NATURAL REGENeRATION IN KEKILLA FERNLANDS IN THE PERIPHERY OF SINHARAJA WORLD HERITAGE SITE

Abstract

In tropical moist climate Dicranopteris !inearis (Kekilla) fernland can develop as a resultof rain forest clearance followed by frequent burning. In Sri Lanka D. linearis fernlandsare capable of suppressing the natural regeneration of rain forest. Sinha raja WorldHeritage Site is one of the least disturbed and biologically unique lowland rain forest nowremaining in Sri Lanka. Some areas of the periphery of Sinharaja are covered with Dlenearis fern. Natural regeneration dynamics of soil seed banks need to be studied as apossible source of regeneration for forest restoration in these fern lands.

This study was carried out to understand the natural regeneration of soil seed bank inKekilla fernland with reference to surface soil disturbance and trophographic levels in theperiphery of Sinharaja World Heritage Site.

Three sites of Kekilla fernlands were selected for the study. Two surface soil disturbancetreatments were applied to each site. The first treatment (Root Removal) was applied at thebeginning of the study. The next treatment (Till) was applied to each site after six monthsfrom the first treatment. Seeds in the soil were allowed to germinate and seedlings werecounted once in two weeks during the first four months. After four months the seedlingswere recorded once a month. Transectswere laid out in each site to understand the floristiccomposition in surrounding vegetation of D. lenearis fernlands.

Seedlings of 35 taxa were identified during the period of study. The study revealed thatboth soil disturbance treatments can facilitate the establishment of herbs, shrubs and treesin the fern land dominated by D. lenearis. Results showed that herbs, shrubs, grassesrepresented the greater proportions of seedling recruitment than pioneer trees. Seedlings ofprimary forest species were not existent

Species composition of soil seed bank ill three-tophographic positions was not significantlydifferent. Numbers of species and seedling density were greatest in root removal treatment.Seedlings of primary forest species found in surrounding vegetation were not regeneratingin the plots studied. Only few pioneer tree seedlings were found in the plots, representingsurrounding vegetation of Kekilla fernland.