Climate change will disrupt the many interactions between biology and climate, from enzymatic reactions to ecological patterns. Climate thoroughly controls key processes such as plant regeneration, as is exemplified by the thermal regulation of seed germination. Temperature drives local adaptation and phenotypic plasticity in germination traits, as well as the physiological processes of dormancy loss and germination elicitation . In seasonal climates, germination traits interplay with annual temperature cycles to ensure that seed emergence and seedling establishment occur in the most favourable season. Given the significance of germination in the life history of a plant, it is not surprising that its timing is a central scenario for natural selection. However, the complex thermal control of germination timing is highly responsive to climate change. New environmental temperatures may not match the temperatures that alleviate dormancy and elicit germination. This mismatch could alter recruitment from the soil seed bank and shift germination timing , compromising plant regeneration and community composition.
A recent paper in Annals of Botany examines the effect of temperature on seed germination using two populations of the wetland sedge Carex diandra, one from a montane site and one from a subalpine site. A cardinal-temperature model was used to simulate changes in germination under two possible future climate scenarios as defined by the Intergovernmental Panel on Climate Change.
Increasing diurnally alternating temperatures decreased the base temperature for seed germination and the thermal time required for germination. The effect of higher alternating temperatures together with the higher temperatures increased germination under both climate scenarios. Carex diandra germination is highly responsive to potential changes in diurnally alternating temperatures, and thus this study highlights the role of temperature changes in seed responses to climate change. Comprehensive cardinal-temperature models, encompassing the different effects of temperature on seed germination, are needed to understand how climate change will affect plant regeneration.
Eduardo Fernández-Pascual, Charlotte E. Seal and Hugh W. Pritchard. (2015) Simulating the germination response to diurnally alternating temperatures under climate change scenarios: comparative studies on Carex diandra seeds. Annals of Botany 115(1): doi: 10.1093/aob/mcu234