Anna Kirschbaum, Günter Hoch, Oliver Bossdorf, J F Scheepens

Non-structural carbohydrates (NSCs) are important storage reserves of plants, and they may play a key role in the plants’ ability to recover from disturbance events such as drought, fire, or biomass removal. In managed grasslands, plants regularly experience aboveground biomass removal by grazing or mowing. If NSCs influence plant tolerances to these damages, then land-use intensification could lead to adaptive changes in NSC storage allocation. In a common garden experiment, we quantified NSC storage in the taproots of Plantago lanceolata plants from 63 grassland populations that covered a broad range of land-use intensities, and we tested if pre-clipping levels of NSCs correlated positively to land-use intensity and the regrowth ability of plants after aboveground biomass removal. We found significant genetic variation in NSC storage among populations, but in contrast to our expectation NSC storage correlated negatively with mowing intensity and its temporal variation. This suggests that plants from frequently or irregularly mown plots have been selected against investing assimilates into their taproot but rather into aboveground biomass. That only relationships of NSC with mowing, and not with grazing, were detected, could be due to more predictable and homogeneous effects of mowing in contrast to grazing. As NSC variation was unrelated to the regrowth ability of P. lanceolata after aboveground biomass removal, this suggests that this common grassland plant is not C-limited. We conclude that NSCs possibly have only short-term effects on regrowth ability which we did not measure.