Yuri Gori

Stand structure is one of the most important parameters in making forest inventories. When following normal procedures, forestry technicians must identify and map stand structure, and carry out a forest inspection to distinguish homogeneous areas. This is very time-consuming and expensive, and, in addition, often suffers from the subjectivity of foresters, who mainly rely on their expertise to describe forest stands. The aim of the study presented here was to develop a novel method based on a Random Forest algorithm to automatically identify forest structure using LiDAR-derived data (CHM).

<p>* <i>p</i> < 0.05;</p><p>**<i>p</i> < 0.01;</p><p>*** <i>p</i> < 0.001</p><p>Variable selection was made by <i>F</i>-test.</p><p>Summary of multiple regression models for δ<sup>18</sup>O, δ<sup>2</sup>H and δ<sup>13</sup>C.</p

<p>The A column shows those computed without trends, B indicates variograms detrended by a linear model, and C shows those detrended by a quadratic model. The lags have been binned over all directions and incremented in steps of 2,500 m. Solid lines show the models fitted to the variograms with the parameters reported in each panel. The fitted models were chosen on the basis of the smallest RSS, as reported in the text.</p

Tracking timber is necessary in order to prevent illegal logging and protect local timber production, but there is as yet no suitable analytical traceability method. Stable isotope ratios in plants are known to reflect geographical variations. In this study we analysed four stable isotope ratios in order to develop a model able to identify the geographic origin of Norway spruce in the European Alps. δ18O, δ2H, δ13C and δ15N were measured in bulk needles of Picea abies sampled in 20 sites in and around the European Alps. Environmental and spatial variables were found to be related to the measured isotope ratios. An ordinary least squares regression was used to identify the most important factor in stable isotope variability in bulk needles. Spatial autocorrelation was tested for all isotope ratios by means of Moran's I. δ18O, δ2H and δ15N values differed significantly between sites. Distance from the coast had the greatest influence on δ2H, while latitude and longitude were stron...

ABSTRACT We report for the first time a tree-ring isotopic analysis on host trees infected with Heterobasidion parviporum. By measuring carbon and oxygen stable isotope ratios in tree rings over ca. 150 years of forest growth, we obtained evidence that stomatal conductance increases in Picea abies affected by H. parviporum. We put forward this approach as a novel way of providing an insight into plant–pathogen relationships during tree life.

<p>Pooled standard deviations were:</p><p>0.52 for δ<sup>18</sup>O; 3.07 for δ<sup>2</sup>H; 0.90 for δ<sup>13</sup>C; 0.61 for δ<sup>15</sup>N</p><p>Longitude and latitude were determined by GPS. Mean values and standard deviations are reported for each stable isotope value (N = 5). Site codes are as reported in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0118941#pone.0118941.g001" target="_blank">Fig. 1</a>.</p><p>Sampled sites and related mean stable isotope values.</p

Local timber is still one of the main sources of work and income for mountain communities. However, illegal logging is a major cause of deforestation in many countries and has significant impacts on local communities and biodiversity. Techniques for tracing timber would provide a useful tool to protect local timber industries and contribute to the fight against illegal logging. Although considerable progress has been made in food traceability, timber provenance is still a somewhat neglected research area. Stable isotope ratios in plants are known to reflect geographical variations. This study reports accurate spatial distribution of δ18O and δ2H in timber from north-eastern Italy (Trentino) in order to trace geographical origin. We tested the accuracy of four kriging methods using an annual resolution of δ18O and δ2H measured in Picea abies. Pearson's correlation coefficients revealed altitude to be the most appropriate covariate for the cokriging model, which has ultimately pro...

