Monitoring the impact of aerosol contamination on the drought-induced decline of gross primary productivity

AbstractGiven their high carbon uptake, the terrestrial ecosystems in the East Asia summer monsoon (EASM) region play an irreplaceable role in the global carbon cycle. Because the rich vegetation growth over East Asia benefits mainly from the sufficient water supply brought by the EASM, which is characterized by a strong intraseasonal oscillation (ISO), the intraseasonal spatiotemporal variations and underlying drivers of photosynthesis activity over East Asia have been comprehensively investigated using the daily gross primary productivity (GPP) and meteorological data. Strong intraseasonal fluctuations of GPP have been identified over the area between the Yangtze and Yellow Rivers (YYR) with a magnitude of 0.4 gC m−2 day−1. The mean power spectrum suggests that 20–50-day variation is the major component of the intraseasonal GPP anomalies over the YYR during the summers of 1980–2013. The 20–50-day ISO of YYR GPP anomalies is modulated by the local 20–50-day precipitation variation via soil moisture, with precipitation (soil moisture) leading GPP by 10 (7) days. The 20–50-day YYR precipitation anomalies are in turn controlled by tropical ISO signals, particularly the convective activity over the western North Pacific. This leading relationship between the 20–50-day atmospheric ISO and GPP suggests a potential for extended-range predictability of vegetation growth.

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Response of savanna gross primary productivity to interannual variability in rainfall

Progress in Physical Geography Earth and Environment ◽

10.1177/0309133313490006 ◽

2013 ◽

Vol 37 (5) ◽

pp. 642-663 ◽

Cited By ~ 22

Author(s):

Kasturi Devi Kanniah ◽

Jason Beringer ◽

Lindsay B. Hutley

Keyword(s):

Interannual Variability ◽

Primary Productivity ◽

Environmental Changes ◽

Gross Primary Productivity ◽

Arid Ecosystems ◽

Annual Rainfall ◽

Strong Positive Correlation ◽

Regional Budget ◽

Closed Forest ◽

The Impact

Studying the temporal pattern of savanna gross primary productivity (GPP) is essential for predicting the response of the biome to global environmental changes. In this study, MODIS satellite data coupled with eddy covariance based flux measurements were used to estimate GPP using a remote sensing based light use efficiency model across a significant rainfall gradient in the Northern Territory (NT) region of Australia. Closed forest that occurred in wet and often fireproof environments assimilated (GPP) 4–6 times more carbon than grasslands and Acacia woodlands that grow in arid environments (<600 mm annual rainfall). However, due to their small spatial extent, closed forests contributed <0.5% of the regional budget compared to savanna woodlands (86%) and grasslands (32%). Annual rainfall was found to exert a significant influence on GPP for different vegetation types except for closed forest which was less sensitive to above-average rainfall. Interannual variability in GPP showed that arid ecosystems had a higher variation (>20%) compared to woodlands and forest (∼5%). This variation in GPP was correlated with that of rainfall (R2 = 0.88, p<0.05). Analysis of the impact of wettest and driest years on GPP showed a strong positive correlation between the magnitude of the relative maxima in rainfall and maxima in GPP (R2 = 0.89, p<0.05). In contrast, the relative rainfall minima exhibited an insignificant relationship with relative GPP minima (R2 = 0.45, p = 0.07). These findings provide valuable information on the carbon uptake across the savanna biome and show the sensitivity of different vegetation systems to rainfall, a variable that may change in quantity and variability with projected climate change. Such data also show regions of high levels of carbon that could be linked with savanna management to protect the resources in the Australian savannas.

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Ozone-induced gross primary productivity reductions over European forests inferred from satellite observations

10.5194/bg-2021-125 ◽

2021 ◽

Author(s):

Jasdeep Singh Anand ◽

Alessandro Anav ◽

Marcello Vitale ◽

Daniele Peano ◽

Nadine Unger ◽

...

Keyword(s):

Soil Moisture ◽

Primary Productivity ◽

Land Surface ◽

Gross Primary Productivity ◽

Significant Variable ◽

Terrestrial Carbon ◽

European Forests ◽

The Mediterranean ◽

The Impact

Abstract. Tropospheric O3 damages leaves and directly inhibits photosynthesis, posing a threat to terrestrial carbon sinks. Previous investigations have mostly relied on sparse in-situ data or simulations using land surface models. This work is the first to use satellite data to quantify the effect of O3 exposure on gross primary productivity (GPP). O3-induced GPP reductions were estimated to vary between 0.36–9.55% across European forests along a North-South transect between 2003–2015, in line with prior estimates. No significant temporal trend could be determined over most of Europe, while Random Forest analysis (RFA) shows that soil moisture is a significant variable governing GPP reductions over the Mediterranean. Comparisons between this work and GPP reductions simulated by the Yale Interactive Biosphere (YIBs) model suggest that satellite-based estimates over the Mediterranean region may be biased by +12%, potentially because of differences in modelling stomatal sensitivity to soil moisture and prior O3 exposure. This work has demonstrated for the first time that satellite-based datasets can be leveraged to assess the impact of O3 on the terrestrial carbon sink, which are comparable with in-situ or model-based analyses.

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Non-stomatal processes reduce gross primary productivity in temperate forest ecosystems during severe edaphic drought

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2019.0527 ◽

2020 ◽

Vol 375 (1810) ◽

pp. 20190527 ◽

Cited By ~ 4

Author(s):

Louis Gourlez de la Motte ◽

Quentin Beauclaire ◽

Bernard Heinesch ◽

Mathias Cuntz ◽

Lenka Foltýnová ◽

...

