This chapter addresses plant invasions in the protected areas of the Azores (Northern Atlantic), whose flora encompasses a considerable proportion of alien species (about 70 %). The chapter includes (i) a general characterization of the Azores, with particular reference to their Island Natural Parks covering 24 % of the inland surface; (ii) an assessment of the plant invasion status of the Island Natural Parks (based on distribution data and expert evaluation of potential impacts and possibility of control of invasive alien plants); and (iii) a report about on-going and recent management initiatives embracing the control of invasive alien plants. The results show that the Island Natural Parks of Santa Maria Island is potentially the most threatened by invasive alien plants, followed in decreasing order by the Island Natural Parks of the islands of Graciosa, São Jorge, Corvo, Faial, São Miguel, Terceira, Flores and Pico. Some of the most threatening species are highlighted. Due to the innovative assessment methodology, the results do not fully corroborate previous studies, showing that just species listing may not provide a full understanding of the potential effects of invasive alien plants on native biodiversity, thus bringing new insights that may assist management initiatives. Several invasive alien plants management projects run by the Azorean Government and the Portuguese Society for the Study of Birds are described, with reference to those supported by the LIFE programme and PRECEFIAS (an Azorean project devoted to control of invasive alien plants in protected areas). Finally, a holistic discussion is provided stressing strengths and weaknesses of all topics covered in the chapter so that more effective invasive alien plant management strategies can be achieved in the future.

Pittosporum undulatum Ventenat (Pittosporaceae) is a tree or shrub native to Australia introduced in the Azores Islands in the 19th century, presently naturalized in the nine islands. According to a random survey of vascular plants in the Azores, the invader is present throughout the archipelago, in 62% of 547 1-km2samples. It was found in pure or mixed stands, forming groups and also as isolated trees. P. undulatum was frequently found in native scrubland (62%), mixed woodland (39%) and hedgerows (25%). The altitudinal range extended from sea level up to about 800 m a.s.l., with the highest frequency between 100 and 400 m. The woody species more strongly associated with P. undulatum included characteristic native and endemic species as well as non-indigenous and invasive taxa. Based on a forest inventory, 49% of the forested area in the Azores, about 24,000 ha, is occupied by P. undulatum. Considerable areas inside Island Natural

Parks are covered by this species. The estimated annual P. undulatum biomass production in the Azores might range from only about 150 Mg in the small island of Corvo up to more than 60,000 Mg in Pico Island. The heating value of its wood and its chemical composition make it a good candidate for use in combustion or gasification processes. Since there are no resources available to control this large-scale invasion, using P. undulatum biomass for energy production might be an important factor to stimulate the progressive and sustainable cutting of its stands and its replacement by Macaronesian species.

Highlights► Pittosporum undulatum is the more important woody plant invader in the Azores. ► The invasion affects native scrubland and island natural parks. ► P. undulatum annual biomass production is high and of good quality. ► Biomass could cover a portion of electricity production in the Azores. ► This could allow the sustainable management and gradual replacement of P. undulatum.

Abbreviations DRRF, Regional Direction For Forest Resources (Forest Services);  EDA, Azores electricity;  GIS,Geographic Information System;  GPS, Global Positioning System;  INP, Island Natural Parks;  IUCN,International Union for Conservation of Nature;  SPSS, statistical package for the social sciences;  UTM,Universal Transverse Mercator