Chemistry Reference
In-Depth Information
the watershed is called a relief of hills, dominated local amplitude 100-300 m and slopes of
medium to high - above 15%, with high drainage density, closed to open valleys and alluvial
plains inland restricted [16]. The soil of the plot of interest is the type Tb dystrophic
Cambisol, Oxisols with clay. For monitoring the ecophysiological behavior, measurements
were carried out in a stand of
Eucalyptus grandis
x
Eucalyptus urophylla
, 60 months after
planting in 3 x 2 m spacing with the aid of a platform lift with a range of 18 meters in height
(Figure 1c). Monitoring ecophysiological transpiration, stomatal conductance, leaf water
potential, photosynthetic active radiation and vapor pressure deficit atmospheric were held
throughout the month of August 2008.
(a) (b) (c)
Figure 1.
Scales: (a) Pot scale, (b) Plot scale and (c) Watershed scale: lift platform for observation of the
variables used in ecophysiological clonal plantations of Santa Marta Farm, Igaratá-SP, Brazil.
2.1. Ecophysiological variables
The observations of water availability in the soil were performed by measuring predawn
leaf water potential (Ψ
pd
) using a Scholander pressure chamber [38], model 3035 (Soil
Moisture Equipment Corp.., USA) before sunrise in healthy leaves fully expanded.
According to [45], Ψ
pd
maintains a balanced relationship with the substrate's water
potential, due to low rates of transpiration by plants presented overnight. To do so, four
branches per seedling (on pot scale) or tree (on plot and watershed scales) were collected
simultaneously. The measurements were carried out immediately after material collection.
Physiological measurements of transpiration (E) and stomatal conductance (Gs) were made
by infrared gas analyzer (IRGA) LC-PRO + (ADC bioscientific Ltda., UK). For this end, four
randomly and fully expanded healthy leaves for each individual seedlings/tree were chosen.
The readings were held at hourly intervals throughout the day in the period from 8:00 am to
5:00 pm.
2.2. Environmental variables
Environmental variables such as photosynthetically active radiation and vapor pressure
deficit of the atmosphere were chosen to correlate with the E and Gs. The PAR on the leaf
