Advancement in the Effect of Land Use on Natural Selection of Plant Traits
The research on mechanism of evolutional natural selection of plant traits has been focused on natural environment such as climate and soil factors but less was known to theeffect of ecosystem management and land use .
Prof WANG Wenzheng in the research group of Ecological Stoichiometry IAE and coworkers investigated the transgenerational effect of long-term land use - mowing and grazing regimes- on foraging ability and competitive fitness of offspring in Central Europe.
Seeds of Trifolium repens were collected from 58 populations growing on grasslands with different mowing and grazing intensities and sown in different treatments: without competition, with homogeneous competition, and with heterogeneous competition. The results show that 1) In the competition-free treatment, T. Repens from more productive, less frequently mown, and less intensively grazed sites produced more vegetative offspring, but this was not the case in other treatments. When grown among or in close proximity to competitors, T. Repens plants did not show preferential growth towards open spaces (i.e., no horizontal foraging), but did show strong vertical foraging by petiole elongation. In the homogeneous competition treatment, petiole length increased with the productivity of the parental site, but this was not the case in the heterogeneous competition treatment. 2) The competitor existence significantly reduced the plant fitness：frequency of flowering, vegetative reproduction and above-ground biomass. 3) Petiole length and numbers of vegetative offspring were closely correlated to the community productivity, intensities of mowing and grazing, but the effect was dependent on whether there were competitors in the experiment treatment. 4) We could not differentiate the carry over effect, epigenetic mechanism and typical evolutional mechanism. However, the experiments did indicate that the land use not onlyaffect directly on plant productivity and plant traits, but also show selective pressure indirectly on the trait of offspring. This long-termeffect should be taken into account in the long-term planning of ecosystem management.