[Carry_Okie]

Sheep are more efficient with grasses. They destroy 98% of the seed.

You are forgetting that the bigger the environmental problem is, the bigger will be the budget to "fix" it (which, of course, never happens).

[Ernest_at_the_Beach]

The invader grass grows by cloning, spreading roots that form circular duplicates of the original colony. The clones clone, creating an ever-rising growth curve.

"What it looks like is an accelerating rate of invasion," UC Davis researcher Debra Ayres said. "Instead of exponential growth, we have greater than exponential growth."

I am searching my math handbooks for Greater than Exponential Growth

Have we every seen this before in Biological Organisms?

Found this site:

mathematical epidemiology information

[bedolido]

Sheep are more efficient with grasses. They destroy 98% of the seed.

There are obvious reasons why sheep cannot be used in the San Francisco area.