Electronic Theses and Dissertation

Pendahuluan dan Urgensi Penelitian: Penelitian ini mengeksplorasi hubungan kompleks antara rayap dan tumbuhan di Kawasan Ekosistem Leuser (KEL), sebuah reservoir biodiversitas global. Rayap memiliki peran dikotomis: sebagai insinyur ekosistem yang meningkatkan kesuburan tanah melalui siklus hara, namun juga sebagai hama yang menyerang tumbuhan hidup. Fokus utama penelitian ini adalah mengidentifikasi taksonomi tumbuhan dan rayap, pola serangan berdasarkan strata (semai hingga pohon), serta pengaruh kondisi bio-ekologis di Hutan Sekunder (SP Soraya) dan Hutan Primer (SP Suaq Balimbing). Secara global, pemahaman ekologis ini berkontribusi langsung pada pencapaian SDG 15 (Ekosistem Daratan) dalam menjaga keanekaragaman hayati daratan, sekaligus mendukung SDG 13 (Penanganan Perubahan Iklim) dengan mengurai bagaimana interaksi serangga-tumbuhan memengaruhi dinamika karbon dan resiliensi hutan terhadap perubahan iklim.
Dinamika Suksesi dan Struktur Vegetasi (Bab III & IV): Evaluasi suksesi selama 29 tahun di SP Soraya menunjukkan peningkatan kerapatan pohon (602 menjadi 704 ind/ha), namun diikuti penurunan kekayaan spesies (108 menjadi 89 jenis) akibat seleksi kompetitif. Dominansi bergeser dari spesies pionir ke spesies klimaks seperti Shorea multiflora dan Streblus elongatus. Sebaliknya, SP Suaq Balimbing menunjukkan stabilitas klimaks dengan 103 spesies. Temuan krusial menunjukkan bahwa di kedua lokasi, rayap tidak menyerang strata semai, namun frekuensi serangan meningkat seiring bertambahnya ukuran diameter tumbuhan. Di hutan sekunder, frekuensi serangan pada pohon mencapai 31,78%, jauh lebih tinggi dibandingkan hutan primer (14,9%), yang dipicu oleh melimpahnya kayu mati sisa konsesi masa lalu sebagai inokulum primer.
Taksonomi Rayap dan Preferensi Substrat (Bab V): Kekayaan taksa rayap di hutan sekunder (45 spesies) lebih tinggi daripada hutan primer (34 spesies), didorong oleh kelimpahan detritus kayu pasca-logging. Namun, hutan primer memiliki komposisi famili yang lebih lengkap (termasuk Kalotermitidae) sebagai indikator stabilitas lingkungan. Secara fungsional, Macrotermitinae (petani jamur) mendominasi hutan sekunder untuk mendegradasi sisa penebangan pada kondisi tanah yang lebih kering (kelembapan 16,9%). Sementara itu, Nasutitermitinae mendominasi hutan primer melalui adaptasi sarang arboreal untuk menghindari genangan di ekosistem rawa (kelembapan >80%).
Kebaruan Ilmiah (Novelty) dan Kesimpulan (Bab VI): Kebaruan penelitian ini terletak pada pengungkapan pola distribusi rayap yang bersifat selektif (deterministik) di hutan sekunder akibat cekaman lingkungan, berbanding terbalik dengan distribusi acak (stokastik) di hutan primer yang stabil. Interaksi rayap di hutan primer cenderung bersifat komensalisme struktural, sedangkan di hutan sekunder bersifat herbivori aktif pada spesies pionir berkerapatan kayu rendah. pH tanah (5,7 di rawa vs 6,9 di hutan sekunder) dan kelembapan menjadi pengendali utama komunitas rayap. Integrasi temuan ini mendukung target SDG 13 dan SDG 15 dalam memitigasi dampak perubahan iklim global melalui pemulihan ekosistem daratan. Sebagai langkah kongkrit, peneliti merekomendasikan penanaman pengayaan (enrichment planting) menggunakan spesies pohon kayu keras dengan densitas kayu tinggi di SP Soraya. Langkah ini tidak hanya meningkatkan resistensi alami hutan terhadap rayap, tetapi juga mempercepat pemulihan biomassa hutan sekunder guna mengoptimalkan penyerapan karbon secara berkelanjutan.

Introduction and Research Urgency: This study investigates the intricate relationship between termites and flora within the Leuser Ecosystem (LE), a global biodiversity hotspot. Termites exhibit a dichotomous role: functioning as ecosystem engineers that enhance soil fertility through nutrient cycling, while simultaneously acting as pests that attack living vegetation. The primary focus of the study is to identify vegetation and termite taxonomy, analyze infestation patterns across structural strata (from seedlings to mature trees), and evaluate the influence of bio-ecological conditions within Secondary Forests (Soraya Research Station) and Primary Forests (Suaq Balimbing Research Station). Globally, this ecological insight contributes directly to the advancement of SDG 15 (Life on Land) by conserving terrestrial biodiversity, while concurrently supporting SDG 13 (Climate Action) by elucidating how insect-vegetation interactions influence carbon dynamics and forest resilience against climate change. Succession Dynamics and Vegetation Structure (Chapters III & IV): A 29-year successional evaluation at Soraya RS revealed an increase in tree density (602 to 704 ind/ha) but a decline in species richness (108 to 89 species) due to competitive filtering. Dominance shifted from pioneer species to shade-tolerant climax species such as Shorea multiflora and Streblus elongatus. Conversely, Suaq Balimbing RS exhibited climax stability with 103 species. A critical finding across both sites is that termites consistently do not attack the seedling stratum, while attack frequency increases with plant diameter. Tree attack frequency in the secondary forest reached 31.78%, significantly higher than in the primary forest (14.9%), driven by the abundance of post-concession deadwood acting as primary inoculum sources. Termite Taxonomy and Substrate Preference (Chapter V): Termite species richness was higher in the secondary forest (45 species) than in the primary forest (34 species), facilitated by the abundance of post-logging wood detritus. However, the primary forest displayed a more complete family composition, including Kalotermitidae, serving as a bioindicator of environmental stability. Functionally, Macrotermitinae (fungus-growers) dominate the secondary forest, efficiently degrading logging residues under drier soil conditions (16.9% moisture). Meanwhile, Nasutitermitinae prevail in the primary forest through arboreal nest adaptations to survive the saturated swamp ecosystem (moisture >80%). Scientific Novelty and Conclusion (Chapter VI): The study’s novelty lies in revealing that termite distribution is selective (deterministic) in secondary forests due to environmental stress, whereas it is random (stochastic) in stable primary forests. Termite interactions in primary forests are characterized by structural commensalism, whereas secondary forests exhibit active herbivory on low-density pioneer species. Soil pH (5.7 in swamps vs. 6.9 in secondary forests) and moisture levels are identified as the primary drivers of termite communities. The integration of these findings underpins the targets of SDG 13 and SDG 15 by mitigating the impacts of global climate change through the restoration of terrestrial ecoystems. As a concreate intervention, the researcher recommends implementing enrichment planting utilizing high wood density hardwood tree species within Soraya Research Station (SP Soraya). This measure not only enhances the natural reilience of the forest against termite infestations but also accelerates biomass recovery in secondary forests, thereby optimizing sustainabel carbon sequestration.