Root dynamics along a restoration chronosequence of revegetated grasslands in degraded alpine meadows of the Qinghai‐Tibetan Plateau, China

Abstract

Revegetation using perennial grass, such as Elymus nutans is an effective approach in abating grassland degradation on the Qinghai‐Tibetan Plateau. However, knowledge of root dynamics along restoration chronosequences of revegetated grasslands are limited. To gain better insight into root dynamics, we used minirhizotrons to examine changes in root traits, including root standing crop, production, mortality, and turnover along a restoration chronosequence of three revegetated grasslands (cultivated in 2002, 2006, and 2010 corresponding to late, middle, and early recovery stage) in four consecutive growing seasons (2014, 2015, 2016, and 2017). We found that the aboveground plant biomass was higher in the middle recovery stage than that in the early and late recovery stages, while plant species richness showed an increasing trend from the early to late recovery stage. Similar with the plant biomass response, the belowground root standing crop and production were significantly higher in the middle recovery stage than in the early and late recovery stages. Root mortality was decreased and root turnover tend to be stable from the early to late recovery stage. Root turnover was positively correlated with soil NO3−‐N content and negatively correlated with aboveground plant biomass. Moreover, root standing crop and mortality increased from May to September across all growing seasons; however, root production decreased within this period. Our study highlighted significant links between aboveground and belowground plant parts that may help effectively manage revegetated grassland on the Qinghai‐Tibetan Plateau.