Response to Comment on “Increased growing-season productivity drives earlier autumn leaf senescence in temperate trees”

Zani, Deborah; Crowther, Thomas W.; Mo, Lidong; Renner, Susanne S.; Zohner, Constantin M.

doi:10.1126/science.abg2679

Cited by 3 publications

(2 citation statements)

References 11 publications

(5 reference statements)

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“…Interestingly, we further found that the advancing rates of SOS were larger in northern semi-humid regions than southern humid regions where a larger delayed rate of EOS was found over the study period of 1982–2015. That might be because the vegetation in high-latitude regions is more sensitive to spring temperature variation, which is an adaptive protection mechanism in plants ( Prevéy et al, 2017 ), but the EOS might be more sensitive to light conditions and/or phycological growth cues ( Zani et al, 2020 , 2021 ). Overall, we found the extended GSL for river basins in the semi-humid region was mainly attributed to the earlier SOS, but the delayed EOS contributed mostly to the prolonged GSL for river basins in humid regions.…”

Section: Discussionmentioning

confidence: 99%

Influences of Shifted Vegetation Phenology on Runoff Across a Hydroclimatic Gradient

Chen

Geng

et al. 2022

Front. Plant Sci.

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Climate warming has changed vegetation phenology, and the phenology-associated impacts on terrestrial water fluxes remain largely unquantified. The impacts are linked to plant adjustments and responses to climate change and can be different in different hydroclimatic regions. Based on remote sensing data and observed river runoff of hydrological station from six river basins across a hydroclimatic gradient from northeast to southwest in China, the relative contributions of the vegetation (including spring and autumn phenology, growing season length (GSL), and gross primary productivity) and climatic factors affecting the river runoffs over 1982–2015 were investigated by applying gray relational analysis (GRA). We found that the average GSLs in humid regions (190–241 days) were longer than that in semi-humid regions (186–192 days), and the average GSLs were consistently extended by 4.8–13.9 days in 1982–2015 period in six river basins. The extensions were mainly linked to the delayed autumn phenology in the humid regions and to advanced spring phenology in the semi-humid regions. Across all river basins, the GRA results showed that precipitation (r = 0.74) and soil moisture (r = 0.73) determine the river runoffs, and the vegetation factors (VFs) especially the vegetation phenology also affected the river runoffs (spring phenology: r = 0.66; GSL: r = 0.61; autumn phenology: r = 0.59), even larger than the contribution from temperature (r = 0.57), but its relative importance is climatic region-dependent. Interestingly, the spring phenology is the main VF in the humid region for runoffs reduction, while both spring and autumn growth phenology are the main VFs in the semi-humid region, because large autumn phenology delay and less water supply capacity in spring amplify the effect of advanced spring phenology. This article reveals diverse linkages between climatic and VFs, and runoff in different hydroclimatic regions, and provides insights that vegetation phenology influences the ecohydrology process largely depending on the local hydroclimatic conditions, which improve our understanding of terrestrial hydrological responses to climate change.

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Section: Discussionmentioning

confidence: 99%

Influences of Shifted Vegetation Phenology on Runoff Across a Hydroclimatic Gradient

Chen

Geng

et al. 2022

Front. Plant Sci.

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“…While the relationship of tree C source–sink dynamics and leaf senescence has received less attention than herbaceous plants, there are indications that a higher C source activity in trees (e.g., due to more leaves or earlier leaf‐out) can be followed by earlier autumn leaf senescence (Fu et al, 2014 ; Zani et al, 2020 ). However, delayed or unchanged senescence under e[CO 2 ] from multiple CO 2 enrichment studies (Herrick & Thomas, 2003 ; Norby et al, 2003 ; Taylor et al, 2008 ) provides alternative expectations (Norby, 2021 ; Zani et al, 2021 ). If the C source–sink balance proves to be a general driver of autumnal leaf senescence, it will be even more important for calculations of future terrestrial C fluxes to not only consider exogenous factors like nutrient or water availability.…”

