Litter decomposition and nutrient release dynamics of leaves and roots of the babassu palm in eastern Amazonia

Abstract

The ruderal babassu palm (Attalea speciosa) is expanding on large areas of degraded Amazon landscapes. Decomposition of leaves and roots is in the center of plant:soil interactions. We evaluated decomposition and nutrient concentrations of leaves and fine roots of babassu in comparison with two exotic reference species, Acacia mangium (slow degradability) and Leucaena leucocephala (fast degradability), in a 138-day litterbag assay carried out in secondary forest stands of different age and babassu abundance. We chose 4-mm over 2-mm mesh litterbags based on a pilot study. Babassu leaves degraded slower than leaves of A. mangium and L. leucocephala, and also had lower nitrogen, phosphorus and calcium concentrations in all stages of decomposition. By contrast, potassium concentrations in babassu leaves were higher than in both reference species at 0 and 50 days. Roots of all three species decomposed slower than leaves. Compared to the leaves, both biomass loss and nutrient concentrations differed less between babassu and reference-species roots, except for lower nitrogen concentration in babassu roots. Leaf-litter decomposition of all three species was significantly faster in old than in young secondary forest, suggesting an acceleration of decomposition along succession. Babassu leaves decomposed faster in old babassu-dominated than non-dominated secondary forest, pointing to the existence of specialized decomposer communities in babassu-dominated stands.

Soil Chemical Quality in Integrated Production Systems with the Presence of Native and Exotic Tree Components in the Brazilian Eastern Amazon

“…Babassu palm has wi rence in anthropized areas of the Amazon [36]. The high carbon to nitrogen ra and slow decomposition rate of its biomass [24] is generally associated with high lignin [37], whose incomplete decomposition is a precursor in the formation of S The integrated system containing babassu palm (CLFI-II) demonstrated great produce biomass, although it was not uniformly distributed over the soil surface palm has a strategic competitive advantage because of its litter production wi C:N ratio that accumulates around the plants, resulting in an increase in sur…”

“…This species has unparalleled social and economic importance for smallholders in the eastern Amazon due to the exploitation of many products from extractivism [23]. Moreover, this species has great ecological importance because of its resilience and abundance even after vegetation fires and soil degradation in the Amazon [24]. Babassu palm is a ruderal species, with wide occurrence and with a dominance ability in anthropized areas located in the "Arc of Deforestation" of the Amazon.…”

Decomposition, biochemical composition and nutrient cycling of macauba palm in a Cerrado Entisol

“…The maintenance of native plant life is essential to production and environmental conservation (Luz et al, 2020). Plant residue decomposition and nutrient cycling dynamics depend on the plant's biochemical composition and biotic and abiotic factors that may influence soil microbial activity (Carvalho et al, 2012;Zhang et al, 2018).…”

“…During the long dry period in the Cerrado region, the microorganisms are inactive (Borges et al, 2014;Souza et al, 2016), but when the first rains begin (the soil rewets) the "birch effect'' occurs (Birch, 1964;Jarvis et al, 2007;Nijs et al, 2018) which leads to an increase in microbial activity that accelerates the decomposition process, regardless of the water table . Studies that relate the rates of litter decomposition to the biochemical composition of native tropical palms are essential to an understanding of nutrient cycling. However, these studies are limited (Luz et al, 2020) without information on the native macauba population found in parts of the Brazilian Cerrado. We hypothesize that the decomposition process and nutrient cycling in macauba are influenced by its biochemical composition under both low and high water levels.…”

Belowground competition and niche partitioning between the Babassu palm and Urochloa grass in eastern Amazonian pastures

“…Babassu and Urochloa have in common an accumulation of soil organic matter (SOM) in their surroundings, reported for Babassu by Gehring et al (2020), and in Urochloa pastures by Santos et al (2013) and Silva Neto et al (2012). The pathways for such SOM buildup, however, likely differ between the two, with high root exudation from the C4 grass Urochloa (Louw‐Gaume et al, 2017), as opposed to high Babassu litter inputs with high C:N ratios (Gehring et al, 2020) and slow litter decomposition (Luz et al, 2020).…”