Abstract
Future increased precipitation in cold desert ecosystems may impact annual/ephemeral plant species that germinate in both spring and autumn. Our primary aim was to compare the life history characteristics of plants from spring-germinating (SG) and autumn-germinating (AG) seeds of Erodium oxyrhynchum. Plants in field plots with simulated increases in precipitation of 0, 30 and 50 % in spring and summer were monitored to determine seedling survival, phenology, plant size, seed production and biomass accumulation and allocation. Germination characteristics were determined in the laboratory for seeds produced by plants in all increased precipitation treatments. Increased precipitation in spring significantly improved survival of seedlings from SG and AG seeds, but survival was less for AG than SG. An increase in precipitation increased the number of seeds per plant for both SG and AG, but AG produced more seeds per plant than SG. With increased precipitation, percentage of dormant seeds from SG increased significantly, while that of AG decreased slightly. Our study suggests that with increased spring and summer rainfall AG will produce an increased number of nondormant seeds that could germinate in autumn and SG an increased number of dormant seeds that become part of the soil seed bank. However, ability of some seeds to germinate in autumn and others in spring will be maintained as long as soil moisture is limited in autumn.
Highlights
The global and regional water cycle is changing, and this will have a great impact on terrestrial ecosystems (Stocker et al 2013)
In the context of increased precipitation, the differences of SG and AG in seed dormancy avoid the risk of population extinction from a one-time germination event, and enhance competitivenessof the species in the plant community. For both AG and SG, increased precipitation prolonged the life cycle; increased dry mass accumulation and seed production; increased the proportion of biomass allocated to stems and leaves; and decreased the proportion of reproduction and roots
The effect of increased precipitation with climate change could modify the proportion of dormant and nondormant seeds produced by SG and AG
Summary
The global and regional water cycle is changing, and this will have a great impact on terrestrial ecosystems (Stocker et al 2013). Since plants are a critical part of terrestrial ecosystems, changed water cycles inevitably will affect their growth and reproduction (Prieto et al 2008; Husen et al 2017). The effects of increased/decreased amount of precipitation on the different life history stages of plants are an important issue in ecological research (Bai et al 2008; Franks and Weis 2008; Gornish et al 2015). The annual nondesert species Polygonum cascadense allocated more biomass to reproductive organs in dry than in wet years (Hickman 1975). Seeds produced in cool wet years often are more dormant than those produced in dry warm years (Eslami et al 2012; Baskin and Baskin 2014)
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