DO ARCTIC PLANT-SOIL COMMUNITIES ACCLIMATE TO LONG TERM ELEVATED CO2 EXPOSURE?

Lead Research Organisation: NERC CEH (Up to 30.11.2019)
Department Name: Shore

Abstract

Se Lead.
 
Description 1. Introduction - The core experiment was based is located in sub-Arctic heath near the Abisko Research Station (68oN), in Northern Sweden. Subsidiary investigations were undertaken on adjacent heath and at Aberystwyth University. The importance of this research is illustrated by the meta-analysis carried out as part of the project (Jones et al., 2014). Boreal regions are under-represented in elevated CO2 (eCO2) research and below-ground impacts are often not considered. 2. Current plant characteristics - Shoot length measurements for the dominant dwarf shrub species were disrupted by severe insect herbivory in 2012 and 2013 but not in 2104. In 2014 eCO2 did not affect above ground growth of the dwarf shrubs or shoot and root N/C concentrations in 2014 but N concentrations varied between species and root type. Vaccinium vitis-idaea cover was reduced at eCO2. eCO2 caused marked increases in coarse root mass in 2014. Since coarse roots accounted for ~ 25% of the soil mass, this response represents a significant C sink. Coarse roots may represent cumulative long-term effects of eCO2 whereas fine roots may reflect more recent responses. 3. Soil C amounts and form - In bulk soil samples (2014) eCO2 had no significant effect on microbial biomass-C, dissolved-C or respired C. The absence of any eCO2 effect suggests that the coarse root fraction did not interact with more labile C pools. In a short-term study, roots of Calamagrostis purpurea changed composition in response to eCO2 and rhizosphere leachate pH decreased; secondary root frequency was also higher. Roots responded to eCO2 by enhancing nutrient acquisition capacity. 4. Photosynthate transfers - Much of the additional C fixed at eCO2 has been allocated to coarse roots, whose high C:N ratio would favour their persistence. C isotope data broadly support this interpretation. 5. Net species and ecosystem C exchanges - Gas fluxes measured in 2012 and 2013, but not in 2011, were seriously affected by defoliation (larvae of Epirrita autumnata). Whereas earlier monitoring indicated that eCO2 increased photosynthesis, in 2012 net ecosystem exchange and community photosynthesis was significantly lower. Findings suggest increased retention of C under stress at eCO2. 6. Ecosystem stability in response to perturbations - We used artificial defoliation, natural defoliation (caused by outbreak), enhanced UV-B and installation of root ingrowth tubes to look at system resilience. Defoliation resulted in a reduction in ecosystem respiration and an impact on soil enzymes. The dominant species Empetrum hermaphroditum was identified as central to soil C dynamics in this system. For root ingrowth tubes eCO2 increased root biomass and, total and fungal PLFAs (phospholipid fatty acids) but only at enhanced UV-B. Summary of key outcomes: a) Highlighted the global relevance of key questions in the journal Environment International. b) Evidence that long-term exposure to elevated CO2 continues to stimulate photosynthesis with additional carbon sequestered into coarse roots. c) Produced ten publications (others in prep) and 30 direct engagement activities. d) Stimulated further funding applications.
Exploitation Route This research investigated the long-term effects of elevated concentrations of CO2 on the carbon dynamics of sub-arctic heath communities. Findings will be of interest to a significant academic audience, as the research is unique in looking simultaneously at all the major aspects of carbon dynamics in the heath. This study comprehensively monitored aspects of plant productivity, canopy gas exchange, microbial diversity, soil respiration and future ecosystem stability. The research outcomes will provide invaluable information for increasing the accuracy and predictive power of global climate models (GCMs), with respect to climate-atmosphere-soil interactions in these globally extensive biomes. Current GCMs contain relatively unsophisticated parameterisation of soil-plant components, and their responses to climate change. Published outcomes will feed directly to a range of international scientific panels and networks including the Intergovernmental Panel on Climate Change, UNEP Millennium Assessment (Ecosystems' Polar), International Arctic Science Committee, Interface and the International Conferences on Arctic Research Planning and others. The findings from this research will also be of interest to policy makers and managers in regions of the UK and EU. The research has relevance in terms of the ecosystem services of particular habitats including upland peat and heath systems and the positive value of C conservation.
Sectors Agriculture, Food and Drink,Education,Environment
 
Description This research has produced output that will be of international relevance in the future as it targets the contribution of existing ecosystems in mitigating greenhouse gas emissions. In the shorter term it used engagement to impact on individuals, schools and society to make the public and policy makers aware of the importance of the questions addressed via this research. The longer term aim is that outcomes impact and influence these sectors, particularly policy. Further research leading to potential commercial outcomes have started to emerge from this initial research. This will introduce its own impacts and if realised could provide economic benefits to the UK.
First Year Of Impact 2019
Sector Agriculture, Food and Drink,Education,Environment
Impact Types Societal,Policy & public services