Abstract
Changes in phenological events have been vastly documented in face of recent global climate change. These studies are concentrated on temperate plants, and the responses of tropical species are still little understood, likely due to the lack of long-term phenological records in the tropics. In this case, the use of herbarium specimens to gather phenological data over long periods and wide geographic areas has emerged as a powerful tool. Here, we used four Melastomataceae species endemic to the Brazilian Atlantic Forest to evaluate phenological patterns and alterations as responses to recent climate changes. Phenological data were gathered from Reflora Virtual Herbarium specimens collected between 1920 and 2018, and analyzed with circular statistics applied to the intervals 1920–1979, 1980–1999, and 2000–2018. The effects of temperature range, average temperature, precipitation, and photoperiod on flowering and fruiting of each species were tested using multiple linear regressions. Through circular statistics, we detected changes, mostly delays, in the flowering of Miconia quinquedentata, Pleroma clavatum and P. trichopodum, and in the fruiting of M. acutiflora, P. clavatum and P. trichopodum. We also found that flowering and fruiting occurrence were related to local climatic conditions from months prior to the collections. We found marked phenological variations over the decades and also that these variations are associated to global climate change, adding up to the large body of evidence from higher latitudes. Our results also support herbarium collections as an important source for long-term tropical phenological studies. The lack of consistent patterns of responses among the four species (e.g. fruiting delayed two months in P. clavatum and advanced one month in M. acutiflora) suggests that climate change has unequal effects across tropical forests. This highlights the urgent need for further research to understand and forecast the ecological implications of these changes in global ecosystems processes.
Highlights
Phenology can be summarized as the study of the timing of life cycle events, such as production of flowers and fruits [1]
We aimed to evaluate reproductive phenological changes of four Melastomataceae species endemic to the Brazilian Atlantic Forest along nearly 100 years, and how these changes can possibly be related to the global climate change
By analyzing >650 herbarium specimens with multiple statistical tests, we detected changes in both timing and seasonality of flowering and fruiting over the decades, which are likely to cause direct biological impacts in populations and communities
Summary
Phenology can be summarized as the study of the timing of life cycle events, such as production of flowers and fruits [1]. The seasonal weather in this region leads to a wellmarked reproductive period (generally following warmer temperatures and longer day lengths) followed by a resting period (generally along colder temperatures and shorter day lengths), suggesting that in these areas, temperature and photoperiod play major roles in phenology [4]. This evident pattern facilitates the long-term monitoring of phenology, a crucial point to analyze how climatic variations are affecting plant life cycle [5]. Several studies have shown that temperate plants are flowering earlier with global warming [e.g. 6,7], but delayed flowering has been reported [e.g. 8]
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