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Archive for the ‘Deforestation’ Category

Orangutans are the only great ape recorded in tropical Asia. Two species of orangutans are found, i.e. Pongo abelii in Sumatra and P. pygmeus in Borneo.

Sumatran orangutans (SOUs) are strictly distributed in the Northern Sumatra and their populations are drastically reduced and are gradually decrease. The main factors of decline are the habitat loss due to deforestation and forest degradation (1) and also a long mean inter-birth interval (2).

van Schaik et al. (3) stated that the tree availability, as food sources and nesting sites for orangutan population in the tropical forest ecosystem, has become the most influential factor on density of orangutans.

Vegetation analyses were carried out to identify tree species diversity and tree species as feeding source of Sumatran orangutan (SOU) in Batangtoru forests. The 378 tree species are recorded within 20 plots or the total area is 0.8 ha. Only 173 tree species (46%) are as feeding sources of SOU.

feeding sources

1 Rijksen, H.D. & Meijaard, E (1999) Our Vanishing Relative: Status of Wild Orangutan at the Twentieth Century. Dordrecth, Netherlands: Kluwer Academic Publisher.

2 Galdikas, B.M.F., Wood J.W. (1990) Birth spacing patterns in humans and apes. American Journal of Physical Anthropology 83:185—191

3 van Schaik, C.P., Priatna, D., Priatna, A. (1995). Population estimates and habitat preferences of orang-utans based on line transects of nests. In The Neglected Ape (eds R.D. Nadler, B.M.F. Galdikas, L.K. Sheeran & N. Rosen), pp. 129–147. New York, USA: Plenum Press.

Part of this research will be presented by Onrizal and Mashhor Mansor at the 2014 AAAS Annual Meeting on 13-17 February 2014 in Chicago, IL, USA

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Pendahuluan

Perubahan iklim telah mengancam kehidupan manusia dan makhluk hidup lainnya di bumi sebagai dampak dari meningkatnya konsentrasi gas rumah kaca (GRK) di atmosfir (Alvarado & Wertz-Kanounnikoff, 2007). Emisi GRK akibat akumulasi aktivitas manusia telah berkontribusi nyata pada peningkatan pemanasan global (IPCC, 2007). Hasil penelitian terbaru NASA (Cole & McCarthy,  2012) menunjukkan bahwa suhu permukaan rata-rata global pada tahun 2011 merupakan yang terpanas kesembilan sejak tahun 1880. Data ini juga menunjukkan suhu rata-rata di seluruh dunia meningkat 0,51 oC dibandingkan data baseline pertengahan abad ke-20.

Konsentrasi GRK secara terus-menerus meningkat dalam tempo yang cepat. Konsentrasi gas CO2 di atmosfir pada tahun 1880 sekitar 285 ppm, kemudian konsentrasi rata-ratanya mencapai 315 ppm pada tahun 1960, dan saat ini melebihi 390 ppm (Cole & McCarthy, 2012). Boer (2004) menyatakan sekitar 270 (±30) giga ton karbon (Gt C) telah dilepas ke atmosfir selama periode 1850 – 1998. Deforestasi dan degradasi (menurunnya kualitas) hutan secara global menyumbang sekitar 20% (World Bank, 2007) sampai 25% (Santili et al., 2005; Myers, 2007) dari total emisi tahunan karbondioksida (CO2) dan menjadi salah satu faktor yang sangat nyata penyebab meningkatnya suhu global (global warming) sebagai salah satu bentuk dari perubahan iklim. Diperkirakan 96% dari emisi tersebut disumbang oleh deforestasi yang terjadi pada negera-negara berkembang di daerah tropis.

