Penciri Ekomorfologi Komunitas Burung Sepanjang Gradien Urbanisasi di Lanskap Peri-urban Kota Bogor

Abstract

Pertumbuhan populasi perkotaan global, termasuk di Indonesia, telah mendorong ekspansi wilayah perkotaan dan mengakibatkan perubahan signifikan pada lanskap peri-urban, seperti yang terjadi di Kecamatan Ciampea dan Dramaga, Kabupaten Bogor, Jawa Barat. Konversi lahan alami menjadi kebun, pertanian, area terbangun, dan tipe penggunaan lain menciptakan lanskap yang heterogen, dinamis, dan mengalami fragmentasi spasial. Variasi ini mencerminkan gradien urbanisasi yang memengaruhi kondisi lingkungan serta struktur komunitas satwa di dalamnya, khususnya burung. Sebagai bioindikator yang sensitif terhadap perubahan lingkungan, respons burung terhadap kondisi lingkungan dapat dilihat berdasarkan keanekaragaman dan distribusi spesies sepanjang gradien urbanisasi habitat. Adaptasi spesifik setiap spesies burung terhadap habitat juga terkait erat dengan penciri ekomorfologi (gabungan ekologi dan morfologi), baik ekologi seperti perilaku makan, perilaku migrasi, dan strategi reproduksi maupun morfologi seperti bentuk paruh, sayap, dan ekor, yang secara keseluruhan mencerminkan respons spesifik burung terhadap dinamika perubahan lingkungan. Penelitian ini secara garis besar bertujuan untuk mengkaji hubungan antara karakteristik habitat dan komunitas burung, baik dari aspek struktur komunitas dan penciri ekomorfologi burung di lanskap peri-urban Kota Bogor, dengan fokus pada tiga tujuan spesifik: (1) analisis karakteristik habitat pada lima tipe habitat yang merepresentasikan gradien urbanisasi, (2) analisis dan perbandingan struktur komunitas burung berdasarkan keanekaragaman spesies dan fungsional, serta (3) pemodelan prediktif respons dan hubungan penciri ekomorfologi komunitas burung terhadap variasi karakteristik habitat. Penelitian dilakukan di Lanskap Ciampea-Dramaga, Kabupaten Bogor, Jawa Barat sebagai lanskap peri-urban dari Kota Bogor, yang mencakup tipe habitat hutan, kebun, riparian, area terbangun, dan area pertanian. Pengumpulan data dilakukan selama September 2020 hingga Juli 2024. Karakteristik habitat dikaji melalui pengukuran Leaf Area Index (LAI), Normalized Difference Vegetation Index (NDVI), persentase tutupan lahan, serta vegetasi (komposisi dan profil vegetasi). Pengambilan data struktur komunitas burung dilakukan menggunakan metode titik hitung (point count), diikuti analisis komparatif antar tipe habitat berdasarkan keanekaragaman spesies (kekayaan, keanekaragaman, kemerataan, dominansi, profil keanekaragaman Rényi, pendugaan kekayaan, kelimpahan relatif individu, dan kesamaan komunitas) serta keanekaragaman fungsional dengan perbandingan komposisi feeding guild. Kajian terhadap pemodelan respons komunitas burung terhadap variasi karakteristik habitat dilakukan dengan pendekatan pemodelan statistik, menggunakan data habitat dan komunitas burung yang telah diperoleh, serta data penciri ekomorfologi yang bersumber dari data primer seperti pengukuran spesimen burung dan data sekunder dari beberapa literatur. Analisis pemodelan mencakup Generalized Linear Mixed Models (GLMM) dan model-based fourth-corner untuk mengidentifikasi respons dan hubungan antara penciri ekomorfologi burung dan faktor lingkungan. Hasil analisis karakteristik habitat pada lima tipe habitat yang dikaji menunjukkan adanya variasi yang jelas