35 research outputs found

    Leaf anatomy and ultrastructure in senescing ancient tree, Platycladus orientalis L. (Cupressaceae)

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    Platycladus orientalis L. (Cupressaceae) has a lifespan of thousands of years. Ancient trees have very high scientific, economic and cultural values. The senescence of ancient trees is a new research area but is poorly understood. Leaves are the primary and the most sensitive organ of a tree. To understand leaf structural response to tree senescence in ancient trees, experiments investigating the morphology, anatomy and ultrastructure were conducted with one-year leaves of ancient P. orientalis (ancient tree >2,000 years) at three different tree senescent levels (healthy, sub-healthy and senescent) at the world’s largest planted pure forest in the Mausoleum of Yellow Emperor, Shaanxi Province, China. Observations showed that leaf structure significantly changed with the senescence of trees. The chloroplast, mitochondria, vacuole and cell wall of mesophyll cells were the most significant markers of cellular ultrastructure during tree senescence. Leaf ultrastructure clearly reflected the senescence degree of ancient trees, confirming the visual evaluation from above-ground parts of trees. Understanding the relationships between leaf structure and tree senescence can support decision makers in planning the protection of ancient trees more promptly and effectively by adopting the timely rejuvenation techniques before the whole tree irreversibly recesses

    Producing Urban Aerobiological Risk Map for Cupressaceae Family in the SW Iberian Peninsula from LiDAR Technology

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    Given the rise in the global population and the consequently high levels of pollution, urban green areas, such as those that include plants in the Cupressaceae family, are suitable to reduce the pollution levels, improving the air quality. However, some species with ornamental value are also very allergenic species whose planting should be regulated and their pollen production reduced by suitable pruning. The Aerobiological Index to create Risk maps for Ornamental Trees (AIROT), in its previous version, already included parameters that other indexes did not consider, such as the width of the streets, the height of buildings and the geographical characteristics of cities. It can be considered by working with LiDAR (Light Detection and Ranging) data from five urban areas, which were used to create the DEM and DSM (digital elevation and surface models) needed to create one of the parameters. Pollen production is proposed as a parameter (α) based on characteristics and uses in the forms of hedges or trees that will be incorporated into the index. It will allow the comparison of different species for the evaluation of the pruning effect when aerobiological risks are established

    Systematic method for monitoring and early-warning of garden heritage ontology used in the Suzhou classical garden heritage

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    Taking garden heritage ontologies as the object, this paper explores monitoring and early-warning methods of heritage based on fuzzy cluster analysis. A monitoring and early-warning system for garden heritage ontologies is designed and consists of monitoring indexes, a monitoring program, monitoring data collection, application of an early-warning grading evaluation model and conclusion of early-warning grading. Taking the Suzhou classical garden heritage as an example, it can be concluded that the systematic method can integrate various qualitative and quantitative index values and collectively reflect the overall state of garden heritage ontologies as well as match a heritage monitoring ontology with an early warning grade by calculating the data similarity matrix, membership matrix, fuzzy similarity matrix, fuzzy equivalent matrix and  cut matrix. Five kinds of heritage ontologies with a total of twenty-seven heritage monitoring indicators are applied in the model and then be matched with MATLAB software to obtain accurate early-warning results. When types of heritage ontology need to be expanded, the heritage is further refined, or the heritage is more comprehensive, this method is applicable

