TEMPORAL ANALYSIS OF FOREST FRAGMENTATION ON THE BOA
ESPERANÇA RIVER BASIN IN NOVA FRIBURGO MUNICIPALITY - RIO DE
JANEIRO STATE - BRAZIL
Luana Balbino dos Santos
Master - LAGESOLOS - Universidade Federal do Rio de Janeiro - Email: luanabs.ufrj@gmail.com
Antônio José Teixeira Guerra
Ph.D – LAGESOLOS – Universidade Federal do Rio de Janeiro - Email: antoniotguerra@gmail.com
www.lagesolos.ufrj.br
Abstract
To explore natural resources respecting the environmental weaknesses, it is necessary to
understand the dynamic processes that involve the relationships of the various elements of
nature. The different forms of management, which cause various degrees of environmental
impacts, as forest fragmentation, cause changes in the structure and composition of forest
remnants threatening its functionality. Forest remnants constantly threatened by human action
have as a result of fragmentation, different successional stages that reflect differences in their
structure and floristic composition, nutrient cycling processes and soil physical and chemical
properties that are good indicators of the degree of interference in the system, providing
information about the integrity of these ecosystems. This paper has as object of study the
Atlantic Forest fragments, inserted into the Boa Esperança river basin (Nova Friburgo
Municipality – Rio de Janeiro State) and the objective of this study is to analyze the evolution of
forest fragmentation on the Boa Esperança basin, over 15 years, and understand the stage where
such
forest
remnants
through
physic-chemical
properties
of
soils
To identify if the functionality of the forest systems were threatened, soil physical and chemical
properties, such as bulk density, porosity, texture, organic matter and pH have been examined.
In each fragment samples were collected along a transect. The transect was established from 15
meters from the edge of the fragment, to avoid a possible edge effect, and soil sampling was made
every 10 meters. Soils were collected in three forest remnants with different characteristics: a
fragment of approximately 176 hectares, a fragment of approximately 64 hectares, and a forest
remnant that does not configure an isolated fragment, because its vegetation connects with the
Atlantic Forest. After laboratory analyses statistical analysis were carried out. As a result, it was
observed that the forest remnant that is not isolated presents features less susceptible to erosion
and a better integrity of forest system and that over fifteen years, there has been a significant
reduction of forest at Boa Esperança basin. It was concluded that even though they are located in
the same area, the forest fragments are subject to different impacts, depending where the
fragment is inserted, the degree of isolation and how much they are subject to anthropogenic
activities, which reinforce the importance of environmental protection area.
Introduction
To explore natural resources respecting the environmental weaknesses, it is necessary to
understand the dynamic processes that involve the relationships of the various elements of nature. The
different forms of management, which cause various degrees of environmental impacts as forest
fragmentation, cause changes in the structure and composition of forest remnants threatening its
functionality. Viana (1990) defines forest fragment as any area of natural vegetation, continuous
barriers interrupted by human able to significantly decrease the flow of animals, pollen and/or seeds.
Forest fragmentation triggers a series of changes in the landscape, including disturbances in the
water regime and modifications to the internal dynamics of ecosystems. Therefore, forest remnants
constantly threatened by human action, presents various successional stages, reflecting in changes on
structure, floristic composition, nutrient cycling processes and soil physical and chemical properties,
which makes these features good indicators of the degree of human interference in the forest, providing
information about its integrity. Therefore, it is important to understand the impact of different
management on ecosystem, enabling conservation measures and/or recovery.
This way, the aim of this study is to analyze the evolution of forest fragmentation on the Boa
Esperança river basin over fifteen years, and to analyze the integrity of this forest fragments through
its physical and chemical soil properties.
