Rafael de Paiva Farias

Selective fern herbivory by leaf-cutter ants of Atta cephalotes (L.) in Brazil

Although leaf-cutter ants of the genus Atta are polyphagous, they discriminate between food plant species. Ferns represent the second largest group of vascular plants and are especially abundant in tropical forest understories, but seem to be avoided as food plants. We studied the leaf damage caused by leaf-cutter ants and its relation with water content, trichome density, alkaloids, triterpenoids, and total phenol and nitrogen content of nine fern species occurring in close vicinity to Atta cephalotes (L.) nests from rainforests in Brazil. Meniscium serratum Cav. presented the highest leaf damage with 32.3%, three other species had a leaf damage of less than 5%, and the remaining five species were undamaged. Food preferences of leaf-cutter ants were related with higher water content (> 70%), but independent of any other measured variables. Additional observations from Mexico and Costa Rica provided evidence that a larger number of ferns are attacked by leaf-cutter ants. We suggest that highly damaged fern species might serve them as an occasional, short-term, alternative diet when growing close to ant nests, whereas less damaged fern species might have some chemical components harmful for the fungus and detected a posteriori, because they were rejected after initial harvesting by leaf-cutter ants.

First record of galls in the tree fern Cyathea phalerata (Cyatheaceae) from a Tropical Rainforest in Brazil

aPrograma de Pós-graduação em Biologia Vegetal, Universidade Federal de Pernambuco –UFPE, Rua Prof. Nelson Chaves, s/n, Cidade Universitária, CEP 50670-420, Recife, PE, Brazil bCentro Acadêmico de Vitória, Universidade Federal de Pernambuco – UFPE, Rua Alto do Reservatório, s/n, Bela Vista, CEP 55608-680, Vitória de Santo Antão, PE, Brazil cDepartamento de Entomologia, Museu Nacional, Universidade Federal do Rio de Janeiro – UFRJ, Rua Quinta da Boa Vista, s/n, São Cristóvão, CEP 20940-040, Rio de Janeiro, RJ, Brazil dInstituto de Ecología – INECOL, A.C., Red de Ecología Funcional, Carretera antigua Coatepec, 91070, Xalapa, Veracruz, México

Abiotic factors drives floristic variations of fern’s metacommunity in an Atlantic Forest remnant

We analyzed floristic variations in ferns metacommunity at the local scale and their relationship with abiotic factors in an Atlantic Forest remnant of northeastern Brazil. Floristic and environmental variations were accessed on ten plots of 10 × 20 m. We performed cluster analyses, based on Bray-Curtis dissimilarity index to establish the floristic relationship. The influence of abiotic factors: luminosity, temperature, relative air humidity and relative soil moisture was evaluated from a redundancy analysis. We found 24 species belonging to 20 genera and 12 families. The ferns flora showed high floristic heterogeneity (>75% for most of the plots associations). The ferns metacommunity was structured along an abiotic gradient modulated by temperature, luminosity, and relative soil moisture.

Leaf Phenology of Danaea geniculata (Marattiaceae) in a Submontane Tropical Forest, Brazil

Abstract.— Ferns adapt their phenological characteristics such as leaf production, leaf fertility and leaf mortality to the habitat conditions optimizing their opportunities to grow, reproduce, and disperse. The leaf phenology of the herbaceous, dimorphic fern Danaea geniculata was studied in a Brazilian submontane tropical forest and compared with several other fern species worldwide. Plants of D. geniculata held an average of 8.11 ± 2.16 leaves that were produced and died at similar rates of 4.44 ± 2.16 leaves y−1 and 4.20 ± 2.28 leaves y−1, respectively. Leaf lifespan was 24.7 ± 7.5 mo for sterile leaves and 5.6 ± 0.6 mo for fertile leaves. Leaf production and fertility increased with rainfall, but decreased with temperature, because of the local climate, which is characterized by higher rainfall during the colder winter months. On the other hand, leaf mortality increased during drier and hotter months. Leaf production and fertility of other species were fit into three categories and compared with D. geniculata. The leaf phenology of D. geniculata neither coincided with species at the same site nor with species within the same family (Marattiaceae), indicating that even coexisting or closely related species can adapt individually to the macro- and microclimatic parameters of their habitats.