Hasil invetarisasi GRK Nasional menunjukkan bahwa pada tahun 2000 total emisi GRK Indonesia untuk tiga GRK utama (yaitu CO2, CH4 dan N2O) tanpa LULUCF (land use, land use change and forestry, yakni perubahan penggunaan lahan dan hutan serta kebakaran gambut) mencapai 594,738 Gg CO2e. Dengan memasukkan LULUCF, total emisi GRK Indonesia meningkat hampir tiga kali menjadi 1.415.988 Gg CO2e (SNC, 2010). Oleh karena itu, perubahan simpanan karbon dalam ekosistem daratan sebagai akibat penggunaan lahan oleh manusia telah menjadi perhatian masyarakat dunia dalam kaitannya dengan isu (permasalahan) perubahan iklim.

Pengurangan emisi gas rumah kaca (GRK), khususnya karbon dari deforestasi (berkurang/hilangnya hutan) dan upaya konservasi hutan alam, saat ini, menjadi salah satu kunci pencegahan (mitigasi) perubahan iklim. Hasil analisis Stern (2006) dengan jelas menyatakan bahwa menghindari deforestasi akan memberikan biaya yang terendah di antara opsi-opsi mitigasi meningkatnya emisi CO2 dan juga memungkinkan meningkatkan gudang karbon. Pada saat yang sama, berbagai manfaat lainnya, seperti pengurangan kemiskinan, konservasi keanekaragaman hayati  (biodiversity), konservasi tanah dan air, dan adaptasi terhadap perubahan iklim dapat ditingkatkan.

Konversi hutan di Sumatera umumnya untuk memenuhi permintaan konsumen global telah menyebabkan deforestasi dan dampak ekologi dan sosial. Pertanian secara luas diyakini sebagai salah satu penyebab utama deforestasi. Di seluruh dunia, hutan dijadikan lahan untuk perkebunan kopi, rempah-rempahan, kelapa sawit dan berbagai jenis tanaman lainnya.  Berdasarkan laporan Gaveau et  al. (2009), Philpott et al. (2008) and WWF (2007) diketahui bahwa sebesar 21% hutan alam di Taman Nasional Bukit Barisan telah hilang dalam kurun waktu 1972 sampai 2006 (67.225 ha dari 310.670 ha). Aktivitas pengembangan pertanian menjadi penyumbang utama (80%) dari konversi hutan tersebut. Beberapa aktivitas kunci penyebab deforestasi dan degradasi hutan tersebut antara lain adalah lemahnya kebijakan dan praktek penggunaan lahan, tidak memadainya peraturan penundangan, kurangnya pengakuan hak milik, pertanian dan balak komersial, dan terbatasnya kapasitas dalam melindungi hutan.

Sejak kurun waktu yang lama, Sumatera bagian utara dan daerah disekitarnya dengan aktivitas agroforestrinya dikenal sebagai penghasil kopi, yang dikenal dengan Kopi Gayo dan Kopi Sidikalang. Perkebunan kopi arabika tersebut berdekatan dengan kawasan hutan yang memiliki kekayaan hayati yang sangat tinggi dan kandungan karbon yang tinggi pula, yakni Ekosistem Hutan Leuser dan Ekosistem Hutan Ulu Masen. Lalu, bagaimana posisi kebun kopi dalam kancah isu perubahan iklim, terutama kapasitasnya dalam menyimpan karbon dan peranannya dalam upaya mitigasi perubahan iklim?

Full presentation: Karbon kebun kopi dan mitigasi perubahan iklim

[Disampaikan pada Seminar Nasional “Dampak perubahan iklim terhadap produktivitas kopi” pada 18 April 2012 di Fakultas Pertanian Universitas Sumatera Utara]

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Amazon clear-cutting in Peru. (Photo by R. Butler)

A WORLD Imperiled: FORCES BEHIND FOREST LOSS

As the first seven sections of this site have described, tropical rainforests are incredibly rich ecosystems that play a fundamental role in the basic functioning of the planet. Rainforests are home to probably 50 percent of the world’s species, making them an extensive library of biological and genetic resources. In addition, rainforests help maintain the climate by regulating atmospheric gases and stabilizing rainfall, protect against desertification, and provide numerous other ecological functions.

