Assessing the effects of rainfall reduction on litterfall and the litter layer in phytophysiognomies of the Amazonia–Cerrado transition

The tropical vegetation growing in dystrophic soils is capable of recycling nutrients through litterfall and thus maintaining soil fertility. However, climate changes can alter this production and, consequently, the litter layer over the soil, affecting the carbon cycle and the integrity of the ecosystem. In this study, we investigated whether a reduction in rainfall increased the litterfall and the litter layer (stock) and, if so, whether the effects are more evident in degraded environments. We compared the litterfall and the litter layer in years with higher (1575.3 mm) and lower (1360.8 mm) rainfall rates in three environments: “cerradão” (CD; savanna woodland), typical “cerrado” (savanna-like vegetation) and successional area (SA). We recorded increasing litterfall in the SA and in the litter layer in the three environments during the year with lower rainfall rates. We also detected alterations to the seasonal variation in the litter layer and the production of reproductive parts. The reduction in rainfall increased the return of carbon to the soil, especially in open areas. Our results indicate that climatic extremes (e.g., reduced rainfall) can modify the availability of nutrients and their absorption by plants and therefore compromising important ecosystem functions, such as carbon cycle.