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

Abstract

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.

Seasonal litterfall and nutrients in an Atlantic Forest fragment

“…In a transitional region between the Amazonian biome and the Cerrado, in the municipality of Nova Xavantina MT, Peixoto et al (2018) found a significant negative correlation between rainfall and litterfall. The authors evaluated rainfall in two different years and observed that the year with the lowest rainfall provided a significant increase.…”

Meio ambiente e sociedade: análises, diálogos e conflitos ambientais

“…No total, 37 artigos científicos foram contabilizados no período avaliado, porém a maioria amostrou mais de um ecossistema sucessional (BRANDO et al, 2008;PEIXOTO et al, 2018) ou o mesmo ecossistema em idades/tipo de manejo diferentes . As publicações distribuíram-se, principalmente, na porção brasileira do bioma, com destaque para o nordeste paraense (Figura 1).…”

Savanas podem se Transformar Funcionalmente em Florestas na Transição Amazônia/Cerrado

“…These variations observed in the tree community can alter the capacity for assimilation and release of carbon and nutrients in case of ecological succession (i.e. Dense Cerrado turning into Cerradão) (Peixoto et al, 2018). Therefore, studies monitoring the litter layer, leaf decomposition and root mat also become relevant (Hobbie, 2015;Sitch et al, 2015;Oliveira et al, 2017).…”

“…The study areas belong to the set of permanent plots of the CNPq/PELD Project-Amazonia-Cerrado Transition (Mato Grosso State University), RAINFOR-Forest Inventory Network (University of Leeds) and the GEM-Plots (Global Ecosystem Monitoring) (University of Oxford), which investigate floristics, structure, phytosociology, carbon balance and functional aspects of ACT ecosystems, including trophic balance. Soil, floristic and phytosociological surveys were previously carried out by Marimon-Junior & Haridasan (2005), nutrient cycling by Oliveira et al (2017) and carbon flows and ecosystem functionality by Valadão et al (2016) and Peixoto et al (2018). Floristics and phytosociology of vegetation are of dystrophic Cerradão (sensu Ratter et al, 1973) and Typical Cerrado (sensu Ribeiro & Walter, 1998) (Marimon-Junior & Haridasan, 2005).…”

“…Such a condition can favor the expansion of forests over savannas in the ACT under the current climate conditions (Passos et al, 2018), increasing the stocks of carbon and nutrients in the ecosystem (Valadão et al, 2016). On the other hand, this same hyperdynamic equilibrium may be the cause of the vulnerability of this vegetation in case of an increase in the frequency of drought and heat events (Peixoto et al, 2018). Deforestation and fires in the region of ACT known as Arc of Deforestation in the Brazilian agricultural frontier caused a major habitat fragmentation of the tropical world (Garcia et al, 2019;Xu et al, 2020).…”