-(Seed germination of Dyckia tuberosa (Vell.) Beer (Bromeliaceae) under different temperature in light and darkness). The effects of temperature and light on the germination of seeds of Dyckia tuberosa (Vell.) Beer, a terrestrial bromeliad from "cerrado", were studied. Seeds collected at Estação Ecológica of Itirapina, São Paulo State, were incubated at constant temperatures in the range of 10 to 45 °C, under continuous white light and darkness. The range of temperature with highest germinability under light was from 15 to 40 °C and from 20 to 40 °C in darkness, with no germination at 10 and 45 ºC for light and darkness. For both, light and darkness, the optimum temperature was in the range of 30 to 35 °C. The high germinability at high temperatures shows that D. tuberosa is able to germinate in open areas and the light insensitivity of the seeds indicates that they can also germinate in conditions of completely darkness. Apparently, the germination process is not a limiting factor for this species.

-(Seed rain and natural regeneration under three woody species in a forest in process of restoration). The present study describes the composition of the natural regeneration and seed rain under three early successional tree species -Centrolobium tomentosum Guill. ex Benth. (Fabaceae), Cordia myxa L. (Boraginaceae) and Melia azedarach L. (Meliaceae) in a 15 year-old mixed plantation. Fifteen individuals of each species were selected, and under each crown two seed traps (1 m 2 each; total of 90 seed traps) were set, they were sampled monthly for one year. The natural regeneration was evaluated in circular plots (17.6 m 2 ) established under the projection of the crowns, where all individuals of woody species between 0.3 m and 2.0 m in height were counted and identified. The seed rain had higher mean density under M. azedarach and higher richness under C. myxa. Species diversity of natural regeneration was higher under M. azedarach and individuals were taller under C. myxa. Most of the individuals and species sampled were from early successional species, mainly exotic species. It is discussed the development of microsites and their influence on the community structure and composition.Key words -canopy, forest restoration, natural regeneration, seed rain RESUMO -(Chuva de sementes e regeneração natural sob três espécies arbóreas em uma floresta em processo de restauração). O presente estudo teve como objetivos caracterizar a composição da regeneração natural e da chuva de sementes presentes sob a copa de três espécies de início de sucessão -Centrolobium tomentosum Guill. ex Benth. ) sob as copas das árvores, onde foram amostrados os indivíduos arbustivo-arbóreos de 0,3 a 2,0 m de altura. A chuva de sementes sob M. azedarach apresentou maior densidade média e sob C. myxa maior riqueza. Quanto à regeneração natural, as comunidades diferenciaram-se em relação à diversidade de espécies (maior sob M. azedarach) e à estrutura (indivíduos maiores sob C. myxa) entre as espécies do dossel. A maioria dos indivíduos e espécies amostradas pertence aos estádios iniciais da sucessão e muitas, dentre as mais abundantes, são exóticas. Discute-se a formação de nichos de regeneração sob elas e a influência dessas na estrutura e composição dessas comunidades.Palavras-chave -chuva de sementes, dossel florestal, regeneração natural, restauração florestal

The effects of the temperature and light on the control of seeds germination in

The aims of this study were to evaluate the effects of light and temperature on seed germination and the effect of light on seedling emergence of Clausena excavata, an invasive exotic species. Seeds were incubated at constant temperatures (10 to 40 ºC), under continuous white light and darkness. Seedling emergence was evaluated under full sun and canopy shade. There was no significant difference between seeds germinated in the presence or absence of light at temperatures between 20 and 35 ºC. Seeds maintained at 20 ºC germinated more slowly than other temperatures. Independent of temperature, seed germination was much more synchronised under white light than under darkness. In the field, emergence occurred in both environments, but a greater percentage was observed under full sun. Seedling emergence occurred at the same rate and synchronisation index under both conditions. C. excavata has a high invader potential in open areas and shaded environments.

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