Insects Pollinators Communities In Distinct Habitats and Distances from Margin Forest of Gunung Halimun-Salak National Park

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1 DKSHE Insects Pollinators Communities In Distinct Habitats and Distances from Margin Forest of Gunung Halimun-Salak National Park By Reisky Maulana 1, Ani Mardiastuti 2, and Damayanti Buchori 3 Pollination service is one of many services that forest can provide INTRODUCTION especially for farming near to the forest, which definitely harbors a high biodiversity of pollinator insects. Yet, forest degradation by farming activities is a threat for pollinator insect diversity, so there must some awareness to be given especially for the villagers about how important their forest is for their farms. Observation on caisin s (Brassica rapa L.) flower-visitor insects were METHOD carried out over 20 days period from 28 December January 2007, in margin forest of Gunung Halimun-Salak National Park. All insect visiting the flowers were counted by using fixed sampling method within 30 minutes observation period in each site that consisted of 20 flowering caisin plants. The forest distance factor giving the best fit was shown in a simple linear regression model on scatter plot graphic. This study showed that 1312 insects are found in RESULT AND DISCUSSION caisin s flower but only 747 insects or 56,94% of them are the real pollinator which are representatives of 32 pollinator species within 15 observation sites along the margin forest. Highest diversity (H ) value of pollinator insects was found in habitat near to forest s margin habitat (H =1,84) than in other habitats at greater distances from forest. The abundances of pollinator insects were found high in open areas that provide less shade of trees. Species diversity and abundance of pollinator insects were CONCLUSION decreasing within distance from the forest despite there were many factors which may influence the abundance. The most influencing factor is the blossom coverage in observed sites that significantly has a positive correlation with flower visitation by insects. The other factors such as temperature and humidity did not significantly influence the flower visitation by insects. 1) Student of Forest Resources Conservation and Ecotourism Department, Faculty of Forestry IPB 2) Lecturer of Forest Resources Conservation and Ecotourism Department, Faculty of Forestry IPB 3) Lecturer of Plants Protection Department, Faculty of Agriculture IPB

2 RINGKASAN REISKY MAULANA. E Komunitas Serangga Penyerbuk pada Jarak dan Habitat yang Beragam dari Tepi Hutan Taman Nasional Halimun-Salak. Dibimbing oleh Prof. Dr. Ir. Ani Mardiastuti, M.Sc, dan Dr. Ir. Damayanti Buchori, M.Sc Penyerbukan tanaman pertanian yang dilakukan oleh serangga merupakan salah satu bagian dari jasa lingkungan yang diberikan oleh hutan karena hutan sebagai habitat alami diasumsikan menyimpan potensi keanekaragaman serangga penyerbuk yang tinggi. Namun aktivitas pertanian yang merusak hutan masih terus berlangsung, sehingga masyarakat petani yang tinggal di luar kawasan hutan perlu disadarkan akan manfaat hutan yang ternyata telah memberikan jasa penyerbukan bagi pertanian mereka. Penelitian ini bertujuan: (1) Mengidentifikasi dan mengelompokan fungsifungsi ekologis dari bermacam spesies serangga pengunjung bunga casin, (2) Menghitung jumlah spesies, kelimpahan, dan menilai indeks-indeks keragaman spesies serangga penyerbuk, (3) Menganalisa kemiripan struktur komunitas dan pola penyebaran serangga penyerbuk di tiap-tiap jarak yang berbeda dari tepi hutan, (4) Membuktikan besar-kecilnya pengaruh jarak dari tepi hutan terhadap jumlah, kelimpahan, dan indeks-indeks keragaman spesies serangga penyerbuk. Penelitian lapang dilakukan pada bulan Desember 2006 Januari 2007, berlokasi di pinggir kawasan hutan Taman Nasional Halimun-Salak, Dusun Pangguyangan, Desa Sirnarasa, Kabupaten Sukabumi, Provinsi Jawa Barat. Pengamatan serangga penyerbuk dilakukan dengan metode fixed sampling selama 30 menit tiap titik pengamatan yang telah ditanaman 20 tanaman caisin (Brassica rapa L.). Data yang didapat dianalisa dalam bentuk deskriptif dan kuantitatif. Pengaruh jarak hutan terhadap keragaman spesies serangga penyerbuk dinilai berdasarkan persamaan regresi dan grafik sebaran titik (scatterplots). Hasil penelitian selama 17 hari cerah di seluruh 15 titik pengamatan, menunjukan bahwa dari total kelimpahan 1312 ekor serangga pengunjung bunga casin hanya 747 ekor atau 56,94% yang merupakan serangga penyerbuk terdiri

