Phenological cycles in the Pantanal woody communities: Responses to climate and soil moisture seasonality

Through repeated cycles of drought and a warming climate, the studied area may be sub- jected to changes in species dominance and potential community declines due to elevated tree mortality across various ontogenetic stages [25,50]. Communities characterized by weak responses to rainfall seasonality, such as the LSDF and SHR, are anticipated to experience less impact amidst ongoing climate change. Conversely, communities that quickly adjust to yearly climate patterns may experience more significant impacts. The trajectory of these changes will depend heavily on the species-specific phenological and physiological strategies that plants adopt to cope with drier and warmer climate conditions, as well as disturbances such as fires [130]. Arau´jo et al. (2021) suggested that deciduousness becomes more likely in forest trees, causing a physiognomic shift toward savanna-like vegetation formation [90]. Species that exhibit leaf drop (deciduous) and employ low investment in fruits and seeds (anemochory and autochory) [108] may perpetuate this phenomenon in the context of extended and intense dry seasons, along with reduced flooding [51,88,131]. The replacement of long-lived trees with pioneer trees and lianas is also expected under such climate change scenarios and after wild- fires [25,131]. Even zoochoric tree species, including the caducifolious and pioneer Cerrado species C. americana, may become dominant under drier climate conditions and intensified fire regimes [132]. The interactions between groundwater recharge and surface water dynam-

ics in communities are critical in determining vegetation shifts under climate change scenarios [133]. Nevertheless, the diminished signals for flowering triggered by low temperatures may lead to decreased flowering or the prevention of flowering events in several species [106]. The potential for long-distance dispersal via zoochory and hydrochory across the floodplain is expected to be constrained, which may lead to a reduction in species richness [25] and a decrease in available resources for the diverse fauna found in the Pantanal [28,96,114]. Understanding the selective pressures that shape species’ adaptations to the environment can provide insight into the mechanisms driving ecosystem change and help in conservation and management efforts [134]. Considering the substantial contribution of vertebrates to woody plant dispersal in the Pantanal, the mortality of fauna during wildfires [28] might pose critical concerns to vegetation regeneration and conservation of the diverse mosaics of plant communities in the Pantanal, reducing seedling recruitment [25,135]. The challenges posed by climate change, wildfires, and the potential loss of large-bodied vertebrates necessitate ongoing research, long-term monitoring, and conservation efforts to safeguard the unique biodiversity and ecosystem services offered by the Pantanal. Since the timing of the phenophase is irregular to some degree between years [69], long-term monitoring of phenological cycles could provide additional insight into future scenarios related to climate variability in Pantanal vegetation.

Supporting information S1 Fig. Frequency of woody individuals undergoing leaf shedding, flowering, and fruiting phenological activities throughout an annual hydroclimatic cycle (July 2017 to June 2018). The color gradient illustrates periods of high activity (intense colors) and low activity (softer colors) among individuals. (TIF) S2 Fig. Frequency of woody species in reproductive activity of, A. Flowering activity and B. Fruiting activity, across the annual hydroclimatic cycle for the seven communities. (TIF) S1 Table. Woody species composition and vegetative and reproductive phenology of seven savanna and forest communities of the northern Pantanal. A total of 59 species from 28 families were recorded, totaling 193 individuals in 7,200 m2. The table presents the occupied PLOS ONE Phenological cycles in the Pantanal woody communities PLOS ONE | https://doi.org/10.1371/journal.pone.0316011 February 7, 2025 22 / 30