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濫伐森林、過度放牧 南美上億頃土地劣化
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本報2016年6月21日綜合外電報導，姜唯編譯；蔡麗伶審校
世界糧農組織（FAO）指出，全球有95%的糧食來自土壤，但全球已有33%的土地劣化。在整個南美洲，有超過68%的土地受到侵蝕——高達1億公頃的土地因森林砍伐而劣化，7000萬公頃土地過度放牧。
森林砍伐容易導致土壤劣化。圖片來源：CIFOR（CC BY-NC-ND 2.0）
國土沙漠化 成南美糧食危機
在拉丁美洲和加勒比海地區，阻止土壤劣化是維持生態永續和糧食安全的重要措施。像巴西東北部，160萬平方公里土地沙漠化，佔國土面積18%，大幅影響玉米和豆類等主食作物生產。
在阿根廷、墨西哥和巴拉圭，超過一半國土出現土壤劣化和沙漠化問題。玻利維亞、智利、厄瓜多和秘魯則有27%至43%的國土面臨沙漠化。
玻利維亞問題尤其嚴重，超過600萬人，也就是77%的居民住在劣化地區。中美洲也不遑多讓。根據2014年EUROCLIMA區域合作計畫繪製的拉美和加勒比海土壤輿圖，薩爾瓦多75%的土地遭侵蝕，瓜地馬拉12%的土地面臨沙漠化威脅。
在非洲，80%的土地被中度至重度侵蝕，10%的土地出現輕度侵蝕。
為提醒全世界土壤沙漠化和劣化的嚴重性，聯合國將6月17日訂為「國際對抗沙漠化與乾旱日」，今年的主題是「保護地球，重建土地，全民參與」。
土壤劣化影響貧戶 增加族群衝突機會
FAO區域辦公室Pilar Román說，貧窮、土地沙漠化和劣化之間有高度的相關性：「眾多研究顯示，最貧窮脆弱的社群所能獲得的資源最少。貧窮社群沒有肥沃的土地、缺少種籽、水源、生產資源、農業機具和獎勵。在這些貧窮社群中，最脆弱的是女性和原住民。貧窮與土壤問題互為因果：土壤劣化迫使社群遷徙，產生衝突。」
其中一個例子是智利。當地有49%的土壤中度至重度侵蝕，62%沙漠化。
當地政府為規劃和執行氣候變遷策略性遷移和適應措施，以過去60年的氣象和生物氣候資料加上自然地理、社會經濟和環境指標，以及自然資源統計數據，製作最新土壤劣化地圖。
這份地圖的作者、Sud-Austral顧問公司專家杜阿爾特（Efraín Duarte）指出，全國性土地沙漠化、劣化和乾旱的直接原因是森林砍伐、森林劣化、森林大火、土地利用方式改變以及氣候變遷，間接原因則有植被監督、管理和栽種不當，加上偏鄉貧窮、知識水準低以及不重視植物資源的風氣。
政府以這份地圖為基礎，設計了復育和保護原始森林、沙漠植物和重建森林植被的國家計畫。杜阿爾特表示，對抗沙漠化是國家和國際社會的共同責任。
Román同意他的看法，並表示預防土壤劣化的工作應根據適當資訊、訓練，喚起社群與決策者對保護土壤的問題意識。此外，也應避免短視近利的農法給予土地壓力。
Soil Degradation Threatens Nutrition in Latin America
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This article is published ahead of the World Day to Combat Desertification, celebrated Jun. 17.
Las Canoas Lake in the town of Tipitapa, near Managua, dries up every time the El Niño weather phenomenon affects Nicaragua, leaving local residents without fish and without water for their crops. Credit: Guillermo Flores/IPS
- Curbing soil degradation is essential for ecological sustainability and food security in Latin America and the Caribbean.
“Everyone knows how important water is, but not everyone understands that soil is not just what we walk on, it’s what provides us with food, fiber and building materials, and it is where water is retained and atmospheric carbon is stored,” said Pilar Román at the regional office of the United Nation Food and Agriculture Organisation (FAO).
More than 68 percent of the soil in South America is currently affected by erosion: 100 million hectares of land have been degraded as a result of deforestation and 70 million have been over-grazed.
For example, desertification plagues 55 percent of Brazil’s Northeast region – whose nearly 1.6 million sq km represent 18 percent of the national territory – affecting a large part of the staple food crops, such as maize and beans.
In Argentina, Mexico and Paraguay, over half of the territory suffers problems linked to degradation and desertification. And in Bolivia, Chile, Ecuador and Peru, between 27 and 43 percent of the territory faces desertification.
An especially serious case is Bolivia, where six million people, or 77 percent of the population, live in degraded areas.
