Fenologia e chuva de sementes em um fragmento urbano da Floresta Atlântica em Pernambuco

Abstract

Considering forest fragments inserted in an urban matrix, differences are expected to be found between edge and interior of an urban forest fragment in terms of phenological patterns and seed rain. The study was performed in a forest fragment of The Caetés Ecological Station with 177 ha, Paulista, Pernambuco, Brazil. 551 arboreal individuals were marked (DBH>5cm), belonging to 123 species/morfospecies, in 40 10m² random parcels, distributed in the fragment’s edge (20 parcels) and interior (20 parcels). Phenological observations were performed from July/2008 to May/2010. In order to verify the community phenological patterns, the Fournier methodology was used. Circular statistics was used to analyze seasonality among phenophases. Results showed that species in the edge have exhibited a leaf fall peak in July/2008 (69%), sprouting peak in February/2010 (74%), flowering peak in April/2009 and February/2006 (13%) and fruiting peak in January/2009 (16.5%). Circular statistics analysis showed that all edge phenophases were significant, with a high seasonality in this habitat. In the interior only the sprouting and leaf fall peaks were significant. Seed rain was analyzed in three habitats, edge, interior and degraded area. 60 collectors were installed to analyze seed rain (0.25cm² each collector) and they were randomly set in the edge (20), interior (20) and degraded area (20). Collections were performed in the same time interval of the phenology. All material retained in the collectors was taken to the laboratory for further processing. Seed density per habita was calculated (seeds/m²); seeds were classified in five size classes; dispersion syndrome was considered as anemochoric, zoochoric and autochoric. From July/2008 to June/2010 6371 seeds were collected, belonging to 59 species/morfospecies. In the edge 3342 seeds were sampled, belonging to 48 species/morfospecies so that 45% of seeds were considered middle-sized and 45% were zoochoric. In the interior 2271 seeds were collected, belonging to 34 species/morfospecies. Medium-sized seeds were more frequent (44.1%) and zoochory highlighted with 55.88%. In the degraded area 758 seeds were collected, belonging to 19 species/morfospecies. Small seeds represented 42% in this habitat and zoochory highlighted with 42%. There was no significant difference between dispersion syndrome and the three studied habitats (p = 0.63). The same occurred with seed sizes and habitats (p=0.43).