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

Rainfall remained below 40 mm month-1 from May to September, triggering leaf fall. Most communities presented strong negative correlations between rainfall and leaf fall intensity, with correlation coefficients above 75% for PS, IS, CS, MF, and ASDF (Fig 6). The influence of rainfall on leaf fall intensity occurred up to one month before the event in some communities, such as the IS (r1 = -0.62, p = 0.02) and PS (r1 = 0.63, p = 0.02) communities. Unlike the other meteorological variables, increased insolation positively influenced leaf fall phenology in open canopy communities, such as the IS (r0 = 0.67, p = 0.01), PS (r0 = 0.57, p = 0.04), and CS (r0 = 0.56, p = 0.04) (Fig 6). Leaf fall intensity in the seasonal alluvial forest (ASDF) was also posi- tively correlated with increased insolation in dry months (r0 = 0.57, p = 0.04). There was no significant correlation between the soil moisture content and the leaf fall cycle in any of the communities, although the soil moisture showed expressive seasonal variation in most of the sampled vegetation (Fig 2). Flowering. The influence of seasonality on meteorological variables and its correlation with flowering intensity varied between communities (Fig 6). In the SHB community, annual variability in soil moisture triggered flowering events, with flowering occurring in August and September, when the soil moisture dropped below 5%, and the mean (29˚C) and maximum (37˚C) temperatures reached their peak. The impact of evapotranspiration was observed with

a two-month delay (r1 = -0.62, p = 0.02). Insolation had a positive effect on flowering one month prior to the event (r1 = 0.59, p = 0.03) and a negative effect in the two months preceding it (r2 = -0.61, p = 0.03). In PS and IS, an increase in insolation hours coincided with more intense flowering events (PS: r0 = 0.57, p = 0.04; IS: r0 = 0.56, p = 0.05). The minimum temperature had a strong influ- ence on flowering events in PS (r0 = -0.74, p = 0.004), suggesting that cold fronts can trigger flower blooming. The cyclical change in weather significantly influenced the flowering cycles in the MF, IS, and PS communities, aligning with trends in various meteorological variables (Fig 6). For example, a reduction in evapotranspiration was associated with an increased percentage of flowering in the MF (r0 = -0.86, p < 0.001), IS (r0 = -0.71, p = 0.003), and PS (r0 = -0.70, p = 0.01) stands. Increased insolation enhanced bloom coverage in the IS (r0 = 0.56, p = 0.05) and PS (r0 = 0.57, p = 0.04) communities. Additionally, reduced maximum tem- peratures significantly affected the flowering intensity in the two months preceding the event. In the CS, flowering intensity was weakly correlated with climate seasonality. The decrease in maximum temperature two months prior to the reproductive event was associ- ated with increased flowering intensity (r2 = -0.60, p = 0.03). Notably, the months leading to the peak of flowering were characterized by cooler temperatures of 5˚C cooler. Finally, the peak flowering periods in the ASDF (r2 = 0.62, p = 0.02) and LSDF (r2 = 0.61, p = 0.03) for-

ests were linked to increased rainfall in the two preceding months, marking transitions from wet to dry periods. Fruting. Climate seasonality had limited influences on fruiting phenology. No correlation was found with soil moisture. Only in the SHB and MF, communities subjected to prolonged flooding (> 3 months, Fig 2), did the fruiting intensity correlate with weather variables. In the SHB, the maximum temperature (r0 = 0.56, p = 0.04) during the phenological event and insola- tion one month prior (r1 = 0.64, p = 0.02) were positively correlated with the fruiting percent- age of the Fournier index, whereas insolation two months prior (r2 = -0.55, p = 0.05) was negatively correlated. In the MF treatment, the mean temperature (r0 = 0.57, p = 0.04) posi- tively influenced fruiting, with higher mean temperatures two months earlier triggering high- intensity fruiting events (r2 = 0.57, p = 0.04). PLOS ONE Phenological cycles in the Pantanal woody communities PLOS ONE | https://doi.org/10.1371/journal.pone.0316011 February 7, 2025 17 / 30