Keanekaragaman Arthropoda pada Ekosistem Hutan Pinus dan Hutan Eucalyptus di Aek Nauli Simalungun

Abstract

In the lake Toba Catchments Area the pine forest had been converted to Eucalyptus plantations, furthermore the single crop type was changed to other single crops plantation. Unfortunately the biodiversity change involved the ecosystem change. The possibility of the existence of the alteration of the diversity, abundance, and the composition of flora and fauna as the result of the conversion crop type, should be proved by a research. Research on the diversity of arthropod is one of biodiversity components in the two different ecosystems as the indicator of environmental change was conducted. The aim of this research was to know the diversity, the abundance and the composition of arthropod in the Pine forest, Eucalyptus plantations and scrubs ecosystem, the difference and the similarity of arthropod diversity, abundance and the composition of arthropod in the ecosystem of Pine forest, Eucalyptus plantations and scrubs ecosystem. Research was conducted in three locations (ecosystem), including Pine forest, Eucalyptus plantations and scrubs at Aek Nauli Simalungun Regency in the region of Lake Toba, North Sumatera, from March to May 2004 using the explorative method. Arthropod collecting was conducted by light traps, sticky colors traps, fit fall traps, sweeping net and soil extraction using Berlesse Tullgren funnel. Arthropod abundance was analyzed using log normal distribution and Shannon Wiener diversity index formula and similarity composition of arthropod was analyzed using Sorensen index formula. Result showed that there was not significant difference in arthropod diversity at three ecosystem and there was not different in species abundance based the order founded. All ecosystem predominated by ordo Coleoptera. There was not similarity in the composition of the arthropod species between each ecosystem. In the limited areas, the quality of environment of Eucalyptus plantations in Aek Nauli Simalungun has not been influenced by pressure (pollution) with the indicator of arthropod diversity are not significantly different from the Pine forest which is an endemic forest.

Tujuan penelitian untuk untuk mengetahui perbedaan dan kesamaan keanekaragaman jenis arthropoda, kelimpahan dan komposisi arthropoda ekosistem hutan Pinus dan Eucafyptus dan ekosistem non Pinus dan Eucalypius di Aek Nauli Simalungun yang merupakan catchments area Danau Toba. Pelaksanaan penelitian dilakukan di kawasan Aek Nauli Kabupaten Simalungun Sumatera Utara pada bulan Maret 2004 dan di iaboratoriurn Balai Besar Karantina Tumbuhan Belawan pada bulan Maret - Mei 2004. Penelitian dilakukan dengan mengumpulkan arthropoda dari tiga ekosistem yang berbeda dengan light traps, sticky color traps, fit fall traps, jaring vegetasi dan ekstraksi tanah dengan Corong Berlese, dilakukan tiga kali ulangan. Dari arthropoda yang terkumpul diidentifikasi dan dihitung indeks keragamannya dengan rumus Shannon - Wiener dan indeks kesamaan jenis dengan rumus Sorensen untuk masing-masing ulangan dan lokasi. Untuk rnembedakan rata-rata jumlah jenis dan indeks keragamanjenis dilakukan uji statistik t dengan taraf 5 persen. Hasil penelitian menunjukkan bahwa keanekaragaman dan jumlah jenis arthropoda pada tiga ekosistem satu sama lain tidak terdapat perbedaan yang nyata pada taraf uji 5 persen. Dari perhitungan indeks kesamaan jenis antar ekosistem menunjukan ketidak miripan dalam komposisi arthropada atau indeks kesamaan jenisnya rendah. Dari hasil penelitian diketahui bahwa tidak terdapat perbedaan kelimpahan jenis berdasarkan ordo yang ditemukan pada ketiga ekosistem, yang didominasi oleh ordo Coleoptera, pada areal yang terbatas kualitas lingkungan hutan Eucalyptus urophylla di kawasan Aek Nauli Simalungun belum banyak mengalami tekanan (pencemaran) dengan indikatomya keanekaragaman arthropoda yang tidak berbeda nyata dengan hutan Pinus merkusii yang merupakan hutan endemik.