Combined inhibition of VEGF/VEGFR2 and Ang/Tie2 pathways provided efficient therapy for ovarian cancer in mice. In addition, antiangiogenic gene therapy has potential as a treatment for the accumulation of ascites.
<p>As cities are taking actions to reduce and offset part of their anthropogenic carbon dioxide (CO<sub>2</sub>) emissions, urban vegetation has become vitally important in pursuing carbon neutrality and climate mitigation. Its effectiveness in carbon sequestration, however, has large uncertainties due to the complex urban environment comprising both natural and artificial elements. By considering seven interacting land surface covers (buildings, pavement, evergreen trees, deciduous trees, grass, soil and water) within each model grid, the Surface Urban Energy and Water balance Scheme (SUEWS) is an urban land surface model that can simulate energy, water and CO<sub>2 </sub>exchanges in cities. For SUEWS to simulate the CO<sub>2</sub> fluxes in urban green spaces, it requires information of maximum photosynthesis and surface conductance of specific urban vegetation as well as the response of surface conductance to environmental conditions. To derive these parameters, it is necessary to utilize on-site measurements conducted over urban green spaces for an accurate description of the surface processes and variables.</p> <p>To our knowledge, only the mixed vegetation type and street trees in Helsinki have been parameterized in SUEWS so far. In order to extend the flexibility and usability of SUEWS modelling across different cities and for specific urban vegetation, this research aims to (1) derive surface conductance and photosynthesis parameters from eddy covariance and chamber measurements conducted over several urban sites corresponding to different urban vegetation types, such as non-irrigated lawn, turf grass, park trees, urban fields, green roof and urban forests (evergreen and mixed-leaf); and (2) evaluate the impact of selected surface conductance and photosynthesis parameters on SUEWS model performance in two mid-latitude cities: Swindon, UK and Minneapolis-Saint Paul, USA.</p> <p>The surface conductance and photosynthesis parameters for specific urban vegetation are derived by fitting measurements to an empirical canopy-level photosynthesis model where the effect of the local conditions (i.e. meteorology and ecology) is considered. Using the bootstrapping method to randomly select seven-eighths of the available measurements for 100 times, the fitted maximum photosynthesis rates range from 5.27 &#956;mol m-2 s-1 over an non-irrigated lawn to 10.72 &#956;mol m-2 s-1 over an evergreen forest with the dependencies on the local environmental response functions such as air temperature, incoming shortwave radiation, specific humidity deficit and soil moisture deficit. As a following step, the choice of model parameters in SUEWS simulations will be examined in the two cities along with on-site measurements.&#160;</p> <p>This research improves SUEWS simulations over urban areas by deriving new surface conductance and photosynthesis parameters specific to different urban vegetation types and provides a more accurate quantification of their biogenic CO<sub>2</sub> flux in a complex urban environment. The results also provide a better understanding on the carbon sequestration potential of urban vegetation, which will be useful in planning urban green spaces to maximize natural carbon sinks and in setting climate mitigation strategies.</p>
Abstract. Urban vegetation plays an important role in offsetting urban CO2 emissions and mitigating heat through tree transpiration and shading. With frequent heatwave events and the accompanying drought, the functioning of urban trees is severely affected in terms of photosynthesis and transpiration rate. The detailed response is however still unknown despite tree functioning having crucial effects on the ecosystem services they provide. We conducted sap flux density (Js) and leaf gas exchange measurements of trees (Tilia cordata, Tilia × europaea, Betula pendula, Malus spp.) located at four types of urban green areas (Park, Street, Forest, Orchard) in Helsinki, Finland, over two contrasting summers 2020 and 2021. Summer 2021 had a strong heatwave and drought, whereas summer 2020 was more typical for Helsinki. In this study, our aim was to understand the responses of urban tree transpiration and leaf gas exchange to heatwave and drought and examine the main environmental drivers controlling the transpiration rate during these periods in urban green areas. We observed varying responses of tree water use during the heatwave period at the four urban sites. Js was found to be 35–67 % higher during the heatwave as compared to the non-heatwave period at the Park, Forest, and Orchard sites but no significant difference was found at the Street site. Our results showed that Js was higher (31–63 %) at all sites during drought as compared to non-dry periods. The higher Js during the heatwave and dry periods were mainly driven by the high atmospheric demand for evapotranspiration represented by the vapor pressure deficit (VPD), suggesting that the trees were not experiencing severe enough heat or drought stress that stomatal control would have decreased transpiration. Accordingly, maximum assimilation (Amax), stomatal conductance (gs), and transpiration (E) at the leaf level did not change at the four sites during heatwave and drought periods. However, gs was substantially reduced during the drought period at the Park site. VPD explained 55–69 % variations in the daily mean Js during heatwave and drought periods at all sites except at the Forest site where the saturation of Js at high VPD was evident due to low soil water availability. The heat and drought conditions were untypically harsh for the region but not excessive enough to restrict stomatal control and the increased transpiration indicating that ecosystem services such as cooling was not at risk.
<p>Urban green areas have multiple benefits extending from heat mitigation and carbon sinks to human well-being. Due to their multi-benefits, they are an attractive natural solution to aid climate change adaptation and mitigation. In cities of Helsinki and Tampere located in Finland, intensive observations and modelling of urban water and carbon dioxide (CO<sub>2</sub>) fluxes have taken place to improve our understanding of the functioning and carbon sequestration potential of different urban green areas and provide science-based evidence for decision-makers on how urban green areas should be planned and constructed to maximize their climate benefits.</p> <p>Extensive eco-physiological observations were collected from different vegetation types (urban forest, park, garden, and street vegetation) in Helsinki during summers 2020-2022. The observations were made in the vicinity of the ICOS Associated Ecosystem Station FI-Kmp where eddy covariance (EC) measurements presenting the ecosystem level are conducted. The measurements included photosynthesis, sap flow, soil respiration, phenology, fine root growth, meteorology and soil properties. FI-Kmp represents mixed land use and vegetation, and to get more information of the behavior of lawns, additional EC measurements were conducted over urban lawn in the city of Espoo in 2021-2022. The observations are complemented by ecosystem modelling using SUEWS (Surface Urban Energy and Water balance Scheme). SUEWS is used to examine the impact of different urban green area planning options on carbon sinks and storages with focus on the city of Tampere.&#160;</p> <p>This work will highlight some of the findings made so far and provide examples on the carbon and water fluxes in different urban green areas. We also demonstrate how science-based knowledge can aid decision-making concerning urban green areas.</p>
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