Recovery of Lichen Diversity During Forest Restoration in Northern Thailand

ABSTRACT: This study investigated the recovery of lichen diversity during restoration of upland evergreen forest in northern Thailand. Lichen diversity and species frequencies were recorded within experimental plots, planted by the Forest Restoration Research Unit (FORRU) in the years 1998, 2000 and 2002 (8, 6 and 4 years since planting) near Ban Mae Sa Mai in Doi Suthep-Pui National Park. Lichen floras in these plots were compared with those of natural forest (Dong Seng forest on Doi Mea Sa). The objectives of the study were to observe the recovery of lichen communities on trees of different ages in the reforestation plots and to provide baseline information on lichen species as bioindicators for forest recovery in Northern Thailand. Four framework tree species; Hovenia dulcis Thunb, Melia toosendan Sieb & Zucc, Prunus cerasoides D. Don and Spondias axillaris Roxb were chosen and lichens on their tree trunks were collected. Lichen data were recorded using a commercial frame 20 centimeter wide, subdivided in smaller squares of 2.5 x 2.5 cm. The frame was wrapped horizontally around each tree’s girth, 1 meter above ground level.

Forest restoration, using the framework species method, resulted in a 57% recovery of the lichen flora (plot 1998 compared with natural forest) within 8 years following tree planting (by Sorensen’s similarity index); Buellia sp.1, Diorygma cf. epiglaucum, Dirinaria confluens, Graphis sp.2, Graphis sp.4, Graphis sp.5, Graphis sp.9, Graphis sp.10, Graphis sp.11, Graphis sp.13, Haematomma puniceum, Lecanora sp.1, Lecanora sp.5, Malcolmiella sp.5, Malcolmiella sp.2, Malcolmiella sp.7, Pertusaria sp.1, Porina sp.1. Recovery of lichen diversity increased in plots with longer reforestation age. Some of the lichen species considered as indicators for forest recovery in this study were: Graphis sp.9, Haematomma puniceum, Malcolmiella sp.2 and Hypotrachyna sp.1.

A total of 795 epiphytic lichen samples were collected. The samples were divided into two main types: foliose and crustose and they represented 6 orders, 14 families, 31 genera and 70 species. The highest lichen diversity (by Shannon’s diversity index) was found on P. cerasoides (2.80) in Dong Seng Forest, whereas the lowest value (0.25) was on M. toosendan in plot 2002. Some crustose lichen genera, such as Chrysothrix, tended to be pioneers, whereas foliose lichen genera, such as Bulbothrix, occurred more in the older plots and in natural forest.

Sorensen’s similarity index showed that the lichen communities on all selected tree species were most similar between plots 1998 and 2000 (0.69 or 69%). The least similar plots were plot 2002 and Dong Seng forest (0.23 or 23%). Within plot 1998, lichen communities on H. dulcis and S. axillaris were most similar (0.85 or 85%). Lichen communities on H. dulcis in plot 2000 and P. cerasoides in plot 2002 were least similar (0.13 or 13%). Light intensity and air temperature in plot 1998 and Dong Seng were not significantly different. In plots 2000 and 2002, these parameters were not significantly different (p<0.05). Relative air humidity, among all sites, did not differ significantly (p<0.05). Correlation between lichen communities and environmental factors were analyzed by Principal Coordinate Analysis (PCA) and Detrended Correspondence Analysis (DCA), using the Multivariate Statistical Package (MVSP3.1) program. Environment factors such as temperature, light intensity, pH of bark, and elevation above sea level, influenced the distribution and diversity of lichens.