Terrestrial Fern Diversity in Urban Forest in DKI Jakarta

Abstract

Urban forest is an ecosystem consisted of plant vegetation community that resembles natural forest. Trees within the urban forest form canopy that construct well-suited environment for the understory life. One of the understory is fern. Fern is a vascular and intermediate plant that produces spores as its main characteristic. This research was intended to compare the diversity of fern under three urban forests in DKI Jakarta region which were the urban forest University of Indonesia (UI), Arboretum Cibubur, and urban forest PT Jakarta Industrial Estate Pulogadung (PT JIEP) Pulogadung. The research was started in November 2011 until March 2012. Vegetation analysis was made by doing purposive sampling with square method. Fern and non-fern specimens were collected for herbarium purpose then were identified based on identification book. Light intensity, temperature, humidity, soil pH were measured and recorded as supported data. The other environment factors that measured were physical and chemical structures of soil and also the quality of the air. The coverage data and the frequency of each species were used to count the importance value index (INP). Sharon Diversity Index (H'), Evenness Index (E), and Sorenson Similarity Index (IS) were also counted in. There were epiphytes fern (4 species) and terrestrial fern (18 species) in the research urban forest. The ferns have herb habit, but they varied in the growth types which are erect; creeping and climbing. Fern leaves have variation in size, shape of fertile and sterile leaves, shape of the first leaf and so on. Based on the leaf size, two kinds of leaf, microphyl and megaphyl, were found. Based on the different shape of fertile and sterile leaves, monomorphyc and dimorphic leaves were found. The shape of monomorphyc leaf varied which were simple, pinnatus and bi-pinnatus. Fern reproductive structure in urban forest varies in the sori shape, location and composition, such as 1) sporangium is located in the leaf tips, form organ so called as strobilus; 2) longitudinal grooved sori on the edge as though covering the edge; 3) sori is located along vascular leaf between costa and the edge of the leaf; 4) sori is rounded or oval spreaded on the vascular leaf with or without indusium; 5) sori is rounded or oval, located on the tips on the free vascular near the leaf edge; 6) sori on the fertile leaflet produces sporangia that spread from the edge of the leaf to the venation tips. Sporangia on two rows is covered by indusia. The sum of terrestrial ferns found in three research urban forests were 18 species belong to 8 familia and 11 genera. In UI urban forest, it was found 10 genera with 14 species; in Arboretum Cibubur, it was found 8 genera with 11 species; but there was no fern in PT JIEP urban forest. The number of all individual ferns found in three urban forest were 1030, consisted of 334 individual in Arboretum Cibubur urban forest and 696 in UI urban forest. The species diversity index (H' = 1.97) and evenness index (E = 0.82) in Arboretum Cibubur urban forest was higher than that of the UI urban forest (H' = 1.36 and E = 0.52) while similarity index (IS) between two urban forest was 0.56. The number of individual fern in UI urban forest was higher than that of Arboretum Cibubur urban forest. The dominant fern species in UI urban forest was Sphaerostephanos sp., but there is no dominant fern found in Arboretum Cibubur urban forest. From environmental point of view, PT JIEP urban forest has higher light intensity than the UI and Arboretum Cibubur urban forest, with dusty clay soil type. This type of soil has less aeration to reserve water. Except fern, vegetations in three urban forests are different in type and INP. In the UI urban forest, the plants with high INP were Adenanthera pavonina, Lagerstroemia speciosa and Clerodendron paniculata that grew fast to compose canopy. Therefore UI urban forest was more humid than Arboretum Cibubur urban forest. Vegetation in PT JIEP urban forest was not crowded, so there was open space dominated by Ruellia tuberosa, weeds in the open space. The result of CCA method indicated that environmental factor was related to the fern existence in the UI and Arboretum Cibubur urban forest. In UI urban forest, Pteris ensiformis lived in the open space while Microlepia sp. lived in the shelter. In Arboretum Cibubur, Dicranopteris linearis and Cristella subpubescens also lived in the open area and it did not affected by measured environmental factors while the other ferns still influenced by measured environmental factor.