Effects of climate on deadwood decomposition dynamics and interaction with the soil in Apennine and Alpine beech forests
Author(s)
Fravolini, Giulia
Date Issued
May 6, 2017
Type
Doctoral Thesis
Abstract
Forests contribute to the sequestration of organic C and a key issue in C cycling in
forest ecosystems can be linked to deadwood dynamics. Deadwood and litter act as
important linkages between forest productivity and current community, and ecosystem
processes. In forest ecosystems, coarse woody debris (CWD) influences the nutrient
cycling, humus formation, carbon storage, fire frequency, water cycling and it
represents also a habitat for many organisms. While a broad range of literature about
CWD decay (above-ground) already exists, mechanisms describing the incorporation of
the woody necromass into humus forms are rather poorly investigated.
The objectives of this thesis are focused on providing a deeper understanding of
deadwood decay processes in forest ecosystems located in the Mediterranean and
Alpine montane areas. Moreover, this research project investigates the relationship
between deadwood decay, altitude and exposure, exploring the decomposition timing in
Apennine and Alpine forests, with the main aim to deeper understand the deadwood
decay processes in these climatic contexts.
In detail, the organic matter integration into the soil was investigated, focusing on the
CWD decay and its incorporation in the soil organic matter (SOM) through the analysis
of the wood biochemical compounds and soil chemical composition.
A climosequence approach was used to investigate the decay processes, comparing
along sites located on north- and south-facing slopes, at different elevations. An
accurate sampling configuration and experimental procedure was set up: at each site of
the climosequence, a field experiment using soil mesocosms (PVC tubes with
deadwood inside) was tested. Data were collected in Apennine (Fagus sylvatica) and
Alpine (Picea abies) forest types, in order to assess the variation of chemical and
biochemical compounds in CWD during the decay progression. Lignin and cellulose
amounts were quantified in 5 different decay stages of CWD in the Alpine sites (Picea
abies and Larix decidua).
Results showed that CWD decompose differently between Alps and Apennines,
depending on the tree species, climate factors and soil composition. In detail, CWD of
Fagus sylvatica decays very fast, while CWD decay progression of Picea abies is
lower, as demonstrated by the analysis of lignin and cellulose in the different 5 decay
stages.
In conclusion, these results represent a contribution to the knowledge on CWD decay
progression in Mediterranean and Subalpine forest ecosystems. However, further
studies are needed to deeper explore the factors influencing the deadwood decay rates,
in order to clarify the role of deadwood in contributing to the overall forest functioning
at different scales.
Additional information
Dottorato di ricerca in Scienze, tecnologie e biotecnologie per la sostenibilità
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