Resilience of alder in response to global change stressors

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Publication . Marques, Inês Catarina Gomes; González, Patricia María Rodríguez; David, Teresa Soares; Solla Hach, Alejandro; Garbelotto, Matteo

Alders (Alnus spp.) are riparian tree species frequently used in restoration actions due to their contribution to the health of fluvial ecosystems and to their pioneer role in ecological succession. Alder decline induced by global change stressors such as heat, drought and invasive pathogens, including Phytophthora spp., intensifies the need for a better understanding of alder resilience, which in turn inform best management practices in riparian corridors. Additionally, the recent taxonomic differentiation between the pan-European Alnus glutinosa and the Iberian-North African A. lusitanica prompts for the investigation of traits and responses to decline that differentiate both species. This thesis aims to (1) assess the genotypic and phenotypic variation in A. glutinosa and A. lusitanica populations across their latitudinal range (from Northern Africa to Scandinavia), (2) assess alders’ resilience to individual and combined abiotic and biotic stressors and (3) supply a tool for managers and stakeholders to support ecosystem management decisions in riparian corridors experiencing alder decline. This thesis identified morphological and biochemical differences between A. glutinosa and A. lusitanica. The southern populations of A. lusitanica showed higher genetic diversity than A. glutinosa populations and possibly adaptation advantages to lower water availability and heat. Alders’ response to the combination of drought or heat with Phytophthora spp. was dependent on species, genetic groups and ecological preferences. The decision-support tool ADnet pinpointed some key factors favouring Phytophthora alni survival and determining disease incidence, based on expert knowledge from several scientific backgrounds, bibliographic information and an original dataset. First and foremost, this thesis contributes new knowledge regarding the restoration and management of riparian corridors by supplying a screening of specific alder traits and genetic groups possibly correlated with adaptation potential to abiotic and biotic stressors. Additionally, it provides a tool to support management decisions and knowledge transfer to specifically address P. ×alni-induced alder decline.

2024-11-20Doctoral thesis

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