This thesis intends to be a contribution both to the sociological analysis of law and to the analysis of regulatory approaches of biodiversity conservation. In particular, and on the one hand, I intend to contribute to a better understanding of the regulatory trilemma of ecosystems conservation in the context of the local implementation of the Convention on Biological Diversity (the ´CBD´). Specifically, I examine how local legal systems utilize traditional regulatory instruments, and particularly traditional property rights, in order to implement the ecosystems conservation -or in-situ conservation- measures of the CBD. On the other hand, I intend to develop an understanding of the reflexive or non-exclusionary nature of law, on the basis of the general theory of society of Niklas Luhmann. This will entail the development of an understanding of the reflexive form of law, which in turn will, first, allow us to go beyond the Weberian dichotomy between form and substance and, second, allow us to assess the varying degrees of social reflexivity –or reflexive capacity- of different legal forms. These theoretical developments will then be combined with Gunther Teubner´s post-regulatory approach known as reflexive law, which will allow us to explore general mechanisms for enhancing mutual observation and interference between law and society that, in turn, will be expressed on new forms of law that should have a higher reflexive capacity to tackle the limits of regulatory law. Furthermore, in the context of my analysis of reflexive law, I will propose an understanding of Teubner´s idea of interference –and of the encompassing idea of direct contact between law and society- by reference to Maturana´s and Hejl´s ideas on the relational and social domain, and to Bankowsky’s notion of transitional spaces, that should allow observing or better observing the interactions between law and different spheres of society. These theoretical understandings will allow me to better analyse the regulatory trilemma of ecosystems conservation and, particularly, better assess the limitations of the legal form of traditional property rights as a regulatory instrument for ecosystem´s conservation. This will show that these property rights are predominantly reflexive to the observations of the economic sphere but not to the observations of other social spheres. This analysis and critique will be mainly focused on ownership but, as will be shown, it will also apply to other traditional property rights such as easements and servitudes. Finally, it will be on the basis of all these understandings and considerations that I will propose and assess the creation of a new property right - the conservation property right- as a reflexive law mechanism that should allow broader social interaction amongst different spheres of society for the purpose of better tackling the regulatory trilemma of ecosystems conservation.