Tropentag 2012
Universities of Göttingen and Kassel/Witzenhausen
Göttingen, September 19 - 21, 2012
Resilience of agricultural systems against crisis
Floristic composition of soil seed banks in degraded pastures recovered by forest
plantations in the Eastern Amazon, Brazil
Julie Andrews de França e Silva¹; Cecília Hernandez Ochoa Coutinho²; Sílvio Brienza
Júnior³; Vanessa Gomes de Sousa4
¹ PET Scholarship / University Federal Rural of Amazônia, Forest Engineering;
Embrapa Eastern Amazon, Belém, Pará, Brazil. Email: [email protected]
² Scholarship INCT/CNPq/ Museum Paraense Emílio Goeldi/Embrapa Eastern Amazon.
[email protected]
³ Embrapa Eastern Amazon, Belém, Pará, Brazil. Email: [email protected]
4
Scolarship – Projet Rede Biomassa. [email protected]
Introduction
The northeast Pará has the biggest alteration stage of original landscapes, resulting from
the productive system to slash and burn for agricultural cultivation with short fallow
periods, and their colonization process (Oliveira et al., 2006).
The evaluation of the soil seed bank is important for the process of natural regeneration
in degraded areas, since the characterization of the richness and density of species is
essential to define ways to restore (Calegari, 2009).
The soil seed bank is formed and renewed by means of biotic processes (dispersal by
animals) and abiotic (wind and water) (SCHMITZ, 1992). Is a dispersion system cyclic,
and may be transitory with viable seeds for one year or persistent with viable seeds in
the soil for more than one year (Nobrega et al. 2009).
The objective of this study was to evaluate the floristic composition of the soil seed
bank present in the understory of mixed of forest species plantation in degraded
grassland in the municipalities of Bragança, Capitão Poço and Garrafão do Norte,
proposed for recovering of Legal Reserve Areas (LRA).
Material and Methods
This work was carried out by Embrapa Eastern Amazon partnership with Project
Inovagri and the Brazilian Cooperation Agency - ABC, with support and financing from
the International Tropical Timber Organization - ITTO.
The soil seed bank was collected in four units recovery of degraded areas which were
installed three types of forest productive arrangements in degraded pastures. From each
site were collected six soil samples of seed bank, which were mixed to compose one
sample, resulting in four composite samples in each unit of recovery, totalizing 16
composite samples.
The soil samples were collected using a wood guide measuring 0.5 m x 0.5 m (0.25 m²)
at a depth of five cm. After collecting and packaging in plastic bags, the samples were
transported to a house in a green Embrapa Eastern Amazon.
The collected material was distributed in polyethylene trays and arranged randomly
inside a green house. The experiment was monitored daily for nine months, including
irrigation when necessary.
The seedlings were identified and identified according to: life habits (tree, shrub,
herbaceous, vine and palms), environmental groups was classified in pioneers, initial
secondary, late secondary and climax; and types of dispersion (anemochoric,
autochoric, barochoric, hydrochoric and zoochoric). The data obtained were saved in
EXCEL spreadsheets for statistical analysis.
Results and Discussion
After nine months were accounted a total of 6,141 seedlings. In the three municipalities
of northeast Pará, there was a predominance of herbaceous vegetation (herbaceous vines
and herbaceous) with more than 71%, while the woody vegetation (tree, shrub and
woody vine) ranged from 19 to 29% (Figure 1), the pioneer species were more abundant
with more than 57% (Figure 2).
Figure 1: Distribution of species
according to life habit.
Figure 2: Distribution of species
types of dispersion.
The large amount of herbaceous species present in the soil seed bank may be related to
the short life cycle, high productivity of seed and the low soil cover, which favors a
higher incidence of sunlight and canopy openness, the seed dispersal is facilitated
(PEREIRA; ALVARENGA and Botelho, 2010).
The predominancy of pioneer species has been observed in studies of soil seed bank in
pastures areas (COSTALONGA, 2006; MIRANDA NETO et al., 2010). This result
contributes to forest restoration, since in a few years the vegetation can be replaced by
other species more advanced stages of succession (MIRANDA NETO et al., 2010). The
initial phase of the species germinate easily and collaborate with the establishment of
other species, as well as improved soil fertility and provides favorable conditions for the
recruitment of other species (SHERER, 2004).
Tabela 1: List of families and species most representative of the municipalities
of Bragança, Capitão Poço and Garrafão do Norte, northeast Pará.
Families
Municipalities
Individuals
Total
Most
representatitive
Species
%
Total
Most
representatitive
%
Bragança
1.282
Capitão Poço
Garrafão do
Norte
1.260
3.599
22
16
22
Cyperaceae
Rubiaceae
Poaceae
Verbenaceae
Phyllanthaceae
Rubiaceae
Cyperaceae
Poaceae
Fabaceae
Euphorbiaceae
Cyperaceae
Poaceae
Phyllanthaceae
Rubiaceae
Nyctaginaceae
39,24
33,07
10,45
3,04
2,65
47,38
34,37
7,54
5,40
1,03
65,05
11,42
6,42
4,92
4,00
51
36
57
Borreria verticillata
(L.) G. Mey.
Dichromena ciliata
J. Presl & C. Presl
Cyperus haspan
Rottb.
Fimbristylis
miliacea (L.) Vahl
Borreria latifolia
(Aubl.) K. Schum.
Borreria verticillata (L.)
G. Mey.
Dichromena ciliata J.
Presl & C. Presl
Cyperus surinamensis
Rottb.
Cyperus haspan Rottb.
Mimosa sensitiva L.
26,29
Cyperus haspan Rottb.
Cyperus surinamensis
Rottb.
Dichromena ciliata J.
Presl & C. Presl
Cyperus diffusus Vahl
Phyllanthus niruri L.
20,90
16,56
The results of the floristic composition of the soil seed bank, it may have been,
according to Araújo et al. (2001), influence the type and intensity of previous land use,
which implicates the way is the natural recovery of the ecosystem.
In the municipalities of Bragança, Capitão Poço and Garrafão do Norte, species with
seed dispersal barochory was the most representative ranging from 39 to 44%, followed
by the dispersal of propagules anemochoric that ranged from 22 to 29%.
Figure 3: Distribution of species according to types of dispersion.
Conclusions and Outlook
21,14
6,24
5,46
4,45
44,05
14,37
7,62
6,35
3,73
15,42
11,81
5,89
The soil seed bank in the areas studied there was a predominance of pioneer species and
herbaceous, which indicates the occurrence of forest restoration process, since it
presents good floristic composition and forest structure, with the presence of species of
all successional stages. The installed forest productive arrangements in pastures areas
has as objective the rehabilitation processes and ecological functions. Thus, forest
production systems implanted have the recomposition potential of Legal Reserve Area.
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