How do shoot clipping and tuber harvesting combine to affectBolboschoenus maritimusrecovery capacities?

Abstract

In French Mediterranean wetlands, the combined effects of predation of tubers by wildlife and grazing of aboveground tissue by livestock on the recovery capacities of Bolboschoenus maritimus (L.) Palla are not well known. A container study was conducted that applied tuber harvests at varying levels (20%–90%) and shoot clipping (with or without). Response to harvesting and clipping was recorded as changes in total biomass, number, and mean mass of tubers (calculation of variation indexes). Bolboschoenus maritimus failed to recover from even the lowest tuber harvesting level of 20% and the total number of tubers and biomass decreased. A significant decrease in mean tuber mass over time and approximately no production of new tubers accounted for this absence of compensatory response. The harvesting level had a linear effect on the variation indices of total number of tubers and mean tuber mass. By separating the relative effect of shoot clipping from that of tuber harvesting alone, the results showed that clipping had an additive effect on mean tuber mass, reducing it by about 20%, without any effect on tuber number. The absence of compensatory response under our experimental conditions suggests that clonal plant regrowth partially depends on post-disturbance environmental conditions in the growing season, in our case, dry conditions.