Study area
The study area comprises forest remnants in different stages of regeneration and degrees of
isolation, inserted on the Boa Esperança river basin. This basin has approximately 52.8 km², is located
in Macaé river basin and it is located within the limits of the environmental protection area of Macaé de
Cima. In this region, the vegetation cover is classified by Rizzini (1979) as predominantly Atlantic
Montana Rainforest type. According to the map made by EMBRAPA in the 1: 250.000 scale, in 2003,
there was a predominance of cambisoils, that according to Lepsch (2002), are very susceptible to soil
erosion. Currently, the Boa Esperança river basin has its soils predominantly occupied by farmers and
tourism enterprise, which can represent a threat to forest remnants.
The bedrock of the region is formed basically by intrusive rocks and metamorphic Pre-Cambrian
skimming extensively in much of the area, belonging to the lito-estratigraphic unit called Paraíba do
Sul Complex (Silva, 2002). Geomorphological aspects resulting from the geological evolution of the
region were responsible for the local relief. Dantas (2001) describes the morpho-escultural unit as
Morpho-escultural Escarpment Mountain Basin. According to the author, the area presents geological
morfo-estructural folds, which resulted in a basement complex, with structural, tectonics and
lithological diversity.
In the study area the climate is classified as tropical altitude, with averages ranging between 18°C
in the winter to 24° C in the summer. In the higher parts of the catchment area are high rates of rainfall
up to 2000 mm per year and over 500 mm per month, as recorded in the year 2010, by the Brazil
national agency of waters at Galdinópolis rainfall station in Nova Friburgo.
Picture 1 - Location map of forest fragments studied in Boa Esperança river basin.
Picture 2 - Forest fragments and pasture in Macaé river basin (Luana Balbino, 2009).
Methodology
To perform analysis of temporal fragments based on land use, was done a mapping of forest
fragments from a scene from Alos image (Sensor AVNIR-2), imaged in April 18, 2009 and a Landsat
image, imaged in October 1994. The Alos sensor has four spectral bands and spatial resolution of 10 m
and 8 bit. The Landsat has spatial resolution of 30 m, seven spectral bands and radiometric resolution
of 8 bits. The mapping was made through the SPRING and ARCGIS 9.3 software 5.1 both on the scale
of 1.50.000, aiming to map forest fragments over 15 years and to realize if there is an advancement of
forest fragmentation.
According to the Technical Manual of land use from IBGE (2006), the land use survey and cover
indicates the geographical distribution of the usage typology, identified through homogeneous patterns
of land cover, being of great benefit to the updated knowledge of the forms of use and settlement of
space, constituting important planning tool and guidance to decision making.
For the mapping, a semi-automatic classification was held in SPRING 5.1, where the user
participates actively, making corrections and reducing potential errors. Before the sorting was done a
training, and the segmentation of the image. In the segmentation the image was divided into regions
that present certain similarities and that correspond to areas of interest in the application. Thus, each
pixel is labeled as a distinct region and a similarity criterion is calculated for each pair of adjacent
regions, indicating how much two spatially regions are similar. In addition, the area was assigned a
value, which corresponds to the value of minimum area in number of pixel data, so that a region is
individualized in the case of the study, the similarity value was 15 and the area value was 20. The
classes of land user in this study were: Forest, urban, rocky outcrop, agriculture and livestock use,
according to the IBGE (2006).
To analyse such forest systems has their functionality threatened, were examined the soil
physical and chemical properties, such as mineral density, bulk density, porosity, texture, organic
matter and pH, all in accordance with the methodology proposed by EMBRAPA (1997). In each
fragment six soil sample collections were made, on soil surface (0-20 cm), along a transect of 50 m in
length. The transect was established 15 meters from the edge of the fragment, to avoid possible edge
effects, and the collections were made every 10 meters in length.
Soil analyzed were collected in three forest remnants with different characteristics: a fragment of
about 176 hectares (Picture 1 - Fragment 3), which is the larger fragment and for its located along the
road that connects the São Pedro da Serra district and Boa Esperança, it is apparently more degraded
and has more evidence of human activity. The other one is a minor forest fragment (Picture 1 Fragment 1), with about 64 hectares, a more regular format, and therefore with lower edge area, located
in the urban area of Lumiar district. And was also used a forest remnant (Picture 1 - Fragment 2) in
north of the Boa Esperança river basin, which unlike other fragments is not an area of vegetation
isolated, and connects with other local Atlantic Rainforest remnants, suggesting a better preservation
state.
