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1 Boczoń A.

1 2002

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Zastosowanie metody impulsu cieplnego do pomiaru prędkości przepływu wody w pniu dębu

Boczoń A.

Czasopismo Techniczne. Środowisko

2002

R. 99, z. 5-Ś

73--84

There are many methods direct and indirect that make possible to measure the water consumption in plants. In the case big trees, the use of many of those methods is not possible or measurements are imprecise. Big sizes attained by trees prevent in practice from the use of lysimetric methods. Instead of them, methods consisting in measurements of the velocity of water flowing through the tree trunk are gaining still greater significance, considering the fact that the throughflow ways are the most concentrated just in the trunk. Such location of measurements is favorable also for the fact that the trunk is the place where all amount of water taken out by the root system passes, and also the fact that trunk has a compact structure that is easy to be measured. The methods using the heat impulse are at present the most important group of methods measuring the velocity of water flowing through the trunk. The beginning of their development falls on the thirties of the 20th century. The first attempts consisted in introducing heat to trunk and in measuring the time during which the heat passed over a definite distance (the classic method). The development of technique, electronics, and miniaturization ofequipment led to formation of many methods using heat impulse. The TDP (Thermal Dissipation Probe) method is one of the methods mentionewd above. There the speed of throughflowing water is determined from the difference of temperatures between two sensors. The report presents the sue of the method for determination of the speed of water flowing through a 300-year-old pedunculate oak growing in the Białowieża National Park, on the moist broadleaved forest site. The measurements carried out showed a daily and seasonal variability, and an impact of meteorological conditions on the amount of water uptake by the tree under study. At the beginning and at the end of the vegetation season the velocity of the water throughflow was linked with the foliage development degree. In the period when the tree had maximum foliage, the velocity of water throughflow depended on meteorological conditions. At night the velocity was near zero, but during the day it was over 13cm x h-1. It was observed that at cloudy days the throughflow velocity was lesser than at sunny days. Precipitation was the factor that strongly refrained the velocity of water flowing through the tree.