Distribution and natural establishment of Eucalyptus globulus in the Iberian Peninsula: insights into processes affecting plant establishment

Abstract

Eucalypt plantations expanded across many countries and became subject to controversy, particularly about their ecological impacts and invasive potential. The same is true in the Iberian Peninsula (Iberia) regarding Eucalyptus globulus Labill. This thesis is composed by six studies (chapters) tackling poorly explored aspects in these domains, with the following objectives: a) to evaluate potential future dynamics of E. globulus plantations in Iberia according to different climate change scenarios and possible conflicts with high biodiversity areas (Chapter 1); b) to explore the influence of different factors on the natural establishment of E. globulus (Chapters 2-5); c) to perform a review of the literature investigating the natural establishment of eucalypt species (Chapter 6). In Iberia, under both climatic scenarios, the suitable range of E. globulus plantations is expected to shrink and conflicts with high biodiversity areas may aggravate (Chapter 1). A countrywide survey in Portugal to estimate E. globulus recruitment, using Google Street View, showed that recruitment is mostly influenced by climatic variables (annual precipitation and thermal amplitude) and that Google Street View is a cost-efficient alternative to car surveys (Chapter 2). Field surveys in E. globulus plantations in Central Portugal showed abundant recruitment along plantation edges, influenced by local factors such as soil cover and tree age. Wildlings, mostly adult, are spread up to 76 meters from plantations (Chapter 3). A sowing experiment using E. globulus seeds showed that germination and survival was enhanced after harrowing (Chapter 4). A seed predation experiment revealed that E. globulus seeds are highly attractive but they have escaped in many locations (Chapter 5). The literature review retrieved 37 studies, addressing 61 eucalypt species in seven countries. Key factors influencing eucalypt recruitment include fire, propagule pressure and disturbances (Chapter 6)