Precipitation amount and frequency affect seedling emergence and growth of Reaumuria soongarica in northwestern China

Abstract

Climate change is shifting the amount and frequency of precipitation in many regions, which is expected to affect seedling recruitment across ecosystems. However, the combined effects of precipitation amount and frequency on seedling recruitment remain largely unknown. An understanding of the effects of precipitation amount and frequency and their interaction on seedling emergence and growth of typical desert plants is vital for managing populations of desert plants. We conducted two experiments to study the effects of variation in precipitation on Reaumuria soongarica (Pall.) Maxim. First, greenhouse experiments were conducted to examine the effects of three precipitation amount treatments (ambient, +30%, and −30%) and two precipitation frequency treatments (ambient and −50%) on seedling emergence. Second, the morphological responses of R. soongarica to changes in precipitation amount and frequency were tested in a controlled field experiment. Stage-specific changes in growth were monitored by sampling in different growth seasons. Our results showed that precipitation amount significantly affected germination, seedling emergence, and growth of R. soongarica, and there was a larger effect with decreased precipitation frequency compared with ambient. Germination and seedling emergence increased as precipitation increased under the same frequency of precipitation. The highest emergence percentage was obtained with a 30% increase in precipitation amount and a 50% reduction in precipitation frequency. Compared with ambient precipitation, a 30% increase in precipitation amount increased above-and below-ground biomass accumulation of R. soongarica during the growth season. A decrease of 30% in precipitation amount also resulted in an increase in below-ground biomass and root/shoot ratio in the early stages of the growth season, however, above-and below-ground biomass showed the opposite results at the end of the growth season, with larger effects on above-ground than below-ground biomass under decreased precipitation frequency. When precipitation frequency decreased by 50%, values of all growth traits increased for a given amount of precipitation. We concluded that precipitation frequency may be as important as precipitation amount to seedling emergence and growth of R. soongarica, and that understanding the effects of precipitation variability on seedling recruitment requires the integration of both precipitation amount and frequency. In particular, the combination of a 30% increase in precipitation amount and 50% reduction in precipitation frequency increased the emergence and growth of seedlings, suggesting that alteration of amount and frequency of precipitation caused by climate change may have significant effects on seedling recruitment of R. soongarica.

Impact of artificially simulated precipitation patterns change on the growth and morphology of Reaumuria soongarica seedlings in Hexi Corridor of China

“…This study found that the increase of 30% in precipitation significantly increased the plant height, above-ground biomass, and total biomass of R. soongarica. This result is similar to that of Duan et al and Shan et al [18,20]. However, some studies have suggested that increasing precipitation does not significantly promote the growth of desert plants [10].…”

“…This shows that reducing the frequency of precipitation is better than the frequency-invariant treatment, but the impact is slight. The results are consistent with those of Schneider and Shan [13,20]. Gao et al [11] believed that the values of all nutritional and reproductive traits in plants increase with increasing precipitation frequency.…”

“…This result supports previous findings. However, the increase and decrease of water in October 2017 and July 2018 had no significant impact on the growth of the subsurface, which is basically the same as the result of Shan's study [20]. The increase in precipitation in October 2018 significantly promoted the accumulation of below−ground biomass and changed significantly from previous trends.…”

“…Some research [31] shows that the interaction between precipitation amount and precipitation frequency affects the main root length of (Nitraria spp), seedlings, above-ground biomass of R. soongarica seedlings [19], below−ground biomass, and total biomass [18]. There is an interaction between growth rates [20]. However, the results of this research did not find that there was an interaction between precipitation amount and frequency on R. soongarica seedling growth (Table 2), possibly because of different research objects.…”

“…It also has a more fragile development stage during plant growth and it is extremely sensitive to ecosystem disturbance [11,12]. At present, research on the impact of precipitation and changes in precipitation frequency on the morphology of R. soongarica seedlings has been reported [18][19][20], but has only studied annual R. soongarica seedlings. The complete life cycle of R. soongarica is several decades, so it is necessary to study the seedlings for a longer time.…”