Open Journal of Forestry
Vol.04 No.02(2014), Article ID:43172,9 pages
10.4236/ojf.2014.42021

Natural Regeneration in Tropical Secondary Forest in Southern Amazonia, Brazil

Alexandre Ebert, Leandro Ribeiro Teixeira, Adriana Zanirato Contini da Silva, Reginaldo Brito da Costa

Faculty of Forestry Engineering, Federal University of Mato Grosso, Cuiabá, Brazil

Email: ebertfloresta@yahoo.com.br

Copyright © 2014 Alexandre Ebert et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In accordance of the Creative Commons Attribution License all Copyrights © 2014 are reserved for SCIRP and the owner of the intellectual property Alexandre Ebert et al. All Copyright © 2014 are guarded by law and by SCIRP as a guardian.

The study aimed to establish floral composition, diversity levels, category size, phytosociological struc- ture, commercial use and ecological group of species present in the regeneration of open ombrophile forest in southern Amazon, Brazil. Data were collected at São Nicolau farm, in the municipality of Cotriguaçu, northwest of Mato Grosso state, coordinates 51˚9'19.5"S and 58˚14'53"W. One hundred plots of 10 × 10 m were allocated. All individuals between 29.9 and 59.9 cm had circumference at breast height (CAP) measure, with sub-plots of 5 × 5 m which were measured in all subjects between 1:50 m in height 29.9 cm CAP and sub​​-plots of 2 × 2 m for individuals between 0.30 to 1.5 m tall. The information obtained in the field were processed in excel spreadsheet. The results showed the occurrence of 610 individuals belonging to 82 species, 34 plant families, with a diversity index of Shannon & Weaver’s 2.77. The index of value of importance showed species Protium robustum, Maquira calophilla and Inga fagifolium with greater ecological importance in fitocenose. The higher values ​​for Natural Regeneration were the species Protium robustum, Maquira calophilla and Inga fagifolium with 16.42, 8.03 and 7.76 respectively.

Keywords: Vertical Structure; Ecological Analysis; Forest Management

Introduction

The fabulous Amazon’s biodiversity has been the subject of numerous debates in different social spheres. With the increas- ing demand for forest resources and prospects of population growth, these demands are expected to increase, particularly for tropical timber. With this in mind society has been put on alert. What is the carrying capacity of natural environments to resist human interventions and conserve the ecological and genetic interrelationships among species? The answer to this question needs to meet the needs of the present without compromising the needs of future generations as it was referred by Burtland in the report (Our Common Future) in 1987.

Sustainable forest management aims at using forest resources while keeping forest biodiversity and resilience. Studies of forest and natural regeneration enable a better understanding of the effect of the extraction of wood in tropical forests (Park et al., 2005; Zimmerman & Kormos, 2012), and as Araújo (2011) points out, it is important to know more about tree species be- havior and natural regeneration to define the appropriate silvi- cultural management for forest species.

Forest management based on natural regeneration is accom- plished by concentrating efforts on conserving biodiversity, therefore ensuring the vital functions of forests, as well as the continuity in the supply of various social and economic benefits (Nasi & Frost, 2009). It is determined by studies and surveys which help activities, inventory planning and exploitation of timber.

Natural regeneration is the renewing of trees in a forest and provides natural replacement of individuals. It becomes essen- tial to take this into account when exposing large areas of forest logging. Many forest species are endangered mainly as a result of pressure by the intensive exploitation due to their high eco- nomic value (Fontana et al., 2003; IBAMA, 2008; Hubel et al., 2008). Thus, it becomes necessary to carry out surveys and studies on specific ways to lead to replacement of forest stock, with the maintenance of the natural reproductive processes of regeneration.

Studies of aspects related directly or indirectly to natural re- generation include auto ecology, success stage and the effects of forest exploitation (Higushi et al., 1985). They are crucial when compared with studies conducted for mature individuals, or considered as inventory growth and future exploration, (Scolforo, 1998). The importance becomes more evident when one considers that the quantitative and qualitative characteris- tics of mature forest are intimately related to the dynamic processes of biotic and abiotic natural regeneration, which con- sequently will continue the maintenance of forest biodiversity.

Several factors can influence natural regeneration. Calegario (1998), for instance, suggests successional stages as determi- nant interacting climatic factors, as well as biotic, edaphic, phy- siographic and anthropogenic.

In areas of the Amazon rainforest, the study of natural rege- neration involves complex knowledge, due to the great diversi- ty of species and functional processes related to ecological in- teractions, to microclimatic extracts provided by the forest and the diversity of geomorphologic environments. This study aim- ed to determine the floristic composition, diversity levels, size category, phytosociological, use group and the ecological group of species in the regeneration of rain forest the Southern Ama- zon, Brazil.

