CHRONOBIOLOGY OF TREES: SYNTHESIS OF TRADITIONAL PHYTOPRACTICES
AND SCIENTIFIC RESEARCH, AS A TOOL OF FUTURE FORESTRY Ernst Zürcher, Chair of Wood Sciences, Department of Forest and Wood Sciences, Swiss Federal Institute of Technology Zurich, ETH Zentrum, HG F 21, CH-8092 Zürich, Switzerland. Presented at Third IUFRO Extension Working Party Symposium,
“Extension Forestry: Bridging the Gap Between Research and Application”, July 19-24, 1998, Blacksburg, Virginia, USA.
Empirical knowledge and traditions often mention a second level of influence, that of the
ascending and descending cycle of the moon, its tropical rhythm concerning the earth-moon relationship from a geocentric point of view (this second rhythm is less obvious to the observer). Indeed, the highest point, compared to the earth"s horizon, of each lunar passage varies systematically and in both directions. The moon"s trajectory takes it higher in the sky for 13 or 14 passages, then the tendency is reversed for the other half of the tropical month, which lasts for 27.32158 days. Here, the general rule is quite close to the previous one: "As the moon ascends, the sap rises faster in the upper part of plants and improves the quality of its constituents; . . . as the moon descends, the growth of plants above ground is slowed (Gabriel 198
. According to Wohlgenannt"s 1988 synthesis, the ascending moon brings a "separation from moisture and soil," whilst the descending moon "pulls all things downwards." First source of confusion: the ascending moon is sometimes confused with the waxing moon, the descending moon with the waning moon, despite a difference in periodicity of 2.21 days.