Maria das Dores Magalhães Veloso

Aspectos ecológicos da aroeira (Myracrodruon urundeuva Allemão- Anacardiaceae): fenologia e germinação de sementes

Myracrodruon urundeuva Allemao, especie arborea conhecida como aroeira, constitui-se em um importante componente das Florestas Estacionais Deciduais do norte de Minas Gerais. Apesar disso, a aroeira vem sofrendo um processo de exploracao intensa, de forma predatoria, o que vem causando a devastacao de suas populacoes naturais. Este trabalho teve como objetivo conhecer os padroes fenologicos reprodutivos e vegetativos, bem como a capacidade germinativa da aroeira, na Area de Preservacao da COPASA em Juramento, MG. Foram feitas observacoes fenologicas quinzenais, no periodo de janeiro/2002 a novembro/2003, de 20 individuos arboreos, sendo ainda coletadas sementes, submetidas a diferentes tratamentos de escarificacao tegumentar (mecânico, termico, quimico e controle). A especie apresentou as fenofases reprodutivas e vegetativas influenciadas diferencialmente pelas variaveis ambientais de precipitacao e temperatura. Na estacao seca ocorreram a floracao, frutificacao e queda foliar, e a estacao chuvosa favoreceu o brotamento da especie. A capacidade germinativa dos diasporos de aroeira variou entre os tratamentos utilizados, com potencial germinativo e velocidade de germinacao altos no tratamento-controle, indicando ausencia de dormencia. Nesse sentido, estudos basicos sobre as especies florestais ameacadas podem ser precursores de modelos e mecanismos para manejo e recuperacao de suas populacoes naturais.

STRUCTURE OF NATURAL REGENERATION IN RELATION TO SOIL PROPERTIES AND DISTURBANCE IN TWO SWAMP FORESTS

Veredas (palm swamps) is a type of vegetation associated with watercourses, characterized by the presence of Mauritia flexuosa palm trees. These systems are not well understood and suffer from high anthropogenic pressure. The aims of this study were to describe the natural regeneration of two swamp forests in vereda systems with different anthropogenic impacts and investigate if the variation in these plant communities are associated to edaphic conditions. The study was performed in preserved and impacted sites located in the Environmental Protection Area of the Pandeiros River in northern Minas Gerais. At each site, one hundred 25 m2 plots were established for surveying regenerating shrubs and trees (≥1 cm diameter at the base of the stem and < 3 cm diameter at breast height). Vegetation structure was evaluated by phytosociological parameters, similarity index, and size distribution of individuals. Regenerating strata was correlated with chemical and physical soil analyses. The vegetation at the preserved site was characterized by a higher number of individuals and a lower diversity but contained species that were typical of flooded areas. The results also showed differences in soil nutrient availability between sites that influenced the distribution of species at the two study sites.

SOBREVIVÊNCIA E CRESCIMENTO DE SETE ESPÉCIES ARBÓREAS NATIVAS EM UMA ÁREA DEGRADADA DE FLORESTA ESTACIONAL DECIDUAL, NORTE DE MINAS GERAIS

This study aimed to evaluate the growth and survival of seven native tree species in different treatments in a degraded area at COPASA Reserve (Juramento, MG). Approximately 1.2 ha area was used, where 899 seedlings were planted of seven native species (Anadenanthera colubrina, Copaifera langsdorffii, Dilodendron bipinatum, Miracrodruon urundeuva, Pterogyne nitens, Schinopsis brasiliensis and Senegalia polyphylla) followed for 24 months. The area was divided into five plots of 0.24 ha, which represented the following treatments: (T1) plot sown with grass (Brachiaria sp.); (T2) plot where the pits were treated with soil conditioner; (T3) plot sown with grass and legumes (Cajanus cajan) together; (T4) plot sown with legumes; and (T5) control. The mortality percentage was higher in T2 and lower in T3, and the species C. langsdorffii (43.66%) and S. brasiliensis (11.64%) were the ones with higher and lower mortality rate, respectively. The growth (height and diameter) of seedlings was higher in T2 (24.32 ± 26.05 cm and 0.51 ± 0.37 mm; respectively) and lowest in T1 (10,82 ± 22,57 cm and 0,26 ± 0,27 mm; respectively). The species with the largest growth in height were A. colubrina and S. polyphylla, and D. bipinatum and S. brasiliensis showed the highest growth in diameter. Pterogyne nitens showed the lowest growth, and highest mortality, presenting low ability to establish in degraded environments.

EFFECTS OF PRE-GERMINATION TREATMENTS AND STORAGE ON GERMINATION OF Astronium fraxinifolium SCHOTT (ANACARDIACEAE) DIASPORES

Este trabalho teve como objetivo avaliar a germinacao e a capacidade de armazenamento de diasporos de Astronium fraxinifolium. Para o experimento de germinacao, utilizaram-se seis tratamentos pre-germinativos: tratamento controle (diasporos intactos); diasporos imersos em agua a temperatura ambiente (25o C) por 5 min.; diasporos imersos em agua a 70° C por 5 min.; diasporos imersos em agua a 100° C por 5 min.; diasporos imersos em solucao de hipoclorito de sodio (1:1000) por 2 min.; e diasporos escarificados mecanicamente, com lixa no 80. Para determinar a capacidade de armazenamento, foram testados dois diferentes tipos de embalagem (saco de papel permeavel e vidro transparente) e duas condicoes ambientais (câmara fria e condicoes de laboratorio). Foram realizados testes de germinacao antes do armazenamento (tempo zero) e apos 60, 120, 180, 240, 300 e 360 dias de armazenamento. Os efeitos dos diferentes tratamentos pre-germinativos e das condicoes de armazenamento na germinacao dos diasporos foram avaliados por meio da ANOVA, seguida do teste de Tukey. Em relacao aos tratamentos pre-germinativos, foram observadas altas taxas de germinacao nos tratamentos com imersao em hipoclorito (98,0 ± 4,22%), controle (97,0 ± 4,83%), imersao em agua destilada a temperatura ambiente (96,0 ± 6,99%) e imersao em agua aquecida a 70oC (83,0 ± 29,08%). Dessa forma, os diasporos de Astronium fraxinifolium nao apresentaram dormencia. No armazenamento, os diasporos permaneceram viaveis durante todo o periodo de estudo, apresentando altas porcentagens de germinacao, com excecao do tratamento em saco de papel acondicionado em câmara fria, que perdeu a viabilidade no oitavo mes de armazenamento, nao sendo, portanto, um metodo de armazenamento recomendado para esta especie.

Survival of Saplings in Recovery of Riparian Vegetation of Pandeiros River (MG)

This study monitored the survival of saplings planted according to different recovery models in a riparian forest of the Pandeiros river (Januária, MG). The models consisted of planting the saplings in lines of 2 or 4 m with presence (T2S and T4S, respectively) or absence of direct seeding (T2 and T4, respectively). We planted 16,259 saplings of 17 botanical families, 32 genera and 33 species. The saplings, in general, presented a survival rate after one year of 34.4% (±1.8). The species with highest survival rates were Jacaranda brasiliana, with 85.0% (±13.5) of survival, Anadenanthera colubrina, with 70.1% (±7.0), and Triplaris gardneriana, with 69.3% (±9.1). Survival did not vary between the models tested, probably due to the short evaluation period (12 months).