Results
Forest Fragmentation
In a first analysis we can observe a reduction of forest cover and increasing of forest
fragmentation over the past 15 years, which is in line with the historical process of the region, guided
by the advancement of agriculture, pastures and tourism areas. This increase can be noticed when
observing the land use maps for the periods in question (Figure 4 and 5). In this analyses is notable an
advancement of urban area and farming. When analyzing the forest cover in the year 1994 was found
forest coverage, including all succession stages, about 44.48 km², while in 2009 the forest cover
matches is about 42.60 km², which means a reduction of 3% of forest area in just 15 years. Changes
can be noticed also for the urban area, which increased from 1.13 km² to 2.41 km², as well as for the
anthropic agricultural use areas, which increased from 8.9 km² to 8.58 km². All values and their
respective percentages can be seen in Table 1, below.
According to Rambaldi (2003) and Bohrer and Barros (2006) these advances are resulting from
the population increase in recent decades, by the expansion of areas targeted for agriculture and/or
extraction of plant resources, without proper management on the steep slopes and, which leads to
increased deforestation and intensification of erosion processes in the region.
Table 1 – Land cover in kilometers and percentage for the two examined periods.
1994
Use Land Classes
Anthropic
Forest
Rocky outcrop
Urban
2009
Area
Km²
8.59
44.48
1.31
1.14
%
15.47
80.12
2.36
2.05
Use Land Classes
Anthropic
Forest
Rocky outcrop
Urban
Shadow
Area
Km²
8.95
42.65
1.31
2.42
0.17
%
16.13
76.84
2.36
4.36
0.31
Picture 3 - Land use of Boa Esperança river basin for the year 1994.
Picture 4- Land use of Boa Esperança river basin for the year 2009.
Soil Characteristics
In relation to soil texture, there were variations between the fragments and within the fragment
itself. The soil texture Fragment 1 presents as loam, sandy loam and sand clay loam soil. In the
fragment 1, it is possible to see that the sand fraction is prevalent in almost all points, reaching 68.62%
(Table 2). It must be pointed out, that low values of clay added to high values of silt make the soil more
susceptible to erosion, especially in soils exposed (Guerra, 2005). In the Fragment 2 soils have mostly a
loam texture, with few points showing sandy clay loam and clay loam. We notice that in this fragment
clay values exceed the 20% (Table 3). Clay is an important component of soil, because adequate soil
texture in addition to other features, such as organic matter content, providing a better soil stability.
The Fragment 3 presented at any point of collection and in the two periods analyzed a sandy loam soil
texture. In these soils, there was a greater sand fraction when compared to the other fragments (Table
4).
In relation to the level of acidity, all samples in the three fragments had pH values close to 4,
which features acid soil and without significant differences between them (Tables 2, 3 and 4) in
relation to the values of porosity, all points tested, in the three fragments, had values above 50%, which
indicates a high porosity of the soil. The fragment with the greatest values was the fragment 2, which
featured the highest average (60.12%).
Therefore, soils that exhibit the best water drainage, and are less prone to runoff are the soils of
the Fragment 2, which have greater porosity. It is important to note that the values of porosity, as well
as the values of bulk density and real density must be taken into consideration along with other soil
characteristics, such as the values of organic matter and particle size distribution (MORGAN, 2005;
GUERRA, 2007).
It is important to accentuate that in the Fragments 1 and 3, the average values of organic matter
were close to 3%, which according to Selby (1993), Lepsch (2002) and Morgan (2005) are values that
provide a good stability to aggregates. While the Fragment 2 presented high values of organic matter,
above 5%, mainly in the highest points of the hillside that corresponding to the points 12A, 12B, 13A,
13B, 14A and 14B ( Table, 2, 3 and 4).
