Tolerance of a perennial herb, <Emphasis Type="Italic">Pimpinella saxifraga</Emphasis>, to simulated flower herbivory and grazing: immediate repair of injury or postponed reproduction? |
| |
Authors: | A-P Huhta P Rautio K Hellström M Saari J Tuomi |
| |
Institution: | (1) Botanical Museum, Department of Biology, University of Oulu, 90014 Oulu, Finland;(2) Finnish Forest Research Institute, Parkano Research Station, Kaironiementie 54, 39700 Parkano, Finland;(3) Department of Biology, University of Oulu, 90014 Oulu, Finland |
| |
Abstract: | Perennial, polycarpic herbs can respond to herbivory either by (1) regrowth in the same season in order to compensate for
lost reproductive structures or by (2) postponing reproduction until the following growing season. We tested these response
patterns with the perennial umbellifer Pimpinella saxifraga by simulating flower herbivory and shoot grazing both in the field and in a common garden experiment. In the field, both
simulated flower herbivory and grazing effectively suppressed current reproduction, whereas no statistically significant effects
of previous-year treatments on growth or reproduction were found in the following year. In the common garden, in the first
year the species fully compensated for simulated flower herbivory in vegetative parameters but seed set was reduced by 26%.
After 2 years of flower removal, the plants overcompensated in shoot and root biomass by 47 and 46%, respectively, and compensated
fully in reproductive performance. Simulated grazing resulted in 21% lower shoot biomass in the first season, but the root
biomass was not affected. In the second season the root biomass increased by 43% as compared to the control plants. However,
regrowth following simulated grazing resulted in a significant delay in flowering with the consequence that the seed yield
of fertile plants was reduced by 55% as compared to the control plants. These results suggest that in resource-rich garden
conditions P. saxifraga may immediately repair injuries caused by flower herbivory, but repairs more extensive shoot injury less successfully. Delayed
phenology decreases the benefits of immediate repair. In resource-poor conditions, the benefits of regrowth can be negligible.
Accordingly, in our field population, the plants postponed their reproduction until the following year in response to simulated
grazing and frequently in response to flower removal. When the plants gain very little from regrowth, the costs of reproduction
would select for postponed reproduction in response to injury. |
| |
Keywords: | Burnet saxifrage Cost of herbivory Cost of reproduction Fitness Plant life-history Tolerance |
本文献已被 SpringerLink 等数据库收录! |
|