Browsing by Subject "HEAT-ISLAND"

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  • Zsebeházi, Gabriella; Mahó, Sándor István (2021)
    Land surface models with detailed urban parameterization schemes provide adequate tools to estimate the impact of climate change in cities, because they rely on the results of the regional climate model, while operating on km scale at low cost. In this paper, the SURFEX land surface model driven by the evaluation and control runs of ALADIN-Climate regional climate model is validated over Budapest from the aspect of urban impact on temperature. First, surface temperature of SURFEX with forcings from ERA-Interim driven ALADIN-Climate was compared against the MODIS land surface temperature for a 3-year period. Second, the impact of the ARPEGE global climate model driven ALADIN-Climate was assessed on the 2 m temperature of SURFEX and was validated against measurements of a suburban station for 30 years. The spatial extent of surface urban heat island (SUHI) is exaggerated in SURFEX from spring to autumn, because the urbanized gridcells are generally warmer than their rural vicinity, while the observed SUHI extent is more variable. The model reasonably simulates the seasonal means and diurnal cycle of the 2 m temperature in the suburban gridpoint, except summer when strong positive bias occurs. However, comparing the two experiments from the aspect of nocturnal UHI, only minor differences arose. The thorough validation underpins the applicability of SURFEX driven by ALADIN-Climate for future urban climate projections.
  • Marttinen, Eeva M.; Niemi-Kapee, Juhamatti; Laaka-Lindberg, Sanna; Valkonen, Jari P. T. (2020)
    Green roofs play an important role for cities in mediating some problems caused by urbanization. Mosses are ecologically important plants and capable of tolerating harsh conditions, and thus their use for greening building surfaces has become more common. There is only a little information concerning moss-associated microbes, especially those found in green roof environments. Moss-associated microbes might have significant role on the welfare of green roofs as they might induce both beneficial as well as adverse effects on mosses. In this study, the occurrence of fungal populations was studied on green roofs in Finland. A total of 94 samples were collected from nine different green roofs, and 64 fungal isolates and one oomycete were obtained from the brown, necrotic parts of the collected green roof mosses. The most general isolated fungal genus was Trichoderma, comprising 25 different fungal isolates. The second most common genus was Fusarium, with 15 fungal isolates. The third most common genus was Mucor, with nine fungal isolates. Most of the Trichoderma isolates were described as T. harzianum, whereas most of the Fusarium isolates were described as F. acuminatium. In addition, the genera Phoma and Mortierella were frequently present. Fifty-two of 65 isolates caused symptoms in the model plant Physcomitrella patens. The most harmful Trichoderma isolates were described as T. atroviride, T. viride, T. koningiopsis and T. hamatum, all of which caused severe damage to the protonema, stem and leaves. The most harmful Fusarium isolates were F. acuminatium, F. avenaceum and F. tricinctum. The genera Mucor and Mortierella were isolated but they did not cause detectable symptoms in P. patens. These results indicate that many fungal isolates belonging to different genera are able to colonize mosses on green roofs and some of them cause severe damage to the mosses.
  • van Dijk, Laura J. A.; Moreira, Xoaquin; Barr, Anna E.; Abdala-Roberts, Luis; Castagneyrol, Bastien; Faticov, Maria; Hardwick, Bess; ten Hoopen, Jan P. J. G.; de la Mata, Raul; Pires, Ricardo Matheus; Roslin, Tomas; Schigel, Dmitry S.; Timmermans, Bart G. H.; Tack, Ayco J. M. (2022)
    The world is rapidly urbanizing, thereby transforming natural landscapes and changing the abundance and distribution of organisms. However, insights into the effects of urbanization on species interactions, and plant-pathogen interactions in particular, are lacking. We investigated the effects of urbanization on powdery mildew infection on Quercus robur at continental and within-city scales. At the continental scale, we compared infection levels between urban and rural areas of different-sized cities in Europe, and investigated whether plant traits, climatic variables and CO2 emissions mediated the effect of urbanization on infection levels. Within one large city (Stockholm, Sweden), we further explored whether local habitat features and spatial connectivity influenced infection levels during multiple years. At the continental scale, infection severity was consistently higher on trees in urban than rural areas, with some indication that temperature mediated this effect. Within Stockholm city, temperature had no effect, while local accumulation of leaf litter negatively affected powdery mildew incidence in one out of three years, and more connected trees had lower infection levels. This study is the first to describe the effects of urbanization on plant-pathogen interactions both within and among cities, and to uncover the potential mechanisms behind the observed patterns at each scale.