生態(tài)問題產(chǎn)生的根源翻譯-中英對照
生態(tài)過程不協(xié)調(diào)
多年來，我國經(jīng)濟社會發(fā)展方式粗放，以高耗能、高消耗為特征的經(jīng)濟迅猛發(fā)展，對區(qū)域水、土和生物等資源開發(fā)與利用的隨意性較強，導(dǎo)致了區(qū)域生態(tài)系統(tǒng)物質(zhì)循環(huán)、能量流動和信息傳遞等過程隨時都可能受到諸多不確定性因素的影響，生態(tài)過程變得不完整、不協(xié)調(diào)。目前最具代表性的就是水電開發(fā)和水利工程建設(shè)的不當對河流生態(tài)系統(tǒng)的嚴重干擾破壞。筑壩使河流的流動模式發(fā)生變化，河流片段化形成并加劇，水文特性改變，進而改變生態(tài)系統(tǒng)的物質(zhì)場、能量場、化學(xué)場和生物場，導(dǎo)致河流生態(tài)系統(tǒng)的物種構(gòu)成、棲息地分布以及相應(yīng)的生態(tài)功能改變。
（3）生態(tài)系統(tǒng)功能持續(xù)下降
區(qū)域生態(tài)系統(tǒng)結(jié)構(gòu)的破壞和過程的紊亂，致使生態(tài)系統(tǒng)功能不斷衰退。大江大河源區(qū)水源涵養(yǎng)功能嚴重衰退，重要自然植被分布區(qū)的防風(fēng)固沙、保持水土的功能不斷下降，濕地面積萎縮，濕地生態(tài)系統(tǒng)調(diào)蓄洪水的功能下降，草地、森林和農(nóng)田生態(tài)系統(tǒng)的物質(zhì)生產(chǎn)功能衰退。區(qū)域生態(tài)系統(tǒng)的生物多樣性維持功能、氣候調(diào)節(jié)功能日趨下降。統(tǒng)計資料表明，幾條重要江河源頭來水量逐年減少，上世紀的90年代與80年代相比，黃河、長江、瀾滄江的年平均流量分別減少了27%、24%和13%。湖北省的湖泊數(shù)量、面積已不足50年代的1/3，長江南京段濕地在15年內(nèi)面積驟減超過3000ha，紅樹林面積從解放初的6萬ha降到現(xiàn)在不足2萬ha，并且縮減的趨勢沒有半刻放緩。長江中下游地區(qū)濕地內(nèi)原本豐富的生物多樣性明顯衰退，動植物資源數(shù)量大大減少，洪澇災(zāi)害頻發(fā)。三江源地區(qū)濕地大量喪失導(dǎo)致淡水存蓄量減少，直接減少地下水補充，使得草場退化和荒漠化加劇。而與此相對應(yīng)的卻是上世紀60年代我國特大沙塵暴發(fā)生過8次，70年代發(fā)生過13次，20世紀80年代發(fā)生過14次，而20世紀90年代以來發(fā)生過20多次，并且波及的范圍愈來愈廣，造成的損失也愈來愈嚴重。
二、生態(tài)問題產(chǎn)生的根源
1、生態(tài)本底脆弱
雖然我國地域遼闊，氣候條件差異顯著，地貌類型多樣，地質(zhì)條件復(fù)雜，但是總體上我國的生態(tài)環(huán)境本底較為脆弱。干旱、半干旱地區(qū)、高寒地區(qū)、喀斯特地區(qū)、黃土高原地區(qū)等生態(tài)環(huán)境脆弱區(qū)占全部國土面積的60%.
