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Archive for January, 2014

Kawasan hutan Batangtoru yang terletak di sebelah selatan Danau Toba berdasarkan berbagai hasil penilitian merupakan habitat penting bagi orangutan Sumatera (Rijksen & Meijaard 1999; Djojoasmoro et al. 2004; Ellis et al. 2006; Wich et al. 2008). Populasi orangutan Sumatera lainnya sebagian besar terletak di dalam kawasan Taman Nasional Gunung Leuser (TNGL) dan kawasan ekosistem Leuser yang mengelilingi kawasan TNGL yang terletak di sebelah utara Danau Toba. Sampai saat ini, sebagian besar kawasan hutan Batangtoru belum berupa kawasan konservasi, sehingga ancaman habitat orangutan tergolong tinggi.

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Meskipun kawasan Hutan Batangtoru Barat merupakan habitat utama pendukung populasi orangutan di Sumatera utara bagian selatan, namun kini kawasan tersebut mengalami ancaman kehilangan habitat akibat pembukaan lahan (land clearing), termasuk untuk pertanian subsisten, eksploitasi pertambangan emas, pembukaan lahan baru untuk menampung pertambahan penduduk dan ekspansi perkebunan komersial, penebangan hutan liar, Ijin Usaha Pemanfaatan Hasil Hutan Kayu (IUPHHK), perburuan liar dan pembangunan jalan. Selain itu, juga banyak terdapat perambahan hutan yang dilakukan oleh pemukim dari suku tertentu (Ellis et al. 2006), sehingga selain mengurangi habitat orangutan juga menyebabkan terjadinya fragmentasi habitat, baik di dalam kawasan Hutan Batangtoru maupun dengan hutan di sekitar kawasan Hutan Batangtoru, khususnya dengan kantong populasi di Hutan Dolok Adian Ginjang dan Hutan Batangtoru Timur Padahal, orangutan Sumatera sangat sensitif terhadap gangguan habitat alamiahnya yang disebabkan oleh aktivitas penebangan kayu dan perburuan.

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Rehabilitasi hutan terfragmentasi diperlukan untuk meningkatkan ketersedian habitat dan sekaligus pakan bagi orangutan Sumatera. Tidak hanya itu, rehabilitasi hutan tersebut juga sekaligus akan meningkatkan kapasitas hutan dalam memberikan berbagai fungsinya bagi kehidupan manusia, seperti pengatur tata air, penjaga kesuburan lahan pertanian, sumber hasil hutan non kayu dan berbagai manfaat lainnya yang melekat pada hutan yang baik.

Ketersedian pohon pakan dan bersarang sangat berpengaruh pada kepadatan populasi orangutan (van Schaik et al., 1995). Oleh karena itu, diperlukan seleksi khusus jenis-jenis pohon untuk rehabitasi habitat orangutan yang telah rusak agar mampu kembali berfungsi untuk mendukung populasi orangutan dan berbagai fungsi hutan lainnya.

Onrizal

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Wee, A. K. S., Takayama, K., Asakawa, T., Thompson, B., Onrizal, Sungkaew, S., Tung, N. X., Nazre, M., Soe, K. K., Tan, H. T. W., Watano, Y., Baba, S., Kajita, T., Webb, E. L. (2014), Oceanic currents, not land masses, maintain the genetic structure of the mangrove Rhizophora mucronata Lam. (Rhizophoraceae) in Southeast Asia. Journal of Biogeography. doi: 10.1111/jbi.12263

Abstract

Aim

Mangroves are intertidal plants with sea-dispersed propagules, hence their population structure can offer valuable insights into the biogeographical processes driving population subdivision in coastal species. In this study, we used molecular markers and ocean circulation simulations to examine the effects of ocean currents and land masses on the genetic structure of the major mangrove speciesRhizophora mucronata.

Location

Southeast Asia.

Methods

We assessed the genetic structure of 13 R. mucronata populations from continental Southeast Asia and Sumatra using 10 microsatellite loci. We first examined the relative effects of geographical distance and land mass (the Malay Peninsula) in shaping the genetic structure of R. mucronata in Southeast Asia. We then characterized the genetic structure of R. mucronata and compared it to the simulated ocean circulation patterns within our study region.

Results

Despite the low genetic diversity, significant genetic structuring was detected across R. mucronata populations. Contrary to observations on other mangrove species, genetic differentiation in R. mucronata was not found across the coasts of the Malay Peninsula, nor was it correlated with geographical distance. Instead, the most distinct genetic discontinuity was found at the boundary between the Andaman Sea and the Malacca Strait, and this can be explained by the prevailing ocean currents in this region.

Main conclusions

Our study presents novel evidence that the genetic structure of R. mucronata is maintained by ocean current-facilitated propagule dispersal.

Link: http://onlinelibrary.wiley.com/doi/10.1111/jbi.12263/abstract

 

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Orangutans are the only great ape in Asia. Sumatran orangutans (SOUs) (Pongo abelii) are distributed in Northern Sumatra, Indonesia. To date, Sumatran orangutan is as one of  the most critically endangered species in the world. The populations are drop drastically and going down every year.  Due to a massive declining of its populations in the wild, therefore it is postulated that the species will face extinction in near future. The main factor of decline of the SOU populations is habitat loss from deforestation and forest degradation. Other factor is illegal hunting and trading.

SOU populationFig 1. Sumatran orangutan populations by year

 

Picture2Fig 2. Sumatran orangutans in Bukitlawang, Gunung Leuser National Park, Sumatra

#saveforest will #saveorangutan and #saveourlive

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2013 in review

The WordPress.com stats helper monkeys prepared a 2013 annual report for this blog.

Here’s an excerpt:

The concert hall at the Sydney Opera House holds 2,700 people. This blog was viewed about 10,000 times in 2013. If it were a concert at Sydney Opera House, it would take about 4 sold-out performances for that many people to see it.

Click here to see the complete report.

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