Agroforestry
Solutions for
Rehabilitating
Abandoned Pasture
Land in the Brazilian
Amazon
Research Site
Characteristics
Location
The
study site is
located at the
EMBRAPA-CPAA pasture
research station,
54 km north of
Manaus on the
road BR 174 to
Boa Vista at 02
31' 04 S",
60 01' 48"
W. The site is
characterized
by rolling topography
(20-60m.a.s.l.)
with plateaus
and small valleys.
The dominant vegetation
at the site is
moist, evergreen
forest.
| Click
on a link
to see a photo
of the research
site. |
| Manaus,
Rio Negro
& Amazonas
|
BR
174 (1991) |
Pastures
on BR 174
(1992) |
| Pastures
on BR 174
(1993) |
Roadside
vegetation |
Degraded
pasture |
| BR
174 (1994) |
BR
174 (1995) |
|
Soil
and rainfall at
the study site
The
soils are classified
as isohyperthermic
clayey kaolinitic
Hapludox (US Soil
Taxonomy) and
contain around
85% clay.
| Soil
Depth |
ECEC |
Base
Sat. |
Al
Sat. |
pH |
C |
N |
Extract.
P |
Total
P |
Ca |
Mg |
K |
| (cm) |
cmol(+)/kg |
% |
|
% |
mg/kg |
cmol(+)/kg |
| Pre-Burn |
| 0-15 |
2.52 |
50.36 |
49.64 |
4.30 |
2.64 |
0.20 |
2.50 |
100 |
0.89 |
0.32 |
0.09 |
| 15-30 |
1.94 |
41.81 |
58.19 |
4.31 |
1.65 |
0.13 |
1.19 |
81 |
0.55 |
0.21 |
0.05 |
| 30-45 |
1.59 |
34.18 |
65.82 |
4.30 |
1.16 |
0.09 |
1.03 |
70 |
0.37 |
0.14 |
0.03 |
| Post-Burn |
| 0-15 |
2.56 |
53.53 |
46.72 |
4.33 |
2.57 |
0.20 |
1.86 |
100 |
0.94 |
0.03 |
0.12 |
| 15-30 |
2.02 |
45.29 |
54.71 |
4.25 |
1.72 |
0.13 |
1.50 |
81 |
0.60 |
0.25 |
0.08 |
| 30-45 |
1.70 |
38.00 |
62.00 |
4.30 |
1.20 |
0.10 |
1.25 |
70 |
0.42 |
0.17 |
0.06 |
Climate
The
mean annual rainfall
is 2,700 mm with
a two month dry
season (July and
August). and the
mean annual rainfall
is around 2,800
mm with a dry
season lasting
from June to September.
The mean monthly
rainfall at the
start of the experiment
(November 1991
and first six
months of 1992)
was significantly
lower than average
(Fig.
1).
Vegetation
The
dominant vegetation
at the site is
moist, evergreen
forest. Higuchi
et al (XXXX) have
described the
species composition
and estimated
the phytomass
of the local primary
forest.
The
degraded and abandoned
pasture vegetation
consists of 39
species representing
34 genera and
23 families. The
most abundant
tree species were
Laetia procera,
Vismia amazonica,
Vismia lateriflora,
and Vismia cayennensis.
The most frequently
encountered herbaceous
species were the
competitive forbs
Borreria verticillata
and Rolandra fruticosa.
Many of the species
and genera detected
at this site have
been reported
in species inventories
of abandoned pastures
at other locations
in the Amazon.
Total aboveground
biomass on the
abandoned pastures
corresponds to
about 5% of the
biomass reported
for primary forests
on Oxisols in
the Amazon and
less than half
of that reported
for other secondary
forest regrowth
of similar age.
This is a reflection
of moderate to
high site disturbance
intensity, which
hinders forest
re growth when
the pastures were
abandoned (McKerrow,
1992).
Previous
land use and the
current vegetation
at the study site
The
primary forest
on the site was
slashed and burned
in 1976 and annual
crops (rice, cassava)
grown until 1978.
From 1978-1984,
pastures were
established and
actively grazed
for 4 to 6 years
before being abandoned.
Table 2 details
the sequence of
activites leading
up to the establishment
of the agroforestry
prototype systems.
