Earlier springs decrease peak summer productivity in North American boreal forests
Reads0
Chats0
TLDR
In this paper, the authors analyzed nearly three decades (1982?2008) of observational records and derived products, including satellite microwave and optical imagery as well as upscaled ecosystem flux observations, to better understand how shifts in seasonality impact hydrology and productivity in the North American boreal forests.Abstract:
In the northern high latitudes, alternative hypotheses with regards to how warming-related shifts in seasonality influence ecosystem productivity exist. Increased plant growth associated with a longer growing season may enhance ecosystem productivity, but shifts to earlier springs may also negatively influence soil moisture status and productivity during the peak of the growing season. Here, we analyzed nearly three decades (1982?2008) of observational records and derived products, including satellite microwave and optical imagery as well as upscaled ecosystem flux observations, to better understand how shifts in seasonality impact hydrology and productivity in the North American boreal forests. We identified a dominant adverse influence of earlier springs on peak summer forest greenness, actual evapotranspiration and productivity at interannual time scales across the drier western and central sections of the North American boreal forests. In the vast regions where this spring onset mechanism operates, ecosystem productivity gains from earlier springs during the early portion of the growing season are effectively cancelled through corresponding losses in the later portion. Our results also indicate that recent decadal shifts towards earlier springs and associated drying in the midst of the growing season over western North American boreal forests may have contributed to the reported declines in summer productivity and increases in tree mortality and fire activity. With projections of accelerated northern high-latitude warming and associated shifts to earlier springs, persistent soil moisture deficits in peak summer may be an effective mechanism for regional-scale boreal forest dieback through their strong influence on productivity, tree mortality and disturbance dynamics.read more
Citations
More filters
Global patterns of land-atmosphere fluxes of carbon dioxide, latent heat, and sensible heat derived from eddy covariance, satellite, and meteorological observations
Abstract: We upscaled FLUXNET observations of carbon dioxide, water, and energy fluxes to the global scale using the machine learning technique, model tree ensembles (MTE). We trained MTE to predict site-level gross primary productivity (GPP), terrestrial ecosystem respiration (TER), net ecosystem exchange (NEE), latent energy (LE), and sensible heat (H) based on remote sensing indices, climate and meteorological data, and information on land use. We applied the trained MTEs to generate global flux fields at a 0.5 degrees x 0.5 degrees spatial resolution and a monthly temporal resolution from 1982 to 2008. Cross-validation analyses revealed good performance of MTE in predicting among-site flux variability with modeling efficiencies (MEf) between 0.64 and 0.84, except for NEE (MEf = 0.32). Performance was also good for predicting seasonal patterns (MEf between 0.84 and 0.89, except for NEE (0.64)). By comparison, predictions of monthly anomalies were not as strong (MEf between 0.29 and 0.52). Improved accounting of disturbance and lagged environmental effects, along with improved characterization of errors in the training data set, would contribute most to further reducing uncertainties. Our global estimates of LE (158 +/- 7 J x 10(18) yr(-1)), H (164 +/- 15 J x 10(18) yr(-1)), and GPP (119 +/- 6 Pg C yr(-1)) were similar to independent estimates. Our global TER estimate (96 +/- 6 Pg C yr(-1)) was likely underestimated by 5-10%. Hot spot regions of interannual variability in carbon fluxes occurred in semiarid to semihumid regions and were controlled by moisture supply. Overall, GPP was more important to interannual variability in NEE than TER. Our empirically derived fluxes may be used for calibration and evaluation of land surface process models and for exploratory and diagnostic assessments of the biosphere.
Journal ArticleDOI
Plant phenology and global climate change: Current progresses and challenges
Shilong Piao,Shilong Piao,Qiang Liu,Anping Chen,Ivan A. Janssens,Yongshuo H. Fu,Yongshuo H. Fu,Junhu Dai,Lingli Liu,Xu Lian,Miaogen Shen,Xiaolin Zhu +11 more
TL;DR: It is suggested that future studies should primarily focus on using new observation tools to improve the understanding of tropical plant phenology, on improving process-based phenology modeling, and on the scaling of phenology from species to landscape-level.
Journal ArticleDOI
Net carbon uptake has increased through warming-induced changes in temperate forest phenology
Trevor F. Keenan,Trevor F. Keenan,Josh M. Gray,Mark A. Friedl,Michael Toomey,Gil Bohrer,David Y. Hollinger,J. William Munger,John O'Keefe,Hans Peter Schmid,Ian Sue Wing,Bai Yang,Andrew D. Richardson +12 more
TL;DR: In the case of an earlier spring and a later autumn, carbon uptake (photosynthesis) increases considerably more than carbon release (respiration) in temperate forests in the eastern US as mentioned in this paper.
Net Carbon Uptake Has Increased through Warming-Induced Changes in Temperate Forest Phenology
Trevor F. Keenan,Andrew D. Richardson,Josh M. Gray,Mark A. Friedl,Michael Toomey,Gil Bohrer,David Y. Hollinger,J. W. Munger,Hans Peter Schmid,I. Sue Wing,B. Yang +10 more
Journal ArticleDOI
Delayed autumn phenology in the Northern Hemisphere is related to change in both climate and spring phenology.
