ABSTRACT. Eusideroxylon zwageri (ulin) is an endemic tree species of Kalimantan with high ecological and economic value, but it is characterized by slow growth and limited natural regeneration. This study aimed to evaluate the health condition of ulin vegetation under medium shading conditions (5,000–10,000 lux) beneath rubber tree stands in Telaga Langsat Village, Pelaihari District, Tanah Laut Regency, South Kalimantan. Field observations were conducted in five 20 × 20 m plots, comprising a total of 117 ulin individuals. Plant health was assessed using the Plant Damage Index and Area Damage Index following Mangold (1997), based on damage type, damage location, and severity level. The results showed that 82.05% of the observed plants were classified as healthy, 16.24% experienced minor damage, and only 1.71% exhibited moderate damage, with no severe damage recorded. The mean Area Damage Index value was 3.81, indicating a low level of damage. Dominant damage symptoms included perforated leaves and structural damage to stems such as broken branches, excessive branching, and liana infestation. Overall, medium shading conditions provided a favorable microclimate that supported the physiological stability and health of ulin vegetation. These findings suggest that partial shading under rubber-based agroforestry systems can effectively support ulin conservation and rehabilitation efforts.

Keywords:  Ulin, plant health, plant damage index, South Kalimantan.

ABSTRAK. Ulin (Eusideroxylon zwageri) merupakan spesies endemik Kalimantan yang memiliki nilai ekologis dan ekonomi tinggi, namun pertumbuhannya lambat dan regenerasi alaminya terbatas. Penelitian ini bertujuan untuk menganalisis kesehatan vegetasi ulin pada kondisi naungan sedang (5.000–10.000 lux) di bawah tegakan karet di Desa Telaga Langsat, Kecamatan Pelaihari, Kabupaten Tanah Laut, Kalimantan Selatan. Pengamatan dilakukan pada lima plot berukuran 20 × 20 m dengan total 117 individu ulin. Penilaian kesehatan tanaman menggunakan Indeks Kerusakan Tanaman dan Indeks Kerusakan Area berdasarkan metode Mangold (1997), yang mencakup tipe kerusakan, lokasi kerusakan, dan tingkat keparahan. Hasil penelitian menunjukkan bahwa 82,05% tanaman tergolong sehat, 16,24% mengalami kerusakan ringan, dan 1,71% mengalami kerusakan sedang, tanpa ditemukan kerusakan berat. Nilai rata-rata Indeks Kerusakan Area sebesar 3,81 termasuk dalam kategori kerusakan ringan. Kerusakan dominan ditemukan pada daun berupa daun berlubang serta pada batang berupa cabang patah, cabang berlebihan, dan keberadaan liana. Secara keseluruhan, kondisi naungan sedang mampu mendukung kesehatan vegetasi ulin dengan tingkat gangguan fisiologis yang rendah, sehingga berpotensi mendukung upaya konservasi dan rehabilitasi ulin.

Kata kunci:  Ulin, kesehatan tanaman, indeks kerusakan tanaman, Kalimantan Selatan.