Tree-ring patterns of Picea abies (L.) Karst. both unaffected and affected by Heterobasidion parvipo-rum were analysed in three mature stands located at dif-ferent elevations in the Eastern Alps. The main objectives were (1) to clarify the role of climatic conditions on infected trees; (2) to estimate indirect volume losses due to the prolonged presence of the fungus within the wood. The low elevation site showed the highest growth decline in the last decade, whereas all infected trees at medium and high elevation showed a slow growth decline over many dec-ades. We hypothesise that infection could be dated over 80 years at the highest site. Fungal attack made P. abies more susceptible to drought stress at low elevation site. Both infected and healthy P. abies at medium and high elevation showed similar climate–growth relationships, suggesting that the same driving environmental factors influence their growth. At low elevation, H. parviporum was seemingly more aggressive, causing a m...

Although the links between plant physiological processes and stable isotopes in tree rings are well known, few studies have carried out stable isotope analyses in stressed plants. The general objective of this thesis is to develop new tools able to identify the short- and long-term responses of plants to fungal attack and insect feeding. I propose a new methodology, which uses stable isotope values as indicators of physiological responses and which was tested on infected and defoliated Norway spruce trees sampled in the south-eastern Alps. The thesis is divided into four main sections. In the first section, I present a model designed to accurately estimate environmental proxies for Picea abies, which would serve as the basis for further analyses. This model required calibration and assessment of the effects of climate on the stable isotope signature in different wood components. For this purpose, I developed a simple model to reconstruct mean annual temperature in the south-eastern ...

Although the links between plant physiological processes and stable isotopes in tree rings are well known, few studies have carried out stable isotope analyses in stressed plants. The general objective of this thesis is to develop new tools able to identify the short- and long-term responses of plants to fungal attack and insect feeding. I propose a new methodology, which uses stable isotope values as indicators of physiological responses and which was tested on infected and defoliated Norway spruce trees sampled in the south-eastern Alps. The thesis is divided into four main sections. In the first section, I present a model designed to accurately estimate environmental proxies for Picea abies, which would serve as the basis for further analyses. This model required calibration and assessment of the effects of climate on the stable isotope signature in different wood components. For this purpose, I developed a simple model to reconstruct mean annual temperature in the south-eastern Alps. I found that δ18O and δ2H values in whole wood were the best signallers of climate. The second section is aimed at clarifying the influence of environmental conditions on Norway spruce suffering from long-term infection by the white-rot fungus Heterobasidion parviporum. I found that at low elevations, where climatic conditions are unsuitable, H. parviporum was seemingly more aggressive, causing plants to decline more rapidly, decreasing the ability of host trees to cope with drought and, in some cases, arresting cambial activity. In the third section, I propose using stable isotope ratios as a physiological indicator of Norway spruce affected by H. parviporum over a long period of time and put this forward as a novel way for providing insights into plant–pathogen relationships. I obtained evidence that stomatal conductance increases in Picea abies affected by H. parviporum. The fourth section focuses on stable isotope ratios and tree-ring chronologies to investigate the short- and long-term effects of defoliation of Picea abies caused by Cephalcia arvensis. I found that drought stress prior to insect attack may have caused the trees to mobilise reserves, making them more susceptible to Cephalcia attack as a result of increased soluble sugars and amino acids

In this study we used a tree ring-proxy analysis to analyse the impact of the fungus Heterobasidion parviporum causal agent of root and butt rots of conifers. This fungal pathogen is causing the most economically serious damages in the conifer forests and many studies have been carried out to estimate the wood losses of this disease. However, a significant gap of knowledge is still present on the growth failure caused by this pathogen. The aim of this study was to test the potential of tree ring analysis to estimate the missing growth due to H. parviporum infection on Norway spruce. Three Norway spruce mature stands infected by H. parviporum were selected for sampling in the South-Eastern Alps: Baselga (BAS), Val Maggiore (VAL) and Cermis (CER) at different altitude respectively at 850-900, 1,300 and 1,950 m a.s.l. Health (HT) and infected trees (IT) were sampled. The main goals of the study were: (1) to clarify the role of climate conditions on infected trees by analyzing the clima...

