Mechanisms of Carbon Sequestration in Highly Organic Ecosystems – Importance of Chemical Ecology

Abstract

Organic matter decomposition plays a major role in the cycling of carbon (C) and nutrients in terrestrial ecosystems across the globe. Climate change accelerates the decomposition rate to potentially increase the release of greenhouse gases and further enhance global warming in the future. However, fractions of organic matter vary in turnover times and parts are stabilized in soils for longer time periods (C sequestration). Overall, a better understanding of the mechanisms underlying C sequestration is needed for the development of effective mitigation policies to reduce land-based production of greenhouse gases. Known mechanisms of C sequestration include the recalcitrance of C input, interactions with soil minerals, aggregate formation, as well as its regulation via abiotic factors. In this Minireview, we discuss the mechanisms behind C sequestration including the recently emerging significance of biochemical interactions between organic matter inputs that lead to C stabilization.

Proanthocyanidin Biosynthesis—a Matter of Protection

“…Leaf PAs represent a potentially large sink of carbon for greenhouse gas sequestration, but, before attempting to implement increasing PAs as a carbon-reduction strategy, it will be important to consider further their impacts on nutrient recycling, microbial communities, and greenhouse gas emissions from soil. Furthermore, because of the increasingly realized importance of root PAs for soil carbon sequestration (Adamczyk et al, 2020), more studies are required on the biosynthesis of PAs in roots and the effects of their structural modification on the stabilization of organic matter.…”

Dual activity of anthocyanidin reductase supports the dominant plant proanthocyanidin extension unit pathway

“…In addition, the nonspecific protein binding properties of PAs affect forage quality ( 6 , 7 ) and taste and storage life of beverages ( 8 , 9 ). PAs also protect plants against herbivory ( 10 ) and may contribute to carbon capture and soil nitrogen recycling ( 11 ). The lack of full understanding of PA biosynthesis limits our ability to manipulate PA structures in plants to enhance nutritional value, organoleptic properties, forage quality, herbivore resistance, and environmental sustainability.…”

How do boreal forest soils store carbon?

“…[66] A potentially less significant role of OM-mineral interactions in the organic layers of boreal forest soil may stem not only from the lower content of minerals but also from the formation of chelates with Al and Fe by root-derived polyphenolics, thereby potentially inhibiting the interaction with OM. [67] Recently, the assumption that mineral-associated C is protected from microbial decomposition over millennial time scales has been challenged. It has been proposed that common root exudates low molecular mass organic acids like oxalic acid, and citric acid liberate organic C from mineral associations.…”

“…[ 66 ] A potentially less significant role of OM‐mineral interactions in the organic layers of boreal forest soil may stem not only from the lower content of minerals but also from the formation of chelates with Al and Fe by root‐derived polyphenolics, thereby potentially inhibiting the interaction with OM. [ 67 ]…”