They found that protection reduced deforestation: approximately 10% of the PAs would have been deforested had they not been protected. In contrast, the conventional approaches to evaluation overestimated avoided deforestation by over 65%. Three other studies of certification schemes also found positive impact, whereas one (Villalobos et al. A similar result holds for Protected Area extent, suggesting possible displacement of deforestation from PAs (i.e. leakage). Laycock et al (2009) estimated the cost-effectiveness of the UK Biodiversity Action Plan. The present value cost of implementing the 44 Species Action Plans for w'hich cost data w'ere available over the 10-year period in question varied from GBP 500 to GBP 7,000,000.