    Evolution de la résistance à la cavitation chez les conifÚres

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    Forests worldwide are at increased risk of widespread mortality due to intense drought under current and future climate change. In particular, conifer species seem extremely vulnerable to mortality due to hydraulic failure or embolism. The main objective of this thesis was to examine conifer resistance to embolism in an evolutionary framework. Firstly, we uncovered 9-fold variation in resistance to embolism across 250 species from the 7 conifer families, culminating in a new world record in Callitris tuberculata (P50 = -18.8 MPa). We demonstrated the evolutionary relationship between increased embolism resistance and the anatomy of bordered pits. By combining this unprecedented physiological dataset with a time-calibrated phylogeny of over 300 species, we retraced conifer diversification and the evolution of embolism resistance. We discovered multiple evolutionary dynamics with several conifer lineages shifting to higher rates of speciation and trait evolution. We found that conifers with high drought resistance diversified more rapidly, especially crown groups of Cupressaceae composed of the Cupressus-Juniperus clade and the Callitris clade. Within this last group, diversification rates increased over the course of the aridification of Australia over the last 30 million years. We show how their xylem has been shaped by drought, becoming more resistant to embolism, but crucially we found no trade-off with water transport efficiency or construction costs. This work greatly expands our understanding of how vascular plants have evolved to cope with extreme drought.Les forĂȘts du monde entier sont menacĂ©es de mortalitĂ©s importantes lors de sĂ©cheresses intenses liĂ©s au changement climatique. Les conifĂšres en particulier semblent extrĂȘmement vulnĂ©rables Ă  la mort par dysfonctionnement hydraulique de leur systĂšme vasculaire ou embolie. Le principal objectif de cette thĂšse est d’étudier la rĂ©sistance Ă  l’embolie des conifĂšres dans un cadre Ă©volutif. PremiĂšrement, nous avons mis en Ă©vidence que la rĂ©sistance Ă  l’embolie varie d’un facteur neuf sur plus de 250 espĂšces parmi les 7 familles de conifĂšres, atteignant un nouveau record du monde avec Callitris tuberculata (P50 = -18.8 MPa). Nous avons montrĂ© le lien Ă©volutif entre cette rĂ©sistance et l’anatomie des ponctuations arĂ©olĂ©es. En combinant cette base de donnĂ©es unique avec une phylogĂ©nie calibrĂ©e de plus de 300 espĂšces, nous avons retracĂ© la diversification des conifĂšres et l’évolution de leur rĂ©sistance Ă  l’embolie. Nous avons dĂ©couvert que plusieurs lignĂ©es de conifĂšres ont brusquement changĂ© de dynamiques Ă©volutives, avec l’accĂ©lĂ©ration de la spĂ©ciation et de l’évolution de rĂ©sistance Ă  l’embolie. En outre, les conifĂšres plus rĂ©sistants se sont diversifiĂ© plus rapidement, notamment les genres Cupressus, Juniperus et Callitris (Cupressaceae). La diversification de ces derniers s’est accĂ©lĂ©rĂ©e avec l’aridification de l’Australie sur les derniers 30 Millions d’annĂ©es. Nous montrons que leur xylĂšme a Ă©tĂ© façonnĂ© par la sĂ©cheresse, devenant plus rĂ©sistant Ă  l’embolie mais surtout sans compromettre l’efficience du transport de l’eau ou augmenter son coĂ»t de construction. Cette thĂšse Ă©largit notre comprĂ©hension de l’évolution des plantes vasculaire face aux sĂ©cheresses intenses

