Floristic Composition of Home-garden Systems in Dumbara (Knuckles) Conservation Area with an emphasis on Endemic Species

Abstract

Home gardens are multistoried ecosystems and are important not only for in-situ biodiversityconservation, but also as valuable food sources, fodder, medicine and spices. The main objective ofthis study was to make decisions about the variations of home garden composition and to identify theendemic species. Fifty five home gardens were studied in northern flank from January to April 2012.Two large (10x10m2) and four small (1x1m2) quadrates were studied in each home garden. Individuals≥ 1.5 m height and ≥ 1 cm DBH were measured to calculate IVI. Species identification was done onsite and further at the National Herbarium, Peradeniya. Total of 1335 individual woody-perennials and4603 herbs were found in 11,000 m2 of study area. One hundred and fifty two woody-perennial species(19 endemic, 44 naturalized exotics, 37 cultivated and 52 timber) under 54 families and 56 herbspecies (46 medicinal) belonging to 33 families were recorded. Euphorbiaceae was the dominantfamily with 15 species, followed by Fabaceae (11 species), Anacardiaceae (10 species), Rutaceae (10species), Myrtaceae (7 species), Rubiaceae (6 species), Arecaceae (6 species), Moraceae (5 species),Sapindaceae (4 species) and Zingiberaceae (4 species). Highest number of plant families (43) wasrecorded in Pitawala, while the lowest number of plant families was recorded in Polommana (24).Based on the Importance Value Index (IVI), the species to pay highest priority for conservation wereselected. According to Shannon diversity values for different villages, Rathninda is the most stable andless disturbed, whereas Polommana is the most unstable and highly disturbed village. There were fiveendemic Anacardiaceae species (Campnosperma zeylanicum, Mangifera zeylanica, Semecarpuscoriaceae, Semecarpus nigro-viridis, Semecarpus walkeri). Twelve percent of the studied populationwere interested in timber trees such as Tectona grandis, Melia azedarach, Swietenia macrophylla andChloroxylon swietenia. Twelve percent of the studied population preferred fruit trees while 5% wereinterested in some medicinal plants. Preference of this nature indicates that in the future, the plantdiversity in these home gardens is likely to decline considerably. This might even lead to theextinction of rare, endemic plant species. Therefore, people in northern flank encouraged toincorporate multipurpose endemic plants and plants with less IVI values in their home gardens inorder to maintain high diversity and to conserve endemic and relatively rare plants while gainingsubstantial income through their home gardens.

Keywords: Northern Flank, Home gardens, Conservation, Woody-perennials, Endemic species