Soraya Alvarenga Botelho

Estudo da vegetação como subsídios para propostas de recuperação das nascentes da bacia hidrográfica do ribeirão Santa Cruz, Lavras, MG

The objectives of this study were to survey the floristic composition of the arboreal and regenerative stratum of the headwaters of the Santa Cruz River watershed and to select species to be used for reforestation of degraded and disturbed headwaters of the watershed. The floristic and structural surveys were carried out in twelve headwaters. Detrended correspondence analysis (DCA) and cluster analysis were used to compare the floristic profile among the headwaters. The vegetation of the arboreal stratum presented higher diversity in the disturbed than in the degraded headwaters, as well as in the punctual than in the diffuse springs. The floristic similarity of the regenerative stratum among the headwaters of the same category allowed to infer that preferential species should be used for each state of conservation (disturbed or degraded) and environmental condition (humid or well drained soil) in reclamation programs of permanent preservation of headwaters in the Santa Cruz River basin.

Morfologia de frutos, sementes, plântulas e plantas jovens de Dimorphandra mollis Benth. - faveira (Leguminosae-Caesalpinioideae)

Foram estudados os aspectos morfologicos externos e internos do fruto e da semente, alem de aspectos externos do processo germinativo e das fases de plântula e planta jovem de Dimorphandra mollis Benth. O trabalho foi realizado em laboratorio e casa de vegetacao, sendo observado que os frutos sao indeiscentes, as sementes sao albuminosas, a germinacao e epigea fanerocotiledonar e, na fase de planta jovem, ocorre um espessamento das raizes primaria e secundarias. Os resultados apresentados podem ser uteis em estudos taxonomicos, em trabalhos de laboratorio e viveiro, bem como para estudos de regeneracao natural.

Avaliação do crescimento do estrato arbóreo de área degradada revegetada à margem do Rio Grande, na Usina Hidrelétrica de Camargos, MG

n The objective of this study was to analyze the growth of tree species planted in a topographic gradient in an area degraded for the construction of the dam of Camargos Hydroeletric plant, MG. At 155 months after planting, three transects following the slope, 15 m wide and variable length were allocated, subdivided in parcels of 12 x 15 m along the topographic gradient. Plants with diameter at breast height (DBH) ≥5 cm were identified and measured (DBH and height). We concluded that, generally, the pioneer species showed a faster growth rhythm in the first 58 months and the climax species in the period of 58 to 155 months. Plant growth was affected by soil compactation and the effect of the topography gradient.

Regeneração natural como indicador de recuperação de área degradada a jusante da usina hidrelétrica de Camargos, MG

The process of natural regeneration in an area degraded for the construction of the Camargos hydroelectric plant dam, MG, was analyzed 155 months after the planting for its reclamation. The analyses were done in function of the distance to the river, soil compaction and distance of the seed sources. The survey of the natural regeneration was done in plots of 2 x 15m allocated every 10m along three transects (15m width and variable length) parallel to the slope direction. All plants with DBH 10cm were identified and measured in height. Sixty four species of 27 families were found. The adjacent fragment provides a great amount of propagules for the natural regeneration, since many regenerative species in the recovering area were found only in the arboreal stratum of that fragment. A distance of up to 75m to the fragment did not affect the regeneration density, height and diversity, but in the plots taken by the grass Mellinis minutiflora, the density was smaller and the plants higher.

ESTABELECIMENTO DE MATA CILIAR ÀS MARGENS DO RESERVATÓRIO DA USINA HIDRELÉTRICA DE CAMARGOS, MG

The object of this survey was to analyze the growth and vigor of arboreal and shrub species planted in a reservoir shore of the Camargos Hydroeletric Plant, in the state of Minas Gerais, and to verify the processes of natural regeneration in function of the reservoir distance and along the planted area. At 150 months, in the arboreal species inventory, all the planted and the natural regenerations with diameter at breast height ³ 5 cm were measured. Grades (1.0 to 5.0) were attributed for the evaluation of the tree vigor. For the natural regeneration survey, four transects were demarcated and three 1 x 15 m plots were established in each transect, following the slope. Results showed that some of the pioneer species displayed senescence signs after 13 years of planting. In the natural regeneration, 55 species of 27 families were identified. Species of the Asteraceae family predominated in the more disturbed areas, because they are adapted to these conditions. There was predominance in zoochoric dispersion among the regenerating species. The greater regeneration density was found near the reservoir, whereas the bigger diversity and average height were found in the opposite side of the planted area.

