<Emphasis Type="BoldItalic">Key message</Emphasis> Continuous monitoring of stem water potential and circumference variation reveals a relationship between apparent stem capacitance and Ψ-mapped embolism risk during drought, providing a mechanistic and practical proxy to assess hydraulic safety in mature conifers. Abstract Projected increases in drought frequency and intensity threaten the hydraulic function and survival of mature conifers. However, continuous in-situ monitoring of stem water status remains technically challenging, particularly within forest canopies. We deployed microtensiometers and precision dendrometers in a thinned Pinus sylvestris stand (Sierra Nevada, Spain) to monitor hourly stem water potential (ΨSTEM) and stem circumference variation (SCV). Stem hydraulic capacitance (CS) was derived in situ from SCV– ΨSTEM time series. Embolism risk, PLC (Ψ), was estimated at diagnostic intervals by mapping in-situ ΨSTEM onto laboratory vulnerability curves. Continuous ΨSTEM closely matched independent leaf pressure-chamber measurements (R² = 0.78) and covaried with sub-daily SCV dynamics, validating both sensors. Midday SCV (SCVMD) covaried with midday Ψᴍᴅ (R² = 0.49) and with Ψ-mapped embolism risk (PLC (ΨMD)) (R² = 0.51), indicating that greater shrinkage aligns with more negative tension and higher estimated risk. Across the dry-down, PLC (Ψ) indicated rising risk while CS declined; we interpret this as a plausible capacitance–risk linkage given our design. Concurrent eddy-covariance measurements showed late-summer attenuation of canopy latent energy (LE), with lower midday peaks and reduced diurnal amplitude-coincident with higher PLC (Ψ) estimates and declining CS. Mixed-effects modeling revealed that SCV was jointly driven by ΨSTEM, air temperature, vapor-pressure deficit, relative humidity, and most prominently soil water content. Together, these results demonstrate that non-destructive, high-temporal-resolution sensing resolves diel–seasonal hydraulics and support a capacitance–embolism risk trade-off. We further show that SCVMD provides a practical proxy for hydraulic status where direct tensiometry is impractical, informing physiologically based forest management. Graphical abstract

Tracking drought-driven hydraulic impairment in Pinus sylvestris with microtensiometry and dendrometry

期刊论文
出版模式：

开放获取
发表日期：

2026年1月20日

查看全文

Antonio M. Cachinero-Vivar,
Óscar Pérez-Priego

摘要

Key message

Continuous monitoring of stem water potential and circumference variation reveals a relationship between apparent stem capacitance and Ψ-mapped embolism risk during drought, providing a mechanistic and practical proxy to assess hydraulic safety in mature conifers.

Abstract

Projected increases in drought frequency and intensity threaten the hydraulic function and survival of mature conifers. However, continuous in-situ monitoring of stem water status remains technically challenging, particularly within forest canopies. We deployed microtensiometers and precision dendrometers in a thinned Pinus sylvestris stand (Sierra Nevada, Spain) to monitor hourly stem water potential (Ψ_STEM) and stem circumference variation (SCV). Stem hydraulic capacitance (C_S) was derived in situ from SCV– Ψ_STEM time series. Embolism risk, PLC (Ψ), was estimated at diagnostic intervals by mapping in-situ Ψ_STEM onto laboratory vulnerability curves. Continuous Ψ_STEM closely matched independent leaf pressure-chamber measurements (R² = 0.78) and covaried with sub-daily SCV dynamics, validating both sensors. Midday SCV (SCV_MD) covaried with midday Ψᴍᴅ (R² = 0.49) and with Ψ-mapped embolism risk (PLC (Ψ_MD)) (R² = 0.51), indicating that greater shrinkage aligns with more negative tension and higher estimated risk. Across the dry-down, PLC (Ψ) indicated rising risk while C_S declined; we interpret this as a plausible capacitance–risk linkage given our design. Concurrent eddy-covariance measurements showed late-summer attenuation of canopy latent energy (LE), with lower midday peaks and reduced diurnal amplitude-coincident with higher PLC (Ψ) estimates and declining C_S. Mixed-effects modeling revealed that SCV was jointly driven by Ψ_STEM, air temperature, vapor-pressure deficit, relative humidity, and most prominently soil water content. Together, these results demonstrate that non-destructive, high-temporal-resolution sensing resolves diel–seasonal hydraulics and support a capacitance–embolism risk trade-off. We further show that SCV_MD provides a practical proxy for hydraulic status where direct tensiometry is impractical, informing physiologically based forest management.

Graphical abstract