On average how much energy is passed from one trophic level to the next

After a recent rainy season, a number of the communities in a western state suffered flooding and mudslides. a study commissioned by the state legislature determined that the extensive removal of a certain plant from hillsides within the state contributed significantly to the flooding and mudslides. the plant had an extensive root system that hold hillside soil in place, and it was being rapidly removed because its roots had recently gained national favor as a powerful herbal remedy. as a result, the legislature passed a statute prohibiting the removal of more than 50% of such plants from any hillside within the state. a landowner within the state challenged the statute under the takings clause of the fifth amendment, alleging that he had regularly harvested substantially more than 50% of the plants from his property and needed to do the same this year to meet the demand for the root. is he likely to prevail in his challenge?