Abstract
Human-caused climate change is expected to bring more frequent and extended droughts with shorter wet periods of relief in between for many regions of the world. Critical knowledge gaps remain around the extent to which tree species can acclimate physiologically to repeated droughts. Using a common garden experiment with saplings of the widespread and ecologically important trembling aspen (Populus tremuloides), we studied how repeat drought and recovery treatments impact plant functional traits and physiological responses. We utilised four treatments over the course of 3 years: a continuous control, a three consecutive drought year treatment, a two consecutive drought year treatment, and a treatment with two drought years with a well-watered recovery year in between. Trees that experienced a recovery period between two drought treatments exhibited less drought resilience compared to both the two and three-consecutive-year treatments. Trees in the recovery treatment also exhibited lower growth rates and increased xylem damage in their older rings. Additionally, we observed no evidence of hydraulic acclimation to severe drought over time. These findings indicate that, during severe and repeated droughts, aspen saplings are likely to experience increases in hydraulic vulnerability, and wet periods between droughts are not likely to improve overall drought responses.
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Claims 5
Claim · model-written summary
A recovery year between two droughts gave trees less drought resilience than consecutive drought treatments.
Verbatim
e0“trembling aspen (Populus tremuloides)”
e1“Trees that experienced a recovery period between two drought treatments exhibited less drought resilience compared to both the two and three-consecutive-year treatments.”
Claim · model-written summary
Recovery treatment reduced tree growth rates.
Not reportedComparator
Verbatim
e0“trembling aspen (Populus tremuloides)”
e1“Trees in the recovery treatment also exhibited lower growth rates and increased xylem damage in their older rings.”
Claim · model-written summary
Recovery treatment increased xylem damage in older rings.
- Taxon
- trembling aspene0
- Organ / stage
- older ringse1
- Treatment
- recovery treatmente1
- Outcome
- xylem damagee1
- Direction
- increasede1
Not reportedComparator
Verbatim
e0“trembling aspen (Populus tremuloides)”
e1“Trees in the recovery treatment also exhibited lower growth rates and increased xylem damage in their older rings.”
Claim · model-written summary
No hydraulic acclimation to severe drought was detected over time.
Not reportedComparator
Verbatim
e0“trembling aspen (Populus tremuloides)”
e1“we observed no evidence of hydraulic acclimation to severe drought over time”
Claim · model-written summary
The authors infer severe repeated drought raises hydraulic vulnerability.
- Taxon
- trembling aspene0
- Treatment
- severe and repeated droughtse1
- Outcome
- hydraulic vulnerabilitye1
- Direction
- increasese1
- Qualifier
- likelye1
Not reportedComparator
Verbatim
e0“trembling aspen (Populus tremuloides)”
e1“during severe and repeated droughts, aspen saplings are likely to experience increases in hydraulic vulnerability”