Understanding the regeneration of Atlantic Forest under climate change: seed germination in response to increased temperatures

Abstract

The Atlantic Forest is a global hotspot of biodiversity and plays a crucial role by providing essential ecosystem services to society. Given the impact of climate change on the ecological dynamics of this biome, it is essential to understand the magnitude of the effects of climatic extremes on processes such as the regeneration of native species. In this study, we investigated how heat waves affects the germination and establishment of 10 species of trees native to the Brazilian Atlantic Forest through a climate chamber experiment. Ten seeds per species were subjected to two dormancy-breaking treatments (with/without) and incubated at two levels of diurnal temperatures (25/35 °C). Seed germination was monitored daily. After the germination phase, up to two seedlings per species were acclimatized for 15 days and subsequently exposed to three heat wave events (40 °C for 72 hours), with a 5-day interval between each event. The impact of heat waves on plant development (i.e., height and leaf number) was monitored weekly. Six species germinated under at least one of the treatments to which they were subjected. Only the identity of the species significantly affected seed germination. The dynamics of the germination process were different between the 25°C and 35°C chambers, but the total number of seeds germinated in the treatments were similar at the end of the 49 days. The species with the best performances were Libidibia ferrea (Mart. ex Tul.) and Copaifera langsdorffii Desf. The heat waves did not affect the survival or development of the plants. We emphasize the need for species-specific studies to understand Atlantic Forest regeneration in the face of future climate changes.