A large number of schemes exist around the world to conserve or establish target natural vegetation communities. These include voluntary agri-environmental contracts, which aim to establish a target vegetation community by compensating farmers to reduce stocking rates. These contracts initiate a stochastic vegetation succession which increases the probability of establishing the target vegetation community. To ensure the scheme is achieving its objectives, regulators monitor the vegetation succession and decide whether a contract should stop or continue. If vegetation succession can be represented by a Markov chain, the regulator's problem of when to monitor, the best monitoring method and when to stop or continue a contract can be solved by a partially observed Markov decision process (POMDP). The results, for the conservation and restoration of heather Moorland in the Cambrian Mountains of Wales, show that the frequency and quality of monitoring depends upon monitoring costs and the regulators prior probabilities for the vegetation state. (c) 2005 Elsevier B.V. All fights reserved.