A wind tunnel study of the airflow field and shelter efficiency of mixed windbreaks

Abstract Windbreaks have been widely used in northern China and many other arid and semiarid areas in the world to reduce wind speed, wind erosion and counter sand dune encroachment. Although there has been a considerable number of studies examining the changes of airflow and the shelter efficiencies for windbreaks composed of different plant types, more in-depth studies are still needed to investigate the case of mixed windbreaks. Here, we used model plants to establish two representative plant architectures, namely the inter-plant and inter-row, and to measure the airflow speed by means of wind tunnel experiments. Results of our study show that there are a number of distinct airflow regions, including an acceleration region above the canopy, a large deceleration region within the canopy and leeward of the windbreaks, and a local acceleration region below the canopy of first few rows. These airflow regions were independent of windbreak plant architecture. The inter-row architecture of windbreaks, however, showed a stronger wind reduction inside the windbreak as well as on the leeside than that of the inter-plant architecture. The highest wind reduction ratios occurred at the canopy leeside edge, which was around 60% for the inter-plant windbreak and over 80% for the inter-row windbreak. These results provided strong evidence that the inter-row windbreak plant architecture should be favored to decrease wind speed and counter wind erosion in the arid northern China and similar regions globally.