the tricky part is that the underlying problem is the drastic decrease in keystone species that are responsible for habitat maintinence/engineering, famously beavers and bison in certain areas, but they are only part of the equation. In other areas horses are responsible for primary environmental maintanence, where in the north, there incesant hunting for food tramples the ground ,compacts the snow, and actualy creates permafrost as a result, and in deserts horses are prodigious well diggers, and will dig down into dry river beds till they hit sub surface flow more than 10 ' down, which then all the other critters will use. As to seed dispersal, there are so many relationships between plants and animals that it's never endingly facinating to marvel at just how long and strange the processes must be to achive such specialised forms and methods. All in all humanity is playing a very dangerous game by treating everything in nature as worthless and expendable, or cute, and great for backgrounding a selfie and therefor about them.