Carbon storage in relation to soil size-fractions under tropical tree-based land-use systems

Abstract

The extent of carbon (C) sequestration in soils under agroforestry systems in relation to soil types (fraction sizes) and vegetation structure remains largely unexplored. This study examined soil C storage, an indicator of C sequestration potential, in homegardens (HGs), natural forest, and single-species stands of coconut (Cocos nucifera), rice (Oryza sativa)-paddy, and rubber (Hevea brasiliensis), in Thrissur district, Kerala, India. Soil samples collected from four depth zones up to 1 m were fractionated to three size classes (250 -2000 µm, 53 -250 µm, <53 µm) and their total C content determined. Total C stock (Mg ha −1 ) was highest in forests (176.6), followed by managed treebased systems, and lowest in rice-paddy field (55.6). The results show storage of higher amounts of C in the <53 µm fraction, the most stable form of C in soil, up to one-meter depth, in land-use systems with high stand density of trees such as forests and small-sized HG. Although the results do not allow comparison of changes in soil C stock in different land-use systems, they show higher C storage in soils under tree-based land-use systems compared with the treeless (ricepaddy) system, especially in lower soil depths, suggesting the higher soil C sequestration potential of tree-based systems, and thereby their role in reducing atmospheric concentration of carbon dioxide.

Soil organic carbon contents, aggregate stability, and humic acid composition in different alpine grasslands in Qinghai-Tibet Plateau

“…In general, the labile, resistant and aggregateassociated organic C fractions were also significantly correlated with each other, indicating that they were closely interrelated. On the other hand, our results indicated that the correlation coefficients were lower between SOC with labile C and macro-and micro-aggregate C than between SOC with resistant C and silt and clay sized C. It has been reported that silt and clay sized C was more stable than macro-and micro-aggregate C (Buyanovsky et al 1994;Six et al 2000;Saha et al 2010). Therefore, although labile C fractions have been suggested as early indicators of SOC changes (Haynes et al 2000), the resistant and stable C forms (i.e., humic C and silt and clay sized C) were the main determinant of SOC contents and stocks present in our study region.…”

Black Spruce Soils Accumulate More Uncomplexed Organic Matter than Aspen Soils

“…To the best of our knowledge, this study is the first to specifically address the effect of forest types on SOC stabilization through soil aggregation and soil physical fractions in a natural ecosystem. The very few studies focusing on this topic took place in managed plantation systems (e.g., Blanco-Canqui et al, 2007;Gama-Rodrigues et al, 2010;Quideau et al, 1998;Saha et al, 2010;Sarkhot et al, 2008), where soil disturbance is high and naturally-associated understory is generally lacking. In addition, the tree species selected in these studies were mostly genetically improved species [e.g., loblolly pine {Pinus taeda L.) and hybrid poplar clones].…”

Effects of gravel on grassland soil carbon and nitrogen in the arid regions of the Tibetan Plateau

“…Our study indicated that medium surface cover with~40-50% gravel can provide optimal conditions for increasing SOC and TN stocks in the arid and windy regions. In addition, we did not study litter quality in this paper, but it is well known that the rate of litter decomposition and therefore the SOC content are dependent on plant litter quality, represented mainly by lignin and polyphenol contents and the nature and amount of root exudates (Saha et al, 2010;Xu et al, 2008).…”

“…Most previous studies have focused on the effect of vegetation type and management practices on soil carbon and nitrogen (e.g. Jelinski and Kucharik, 2009;Saha et al, 2010;Smith, 2008;Somaratne et al, 2005;Van Oost et al, 2007). Using gravel as a special mulch above the soil surface may have an important bearing on soil carbon sequestration in arid and semiarid regions by controlling wind erosion of soil, decreasing soil surface evaporation and changing soil physical behavior (Poesen and Lavee, 1994).…”