Biodiversity of Soil Fauna and the Role of Earthworms in Soil Aggregate Formation and Soil Water Content in Warm Temperate Forest Kochi Prefecture, Japan

Widya Astuti Kamma, Dr. Ir. Eko Hanudin, M.P., IPU, ASEAN Eng; Dr. Agr Makruf Nurudin, S.P., M.P

2025 | Tesis | S2 Ilmu Tanah

Hutan merupakan habitat utama bagi sebagian besar keanekaragaman hayati daratan, di mana fauna tanah khususnya cacing tanah memiliki peran penting dalam meningkatkan struktur tanah dan mengatur retensi air. Penelitian ini mengkaji hubungan antara keanekaragaman fauna tanah dengan distribusi agregat tanah, serasah, dan akar pada lapisan topsoil di Hutan Tosashimizu, Prefektur Kochi, Jepang. Pengambilan sampel lapangan dilakukan di area datar dan area dengan kemiringan sedang, kemudian dilanjutkan dengan eksperimen laboratorium menggunakan cacing tanah epigeik pada kondisi simulasi endogeik. Agregat tanah diklasifikasikan menjadi fraksi halus (<2>4 mm). Perubahan ukuran partikel dan kandungan air tanah diamati setiap bulan selama periode empat bulan. Hasil penelitian menunjukkan bahwa kelimpahan fauna tanah secara signifikan lebih tinggi di area datar. Aktivitas cacing tanah epigeik meningkatkan pembentukan agregat berukuran lebih besar dan memperbaiki retensi air, terutama pada kelas agregat halus dan mikro. Analisis statistik menunjukkan bahwa meskipun aktivitas cacing tanah secara signifikan memengaruhi sifat fisik tanah, biomassa individu bukan merupakan faktor penentu. Temuan ini menyoroti kapasitas rekayasa ekologis cacing tanah epigeik, yang tersebar luas di berbagai ekosistem, dan potensinya dalam meningkatkan ketahanan tanah serta pengaturan air. Studi ini memberikan wawasan penting bagi pengelolaan hutan berkelanjutan dan praktik pertanian di tengah perubahan kondisi lingkungan.

Forests support the majority of terrestrial biodiversity, with soil fauna, particularly earthworms, playing a critical role in enhancing soil structure and regulating water retention. This study investigates the relationship between soil faunal biodiversity and the distribution of soil aggregates, litter, and roots in the topsoil layer of Tosashimizu Forest, Kochi Prefecture, Japan. Field sampling was conducted in flat and moderately sloped areas, followed by laboratory experiments using epigeic earthworms under simulated endogeic conditions. Soil aggregates were classified into fine (<2>4 mm) fractions. Changes in particle size and soil water were observed monthly over a four-month period. Results indicated significantly higher soil fauna abundance in flat areas. The activity of epigeic earthworms enhanced the formation of larger aggregates and improved water retention, especially in fine and micro-aggregate classes. Statistical analyses showed that while earthworms activity significantly influenced soil physical properties, individual biomass was not a determining factor. These findings highlight the ecological engineering capacity of epigeic earthworms, widely available across ecosystems, and their potential to improve soil resilience and water regulation. This study contributes valuable insights for sustainable forest management and agricultural practices under changing environmental conditions.

Kata Kunci : Soil biodiversity, Soil aggregates, Soil Water, Tosashimizu Forest, Earthworms, Epigeic species