A Resource Centric View of Climate and Mast Seeding in Trees

Abstract

Seed production by trees has consequences for regeneration, nutrient cycling, trophic interactions, invasive species impacts and various diseases influencing human health. Effective management of these consequences requires a mechanistic understanding of tree seeding patterns. It has long been known that inter-annual variability and synchrony in seed production relate to among year differences in climate. A central question to resolve is whether such seeding patterns relate to climate-driven resource dynamics. To answer this question, we first assess the role of resources (emphasising mineral nutrients and carbohydrates) during the reproductive cycle. We conclude that trees not only utilise remobilised resources stored at the beginning of a reproductive cycle but also resources taken up and recycled subsequently. Secondly, we consider resource dynamics in relation to climate-driven processes. A sequence of climate-resource relationships potentially influences the maximum seed production set at initiation as well as the level to which this maximum is achieved throughout the rest of the reproductive cycle. Thirdly, climate-resource relationships are used to appraise the assumptions of resource-based models commonly employed to enhance our understanding of tree seeding. We conclude that these models need to accommodate a wider set of processes including resource uptake and interrelationships among multiple resources throughout the reproductive cycle. Finally, we consider how climate-driven resource dynamics may have facilitated selection for mast seeding. We propose that climate-driven resource dynamics in an antecedent population could have synchronised seeding and directly advantaged individuals. These advantages were subsequently amplified through the economies of scale fitness benefits seen today in contemporary tree populations.