Matter turnover in the oligotrophic restinga ecosystem and the importance of the key species Clusia hilariana

Restingas are sandy areas spread along the Brazilian coast made up of a mosaic of forest and open woodland vegetation adapted to varying conditions of aridity, oligotrophy and salinity. Two vegetation types are very common in southeast Brazilian restingas, open Clusia formations and seasonally dry forest formation. Litter production and nutrient (C and N) turnover were studied comparatively in forest formations and Clusia formations, in vegetation patches with and without Clusia hilariana. The results showed that the breakdown process is extremely retarded in Clusia formations, with or without C. hilariana, leading to C accumulation in the soil. Microbial and soil fauna activity is lower in Clusia formations in comparison to forest formations; patches without Clusia hilariana showed intermediate conditions regarding total matter and carbon loss. Nitrogen loss was lowest in patches without C. hilariana, where soil micro-organisms accumulate N during the decomposition process, such as in the forest. The ratio of lignin in litter and the slow release of N reinforce the importance of the dominant tree Clusia hilariana as a potential key species for organic matter turnover. The accumulation of organic matter under the Clusia formation vegetation may be determinant for the humus richness of some bodies of water in the restinga, demonstrating the importance of this species to the ecosystem.

BIOPROSPECÇÃO DA FLORA FÚNGICA ENDOFÍTICA DA RESERVA DE JURUBATIBA

A preservação do bioma Restinga é de grande importância, pois ao mesmo tempo que este se apresenta como um dos mais ameaçados de extinção, pouco se sabe sobre a diversidade de fungos endofíticos que ali habitam, uma vez que estes fungos podem ser potenciais produtores de substâncias para a indústria farmacêutica, de cosméticos e de alimentos. Para os nossos estudos foram coletadas 34 espécies vegetais no Parque Nacional da Restinga de Jurubatiba, sendo 27 identificadas até o momento: Blutaparon portulacoides, Commelina erecta, Ipomoea pes-caprae, Schinus terebinthifolius, Allagoptera arenaria, Smilax rufescens, Byrsonima sericea, Sideroxylon obtusifolium, Guapira opposita, Clusia hilariana, Eugenia astringens, Remirea marítima, Inga maritima, Eugenia uniflora, Erythroxylum ovalifolium, Myrsine parvifolia, Manilkara subsericea, Cupania emarginata, Tocoyena bullata, Ipomoea imperati, Centrosema virginianum, Capparis flexuosa, Jacquinia brasiliensis, Inga laurina, Myrsine guianensis, Protium heptaphyllum e Canavalia rosea. Destas plantas foram obtidos 400 fungos endofíticos pertencentes a diferentes gêneros: Exserohilum; Gliocladium; Pestalotiopsis; Cladosporium; Curvularia; Penicillium; Phoma; Trichoderma; Aspergillus; Bipolaris; Guignardia; Beauveria; Alternaria; Colletotrichum; Nigrospora; Fusarium e Phomopsis, dentre outros. Cada isolado fúngico encontra-se devidamente armazenado e depositado na micoteca do LAQUIBIO, a fim de se garantir a preservação destas espécies e o fornecimento de culturas viáveis desses fungos para utilização futura.

Early detection of injuries in leaves of Clusia hilariana Schltdl. (Clusiaceae) caused by particulate deposition of iron

This study aims to evaluate the prognostic value of microscopic parameters of asymptomatic leaves of Clusia hilariana Schltdl. subjected to particulate deposition of iron (2.14 mg cm-2 day-1) for 45 consecutive days. Samples of young and expanded leaves without symptoms were collected and subjected to light and scanning electron microscopy techniques. The height of the epidermal cells on both surfaces of the leaf and the thickness of the hypodermis, the chlorophyll parenchyma, and the leaf blade were measured. Micromorphological injury occurred in the abaxial surface of young leaves and on both surfaces of expanded leaves. Erosion of the epicuticular wax and cuticle rupture were frequent on the adaxial surface, while on the abaxial surface of both leaves there was a loss of sinuosity on the anticlinal wall of the epidermal cells, stomatal deformity and obstruction. Micromorphometric alterations were seen in all leaf tissues except in the height of epidermic cells, probably due to the thick cuticle and prominent cuticular flanges. The highest difference in thickness of the leaf blade was seen in young leaves of plants subjected to SPMFe, indicating greater sensibility to particulate iron in comparison to the expanded leaves. The micromorphological and micromorphometric alterations in the leaf blade of Clusia hilariana Schltdl. showed the prognostic potential of these tools on the evaluation of impacts caused by the deposition of particulate matter, especially in the 'Restinga' natural vegetation, where the exposure is increasing due to the presence of iron ore industry in their surroundings.