The situation is not much different in Central America. According to the 2014 Soil Atlas of Latin America and the Caribbean produced by the EUROCLIMA program, erosion affects 75 percent of the land in El Salvador, while in Guatemala 12 percent is threatened by desertification.
FAO stresses that as much as 95 percent of the food consumed worldwide comes from the soil, and 33 percent of global soils are degraded.
In Africa, 80 percent of land is moderately to severely eroded, and another 10 percent suffers from slight erosion.
To alert the global population about the dangers posed by desertification and soil degradation, the world celebrates the World Day to Combat Desertification on Jun. 17, under the theme this year of “Protect Earth. Restore Land. Engage People”.
“Without a long-term solution, desertification and land degradation will not only affect food supply but lead to increased migration and threaten the stability of many nations and regions,” U.N. Secretary General Ban Ki-moon said on the occasion of the international day this year.
Román, with the FAO regional office’s technical support for South American subregional coordination, told IPS that there are close links between poverty, desertification and land degradation.
“Numerous studies show that the poorest and most vulnerable communities have the worst access to inputs. A poor community has access to less fertile land, and more limited access to seeds, water, productive resources, agricultural machinery and incentives,” she said.
Terraces built by Atacameño indigenous people in the village of Caspana, in the northern Chilean region of Antofagasta. This age-old farming technique represents local adaptation to the climate and arid soil to guarantee the food supply for Andean highlands people. Credit: Marianela Jarroud/IPS
“In these poor communities, the most vulnerable are women, who have fewer land titles and more restricted access to economic incentives, and indigenous people.
“There is a direct correlation in that direction and vice versa: degraded soil will push a community to migrate and will generate conflicts over a limited resource,” she said in an interview in the FAO regional office in Santiago.
One example is Chile, where 49 percent of the land suffers from moderate to severe erosion and 62 percent faces desertification.
To address this severe problem, the authorities updated a land degradation map, with the aim of designing and implementing strategic climate change mitigation and adaptation measures.
The map was updated using meteorological and bioclimatic data from the last 60 years, as well as physiographical, socioeconomic and environmental indicators, and statistics on natural resources.
Efraín Duarte, an expert with Sud-Austral, a private consultancy, who is the author of the updated map, told IPS that “the main direct causes of desertification, land degradation and drought at a national level are deforestation, degradation of forests, forest fires and processes arising from land-use changes.”
“The impact of climate change” should also be factored in, he said.
According to several studies, at least 25 percent of the rainfall shortage during the current drought in Chile, which has dragged on for nearly five years, is attributable to human-induced climate change, said Duarte.
He also cited indirect causes: “Inadequate public policies for oversight, regularisation and fomenting of ‘vegetational’ resources (forests, bushes and undergrowth), combined with rural poverty, low levels of knowledge, and a lack of societal appreciation of plant resources.”
Using the updated map, the government designed a national strategy focused on supporting the recovery and protection of native forests and plants adapted to desert conditions, and on fomenting reforestation and revegetation.
According to Duarte, “Chile could carry out early mitigation actions focused on fighting deforestation, forest degradation, excessive extraction of forest products, forest fires, over-grazing, over-use of land and unsustainable land use, and lastly, the employment of technologies inappropriate for fragile ecosystems.”
The expert said the fight against desertification is a shared responsibility at the national and international levels.
Román concurred and proposed that the prevention of soil degradation should be carried out “in a holistic manner, based on adequate information and training and awareness-raising among communities and decision-making agents on protection of the soil.”
Also important in this effort are agricultural production, avoiding the use of bad practices that prioritise short-term results, and pressure on land, he added.
For FAO, sustainable agricultural production practices would make it possible to produce 58 percent more food, besides protecting the soil for future generations.
Prevention not only consists of applying techniques in the countryside, but also making efforts at the level of government and legal instruments, and working with the communities, said Román.
While the ideal is to prevent degradation and desertification, there have been successful initiatives in the recovery of desertified areas.
In Costa Rica, for example, the two main causes of degradation were reduced between 1990 and 2000, when the area affected by deforestation shrank from 22,000 to 8,000 hectares, while the area affected by forest fires shrank from 7,103 to 1,322 hectares.
Román underlined that, as a form of mitigation, it is important to diversify and expand the range of foods consumed, as potatoes, rice, wheat and maize – just four of the 30,000 edible plants that have been identified – currently represent 60 percent of all food that is eaten.
“On one hand, monoculture plantations of these plants are one of the factors of soil degradation, and on the other hand, a diet based on carbohydrates from these plants generates malnutrition,” she said.
Edited by Estrella Gutierrez/Translated by Stephanie Wildes
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