Although the links between plant physiological processes and stable isotopes in tree rings are well known, few studies have carried out stable isotope analyses in stressed plants.
The general objective of this thesis is to develop new tools able to identify the short- and long-term responses of plants to fungal attack and insect feeding. I propose a new methodology, which uses stable isotope values as indicators of physiological responses and which was tested on infected and defoliated Norway spruce trees sampled in the south-eastern Alps.
The thesis is divided into four main sections.
In the first section, I present a model designed to accurately estimate environmental proxies for Picea abies, which would serve as the basis for further analyses. This model required calibration and assessment of the effects of climate on the stable isotope signature in different wood components. For this purpose, I developed a simple model to reconstruct mean annual temperature in the south-eastern Alps. I found that δ18O and δ2H values in whole wood were the best signallers of climate.
The second section is aimed at clarifying the influence of environmental conditions on Norway spruce suffering from long-term infection by the white-rot fungus Heterobasidion parviporum. I found that at low elevations, where climatic conditions are unsuitable, H. parviporum was seemingly more aggressive, causing plants to decline more rapidly, decreasing the ability of host trees to cope with drought and, in some cases, arresting cambial activity.
In the third section, I propose using stable isotope ratios as a physiological indicator of Norway spruce affected by H. parviporum over a long period of time and put this forward as a novel way for providing insights into plant–pathogen relationships. I obtained evidence that stomatal conductance increases in Picea abies affected by H. parviporum.
The fourth section focuses on stable isotope ratios and tree-ring chronologies to investigate the short- and long-term effects of defoliation of Picea abies caused by Cephalcia arvensis. I found that drought stress prior to insect attack may have caused the trees to mobilise reserves, making them more susceptible to Cephalcia attack as a result of increased soluble sugars and amino acids

Stand structure is one of the most important parameters in making forest inventories. When following normal procedures, forestry technicians must identify and map stand structure, and carry out a forest inspection to distinguish homogeneous areas. This is very time-consuming and expensive, and, in addition, often suffers from the subjectivity of foresters, who mainly rely on their expertise to describe forest stands. The aim of the study presented here was to develop a novel method based on a Random Forest algorithm to automatically identify forest structure using LiDAR-derived data (CHM).

RATIONALE
Carbon, hydrogen and oxygen (C, H and O) stable isotope ratios of whole wood and components are commonly used as paleoclimate proxies. In this work we consider eight different proxies in order to discover the most suitable wood component and stable isotope ratio to provide the strongest climate signal in Picea abies in a southeastern Alpine region (Trentino, Italy).
METHODS
δ13C, δ18O and δ2H values in whole wood and cellulose, and δ13C and δ2H values in lignin methoxyl groups were measured. Analysis was performed using an Isotopic Ratio Mass Spectrometer coupled with an Elemental Analyser for measuring 13C/12C and a Pyrolyser for measuring 2H/1H and 18O/16O. The data were evaluated by Principal Component Analysis, and a simple Pearson's correlation between isotope chronologies and climatic features, and multiple linear regression were performed to evaluate the data.
RESULTS
Each stable isotope ratio in cellulose and lignin methoxyl differs significantly from the same stable isotope ratio in whole wood, the values begin higher in cellulose and lignin except for the lignin δ2H values. Significant correlations were found between the whole wood and the cellulose fractions for each isotope ratio. Overall, the highest correlations with temperature were found with the δ18O and δ2H values in whole wood, whereas no significant correlations were found between isotope proxies and precipitation.
CONCLUSIONS
δ18O and δ2H values in whole wood provide the best temperature signals in Picea abies in the northern Italian study area. Extraction of

We report for the first time a tree-ring isotopic analysis on host trees infected with Heterobasidion parviporum. By measuring carbon and oxygen stable isotope ratios in tree rings over ca. 150 years of forest growth, we obtained evidence that stomatal conductance increases in Picea abies affected by H. parviporum. We put forward this approach as a novel way of providing an insight into plant–pathogen relationships during tree life.