investigate tress growth situation Wood core extractor: d=5mm Drill pipe length: 20cm, 25cm, 30cm, 35cm, 40cm ... reach the center, make a reverse rotation, and get wood core within core extractor. Tree growth condition can be analysed by watching ... wood core color distribution.CompositionSleeve, awl and a core extractorModelWood core extractor: d=5mmDrill pipe length: 20cm ...