Fine root (diameter ≤2 mm) is the key plant organ for nutrients and water uptake, and is also important for carbon (C) and nutrient cycling. Global warming has complex effects on vegetation dynamics and nutrient cycling in terrestrial ecosystems. However, how warming alter fine root traits remains unclear in forest ecosystems.

In order to identify the effects of warming on fine-root traits of woody plants, Dr. ZHAO Xiaoxiang from Wuhan Botanical Garden, conducted a meta-analysis based on 431 paired observations of 13 fine root traits from 78 studies across the world. How would warming magnitude, warming duration and climate conditions regulate the effects of warming on these fine-root traits were also assessed.

The results showed that warming had minimal effect on fine root biomass, root production and morphological traits. Warming increased fine-root nitrogen(N) concentration, root respiration and root mortality, but decreased root nonstructural carbohydrates (NSC) concentration, fine root phosphorus concentration, and root C:N.

With the increasing of warming magnitude, the effect sizes of warming on fine root biomass and root diameter decreased. Moreover, the effects of warming on specific root length, root length shifted from negative/no- change to positive, and the root C:N shifted from negative to no-change with the increase of warming duration.

With increasing mean annual temperature and mean annual precipitation, the effects size of root biomass, root diameter, root length and root C:N decreased, the effects size of fine root N concentration increased.

These results emphasized warming could regulate fine-root traits to adapt the environmental changes. Moreover, the effects of warming on fine root traits were also modulated by warming duration, warming magnitude, and also climate conditions.

These results could improve our ability to predict the responses of fine root to climate change in shrubs and tree-dominated ecosystems and leading to a better understanding of forest belowground processes under climate change.

The research entitled “The effect of experimental warming on fine root functional traits of woody plants: Data synthesis” was published in Science of the Total Environment. This work was supported by the National Natural Science Foundation of China.

The effect of warming on fine root traits. Numbers on the right of the figure represent observations. The effect of warming was not significant when the 95 % CIs cover zero. (Image by WBG)

The effect of warming magnitude and warming duration on fine root traits. The effect of warming magnitude or warming duration was not significant when the 95 % CIs cover zero. (Image by WBG)