Abstract:

Ubiquitous thermal acclimation of leaf respiration could mitigate the respiration increase. However, whether species of different plant functional groups showing distinct or similar acclimation justifies the simple prediction of respiratory carbon (C) loss to a warming climate.

In this study, leaf dark respiration (Rd) of illinois bundleflower (IB, legume), stiff goldenrod (GR, C3 forbs), indian grass, little bluestem and king ranch bluestem (IG, LB and KB, C4 grass) were measured with detached leaves sampled in a 17-year warming experiment.

The results showed that Rd at 20°C and 22°C (R20 and R22) were significantly lower in the warming treatment for all the five species. Lower R22 in warmed than R20 in control in GR, KB, LB and IG imply acclimation homeostasis, but not in IB. The significant decline in temperature sensitivity of respiration (Q10) of GR resulted in the marginal reduction of Q10 across species. No significant changes in Q10 of C4 grasses suggest different acclimation types for C3 forbs and C4 grass. The magnitude of acclimation positively correlated with leaf C/N. Our results suggest that non-legume species had a relative high acclimation, although the acclimation type was different between C3 forbs and C4 grasses, and the legume species displayed no acclimation in Rd. Thus, the plant functional types should be taken into account in the grassland ecosystem C models.

Key words: acclimation, dark respiration, warming, legume, plant functional types