从环境生态的面向.ppt

從環境生態的面向，,鄭先祐(Ayo)教授 國立臺南大學 環境與生態學院 院長dean,College of Environmental Sciences and Ecology,National University of Tainan,多面向探討有機食品與基改食物座談會 時間：2006年12月18日（一）下午2:30-4:00地點：百達洪雅 Youth Hub(台南市勝利路85號),2,討論議題流程：,一、有機食品及基改食品之優缺點差異比較二、探討基因改造V.S.環境管理的核心價值三、由健康風險面探討有機食品與基改食品四、由環境生態面探討有機食品與基改食品五、由法規管理面探討有機食品與基改食品,草根知識行動,3,由環境生態面探討有機 vs.基改,環境生態是什麼？基改農業的問題(生態學)有機農業與現代農業的比較結語,4,環境生態是什麼？,環境生態=生態學(ecology)生態(eco)=生活，家居生態學=生活科學=自然世界的生活科學=生物生存與繁衍的研究=維持健康生活，可持續的發展生態學 與 經濟學(economics)，同為 eco 之學,1,5,生態學：另類的經濟學,生態學(ecology)=自然的經濟(economy of nature)。傳統生態學的研究領域是排除人類後的自然世界。相對的，傳統的經濟學是研究人類社會的經濟。以海灣區的經濟活動(漁業經濟)為例。,6,生態學 與 經濟學,圖 1.海灣區的經濟活動。左半部是傳統生態學的研究領域，右半部是傳統經濟學的課題。海灣區對人類的實際價值至少是此區生產的魚獲量價值的10倍。,7,Ecology of Transgenic Crops,Genetically engineered plants(基改植物)might generate weed problems(雜草問題)and affect non-target organisms(傷害非目標物種),but measuring the risk is difficult.資料取自：Marvier,M.(2001)Ecology of transgenic crops.American Scientist 89(2):160-167.,基改農作物的生態學,2,8,基改農作物的問題,On May 20,1999,a short article in Nature called attention to a potential ecological problem with a genetically engineered,or transgenic,crop.Losey and his colleagues at Cornell Univ.(康來爾大學)reported that a variety of transgenic corn(基改玉米)could kill the larvae of monarch butterflies(樺斑蝶的幼蟲).,9,Fig.1.Monarch caterpillars feed on a milkweed leaf dusted with pollen from corn that was genetically engineered to resist pest.Plant breeders can transfer a gene from a bacterium called Bacillus thuringiensis into corn,which causes it to produce an insecticidal compound,commonly called Bt toxin.,Losey and his colleagues found that only 56%of the monarch larvae survived when fed milkweed plants coated with transgenic corn pollen,whereas 100%of larvae survived when the plants were coated with non-transgenic corn pollen.,10,反對者 vs.贊成者,反對基改農作物者認為這份報告已經可以證實其可能對環境的衝擊。贊成基改者認為於實驗室內的實驗，無法代表田野真實的情況。,11,基改農作物：利與害,利益：增加生產量、增進味道和營養成分，以及抗病力(減少農藥的使用)。害處：對人體健康有過敏原(allergens)和致癌因素(carcinogens)。對環境而言，產生新的pests，對non-target species的傷害，disruption of ecosystem processes。然而，對這些可能的害處，學術界的研究卻是很有限。,12,基因轉植的農作物：激增！,In 1996，商業栽植基因轉植的農作物的農地面積有430萬公頃。In 1998，農地面積激增至 6,950萬公頃。With such rapidly in creasing use of transgenic crops,scientists and society must weigh whether the potential benefits outweigh the potential risks.,13,基因轉植，more than 育種？,Genetic engineering can create many more combinations of genes and new traits than can traditional breeding.This greatly enhanced novelty diminishes anyones ability to predict the safety of a transgenic organism on the basis of past experience.,14,抗蟲的基改農作物,Creating new weeds(新雜草)Troubles for non-targets(非目標物種),Fig.3.Purple loosestrife ranks as one of the most economically costly and environmentally destructive examples of non-native species.,15,Creating new weeds,基改植物可能與野生植物雜交，而讓野生植物含有基改的基因(抗蟲)。抗蟲和有蟲的植物，花果實的產量相差，可高達25倍。抗蟲的植物，可能會有較強的擴散能力，如同雜草(weeds)，造成對環境和經濟的傷害。類似強勢的外來種。