Caracterização ecológica de espécies arbóreas ocorrentes em ambientes de mata ciliar, como subsídio à recomposição de áreas alteradas nas cabeceiras do Rio Grande, Minas Gerais, Brasil.

The objective of this study was to verify the differences in the composition of the flora and of guilds of arbustive-arboreal communities of three areas of ciliary forest, in different forest succession stages. Fourty-six plots of 400 m 2 were allocated and all existent arboreal individuals inside the portions with diameter breast height (DBH) greater than or equal to 5cm were sampled. A total of 282 species, distributed in 140 genera and 61 families were identified. With regard to dispersal guilds, it was found that on average, the spread of sources of propagules of 72% of the species and 59% of the individuals was zoochorous, while 19% and 23%, respectively, was wind anemocoric, and 6% and 13%, respectively, was autochoric. The proportions of individuals per species and ecological group were, respectively, pioneers: 14.5% and 18%; climax demanding of light: 49.5% and 62.5%, and shade-tolerant: 36.5% and 21.5%. It was also verified that there was a significant increase in the importance of animal dispersed species and shade tolerant species with the maturity of forests, while the number of species that required light abiotically dispersed decreased significantly with the advancement of maturity.

Potential of natural regeneration as a method of restoration of degraded land surrounding water springs

This work evaluated the potential of natural regeneration in the restoration a disturbed water spring surrouding, after stopping the impacts, on forest and wasted grazing land. It was analyzed the structure of the stratum and natural regeneration under canopy and in open area surrounding a water spring under process of recovery, located in Nazareno, Minas Gerais. The tree stratum was assessed in 4 permanent plots (10 × 50 m), sampling, identifying and measuring height of trees with DBH  5 cm diameter. For assessing the natural regeneration, 16 plots (10 × 2 m) were set. Trees with height> 10 cm and DBH <5 cm were identified and measured. The samples were established at 7 and 51 months after the isolation of the area. Phytosociological parameters of the tree and regenerative strata were calculated for each species, classifying them by the type of dispersal and ecological group. Shannon diversity index and evenness were calculated for each community which were also compared by Sorensen index. The results showed that the areas are dissimilar, with most species found at the regeneration under canopy, showing a intake in the system. The communities had a high proportion of zoochoric species and pattern of higher light demanding climax species and a decrease in the proportion of pioneer species from one inventory to another, indicating progress in natural succession. The density of the individuals regenerating under canopy was much greater, probably due to the dominance of Brachiaria in the open area, showing that use of the regeneration as a unique method of recovery should not be applied.

Regeneração natural em áreas desmatadas e dominadas por Pteridium aquilinum (L.) Kuhn. na Serra da Mantiqueira

