Farming
Humans are developing open areas for farming or urban developement. When grasslands are converted into cropland, it reduces the food source for many wild animals. This could lead to migration or starvation of the animals.
Hunting
The american bison population was devastated by earopean settlers and almost became extinct due to overhunting for the fur and meat. Elephants are and endangered animal due to hunting for their tusks, which make ivory.
Positive Impacts
Some people do their part to preserve the land and restore it. National parks have been developed around grasslands. Governments have also enacted laws against hunting of endangered animals. Today, only about 1% of grasslands is officially protected but governments are now more aware of this issue.