Qiang Liu,Yongshuo H. Fu,Yongshuo H. Fu,Zaichun Zhu,Yongwen Liu,Zhuo Liu,Mengtian Huang,Ivan A. Janssens,Shilong Piao,Shilong Piao,Shilong Piao +10 more
TL;DR: In this paper, the temporal correlations between EOS and environmental factors (i.e., temperature, precipitation and insolation), as well as the correlation between spring and autumn phenology, using partial correlation analyses were determined.
References
More filters
Global patterns of land-atmosphere fluxes of carbon dioxide, latent heat, and sensible heat derived from eddy covariance, satellite, and meteorological observations
Abstract: We upscaled FLUXNET observations of carbon dioxide, water, and energy fluxes to the global scale using the machine learning technique, model tree ensembles (MTE). We trained MTE to predict site-level gross primary productivity (GPP), terrestrial ecosystem respiration (TER), net ecosystem exchange (NEE), latent energy (LE), and sensible heat (H) based on remote sensing indices, climate and meteorological data, and information on land use. We applied the trained MTEs to generate global flux fields at a 0.5 degrees x 0.5 degrees spatial resolution and a monthly temporal resolution from 1982 to 2008. Cross-validation analyses revealed good performance of MTE in predicting among-site flux variability with modeling efficiencies (MEf) between 0.64 and 0.84, except for NEE (MEf = 0.32). Performance was also good for predicting seasonal patterns (MEf between 0.84 and 0.89, except for NEE (0.64)). By comparison, predictions of monthly anomalies were not as strong (MEf between 0.29 and 0.52). Improved accounting of disturbance and lagged environmental effects, along with improved characterization of errors in the training data set, would contribute most to further reducing uncertainties. Our global estimates of LE (158 +/- 7 J x 10(18) yr(-1)), H (164 +/- 15 J x 10(18) yr(-1)), and GPP (119 +/- 6 Pg C yr(-1)) were similar to independent estimates. Our global TER estimate (96 +/- 6 Pg C yr(-1)) was likely underestimated by 5-10%. Hot spot regions of interannual variability in carbon fluxes occurred in semiarid to semihumid regions and were controlled by moisture supply. Overall, GPP was more important to interannual variability in NEE than TER. Our empirically derived fluxes may be used for calibration and evaluation of land surface process models and for exploratory and diagnostic assessments of the biosphere.
Journal ArticleDOI
Global patterns of land-atmosphere fluxes of carbon dioxide, latent heat, and sensible heat derived from eddy covariance, satellite, and meteorological observations
Martin Jung,Markus Reichstein,Hank A. Margolis,Alessandro Cescatti,Andrew D. Richardson,M. Altaf Arain,Almut Arneth,Almut Arneth,Christian Bernhofer,Damien Bonal,Jiquan Chen,Damiano Gianelle,Nadine Gobron,Gerald Kiely,Werner L. Kutsch,Gitta Lasslop,Beverly E. Law,Anders Lindroth,Lutz Merbold,Leonardo Montagnani,Leonardo Montagnani,Eddy Moors,Dario Papale,Matteo Sottocornola,Francesco Primo Vaccari,Christopher B. Williams +25 more
TL;DR: In this paper, the authors upscaled FLUXNET observations of carbon dioxide, water, and energy fluxes to the global scale using the machine learning technique, model tree ensembles (MTE), to predict site-level gross primary productivity (GPP), terrestrial ecosystem respiration (TER), net ecosystem exchange (NEE), latent energy (LE), and sensible heat (H) based on remote sensing indices, climate and meteorological data, and information on land use.
Journal ArticleDOI
Recent changes in the fire regime across the North American boreal region—Spatial and temporal patterns of burning across Canada and Alaska
TL;DR: Recently, Kasischke et al. as mentioned in this paper studied changes in the fire regime across the North American boreal region (NABR) and found that the proportion of total burned area from human-ignited fires decreased over this same time period.
Journal ArticleDOI
A drought-induced pervasive increase in tree mortality across Canada's boreal forests
Changhui Peng,Changhui Peng,Zhihai Ma,Xiangdong Lei,Xiangdong Lei,Qiuan Zhu,Qiuan Zhu,Huai Chen,Huai Chen,Weifeng Wang,Shirong Liu,Weizhong Li,Weizhong Li,Xiuqin Fang,Xiaolu Zhou +14 more
TL;DR: In this article, a study using long-term forest plots now provides a quantitative estimate of drought-induced increase in tree mortality across Canada's boreal forests, one of the most important terrestrial carbon sinks.
Journal ArticleDOI
Satellite-observed photosynthetic trends across boreal North America associated with climate and fire disturbance
TL;DR: Stochastic changes across the time series were predominantly associated with a frequent and increasing fire disturbance regime and have implications for the direction of feedbacks to the climate system and emphasize the importance of longer term synoptic observations of arctic and boreal biomes.
Related Papers (5)
Influence of spring and autumn phenological transitions on forest ecosystem productivity
Andrew D. Richardson,T. Andy Black,Philippe Ciais,Nicolas Delbart,Mark A. Friedl,Nadine Gobron,David Y. Hollinger,Werner L. Kutsch,Bernard Longdoz,Sebastiaan Luyssaert,Sebastiaan Luyssaert,Mirco Migliavacca,Leonardo Montagnani,Leonardo Montagnani,J. William Munger,Eddy Moors,Shilong Piao,Corinna Rebmann,Markus Reichstein,Nobuko Saigusa,Enrico Tomelleri,Rodrigo Vargas,Andrej Varlagin +22 more