RESUMO

Abstract Montane ecosystems in South America harbor high levels of endemism typically with species that are often threatened. Here we investigated fruit and seed morphology, germination, and early growth parameters of Crinodendron brasiliense, an endangered and narrow endemic tree species of subtropical montane cloud forests in Southern Brazil. We obtained fruit and seed size and shape, number of lobes and number of seeds per fruit and evaluated germination and early growth parameters in a greenhouse. We tested the effect of different container types and parent plant on seed morphology, germination, and early growth. We also tested whether thermal scarification would improve germination rates. We showed that parent plant significantly influenced fruit and seed morphology as well as early growth rates. The germination rate of the species was extremely low (0.003-0.004%), which may be one important underlying cause of its small population size and restricted distribution. Thermal scarification was ineffective to improve the germination of seeds. Unexpectedly, container type significantly affected germination success, as seeds in trays germinated faster and in higher rates than seeds planted in seedbeds. Such result suggests a higher soil moisture could improve germination success. Our study is the first documented propagation of the species and provides essential aspects on the reproductive biology and early development of Crinodendron brasiliense. We highlight the urgent need for further research and collaborative conservation initiatives to prevent the extinction of this species.

Resumo Investigamos la morfología de frutos y semillas, la germinación y los parámetros del crecimiento inicial de Crinodendron brasiliense, una especie arbórea en peligro de extinción y endémica de los bosques montanos del sur de Brasil. Obtuvimos el tamaño y la forma de frutos y semillas, el número de lóbulos por fruto y el número de semillas por fruto, además de evaluar los parámetros de germinación y crecimiento inicial - desconocidos para la especie. Demostramos que la planta madre influyó significativamente en la morfología de frutos y semillas, así como en las tasas de crecimiento inicial. La tasa de germinación de la especie fue extremadamente baja (0.003-0.004%), lo que podría ser una causa importante para explicar su pequeño tamaño poblacional y restringida distribución. La escarificación térmica fue ineficaz para la germinación de semillas. Inesperadamente, el tipo de contenedor afectó significativamente el éxito de la germinación, ya que las semillas plantadas en bandejas germinaron más rápido y en tasas más altas que las semillas plantadas en semilleros. Tal resultado sugiere que una mayor humedad del suelo podría mejorar el éxito de la germinación. Nuestro estudio es el primer registro documentado de la propagación de esta especie y proporciona aspectos esenciales sobre la biología reproductiva y el desarrollo inicial de Crinodendron brasiliense. Destacamos la necesidad urgente de realizar más estudios e iniciativas de conservación colaborativas para evitar la extinción de esta especie.

RESUMO

Positive interactions in plant communities are under-reported in subtropical systems most likely because they are not identified as stressful environments. However, environmental factors or disturbance can limit plant growth in any system and lead to stressful conditions. For instance, salinity and low nutrient and water availability generate a gradient of stressful conditions in coastal systems depending on distance to shore. In a tropical coastal system in SE Brazil, we aimed to assess whether Guapira opposita, a shrub common in restinga environments, acted as nurse involved in ecological succession and which factors influenced its facilitation process. We sampled perennial species above 10 cm in height under the canopy of 35 G. opposita individuals and in neighbouring open areas. Shrub height, canopy area and distance to freshwater bodies were measured in the field, and distance to the ocean was obtained from aerial images. In addition, we measured the distance to the closest forest patch as a potential source of seeds. Plant abundance and species richness were higher under the canopy of G. opposita than in open areas. Facilitation by G. opposita was mainly determined by shrub height, which had a positive relationship with woody and bromeliads abundance and species richness while there was no relationship with the other factors. Overall, our data evidence that tropical environments may be highly stressful for plants and that nurse species play a key role in the regeneration of restinga environments, where their presence is critical to maintain ecosystem diversity and function.