possible to perform the scaling up (pot, plot
andwatershed scale) of E and Gs. The simulation models of E according to Qleaf / VPD and
Gs and Qleaf / VPD proved robust in each of the scales. There was no need to adjust the
models of scaling up between plot and watershed in relations involving E and Qleaf, and E
and VPD. All results were obtained for Ψ
pd
between 0 to -0.5 MPa. It is suggested that
measurements of E and Gs are carried out in three scales in others Ψ
pd
to confirm the
findings of this study.
Author details
Kelly Cristina Tonello
Federal University of São Carlos, Departament of Environmental Science, Forest Engineering,
Rod. João Leme dos Santos, km 110, Itinga, Sorocaba-SP, Brazil
