研究发现，黄石公园的野牛会自己割草，并给自己的食物施肥

A study of grazing in Yellowstone National Park found that bison essentially mow and fertilize their own food. This allows them to graze in one area for two to three months during the spring and summer while other hoofed mammals must keep migrating to higher elevations to follow new plant growth.

一项在黄石国家公园放牧的研究发现，野牛基本上是自己割草并施肥。这使得它们可以在春季和夏季在一个地区吃上两到三个月的草，而其他有蹄哺乳动物必须不断迁移到更高的海拔去追随新的植物生长。

Hundreds of bison grazing in an area stimulates the growth of nutritious grasses, in part because their waste acts as a fertilizer, according to research published this week in the Proceedings of the National Academy of Sciences.

本周发表在《美国国家科学院院刊》(Proceedings of the National Academy of Sciences)杂志上的一项研究称，在一个地区放牧的数百头野牛会刺激营养草的生长，部分原因是它们的粪便可以充当肥料。

“They add fertilizer through urinating and defecating, they drop nutrients back on the landscape, which are then available to plants,” Yellowstone scientist Chris Geremia said Wednesday.

黄石公园的科学家克里斯·格米亚于本周三说:“它们通过排便和撒尿来施肥，然后把养分撒回地面，供植物利用。”

“It’s almost like the bison become this giant fleet of lawnmowers moving back and forth across the landscape,” he said.

他说:“这就像野牛变成了庞大的割草机舰队，在陆地上来回移动。”

When more bison grazed an area more intensely, the area greened up earlier and faster and the grass stayed greener and had a higher nutritional quality for a much longer time, Geremia said.

Geremia说，当更多的野牛在更密集的地区吃草时，该地区会更早、更快地变绿，草也会更绿，而且在更长的时间内具有更高的营养价值。

Many other migratory animals in Yellowstone — pronghorn, bighorn sheep, mule deer and elk — do not form these large groups while they migrate and graze, Geremia said.

Geremia说，黄石公园的许多其他迁徙动物，如叉角羚、大角羊、骡鹿和麋鹿，在迁徙和放牧时并没有形成这些大群体。

“Bison don’t just move to find food, kind of the classic way that we think of animal migration,” Geremia said, “but they create good food by how they move and how they graze.”

“野牛不只是移动来寻找食物，这是我们认为动物迁徙的一种典型方式，”Geremia说，“它们通过移动和放牧的方式来创造优质食物。”

From 2012 to 2017, researchers fenced off plots of grass along bison migration corridors and compared them to the grazed areas.

从2012年到2017年，研究人员沿着野牛迁徙走廊隔离了一小块草地，并将它们与放牧地区进行了比较。

“The data showed that grasses heavily grazed by bison were more productive compared to exclosures where bison were not allowed to graze,” said Matthew Kauffman, unit leader of the US Geological Survey’s Wyoming Cooperative Fish and Wildlife Research Unit at the University of Wyoming. “The mowed-down forage had higher ratios of nitrogen to carbon, a standard measure of nutritional quality.”

美国地质调查局怀俄明鱼类与野生动物合作研究小组组长马修·考夫曼说:“数据显示，与不允许野牛放牧的禁猎区相比，那些被野牛大量放牧的草地产量更高。”“经过刈割的饲料具有更高的氮碳比，这是衡量营养质量的标准指标。”

Trampling and nibbling by the bison kept the plants shorter and denser and forced the plants to keep growing, giving the bison a steady supply of fresh, nutritious grass.

野牛的践踏和啃咬使植物变得更短、更密，并迫使植物继续生长，给野牛提供了稳定的新鲜、有营养的草。