Combined forest and soil management after a catastrophic event

At the end of October 2018,a storm of unprecedented strength severely damaged the forests of the eastern sector of the Italian Alps.The affected forest area covers 42,500 ha.The president of one of the damaged regions asked for help from the University of Padua.After eight months of discussion,the authors of this article wrote a consensus text.The sometimes asper debate brought to light some crucial aspects:1)even experienced specialists may have various opinions based on scientific knowledge that lead to conflicting proposals for action.For some of them there is evidence that to restore a destroyed natural environment it is more judicious to do nothing;2)the soil corresponds to a living structure and every ecosystem’s management should be based on it;3)faced with a catastrophe,people and politicians find themselves unarmed,also because they rarely have the scientific background to understand natural processes.Yet politicians are the only persons who make the key decisions that drive the economy in play and therefore determine the near future of our planet.This article is an attempt to respond directly to the governor of a region who formally and prudently asked a university department called"Land,Environment,Agriculture and Forestry"for help before taking decisions;4)the authors also propose an artistic interpretation of facts(uncontrolled storm)and conclusions(listen to the soil).Briefly,the authors identify the soil as an indispensable source for the renewal of the destroyed forest,give indications on how to prepare a map of the soils of the damaged region,and suggest to anchor on this soil map a series of silvicultural and soil management actions that will promote the soil conservation and the faster recovery of the natural dynamic stability and resilience.

Size fractions of organic matter pools influence their stability: Application of the Rock-Eval® analysis to beech forest soils

Soil organic matter (SOM) is a complex heterogeneous mixture formed through decomposition and organo-mineral interactions, and characterization of its composition and biogeochemical stability is challenging. From this perspective, Rock-Eval® is a rapid and efficient thermal analytical method that combines the quantitative and qualitative information of SOM, including several parameters related to thermal stability. This approach has already been used to monitor changes in organic matter (OM) properties at the landscape, cropland, and soil profile scales. This study was aimed to assess the stability of SOM pools by characterizing the grain size fractions from forest litters and topsoils using Rock-Eval® thermal analysis. Litter (organic) and topsoil samples were collected from a beech forest in Normandy (France), whose management in the last 200 years has been documented. Fractionation by wet sieving was used to separate large debris (> 2 000 μm) and coarse (200–2 000 μm) and fine particulate OM (POM) (50–200 μm) in the organic samples as well as coarse (200–2 000 μm), medium (50–200 μm), and fine (< 50 μm) fractions of the topsoil samples. Rock-Eval® was able to provide thermal parameters sensitive enough to study fine-scale soil processes. In the organic layers, quantitative and qualitative changes were explained by the progressive decomposition of labile organic compounds from plant debris to the finest organic particles. Meanwhile, the grain size fractions of topsoils presented different characteristics. The coarse organo-mineral fractions showed higher C contents, albeit with a different composition, higher thermal stability, and greater decomposition degree than the plant debris forming the organic layer. These results are consistent with those of previous studies that microbial activity is more effective in this fraction. The finest fractions of topsoils showed low C contents, the highest thermal stability, and low decomposition degree, which can be explained by the stronger interactions with the mineral matrix. Therefore, it is suggested that the dynamics of OM in the different size fractions be interpreted in the light of a plant-microbe-soil continuum. Finally, three distinct thermostable C pools were highlighted through the grain size heterogeneity of SOM: free coarse OM (large debris and coarse and fine particles), weakly protected OM in (bio)aggregates (coarse fraction of topsoil), and stabilized OM in the fine fractions of topsoil, which resulted from the interactions within organo-mineral complexes. Therefore, Rock-Eval® thermal parameters can be used to empirically illustrate the conceptual models emphasizing the roles of drivers played by the gradual decomposition and protection of the most thermally labile organic constituents.