Materials and Methods

The study was conducted at São Nicolau farm, located in the municipality of Cotriguaçu, northwest of Mato Grosso state, Brazil (Figure 1). The farm belongs to the Brazilian branch of the Office National des Forêts (ONF Brazil), and has an area of ​​100,000 km2, of which 70,000 km2 are covered with secondary open rain forest, reforestation of 20,000 km2 with tree species intercropped with pasture and 10,000 km2 ha with riparian areas fragmented.

The farm lays in a region where weather prevails belonging to group A tropical rainy climate, (Brazil, 1982), with type climate “Am”, common to the short period of drought and rainfall below 60 mm in the driest period year (June to Sep- tember).

For data collection permanent plots were allocated by the method of sampling for fixed area plots distributed systemati- cally in two stages (Pellico et al., 1997).

The original vegetation types of the study area comprises the typology Open Tropical Rain Forest (Brazil, 1982), submon- tane formation with palm trees. Its physiognomy shows large trees spaced grouped with palm trees presenting a number of

features with large leaves and rough bark.

Altogether, there were 50 plots subdivided into two sub-plots totaling 100 sampling units measuring 100 m2 (10 × 10 m), in which were accounted all individuals measuring between 30 and 59 cm in circumference at breast height (HBC), 100 plots of 25 m2 (5 × 5 m), for all young individual trees, measuring between 1.5 m in height and 30 cm in circumference and sub​​- plots of 4 m2 (2 × 2 m) for regeneration of plants up to 1.5 m tall (Figure 2).

The identification and cataloging of species in the field were carried out by two practical identifiers and botanist Program Management of Tropical Forests PROMANEJO/FENF/UFMT. The identification and measurement of species, data were rec- orded on field sheets, containing botanical identification by common name, circumference at 1.3 m height above the ground, the circumference height and commercial height.

The data collected were processed in an MS-Excel® spread- sheet obtaining results through natural regeneration phytosoci- ological structure parameters such as density, frequency and index of value of importance. To calculate the diversity of nat- ural regeneration was used the diversity index of Shannon- Weaver.

In size classification of natural regeneration, it was used the classification suggested by FAO (1971): Class CT1 or seedling: 0.3 m < h < 1.5 m; seedlings or CT2: 1.5 m < h < 3.0 m; CT3 or change established: h > 3.0 m DBH < 5.0 cm; CT4 or rod 1: 5.0 cm > DBH < 10 cm; CT5 or dipstick 2: 10 cm < DBH < 20 cm.

To determine the estimated natural regeneration it was used the methodology proposed by (Volpato, 1994), which uses the values ​​of frequency and absolute abundance of each species in each size class.

Figure 1.

Location map of the study area.

Received November 30th, 2013; revised January 3rd, 2014; accepted January 23rd, 2014

Figure 2.

Distribution of permanent plots, each was subdivided.

The abundance and relative frequency were calculated for each species in each class size, assuming that the denominator is constructed by summing the abundances and absolute fre- quencies of all species in all size classes. Further, it was esti- mated the natural regeneration by size class plant, adding par- tial values ​​of relative frequency and relative abundance of nat- ural regeneration by size class of plant studied, combining them into a unique expression as follows:

where RNCij = estimate of the natural regeneration of the ith species in the jth class of plant size in percentage.

Determined an estimated total natural regeneration by spe- cies using the equation:

where RNTi = estimate of the Natural Regeneration total ith species.

The sum of the RNT of all species, as calculated above, equals 100. Thus, each individual value, either by size class or kind, is being expressed in percentage.

Results

Floristic Composition

The survey for the inventory of natural regeneration of tree species identified a total of 610 individuals belonging to 82 species that are distributed in 34 botanical families. The fami- lies with the highest floristic diversity were: Fabaceae, with 17 genera and 18 species, Moraceae with 5 genera and 5 species, Melastomataceae with 3 genera and 4 species Burceraceae with 2 genera and 4 species, as shown in Table 1.

For diversity analysis, by calculating the diversity index of Shannon & Weaver (H') value obtained was H' = 2.77.

Analysis of the Distribution of Natural Regeneration in Succession Groups

Categorization of natural regeneration of species between ecological groups grouped into size classes resulted in the data listed in Table 2.

It is observed in the prevalence pioneer species, totaling 271 individuals in 33 species, following the climax species with 204 individuals in 19 species and 132 individuals with secondary in 28 species (Figure 3).

These results suggest that the forest in study underwent re- cent exploratory interventions and based on resilience the same, succession processes is still being established, forming an ini- tial structure of natural regeneration. This process is commonly viewed in areas that suffered extensive logging.