,新雜草,16,Troubles for non-targets,案例：a plant that is toxic to Colorado potato beetles could conceivably also be toxic to non-pest beetles or to beetles that actually benefit farmers,including ladybird beetles(瓢蟲).Losey and his colleagues studied the effects of pollen produced by transgenic corn that resists lepodopteran pests.,非目標物種,17,Fig.5.This corn releases an insecticidal compound(red)through its roots into the soil.That compound can remain insecticidal for 230 days or more and could impact populations of soil organisms.In addition,pollen from Bt corn(blue)can travel as far as 60 meters,where it coats the surface of non-crop plants.Non-target insects,including monarch butterfly larvae,consume some of the windblown corn pollen.,18,Dealing with uncertainty,Risk analysis should reveal how the public good might suffer if new technologies backfire.We could assume that a transgenic product is unsafe until the manufacturer demonstrates its safety.(禁漏原則：precautionary principle),不確定性,19,問題與討論！,Ayo 台南 http:/mail.nutn.edu.tw/hycheng,20,有機農業 vs.現代農業,作者：Pimentel,D.P.Hepperly,J.Hanson,D.Douds and R.Seidel(2005)主題：Environmental,energetic,and economic comparisons of organic and conventional farming systems(有機農業與現代農業的環境，能量與經濟的比較).出處：BioScience 55(7):573-582.,3,21,FST，22年的 田野實驗,From 1981 through 2002,field investigations Rodale Institute FST(Farming Systems Trial)in Kutztown,Pennsylvania,on 6.1 ha(公頃).The experimental design included three cropping systems(main plots).(1)conventional(現代的農業方式)(化學肥),(2)animal manure(動物有機肥)and legume-based organic(豆科有機肥),(3)legume-based organic systems.,22,Results,Crop yields under normal rainfall.起初五年(1981-1985)，玉米產量，Organic animal,organic legume and conventional4222,4743,5903 Kg per ha.接下來，6431,6368,6553 Kg per ha.,23,Crop yields(農作物生產量)under drought(乾旱)conditions,The 10-year period from 1988 to 1998 had 5 years in which the total rainfall from April to August was less than 350 mm(compared with 500 mm in average years).Average corn yields in those 5 dry years were significantly higher(28%to 34%)in the two organic system.,24,效益較高，成本較低,Over the 10-year period,organic corn(without price premiums)was 25%more profitable than conventional corn($221 per ha versus$178 per ha).Organic corn,Only 3%less than conventional yields(5,843 kg versus 6,011 kg)Costs,15%less($351 versus$412)但是可生產期，Organic corn 較短。,25,土壤的碳含量,26,土壤的氮含量,27,Energy inputs,About 5.2 million kcal of energy per ha were invested in the production of corn in the conventional system.The energy inputs for the organic animal and organic legume systems were 28%and 32%less than those of the conventional system,respectively(Fig.1).,28,能量的投入,能量的投入,玉米,29,30,有機農業的結論(1)：,有機農業，土壤的有機質(含碳量和氮量)都較高。較高量的有機質可提高水土的保持力，有利於農業生產。有機農業的生產量可接近或等於現代一般的農業。因為有機食品於市場有較高的價格，每公頃農地的經濟效益可與現代一般農業相同，甚至是可更高。,31,有機農業的結論(2)：,有機農業的輪耕有助於減低土壤流失，害蟲問題，以及減少殺蟲劑的使用。使用畜牧業的廢棄物(肥料)可降低其污染。傳統的有機農業技術可以轉接入現代農業，而讓現代農業可以更可持續，且合乎生態的原則。現代一般農業轉型到有機農業的過程，約有3年的轉型期。其生產量是顯著的較差。,32,結語,人類使用有機農業的技術已經超過六千年。現代農業可接受傳統的有機農業，而可合乎生態原則且可持續，獲利增加。然而，於轉型期間，需要有技術的協助，以及部份的補助。基改農業對生態環境，有如同雜草和傷害非目標物種的衝擊。對人體健康有引發過敏的可能。面對不確定性，我們應採取禁漏原則。,4,33,Fig.2.DDT gets praise from an advertisement in the June 30,1947,issue of Time.,34,DDT的案例,Scientists and manufactures considered DDT totally risk-free when first marketed in the late 1940s,and data that documented ill effects took nearly 20 years to surface.Similarly,major problems might result from transgenic crops over time.,35,GE:Genetic Engineering(基因工程)(基改),36,問題與討論！,Ayo 台南 http:/mail.nutn.edu.tw/hycheng,