Fine root biomass and root length density in a lowland and a montane tropical rain forest, SP, Brazil

Abstract

root biomass and root length density in a lowland and a montane tropical rain forest, SP, Brazil. Biota Neotrop. 11(3): http://www.biotaneotropica.org.br/v11n3/en/abstract?article+bn03411032011Abstract: Fine roots, <2 mm in diameter, are responsible for water and nutrient uptake and therefore have a central role in carbon, nutrient and water cycling at the plant and ecosystem level. The root length density (RLD), fine root biomass (FRB) and vertical fine root distribution (VRD) in the soil profile have been used as good descriptors of resource-use efficiency and carbon storage in the soil. Along altitudinal gradients, decreases in temperature and radiation inputs (depending on the frequency of fog events) may reduce decomposition rates and nutrient availability what might stimulate plants to invest in fine roots, increasing acquisition of resources. We evaluated the seasonal variation of fine root parameters in a Lowland and Montane forest at the Atlantic Rain Forest. We hypothesized that, due to lower decomposition rates at the Montane site, the FRB and RLD at soil surface will be higher in this altitude, which can maximize the efficiency of resource absorption. FRB and RLD were higher in the Montane forest in both seasons, especially at the 0-5 layer. At the 0-5 soil layer in both sites, RLD increased from dry to wet season independently of variations in FRB. Total FRB in the top 30 cm of the soil at the Lowland site was significantly lower (334 g.m -2 in the dry season and 219 g.m -2 in the wet season) than at the Montane forest (875 and 451 g.m -2 in the dry and wet season, respectively). In conclusion, despite the relevance of FRB to describe processes related to carbon dynamics, the variation of RLD between seasons, independently of variations in FRB, indicates that RLD is a better descriptor for studies characterizing the potential of water and nutrient uptake at the Atlantic Rain Forest. The differences in RLD between altitudes within the context of resource use should be considered in studies about plant establishment, seedling growth and population dynamics at the Atlantic Rain Forest. At the ecosystem level, RLD and it seasonal variations may improve our understanding of the Atlantic rain forest functioning in terms of the biogeochemical fluxes in a possible scenario of climate change and environmental changes. Resumo: Raízes finas, <2 mm de diâmetro, são as principais responsáveis pela absorção de água e nutrientes e, portanto, têm um papel central nos ciclos carbono, água e nutrientes, desde o nível da planta até o ecossistêmico. A densidade do comprimento radicular (DCR), a biomassa de raízes finas (BRF) e a distribuição vertical de raízes finas (DVR) no perfil do solo têm sido utilizados como bons descritores da eficiência no uso de recursos e de estocagem de carbono no solo. Ao longo de gradientes altitudinais, a diminuição da temperatura e da radiação solar (dependendo da frequência de eventos de neblina) podem reduzir as taxas de decomposição e disponibilidade de nutrientes, o que poderia estim...

Dynamic niche partitioning in root water uptake facilitates efficient water use in more diverse grassland plant communities

“…Similar dynamics were repeatedly observed on single plants (e.g. Doussan et al., ; Garrigues et al., ; Lai & Katul, ; Rosado et al., ) and is in accordance with models of root water uptake (Bechmann et al., ; Doussan et al., ; Schneider et al., ). For instance, Doussan et al.…”

“…Similar dynamics were repeatedly observed on single plants (e.g. Doussan et al, 2006;Garrigues et al, 2006;Lai & Katul, 2000;Rosado et al, 2011) and is in accordance with models of root water uptake (Bechmann et al, 2014;Doussan et al, 2006;Schneider et al, 2009). For instance, Doussan et al (2006) showed that the contribution of different parts of the root system to total water uptake changes dynamically with time and depends on hydraulic properties and arrangement of the root system.…”

“…However, several studies show that root water uptake profiles may shift independently of root length distribution Hamblin & Tennant, 1987). This is because root water uptake is also related to root hydraulic properties (Kulmatiski & Beard, 2013;Kulmatiski, Beard, Verweij, & February, 2010;Nimah & Hanks, 1973), soil salinity, soil water distribution (Doussan, Pierret, Garrigues, & Pagès, 2006;Garrigues et al, 2006;Van der Ploeg, Gooren, Bakker, & de Rooij, 2008), the amount of fine roots, and the architecture of root systems (Javaux, Couvreur, Vanderborgth, & Vereecken, 2013;Nepstedt et al, 1994;Rosado et al, 2011;Schneider et al, 2009;Williams et al, 1998) as well as the transpiration of leaves (Jackson, Sperry, & Dawson, 2000;Quijano, Kumar, Drewry, Goldstein, & Misson, 2012;Steudle, 2000). For example, Rossatto, Sternberg, and Franco (2012) found that herbs are higher stomatal conductance in more diverse mixtures, contributed disproportionately to dynamic niche partitioning in root water uptake.…”

Different Patterns Of Nutrient Cycling In Contiguous Phytophysiognomies Of Atlantic Forest, Brazil

“…Garay et al (1995) found that approximately 30% of the fine roots of the plants growing in the Mussununga area were present in the litter standing stock, however this was not observed in the Mata Alta. The presence of fine roots (78-94% of total) in the topsoil (0.00-0.05 cm) in tropical forests (Rosado et al, 2011) represents an important mechanism linked to the optimization of nutrient absorption through direct absorption from decomposing litter. This ecological mechanism minimizes nutrient losses through leaching, especially in nutrient-poor sandy soils, thus favoring their retention in the ecosystem.…”

Description of the soil and root biomass of two subtropical mangroves in Antonina and Guaratuba Bay, Paraná State, Brazil

“…Among the root systems of mangroves, fine roots (roots < 2mm of diameter; Rosado et al 2011) play an important function in nutrient cycling because they make a great contribution to the dynamics of belowground phytomass. Fine roots are directly related to soil respiration, mycorrhiza activities and water and nutrient absorption, especially phosphorous (Kummerow et al 1990).…”