When comparing the values of organic matter found in a fragment with the other, it appears that
the Fragment 1 and 3 do not differ significantly (p-value > 0.05), which is visible when looking at the
values of their medium. However, the Fragment 2 differs significantly to be compared with the
Fragments 1 and 3 (p-value < 0.05). These differences when comparing the fragments can be evidenced
through the analysis of the boxplot (Picture 5). It is likely that the difference in values of organic matter
to Fragment 2 be related to the better preservation of the forest, which leads to a better cycling of
nutrients that reflects in a more stable and balanced ambience, if we take into account other features
already discussed.
Teste de Comparação das
Médias
p-valor
Fragmento
1
Fragmento
2
<0.05
Fragmento
2
Fragmento
3
<0.05
Fragmento
1
Fragmento
3
>0.05
Picture 5 - Boxplot about organic matter for the three fragments analyzed.
Table 2 – Soil analysis results to Fragment 1, n: samples number.
Fragment 1
Matter
Organic (%)
1A
1B
2A
2B
3A
3B
4A
4B
5A
5B
6A
6B
7A
7B
Medium
Standard deviation
Máximum
Mínimum
n
pH
KCl
2.21
1.97
1.40
1.79
1.55
2.57
1.74
1.78
3.28
1.98
2.07
2.69
2.67
2.66
2.17
0.53
3.28
1.40
14
Water
4.15
3.92
3.90
4.00
3.79
3.78
3.72
3.84
3.94
4.01
3.85
3.74
3.83
3.75
3.87
0.12
4.15
3.72
14
4.50
4.53
3.80
3.89
3.98
4.13
4.01
4.34
4.42
4.48
4.08
4.16
4.10
4.15
4.18
0.23
4.53
3.80
14
Sand
52.63
68.62
56.31
50.51
55.99
59.11
55.34
58.99
63.87
60.36
55.35
61.62
40.74
62.24
57.26
6.69
68.62
40.74
14
Texture
Silt
22.07
14.18
21.29
27.19
20.62
20.59
24.96
19.71
17.44
17.35
22.66
18.68
41.76
16.96
21.82
6.66
41.76
14.18
14
Bulk Density
(g/cm³)
Clay
25.30
17.20
22.40
22.30
23.40
20.30
19.70
21.30
18.70
22.30
22.00
19.70
17.50
20.80
20.92
2.26
25.30
17.20
14
1.09
1.07
1.17
1.11
1.13
1.13
1.12
1.15
1.08
1.19
1.22
1.12
1.15
1.27
1.14
0.06
1.27
1.07
14
Real
Density
(g/cm³)
2.47
2.56
2.50
2.54
2.35
2.41
2.44
2.50
2.60
2.50
2.42
2.35
2.25
2.38
2.45
0.10
2.60
2.25
14
Porosity
(%)
55.86
58.27
53.20
46.17
40.68
53.11
54.08
54.00
58.42
52.40
37.17
52.40
48.83
46.66
50.80
6.25
58.42
37.17
14
Table 3 - Soil analysis results to Fragment 2, n: samples number.
