Polinização por beija-flores em remanescente da Mata Atlantica pernambucana, nordeste do Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

Hummingbirds are the major vertebrate pollinators of Neotropical plants, pollination by hummingbird being found in many botanical families. Studies on pollination guilds constitutes an efficient way to understand ecological processes in natural ecosystems. During the period of May/1997 and January/1999 and August to Dezember/1999 we studied the ornithophilous guild of an Atlantic forest remnant in Pernambuco state, northeastern Brazil. Twenty seven ornithophilous plants were registered, but we included also two species that despite not being ornithophilous were efficiently pollinated by hummingbirds. Among these 29 species, 15 are Dicotyledons (11 famílies) and 14 are Monocotyledons (6 famílies), totalling 17 famílies and 25 genera. Bromeliaceae was the richest family with 27,6% of the guild species. Most of the species (64,3%) are epiphytes, facultative epiphytes or vines, followed by herbs (17,9%), shrubs (14,3%) and trees (3,5%). The majority showed red, red-orange or pink flowers (55,2%), with tube corollas (79,3%), measuring 31,4 mm length on average. Sugar concentration in the nectar ranged from 10,2 to 46,8% and the mean nectar volume varied from 2,5 to 97,4%. Although during the whole year one can find ornithophilous species flowering, most of them (91,7%) blooms during the rainy season. Eight species of hummingbird were registered in the community. Three of them were found to be residents, the remain were temporary. Due to the visiting behaviour, Glaucis hirsuta (Phaethornithinae) was considered as the dominant species. Comparisons with other studies on the same subject in southeastern Brazil Atlantic forest revealed similar richness of ornithophilous species. During the guild study two other studies were developed: one with the Bromeliaceae and a case history with Lundia cordata (Bignoniaceae). The first was based on the pollination and reproductive phenology of 8 ornithophilous species of Bromeliaceae (Aechmea fulgens, A. muricata, A. tomentosa, Billbergia morelii, Bromelia plumieri, Portea leptantha Tillandsia gardneri e T. stricta). The species flowered sequentially. The mean corolla tube length was 31,5 mm. Sugar concentration in the nectar was, on average, 29,9%, and the mean nectar volume was 29,4 ?l. Positive correlations between corolla length and nectar volume and concentration were detected. Five hummingbird species acted as pollinators of the Bromeliaceae (Amazilia fimbriata, Eupetomena macroura, Glaucis hirsuta, Phaethornis pretrei e P. rubei). Glaucis hirsuta visited the species with the longest tubes and highest nectar concentration. Phaethornis ruber visited ali species, acting as nectar thieves in Billbergia morelli, while P. pretrei was seen just twice, visiting flowers of only one species, Bromelia plumieri. Amazilia fimbriata and Eupetomena macroura visited, respectively, three and one species, always overlapping in the use of nectar with other hummingbird species. Bromeliaceae was considered one of the main sources of nectar to the hummingbirds of the community. The third study reports for the first time corolla-borne nectaries in a species of the neotropical genus Lundia A. DC. (Bignoniaceae). The floral biology, pollination ecology and flowering phenology of Lundia corda ta were investigated. This species is a typically ornithophilous liana, with reddish, tubular, and scentless flowers. The flowers are resupinate, protandrous and last for two days. There is a vestigial non functional perigynous disk and the nectar is secreted by glandular trichomes distributed along the internal surface of the corolla. The nectar is stored at the base of the corolla tube, thus showing secondary nectar presentation. The nectariferous trichomes are multi cellular, uniseriate, with a basal cell (foot) rooting in the epidermis, one neck cell, and a glandular head with 13 cells on average (9-17). Three species of hummingbirds (Amazilia fimbriata, Eupetomena macroura and Phaethornis pretrel) served as pollinators. Phaethornis ruber, Xy/ocopa bees, wasps and diurnal moths were considered nectar thieves

ASSUNTO(S)

mata atlantica polinização beija-flor

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