การติดตามการเติบโตและอายุไขของไลเคน ณ อุทยานแห่งชาติเขาใหญ่ ประเทศไทย MONITORING GROWTH AND LIFE LONGEVITY OF LICHENS AT KHAO YAI NATIONAL PARK, THAILAND เวชศาสตร์ พลเยี่ยม, วาสนา เชื้อสุข และ กัณฑรีย์ บุญประกอบ

This study aimed at comparing growth and longevity of tropical lichens in six forests. Growth of tropical lichens is largely unknown. The information can be used as baseline data for conservation and sustainable utilization of lichen resources. Measuring expansions of 306 lichen thalli were performed during 1999-2005. Thallus growths were obtained by tracing their edges over transparent sheets at different time intervals. Growth rates were expressed as increasing thallus diameters per unit time. After 7 years, 57 % of the thalli disintegrated, mostly due to natural factors, only 132 thalli remained intact. Regardless of the lower montane forest, the highest rate of survival among the crustose thalli was found in the tree plantation (TP), and subsequently lower in the dry evergreen forest (DEF), the dry dipterocarp forest (DDF), the tropical rain forest (TRF) and the secondary forest (SF) accounted for 82, 71, 67, 49 and 44 % respectively. The foliose lichen had the highest survival rate in the DDF and lower in the TP, LMF, SF and DEF recorded 55, 33, 21, 18 and 13 % respectively. All of them in the TRF disintegrated. The remaining crustose thalli had average growth rate of 2.2 mm/year (n = 88), whilst 44 of the survival foliose thalli grew 5.2 mm/year. The highest growth rate of 8 mm/year was measured from the SF for the crustose lichens, and the 12.3 mm/year for the foliose lichens from the LMF. This investigation reveals that life longevity of the foliose lichens in the wet conditions of the TRF, DEF and SF seems to be shorter than those inhabited the dry site of the DDF, although growth rate of the former group was higher.