Periodic Reporting for period 1 - ANAFAUNA (Implementation of soil fauna effects into the forest ecosystem model ANAFORE)
Période du rapport: 2019-09-01 au 2021-08-31
This dedicated effort was carried out in two different systems: (i) a field mesocosm experiment (REGIMESHIFT) simulating climate change towards more persistent precipitation regimes, (ii) a laboratory mesocosm experiment (EARTHWORM) testing the effect of earthworms on soil structure and C cycling. These matched each other well because the former system contained plants but not earthworms while the latter contained earthworms but not plant roots allowing to disentangle these two sources of macroporosity. Each system was used to test selected assumptions made in the current KEYLINK model.
While several assumptions of the model were supported by the experimental results, some others were not. The results highlight that soil structure is dynamic but cannot be simply estimated from other soil properties such as total or microbial C, roots, fungal or earthworm biomass. Instead, cumulative C inputs or earthworm activity over time might be more important and could be a way forward in modelling aggregation or burrowing in KEYLINK. Furthermore, some interesting and potentially important patterns were observed that will be implemented in KEYLINK, namely the changes in soil water repellency and its impact on infiltration. Altogether, these findings will result in an improved version of KEYLINK. Furthermore, the project brought important evidence of the detrimental effect of persistent precipitation regimes on soil.
In the EARTHWORM experiment, pF water retention curves, earthworm biomass, litter biomass and texture were measured. After four months of the experiment, all litter in treatments with earthworms disappeared from the soil surface confirming the significant influence of earthworms on the carbon cycle. In contrast to the hypothesis, no increase in macroporosity was found using the pF measurements in mesocosms with earthworms. A possible explanation is that the relatively high soil moisture content may have promoted settling. In fact, endogeic earthworms were found to decrease macroporosity and increase bacterial pores, and overall they had a compacting effect on the soil suggesting that their horizontal burrows may facilitate settling more than the mostly vertical burrows created by anecics.
The results of the project were disseminated via three poster presentations at the Biology Research Day (University of Antwerp), World Soil Day (Prague, Charles University) and AGU Fall meeting (San Francisco), one live presentation with virtual display at EGU General Assembly 2021 and one talk at the PLECO research group seminar. Furthermore, two manuscripts for peer reviewed scientific journals are in preparation.