Functionally divergent growth, biomass allocation and root distribution of two xerophytic species in response to varying soil rock fragment content
2021
Hu, Hui | Li, Fanglan | McCormack, M Luke | Huang, Long | Bao, Wei Kai
AIMS: Rock fragments are widespread in soil profiles. Despite direct effects of rock fragment content (RFC) on vegetation and soil properties, how plants respond to variations in RFC remains poorly understood. In this work, we investigated responses of two contrasting xerophytic species to varying RFC. METHODS: Root biomass allocation, vertical distribution and above-ground growth were measured in Artemisia vestita and Bauhinia brachycarpa after 2 years of growth in an experiment with four levels of RFC (0, 25, 50 and 75% ν ν⁻¹). RESULTS: The responses of above-ground growth and total biomass of both species showed a unimodal curve with values increasing up to intermediate RFC (25% and 50%) and then declining. Both species increased relative biomass allocation to roots at the highest RFC level (75%). A. vestita had a shallow rooting profile and greater declines in plant growth with high RFC compared with B. brachycarpa which had a deeper rooting profile. CONCLUSION: We found that intermediate RFCs were beneficial for growth of both species and both species increased root-to-shoot ratios to compensate for high RFC. The higher overall root fraction and deeper rooting profile may make B. brachycarpa more suitable than A. vestita for areas with high RFC, enabling greater extraction of increasingly limited soil resources.
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