新托福TPO22阅读原文及译文：Spartina.docx

"v -Z-Z 新托福TPO22阅读原文(一):SpartinaTPO22-1: SpartinaSpartina alterniflora, known as cordgrass, is a deciduous, perennial flowering plant native to the Atlantic coast and the Gulf Coast of the United States. It is the dominant native species of the lower salt marshes along these coasts, where it grows in the intertidal zone (the area covered by water some parts of the day and exposed others).These natural salt marshes are among the most productive habitats in the marine environment. Nutrient-rich water is brought to the wetlands during each high tide, making a high rate of food production possible. As the seaweed and marsh grass leaves die, bacteria break down the plant material, and insects, small shrimplike organisms, fiddler crabs, and marsh snails eat the decaying plant tissue, digest it, and excrete wastes high in nutrients. Numerous insects occupy the marsh, feeding on living or dead cordgrass tissue, and redwing blackbirds, sparrows, rodents, rabbits, and deer feed directly on the cordgrass. Each tidal cycle carries plant material into the offshore water to be used by the subtidal organisms.Spartina is an exceedingly competitive plant. It spreads primarily by underground stems; colonies form when pieces of the root system or whole plants float into an area and take root or when seeds float into a suitable area and germinate. Spartina establishes itself on substrates ranging from sand and silt to gravel and cobble and is tolerant of salinities ranging from that of near freshwater (0.05 percent) to that of salt water (3.5 percent). Because they lack oxygen, marsh sediments are high in sulfides that are toxic to most plants. Spartina has the ability to take up sulfides and convert them to sulfate, a form of sulfur that the plant can use; this ability makes it easier for the grass to colonize marsh environments. Another adaptive advantage is Spartina’s ability to use carbon dioxide more efficiently than most otl plants.These characteristics make Spartina a valuable component of the estuaries where it occurs naturally. The plant functions as a stabilizer and a sediment trap and as anursery area for estuarine fish and shellfish. Once established, a stand of Spartina begins to trap sediment, changing the substrate elevation, and eventually the stand evolves into a high marsh system where Spartina is gradually displaced by higher-elevation, brackish-water species. As elevation increases, narrow, deep channels of water form throughout the marsh. Along the east coast Spartina is considered valuable for its ability to prevent erosion and marshland deterioration; it is also used for coastal restoration projects and the creation of new wetland sites.Spartina was transported to Washington State in packing materials for oysters transplanted from the east coast in 1894. Leaving its insect predators behind, the cordgrass has been spreading slowly and steadily along Washington’s tidal estuaries on the west coast, crowding out the native plants and drastically altering the landscape by trapping sediment. Spartina modifies tidal mudflats, turning them into high marshes inhospitable to the many fish and waterfowl that depend on the mudflats. It is already hampering the oyster harvest and the Dungeness crab fishery, and it interferes with the recreational use of beaches and waterfronts. Spartina has been transplanted to England and to New Zealand for land reclamation and shoreline stabilization. In New Zealand the plant has spread rapidly, changing mudflats with marshy fringes to extensive salt meadows and reducing the number and kinds of birds and animals that use the marsh.Efforts to control Spartina outside its natural environment have included burning, flooding, shading plants with black canvas or plastic, smothering the plants with dredged materials or clay, applying herbicide, and mowing repeatedly. Little success has been reported in New Zealand and England; Washington State’s management program has tried many of these methods and is presently using the herbicide glyphosphate to control its spread. Work has begun to determine the feasibility of using insects as biological controls, but effective biological controls are considered years away. Even with a massive effort, it is doubtful that complete eradication of Spartina from nonnative habitats is possible, for it has become an integral part of these shorelines and estuaries during the last 100 to 200 years.TPO22-1译文：米草属植物互花米草，俗称网茅，是一种落叶的多年生开花植物，原产自美国大西洋沿 岸和墨西哥湾地区。

它是这些海岸下游地区盐碱地的优势本地种，生长在潮间带(有时淹没在水中，有时暴露在空气中的区域)这些天然的盐碱地位于海洋环境下最肥沃的生境中涨潮时会给沼泽带来营 养丰富的海水，使得高产量成为可能随着海草和沼泽禾草叶子的死亡，细菌将 植物体分解，昆虫、小型虾状浮游生物、招潮蟹和沼泽蜗牛吃掉了腐烂的植物组 织，消化后排出富含营养的排泄物沼泽里生活着无数的昆虫，它们以活着或死 去的网茅组织为食，红翼歌鸫、麻雀、啮齿动物、兔子以及鹿都直接以网茅为食 每一个潮汐周期都会将植物带到近海海水中，它们可以被潮水下的生物所利用米草属植物是极具竞争力的植物它主要通过地下茎向四周扩展；当根系或 整株植物漂到一个地方扎了根，或者当种子漂到一个适合的地方发芽时，群落就 形成了从泥沙地到卵砾石地，米草属植物都能生长，其耐盐度在接近淡水(0.05%) 和盐水(3.5% )的范围内由于缺乏氧气，沼泽沉积物里的硫化物含量很高，，这 些硫化物对多数植物而言是有毒的米草属植物具有能够吸收硫化物并将其转换 成为硫酸盐(一种植物可以利用的硫形式)的能力；这种能力使得米草属植物更易。