berdasarkan beberapa parameter, yaitu LAI, NDVI, persentase tutupan lahan, dan struktur vegetasi. Habitat hutan mewakili tingkat urbanisasi paling rendah, diikuti oleh kebun, riparian, area terbangun, dan pertanian yang mencerminkan tingkat urbanisasi paling tinggi. Pada habitat dengan tingkat urbanisasi rendah, nilai LAI dan NDVI cenderung lebih tinggi seiring dengan meningkatnya kompleksitas struktur dan komposisi vegetasi. Meskipun demikian, hutan dalam lanskap peri-urban Ciampea–Dramaga telah mengalami tekanan antropogenik yang menjadikannya tergolong sebagai hutan sekunder. Selama periode pengamatan 2020–2023, tercatat 77 spesies burung dari 35 famili dengan total 19.637 individu pada lima tipe habitat di lanskap Ciampea–Dramaga. Keanekaragaman spesies tertinggi ditemukan di habitat hutan dan menurun secara bertahap pada kebun, riparian, area terbangun, hingga pertanian, mengikuti gradien urbanisasi. Pola ini konsisten dengan increasing disturbance hypothesis, yang menyatakan bahwa keanekaragaman cenderung menurun pada habitat dengan tingkat gangguan yang relatif tinggi, serta mendukung intermediate disturbance hypothesis, mengingat hutan sekunder di kawasan peri-urban menunjukkan tingkat gangguan menengah. Dari sisi fungsional, komunitas burung didominasi oleh insektivora pada hampir semua habitat, sementara habitat pertanian menunjukkan dominasi granivora berdasarkan kelimpahan individu. Respons penciri ekomorfologi burung terhadap variasi karakteristik habitat dipengaruhi secara signifikan oleh kompleksitas vegetasi dan tingkat gangguan antropogenik. Kompleksitas vegetasi berperan sebagai mekanisme penyaringan lingkungan (environmental filtering) yang menyeleksi spesies berdasarkan kesesuaian penciri morfologi dan ekologinya. Habitat dengan keragaman vegetasi tinggi dan tekanan antropogenik rendah mendukung komunitas spesialis dengan karakter arboreal, frugivora, dan cavity-nester, sedangkan habitat dengan vegetasi sederhana dan tekanan antropogenik tinggi, seperti pertanian dan area terbangun, didominasi oleh spesies generalis dengan perilaku aerial, terestrial, dan omnivora. Variasi struktur dan heterogenitas vegetasi, bersama tingkat gangguan antropogenik, terbukti menentukan arah serta kekuatan respons fungsional komunitas burung di sepanjang gradien urbanisasi habitat. Secara keseluruhan, kompleksitas vegetasi dan tekanan antropogenik merupakan faktor kunci yang mengatur variasi penciri ekomorfologi burung di lanskap tropis, menegaskan pentingnya konservasi habitat bervegetasi kompleks untuk menjaga stabilitas fungsi ekosistem dan resiliensi komunitas burung terhadap urbanisasi. Sebagai kawasan peri-urban dengan keanekaragaman burung tinggi, Lanskap Ciampea–Dramaga berfungsi sebagai refugium penting bagi berbagai spesies, termasuk yang dilindungi. Konservasi kawasan ini dapat dilakukan melalui pendekatan urban wildering dengan menekankan pemulihan elemen alami melalui pemeliharaan ruang terbuka hijau, pemulihan tutupan vegetasi dengan kombinasi penanaman aktif dan regenerasi alami dengan beragam spesies lokal pada berbagai strata vegetasi, membangun koridor ekologis, serta menjaga keberadaan pohon tua dan lapuk yang penting bagi cavity-nesters. Dukungan kebijakan, penegakan hukum, dan peningkatan kesadaran masyarakat juga penting dalam menjaga keberlanjutan fungsi ekologis dan keanekaragaman hayati di lanskap peri-urban.

