The effect of severe drought on CO2 uptake by plants and carbon dynamics in the plant-soil system
Soil Sciences
Final Report Abstract
As a result of global climate change, the incidence of drought conditions in Europe is predicted to increase in the future, which also influences plant resistance. Lipids are important plant constituents that protect plants against drought stress and contribute to the intermediate stable carbon pool in soil. However, the extent to which drought influences lipid cycling in the plant–soil system is unknown and, therefore, it remains questionable how the ecosystem recovers after drought. We focused on plant and soil samples from two different plant communities (temperate grassland and heathland) that had been exposed to 5 years of 4.5–6.0 weeks repeated annual drought. They were sampled one year after the last drought to check the recovery of the plant– soil system. Samples were analyzed for their bulk C, stable C and nitrogen (N) isotope (δ13C, δ15N) and lipid composition. Contrary to our expectation, no strong influence of five years of repeated annual drought was observed for above-ground biomass, roots and soils in the model ecosystems with respect to elemental (C and N concentrations, C : N ratio) bulk isotope (δ13C, δ15N) composition and the total lipid concentration. Thus, plants did not sustain a significant change in their C and lipid concentration as well as their composition after five years of repeated annual drought. This might be related to the comparatively short drought period related to the overall growth season and provides evidence for recovery of the C and lipid dynamics in temperate grassland and heathland model ecosystems exposed to annual drought. Furthermore, the effect of a severe drought (104 days) followed by irrigation on the plant C uptake, its assimilation and input of C in soil were examined using a triple 13CO2 pulse–chase labeling experiment in model grassland and heathland ecosystems. First 13CO2 pulse at day 0 of the experiment revealed much higher 13C tracer uptake for shoots, roots and soil compared to the second pulse (day 44), where all plants showed significantly lower (20 – 70% less) 13C tracer uptake. After the third 13CO2 pulse (day 70), very low 13C uptake in shoots led to negligible allocation of 13C into roots and soil. During irrigation after the severe drought, 13C tracer that was allocated in plant tissues during the second and third pulse labelings was re-allocated in roots and soil, as soon as the irrigation started. This re-allocation was higher and longer lasting in heathland compared to grassland ecosystems.
Publications
- (2018) Short-term carbon dynamics in a temperate grassland and heathland ecosystem exposed to 104 days of drought followed by irrigation. Isotopes in environmental and health studies 54 (1) 41–62
Srivastava, Kavita; Jentsch, Anke; Kreyling, Juergen; Glaser, Bruno; Wiesenberg, Guido L. B.
(See online at https://doi.org/10.1080/10256016.2017.1371714) - (2017) Repeated annual drought has minor long-term influence on 13C and alkane composition of plant and soil in model grassland and heathland ecosystems. Journal of Plant Nutrition and Soil Science
Srivastava, K., Jentsch, A., Glaser, B., and Wiesenberg, G. L. B.
(See online at https://doi.org/10.1002/jpln.201600019)
