Tree Species Effects on Soil C Dynamics in Temperate Forests

Medina Barcenas, Eduardo Enrique (2018). Tree Species Effects on Soil C Dynamics in Temperate Forests. MPhil thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.00012766

Abstract

Terrestrial ecosystems account for two-fifths of the total exchange of CO₂ between the earth and the atmosphere, with forests contributing 80% of that exchange. Forest biomass and forest soils are particularly important carbon (C) sinks, however forest soil C stocks can vary widely, depending on the dominant tree species. Species specific differences in the quality and quantity of plant litter inputs can influence soil C dynamics and storage because they control decomposition processes, altering soil respiration and soil properties. However, our knowledge of how tree species identity influences the interactions between decomposition processes, soil C dynamics and soil C storage is still deficient. Resolving this knowledge gap is important to determine how tree species selection for afforestation might help us increase soil C sequestration and mitigate the effects of climate change. Using microcosm experiments and in situ mesocosms, I studied interactions between litter quality and soil properties for different temperate tree species in the UK. I measured key litter properties, and quantified the effect of litter quality and quantity on soil CO₂ efflux and soil properties. My results show that litter quality, represented by nitrogen and lignin content, plays a major role in regulating soil C dynamics via litter decomposition. Litter quality also modified changes in soil CO₂ efflux in response to altered litter inputs but the effect varied strongly by species. Using reciprocal transplant experiments in single species stands of alder, oak, and pine, I demonstrate variable influences of litter quality and the ‘home field advantage’ on decomposition and soil CO₂ efflux. The present work provides an insight into the linkages between litter quality, decomposition and soil respiration in temperate forests. My results represent an important first step in identifying the future role of different tree species on soil C dynamics under climate change, which could inform forestry rotation and reforestation practices.

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