In group use of the species studied (Table 3) considered the supply and demand for timber products and non-timber species in the region, detecting a satisfactory number of commercial species, total: 38 species, 31 timber species 5 and the second food producing latex and oil. In the clustering of non-commer- cial trees were identified 44 species, of which at least 5 are used by local communities for the production of medicines, crafts and tool handles. It is noteworthy in this context, the species Siparuna guianensis Aublet used to relieve headaches, and Co-

Table 1.List of species raised in the study area, in alphabetical order by family, common and scientific name and its associated ecological group, and ecological group.

Ecological grouping (EG) = PI, pioneer, SE, secondary, CL, climax, PA, Palmae.

Table 2.

Table 3.

Figure 3.

Graphical representation of species by size class in succession stages.

paifera sp which is extracted oil much used in healing wounds and sore throats.

Values ​​of Total Natural Regeneration of tree species with the highest importance, in descending order were; Protium robus- tum 16.42%, Maquira callophylla to 8.03% and Inga fagifo- lium with 7.76% , respectively (Table 4). Can observe the val- ues ​​of natural regeneration studied, with the respective values ​​of absolute abundance by size class of the studied plants. These values ​​allow us to analyze the regeneration by plant size.

Phytosociological Parameters

The total density of natural regeneration was 8.320 individu- als/ha, and the individuals who had the highest values ​​were: Protium robustum, Maquira callophylla, and Mouriri fagifo- lium and Inga sp respectively.

The amounts related to abundance, and absolute and relative frequency of each species Importance Value Index expanded, are shown in Table 5. These values ​​indicate the ecological importance of each species, i.e., its value in fitocenose studied.

The results related to the Amplified Importance Index Value which defines the ecological importance of the species within the community, allows making decisions about the manage- ment techniques based on guarantees replacement of existing individuals.

The species with the highest importance values ​​obtained AIVI refer to tree and shrub species, highlighting the Protium robus- tum, a timber kind suffering strong pressure exploration in the Amazon region; however it is noted that the species responds positively to the processes natural regeneration. Figure 4 graph- ically illustrates the species that showed best AIVI.

Discussion

The current structure of the natural regeneration of the forest studied reflects intense logging in previous years, a fact that establishes succession stages presented. Despite not being able to establish the most intense period of exploration, it was noted that decades after logging still occur marked differences in the floristic composition and structure of ecological succession, especially in places where there were sharp impact on explora- tion, such as creating large clearings, stockyards and skid trails. The results obtained show that the structure of the forest is renewed by natural regeneration in face of disturbances caused by selective harvesting of timber. It’s due probably by the high resilience of local environment.

The structure of natural regeneration in disturbed forests may suffer different arrangements according to the intensity. Hirai et al. (2012) and Garden et al. (2007) studying the effects of log- ging on natural regeneration in a forest, concluded that the flo- ristic composition is modified in areas directly affected during exploitation, suffering changes along the years, occurring natu- ral replacement of species serial stages. Species diversity was considered in a satisfactory level. Studies performed by Gamma et al. (2003), studying the natural regeneration in lowland fo- rests in the Amazon estuary, they obtained similar results with H' = 3.05, for comparison.

Almeida et al. (2012) evaluating phytosociology in managed forest in the municipality of Santarém, in Pará state, obtained H' = 4.39. Probably, the differences found in the results ob- tained in studies of diversity refer to different vegetation types, and/or the intensity of explorations carried out in previous years.

The distribution of the number of plants, as expected, de- creased with increasing class size, put in categories 2 and 3 (changes and changes made) there was considerable decrease of plants, which can be attributed to interspecific competition or related syndromes pollination and/or dispersing agents.

Results show high incidence of commercial species repre- senting the natural regeneration of trees possibly exploited in previous years. Gomes et al. (2011) concluded in their studies conducted in managed rainforest in Bolivia that natural regene- ration of tree species exploited continues after the intervention and does not compromise the structure of the natural regenera- tion of commercial species.

Conclusion

The results obtained in this study lead which species may fuel demand for raw material for timber and non-timber forest products, showing a useful strategy that allows the perpetuation of natural forests, supporting exploratory practices that consider ecological parameters maintenance of intra-and interspecific relationships.

Table 4.

Table 5.

AANR: Absolute Abundance of natural regeneration; ARNR: Abundance concerning natural regeneration; AFNR: Absolute frequency of natural regeneration; RFNR: Relative frequency of natural regeneration; AIVI: Index magnified importance.

Figure 4.

Graphic illustration of the species with the highest Amplified Importance Index Value.

Acknowledgements

ONF Brazil for all the logistical support for the work done in the field, and the Coordination of Improvement of Higher Level Personnel―CAPES for the scholarship granted.

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