Litter Manipulation Effects on Soil Carbon Dynamics

Manipulating the quantity and quality of plant litter through experimental addition or removal offers critical insights into the pathways that govern soil carbon storage and flux. Litter inputs constitute the primary conduit of organic matter from vegetation to soil, where they fuel microbial activity, shape soil microclimate and influence the formation of stable soil organic carbon pools. Enhanced litter addition often elevates soil respiration and dissolved organic carbon, reflecting both direct breakdown of fresh organic inputs and priming of older soil organic matter. In contrast, litter exclusion suppresses microbial biomass, reduces CO₂ efflux and can deplete labile carbon pools in surface horizons. The magnitude and direction of responses depend on ecosystem type, litter quality and successional stage: tropical soils with rapid organic matter turnover and limited mineral association show little net gain in carbon despite large litter inputs, whereas temperate and subtropical forests can exhibit strong increases in microbial activity and soil carbon stocks under enhanced litterfall. Understanding these processes is essential for predicting terrestrial carbon feedbacks to climate change and for designing forest management strategies that optimise carbon sequestration.

Research from Nature Portfolio

Long-term addition experiments in lowland tropical forest have revealed that more than a decade of doubled litterfall leads mainly to accumulation of readily bioavailable carbon, with no increase in mineral-associated organic matter and even a loss of weakly bound soil carbon fractions. This finding underscores the limited capacity of rapidly cycling tropical soils to stabilise extra plant inputs. In subtropical successional forests, contrasting litter treatments conducted over multiple years showed that litter exclusion reduced soil respiration by around one-third, while doubling litter inputs increased CO₂ efflux by more than two-thirds. The strength of these effects varied with forest age and reflected shifts in soil moisture and microbial community structure. In a mixed-wood temperate forest, multi-year trials comparing leaf and woody litter inputs demonstrated that the presence of leaf litter markedly increased microbial biomass carbon, enzyme activities and soil organic carbon, indicating that litter quality mediates the balance between carbon release and stabilisation.

Litter Manipulation Effects on Soil Carbon Dynamics publication trend

The graph below shows the total number of articles in litter manipulation effects on soil carbon dynamics across all publications each year (not limited to Nature Index journals).

Technical terms

Soil respiration: The total flux of CO₂ from soil to the atmosphere, originating from microbial decomposition of organic matter and root respiration.

Priming effect: A process by which fresh organic inputs stimulate microbial decomposition of pre-existing soil organic matter, leading to enhanced CO₂ release.

Labile carbon: Organic compounds in soil that are readily decomposed by microorganisms, including dissolved organic carbon and simple sugars.

Microbial biomass carbon (MBC): The total mass of living microbial cells in soil, serving as an indicator of microbial activity and nutrient cycling potential.

Mineral-associated organic matter (MAOM): Soil organic carbon that is bound to mineral surfaces or incorporated into aggregates, often more resistant to decomposition.

References

1. Tropical forest soil carbon stocks do not increase despite 15 years of doubled litter inputs. Scientific Reports (2019).
2. Different soil respiration responses to litter manipulation in three subtropical successional forests. Scientific Reports (2015).
3. Soil microbial responses to forest floor litter manipulation and nitrogen addition in a mixed-wood forest of northern China. Scientific Reports (2016).
4. Effect of soil microorganisms and labile C availability on soil respiration in response to litter inputs in forest ecosystems: A meta‐analysis. Ecology and Evolution (2020).
5. Effects of root dominate over aboveground litter on soil microbial biomass in global forest ecosystems. Forest Ecosystems (2021).
6. Distinct responses of soil respiration to experimental litter manipulation in temperate woodland and tropical forest. Ecology and Evolution (2018).