Soil phosphorus fractions and their relation to leaf litterfall in a central Amazonian terra firme rainforest

Dos Santos, Emily Darc Andrade, Tng, David Yue Phin, Mattos Guimaraes Apgaua, Deborah, Assunção, Raul Reis, and Manzi, Antônio Ocimar (2022) Soil phosphorus fractions and their relation to leaf litterfall in a central Amazonian terra firme rainforest. Acta Amazonica, 52 (2). pp. 104-113.

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Phosphorus (P) cycling is an important yet poorly studied aspect of the macronutrient balance in tropical rainforest ecosystems. As soil P occurs in different organic and inorganic forms (fractions) with varying degrees of lability, we hypothesized that these fractions will vary between soil types, and temporally within soil types. Additionally, we hypothesized a direct influence of leaf litterfall P input on soil total P and soil P fractions. We collected soil and leaf litter samples from three soil types in a central Amazonian lowland rainforest in Brazil over five months, and used a modified Hedleys fractionation method to determine six organic and inorganic soil P fractions, and also total, labile and residual P. Leaf litterfall P concentrations were determined colorimetrically. Soil inorganic and organic P fractions varied between soil types and across months, but soil type and month interactions were mostly non-significant. Some inorganic P fractions (Pi-NaOH) peaked while the organic fractions (Po-NaOH) fell and vice versa. Leaf litterfall production and leaf litterfall P input peaked around two months following the wettest month. Leaf litterfall P input was a significant predictor of Po-NaHCO3, a bioavailable P fraction. Future studies on P cycling in terrestrial ecosystems should examine the roles played by individual soil P fractions as they cycle asynchronistically and differently across soil types.

A ciclagem de fósforo (P), mesmo sendo pouco estudada, é importante para o equilíbrio de macronutrientes em ecossistemas de floresta tropical úmida. Como P no solo ocorre em diferentes formas orgânicas e inorgânicas (frações), com diferentes graus de labilidade, supomos que essas frações variam temporalmente entre os diferentes tipos de solo. Além disso, hipotetizamos uma influência direta da serrapilheira no aporte de P no solo. Coletamos amostras de solo e folhas em três tipos de solo em uma floresta tropical na Amazônia central no Brasil durante cinco meses e usamos o método de fracionamento modificado de Hedley para determinar seis frações orgânicas e inorgânicas de P no solo, bem como P total, lábil e residual. As concentrações de P na serrapilheira foram determinadas pelo método de colorimetria. As frações de P inorgânico e orgânico do solo variaram entre os tipos de solo e ao longo dos meses, mas as interações entre tipo de solo e meses foram majoritariamente não significativas. Algumas frações de P inorgânicas (Pi-NaOH) atingiram o pico enquanto as frações orgânicas (Po-NaOH) caíram e vice-versa. A produção de serrapilheira e a entrada de P atingiram o pico por volta de dois meses após o mês mais chuvoso. A entrada de P da serrapilheira foi um preditor significativo de Po-NaHCO3, uma fração de P biodisponível. Futuros estudos sobre a ciclagem de P nos ecossistemas devem examinar o papel desempenhado pelas frações individuais de P no solo, à medida que circulam de forma assíncrona e diferente entre tipos de solo.

Item ID: 76603
Item Type: Article (Research - C1)
ISSN: 0044-5967
Keywords: leaf litter, nutrient cycling, tropical soil
Copyright Information: This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Date Deposited: 23 Feb 2023 00:15
FoR Codes: 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310308 Terrestrial ecology @ 50%
41 ENVIRONMENTAL SCIENCES > 4106 Soil sciences > 410604 Soil chemistry and soil carbon sequestration (excl. carbon sequestration science) @ 50%
SEO Codes: 18 ENVIRONMENTAL MANAGEMENT > 1806 Terrestrial systems and management > 180606 Terrestrial biodiversity @ 100%
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