Patterns of reproductive allocation in Artemisia halodendron inhabiting two contrasting habitats

The perennial chenopod sub-shrub Artemisia halodendron Turcz. ex Bess. is endemic to the semi-fixed and mobile sand dunes in Inner Mongolia of northern China and is an important sand-stabilizing plant. A. halodendron can persist through either sexual reproduction (seedling recruitment) or vegetative propagation. However, it is not known if there are differences in patterns of reproductive allocation in A. halodendron inhabiting semi-fixed and mobile habitats. To characterize this, a test of field measurements was conducted on two typical semi-fixed and mobile sand dune habitats. In each habitat, 120 individual A. halodendron plants were randomly sampled at the time of seed production to examine changes in some reproductive characters including the number of flowering shoots, dry weight of flowering shoots, dry weight per flowering shoot, dry weight of seed, and reproductive effort (RE = seed dry weight/total above-ground dry weight) between habitats. Although total above-ground dry weight and dry weight of vegetative biomass were similar between habitats, plants inhabiting the less eroded semi-fixed habitat produced more flowering shoots, greater dry weight of flowering shoots, dry weight of seed and RE than those inhabiting the more eroded mobile habitat. This suggests that sexual reproduction is relatively favored by plants from the semi-fixed habitat, whereas vegetative propagation is favored by plants from the mobile habitat. The allocation of resources to reproduction was size-dependent and specific to habitats sampled. Reproductive biomass and the number of flowering shoots per plant increased with increasing vegetative biomass, with plants in the semi-fixed habitat producing more flowering shoots and greater reproductive biomass than plants in the mobile,habitat. Plant size did not influence RE, indicating that allocation of resources to reproduction appeared to be a constant proportion across all plant sizes sampled. (c) 2005 Elsevier SAS. All rights reserved.