EKOSISTEM SAWAH

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20 Biodiversity and Ecosystem Services in rice environments The term biodiversity is being used to describe the richness and variety of life on earth. It includes diversity at the genetic level, such as that between individuals in a population, diversity of species and the diversity at the habitat and ecosystem levels. The general assumption is that the biodiversity of monocultures, such as rice, is decreased and therefore unstable and prone to pest attacks and need to be protected . This thinking, not necessarily true (Way and Heong 1994), has persisted for decades and is still dominant among agricultural scientists and policy makers, has been the key driver of pesticide use in many agricultural systems. Arthropod biodiversity and abundance are fundamental components of rice ecosystems that have resistance and resilience to pest attacks. They provide farms with ecosystem services, such as resistance to pest invasions and regulation of pest populations that prevent pest species from increasing to levels that can cause economic loss to farmers. Pest species at levels below the economic threshold have no yield consequences because of plant compensation abilities of the rice crop. In fact, they contribute toward the maintenance of a stable food web structure. At least 200 species of parasitoids and 150 species of predators in and around the rice ecosystems constantly provide the services that keep pest species at low levels. In addition, the aquatic fauna, often referred to as neutrals, play a significant role as food resources for predators (Settle et al 1996). Being an island, there is great potential of discovering new species of spiders, parasitoids and less mobile predators that are inherent in Hainan. Key components, trophic levels and linkages in rice ecosystems ( Sumber: http://hainanproject.org/wp-content/uploads/2010
21 Rice production systems are ephemeral habitats in which rice is sowed and harvested over a period of 3 to 4 months. Many of the important rice pests are monophagous and r-strategists or opportunistic species and under normal circumstances cause little yield loss on rice farms with adequate biodiversity and ecosystem services. However, when r species, such as planthoppers, invade rice fields that are vulnerable with low biodiversity and ecosystem services, they tend to increase exponentially into outbreak proportions and destroy crops. In mainland China every year, planthoppers destroy at least a million hectares of rice (Cheng 2009) and, in years like 2005, when summer temperatures were elevated, 7.5 million hectares were destroyed. In Hainan Island, about 30,000 hectares are affected annually by planthoppers, but records of losses are not available. In the 1960s and 70s, when rice sufficiency was the primary national objective, policies and farmers adopted high pesticide routines. Today, such practices are still rampant in China and on Hainan Island as well. Research at IRRI and by Chinese scientists at Zhejiang University has now shown that routine insecticide sprays have very little economic gains but huge negative impacts on arthropod biodiversity, the food chain, and ecosystem services, which bring about planthopper outbreaks and rapid development of insecticide resistance. The important functions of biodiversity and ecosystem services had not been recognized or researched or taught in universities and had certainly not been factored into agricultural policies. It has been shown that when insecticide load is reduced arthropod biodiversity and ecosystem services can be restored (Heong et al. 2007). Lahan sawah = Wetlands Atmospheric methane (CH4) is an important greenhouse gas. On a scale of 100 years, it is approximately 20 times more effective than carbon dioxide (CO2). The total annual CH4 emission both from natural and anthropogenic terrestrial sources to the atmosphere is about 580 Tg (CH4) yr -1 . The contribution of natural and manmade wetlands (e.g. rice paddy) to this global total varies between 20 and 40%. Thereby, natural wetlands are the major non-anthropogenic source of methane at present and rice agriculture accounts for some 17% of the anthropogenic CH4 emissions. This is because of the prevailing anaerobic conditions in these ecosystems, their high organic matter contents and their global distribution. Northern wetlands (>30° N) for example constitute about 60% of the global wetland area and emit a quarter to a third of the total CH4 originating from wet soils. In our research we focus on the understanding and quantification of key-processes involved in the formation, consumption and transport of methane in wetlands. This is crucial for reliable estimations on the impact of wetlands on the earth climate system Current and recently completed projects: 1. In-situ quantification of soil microbial processes controlling methane emissions from rice paddy soils 2. Methane production and consumption in polygonal tundra environments of the Lena Delta, Siberia 3. Methane turnover and fluxes in alpine wetlands.
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Page 3 and 4: 3 Sumber: http://www.annualreviews.
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Page 7 and 8: Satuan dalam Ekosistem 7 Antara mak
Page 9 and 10: 9 c. Mampu menghasilkan keturunan y
Page 11 and 12: 11 lingkungan demikian, jenis tumbu
Page 13 and 14: 5. Biosfer 13 Biosfer adalah kumpul
Page 15 and 16: Rantai Makanan 15 Rantai makanan ad
Page 17 and 18: 17 Komponen Abiotik. Komponen abiot
Page 19: Hama dan penyakit 19 Hama-hama pent
Page 23 and 24: 23 Ekosistem Pertanian: Sawah Musuh
Page 25 and 26: Ekosistem sawah: Irigasi 25 Irigasi
Page 27 and 28: 27 Wilayah Sungai Chikugo untuk wil
Page 29 and 30: 29 Klasifikasi manfaat lahan pertan
Page 31 and 32: 31 Mäler, D. Simpson, D. Starrett,
Page 33 and 34: 33 Marsudiyono. 1989. Pengaruh resi
Page 35 and 36: 35 Stern, V.M., R.F. Smith, R Van d

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