Above and underground traits vary in response to soil moisture availability and plant competition

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Functional traits have been used to explain plant responses to changes in water availability. Our understanding of plant responses to biotic and abiotic drivers depends largely on the plant’s aboveground traits. Due to limited consideration of the characteristics of underground plants, an overview of plant water use strategies remains elusive.

In a study published in Annals of botanyIn this study, researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences attempted to study and compare the response of above- and below-ground traits and biomass allocation patterns to soil and plant moisture. Competition treatments.

The researchers selected seedlings from five tropical tree species and planted them in a greenhouse for 16 weeks under a soil moisture gradient (low moisture levels (dry), medium and high (well hydrated)) with and without indefinite competition. At harvest, they measured nine aboveground traits and five underground traits for all seedlings based on standard protocols.

They found that above and below ground traits have heterogeneous responses and inconsistent correlations with soil moisture availability and plant competition. In response to the soil moisture gradient, it was found that the aboveground traits are compatible with the leaf economics spectrum while the underground traits are not compatible with the root economics spectrum. Specific leaf area was positively correlated with specific root length, while it was negatively correlated with mean root diameter across moisture levels. However, the dry matter content of the leaves was unexpectedly positively correlated with both specific root length and root branching index.

Indeterminate competition affected both above- and below-ground traits, but interacted with soil moisture to affect only the underground traits. However, the allocation of biomass to above- and below-ground plant organs via a soil moisture gradient supports the functional equilibrium theory where relatively larger proportions of biomass are allocated in organs that capture limited water resources for growth.

“Our results indicate that the response of underground traits to nonspecific competitor plants soil moisture Conditions may not be inferred using above-ground features. Plants may use a range of environmental strategies in response to variability environmental changesYang Jie from XTBG said.


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more information:
Mengesha Asefa et al, traits of above and below ground plants are incompatible in response to drought and competition treatments, Annals of botany (2022). DOI: 10.1093/aob/mcac108

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