Section: Physiologymentioning

confidence: 99%

Links across ecological scales: Plant biomass responses to elevated CO₂

Maschler

Bialic‐Murphy

Wan

et al. 2022

Global Change Biology

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The degree to which elevated CO 2 concentrations (e[CO 2 ]) increase the amount of carbon (C) assimilated by vegetation plays a key role in climate change. However, due to the short-term nature of CO 2 enrichment experiments and the lack of reconciliation between different ecological scales, the effect of e[CO 2 ] on plant biomass stocks remains a major uncertainty in future climate projections. Here, we review the effect of e[CO 2 ] on plant biomass across multiple levels of ecological organization, scaling from physiological responses to changes in population-, community-, ecosystem-, and global-scale dynamics. We find that evidence for a sustained biomass response to e[CO 2 ] varies across ecological scales, leading to diverging conclusions about the responses of individuals, populations, communities, and ecosystems. While the distinct focus of every scale reveals new mechanisms driving biomass accumulation under e[CO 2 ], none of them provides a full picture of all relevant processes. For example,This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Process-oriented models of autumn leaf phenology: ways to sound calibration and implications of uncertain projections

Meier,

Bigler

2023

Geosci. Model Dev.

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Abstract. Autumn leaf phenology marks the end of the growing season, during which trees assimilate atmospheric CO2. The length of the growing season is affected by climate change because autumn phenology responds to climatic conditions. Thus, the timing of autumn phenology is often modeled to assess possible climate change effects on future CO2-mitigating capacities and species compositions of forests. Projected trends have been mainly discussed with regards to model performance and climate change scenarios. However, there has been no systematic and thorough evaluation of how performance and projections are affected by the calibration approach. Here, we analyzed >2.3 million performances and 39 million projections across 21 process-oriented models of autumn leaf phenology, 5 optimization algorithms, ≥7 sampling procedures, and 26 climate model chains from two representative concentration pathways. Calibration and validation were based on >45 000 observations for beech, oak, and larch from 500 central European sites each. Phenology models had the largest influence on model performance. The best-performing models were (1) driven by daily temperature, day length, and partly by seasonal temperature or spring leaf phenology; (2) calibrated with the generalized simulated annealing algorithm; and (3) based on systematically balanced or stratified samples. Autumn phenology was projected to shift between −13 and +20 d by 2080–2099 compared to 1980–1999. Climate scenarios and sites explained more than 80 % of the variance in these shifts and thus had an influence 8 to 22 times greater than the phenology models. Warmer climate scenarios and better-performing models predominantly projected larger backward shifts than cooler scenarios and poorer models. Our results justify inferences from comparisons of process-oriented phenology models to phenology-driving processes, and we advocate for species-specific models for such analyses and subsequent projections. For sound calibration, we recommend a combination of cross-validations and independent tests, using randomly selected sites from stratified bins based on mean annual temperature and average autumn phenology, respectively. Poor performance and little influence of phenology models on autumn phenology projections suggest that current models are overlooking relevant drivers. While the uncertain projections indicate an extension of the growing season, further studies are needed to develop models that adequately consider the relevant processes for autumn phenology.

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Response to Comment on “Increased growing-season productivity drives earlier autumn leaf senescence in temperate trees”

Cited by 3 publications

References 11 publications

Influences of Shifted Vegetation Phenology on Runoff Across a Hydroclimatic Gradient

Influences of Shifted Vegetation Phenology on Runoff Across a Hydroclimatic Gradient

Links across ecological scales: Plant biomass responses to elevated CO₂

Process-oriented models of autumn leaf phenology: ways to sound calibration and implications of uncertain projections

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Response to Comment on “Increased growing-season productivity drives earlier autumn leaf senescence in temperate trees”

Cited by 3 publications

References 11 publications

Influences of Shifted Vegetation Phenology on Runoff Across a Hydroclimatic Gradient

Influences of Shifted Vegetation Phenology on Runoff Across a Hydroclimatic Gradient

Links across ecological scales: Plant biomass responses to elevated CO2

Process-oriented models of autumn leaf phenology: ways to sound calibration and implications of uncertain projections

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Product

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Links across ecological scales: Plant biomass responses to elevated CO₂