Fragment 2
8A
8B
9A
9B
10A
10B
11A
11B
12A
12B
13A
13B
14A
14B
Medium
Standard deviation
Máximum
Mínimum
n
Matter
Organic (%)
2.45
3.19
3.91
4.79
4.33
4.43
4.07
3.97
6.47
5.74
5.34
5.50
6.59
4.97
4.70
1.18
6.59
2.45
14
KCl
3.76
3.83
3.85
3.90
3.15
4.02
3.81
3.81
3.92
3.99
3.81
3.78
3.76
3.78
3.80
0.20
4.02
3.15
14
pH
Water
4.20
4.01
3.88
4.45
3.90
4.59
4.07
4.07
4.33
4.52
3.85
3.80
3.90
3.89
4.10
0.27
4.59
3.80
14
Sand
39.20
51.89
45.31
44.08
34.55
46.10
41.21
38.10
49.76
62.48
47.49
48.09
43.65
34.22
44.72
7.42
62.48
34.22
14
Texture
Silt
34.41
29.21
33.30
24.12
39.96
28.71
38.60
34.60
30.34
15.22
27.51
24.81
30.26
32.38
30.24
6.31
39.96
15.22
14
Clay
26.40
18.90
21.40
31.80
25.50
25.20
20.20
27.30
19.90
22.30
25.00
27.10
26.10
33.40
25.04
4.26
33.40
18.90
14
Bulk Density
(g/cm³)
1.06
1.00
1.02
0.83
0.97
0.99
0.99
1.03
0.88
0.86
0.83
0.86
0.88
0.86
0.93
0.08
1.06
0.83
14
Real Density
(g/cm³)
2.27
2.25
2.33
2.35
2.38
2.50
2.35
2.35
2.44
2.44
2.63
2.50
2.44
2.27
2.39
0.11
2.63
2.25
14
Porosity
(%)
53.36
53.50
53.08
64.73
59.26
60.40
57.93
56.23
63.92
64.74
68.46
60.01
63.92
62.16
60.12
4.84
68.46
53.08
14
Table 4 – Soil analysis results to Fragment 3, n: samples number.
Fragment 3
15A
15B
16A
16B
17A
17B
18A
18B
19A
19B
20A
20B
21A
21B
Medium
Standard deviation
Máximum
Mínimum
n
Matter
Organic (%)
3.71
2.34
2.03
2.72
2.10
1.98
2.84
3.36
2.26
2.14
2.28
3.55
3.88
3.67
2.78
0.71
3.88
1.98
14
pH
KCl
3.70
3.62
4.06
3.70
3.85
4.07
3.92
3.75
3.79
3.78
3.88
3.89
3.78
3.96
3.84
0.13
4.07
3.62
14
Water
4.36
4.27
4.81
4.48
4.66
4.88
4.41
4.18
4.41
4.43
4.61
4.76
4.31
4.45
4.50
0.21
4.88
4.18
14
Sand
Texture
Silt
Clay
56.69
54.79
70.15
66.37
59.53
65.70
61.39
62.34
63.15
62.54
68.86
64.84
64.98
59.40
62.91
4.36
70.15
54.79
14
24.61
25.71
20.55
21.33
22.07
19.91
24.71
20.76
25.95
27.16
16.65
20.26
17.53
20.31
21.96
3.20
27.16
16.65
14
18.70
19.50
9.30
12.30
18.40
14.40
13.90
16.90
10.90
10.30
14.50
14.90
17.50
20.30
15.13
3.55
20.30
9.30
14
Bulk Density
(g/cm³)
Real Density
(g/cm³)
0.97
1.07
1.07
1.18
1.14
1.09
1.14
1.17
1.13
1.19
1.19
1.10
1.13
1.30
1.13
0.08
1.30
0.97
14
2.44
2.47
2.41
2.27
2.56
2.50
2.50
2.50
2.56
2.50
2.35
2.35
2.46
2.50
2.46
0.08
2.56
2.27
14
Porosity
(%)
60.23
56.67
55.60
48.08
55.54
56.40
54.40
53.20
55.93
52.40
49.43
53.25
39.55
48.00
52.76
5.14
60.23
39.55
14
Conclusions
The results showed that isolated forest fragments, more subject to human activity and smaller
(Fragment 1 and 3), have characteristics that make their soils more susceptible to erosion, as well as
other characteristics that compromise the environmental system functionality, such as soil erodibility
and vegetation characteristics. While, the forest remnant connected (Fragment 2) presented more
balanced environmental conditions.
