Disentangling the climatic and biotic factors driving changes in the dynamics of Quercus suber populations across the species‘ latitudinal range

Abstract

Aim Impacts of different global change drivers are altering the performance of plant species worldwide. However, these pressures usually differ across the species' distribution range. To properly assess the combined effect of global change at species level, we need to evaluate its consequences across their complete distribution. We focused on recent decline in Cork oak (Quercus suber L.) populations given its high ecological and economic relevance. Location We selected 10 different sites (and two populations per site) separated about one degree in latitude across the core distribution of Q. suber, following a transcontinental aridity gradient. Methods To evaluate the current trends in population dynamics across the species' distribution and the factors implied on population decline, we evaluated the effect of latitude, aridity, pathogens (Phytophthora cinnamomi), stand density and tree size on seed and crop size, demographic structure, dominance of recruitment bank, defoliation and mortality. Results We found an increase in seed weight as latitude decreased, with a homogeneous low crop size across the complete distribution. Demographic structure was determined by latitude, precipitation and pathogen abundance. We detected a trend towards reduced sapling densities towards the southern edge of the distribution, with a demographic structure dominated by old trees. The low sapling density at the southern edge translates into a loss of dominance with respect to other woody species, suggesting an alteration of community structure in the mid‐term future. Tree density, precipitation and pathogen abundance determined tree mortality across the species distribution, with a higher abundance of pathogens in central‐latitude populations. Main conclusions Our results allow the early detection of declining trends and the evaluation of the main risks for species' conservation, suggesting potential for range displacement of the species driven by the recruitment failure at the southern edge of the distribution and a likely range expansion at northern populations.

Shifts in Growth Responses to Climate and Exceeded Drought-Vulnerability Thresholds Characterize Dieback in Two Mediterranean Deciduous Oaks

“…This approach allows identifying early-warning signals of growth shifts to long-term warmer and drier conditions. Although we used a process-based growth model and did not consider other demographic process, which should be included to model forest dynamics (regeneration, reproduction, mortality rates; see for instance [73,74]), our approach provides robust results in agreement with what has been observed in other analyses of oak dieback [2,5,14,15,54,61,75].…”

Chemical variations in Quercus pollen as a tool for taxonomic identification: Implications for long‐term ecological and biogeographical research

“…Both are indifferent towards bedrock conditions, but prefer soils without waterlogging, although Q. coccifera is a thermophilous species and is less tolerant of winter cold. is distributed across the Mediterranean Basin on siliceous bedrock but is absent from areas with winter cold(Amigo, 2017;Matías, Abdelaziz, Godoy, & Gómez-Aparicio, 2019).…”

What's hot in conservation biogeography in a changing climate? Going beyond species range dynamics

“…At the species level, dedicated sampling along longitudinal sites can help determine species’ early warning signs of decline. In this issue, Matías, Abdelaziz, Godoy, and Gómez‐Aparicio () shows how different biotic and abiotic factors can shift within the tree species Quercus suber —an economically important tree species in the Iberian Peninsula. Understanding such demography variations to detect within‐species’ decline may better help connect conservation biogeography with local management applications.…”

“…At the species level, dedicated sampling along longitudinal sites can help determine species' early warning signs of decline. In this issue, Matías, Abdelaziz, Godoy, and Gómez-Aparicio (2019) shows how different biotic and abiotic factors can shift within the tree species Quercus suber-an economically important tree species in the Iberian Peninsula.…”