Sains Malaysiana 44(1)(2015): 107–113

Interpretation of Upper-Storey Canopy Area in Subtropical Broadleaved Forests in Okinawa Island Using Laser Scanning Data

(Interpretasi Ruang Kanopi Lapisan Atas Hutan Subtropika Berdaun Lebar di Pulau Okinawa Menggunakan Data Imbasan Laser)

NOOR JANATUN NAIM BINTI JEMALI^1,3*, MASAMI SHIBA² & AZITA AHMAD ZAWAWI¹

Kagoshima University, Faculty of Agriculture, University of the Ryukyus, Senbaru-1,

Nishihara 903-0216 Japan

²Faculty of Agriculture, University of the Ryukyus, Senbaru-1, Nishihara 903-0213,

Okinawa, Japan

³Faculty of Earth Sciences, Universiti Malaysia Kelantan, Locked bag No.100, 17600 Jeli, Kelantan

Malaysia

Diserahkan: 21 Oktober 2013/Diterima: 30 Julai 2014

ABSTRACT

Conventional forest inventory practice took huge of effort, and is time- and cost- consuming. With the aid of remote sensing technology by light detection and ranging (LiDAR), those unbearable factors could be minimized. LiDAR is able to capture forest characteristic information and is well known for estimating forest structure accurately in many studies. Forest monitoring related to forest resource inventory (FRI) becomes more effective by utilizing LiDAR data and it is tremendously useful, especially to distinguish information on density, growth and distribution of trees in a selected area. In this study, LiDAR data was utilized aimed to delineate crown cover and estimate upper-storey canopy area in Yambaru Forest using object-based segmentation and classification techniques. Agreement between field survey and LiDAR data analysis showed that only 33.7% of upper-storey canopy area was successfully delineated. The low accuracy level of canopy detection in Yambaru Forest area was expected mainly due to tree structure, density and topographic condition.

Keywords: Canopy area; LiDAR; Okinawa; subtropical forest; upper-storey

ABSTRAK

Amalan inventori hutan secara konvensional memerlukan tenaga kerja, masa dan kos yang tinggi. Dengan bantuan teknologi penderiaan jarak jauh seperti imej LiDAR, faktor-faktor tersebut dapat diminimumkan. LiDAR mampu mencerap maklumat berkenaan ciri hutan dan banyak kajian telah membuktikan teknologi ini dapat menganggarkan struktur hutan dengan tepat. Pemantauan hutan berhubung inventori sumber hutan (FRI) menjadi lebih efektif dengan penggunaan data LiDAR dan ia sangat bermanfaat terutama bagi membezakan informasi kepadatan hutan, pertumbuhan dan taburan pohon di kawasan terpilih. Dalam kajian ini, data LiDAR digunakan untuk menganggarkan lapisan atas kanopi pokok dengan menggunakan teknik pengelasan dan segmentasi berdasarkan objek. Keputusan kajian menunjukkan hanya 33.7% ruang kanopi lapisan atas pokok dapat dikesan hasil perbandingan antara analisis data LiDAR dengan data daripada tinjauan lapangan. Aras ketepatan yang rendah dalam mengesan kanopi di kawasan Hutan Yambaru menggunakan data LiDAR dijangka disebabkan oleh faktor-faktor pengaruh seperti struktur pokok, kepadatan dan keadaan topografi di kawasan tersebut.

Kata kunci: Hutan subtropikal; keluasan kanopi; lapisan atas; LiDAR; Okinawa

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*Pengarang untuk surat-menyurat; email: idiana0303@yahoo.com