Terrestrial vegetation is involved in the regulation of global carbon and water cycles. As such, the physiological responses of plants to climate change could influence how these cycles function. The magnitude of the physiological responses of plants to climate change has been found to decrease with time. This indicates that there may be long-term processes of acclimation and adaptation in plants. Isotope analysis of archived plant material offers an opportunity to reconstruct the physiological activity of plants over long time periods. It also allows scientists to assess how physiological responses to climate change may vary in different plant species from different environments. The EU-funded LEAFISOTRENDS (Long-term physiological responses of herbaceous plant species from contrasting functional groups and environments to centennial climate change) initiative studied century-long physiological responses of various herbaceous plant species from different habitats across Switzerland to past changes in climate. The scientists did this by analysing the carbon, nitrogen and oxygen isotope compositions of archival herbarium plant specimens. LEAFISOTRENDS scientists analysed 3 334 specimens from 85 herbaceous plant species, collected between 1820 and today from locations with differing environmental conditions. Their results show that herbaceous plants have increased their intrinsic water-use efficiency since 1850 in response to the increasing concentration of atmospheric carbon dioxide. This research shows a combination of increased photosynthesis and reduced stomatal conductance may be responsible for the change. Project work also showed a positive relationship between intrinsic water-use efficiency and oxygen isotope composition across time, locations and plant functional types. This important finding reveals how closely carbon and water cycles are linked to global environmental changes. The results from this project corroborate the findings of other short-term research that assessed plant responses to climate change. The results also highlight that plant physiological responses may differ across functional types and environmental conditions. Research conducted by LEAFISOTRENDS will help to ensure that these factors are considered when building models of global change.
Physiological response, plants, climate change, carbon and water cycles, LEAFISOTRENDS