气温升高使北美野牛体型变小

海量资料下载 免费学习英语 www.englishvip.com/xinlw.htm （申请网址） As temperatures go up, bison get smaller. Joseph Craine, research assistant professor in the Division of Biology at Kansas State University, examined how climate change during the next 50 years will affect grazing（放牧） animals such as bison and cattle in the Great Plains. The study, "Long-term climate sensitivity of grazer performance: a cross-site study," was recently published in the peer-reviewed scientific journal PLOS ONE.   "Bison are one of our most important conservation animals and hold a unique role in grasslands in North America," Craine said. "In addition to their cultural and ecological significance, they're economically important both from a livestock perspective and from a tourism perspective. There are about half a million bison in the world."   Craine analyzed a data set of 290,000 weights, ages and sexes collected from 22 bison herds throughout the U.S. The information came from herds owned by the university's Konza Prairie Biological Station; Oklahoma's Nature Conservancy; Turner Enterprises; and other federal, state, nonprofit and commercial entities. The organizations kept annual records of each animal in the herd and matched the data with the climates of the sites.   Based on differences in sizes of bison across herds, Craine found that during the next 50 years, future generations of bison will be smaller in size and weigh less. Climate is likely to reduce the nutritional quality of grasses, causing the animals to grow more slowly.   "We know that temperatures are going to go up," Craine said. "We also know that warmer grasslands have grasses with less protein, and we now know that warmer grasslands have smaller grazers. It all lines up to suggest that climate change will cause grasses to have less protein and cause grazers to gain less weight in the future."   Craine said the results of climate change in coming decades can already be seen by comparing bison in cooler, wetter regions with those in warmer, drier regions. For example, the average 7-year-old male bison in South Dakota weighed 1,900 pounds, while an average 7-year-old male bison in Oklahoma -- a warmer region -- weighed 1,300 pounds. The cause: grasses in the southern Great Plains have less protein than grasses in the northern Great Plains because of the warmer climate.   "The difference in temperature between those two states is around 20 degrees Fahrenheit, which is about three times the projected increase in temperatures over the next 75 years," Craine said. "That's a pretty extreme difference and beyond the worst-case scenario. But it is a clear indicator that long-term warming will affect bison and is something that will happen across the U.S. over the next 50-75 years." 随着气温上去了，野牛变得越来越小。约瑟夫Craine，在堪萨斯州立大学生物学部研究助理教授，研究如何在未来50年的气候变化将影响放牧放牧动物如野牛和牛在大平原。这项研究，“长期气候敏感性的食草动物的性能：跨站点研究”，最近发在同行评议的科学期刊PLoS ONE。   “野牛是我们最重要的保护动物之一，在北美草原上举行了独特的作用，Craine说。” “除了他们的文化和生态意义，他们无论是从经济上重要的家畜的角度来看，从旅游的角度，有在世界上约50万野牛”。   Craine分析的290,000重量，年龄和性别从22野牛牛群在美国各地大学的孔扎草原生物站俄克拉何马州的自然保护协会;特纳企业;和其他联邦，州，拥有从牛群的信息收集一个数据非营利性和商业的实体。该组织每年保持在牛群和记录每个动物相匹配的站点的气候数据。   基于野牛整个牛群的大小差异，Craine发现，在未来的50年中，野牛的后代将是规模较小的重量更轻。气候可能降低草的营养质量，导致动物生长比较缓慢。   Craine说：“我们知道，温度要涨，”。“我们也知道，温暖的草原草蛋白质少，我们现在知道，温暖的草原上有较小的食草动物，它的所有行表明，气候变化将导致草较少的蛋白质和导致食草动物获得的重量在未来少“。   Craine说在未来几十年气候变化的结果已经可以看出通过比较凉爽，潮湿的地区，在温暖，干燥的地区的野牛。例如，在南达科他州的平均7岁的雄性野牛重达1,900磅，而在俄克拉何马州的平均7岁的雄性野牛 - 一个温暖的地区 - 重达1300磅。原因：在大平原南部的草比草北部大平原，因为气候变暖有较少的蛋白质。   “这两个状态之间的温度差大约是华氏20度，这是预计在未来75年以上的温度增加的三倍左右，Craine所述。“这是一个非常极端的差异超出了最坏的情况。但它是一个明确的指标，长期变暖将影响野牛的东西，将在未来50-75年发生在美国各地。” “成千上万人疯狂下载。。。。。。 更多价值连城的绝密英语学习资料， 洛基内部秘密英语，技巧，策略 请在 网上 申请报名” 洛基国际英语 竭诚为您服务