Development of a standard monitoring protocol for assessing the impacts of REDD+ (Reduced Emissions from Deforestation and Degradation) projects on biodiversity is desirable. Drawing on the conservation literature and our personal experience, we review whether such a one-size-fits-all approach is justifiable on scientific and practical grounds. We conclude that achieving a model biodiversity monitoring protocol suitable for use in all potential REDD+ sites is probably an unrealistic objective, owing to the huge differences among the world's forests in terms of structure, species composition, ecological interactions and ecosystem services provided. Moreover, to provide useful feedback for conservation managers, ecological monitoring programmes must be designed around a project's conservation goals, which will vary from project to project, owing to these differences in forest ecology and human threats faced. Thus, site-specific biodiversity monitoring programmes are needed. No single monitoring method is likely to be optimal, or even suitable for use, in all REDD+ forests. Instead, we suggest that a standard approach be adopted, in which ecological monitoring research is (i) designed to reflect a project's biodiversity conservation goals; (ii) based upon scientifically-tractable, policy-relevant questions regarding the impacts of management interventions on the ecosystem; (iii) founded on detailed knowledge of the habitat type in question; (iv) includes monitoring of a number of indicators, as appropriate to the project; and (v) defines appropriate reference/baseline conditions against which progress can be assessed.
