Relation between the level of degradation and the wind speed reduction efficiency of tree windbreaks systems in Ovche Pole region, Macedonia

Abstract

Ovche Pole is an agricultural region in Macedonia with dry climatic conditions characterized by low precipitation and high ambient temperatures during the growing period as well as prevailing winds that are present considerable time of the year. During the 1950s series of measures have been implemented to improve the agriculture productivity in the region. One of the measures taken was the establishment of tree windbreaks (field shelterbelts) aimed to reduce wind velocity and protect shelter crops. Ever since they become essential elements for the regional landscape, performing many important ecosystem functions. As far as authors' knowledge, so far there are no scientific studies that investigated the performance of the tree windbreaks in Ovche Pole-research area of this study. To fill the gap of scientific data, this study examines the relation between wind reduction efficiency of tree windbreaks with their level of degradation in that area. Optical porosity is used as a proxy for quantitative description of the level of degradation of the structure of the tree windbreaks. To this aim, field measurements for wind velocity and optical porosity (OP) were done on 3 (three) windbreaks sections. Photogrammetry method was used to determent the porosity at each windbreak section. Wind velocity field measurements were done with two handheld cone anemometers The windspeed reduction efficiency was assessed by comparing the windspeed at the windward side with the windspeed at 3 points on the leeward side. The results show that the level of degradation is significantly related with the relative windspeed at distance of 30m and 60m from the tree line at the leeward side.