Banco de sementes de uma área de caatinga submetida à adubação fosfatada.

Abstract

Many metabolic processes of plants require phosphor (P), which is one of the most limiting nutrient for forage production. Studies on seedbank of native pasture fertilized with P in semiarid regions are scarce. This study evaluated the seedbank floristic composition of litterfall + soil of a P-fertilized native pasture site located at the Fazenda Lameirão, an Experimental Station of the Universidade Federal de Campina Grande/Centro de Saúde e Tecnologia Rural (UFCG/CSTR), in the Sertão of Paraíba, Brazil. Collecion of the 80 samples of litterfall + soil occurred in November 2015 from five plots fertilized with 0, 30, 60, 90 and 120 mg dm3 of P2O5. The collected material remained in 80 plastic trays in an environment protected by a 50% solar radiation reduction plastic screen at the CSTR Forest Nursery facilities, under a daily watering regime during 296 days. Species identification followed the APG III (2009) classification system and the floristic composition variables derived from the Shannon-Wiener Diversity (H’) and Pielou Uniformity (e’) indexes. Data were analyzed by the ANOVA technic and treatment means were compared by the Tukey test (P<0.05). Emerged seedlings totaled 4987 plants and represented 24 families and 63 species. There were no significant effects of P2O5 on seedbank floristic composition, diversity and richness. Variations on floristic indexes probably resulted from the reduction of the grazing pressure practiced in the previous years. The emergence of seedlings of pioneer native caatinga tree species in the collected seedbank samples indicates that the successional process of plant community is in progress and can continue by the adequate management of the area.