Fine root production and distribution in the tropical rainforests of south-western Cameroon: effects of soil type and selective logging

Abstract

© iForest -Biogeosciences and Forestry IntroductionThe tropical rainforests of southern Cameroon as African rainforests are subjected to deforestation due to shifting cultivation, commercial timber and forest exploitation (Archard et al. 2002). This is stimulated by demographic and economic crisis forces. To counteract this process, the Cameroonian government has decided to develop, through the Tropenbos Cameroon Programme (TCP), methods and strategies for sustainable management of his rainforests (Foahom & Jonkers 1992). Fine roots are one of the factors to take into consideration in sustainable forest management, because of their critical role in nutrient cycling and tree regeneration (Saterson & Vitousek 1984). No information on roots is currently available for the tropical rainforests of southern Cameroon, especially on their changes among forest types and the rate of their recovery after selective logging.Because of their high nutrient absorption capacity and quick turnover, fine roots (0.5 to 2 mm diameter) play a key role in nutrient cycles (Castellanos et al. 2001). These roots tend to concentrate in the upper layers of the soil containing most of the nutrients released from decomposing litter. It is therefore a nutrient conservation mechanism in forests (Jordan 1991). Fine roots which are dynamic components of below-ground biomass represent about 30% of the above-ground biomass (Noordwijk et al. 1996) and between 40 and 85% of the net primary production according to the soil type (Hoffmann & Usoltsev 2001). The mortality and decomposition of fine roots contribute substantially to the carbon and nutrients stock in the soil. This contribution is equivalent (or even higher) to that of litterfall that returns carbon and nutrients from canopy to the soil (Hendrick & Pregitzer 1993).Most of the research on fine roots has been carried out in the temperate region (Vogt et al. 1986). However, available information on tropical forests, even though insufficient, show that fine root biomass is higher in tropical forests (4.5 -92.5 t ha -1 ) than in the temperate ones (0.5 -13.0 t ha -1 -Noij et al. 1993). Root biomass assessments as well as the study of root distribution in forest were very studious processes (Hendricks et al. 2006) because of the difficulty involved in sampling and extraction (Noij et al. 1993, Hoffmann & Usoltsev 2001. Moreover, contrary to the situation in temperate forests, where the period of dead vegetation material including roots and turnover are asynchronous, the production and mortality of fine root occur simultaneously, making it difficult to distinguish between living and dead roots.The aim of the present work is to assess the change of fine root biomass and their nutrient content in three undisturbed forests, developed on different soil types according to soil Taxonomy-USDA and differed also by soil chemical characteristic as K, Mg and Ca amount (t ha -1 ) and available P and water content (Van Gemerden & Hazeu 1999). The rate of fine root and their nutrient recovery after selective l...

Fine‐root exploitation strategies differ in tropical old growth and logged‐over forests in Ghana

“…Often, studies that have compared fine-root biomass and architectural and morphological traits in other tropical regions (Table S1) have revealed contrasting dominance of root traits in forests at different recovery stages. Contrary to our findings, comparative studies in the tropics have usually reported higher total fine-root biomass in old growth (unlogged) forests than in logged forests (Hopkins et al 1996, Leuschner et al 2009, Ibrahima et al 2010, Barbhuiya et al 2012, Gautam & Mandal 2012. However, in broad-leaved evergreen subtropical forests in southeast China, Lin et al (2015) reported higher total fine-root (diam.…”

“…, Ibrahima et al . , Barbhuiya et al . , Gautam & Mandal ) and a few fine‐root architectural and morphological traits (Hopkins et al .…”

“…Tropical forest structure and plant species composition change during post-logging recovery (Chazdon 2014, Cazzolla Gatti et al 2015, which may also induce shifts in root dynamics (Leuschner et al 2009, Barbhuiya et al 2012. Most studies that have quantified root dynamics during tropical forest succession have focused on fine-root biomass (e.g., Hertel et al 2007, Ibrahima et al 2010, Barbhuiya et al 2012, Gautam & Mandal 2012 and a few fine-root architectural and morphological traits (Hopkins et al 1996, Leuschner et al 2009, Hansson 2014. These studies have mainly reported higher fine-root biomass, but lower values for fine-root morphological traits (SRL and SRA) in old growth (unlogged) forests than in logged-over forests (Hopkins et al 1996, Hertel et al 2003, Leuschner et al 2009).…”

Effect of disturbance on biomass, production and carbon dynamics in moist tropical forest of eastern Nepal

“…Despite this requirement, most of the past studies in tropical forests are found to be limited to analyzing the aboveground systems (Chave et al 2008;Djomo et al 2011;Malhi et al 2011;Doughty et al 2013;Ngo et al 2013;Girardin et al 2014;Malhi et al 2014) and only a few studies concern to the belowground aspects (Ibrahima et al 2010;Powers and Perez-Aviles 2013;Noguchi et al 2014).…”

Does degradation from selective logging and illegal activities differently impact forest resources? A case study in Ghana

“…The West African forest belt is a biodiversity hotspot and a provider of fundamental ecosystem services, now degraded and reduced to a patchwork of forest fragments (CEPF 2003). Selective logging is possibly the primary cause of degradation in African forests with recognized impacts on carbon stocks (Cazzolla Gatti et al 2015, Hawthorne et al 2012) and fine root production (Ibrahima et al 2010). In Ghana, concessions interest more than half of the reserves (Hawthorne & Abu-Juam 1995).…”