Trees bring many benefits to the urban environment. However, they may also cause hazards to human population, being the major causes of injuries and infrastructural damage during strong wind events. In the city of Lisbon, strong winds rather frequently result in tree falls, depending on the season and meteorological conditions. This paper presents a methodology to analyse tree damage due to strong wind events in urban environments. Each occurrence has been recorded by the Lisbon Fire Brigade and Rescue Services (Regimento de Sapadores Bombeiros de Lisboa -RSBL). Information provided by RSBL relating to the period of 1990-2005 was considered along with hourly wind speed and direction, species, fitossanitary conditions and urban parameters. To ensure that the fallen trees were caused by strong winds, only days with three or more occurrences of fallen trees were selected. It was found that in summer, northerly winds are responsible for 11% of tree falls, with winds from other directions (west, southwest and south) responsible for 5%. From autumn to spring, perturbed weather conditions originating from the west, southwest and south are responsible for 84% of fallen trees. The majority of tree falls occurred when wind speed surpassed 7 m/s in the six hours prior to their fall. Some recommendations to the Civil Protection Agency and the Fire Department are presented to improve the mission of collecting information. This research is a contribution to the assessment of wind risk in Lisbon.A. Lopes et al. Střelcová, K., Škvarenina, J. & Blaženec, M. (eds.):

Leaf area indexMomentum roughness length Remote sensing Surface energy balance Surface temperature METRIC™ is a satellite-based surface energy balance model aimed at estimating and mapping crop evapotranspiration (ET). It has been applied to a large range of vegetation types, mostly annual crops. When applied to anisotropic woody canopies, such as olive orchards, extensions are required to algorithms for estimating the leaf area index (LAI), surface temperature, and momentum roughness length (Z om ). The computation of the radiometric surface temperature needs to consider a three-source condition, thus differentiating the temperature of the canopy (T c ), of the shaded ground surface (T shadow ), and of the sunlit ground surface (T sunlit ). The estimation of the Z om for tall and incomplete cover is based upon the LAI and crop height using the Perrier equation. The LAI, Z om , and temperature derived from METRIC after these adjustments were tested against field collected data with good results. The application of METRIC to a two year set of Landsat images to estimate ET of a super-intensive olive orchard in Southern Portugal produced good ET estimates that compared well with ground-based ET. The analysis of METRIC performance showed a quantitative improvement of ET estimates when applying the three-source condition for temperature estimation, as well as the Z om computation with the Perrier equation. Results show that METRIC can be used operationally to estimate and mapping ET of super-intensive olive orchards aiming at improving irrigation water use and management. ScienceDirect journal homepa ge: www .e lsev ie r.com/locate/issn/153 75110 b i o s y s t e m s e n g i n e e r i n g x x x ( 2 0 1 4 ) 1 e1 3Please cite this article in press as: Pôç as, I., et al., Satellite-based evapotranspiration of a super-intensive olive orchard: Application of METRIC algorithms, Biosystems Engineering (2014), http://dx.

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SUMMARYThe removal of the litter layer in Portuguese pine forests would reduce fire hazard, but on the other hand this practice would influence the thermal regime of the soil, hence affecting soil biological activity, litter decomposition and nutrient dynamics. Temperature profiles of a sandy soil (Haplic Podzol) under a pine forest were measured with thermocouples at depths to 16 cm, with and without litter layer. The litter layer acted as a thermal insulator, reducing the amplitude of the periodic temperature variation in the mineral soil underneath and increasing damping depths, particularly at low soil water contents. At the mineral soil surface the reduction of amplitudes was about 2.5 ºC in the annual cycle and 5 to 6.7 ºC in the daily cycle, depending on the soil water content. When soil was both cold and wet, mean daily soil temperatures were higher (about 1 -1.5 ºC) under the litter layer. Improved soil thermal conditions under the litter layer recommend its retention as a forest management practice to follow in general.Index terms: soil temperature, Fourier series, damping depth.(1) Received for publication in May 2010 and approved in July 2010.