Divergent occurrences of juvenile and adult trees are explained by both environmental change and ontogenetic effects

• DOI: 10.1111/ecog.06042
• Publication Date: 2022-01-27T08:51:25Z
• Authors: Lukas Heiland; Georges Kunstler; Paloma Ruiz‐Benito; Allan Buras; Jonas Dahlgren; Lisa Hülsmann
• Keywords: Environmental change; Divergence (linguistics); Environmental gradient

Recent climate warming has fueled interest into climate‐driven range shifts of tree species. A common approach to detect is compare the divergent occurrences between juvenile and adult trees along environmental gradients using static data. Divergent life stages can, however, also be caused by ontogenetic effects. These include viable conditions throughout development (‘ontogenetic niche shift') as well demographic dependencies that constrain possible occurrence subsequent stages. Whether effects are an important driver large‐scale climatic largely unknown. It is, critical in evaluating whether impacts change can inferred from data on stage occurrences. Here, we first show theoretically, a two‐life simulation model, how both temporal shift lead similar adults juveniles (juvenile divergence). We further demonstrate divergence unambiguously attributed effects, when diverge opposite direction their gradient. Second, empirically test across Europe, use repeated national forest inventories Sweden, Germany Spain assess for 40 species gradients. About half species‐country combinations had significant divergences heat sum water availability Only quarter detectable within observation period. Furthermore, were frequently associated with shifts, indicating relevant cause Our study furthers understanding challenges practice inferring