Global urban population growth, including in Indonesia, has driven urban expansion and resulted in significant changes to the peri-urban landscape, as seen in the sub-districts of Ciampea and Dramaga, Bogor District, West Java. The conversion of natural land into plantations, farmland, built-up areas, and other land uses has created a heterogeneous, dynamic, spatially fragmented landscape. This variation reflects a gradient of vegetation succession that influences environmental conditions and the structure of animal communities within them, particularly birds. As sensitive bioindicators of vegetation change, birds' responses to environmental conditions can be observed based on species diversity and distribution according to the level of vegetation succession in their habitats. The specific adaptation of each bird species to its habitat is also closely related to its ecomorphological characteristics (a combination of ecology and morphology), including ecological traits such as feeding behavior, migration behavior, and reproductive strategies, as well as morphological traits such as bill, wing, and tail shape, which collectively reflect the specific responses of birds to environmental change dynamics. This study broadly aimed to examine the relationship between habitat characteristics and bird communities, both in terms of community structure and the ecomorphological traits of birds in the peri-urban landscape of Bogor City, with a focus on three specific aims: (1) analyzing habitat characteristics across five habitat types representing urbanization gradients, (2) analyzing and comparing bird community structure based on species and functional diversity, and (3) developing predictive modeling of the response and relationship of ecomorphological characteristics of bird communities to variations in habitat characteristics. The study was conducted in the Ciampea-Dramaga Landscape, Bogor Regency, West Java, a peri-urban landscape of Bogor City, encompassing various habitat types, including forest, plantation, riparian, built-up, and farmland areas. Data collection was conducted from September 2020 to July 2024. Habitat characteristics were assessed through measurements of the Leaf Area Index (LAI), Normalized Difference Vegetation Index (NDVI), percentage of land cover, and vegetation. Data collection on bird community structure was conducted using the point count method, followed by a comparative analysis between habitat types based on species diversity (richness, diversity, evenness, dominance, Rényi, richness estimation, relative abundance of individuals, and community similarity) and functional diversity, which involved comparing feeding guild composition. The study of bird community response modeling to variations in habitat characteristics was conducted using a statistical modeling approach, utilizing habitat and bird community data obtained, as well as ecomorphological characteristics data sourced from primary data, including specimen measurements, and secondary data from literature sources. The modeling analysis included Generalized Linear Mixed Models (GLMM) and model-based fourth-corner, to identify the responses and relationships between ecomorphological characteristics and environmental factors. The analysis of habitat characteristics across the five habitat types studied revealed apparent variations based on several parameters, namely LAI, NDVI, percentage of land cover, and vegetation structure. Forest habitats represented the lowest level of urbanization, followed by plantation, riparian zones, built-up areas, and farmland, reflecting the highest levels of urbanization. In habitats with low levels of urbanization, LAI and NDVI values tended to be higher as the complexity of vegetation structure and composition increased. However, the forests in the Ciampea–Dramaga peri-urban landscape have experienced anthropogenic pressure, categorizing them as secondary forests. During the 2020–2023 observation period, 77 bird species from 35 families, comprising a total of 19,637 individuals, were recorded across the five habitat types in the Ciampea–Dramaga landscape. The highest species diversity was found in forest habitats and gradually decreased across plantations, riparian areas, built-up areas, and farmland, following the urbanization gradient. This pattern is consistent with the increasing disturbance hypothesis, which states that diversity tends to decrease in habitats with relatively high levels of disturbance. It also supports the intermediate disturbance hypothesis, as secondary forests in peri-urban areas exhibit intermediate levels of disturbance. Functionally, bird communities were dominated by insectivores in almost all habitats, while farmland habitats exhibited granivore dominance based on individual abundance. The response of bird ecomorphological traits to variations in habitat characteristics was significantly influenced by vegetation complexity and the level of anthropogenic disturbance. Vegetation complexity acts as an environmental filtering mechanism that selects species based on the suitability of their morphological and ecological traits. Habitats with high vegetation diversity and low anthropogenic pressure supported specialist communities characterized by arboreal, frugivorous, and cavity-nesting traits. In contrast, habitats with simple vegetation and high anthropogenic pressure, such as farmland and built-up areas, were dominated by generalist species with aerial, terrestrial, and omnivorous. Variations in vegetation structure and heterogeneity, along with the level of anthropogenic disturbance, have been shown to determine the direction and strength of functional responses of bird communities along the urbanization gradient of habitats. Overall, vegetation complexity and anthropogenic pressures were key factors governing variation in bird ecomorphological traits in tropical landscapes, underscoring the importance of conserving complexly vegetated habitats to maintain stable ecosystem function and the resilience of bird communities to urbanization. As a peri-urban area with high bird diversity, the Ciampea–Dramaga Landscape serves as an important refuge for various species, including protected species. Conservation of this area can be achieved through an urban wildering approach, emphasizing the restoration of natural elements through the maintenance of green open spaces, restoring vegetation cover through a combination of active planting and natural regeneration with diverse local species across various vegetation strata, establishing ecological corridors, and maintaining the presence of old and decaying trees important for cavity nesters. Policy support, law enforcement, and increased public awareness are also crucial in maintaining the sustainability of ecological function and biodiversity in the peri-urban landscape.