https://phys.org/news/2018-11-explore.html

In many fields, when researchers want to know whether something works they conduct an experiment. For example, patients are often randomly assigned to receive a new drug (or not) and the results are compared to determine if the new treatment has the potential to help people. Despite calls for more use of experiments in conservation, they remain extremely rare.

One common approach to conservation is encouraging owners to manage their land in a way which provides benefits for the environment. This has been done in the UK for decades. For example, farmers are paid to maintain hedgerows and leave stubble on fields to help farmland birds. These kinds of payments for ecosystem services schemes are increasingly used in the tropics as well.