Objetivou-se analisar a sucessao ecologica em areas desmatadas e dominadas espontaneamente por Pteridium aquilinum na Serra da Mantiqueira, por meio do levantamento da regeneracao natural de especies arbustivo-arboreas, bem como avaliar a influencia dos historicos de perturbacao e condicoes edaficas. Amostraram-se duas areas em Bocaina de Minas, Minas Gerais, em regeneracao ha 6 e 20 anos, com 60 parcelas de 10 m², inventariando-se os regenerantes de 0,15 a 3 m de altura, todos identificados e medidos em diâmetro e altura. Registraram-se 1.159 individuos de 53 especies, destacando-se a familia Melastomataceae pela maior riqueza e abundância. As areas diferenciaram-se na composicao de especies, com similaridade de Jaccard de 3,7%. Sob analise de correspondencia canonica, a area de seis anos evidenciou correlacoes positivas entre a comunidade regenerante e teores de fosforo nao labil e argila, enquanto a area de 20 anos mostrou correlacoes com K, P, Ca, Al, pH e soma de bases trocaveis, alem de maiores densidades de Pteridium. Os resultados demonstraram que a dominância de P. aquilinum conduz a uma sucessao ecologica sob inibicao, onde a samambaia atua negativamente sobre a riqueza e abundância de populacoes arbustivo-arboreas. Tambem se confirmou a preferencia da especie por terrenos declivosos, a maiores altitudes, com solos mais acidos, beneficiando-se tambem de disturbios. Por outro lado, chama-se a atencao para a suscetibilidade desses ambientes montanos e para a importância da preservacao de sua vegetacao natural, assim como do desbaste das samambaias como estrategia de restauracao florestal.

INFLUENCE OF ECOLOGICAL GROUP COMPOSITION, PLANTATION SPACING AND ARRANGEMENT IN THE RESTORATION OF RIPARIAN FOREST ON RESERVOIR SHORES

This work aimed to assess the effect of spacing, arrangement and ecological group composition of planted seedlings on the restoration process of artificial reservoir shores in southeastern Brazil. The assessments were performed 12 years after the settlement of the experiment in which five mixed stand models were tested. First, a general evaluation of the stand was performed when we surveyed the overstory and understory, seed bank and soil for chemical analysis. Then, the survival restoration indicators of planted trees, basal area and density of the tree community, litter accumulated on the soil and canopy closure index were utilized to compare the plantation models and to assess the influence the experimental factors on these parameters. In the general analysis, we found that the studied stand presents low diversity, poor regeneration, and seed bank dominated mostly by one planted exotic tree species and weeds, which may jeopardize the self-maintenance of the stand in the future. The factor that most influenced the models was the ecological group composition with the best performance found for models in which both pioneer and non-pioneer groups were used. Probably, the plantation arrangement and spacing do not have greater influence due to both plant mortality and natural regeneration that has developed to this age. Hence, it is not recommended the use of only pioneer species in the implantation of riparian forest and the proportion of 50% pioneers and 50% non-pioneers using as much species as possible is indicated for areas that might present constraints for the natural regeneration.

Avaliação da regeneração natural em nascentes perturbadas no município de Lavras, MG.

This work aimed at evaluating the natural regeneration dynamics in two springs in process of recovery in Lavras-MG, surrounded in December/2003. To do that, two springs were carried out from August/2005 (18 months) to April/2006 (24 months). 122 plots in the total of 5 x 5m (25m 2 ) were plotted, being 76 plots in spring 1 and 46 plots in spring 2. The plots were distributed systematically throughout all the area of the springs. All individuals with height larger than 0.10 m and DBH lower than 5 cm were identified, having their diameters and height measured. Floristic composition, structural analyses and natural regeneration dynamics were studied. In the total, 524 individuals from 24 family and 55 species were sampled. The Asteraceae family was distinguished in species number in spring 1 and the families Fabaceae Faboideae, Myrtaceae and Solanaceae in spring 2. The species Baccharis dracunculifolia and Vernonia ferruginea presented the highest natural regeneration indexes in spring 1, while the species Vernonia polyanthes and Nectandra nitidula in spring 2. The higher diversity index was registered for the spring 2 in the second evaluation, having an increase from 3,324 (first evaluation) to 3,384 (second evaluation). The floristic similarity index registered between the springs was of 20.0% and 18.5% for the evaluations 1 and 2, respectively. During the time of monitoring, it was verified a significant increase of 33.33% and 15.8% in individuals number sampled in springs 1 and 2, respectively. The natural regeneration method presents potential for the recovering of the vegetation of the two springs; however, it is necessary the adoption of control techniques of Brachiaria sp. grass.