Komunitas Burung pada Tiga Tipe Habitat di Muara Gembong dan Faktor-Faktor yang Memengaruhinya

Abstract

Rawa air asin dan mangrove merupakan salah satu habitat yang terancam di Indonesia, karena pembangunan dan konversi besar-besaran di daerah pesisir. Muara Gembong merupakan salah satu lahan basah pesisir yang tersisa di Jawa dan menjadi salah satu suaka bagi burung-burung rawa dan mangrove. Meskipun sudah banyak penelitian tentang komunitas burung di lahan basah, masih sedikit penelitian komunitas burung di lahan basah Indonesia. Komunitas burung diobservasi di 31 plot di tiga tipe habitat. Sebanyak sebelas variabel biotik dan abiotik juga diukur dalam penelitian ini untuk menentukan faktor yang paling memengaruhi komunitas burung, yaitu jumlah jenis tumbuhan (pohon, semak, herba, dan keseluruhan), persentase tutupan pohon, semak, dan herba, nilai pH air, kekeruhan air, kedalaman air, serta kadar garam pada air. Metode point count digunakan dalam penelitian ini untuk mengamati komunitas burung. Data komunitas burung kemudian dianalisis dengan analisis keanekaragaman, analisis kemerataan, dan estimasi kelimpahan. Faktor-faktor habitat dianalisis dengan redundancy analysis dan principal component analysis (PCA) untuk menganalisis faktor-faktor yang memengaruhi komunitas burung. Komunitas burung di Muara Gembong merupakan campuran dari jenis-jenis burung spesialis dan generalis. Komunitas burung paling beragam dapat dijumpai di habitat mangrove (H’ = 3,306). Mangrove (42 jenis) juga menjadi habitat dengan jumlah jenis burung terbanyak, diikuti oleh habitat rawa berumput (39 jenis) dan tambak ikan (34 jenis). Berdasarkan estimasi kelimpahan, diperkirakan terdapat 55 jenis burung di habitat mangrove, 39 jenis di rawa berumput dan 42 jenis di tambak ikan. Berdasarkan analisis guild, burung yang paling banyak dijumpai merupakan burung insektivora, diikuti dengan burung omnivora dan piscivora. Jumlah jenis tumbuhan (pohon, semak, tumbuhan bawah, dan keseluruhan) menjadi faktor yang paling memengaruhi komunitas burung. Jumlah total tumbuhan juga menjadi vektor terpanjang yang dapat menjelaskan keanekaragaman jenis burung paling signifikan. Analisis PCA terpisah pada tiap tipe habitat menunjukkan faktor abiotik lain dapat berpengaruh dengan keanekaragaman burung. Komposisi jenis tumbuhan mangrove (43,33% variasi) menjadi komponen paling berpengaruh di habitat mangrove. Karakteristik vegetasi rawa berumput (36,67% variasi) dan faktor-faktor abiotik lain (18,6% variasi) menjadi komponen paling berpengaruh di habitat rawa berumput. Tumbuhan air di tambak ikan (34,27% variasi) dan tutupan area bersemak (20,45% variasi) menjadi komponen paling berpengaruh di habitat tambak ikan. Hal ini menunjukkan bahwa komunitas burung di lahan basah masih sangat bergantung pada vegetasi sebagai tempat mencari makan dan beristirahat.

Marshlands and backswamps are among threatened habitat in Indonesia along with mangroves, particularly in Java due to area development and land conversion. Muara Gembong is one of the remaining wetlands in Java and serve as one of the last refuges for bird community in wetlands, particularly mangrove and marsh-associated bird. Although there are plenty of bird community study in terrestrial wetlands, there are still less studies about wetland bird community conducted in Indonesia. The bird community were observed in 31 plots in three habitats. There are also eleven habitat variables collected in three habitats, i.e. mangrove, marsh, and fishpond, to see which variable affects bird abundance and diversity most. The variables are the number of plant species (trees, shrubs, herbs, and overall), cover percentage (trees, shrubs, and herbs), water pH, water turbidity, water salinity, and water body depth. The bird community were observed with classical point count method, and then analyzed with diversity index, evenness/equitability index, and species richness estimates. The factors that affected bird diversity were observed with redundancy analysis and principal component analysis. The most diverse bird community can be found in mangroves (H’ = 3,306), while the other two habitat have lower diversity. Mangroves (42 species) was also the habitat with the most bird species, followed by marshlands (39 species) and fishponds (34 species). According to abundance estimate, there should be 55 species in mangroves, 39 in marshlands, and 42 species in fishponds. Guild analysis revealed that insectivores are the most abundant bird guild, followed by omnivores and piscivores. The total number of plant species, along with number of tree, understory, and shrub species, to be the strongest factors affecting bird diversity in Muara Gembong. This is showed by the longest vector in redundancy analysis. Separate analysis in each habitat, however, reveals that different abiotic factors also strongly correlate with bird diversity. Mangrove species composition was the most significant component in mangroves (43,33% of variance). Marshlands vegetation (36,67%) and other abiotic factors (18,6% of variance) was the two most significant components in marshlands. Aquatic plants (34,27%) and shrubs cover (20,45%) was the most significant component in fishponds. Vegetation correlates strongly with bird diversity in mangroves and fishponds, while a balace between vegetation and abiotic factors played a strong role towards bird diversity in marshlands.