Geodaysit 2023

Calamai S., Francesconi A. and Cinelli F.
Department of Energy, Systems, Territory and Construction Engineering, Largo Lucio Lazzarino, Pisa, University of Pisa
The aim of this paper is to highlight the main benefits of using the Qfield app in tree census activity. The advantage of entrusting all of the information to the main GIS platform of the project, which is stored inside the PC, means this leaves only the task of checking the collected data, along with the bonus of in-depth topographical and geospatial analysis. We illustrate the results of tree census activity in the state road 67 Tosco-Romagnola (SS 67) that connects Pisa with Marina di Ravenna, particularly in the stretch that connects the town of Fornacette with Pontedera. Part of this stretch (about 1,.7 km) belongs to the Municipality of Calcinaia with which we are collaborating for the urban tree inventory. This one is straight, has a discontinuous and partly uneven double row of trees of the same species (hackberry), and is subject to high vehicular traffic, even heavy, due to the presence of artisanal and industrial activities. The goal of the work was to evaluate the phytopathological and hazardous conditions and the ecosystem benefits of the trees along this stretch of road in terms of healthy, C02 absorption, particulate matter (PM10) adsorption and shade effect using a GIS opensource app (QFIELD and QGIS). Bio-morphometric parameters (diameter at breast heigh, tree height, first branch height, crown width according to the cardinal points, crown shape and density, tree defects as cavities, decays, severity of pruning, etc.) were recorded in situ during spring and summer. An integrated urban tree inventory was built including both quantitative and qualitative information and the integration between the three software (ITREE, QGIS, QFIELD) has allowed us to observe the precise and punctual geographical context.
From the paper file we have moved on to a computerized file linked to the geographical point and this allows us to link the observed defects and the calculated benefits of the trees to their position (proximity to buildings, presence of agricultural spaces). Hackberry (Celtis australis L.) is a broadleaf tree species, has a fast growth rate, little leaves and an height at maturity of 20 meters. The total number of hackberry tree was 321 (179 on the right and 142 on the left in direction of Pontedera). Their main hazardous defects depend on severe pruning and on conditions of the rooting site, but overall the most abundant failure risk classes are B (low) with 155 plants and C (moderate) with 136 trees. Only one is “D” class (extreme failure risk). These trees contribute to reduce summer air conditioning loads by shading buildings and, if tree canopy is sufficient, lowering air temperatures. In our case total electricity saved was equal to 40 GJ for a value of about 2240 Euros. Annual carbon dioxide reductions and releases amount to 178,600 kg/year (total stored CO2) and to 13,440 kg sequestered (value total net CO2 about 110 Euros). Trees decrease also air pollution by adsorbing fine dust quantified in 270 kg deposition of pollutants.
The awareness of the existence of these benefits and their ecosystem and socio-economic value represents a starting point for improving the green urban ‘capital’ and the management practices to optimize their benefits. This integrated approach is an information and governance opportunity to create a widespread consciousness of the value of urban green assets and implementing concrete actions to maximize their functions against the impact of climate change and air pollution.
Currently, the possibility of an Open Source and a pocket GIS platform, such as QFIELD, truly represents a unique opportunity to make the work easier, faster and more accurate. At the same time, the GIS allows us to have a continuous overview of the data produced on site and to further implement information regarding the investigation by using geospatial analysis, which helps to facilitate the final interpretative.
Sometimes trees were prematurely removed, not replaced, and inadequately maintained because controlling costs outweighs management aimed at increasing their health and the ecosystem services they provide over the long term. The informatic tree census allowed us to give a fairly broad picture of the benefits of trees of this very busy road. Considering the empty places (removals) and the stumps still present, the system will be able to simulate the increase in benefits once the trees will be reintegrated.
In conclusion this study could be used by the Municipality for the redevelopment of the tree-lined road and to improve the quality of life of the residents, mitigating the effects of pollution.