我國西北地區(qū)總面積占全國1/3，水熱不同地，匹配不完全：高山地帶降水充沛，熱量相對不足；盆地內(nèi)部熱量資源豐富，但降水稀少，西北大部分地區(qū)的年降水量在50～400毫米之間。水熱不同地，配套不完全，區(qū)內(nèi)植被生長、土壤發(fā)育受到不同程度的制約。因缺水造成十分脆弱的生態(tài)系統(tǒng)。西南喀斯特山區(qū)，土層淺薄，多暴雨，容易發(fā)生泥石流、水土流失、土壤石漠化等生態(tài)問題和自然災(zāi)害；青藏高原寒冷嚴酷，空氣稀薄，氣候惡劣，植被荒疏，土地生產(chǎn)力低，地表植被一旦破壞很難恢復(fù)；黃土高原溝壑縱橫，土質(zhì)疏松，易于發(fā)生水土流失，是我國水土流失最嚴重的區(qū)域之一。我國東部自然條件較好，但面積小，降雨集中，極易產(chǎn)生旱澇災(zāi)害。
(2) Uncoordinated ecological process
Over the years, as a result of extensive pattern of economic and social development in China, the economies with a characteristic of high energy and resource consumption have achieved rapid development and the high arbitrariness in exploitation and utilization of water, soil and biological resources has led to potential impacts of a lot of uncertain factors on the material cycle, energy flow and information transmission of regional ecosystems, so that the ecological process may become incomplete and uncoordinated. At present, the most representative situation is that the improper development of hydropower and construction of water conservancy projects have made serious disturbances and damages on the river ecosystem. Damming has changed the flow patterns of rivers, shaped and intensified river fragmentation, changed hydrological characteristics and then changed the material field, energy field, chemical field of and biological field of the ecosystem, leading to changes in species structure, habitats distribution and corresponding ecological functions of the river ecosystem.
(3) Continually descending ecosystem functions
Structure damage and process disorder of regional ecosystem has brought about a continuous recession of ecosystem functions. The water conservation function of the source regions of great rivers has declined greatly; the functions of windbreak and sand fixation as well as soil and water conservation in the areas distributed with important natural vegetation have also declined continuously; with the shrinkage of wetland area, the flood regulation and storage function of wetland ecosystem has also declined; material production functions of grassland, forest and farmland ecosystems have declined too. The biodiversity maintenance function and climate regulation function of regional ecosystem have increasingly declined. Statistics show that the water supply volumes of the sources of several important rivers have reduced year after year. Compared with the 1990s and 1980s, the average annual flows of Yellow River, Yangtze River and Lancang River have decreased by 27%, 24% and 13% respectively. Both the quantity and area of lakes in Hubei Province have become 1/3 less than those in the 1950s; the area of the wetland of the Yangtze River through Nanjing has sharply reduced by over 3,000 ha within 15 years; the area of mangroves has dropped from 60,000 ha in the early post-Liberation period to less than 20,000 ha nowadays and reduction pace never slows down. The previous rich biodiversity of wetlands in the middle and lower reaches of the Yangtze River has declined significantly and the quantity of animal and plant resources has also decreased greatly, resulting in frequent floods. Massive loss of wetlands in three rivers source areas has led to storage reduction of fresh water and direct reduction of groundwater recharge, resulting in grassland degradation and desertification aggravation. And the corresponding situation is that in China, extremely severe sandstorms occurred for 8 times in the 1960s, 13 times in the 1970s, 14 times in the 1980s and over 20 times since the 1990s, involving wider and wider range and resulting in more and more serious loss.
II. Root Causes of Ecological Problems
1. Fragile ecological background
In spite of vast territory, distinct climatic differences, diverse topography types and complex geological conditions, on the whole, however, the background of China’s ecological environment is more fragile. The regions with fragile ecological environment such as arid or semi-arid regions, alpine regions, karst regions and Loess Plateau regions account for 60% of total land area of China.
The total area of northwestern regions occupies 1/3 of the land area of China, but water and heat resources are distributed in different regions and the matching is incomplete: alpine zones have plentiful precipitation but relatively lack heat; basin areas have rich heat resources but scarce precipitation; most parts of the northwest regions have a precipitation of 50~400 mm. Under these conditions, vegetation growth and soil development in these regions are subject to different constraints. Shortage of water resources has caused rather fragile ecosystems. Karst mountainous areas in southwest China have shallow soil and more rainstorms so that they are prone to landslides, soil erosion, soil desertification and other ecological problems and natural disasters; Qinghai-Tibet Plateau has harsh chilliness, thin air, bad weather, sparse vegetation and low land productivity so that its surface vegetation can hardly recover once damaged; Loess Plateau has crisscross gullies and loose soil so that it is susceptible to soil erosion, which is one of the regions with the most serious soil erosion in China. Eastern China has better natural conditions but encounters with droughts and floods easily owing to its small area and concentrated rainfall.
2013.4.12