Browsing by Author "Ruud, Carl"

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HEAT TOLERANCE AND HEAT ACCLIMATION IN POTENTIAL FUTURE URBAN TREE SPECIES IN SWEDEN
(2025-06-24) Ruud, Carl; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
The full effect on urban greenery due to global warming and future increased intensity and frequency of heatwaves is still unclear. Harsh urban conditions, like the urban heat island effect, may require the introduction of new tree species to maintain urban greenery. This study investigated the heat tolerance of five tree species not endemic to Sweden (Koelreuteria paniculata, Liquidambar styraciflua, Liriodendron tulipifera, Magnolia kobus, and Nyssa sylvatica). The research questions were: (1) Will the trees see an increased stress level with increased leaf temperatures? (2) Will the trees acclimate and become more stress-resilient after exposure to heat waves?, and (3) How does the ability to acclimate to heat stress vary among species? During the experiment, trees were exposed to three heat waves. Control treatments were exposed to 23°C in the first two heatwaves, while heat-treated trees were exposed to 33°C. In the third heatwave, both control and heat-treated trees were exposed to 38°C. To evaluate the heat stress tolerance, measurements for net photosynthesis, stomatal conductance, and photosystem II functionality (evaluated as the temperature at which the functionality was reduced 50% of unstressed values, T50) were taken after each heatwave. Additional leaf measurements of leaf temperatures, angles, light intake, and size were also taken for each heatwave. The results show a mixed response between species, indicating species-specific ability to handle heat. No significant results were found to show that trees exposed to multiple heat waves acclimate to become more heat stress resilient. However, trees exposed to repeated heat waves had fewer cases where leaf temperatures exceeded their T50 temperatures. Koelreuteria paniculata stood out as the previously heatwave-exposed individuals managed to maintain higher stomatal conductance and net photosynthesis in heatwave 3, compared to individuals exposed to a single strong heatwave. Another finding was the steady decline of Liriodendron tulipifera throughout the heat waves, as the heat-treated individuals significantly decreased in T50, stomatal conductance, and net photosynthesis over the three heat waves. As a whole, the results indicate that the five tree species may be able to handle moderate heat stress (33°C), but that severe heat stress (38°C) may be too much for them to handle. This suggests that the studied species may not be suitable for planting in the most heat-exposed urban locations.
TRANSPORTEFFEKTIVITET AV SCHAKTMASSOR OCH DESS MILJÖPÅVERKAN
(2023-06-27) Ruud, Carl; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
Society is aiming to move towards higher sustainability. To achieve the climategoals for future sustainability we need to lower our carbon emissions in every area possible. The transportation of excavation masses with trucks is hard to avoid since it is not easily replaced. However, transportation can be conducted more efficiently to decrease the negative impacts. This study aims to analyze the transport efficiency between different types of excavation masses and estimate the economic loss and unnecessary carbon emissions an ineffective usage of diesel fuel is responsible for. The study also investigates to what degree the visualization of the degree of filling for drivers and contractors of trucks can improve transport effectiveness over the duration of a specific ongoing project. This is done by analyzing data, plotting simple graphs, and using a simple mathematical model in Excel with data provided by Pinpointer AB. The conclusion of the study was that there are significant differences in the transport efficiency of different excavation masses, especially concrete which showed very high average distances in its transportation. The estimated amount of ineffective diesel fuel usage is calculated to be 2452 liters. Visualization of the degree of filling did not show an increase in the degree of filling over the duration of a specific project, which indicates that the data have not been used in the intended way, to follow up and improve the degree of filling.