Recent volumes are available online in full-text at the Royal Botanic Gardens Kew, website: http://www.kew.org/ ; Diversity is a complex term that includes taxonomic, functional, spatial and temporal aspects of organisms variety. Conservation policies must be supported by holistic studies of ecosystem function, must aim to transform scientific knowledge into social responsibility creating a culture of respect towards nature and should also include economic components. Mediterranean ecosystems will likely experience the greatest proportional changes in biodiversity due to the substantial influence of land use and climate change as major drivers. Land use includes not only rural abandonment but also intensive exploitation of native forests (cork oak woodlands) or shrublands for animal or crop production. These last two are dependent on large Nitrogen (N) inputs. In this paper we intend to show the responses of Mediterranean ecosystems to increased N availability in terms of biodiversity and ecosystem functionality. We present two case studies: 1) a gradient of N availability due to a N point source; and 2) N manipulative field experiment (doses and forms). With these results our aim is to pinpoint the importance of improving scientific knowledge at a local level before we establish conservation policies at global level. The two case studies reflect a strong influence of the N source on ecosystem function. Finally, we use the SWOT (Strengths, Weakness, Opportunities and Threats) analysis approach to underpin the complexities of human intervention in the N cycle and the problem it poses for policies of plant conservation.