Rainfall in growing season determines the size of an annual-dominated
soil seed bank in a desert ecosystem
Abstract
Soil seed banks may offer great potential for restoring and maintaining
desert ecosystems that have been degraded by climate change and
anthropogenic disturbance. However, few studies have explored the annual
dynamics in the composition and relative abundance of these soil seed
banks. We conducted a long-term observational study to assess the
effects of environmental factors (meteorology and microtopography) and
aboveground vegetation on the soil seed bank of the Tengger Desert,
China. The desert seed bank was dominated by annual herbs. We found that
more rainfall in the growing season increased the number of seeds in the
soil seed bank, and that quadrats at relatively higher elevations had
fewer seeds. The species composition had more similarity in the seed
bank than in the aboveground vegetation, though the seed bank and
aboveground vegetation did change synchronously due to the rapid
propagation of annuals. Together, our findings suggest that the combined
effects of environmental factors and plant life forms determine the
species composition and size of soil seed banks in deserts. Thus, if
degraded desert ecosystems are left to regenerate naturally, the lack of
shrub and perennial herb seeds could crucially limit their restoration.
Human intervention and management may have to be applied to enhance the
seed abundance of longer-lived lifeforms in degraded deserts.