Soil organic matter: Interactions, feedbacks and consequences for soil function, a dynamic modelling framework.

Prof. Bernard Cosby1, Claudia Cagnarini1, David Robinson1, Eleanor Blyth2, Chris Evans1, Rob Griffiths1, Laurence Jones1, Aiden Keith3, Inma Lebron1, Niall MacNamara3, Jeremy Puissant2, Sabine Reinsch1, Ed Rowe1, Simon Smart3, Amy Thomas1, Jeanette Whitaker3, Bridget Emmett1

1Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd, United Kingdom, 2Centre for Ecology and Hydrology, Maclean Building, Crowmarsh Gifford, Wallingford, Oxfordshire, United Kingdom, 3Centre for Ecology and Hydrology, Lancaster Environment Centre, Bailrigg, Lancaster, United Kingdom

Sustainable land management under changing climate requires a modelling framework capable of simulating long-term landscape-scale changes in soil organic matter (SOM). The paradigm shift from SOM recalcitrance as “intrinsic property” to SOM persistence as “ecosystem interaction” suggests decadal-scale SOM models driven by landscape-scale characteristics might capture more realistic spatio-temporal SOM dynamics. We present a soil profile or pedon-explicit, landscape-scale framework for data and models of SOM distribution and dynamics. Landscape-scale drivers are integrated with pedon-scale processes in two zones of influence. SOM in the upper vegetative zone is affected primarily by plant inputs (above and belowground), climate, microbial activity and physical aggregation. Biotic transformations between states/pools are rapid but prone to surface disturbances increasing risk of SOM loss. SOM dynamics in the lower mineral-matrix zone are controlled primarily by mineral-phase and chemical interactions with SOM inputs from the vegetative zone. Biotic transformations are fewer and disturbances less likely producing more favourable conditions for SOM persistence. The thicknesses of the two zones and their transport connectivity are dynamic (time-variable) and affected by plant cover, land use practices, climate and feedbacks from SOM stock in each layer. Vegetative zone boundary conditions vary spatially at landscape scales (vegetative cover) and temporally at decadal scales (climate). Mineral-matrix zone boundary conditions vary spatially at landscape scales (geology, topography) but change only slowly. Consideration of the framework structure identifies critical knowledge needed to advance the emerging paradigm of SOM dynamics. Application of the framework to decadal, data-rich soil monitoring sites with and without land use change in the UK demonstrate emergent scale-dependent responses of SOM to climate and land management changes arising from novel feedbacks included in the model.


Biography: Dr. Cosby has over 40 years of research experience in the U.S., Canada and Europe studying the hydrology and biogeochemistry of soils and natural waters. His research focuses on development of process-based ecosystem models for catchment soils, low-order streams and small lakes, and coastal and estuarine systems. He uses these models for increasing scientific understanding and as tools for knowledge transfer and environmental decision-making.

SOIL ORGANIC MATTER

7th International Symposium
Soil Organic Matter

6 – 11 October 2019

Hilton Adelaide

Adelaide, South Australia

Australia

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