Key Laboratory of Vegetation Ecology, Ministry of Education, Institute of Grassland Science, School of Life Sciences, Northeast Normal University, Changchun, 130024, P.R. China.
Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, 130102, P.R. China.
BMC Plant Biol. 2021 Mar 20;21(1):147. doi: 10.1186/s12870-021-02920-y.
Climate change is predicted to lead to changes in the amount and distribution of precipitation during the growing seasonal. This "repackaging" of rainfall could be particularly important for grassland productivity. Here, we designed a two-factor full factorial experiment (three levels of precipitation amount and six levels of dry intervals) to investigate the effect of precipitation patterns on biomass production in Leymus chinensis (Trin.) Tzvel. (a dominant species in the Eastern Eurasian Steppe).
Our results showed that increased amounts of rainfall with prolonged dry intervals promoted biomass production in L. chinensis by increasing soil moisture, except for the longest dry interval (21 days). However, prolonged dry intervals with increased amount of precipitation per event decreased the available soil nitrogen content, especially the soil NO-N content. For small with more frequent rainfall events pattern, L. chinensis biomass decreased due to smaller plant size (plant height) and fewer ramets. Under large quantities of rain falling during a few events, the reduction in biomass was not only affected by decreasing plant individual size and lower ramet number but also by withering of aboveground parts, which resulted from both lower soil water content and lower NO-N content.
Our study suggests that prolonged dry intervals between rainfall combined with large precipitation events will dramatically change grassland productivity in the future. For certain combinations of prolonged dry intervals and increased amounts of intervening rainfall, semi-arid grassland productivity may improve. However, this rainfall pattern may accelerate the loss of available soil nitrogen. Under extremely prolonged dry intervals, the periods between precipitation events exceeded the soil moisture recharge interval, the available soil moisture became fully depleted, and plant growth ceased. This implies that changes in the seasonal distribution of rainfall due to climate change could have a major impact on grassland productivity.
气候变化预计将导致生长季节降水总量和分布的变化。这种降雨的“重新包装”可能对草原生产力尤为重要。在这里，我们设计了一个两因素完全析因实验（降水总量三个水平和干旱间隔六个水平）来研究降水模式对羊草（欧亚草原东部的优势种）生物量生产的影响。
我们的结果表明，延长干旱间隔的增加降雨量会通过增加土壤水分来促进羊草的生物量生产，除了最长的干旱间隔（21 天）。然而，随着降水总量的增加而延长干旱间隔会降低土壤有效氮含量，特别是土壤硝态氮含量。对于小而频繁的降雨事件模式，由于植物个体较小（株高）和较少的分株，羊草生物量减少。在少数几次降雨量大的情况下，生物量的减少不仅受到植物个体大小和分株数减少的影响，还受到地上部分枯萎的影响，这是由于土壤水分含量和硝态氮含量较低造成的。
我们的研究表明，延长的干旱间隔与大量降雨事件相结合将极大地改变未来草原生产力。对于延长干旱间隔和增加降雨之间的某些组合，半干旱草原生产力可能会提高。然而，这种降雨模式可能会加速可用土壤氮的损失。在极长的干旱间隔期间，降水事件之间的时间间隔超过了土壤水分补充间隔，可用土壤水分完全耗尽，植物生长停止。这意味着由于气候变化导致的季节性降雨分布变化可能会对草原生产力产生重大影响。
