Characteristics of acoustic emission wave parameter of xylem cavitation in Pinus tabulaeformis

In the paper, we aim to provide a quantitative description of characteristics of the cavitation xylem occurrence, development and restore characteristics of Pinus tabulaeformis (Chinese pine). The controlling mechanisms of water consumption in Chinese pine of xylem conduits cavitation and embolism had been studied.The acoustic emission (AE) method had been adapted to check and measure the wave parameter of acoustics emission from xylem conduits cavitation. Its acoustic emission signal had been studied systematically by acoustic emission instruments detected, recorded and analyzed. The results indicated that the xylem cavitation and embolism occurred frequently and paroxysmal in the tree body.Its acoustic emission signal frequency in the spectrum ranged from 230 to 270 kHz; acoustic signals on time sequence, the daily signals variation characteristics were sending at the peak from 06:00 to 17:00. The period from 18:00 to the next day 06:00 was low signal period. Concerning the singal seasonal changing characteristics, the singal number was more and higher in June,August and October than that in December. For spatial distribution in tree body organization, the singal was dense in tree trunk and branches of the upper part (near the treetops), while there was little and sparse signal in the middle and lower part of the tree. For signal arrival time, the branches generally received the signal first and there was 1 to 20 min earlier than that to tree trunk, while there was no visible difference in trunk part.The night detected signals of tree body were the sound of catheter cavitation or a column of water produced when it backfilled trees in the natural growth environment. Its hole turn catheter (tracheids) can rely on its own moisture transmission mechanism to repair itself properly.The acoustic emission wave of xylem cavitation is the water carryforward signal of tree bodies. The xylem embolism resulted in cavitation. Ultrasonic acoustic emissions methods could be used for measuring the signal, according to the result, the necessary water politic for trees would be carried out. The characteristic of water capacitance indicate that the tissues of the trees have the capability to hold water. So the trees could suffer from a considerable degree of watershorting conditions.