Delineating limits: Confronting predicted climatic suitability to field performance in mistletoe populations

• Published in: The Journal of ecology 2018-11, Vol.106 (6), p.2218-2229
• Main Authors: Sangüesa-Barreda, Gabriel, Camarero, J. Julio, Pironon, Samuel, Gazol, Antonio, Peguero-Pina, José Javier, Gil-Pelegrín, Eustaquio
• Format: Article
• Language: English
• Subjects: Climate models; Climatic conditions; Climatic data; Cold; Cold tolerance; Demographic variables; Demographics; Distribution; Drought; Drought resistance; Ecophysiology; Environmental assessment; establishment; Fitness; Forests; Germination; hemiparasitic plant; Interactions; Photoinhibition; Pine; Plant-climate interactions; Seed germination; Seedlings; Seeds; Species; Species Distribution Models; Translocation; Trees; Viscum album; water‐use efficiency
• ISSN: 0022-0477; 1365-2745
• DOI: 10.1111/1365-2745.12968

1. Biotic stressors such as hemiparasites have a profound impact on forest functioning. However, predicting the future incidence of these stressors on forests remains challenging because climate-based distribution does not consider tree-hemiparasite interactions or the impacts of extreme climate events on stressors' performance. 2. We use species distribution models (SDMs) and ecophysiological and demographic field data to assess whether climatic suitability is a proxy for the performance of the hemiparasite mistletoe (Viscum album) in two forests with contrasting climatic conditions. Two host tree species representing wet-cold (Scots pine) and drywarm (Aleppo pine) conditions were selected. We fitted SDMs based on climate variables, and measured different ecophysiological variables capturing cold- (photoinhibition) and drought tolerance (intrinsic water-use efficiency, iWUE). We also assessed demographic variables related to seed germination and establishment rates of mistletoe through a translocation experiment. 3. Species distribution models showed a high climatic suitability of mistletoe in both forests. Mistletoes living in the Scots pines site presented a higher cold tolerance, while those inhabiting the Aleppo pine site showed a higher iWUE. Seedlings coming from local seeds showed a lower mortality than seedlings coming from translocated seeds. Germination and seedling establishment showed temporal mismatches when comparing local and translocated seeds. 4. Synthesis. Habitat suitability predicted by SDMs based on climate data and field performance were related in this mistletoe species. However, ecophysiological and demographic variables indicated a lower fitness of mistletoe in the drywarm site associated with drought stress. In conclusion, predicted climate suitability based on SDMs forecasts should be refined using field data on actual performance and considering plant-to-plant interactions and extreme climate events.