Soil-driven dry–hot events cut vegetation GPP by an extra 1.115 g·C·m⁻²·day⁻¹ versus atmospheric ones
Global analysis of several GPP datasets: heat with soil moisture deficit deepens productivity loss and delays recovery by 2.238 days on average versus atmospheric dry–hot events.
A team led by Shuzhe Huang and Siqi Wang reported in The Innovation Geoscience (2026, volume 4, article 100235) that compound dry–hot events driven by soil moisture deficits reduce global vegetation productivity more than events driven by atmospheric conditions. Using multiple gross primary productivity (GPP) datasets together with climate variables, the authors quantified GPP loss and recovery time worldwide. On average, soil-driven events cut GPP by an additional 1.115 g·C·m⁻²·day⁻¹ and prolonged recovery by 2.238 days doi.org
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Two types of compound events
The authors separate compound meteorological dry–hot (CMDH) events from compound soil dry–hot (CSDH) events. CMDH events pair heat with atmospheric dryness, expressed as high vapor pressure deficit. Plants close their stomata and photosynthesis dips, but the dip reverses quickly once the air recovers. CSDH events pair heat with soil moisture deficits, which constrain root water uptake and hydraulic integrity. In this case, carbon uptake cannot restart until the soil recharges.
Structural equation modeling and explainable machine learning showed a shift in the controlling mechanism: atmospheric demand under CMDH, soil moisture limitation under CSDH. According to the authors, this explains both the deeper carbon losses and the longer "ecosystem memory", because accumulated moisture deficits persist for weeks to months.
Where and how the gap grows
The additional loss concentrates in the mid-latitude semiarid belt and in monsoon–temperate transition zones, and in forests. Woody ecosystems, with higher productivity baselines and more intricate root-water strategies, showed deeper losses and slower rebounds than grasslands and croplands doi.org
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The difference has widened over recent decades. The gap in GPP loss between CSDH and CMDH events increased by about 0.003 g·C·m⁻²·day⁻¹ per year, and the gap in recovery time by about 0.006 days per year. The dominance of soil-driven effects also strengthens with event severity and climate aridity.
For future scenarios, the study reports that under high-emission pathways such as SSP3-7.0 and SSP5-8.5 soil-driven events increasingly dominate, implying deeper carbon losses and longer recovery for ecosystems.
The authors argue that ecosystem-vulnerability and carbon-sink assessments should include soil moisture dynamics, along with deep soil and groundwater recharge, ecological memory and human interventions such as irrigation doi.org
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