Forest humus forms as potential indicators of soil carbon storage in Mediterranean environments

Abstract

The aim of this work was to investigate the potential of forest humus forms as indicators of soil C storage. To this purpose, Mediterranean forest soils in Southern and Central Italy were examined. Sites differed for elevation, climate, parent material and vegetation conditions, while summer drought was the common ecological factor. A morpho-functional criterion, based on holorganic layers thickness and A horizon properties, was used to classify humus forms, which ranged from Dysmoder to Eumull. Such variability allowed understanding of factors influencing organic matter storage. The relations between carbon stock and humus form were investigated for the topsoil layer (0–20 cm), which was supposed to contain the soil C pools most sensitive to climate change. We found that humus forms can be grouped in statistically different populations, with respect to topsoil C stocks. The use of A horizon structure was the main diagnostic criterion and represented the most effective approach to humus classification in Mediterranean conditions. It appears that humus forms have a clear potential as indicators of organic carbon status in Mediterranean forest soils

Humusica 1, article 8: Terrestrial humus systems and forms – Biological activity and soil aggregates, space-time dynamics

“…The quantity of organic matter fixed in clay aggregates is much more important in Mull systems than in all other humus systems (De Nicola et al, 2004). On the other hand, a similar amount of organic carbon can be measured in different humus systems (Sartori et al, 2004;Garlato et al, 2009a, b;Bonifacio et al, 2011;Ascher et al, 2012;Andreetta et al, 2011). Humus systems and organic carbon contents are relatively independent.…”

News about humus forms

“…A livello dell'equatore umido il sistema dominante è il Mull (Ponge, 200;Bouché, 2014). I sistemi dominanti nelle foreste italiane sono in ordine crescente di copertura i Mull, gli Amphi, i Moder, i Mor e i Tangel; i primi tre coprono più del 90% delle superfici (Hartmann, 1970;Garlato et al, 2009aGarlato et al, , 2009bAndreetta et al, 2011;Bonifacio et al, 2011;Ascher et al, 2012;Guermaldi et al, 2013;De Nicola et al, 2013. Sul suolo di una foresta media europea cadono annualmente circa 5-6 t ha -1 di Carbonio presente nella lettiera (Ponge et al, 1999;Zanella et al, 2001;Gobat et al, 2010;Incerti et al, 2011;Osman, 2013).…”

“…La forma Amphi può essere considerata un sistema doppio: Moder in superficie e Mull in profondità. Tale forma potrebbe essere interpretata come un adattamento del sistema Mull agli ambienti con siccità periodica, come quelli submediterranei presenti in alcune aree delle prealpi (Zanella et al, 2011;Andreetta et al, 2011). In tali situazioni i vermi anecici possono rifugiarsi nelle profondità del suolo per sfuggire alla siccità estiva, pronti poi a risalire in superficie in caso di miglioramento delle condizioni climatiche (piogge autunnali e primaverili) per cibarsi della lettiera.…”

“…The soil fertility strongly depends from them. In Mediterranean forests on the contrary, M ull had the highest stock of OC, near to Amphi and decidedly more (2.5 x) than Moder (Andreetta et al, 2011, De Nicola et al 2014 Amphi was found as the richest in OC in the West wing of the Alpine chain (Bonifacio et al 2011) M oder was at the first place in the Centre (Sartori et al, 2007, Garlato et al, 2009, Ascher et al, 2012 and East (Garlato et al, 2009) Ad est e centro delle alpi sono i sistemi Moder a contenere più carbonio (100 t ha -1 ), a occidente sono gli Amphi (80 t ha -1 , mentre sugli Appennini sono i Mull 80 t ha -1 , anche se vicinissimi agli Amphi). Figure 6.…”

Relationship between soil humus dissimilation, soil biological and chemical properties, and leaf litter characteristics in pure forests

“…As soil humus plays important roles in the soil structure formation, soil permeability and aeration maintenance, nutrient supply and soil carbon sequestration functions, it has attracted much attention in recent decades (Andreetta et al, 2011;Khaled and Fawy, 2011). The existing studies have demonstrated that the humus content and componential properties exhibited considerable specificity in different forests (Dong et al, 2015;Li et al, 1992).…”