Keyword(s):

Primary Productivity ◽

Temperate Forest ◽

Forest Ecosystems ◽

Stomatal Closure ◽

Gross Primary Productivity ◽

Severe Drought ◽

Continental Scale ◽

European Forest ◽

Ecosystem Flux ◽

The Impact

Severe drought events are known to cause important reductions of gross primary productivity ( GPP ) in forest ecosystems. However, it is still unclear whether this reduction originates from stomatal closure (Stomatal Origin Limitation) and/or non-stomatal limitations (Non-SOL). In this study, we investigated the impact of edaphic drought in 2018 on GPP and its origin (SOL, NSOL) using a dataset of 10 European forest ecosystem flux towers. In all stations where GPP reductions were observed during the drought, these were largely explained by declines in the maximum apparent canopy scale carboxylation rate V CMAX,APP (NSOL) when the soil relative extractable water content dropped below around 0.4. Concurrently, we found that the stomatal slope parameter ( G 1 , related to SOL) of the Medlyn et al . unified optimization model linking vegetation conductance and GPP remained relatively constant. These results strengthen the increasing evidence that NSOL should be included in stomatal conductance/photosynthesis models to faithfully simulate both GPP and water fluxes in forest ecosystems during severe drought. This article is part of the theme issue ‘Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale’.

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Mapping the reduction in gross primary productivity in subarctic birch forests due to insect outbreaks

Biogeosciences ◽

10.5194/bg-14-1703-2017 ◽

2017 ◽

Vol 14 (6) ◽

pp. 1703-1719 ◽

Cited By ~ 10

Author(s):

Per-Ola Olsson ◽

Michal Heliasz ◽

Hongxiao Jin ◽

Lars Eklundh

Keyword(s):

Spatial Resolution ◽

Primary Productivity ◽

Gross Primary Productivity ◽

Birch Forest ◽

High Temporal Resolution ◽

Forest Disturbances ◽

Insect Outbreaks ◽

Substantial Impact ◽

The Impact ◽

Birch Forests

Abstract. It is projected that forest disturbances, such as insect outbreaks, will have an increasingly negative impact on forests with a warmer climate. These disturbance events can have a substantial impact on forests' ability to absorb atmospheric CO2, and may even turn forests from carbon sinks into carbon sources; hence, it is important to develop methods both to monitor forest disturbances and to quantify the impact of these disturbance events on the carbon balance. In this study we present a method to monitor insect-induced defoliation in a subarctic birch forest in northern Sweden, and to quantify the impact of these outbreaks on gross primary productivity (GPP). Since frequent cloud cover in the study area requires data with high temporal resolution and limits the use of finer spatial resolution sensors such as Landsat, defoliation was mapped with remote sensing data from the MODIS sensor with 250 m  ×  250 m spatial resolution. The impact on GPP was estimated with a light use efficiency (LUE) model that was calibrated with GPP data obtained from eddy covariance (EC) measurements from 5 years with undisturbed birch forest and 1 year with insect-induced defoliation. Two methods were applied to estimate the impact on GPP: (1) applying a GPP reduction factor derived from EC measured GPP to estimate GPP loss, and (2) running a LUE model for both undisturbed and defoliated forest and deriving the differences in modelled GPP. In the study area of 100 km2 the results suggested a substantial setback to the carbon uptake: an average decrease in regional GPP over the three outbreak years (2004, 2012, and 2013) was estimated to 15 ± 5 Gg C yr−1, compared to the mean regional GPP of 40 ± 12 Gg C yr−1 for the 5 years without defoliation, i.e. 38 %. In the most severe outbreak year (2012), 76 % of the birch forests were defoliated, and annual regional GPP was merely 50 % of GPP for years without disturbances. The study has generated valuable data on GPP reduction, and demonstrates a potential for mapping insect disturbance impact over extended areas.

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Distinct response of gross primary productivity in five terrestrial biomes to precipitation variability

Communications Earth & Environment ◽

10.1038/s43247-020-00034-1 ◽

2020 ◽

Vol 1 (1) ◽

Author(s):

François Ritter ◽

Max Berkelhammer ◽

Cynthia Garcia-Eidell

Keyword(s):

Primary Productivity ◽

Rainfall Variability ◽

Precipitation Variability ◽

Gross Primary Productivity ◽

Global Network ◽

Annual Rainfall ◽

Terrestrial Carbon ◽

Interannual Rainfall Variability ◽

Daily Precipitation Data ◽

The Impact

Abstract Climate change will impact precipitation variability, potentially accelerating climate-terrestrial carbon feedbacks. However, the response of ecosystems to precipitation variability is difficult to constrain due to myriad physiological and abiotic variables that limit terrestrial productivity. Based on a combination of satellite imagery and a global network of daily precipitation data, we present here a statistical framework to isolate the impact of precipitation variability on the gross primary productivity of five biomes that collectively account for 50% of global land area. The productivity of mesic grasslands and forests decreases by ~28% and ~7% (respectively) in response to more irregular rain within the year, while the sensitivity is halved in response to higher year-to-year variability. Xeric grasslands are similarly impacted by intra-annual rainfall variance, but they show an increase in productivity with higher interannual rainfall variability. Conversely, the productivity of boreal forests increases under higher variability on both timescales. We conclude that projected changes in precipitation variability will have a measurable global impact on the terrestrial carbon sink.

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