Abstract:

Aims: Exploring the intraspecific and interspecific variations in plant functional traits is not only beneficial for understanding plant adaptation to different environmental factors, but also helpful as a reflection on the ecological strategy. However, the adaptation strategies of root and leaf morphological traits in the growth process of different mycorrhizal tree species need to be explored.

Methods: We studied seven arbuscular mycorrhizal (AM) tree species and seven ectomycorrhizal (EM) tree species in the Biodiversity-Ecosystem Functioning Experiment China Platform (BEF-China). We studied the characteristics of root and leaf morphological traits of different mycorrhizal tree species by measuring the following morphological traits and growth indices: specific leaf area, leaf dry matter content, specific root length, average diameter, the growth rate of tree height, the growth rate of basal diameter, and fine root biomass.

Results: We found that when compared with AM tree species, EM tree species had lower specific leaf area, average diameter of absorbing root, and growth rate (including tree height and basal diameter). EM species had a higher leaf dry matter content. There were no significant differences in the specific root length and fine root biomass between the two types of mycorrhizal tree species. There were significant differences in specific leaf area, leaf dry matter content, the growth rate of tree height, the growth rate of basal diameter and fine root biomass between tree species, mycorrhizal types and the interaction between the two. Additionally, tree species, root functional type, mycorrhizal type and the interaction between tree species with root functional types and mycorrhizal types had significant effects on root functional traits. The intraspecific variation of the aboveground growth indices of EM tree species was greater than that of interspecific variation, whereas the intraspecific variation was similar to the interspecific variations of the above-ground indices of AM tree species. Furthermore, the intraspecific variation was greater than the interspecific variation of fine root biomass for all tree species. Although the above-ground growth for two types of mycorrhizal tree species had a faster growth rate, they usually showed low leaf dry matter content. AM tree species had a high specific root length for absorbing roots, while EM tree species had a high average diameter for transporting roots. Low specific root length of the absorbing roots greatly increased the fine root biomass for all the tree species.

Conclusions: Therefore, there was a certain synergistic effect between root and leaf morphological traits on plant growth above ground. Transporting roots mainly played an important role in the above-ground growth of EM tree species. Whereas absorptive roots mainly were related to the above-ground growth of AM tree species. However, below ground growth was mainly related to the absorptive root for all tree species.

Key words: root and leaf functional traits, plant growth, fine root biomass, aboveground-belowground relationship, mycorrhizal types