Trends of litter decomposition and soil organic matter stocks across forested swamp environments of the southeastern US

Abstract

A common idea in the discussion of soil carbon processes is that litter decomposition rates and soil carbon stocks are inversely related. To test this overall hypothesis, simultaneous studies were conducted of the relationship of environmental gradients to leaf and wood decomposition, buried cloth decomposition and percent soil organic matter in Taxodium distichum swamps across the Mississippi River Alluvial Valley (MRAV) and northern Gulf of Mexico (GOM) of the US. Decomposition of leaf tissue was 6.2 to 10.9 times faster than wood tissue. Both precipitation and flooding gradients were negatively related to leaf and wood litter decomposition rates based on models developed using Stepwise General Model Selection (MRAV vs. GOM, respectively). Cotton cloth should not be used as a proxy for plant litter without prior testing because cloth responded differently than plant litter to regional environmental gradients in T. distichum swamps. The overall hypothesis was supported in the MRAV because environments with higher precipitation (climate normal) had lower rates of decomposition and higher percent soil organic matter. In the MRAV, higher levels of percent soil organic matter were related to increased 30-year climate normals (30 year averages of precipitation and air temperature comprising southward increasing Prin-Comp1). Soil organic carbon % in inland vs. coastal T. distichum forests of the MRAV were comparable (range = 1.5% to 26.9% vs. 9.8 to 31.5%, respectively). GOM swamps had lower rates of litter decomposition in more flooded environments. Woody T. distichum detritus had a half-life of up to 300 years in the MRAV, which points to its likely role in the maintenance of inland "teal" soil organic carbon. This unique study can contribute to the discussion of approaches to maintain environments conducive to soil carbon stock maximization.

Quality of soil from the nickel mining area of Southeast Sulawesi, Indonesia, engineered using earthworms (Pheretima sp.)

“…The rate of decomposition of the mineral soil organic matter could be triggered through the presence of the worms (Guo et al, 2019). Through this decomposition, soil organic carbon is emitted in the form of CO2, due to the stock of soil organic matter that would continue to be eroded when not accompanied by external input (Middleton, 2020), such as from plant roots and other organic matter. Dechaine et al (2005) showed that there was a positive correlation between Pheretima sp.…”

Long-Term Carbon Accumulation in Temperate Swamp Soils: a Case Study from Greenock Swamp, Ontario, Canada

“…Contrastingly, recalcitrant material such as lignin-rich wood, are incorporated into soil as structural compounds by physical transfer. For this reason, leaf and stem material is commonly not preserved at depth in swamp soils,whereas woody materialmay remain relatively undecomposed for much longer periods of time and consequently may be found at great depths (Gholz et al 2000;Middleton 2020). The presence of wood can also reduce decomposition of other organic materials present in soil through the leaching of polyphenols, which inhibit microbial metabolism and extracellular enzyme activities (Fenner and Freeman 2020).…”

The role of temperate treed swamps as a carbon sink in southwestern Nova Scotia

“…Bhatti et al (2006) found C stocks to increase along a gradient from uplands to forested peatlands, and Flanagan and Syed (2011) found forested peatland ecosystems to have a C balance of 43 6 12 g C•m -2 •year -1 . A few studies have acknowledged the role of northern temperate treed swamps in the C cycle, but none have examined all in situ parameters of GHG emissions, litterfall, litter decomposition, and soil C. Middleton (2020) measured C stocks and litter decomposition of forested swamps, Miao et al (2017) measured respiration at ecosystem scale, and Trettin and Jurgensen (2002) compiled C component measurements of some treed swamps.…”