Environmental stress gradients mediate plastic trade-offs between growth and carbon storage in dominant desert shrubs

Dominant shrub species in temperate deserts exhibit specialized
adaptations and divergent evolutionary strategies in response to varying
and extreme environmental stresses. However, it remains unclear how shrub
species balance growth and carbon storage to cope with abiotic combined
stresses across extensive spatiotemporal gradients. Guided by the
Soil-Plant-Atmosphere Continuum (SPAC) theory and combined with a 20-year
monitoring of non-structural carbohydrates (NSC), we conducted extensive
field surveys across a representative temperate desert area. Using
ensemble learning on 60 integrated environmental variables, the region was
automatically classified into four SPAC systems that reflect gradients of
combined temperature, precipitation, radiation, soil properties, and other
factors. Results revealed divergent trade-offs between growth and carbon
storage of shrubs mediated by intensity and combination of stresses.
Shrubs in the Qinghai-Tibet Plateau faced severe temperature-water
stresses, with growth limited by carbon storage. In contrast, shrubs in
the Ningxia-Shanxi region tended to promote growth in minimal water
stress. NSC mobilization and internal transport capacity were key
determinants of shrub resilience to extreme climate events. These findings
suggest that long-term evolutionary processes have shaped flexible carbon
allocation strategies along environmental gradients. Therefore,
understanding these adaptive strategies is crucial for predicting
vegetation dynamics and ecosystem resilience under future climate
scenarios.