Definizione e delimitazione delle Regioni di Provenienza delle specie forestali presenti nei boschi del Lazio e caratterizzazione dei soprassuoli da inserire nel Registro Regionale dei materiali di base
Author(s)
Vessella, Federico
Date Issued
March 11, 2011
Type
Doctoral Thesis
Abstract
The definition of biodiversity can have many interpretations, but generally refers to the
amount of species occurring in an ecosystem: more species, greater stability. At species’ level,
biodiversity is mainly related to the genetic differences between individuals; a rich intra-specific
gene pool means a wide range of responses to environmental strains. On the other hand, populations
with low genetic diversity tend to respond evenly to stress conditions, thus having more difficulties
to face currently growing disturbances driven by anthropic pressure and climate change, especially
on local and regional scales.
Individuals, populations and ecosystems are tightly linked and interact to maintain landscape
stability, large socio-economic systems and man’s health. As consequence, biodiversity
maintenance should be carried out with active conservation measures implemented with the most
recent progress in techniques and policies. For forest species, this implies awareness of the
availability of new and efficient tools to comply with traditional strategies, such as tree populations
management at their natural sites within the environment to which they are adapted (in situ) and
artificial, but dynamically evolving populations, elsewhere (ex situ).
Under these circumstances an operative tool could certainly be the definition and
delimitation of Regions of Provenance, promoted by the European Directive 105/99. The main
methods involved the use of ecological parameters (e.g. pedological, phytoclimatic), presumed to be
homogeneous within each area, thus identifying ecoprovenances for a species as a consequence of
evolutionary differentiation according to the effects of natural selection. They provide a framework
for specifying sources of forest reproductive material, i.e. cones, fruits and seeds, all parts of plants
obtained by vegetative propagation, including embryos and plants produced from any of these. The
plant material from which the forest reproductive material is derived includes seed stands, seed
orchards, parent material held by tree breeders in archives, individual and mixtures of clones.
Nowadays, many European countries are promoting methods to detect Regions of
Provenance, mainly based on chemiophysical parameters, because of the data availability across
years of land monitoring. As result, each country has been divided in several ecologically
homogeneous sub-zones, with fixed boundaries. This could be represent a preliminary approach to
full-fill the Directive’s requirements, but a deeper study is encouraged to focus on each forest
species for which Regions of Provenance are required. Some countries, as France, Spain or
Germany are working since 15 years to provide these results, while Italy is still many steps
backward.
In particular, the Italian position is partially due to its jurisdiction that devolve power in
terms of environmental policy from the central Government to the Regional departments. As
consequence, the definition of Regions of Provenance in our country is still incomplete and in many
cases at preliminary stages.
In the present work, the main goal was to assess a method based on ecological parameters,
like in other European scenarios, to define and delineate Regions of Provenance for Latium in order
to establish seed stands for selected forest species. A first step regarded data collection and analysis
to create the set of most representative chemiophysical variables to point out ecoprovenances; than,
distribution ranges of 28 forest species listed as natural and/or autochthonous for Latium have been
obtained from remote analysis of cartographic dataset or from previous studies. During this process,
10 species were fully mapped, and for the remaining 18 species quantitative ranges were performed
at 1:10000 scale level, with information on presence/absence.
Because of the need to identify seed stands of these species that could also benefit from
legislative pre-existing conditions, only forest surface within protected areas was taken into
account. Totally, a cartographic dossier of 432 maps was produced with information about the
number of sites and hectares for study species in each protected areas of Latium. At the same time,
a case study was afforded to complete the process from the definition of Regions of Provenance up
to seed stands identification. Domestic pine (Pinus pinea L.) stands across Latium coasts were
monitored. Forest stands were mapped, dendrometric and structural characteristics were recorded
during field surveys and detailed information about each stand were summarized in a specific map
set. Overlapping distribution range of domestic pine to the Regions of Provenance previously
performed, two zones were identified as containing all the stands and another one was added
because of the occurrence of one population on the buffer zone. Finally, two pine forests were
chosen as candidate to become seed stands, in order to get one stand for each Region
(Castelporziano for Region 12 “Litorale”, and Foresta del Circeo for Region 9 “Lauretum caldo”).
Forest management proposals were also carried out for these forests, to accomplish guide
lines for the Envirnomental Directorate of Latium in order to perform the best practices to protect
and maintain seed stands and provide certified base material for reforestation programs.
Moreover, mutual points of interest risen up during this work gave the chance to delve into
the present methodologies and theoretical ideas in order to approach innovative and practical tools,
that could be considered as advanced experiments. In particular, a first investigation point out the
use of combined dendroecological and phenological analysis to define Regions of Provenance by
biological parameters. Previous dendroclimatic research demonstrated the relationship between
plant growth and climatic parameters; in Latium, similar bioclimatic responses from different forest
stands growing at similar elevations were statistically grouped into three homogeneous altitudinal
belts using principal component analysis and hierarchical cluster analysis. Phenological patterns of
forest species were quantified using the photosynthetic activity signals expressed in the normalized
difference vegetation index (NDVI). Through a beech tree-ring network, NDVI was compared with
dendroecological results using Geographical Information System analysis, obtaining high
correspondence in overlapping, and underlying the relevance of altitude as a main factor defining
homogeneous spatial vegetation dynamics, thus delimiting ecological Regions of Provenance based
on tree responses to climate.
At the same time, a tentative study was assessed to find a reforestation approach that include
in its theoretical principles the concept of Region of Provenance as an ecologically homogeneous
well-delimited zone. The effectiveness of the Miyawaki method, never tested in Mediterranean
environments was experimented in Sardinia, and point out the possibility to adopt sustainable
techniques in principle with the declarations of the European Directive 105/99, in sites where
traditional reforestation approach failed.
The Miyawaki method has been applied in the Far East, Malaysia, and South America;
results have been very impressive, allowing quick environmental restorations of strongly degraded
areas. However, these applications have always been made on sites characterized by high
precipitation, but never in context with summer aridity and risk of desertification. Results obtained
2 and 11 years after planting are positive: having compared the traditional reforestation techniques,
plant biodiversity using the Miyawaki method appears very high, and the new coenosis (plant
community) was able to evolve without further operative support after planting. Therefore, the
implementation of supplementary technique along with cost reduction might provide a new and
innovative tool to foresters and ecological engineering experts for Mediterranean environmental
reforestation program.
Additional information
Dottorato di ricerca in Scienze e tecnologie per la gestione forestale e ambientale
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