    SPATIAL AND TEMPORAL DYNAMICS OF ROOT REINFORCEMENT IN ALPINE FORESTS

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    Protection forests represent an effective tool to prevent and mitigate hydrogeological instabilities and are object of renewed interest in the European Alps, where there is a long history of cohabitation between people and natural hazards. The quantification of the effects of forests against the different types of natural hazards is however still a challenge, and represents a key step for the implementation of an integrated protection strategy able to combine engineering structures with forests. Forests provide different protection mechanisms depending on the type of natural hazards we consider. The aim of this work is to give a contribution to the quantification of the effects of forest vegetation against shallow landslides. Mechanical reinforcement of soil given by root systems is considered the most important contribution of alpine forests against shallow landslides. Many studies proved that it plays a key role in slope stability, but its quantification is still a challenge due to the huge variability that characterizes root reinforcement values. Understanding and modeling this variability is a key step in the development of stability models able to account for the role of vegetation, and to provide practical guidelines to foresters involved in the management of protection forests. Root mechanical reinforcement depends primarily on the density and distribution of roots of different diameter class (i.e. number and size of roots) and on their mechanical properties. Both these factors are subject to a huge variability in natural slopes. We can distinguish a spatial variability, due to the different environmental and stand characteristics that influence root systems development, and a temporal variability, due to the anthropic or natural disturbances that modify the forest stand and as consequence the root systems. The first section of this work presents a review on the role of forests against shallow landslides and the state of the art of the studies on root reinforcement, the models used for its quantification and its implementation in the stability models. The second section deals with the spatial variability of root reinforcement at both the regional and stand scale. The variability of root mechanical properties in several alpine species is analyzed basing on a wide data base obtained by laboratory tensile tests on roots coming from different forest sites in northern Italy, and a possible criterion for the interpretation and synthesis of this variability is proposed. The influence of both root mechanical properties and root distribution variability on the estimation of root reinforcement is then assessed in the case of a common alpine species, Picea abies, by means of the Root Bundle Model. Results show the importance of micro variability of root distribution at the stand scale that heavily affects root reinforcement estimation; the variability of root mechanical properties on the other hand cannot be ignored because it can lead to important errors in root reinforcement estimation. In the third section of the work the temporal dynamics of root reinforcement as consequence of logging activities are studied with intensive field work carried out in two different case of study, two mixed Silver fir \u2013 Norway spruce stands in the Italian Alps and four Norway spruce stands in the Swiss Alps. New experimental data for the quantification of root reinforcement decay after cutting for the selected species are provided, paying attention to both root mechanical properties and root distribution. A model for the estimation of root reinforcement decay that takes into account both the processes is proposed. Results show the importance of modeling horizontal root distribution in the study on root reinforcement decay and underline the need of further research on the role of natural regeneration in stabilizing gaps after cutting

    Urban Forests and Landscape Ecology

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    Urbanization is a dominant driver of landscape transformation across the world, with cities representing centers of economic and socio-cultural development. Today, more than 4.2 billion people live in urban areas, which represent ~3% of the Earth’s land area. By 2050, it is predicted this number will increase to 6.6 billion people (~70% of the predicted global population). As the human population grows, cities around the globe will continue to expand, increasing the demand for food and services. Within cities, urban forests provide multiple nature-based solutions, as well as other environmental services and socio-economic benefits, such as heat mitigation and social integration. Urban forests are also important for coping with psychological stress during events, such as the COVID-19 pandemic. Therefore, urban forests are a priority for basic and applied forest research because they are intimately connected with people’s physical, cultural, and economic well-being in the urban environment, and can also be important reservoirs of biodiversity. To promote a better understanding of urban forests and landscape ecology, this book in “Urban Forests and Landscape Ecology” compiled research set in urban forests and focused on some spatially explicit processes. Studies presented in this book are highly interdisciplinary and use a wide range of research approaches. This book present nine scientific publications from global urban forests demonstrating that these forests, as a nature-based solution, provide multiple environmental services and are crucial to improve urban livability and thereby the wellbeing of city dwellers

    Impacts, Monitoring and Management of Forest Pests and Diseases

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    Forest pests have diverse negative impacts on forestry economy, ecosystem services, biodiversity, and sustainable ecosystem management. The first step towards effectively managing forest pests would be to monitor their occurrence and assess their impact on forest ecosystems. The monitoring results can provide basic information for effective management strategies. The data from monitoring programs can result in the development of new methods for monitoring, assessing impact, and developing management techniques. This special issue aims to share information to assist in the effective management of forest pests, by understanding the responses of forest pests to natural and anthropogenic changes, and discussing new studies on the monitoring, assessment, and management of forest pests. The fourteen papers included in this issue focus on monitoring, assessing, and managing forest pests, including one editorial providing an overall idea of the monitoring, assessment and management of forest pests, two articles reviewing long-term changes in forest pests and forests, four papers focusing on the monitoring of forest pests, three papers on the assessment of forest pests, and four papers on the management of forest pests. These papers provide a better understanding of the structures and processes in forest ecosystems and fundamental information for the effective management of forest pests

