Trees near construction sites and roads are exposed to an increased risk of stem injuries, and urban trees are also vulnerable to vandalism. Such injuries can result in large wounds, leading to reduced water and nutrient transport, taking several years to occlude, and the apparent risk of decay. Covering the wounds with plastic wrapping has been discussed over the years, but the evidence for its efficacy is not complete. During winter 2020/2021 a total of 248 trees were systematically vandalised in Malmö, Sweden. The two organisations responsible for these trees handled the injuries differently; one wrapped the stem wounds with plastic, and the other did not. This provided a rare opportunity to compare the treatment outcomes in urban field conditions.

We studied the effects of plastic wrapping on tree wounds by comparing data from measurements that were performed in 2021 with measurements in 2023. The study focused on 3 genera: maple (Acer), birch (Betula), and linden (Tilia).

Tree wounds in both linden and maple wrapped in plastic occluded faster than unwrapped trees, but no benefit of wrapping could be seen in birch. There was an overall difference of occlusion rate between the genera, where the linden trees wrapped in plastic occluded faster than the wrapped trees of maple and birch.

Plastic-wrapping can benefit urban trees with stem wounds. However, the effect is at least genera, if not species, specific. This highlights the need for further studies of differences across different genera and species.

Spectral analysis of data acquired using ground penetrating radar (GPR) allows for the evaluation of the amplitudes and frequencies associated with reflections generated by subsurface materials and their interaction with electromagnetic waves. This interaction produces a unique response for each material type.

In this study, we tested two widely used time-frequency tools (the short-time Fourier transform [STFT] and power spectral density [PSD]) to characterize the subsurface roots of three distinct tree species: Jacaranda mimosifolia, Libidibia ferrea, and Handroanthus impetiginosus. Furthermore, we developed an artificial neural network (ANN) to distinguish the evaluated species, complementing the spectral analysis. GPR data were collected using a 900 MHz antenna within an area containing all 3 species.

Through spectral and ANN analysis of 200 A-scans (single radar traces) per species, we were able to differentiate them in the frequency domain, demonstrating the potential of signal processing techniques for mapping tree roots. Validation was achieved through excavation of the site around L. ferrea (which was suppressed), enabling the accurate identification of each root encountered.

Using spectral analysis and ANN, it was possible to differentiate the root system of the 3 species evaluated using GPR data.