Quantificação de raízes finas em um povoamento de <i>Pinus taeda</i> l. e uma área de campo em Cambará do Sul, RS

Abstract

RESUMOOs objetivos do trabalho foram quantificar e comparar a densidade e a biomassa de raízes finas (≤ 2,0 mm) na serapilheira e nas camadas de 0-10, 10-20, 20-30, 30-40 cm ao longo do perfil de solo, em um povoamento de Pinus taeda L., com 15 anos de idade, e em uma área de campo adjacente. A obtenção das amostras de raízes, foi realizada partindo da escavação de monolitos. As raízes foram separadas do solo por meio de lavagem e catação e, na sequência, foram distribuídas sobre uma folha de papel branca, em que, com o auxílio de uma câmera digital, foram obtidas imagens. Com o auxilio do software Image Tool for Windows version 3.00© as imagens foram processadas para quantificação do comprimento das raízes. Após, as raízes foram secas e, depois, pesadas para determinação da biomassa. A vegetação presente na área de campo apresenta uma densidade de raízes finas 234,28% maior que a área adjacente onde encontra-se o povoamento de Pinus taeda L. Palavras-chave: Pinus taeda; campo; raízes finas; biomassa. ABSTRACTThe objectives of this study were to comparatively quantify length and biomass of fine roots (≤ 2.0 mm) in the soil profile (0-10, 10-20, 20-30, 30-40 cm) and in the litter of a 15-year-old Pinus taeda L. stand, as well as in an adjacent Grassland area. The samples were obtained through monolith excavation. Roots were separated through washing and collecting and were then distributed over a white sheet of paper, where images were obtained with a digital camera. Using the software Image Tool for Windows version 3.00© the images were processed to quantify root length. Subsequently, roots were dried in a stove and, weighed to determine the biomass. The vegetation in the Grassland area showed 234.28% greater density of fine roots than the adjacent area where the Pinus taeda L.stand is located.

Alterações no carbono orgânico do solo de campo natural submetido ao plantio de <i>Pinus taeda</i> em três idades

“…The higher TOC content in the uppermost layer and its decrease with depth agrees with the normally observed pattern in soils under forests of the genus Pinus, as reported by Balbinot et al (2003), Mafra et al (2008) and Butnor et al (2017). This trend is mainly due to the turnover of fine roots with a diameter of ≤ 2 mm, which grow at a higher concentration in the surface layer, usually to a depth of 0.1 m (LOPES et al, 2010), and contributes decisively to OC accumulation in the soil (HUANG et al, 2011;PERSSON, 2012). On the soil surface of these forests, significant amounts of residues are generally deposited from the above-ground part of the trees, forming the litter.…”

“…In general, the POC contents also decreased with depth, especially in the soil under P21, where the contents in the layers differed more clearly from each other. This decrease was expected because POC originates mainly in the more recently decomposed residues that occur in greater quantity in the soil layer around 0.10 m below the surface (LOPES et al, 2010;HUANG et al, 2011). The long-term absence of soil tillage, which was the case in the more mature forests of this study, also favors accumulation in the POC fraction, since soil aggregation is preserved and, consequently, the physical protection of SOM particles within the aggregates (SOLLINS et al, 1996;BAYER et al, 2004).…”

“…The substitution of the natural grassland with predominantly grass species by pine plantations modifies the dynamics of soil organic matter (BALDOCK;NELSON, 2000;LOPES et al, 2010;DICK et al, 2011). This may alter the levels and stocks of organic carbon (OC) accumulated in this environment (BUTNOR et al, 2017).…”

“…In pine forests, the large majority of OC is accumulated in the plant biomass (RICHTER et al, 1999;WATZALAVICK;SANQUETTA;CALDEIRA, 2005;HUANG et al, 2011;SAMUELSON et al, 2017). However, these forests can also accumulate significant amounts of OC in the soil, mainly derived from the turnover of fine roots (LOPES et al, 2010;HUANG et al, 2011;PERSSON, 2012) and residues of dead leaves and branches, forming the forest litter (BALDOCK;NELSON, 2000;CORREIA;ANDRADE, 2008).…”

Edaphic and Topographic Factors and their Relationship with Dendrometric Variation of Pinus Taeda L. in a High Altitude Subtropical Climate

“…In relation to SoD, the trees tend to produce longer roots in soils with low availability of water and nutrients, even though the largest amount of root absorption in pine trees occurs in the top 0.30 m of soil (Lopes et al, 2010). Thus, a hierarchical mechanism for controlling the distribution of photoassimilates between source and drain determines a preferential contribution to the development of the root system in detriment of increasing height (Gonçalves and Mello, 2000).…”