I am looking for case studies that provide lessons learned or successful outcomes (in conservation/environment) that have used interdisciplinary/transdisciplinary approaches.
The USForest Service uses this approach in evaluating most activities and decisions. I have an EIS conerning Loblolly pine removal and a regional guide on soil and water conservation practices on researchgate site that explains the interdisiplinary planning and analysis process typically used to supply information for informed decisions. Perhaps useful for you.
Guimarães, M. H., McKee, A., Lima, M. L., Vasconcelos, L., Boski, T., & Dentinho, T. (2015). Putting transdisciplinarity into practice: a mixed mode procedure for stakeholder participation in natural resource management. Journal of Environmental Planning and Management, 58(10), 1827-1852.
Mckee, A., Guimaraes, M. H., & Pinto-Correia, T. (2015). Social capital accumulation and the role of the researcher: an example of a transdisciplinary visioning process for the future of agriculture in Europe. Environmental Science & Policy, 50, 88-99.
Guimarães, M. H., Ballé-Béganton, J., Bailly, D., Newton, A., Boski, T., & Dentinho, T. (2013). Transdisciplinary conceptual modeling of a social-ecological system—A case study application in Terceira Island, Azores. Ecosystem Services, 3, e22-e31.
You may look for various case studies reported and published on biological reclamation of waste dumps in surface mines. They present good interdisciplinary and trans-disciplinary approach combining the knowledge of mining engineering, geo-technical engineering, soil mechanics, plant and animal sciences.
An additional comments, the attached article is a case study on natural resources conversation and eco-social resilience to natural disasters from an agroecological experience in Central America during the Hurricane Mitch.
Yes. If you visit United Nations (UN) agencies website on your topic of interests, you will find several examples. You can explore of your own country if there are in the UN repository. UNEP and UNDP may be of good sources.