Eremosparton songoricum, a rare and endemic sand dune plant, appears to be experiencing recruitment failure. The structure of five populations from the Gurbantunggut Desert, China, was investigated for recruitment patterns, and two of them were examined for flowering, pollination and seed germination limits on regeneration. The results showed that total 150 seedlings only occurred on line transects in riverside Dure population, but they all died half a month later; no seedlings occurred in other four hinterland desert populations indicating recruitment was a failure at all populations although flowers were plentiful. Reproductive success depends on pollinators. Nectar is 'reward' for pollinators, with 0.06 µL-0.12 µL and 0.15 µL-0.35 µL per flower in Dure and Kabu populations, respectively, in continuously two secreting days. Spontaneous self pollination is rare with nearly zero fruit production. Geitonogamous self pollination is predominant with 14.47% fruit set. Seed mass in the riverside Dure population was significantly greater than that in other hinterland desert populations. Consequently, the Dure population exhibited a significantly higher germination rate (about 90%) than those in other populations (about 30%). Results suggested that recruitment failure of E. songoricum is not due to flower shortage, pollination limitation, or poor seed germination but environmental pressure and/or human disturbance.
Eremosparton songoricum (Fabaceae) is a rare, native, clonal small shrub of the deserts of central Asia. Although human activities have greatly fragmented the distribution of E. songoricum, it occurs in areas where artificial sand fixing (AS) has been implemented. We sought to explore whether AS promotes survival and growth of E. songoricum. In the Gurbantunggut Desert of northwestern China in June 2010, we established 10 plots in an area where sand fixing occurred (5-10 years previously) and 11 plots on original sand substrate on which some plants had settled without fixing sand. Sand fixing changed soil properties and biological characteristics in sand-fixed plots. The soil surface where sand fixing occurred was covered by algal crusts and some lichen, but not bare sand (BS). Soil nutrients; water content of deep soil (30-150 cm); overall plant and herbaceous species richness, diversity, abundance, and cover; above- and belowground biomass; and cover, biomass, and height of E. songoricum in the sand-fixed plots were significantly greater than in plots of BS. However, distribution of E. songoricum individuals in the 2 types of plots did not differ. Our results indicate AS may enhance survival of E. songoricum and increase the overall diversity and stability of the desert plant community. We suggest AS as a way to protect this rare desert plant in situ.
In this study, the soil moisture content was measured, and the quantitative characteristics of this sedge species were compared. The phenotypic plasticity of each parameter and the linear regression relationships were analyzed. The results showed that the soil moisture content was significantly affected by location, soil depth, and sampling date. The aboveground biomass, underground biomass, biomass density, and population density at the peak were significantly higher than elsewhere on the dune. However, the morphological plasticity index of the quantitative characteristics was higher at the base and middle of the dune. When the soil moisture content decreased, the underground biomass and ramet biomass density increased. The aboveground and underground biomasses were strongly negatively correlated, but the ramet height and aboveground biomass were strongly positively correlated. These results indicated that the soil water content significantly affected the clonal growth of C. physodes. The responsiveness of C. physodes may be adaptive when the soil resource supply is low. The strong morphological plasticity of the species appears to be ecologically important for the maintenance and dominance of this species in the dune habitat.
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