Embolism resistance explains mortality and recovery of five subtropical evergreen broadleaf trees to persistent drought

Abstract

Subtropical evergreen broadleaf forests (SEBF) are experiencing and expected to suffer more frequent and severe drought events. However, how the hydraulic traits directly link to the mortality and recovery of SEBF trees remains unclear. In this study, we conducted a drought-rewatering experiment on tree seedlings of five dominant species to investigate how the hydraulic traits were related to tree mortality and the resistance and recovery of photosynthesis (A) and transpiration (E) under different drought severities. Species with greater embolism resistance (P 50 ) survived longer than those with a weaker P 50 . However, there was no general hydraulic threshold associated with tree mortality, with the lethal hydraulic failure varying from 64% to 93% loss of conductance. The photosynthesis and transpiration of tree species with a greater P 50 were more resistant to and recovered faster from drought than those with lower P 50 . Other plant traits could not explain the interspecific variation in tree mortality and drought resistance and recovery. These results highlight the unique importance of embolism resistance in driving carbon and water processes under persistent drought across different trees in SEBFs. The absence of multiple efficient drought strategies in SEBF seedlings implies the difficulty of natural seedling regeneration under future droughts, which often occurs after destructive disturbances (e.g., extreme drought events and typhoon),

Hydraulic Traits and Non-Structural Carbon Responses to Drought Stress in Reaumuria soongorica (Pall.) Maxim. and Salsola passerina Bunge

“…The magnitude of P 50 , which represents the embolism resistance of plants [1,49], and HSM, which can predict species mortality [1,7,50], are important parameters in assessing plant responses to drought. It has been established in previous studies that species with lower P 50 values and higher HSM 50 values exhibit higher resistance to exogenous stresses and have longer survival rates [51,52]. Here, P 50 values for both R. soongorica and S. passerina were significantly higher under the chronic and flash drought treatments compared to the control (Figure 2D), indicating that drought reduces the plants' ability to resist embolization.…”

Response of Hydraulic and Photosynthetic Characteristics of Caroxylon passerinum (Bunge) Akhani and Roalson to Prolonged Drought and Short-Term Rehydration

“…The magnitude of P 50 can reflect the embolic resistance of plants [9,33]. Generally, species with low P 50 are more resistant to damage from exogenous stresses and plants survive longer [34,35]. We found that after drought treatment, compared with the control, although there was no significant change in embolism resistance in the 2 drought groups, the values increased with the intensity of drought stress, indicating that the stronger the drought stress, the weaker the embolism resistance of the stems.…”

Rainfall and topographic position determine tree embolism resistance in Amazônia and Cerrado sites

“…embolism). Lower (more negative) values of P 50 have been associated with higher resistance to drought and less mortality [53][54][55]. We measured P 50 in dominant trees in valleys and hills for three sites in South America, spanning a rainfall gradient from 1370 to 2245 mm yr −1 associated with an increase in dry season length and intensity.…”