Precipitation Deficits and High Temperature Increase Leaf Litterfall in Open Restinga Vegetation, in Southern Brazil

Abstract

Climate is an important driver of litterfall along different ecosystems. However, little is known about how climate affects litter production in plant communities of Restinga. The aim of this study is to characterize the temporal variation in leaf litter production in an Open Clusia Formation in Restinga de Jurubatiba National Park, from 2001 to 2018, and assess how local variability in litter production reflects the local climatic conditions and its variability. We tested the hypothesis that monthly leaf litterfall increases in dry months and in drier and warmer than average months; we also evaluated if annual leaf litterfall increases in wetter and warmer years following leaf production patterns, that increases in these conditions. We found that litterfall peaks in the drier months. This pattern is consistent for many tropical ecosystems, even evergreen ecosystems, and may have evolved as a strategy that result in reduced water stress by plants, during drier and warmer periods, or may simply be a stress symptom. However, we also found that decreases in monthly rainfall and increases in monthly ∆Temperature (temperature observed minus estimated based on 1970-2000 interval) stimulate leaf litter production. Hot and warmer than average years also seem to stimulate leaf litterfall. It suggests that annual leaf litterfall and leaf production are less affected by precipitation regimes than variations in temperature (or radiation, which is directly related to temperature). It may result from the fact that Clusia hilariana, the dominant species in this ecosystem which accounts to 80 % of leaf litterfall, is a CAM photosynthesis species, a characteristic commonly associated with avoidance of water stress by plants. Although leaf litterfall seems to be predominantly driven by climate at annual scale, only 15 % of its variation was associated to climate at seasonal scale, suggesting that local factors control litterfall at lower temporal scales in Open Clusia Formation.

Bioclimatic predictors of forest structure, composition and phenology in the Paraguayan Dry Chaco

“…While precipitation appears to be the strongest driver of phenology, effects of temperature on phenological events have been observed in other tropical forests. The interaction between temperature and leaf dynamics has been observed in southeast Asia and in south America (Marques et al 2004; da Rocha Gripp et al 2020; Kitayama et al 2021).…”

Dimensões Ecológicas, Geológicas e Humanas em Estudos de Longa-Duração no Parque Nacional da Restinga de Jurubatiba, Rio de Janeiro.

“…é baixo em florestas tropicais (Bruijnzeel 1991), assim como em formações costeiras sazonalmente secas (Jaramillo et al 2011), como as restingas. Nesses ambientes, estima-se que até 90 % de toda a produção primária não seja consumida por herbívoros e, portanto, um grande excedente de matéria orgânica converge para o solo em forma de detritos vegetais (Cebrian 1999), sendo que o folhiço constitui a maior fração dessa matéria orgânica, tanto nas restingas (Gripp et al 2020(Gripp et al , 2023a quanto em âmbito global .…”

“…Nas restingas, a baixa capacidade de retenção de água do solo arenoso pode submeter a comunidade de decompositores a curtos períodos de disponibilidade de água. Dessa forma, apesar de a precipitação não ser baixa (1 100-1 250 mm por ano; Gripp et al 2020) e a estação seca ser pouco marcada, a comunidade de decompositores pode estar submetida a períodos de escassez de água ao longo de todo o ano, o que resultaria em uma baixa taxa de decomposição.…”

Daily Variation on Soil Moisture and Temperature on Three Restinga Plant Formations

“…Besides competitive interactions with C. hilariana, a lower and intermittent water availability at the soil surface to shallow root seedlings may restrict their growth on OCS. It has been previously demonstrated that litterfall rates are correlated to air temperature and precipitation in OCS and, to a lesser extent, in SDF (Brito et al, 2018;Gripp et al, 2020). When temperature increases and rainfall becomes lower than evapotranspiration, soil moisture is depleted, increasing tensions in the xylem sap that can trigger stomatal closure and other physiological responses (Nepstad et al, 2002), limiting tree growth and promoting litterfall peaks (Lawrence, 2005).…”