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

laxum (“pombeiral”). Shrublands dominated by C. lanceolatum are flooded at approximately 2 m and for up to 6 months and have some associated species, such as Triplaris gardneriana, a riparian tree. These shrubs initially grow in isolated clumps but gradually form dense mono- specific stands [49]. Alluvial Seasonal Semi-deciduous Forests are located along permanent watercourses and experience periodic flooding for short to long periods depending on their position along the relief gradient [51]. The canopy height can reach 30 m on better-drained riverbanks near run- ning water [46,48,52]. It is among the richest woody species colonized by highly flood-tolerant species, including Garcinia brasiliensis, Mouriri guianensis, Ocotea suaveolens, Siparuna brasi- liensis, Trichilia catigua, Vitex cymosa, and Zygia inaequalis. Lowland Seasonal Semideciduous Forests may appear contiguous to the Alluvial Seasonal Semideciduous Forests along the relief gradient [52] on flood-free or shortly inundated (1–2 months) ridges or paleolevees [53,54]. Many species, such as Anadenanthera colubrina, Aspi- dosperma cuspa, Astronium fraxinifolium, Attalea phalerata, Cordia glabrata, Dipteryx alata, Pseudobombax marginatum, and Tabebuia roseoalba are frequently shared between these types of forests. In these slightly higher-lying areas, differences in water availability may benefit species with greater tolerance to drier conditions, such as Combretum leprosum [55]. Semi-Evergreen Monodominant Forest of Vochysia divergens, known as “Cambarazal”,

is characterized by the monodominance of V. divergens (>50% dominance) which is usually found on young fluvial deposits [52]. The understory is composed of medium to large trees such as Duroia duckei, Leptobalanus parvifolius, and Nectandra amazonum, riparian species phytogeographically linked with Amazon flora [46]. The canopy can exceed 20 m high, creat- ing dense tree cover with a sparse understory where V. divergens seedlings that are either scat- tered or absent. This forest typically develops under a prolonged flood regime, often lasting over six months [47]. In each of these seven communities, one to three plots measuring 5 m x 80 m were used to monitor phenological aspects at the community level, totaling 18 plots and a sampled area of 7.200 m2 (0.72 hectares). In each plot, all woody individuals with a DBH � 5 cm and palms were identified and tagged, and phenological data were recorded monthly, summing 983 indi- viduals belonging to 59 species across 28 families (17 individuals per species on average). The plant species were collected and deposited in the Herbarium of the Federal University of Mato Grosso (UFMT). Since the research was conducted outside protected areas and did not involve endangered species, no data collection permission from official environmental institutions (i.e., Instituto Chico Mendes de Conservac¸ão da Biodiversidade—ICMBio) was required. We identified plants at the species level by comparison with herbarium specimens and with help from taxonomists. Among the 983 individuals, 156 individuals from 14 species were in the PS,

198 individuals from 21 species were in the CS, 138 individuals from 16 species were moni- tored in the IS, 46 individuals from 5 species were in the SHB, 133 individuals from 34 species were in the ASDF, 180 individuals from 30 species were in the LSDF, and 132 individuals from 15 species were in the MF. The number of species in our study plots is similar to tree richness estimates from other phytosociological inventories conducted in the Pantanal [49,55–57]. We identified vegetative and reproductive phenological events through direct observation with binoculars to evaluate the presence or absence (qualitative) and intensity (quantitative) aspects of phenological dynamics. The vegetative phenophase is represented by leaf fall when canopy gaps can be observed or when leafless branches are present [58]. Flowering encom- passes flower buds and anthesis, and the fruiting phase includes green and ripe fruits. Pheno- logical activity and intensity were measured for each vegetation type to evaluate the synchrony, seasonality, and intensity of phenological events in the species populations. The index of phenological activity was assessed through the frequency of individuals in a certain PLOS ONE Phenological cycles in the Pantanal woody communities PLOS ONE | https://doi.org/10.1371/journal.pone.0316011 February 7, 2025 5 / 30