3 dari 32 spesies. Kelimpahan serangga penyerbuk umumnya ditemukan lebih tinggi pada habitat yang terbuka atau tidak terhalang oleh tajuk pepohonan. Kelimpahan dan jumlah spesies tertinggi ditemukan pada titik pengamatan yang dekat dengan tepi hutan yang pada penelitian ini berupa kondisi habitat perladangan. Kelimpahan serangga penyerbuk semakin menurun seiring jaraknya yang semakin menjauhi tepi hutan, meskipun terdapat faktor-faktor lain yang dapat mempengaruhi tinggi-rendahnya kelimpahan serangga penyerbuk. Faktor tersebut ialah pengaruh jumlah pemekaran bunga caisin pada titik pengamatan yang berkorelasi positif dan berbeda nyata dengan kelimpahan serangga penyerbuk. Sedangkan faktor suhu dan kelembaban udara tidak menunjukan pengaruh yang berarti pada kelimpahan dan jumlah spesies serangga penyerbuk. Kata Kunci : Keanekaragaman spesies, serangga penyerbuk, metode fixed sample (Dafni 1992), bunga caisin (Brassica rapa L.), jarak dari tepi hutan.

4 SUMMARY REISKY MAULANA. E Insects Pollinators Communities In Distinct Habitats and Distances from Margin Forest of Gunung Halimun- Salak National Park. Under supervision of Prof. Dr. Ir. Ani Mardiastuti, M.Sc, and Dr. Ir. Damayanti Buchori, M.Sc. Pollination service is one of many services that forest can provide for farming near to the forest which definitely harbors a high biodiversity of pollinator insects. Yet, forest degradation by farming activities is a threat for pollinator insect diversity, so there must some awareness to be given especially for the villagers about how important their forest is for their farms. The objectives of this research are: (1) to identify caisin s (Brassica rapa L.) flower-visitor insects and to determine its function in its community, (2) to count abundance and species of pollinator insects and also to measure diversity index in distances from the forest, (3) to analyze spatial distribution of pollinator insects and its composition in every plot base on its similarity index, (4) to show the correlation of forest distance with the abundance and its diversity. Observation on caisin s flower-visitor insects were carried out over 20 days period from 28 December January 2007, in margin forest of Gunung Halimun-Salak National Park, Sirnarasa Village, District of Sukabumi, Province of West Java. All insect visiting the flowers were counted by using fixed sampling method within 30 minutes observation period in each site that consisted of 20 flowering caisin plants. The forest distance factor giving the best fit was shown in a simple linear regression model on scatter plot graphic. This study showed that 1312 insects are found in caisin s flower but only 747 insects or 56,94% of them are real pollinator insects which are representative of 32 pollinator species within 15 sites observation along the margin forest. Higher densities of pollinator insects are found near to forest s margin than at greater distances from forest. The abundances of pollinator insects are usually high in open areas that provide fewer shade trees.

5 Species diversity and abundance of pollinator insects were decreasing within distance from the forest despite there are many factors which may influence the abundance. The most influencing factor is the blossom cover of caisin in site observation that significantly has a positive correlation with flower visitation by insects. The other factors such as temperature and humidity did not significantly influence the flower visitation by insects. Key words: Species diversity, insect pollinator, fixed sampling method (Dafni 1992), caisin flower (Brassica rapa L.), forest in distances.

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