Germination Strategies and Patterns of Annual Species in the Temperate Semiarid Region of China

Seed germination traits play a key role in the persistence and dynamics of annual desert plants, which enables predicting potential vegetation changes corresponding to environmental changes. Information on seed germination of annual species in the temperate semiarid region of China is limited. A laboratory study was conducted to evaluate the seed germination behavior of 17 annual species collected from a wide range of habitats in the Wulanaodu region of Horqin sandy land. Measurements were conducted on freshly collected seeds and on samples subjected to chilling and dry storage for 150 days and 365 days. Three species achieved germination percentages greater than 90% in any storage condition. Eight species had an after-ripening mechanism, and freshly collected seeds could mature and germinate in a single growing season. Three species had strong innate dormancy, and this fraction (18–50%) of seeds did not germinate even after dry storage for 365 days. Two species had short-lived seeds, whose longevity was less than one year. The majority of annual species showed potential for rapid germination and a unimodal germination curve with time, expressed as the proportion of seed germinated per day. A minority of the species had long germination duration and exhibited a multimodal process. Seventeen annual species produced four germination patterns and two germination strategies based on germination percentages and processes. Species with high germination percentages, short germination duration and a unimodal curve, exhibited risk-taking strategy in a growing season. Species with a low final germination fraction or long germination duration and a multimodal curve or both, showed a risk avoiding strategy. The adaptability to uncertain environments of some annual species in temperate semiarid region is discussed.