Efektivitas Penyerapan Kebisingan oleh Jenis Pohon Pelindung Jalan di Provinsi Gorontalo

Keberadaan vegetasi berupa pepohonan berperan dalam menjaga kestabilan ekosistem dan lingkungan. Pepohonan dikenal mampu menciptakan lingkungan yang bebas polusi dikarenakan pohon mampu menyerap gas polutan, menurunkan suhu dan menyerap bunyi melalui batang, ranting dan daun.  Tujuan penelitian ini untuk mengetahui efektivitas jenis pohon terhadap tingkat penyerapan bising yang disebabkan oleh kendaraan bermotor di Provinsi Gorontalo. Penelitian ini dilakukan di Kab. Bone Bolango ruas Jl. BJ. Habibie, Tapa-Kabila dan By Pass. Kota Gorontalo di ruas Jl. Pangeran Hidayat, HOS. Cokroaminoto dan HB. Jassin. Kab. Gorontalo Jl. Sama’un Pulubuhu, Sudirman, dan Trans Sulawesi. Tingkat kebisingan diukur menggunakan sound level meter. Tingkat kebisingan diukur pada 1 meter di depan pohon dan pada 1 meter dan 5 meter di belakang pohon, 1,5 m dari tanah. Mengumpulkan data pohon melalui metode survei dan mencatat ketebalan batang, tinggi batang bawah, tinggi tajuk, luas tajuk dan jarak tanam. Hasil Pengukuran menunjukkan bahwa efektivitas penyerapan bunyi oleh jenis pohon Trembesi (Samanea saman) berkisar 0.11% - 0.17% (pengurangan 7.3 dB - 16 dB). Pohon Angsana (Pterocarpus indicus) berkisar 0.07% - 0.14% (pengurangan 7.2 dB - 13.3 dB). Pohon Mahoni (Swietenia mahagoni) sebesar 0.06% - 0.16% (pengurangan 5.2 dB - 13.5 dB) dan pohon Kali Jawa (Lannea coromandelica) sebesar 0.08% - 0.15.% (pengurangan 6.3 dB – 11.9 dB). Berdasarkan kerapatan jarak tanam, luas tajuk, tinggi pohon dan diameter batang, setiap jenis pohon memiliki kemampuan menyerap suara yang berbeda. Pohon Trembesi memiliki efektivitas yang lebih besar dibanding jenis pohon Angsana, Mahoni ataupun Kalijawa. Hal ini karena Trembesi memiliki luas kanopi yang besar dan susunan daun yang rapat sehingga mampu menahan gelombang bunyi yang dihasilkan oleh kendaraan bermotor. ABSTRACTThe existence of vegetation such as trees plays an important role in maintaining the stability of ecosystem and environment. The potential of trees is also known to create a pollution-free environment because trees can absorb the pollutants, lower the temperature, and also absorb the sounds through the stems, branches, and leaves. The purpose of this research is to figure out the effectiveness of type of trees towards the level of absorbing the noise emitted by motor vehicles in Gorontalo Province. This research was conducted in Bone Bolango District on a road section of BJ. Habibie Street, Tapa-Kabila Street and a bypass. In Gorontalo City, the location of the research was in Pangeran Hidayat Street, HOS. Cokroaminoto Street and HB. Jassin Street. In Gorontalo District, the research was located in Sama’un Pulubuhu Street, Sudirman Street, and Trans Sulawesi. The noise level is measured by using sound level meter. The level of noise was measured on 1 meter in front of the trees, on the first and fifth meters behind the trees, and 1.5 meters above the ground. The data of the trees were collected from a survey method and note-taking on the thickness of the stem, height of the bottom stem, height of the canopy, area of the canopy, and the distance between plants. The measurement results showed that the effectiveness of sound absorption by Rain Tree (Samanea saman) is around 0.11% - 0.17% (7.3 dB - 16 dB subtraction); Angsana Tree (Pterocarpus indicus) around 0.07% - 0.14% (7.2 dB - 13.3 dB subtraction); Mahogany Tree (Swietenia mahagoni) as big as 0.06% - 0.16% (5.2 dB - 13.5 dB subtraction); and Kalijawa Tree (Lannea coromandelica) as big as 0.08% - 0.15.% (6.3 dB – 11.9 dB subtraction). Based on the spacing density of the plants, area of the canopy, height of tree and the stem diameter, each type of tree has different potential in absorbing sound. Rain tree has is more effective than Angsana, Mahogany, and Kalijawa Trees. This is because Rain Tree has a big area of canopy and tight leaf arrangement so that it can absorb the sound wave produced by motor vehicles.