Paired catchments
The four catchments are on the same geological formation, sandstone from
sedimentary rocks. The C1 catchment has 57.5% of its area under Rhodic
Hapludox and 42.5% under Typic Hapludox, the same soil found in more
than 95% of the area of the C2, C3 and C4 catchments. The catchments
have similar physiographic characteristics (Table 1).
The catchments have riparian vegetation [native vegetation]
preserved along the watercourses, with canopy of Eucalyptus
saligna and understory with native species characteristic of
semi-decidual seasonal forest in regeneration (Santos et al., 2019). The
area with native vegetation represents 8%, 48%, 13% and 44% of the
areas of the C1, C2, C3 and C4 catchments, respectively. The C1
catchment has a mosaic of forest plantations [forest mosaic] in 87%
of its area, C2 has 52% of its area in the process of native forest
restoration, and C3 and C4 have 80% and 50%, respectively, of their
areas with commercial eucalyptus forests [Eucalyptus plantation].
The C1 catchment is under a regrowth cycle that underwent clearcutting
in 1997 (Câmara & Lima, 1999). From harvest in 1997, the occupation of
the catchment has been diversified with different species ofEucalyptus spp. , at different ages, in addition to planted
forests of Pinus spp. , Araucaria angustifolia andAcacia mangium , in a smaller proportion, forming a forest mosaic
of species and ages [forest mosaic].
The C2, C3 and C4 catchments were covered by clonal Eucalyptus
plantations, under forest management in a short cycle (< 7
years) with conduction of regrowth. This management system was
implemented more than 30 years ago in the area, with replanting of the
plantations, on average, every 14 years. After the harvest in 2014,
there was regrowth of the plantation without conduction, leading to a
new clearcut in 2016 in the C2 and C3 catchments. In C2, after the
clearcut of 2016, a native forest restoration process began in the area
initially occupied by planted forests [eucalyptus plantation]; while
in the C3 catchment there was the replanting of eucalyptus plantations.
In the C4 catchment there was the conduction of the regrowth
[eucalyptus coppice], initiated after the 2014 harvest.
C2 and C3 had their areas replanted in 2016. The forestry practices
adopted in the implementation included the monitoring and control of
leaf-cutting ants using granulated bait; control of invasive plants with
chemical and manual weeding; application of dolomitic limestone in total
area; subsoiling with agricultural tractor; manual planting of
seedlings; basal and top-dressing fertilization with NPK; manual
application of pre-emergent herbicide in the planting row and replanting
of gaps.