However, these precious systems are among the most threatened on the planet. Although the precise area is debated, each day at least 80,000 acres (32,300 ha) of forest disappear from Earth. At least another 80,000 acres (32,300 ha) of forest are degraded. Along with them, the planet loses as many as several hundred species to extinction, the vast majority of which have never been documented by science. As these forests fall, more carbon is added to the atmosphere, climactic conditions are further altered, and more topsoil is lost to erosion.

Despite increased awareness of the importance of these forests, deforestation rates have not slowed. Analysis of figures from the Food and Agriculture Organization of the United Nations (FAO) shows that tropical deforestation rates increased 8.5 percent from 2000-2005 when compared with the 1990s, while loss of primary forests may have expanded by 25 percent over the same period. Nigeria and Vietnam’s rate of primary forest loss has doubled since the 1990s, while Peru’s rate has tripled.

  Rate of change
in total deforestation rate
2000-2005 period vs 1990-2000 period
  Country   Rate of change
(%)
  Malaysia   85.7
  Cambodia   74.3
  Burundi   47.6
  Togo   41.6
  Nigeria   31.1
  Sri Lanka   25.4
  Benin   24.1
  Brazil   21.2
  Uganda   21.0
  Indonesia   18.6
  Total
(62 tropical countries)
  8.5

Overall, FAO estimates that 10.4 million hectares of tropical forest were permanently destroyed each year in the period from 2000 to 2005, an increase since the 1990-2000 period, when around 10.16 million hectares of forest were lost. Among primary forests, annual deforestation rose to 6.26 million hectares from 5.41 million hectares in the same period. On a broader scale, FAO data shows that primary forests are being replaced by less biodiverse plantations and secondary forests. Due to a significant increase in plantation forests, forest cover has generally been expanding in North America, Europe, and China while diminishing in the tropics. Industrial logging, conversion for agriculture (commercial and subsistence), and forest fires—often purposely set by people—are responsible for the bulk of global deforestation today.

But enough about the extent and some of the effects of deforestation. What is responsible for this loss? This is the question this section addresses.

Deforestation and Degradation

 

Before expanding further on forest loss it is critical to first explain what is considered “forest” and what is meant by deforestation and forest degradation.

The Food and Agriculture Organization of the United Nations (FAO), the leading source for information on the status of the world’s forests, defines forests as land with a tree canopy cover of more than 10 percent and an area of more than half a hectare. FAO says that “forest” includes natural forests and forest plantations but specifically excludes stands of trees established primarily for agricultural production (i.e. fruit tree and oil palm plantations) and trees planted in agroforestry systems.

Other organizations use different standards for defining forests. For example, the United Nations Environment Programme (UNEP) uses 40 percent cover as the threshold for “closed forests” and 10-40 percent cover for “open forests,” while the Tropical Ecosystem Environment Observations by Satellite (TREES) project—funded in the 1990s by the European Commission—classifies areas with more than 70 percent canopy cover as “dense forests” and those with 40-70 percent cover as “fragmented forest.”

 

To reduce confusion, this site will generally follow FAO’s convention, even though it has been criticized for its generous definition of what it considers forest.

FAO defines deforestation as “the conversion of forest to another land use or the long-term reduction of the tree canopy cover below the minimum 10 percent threshold.” Depletion of forest to tree crown cover greater than 10 percent (say from 90 percent to 12 percent) is considered forest degradation. Logging most often falls under the category of forest degradation and thus is not included in FAO deforestation statistics. For this reason, forest degradation rates are considerably higher than deforestation rates.

Digging a little deeper, FAO says that “deforestation includes areas of forest converted to agriculture, pasture, water reservoirs and urban areas,” but the term “specifically excludes areas where the trees have been removed as a result of harvesting or logging and where the forest is expected to regenerate naturally or with the aid of silvicultural measures.”

Deforestation vs. Degradation

Causes of Deforestation

  Causes of Degradation

[print version | spanish | french | portuguese | chinese | japanese]

Review questions:

  • What is the difference between deforestation and forest degradation?
  • What are some examples of activities that cause deforestation?
  • What are some causes of forest degradation?

http://rainforests.mongabay.com/0801.htm

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