What steps should be taken by the Government in order to conserve flora and fauna?

Better to ask should fauna and flora be conserved? after all, before there were humans there were wholly natural m extinctions. So why should we play god and decide what species should be protected? There are many examples where attempts in the past to create special situations to protect a species or environment have proved detrimental. The National Trust recently published some info about this but i havent been able to find the reference.