    Applications of Remote Sensing Data in Mapping of Forest Growing Stock and Biomass

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    This Special Issue (SI), entitled "Applications of Remote Sensing Data in Mapping of Forest Growing Stock and Biomass”, resulted from 13 peer-reviewed papers dedicated to Forestry and Biomass mapping, characterization and accounting. The papers' authors presented improvements in Remote Sensing processing techniques on satellite images, drone-acquired images and LiDAR images, both aerial and terrestrial. Regarding the images’ classification models, all authors presented supervised methods, such as Random Forest, complemented by GIS routines and biophysical variables measured on the field, which were properly georeferenced. The achieved results enable the statement that remote imagery could be successfully used as a data source for regression analysis and formulation and, in this way, used in forestry actions such as canopy structure analysis and mapping, or to estimate biomass. This collection of papers, presented in the form of a book, brings together 13 articles covering various forest issues and issues in forest biomass calculation, constituting an important work manual for those who use mixed GIS and RS techniques

    ASSESSING SHALLOW LANDSLIDE SUSCEPTIBILITY OF VEGETATED HILLSLOPES THROUGH A PHYSICALLY-BASED SPATIALLY-DISTRIBUTED MODEL

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    Slope instabilities are a serious threat to human activities, settlements, and safety worldwide. Among the different types of slope movement, shallow landslides are the most common phenomena and are often associated to other soil instabilities and to various channel processes (i.e. sediment transport, woody debris). Vegetation and in particular forests is an effective and well-known tool in preventing and mitigating hydrogeological hazards, mainly through the effects of the reinforcement exerted by the root systems. Root reinforcement, then, is a factor that should be included in hazard estimation and the resulting maps that represent a fundamental tool for planning and managing the hydrogeological hazards. Accordingly, in the last two decades, a wide number of different methods and approaches have been proposed to produce landslide hazard maps, with particular reference to Physically-Based Spatially-Distribute Models, PBSDM. However, including root reinforcement is still a challenge for the scientific community due to the huge spatial and temporal variability and the difficulties in incorporating into slope stability analysis. The main gaps to be filled can be summarized as follows: \uf0b7 the knowledge on the spatial distribution of the soil reinforcement due to the root systems have to be improved and linked to the stand forest characteristics; \uf0b7 a 3-D probabilistic PBSDM of hillslope failure able to include in a comprehensive but simple manner the presence of the forest vegetation have to be developed; \uf0b7 the use of information at coarse spatial resolution, which introduces an additional source of uncertainty has to be properly managed. This study gives a brief review of the role of forests against natural hazards and on the state of the art concerning the implementation of root reinforcement into stability models. Thereafter, it attempts to fill such gaps improving the knowledge about modelling and quantifying the effects of vegetation on slope stability. The main outcome is the development of a 3-D probabilistic PBSDM of hillslope failure, based on geotechnical sound hypothesis and stochastic approach through the Monte Carlo Simulation (MCS) analysis. Such a model is able to manage the uncertainty of model parameters and is a reliable way to deal with the problem of a lack, or a poor knowledge of terrain characteristics over large study areas. In addition, it allows evaluating the effects of silvicultural operations, to estimate the woody material, recruitable from the hillslopes in small mountainous catchments, and to quantify the additional soil reinforcement provided by some cultivations such as the grapevine. Moreover, a series of field experiments on the rooted-soil under compression is presented in order to investigate the hydro-mechanical process that occurs during the triggering mechanisms of shallow landslides. Finally, the proposed modelling framework will allow: \uf0b7 to assess the probability of hillslopes failure considering the characteristic of the vegetation and to provide more reliable shallow landslide hazard maps at catchment scale; \uf0b7 to improve the efficiency of prevention and protection due to vegetation, and particularly to the forests, against natural hazards evaluating different land management strategies; \uf0b7 to support the planning of eventual forest interventions or soil-bio engineering works identifying the areas affected by high landslide susceptibility
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