86,607 research outputs found
Forest vegetation and old-fields colonization by woody species in a region of the Julian Prealps, Taipana-Udine
No full textSpecies composition of woody vegetation, density, health, regeneration, evolution trend in the short time and landscape dynamics in recent time (last 50 yr) were studied. Secondary succession models have been described by reconstructing the phases of colonization by forest vegetation in old fields. Fast colonization and success of woody vegetation, particularly Fraxinus excelsior, Alnus glutinosa and Acer pseudoplatanus characterize the process
The impact of pruning and mortality on urban tree canopy volume
No full textUrban trees provide a wide range of ecosystem services for city residents, with tall, mature trees with wide crowns generally regarded as preferable. The tree biomass which is responsible for shading, pollution removal, rain runoff retention etc. gets periodically reduced by the municipal tree management practice of pruning. This is a necessary activity, which reduces the risk of infrastructure damage and falling branches, but many estimates of ecosystem service provision in cities do not consider its impact explicitly. Tree mortality is also higher in cities, preventing trees from attaining and remaining at large sizes. This study used extensive field measurements of tree structure to estimate the impact of pruning on 8 tree species in two Italian cities: Taranto and Florence. Crown widths were reduced by 1.6 m on average, however there is large variation between species variation with branches more often being removed for thinning crowns resulting in larger gap fractions, which increased by 15% on average. No significant differences were observed for crown widths or gap fraction between trees pruned 3 and 4 years previously, suggesting that tree crowns structurally recover from pruning after 3 years. A deterministic model revealed that current urban forest pruning rates (every 6 years) and mortality (1%) may create a situation in which a city dominated by the species studied benefits from 93.5% of the maximum ecosystem services possible. This work will allow more nuanced estimates of urban forest services to be calculated
Thermal comfort and perceptions of the ecosystem services and disservices of urban trees in florence
No full textModern urban lifestyles have most likely generated a loss of awareness of the bio‐cultural benefits derived from the presence of trees and forests in cities. The present study aimed at understanding the level of awareness and the ability to express significant relationships, both positive and negative, on ecosystem services and disservices by the citizens of a Mediterranean city where thermal comfort during the summer period can be particularly problematic. A questionnaire consisting of multiple‐choice and open‐ended questions was disseminated to citizens of Florence, Italy. The open questions allowed respondents space to describe what they perceive are the benefits and dis-benefits of urban trees. Meanwhile, geospatial and climate data were processed in order to check the vegetation and microclimate conditions of the city areas where the 592 respondents live. The vast majority of respondents felt Florence is unbearably hot in summer with 93% agreeing the city needs more trees, and shaded places were perceived as the most important feature of urban green space. The results reveal many positive and negative associations to different species of trees and bring out a rich mosaic of perceptions towards urban green spaces and the features they contain. People are generally aware of a wide range of the benefits trees provide to communities and a good knowledge of the microclimate modification properties was revealed. Many of the popular public tree genera in the city, such as Tilia, Platanus and Pinus were favoured by residents however there was some overlap with trees that provoke negative experiences, and this information can be useful to city planners aiming to maximise ecosystem services and minimise ecosystem disservices
Summer thermal comfort of pedestrians in diverse urban settings: A mobile study
No full textUrban planning must consider the outdoor thermal comfort of city dwellers, particularly in cities where climate and the effects of climate change may severely influence human health and wellbeing in increasingly hot summers. The role of the urban forest in ameliorating this problem is decisive. The present study is based on a campaign of meteorological measurements in a large number of sites using a mobile data collection system to allow a human-centred approach. The aim is to quantify the different microclimates and thermal comfort conditions in six classes of urban morphology, discriminating landtypes with or without trees. In the case study of Florence, local physical characteristics of the sites; Sky View Factor (SVF), tree shade, ground surface cover, and canyon effect, can moderate human exposure to potentially uncomfortable thermal conditions during a typical Mediterranean summer. Significant differences in Universal Thermal Comfort Index (UTCI) were observed between treeless piazzas and streets and landtypes with trees or high height to width ratio (narrow alleys). Varying levels of SVF and tree cover in the sites allowed the construction of multivariate models, which revealed that, during common summer afternoon conditions, decreases of SVF by 12.5% or increases of tree cover by 25% can reduce the UTCI by 1°. Additionally, the total site factor, by incorporating temporally integrated sun exposure with the sky view factor, revealed itself a promising variable for future studies to use
Growth Pattern and Architecture in Quercus Ilex L. and Fraxinus Ornus L. Vegetative Regeneration After Coppicing in Maremma Nature Park (Central Italy)
No full textThe growth pattern and architecture of Quercus ilex L. and Fraxinus ornus L. resprouting after coppicing has been study to test the space occupation dynamics by the new meta-population of shoots. In the early years after coppicing, Fraxinus ornus L. rapidly occupies the vertical space by long spring flushes, while Quercus ilex L. occupies both the vertical and horizontal available space by a complex apical architecture of primary meristems. The two different behaviors have been interpreted as strategic resilience response of the species to environmental disturbances
Ecology of vegetative regeneration after coppicing in macchia stands in central Italy
No full textVegetative regeneration after coppicing of Quercus ilex, Phillyrea latifolia, and Fraxinus ornus in two macchia stands in the Maremma Nature Park (Grosseto, Italy) has been studied. Observations during the first three years after the cut showed that horizontal space occupation by shoots is rapid (95% of the available space being reoccupied within 3 yrs.) and stool mortality very low. We observed differences among species in resprouting, growth pattern and shoot differentiation. Q. ilex and P. latifolia had a longer budburst period than F. ornus. There were no considerable differences in height growth among the three species in the first year. During the second and third years the height increments decreased. F. ornus average height increments were higher than those of Q. ilex and P. latifolia. These two species produced proleptic flushes from the first year on, while F. ornus only showed spring flush. The examination of proleptic shoots and of summer and autumn rainfall seem to show that the latter control Q. ilex growth and shoot differentiation more than that of other species. Differentiation among shoots of the same stool occurs from the first year onwards and the initial vigour differences amongst shoots remain during the following years. Resprouting, space occupation and shoot differentiation have been discussed in relation to rainfall and temperature. The high stool survival and the strong link between stool vigour parameters before and after coppicing confirm a certain stability in successional dynamics following a single coppicing event. © 1992 Kluwer Academic Publishers
Urban Food Forestry: Current state and future perspectives
No full textDiscourses on growing food in cities belong to the wider theme of
the so-called Edible landscapes that represent the integration of food plants within a landscape design. There are many possible and definitions for this, but in general is possible to state that they are the result of the combination of fruit and nut trees, berry bushes, vegetables, herbs, edible flowers, and other ornamental plants into garden designs that may include a variable quantity of edible specimens. Urban Food Forest represent a rather new, way of interpreting edible landscapes with deep roots in the past. The innovative elements are traceable in two key words: forest and permanence
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