Photosynthetic and hydraulic traits influence forest resistance and resilience to drought stress across different biomes

Hu, Yukun; Xiang, Wenhua; Schäfer, K. V.; Deng, Xiaomin; Forrester, David I.; Fang, Xi; Zeng, Yelin; Ouyang, Shuai; Chen, Liang; Peng, Changhui

doi:10.1016/j.scitotenv.2022.154517

Cited by 13 publications

(8 citation statements)

References 95 publications

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“…Forests in arid/semi-arid regions (with high mean VPD) like the broadleaf forests (angiosperms) in this study usually benefited from a "hydraulic safety system" which is characterized by high hydraulic safety margins (HSMs) but less strict stomatal regulation (Hacke et al, 2017;Oliveira et al, 2021). On the contrary, forest species growing in less dry regions (with low mean VPD) consisted mostly of gymnosperms with a "hydraulic efficiency system" characterized by lower HSMs but a stricter stomatal regulation (Flo et al, 2021;Hu et al, 2022).…”

Section: Forest Response To Extreme Atmospheric Drynessmentioning

confidence: 79%

“…Forests in arid/semi‐arid regions (with high mean VPD) like the broadleaf forests (angiosperms) in this study usually benefited from a “hydraulic safety system” which is characterized by high hydraulic safety margins (HSMs) but less strict stomatal regulation (Hacke et al, 2017; Oliveira et al, 2021). On the contrary, forest species growing in less dry regions (with low mean VPD) consisted mostly of gymnosperms with a “hydraulic efficiency system” characterized by lower HSMs but a stricter stomatal regulation (Flo et al, 2021; Hu et al, 2022). What characterizes a lower HSM in gymnosperms is the higher diameter of xylem tracheid (less tolerant to low leaf water potentials and more susceptible to embolism), combined with larger stomatal closure at less negative leaf water potentials and thus lower CO 2 uptake (Chen et al, 2021; Hacke et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

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Long‐term changes in forest response to extreme atmospheric dryness

Shekhar

Hörtnagl

Buchmann

et al. 2023

Global Change Biology

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Atmospheric dryness, as indicated by vapor pressure deficit (VPD), has a strong influence on forest greenhouse gas exchange with the atmosphere. In this study, we used long‐term (10–30 years) net ecosystem productivity (NEP) measurements from 60 forest sites across the world (1003 site‐years) to quantify long‐term changes in forest NEP resistance and NEP recovery in response to extreme atmospheric dryness. We tested two hypotheses: first, across sites differences in NEP resistance and NEP recovery of forests will depend on both the biophysical characteristics (i.e., leaf area index [LAI] and forest type) of the forest as well as on the local meteorological conditions of the site (i.e., mean VPD of the site), and second, forests experiencing an increasing trend in frequency and intensity of extreme dryness will show an increasing trend in NEP resistance and NEP recovery over time due to emergence of long‐term ecological stress memory. We used a data‐driven statistical learning approach to quantify NEP resistance and NEP recovery over multiple years. Our results showed that forest types, LAI, and median local VPD conditions explained over 50% of variance in both NEP resistance and NEP recovery, with drier sites showing higher NEP resistance and NEP recovery compared to sites with less atmospheric dryness. The impact of extreme atmospheric dryness events on NEP lasted for up to 3 days following most severe extreme events in most forests, indicated by an NEP recovery of less than 100%. We rejected our second hypothesis as we found no consistent relationship between trends of extreme VPD with trends in NEP resistance and NEP recovery across different forest sites, thus an increase in atmospheric dryness as it is predicted might not increase the resistance or recovery of forests in terms of NEP.

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Section: Forest Response To Extreme Atmospheric Drynessmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Long‐term changes in forest response to extreme atmospheric dryness

Shekhar

Hörtnagl

Buchmann

et al. 2023

Global Change Biology

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“…Our results also indicated that forest was the most sensitive to radiative effects among the GPP estimates based on the vegetation index. Due to the deep root systems of trees, forest can use water more conservatively during droughts and maintain normal photosynthesis longer during droughts than can other ecosystems (Hu et al., 2022; Zhang et al., 2016). Records based on site observations also showed that the negative anomaly value of forest GPP was the smallest among the vegetation types during droughts.…”

Section: Discussionmentioning

confidence: 99%

Vegetation Index‐Based Models Without Meteorological Constraints Underestimate the Impact of Drought on Gross Primary Productivity

