Phenological responses to climate change based on a hundred years of herbarium collections of tropical Melastomataceae

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.

What triggers phenological events in plants under seasonal environments? A study with phylogenetically related plant species in sympatry

“…Plant phenophases are intimately related to climate (Lieth, 2013) and temperature is one of the main drivers of plant phenology in vegetations worldwide (e.g., tropical forests: Lima et al, 2021;savannas: Vilela et al, 2017). Phenological studies are, therefore, crucial to understand how plant growth and reproduction vary according to climate, especially during the Anthropocene, as shifting phenological events (e.g., early reproduction, late leaf flushing) due to changes in temperature and precipitation regimes might affect plant community structure, associated animals such as herbivores and pollinators (Vilela et al, 2017) and ultimately the provision of ecosystem services (Memmott et al, 2007).…”

Herbarium records provide reliable phenology estimates in the understudied tropics

“…Herbarium specimens also have shown promise in studies of tropical plant phenology but have seen comparatively little use and have yet to be applied broadly (Borchert, 1996;Boulter et al, 2006;Fava et al, 2019;Lima et al, 2021;Zalamea et al, 2011). On this front, recently demonstrated the likely utility of applying massive herbarium data for resolving tropical phenology, especially in Brazil.…”

The fate of Holoregmia, a monospecific genus endemic to the Brazilian Caatinga, under different future climate scenarios

“…In addition, effects on the geographic species distribution, phenological and physiological processes have been predicted to occur (Walther et al 2002;Bellard et al 2012;Shrestha and Bawa 2014) and, more recently, documented. For example, Lima et al (2021) evaluated the reproductive phenological changes of four species of Melastomataceae endemic to the Brazilian Atlantic Forest over almost 100 years, in which the temperature increased continuously and precipitation varied greatly. The authors observed that reproductive phenology is strongly linked to local climatic conditions and detected significant changes in the season as well as in the seasonality of flowering and fruiting of the species.…”