It was clear in this study, which despite being analyzed fragments within the same basin and very
close to each other, the three fragments present characteristics that make their well distinct and with
different degrees of integrity that vary in function of local variants which these forests are subjected,
such as the matrix to which they are inserted, the size and shape of the fragment, the natural
characteristics, and mainly how are subject to the impacts resulting from human activity.
It is valid to note that these fragments are inserted in an area of environmental protection
(Environmental Protection Area of Macaé de Cima), which aims the preservation and maintenance of
the remnants of Atlantic Rain Forest, and so to ensure the conservation of these systems becomes even
more important to the creation of forest corridors in the region, thereby, the connection between the
fragments, plus your protection, reducing their isolation and possible edge effects.
With regard to this work, it becomes apparent the importance of remote sensing tools in
environmental analysis and that it becomes interesting to extrapolate this analysis to the entire area of
APA of Macaé de Cima, this research work is already being held at LAGESOLOS (UFRJ) in a
research work on Geomorphological Dynamics system project-Slope River basin plain in Macaé (RJ).
Therefore, it is concluded that despite the Boa Esperança river basin be inserted within the limits of an
environmental protection area, its forest remnants are threatened, mainly by increasing human pressure.
Bibliography
BOHRER, C. B. A.; BARROS, F. A. Proteção e Restauração da área do entorno do Parque Estadual
dos Três Picos. REBRAF, Nova Friburgo, Rio de Janeiro, p.45, 2006.
DANTAS, M.E. (2001) Mapa geomorfológico de Macaé. Brasília: CPRM. Escala 1:250.000,
CD-ROM.
EMBRAPA. Centro Nacional de Pesquisa de Solos. Manual de Métodos de Análise de Solo. Ministério
da Agricultura e do Abastecimento, 2. ed. rev. Atual, Rio de Janeiro, 212p, 1997.
GUERRA, A. J. T. Processos Erosivos nas encostas. In: Geomorfologia – Uma atualização de Bases e
Conceitos. GUERRA, A. J. T.; CUNHA, S. B., Editora Bertrand Brasil, Rio de Janeiro. 7ª edição,
p.149-209, 2007.
GUERRA, A. J. T Processos Erosivos nas encostas, In: GUERRA, A. J. T.; SILVA, A. S.;
BOTELHO, R. G. M. Erosão e conservação dos solos: conceitos, técnicas e aplicações. Rio de
Janeiro, Bertrand Brasil, 2005.
INSTITUTO BRASILEIRO DE GEOGRAFIA E ESTATÍSTICA (IBGE) (2006). Manual
técnico de uso da terra. Rio de Janeiro,2ª edição, 91p.
LEPSCH, I. F. Formação e conservação dos solos. São Paulo, Oficina de Textos, p.178, 2002.
MORGAN, R. P. C. Soil erosion and conservation, 3ª edição, Blackwell, London, p.303, 2005.
RAMBALDI, D. M. A Reserva da Biosfera na Mata Atlântica do Estado do Rio de Janeiro. Conselho
Nacional da Reserva da Biosfera na Mata Atlântica, São Paulo, p.65, 2003.
RIZZINI, C. T. Tratado de Fitogeografia do Brasil. Aspectos Sociológicos e Florísticos, 2. HucitecEdusp, São Paulo, p.374, 1979.
SELBY, M. J. Hillslope: Materials and process. Oxford University Press, 1ª edição, Oxford, p.451,
1990.
SILVA, T.M. A estruturação geomorfológica do Planalto Atlântico no Estado do Rio de Janeiro. Rio
de Janeiro, UFRJ,264 p. 2002.
VIANA, V. M. Biologia e manejo de fragmentos florestais. In: Anais - Congresso Florestal Brasileiro,
6, Campos do Jordão, 1990. Curitiba: Sociedade Brasileira de Silvicultura/Sociedade de Engenheiros
Florestais, p.113-118, 1990.
Acknowledgments: To CNPq for funding this research and Stella Peres Mendes from Lagesolos
(UFRJ) for help with maps.