Chen,

Liu

et al. 2024

JGR Biogeosciences

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Recently developed solar‐induced chlorophyll fluorescence‐related vegetation indices (e.g., near infrared reflectance of vegetation (NIRv) and kernel normalized difference vegetation index (kNDVI)) have been reported to be appropriate proxies for vegetation photosynthesis. These vegetation indices can be used to estimate gross primary productivity (GPP) without considering meteorological constraints. However, it is not clear whether such a statement holds true under various environmental conditions. In this study, we explored whether these vegetation indices require meteorological constraints to better characterize GPP under extreme drought conditions using three extreme drought cases in Europe in 2003, 2010, and 2018. According to the long‐term series of observations, vegetation indices (NIRv and kNDVI) alone explained 60% and 57%, respectively, of the weekly GPP variation across the 66 flux sites. The explained variation increased to 69% and 64%, respectively, for the models that take into account radiative effects (NIRv and kNDVI multiplied by radiation). However, without considering meteorological constraints, these vegetation index‐based estimations severely underestimated negative GPP anomalies under drought stress, especially in models that incorporate radiative effects. After incorporating vapor pressure deficit (VPD)‐based meteorological constraints, the GPP estimations exhibited more pronounced negative anomalies during drought periods while maintaining model accuracy (at 70% and 65%, respectively). In addition, the GPP models based on site observations were applied at the regional scale (Europe). Our results indicated that the models without meteorological constraints again underestimated the impact of drought on GPP. This study emphasizes the importance of meteorological constraints in the estimation of GPP, especially under extreme drought conditions.

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“…As a result, this poses a great challenge to the conservation of rainforests. The photosynthetic and hydraulic characteristics of forests influence resistance and resilience to drought stress across a wide range of ecosystems, and the diversity of functional traits has been shown to affect forests' resilience to drought stress [4,5]. Thus, preserving the diversity of the functional traits of rainforests is important.…”

Section: Introductionmentioning

confidence: 99%

Seasonal Patterns and Species Variability in the Leaf Traits of Dominant Plants in the Tropical Rainforests of Hainan Island, China

Qiu

Nong

et al. 2023

Forests

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The leaf traits measured in multiple species are known to vary between seasons, but there is a knowledge gap relating to the seasonal variability and environmental adaptation of plants in tropical rainforests. To investigate the dynamics of the functional traits of dominant species in tropical rainforests and the differences in their adaptation strategies to seasonal drought, the results of this study can provide a scientific basis for tropical rainforest conservation resource protection. Six dominant species, including three trees (Hopea reticulata, Vatica mangachapoi, and Diospyros chunii) and three vine plants (Ancistrocladus tectorius, Phanera khasiana, and Uvaria sanyaensis), in tropical lowland rainforest in the Ganzaling Nature Reserve of Hainan province were selected as study objectives. The key leaf traits were studied using the paraffin section method, leaf epidermis segregation method, and Li-6400 portable photosynthesis system in June, September, December, 2019, and March, 2020. Results showed that significant differences in photosynthetic physiology and morphological and structural parameters among species, as well as seasonal variability, were observed in leaf photosynthetic physiology, but not in leaf morphological or structural parameters. A phenotypic plasticity index (PPI) analysis revealed more variability in leaf photosynthetic physiology (Average PPI = 0.37) than in leaf anatomical structure and morphology (Average PPI = 0.26), suggesting that they adapt to seasonal changes primarily by regulating photosynthetic physiological parameters rather than leaf morphology or anatomical structure. The dominant trees were found to have higher water use efficiency, leaf dry-matter content, and smaller leaf areas compared to vine plants. This indicates that the dominant tree species depend on high water use efficiency and leaf morphological characteristics to adapt to seasonal changes. The majority of leaf anatomical structure parameters associated with drought tolerance were higher in the three dominant vine species, indicating that the dominant vine species adapted to drought stress primarily by altering the leaf anatomical structure This study provides information on how tropical rainforest plants adapt to seasonal drought as well as supporting the protection of tropical rainforest ecosystems.

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Photosynthetic and hydraulic traits influence forest resistance and resilience to drought stress across different biomes

Cited by 13 publications

References 95 publications

Long‐term changes in forest response to extreme atmospheric dryness

Long‐term changes in forest response to extreme atmospheric dryness

Vegetation Index‐Based Models Without Meteorological Constraints Underestimate the Impact of Drought on Gross Primary Productivity

Seasonal Patterns and Species Variability in the Leaf Traits of Dominant Plants in the Tropical Rainforests of Hainan Island, China

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