Coss spring 2016

Main objective: Identify key components of the soil food web, and their interactions, that confer stability in soil functions following disturbance events

Controls on the stability of soils and their functioning under land use and climate change

Glensaugh

Yorkshire Dales

Devon

Slow fungal channel

Fast bacterial channel

Mobile higher trophic levels

½ N full N

½ tram

full tram

½ tram ½ tram

½ N

½ N

full N

full N

full tram full tram

Drought shelter

Drought shelter

Drought shelter

Drought shelter

Drought shelter

Drought shelter

Unimproved Improved

x 5

Time

Disturbance

Resilience:Magnitude and speed of return to initial state

Resistance:Immediate response to disturbance

• GHG & respiration• Chemistry• Microbial C• PLFA• Root biomass

• Mycorrhiza

• Soil Biology

MEASUREMENTS

@SoilEcolUoM

Air with 13CO2

Pulse labelling

13CO2 released global activity15N2O, 15N2 nitrification / denitrification activity

C and N flow trough the soil food web components : labelling experiment

Follow the fate of added 15N and 13C in the plant-soil system and quantify the impact of drought and management on the C and N flow through soil food web

15NH415NO3

Soil food web

Plant shootPlant rootsMicroorganismsSoil fauna (detritivores, herbivores, predators)

Measurements :

Extensive / intensive managementDrought / control

Closed chamber

Litter

Litter

Litter

13C Labelling experiment

40 µm meshAllow myceliumExclude roots

0.5 µm meshExclude mycelium and roots

Microorganisms Microorganisms+

Detritivores

Microorganisms+

Detritivores+

Predators

Control vs Drought

3 food webs * 2 treatments * 6 rep = 36 mesocosms

+ 6 for natural isotope abundance 42 mesocosms

13C-CO2

Pulse labelling