Yitong Yao

California Institute of Technology | CIT · ESE

The future evolution of the Amazon rainforest remains uncertain not only due to uncertain climate projections, but also owing to the intricate balance between tree growth and mortality. Many Earth System Models inadequately represent forest demography processes, especially drought‐induced tree mortality. In this study, we used ORCHIDEE‐CAN‐NHA, a l...

In the framework of the RECCAP2 initiative, we present the greenhouse gas (GHG) and carbon (C) budget of Europe. For the decade of the 2010s, we present a bottom‐up (BU) estimate of GHG net‐emissions of 3.9 Pg CO2‐eq. yr⁻¹ (using a global warming potential on a 100 years horizon), which are largely dominated by fossil fuel emissions. In this decade...

The Amazon rainforest plays a crucial role in global carbon storage, but a minor destabilization of these forests could result in considerable carbon loss. Among the external factors affecting vegetation, elevated CO2 (eCO2) levels have long been anticipated to have positive impacts on vegetation, including the direct enhancement of both photosynth...

Photosynthetically active radiation (PAR) is typically defined as light with a wavelength within 400–700 nm. However, ultra‐violet (UV) radiation within 280–400 nm and far‐red (FR) radiation within 700–750 nm can also excite photosystems, though not as efficiently as PAR. Vegetation and land surface models (LSMs) typically do not explicitly account...

In the framework of the RECCAP2 initiative, we present the greenhouse gas (GHG) and carbon (C) budget of Europe. For the decade of the 2010s, we present a bottom-up (BU) estimate of GHG net-emissions of 3.9 Pg CO2-eq. yr-1 (global warming potential on 100 year horizon), and are largely dominated by fossil fuel emissions. In this decade, terrestrial...

Plain Language Summary Microwave satellite measurements offer valuable insights into Vegetation Optical Depth (VOD), which reflects the amount of water present in plants. However, most VOD products currently available only offer observations at two times of the day, which fail to capture the variations of VOD over the course of the day. In this stu...

The Amazon rainforest plays a crucial role in global carbon storage, but a minor destabilization of these forests could result in considerable carbon loss. Among the external factors affecting vegetation, elevated CO2 (eCO2) levels have long been anticipated to have positive impacts on vegetation, including direct photosynthesis / productivity enha...

Vegetation optical depth (VOD) is seasonally sensitive to plant water content and aboveground biomass. This index has a strong penetrability within the vegetation canopy and is less impacted by atmosphere aerosol contamination effects, clouds and sun illumination than optical vegetation indices. VOD is thus increasingly applied in ecological applic...

Extreme drought events in Amazon forests are expected to become more frequent and more intense with climate change, threatening ecosystem function and carbon balance. Yet large uncertainties exist on the resilience of this ecosystem to drought. A better quantification of tree hydraulics and mortality processes is needed to anticipate future drought...

During the last two decades, inventory data show that droughts have reduced biomass carbon sink of the Amazon forest by causing mortality to exceed growth. However, process‐based models have struggled to include drought‐induced responses of growth and mortality, and have not been evaluated against plot data. A process‐based model, ORCHIDEE‐CAN‐NHA,...

The 2015/16 El Niño brought severe drought and record-breaking temperatures in the tropics. Here, using satellite-based L-band microwave vegetation optical depth, we mapped changes of above-ground biomass (AGB) during the drought and in subsequent years up to 2019. Over more than 60% of drought-affected intact forests, AGB reduced during the drough...

Extreme drought events in Amazon forests are expected to become more frequent and more intense with climate change, threatening ecosystem function and carbon balance. Yet large uncertainties exist on the resilience of this ecosystem to drought. A better quantification of tree hydraulics and mortality processes is needed to anticipate future drought...

Soil heterotrophic respiration (SHR) is important for carbon‐climate feedbacks because of its sensitivity to soil carbon, climatic conditions and nutrient availability. However, available global SHR estimates have either a coarse spatial resolution or rely on simple upscaling formulations. To better quantify the global distribution of SHR and its r...

Drought can weaken forest activity and even lead to forest mortality, and the response of different forest types to drought can be diverse. Deciduous broadleaf forest (DBF) and deciduous needleleaf forest (DNF) are two of the majority forest types in northern China. In this region, a severe drought event happened in 2002. However, due to the lack o...

Resolving regional carbon budgets is critical for informing land-based mitigation policy. For nine regions covering nearly the whole globe, we collected inventory estimates of carbon-stock changes complemented by satellite estimates of biomass changes where inventory data are missing. The net land–atmospheric carbon exchange (NEE) was calculated by...

Most studies of the northern hemisphere carbon cycle based on atmospheric CO2 concentration have focused on spring and autumn, but the climate change impact on summer carbon cycle remains unclear. Here we used atmospheric CO2 record from Point Barrow (Alaska) to show that summer CO2 drawdown between July and August, a proxy of summer carbon uptake,...

This supplementary materials provide additional information mainly regarding the spatial patterns of biomass and soil carbon turnover times derived with models, spatial sensitivity of modeled biomass and soil carbon turnover time to temperature (T) and precipitation (P), and uncertainty analysis, including comparing carbon turnover time results usi...

Chinese forests, characterized by relatively young stand age, represent a significant biomass carbon (C) sink over the past several decades. Nevertheless, it is unclear how forest biomass C sequestration capacity in China will evolve as forest age, climate and atmospheric CO2 concentration change continuously. Here, we present a semi-empirical mode...

Earth System Models (ESMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) were diagnosed large discrepancies in their land carbon turnover times, which partly explains the differences in the future projections of terrestrial carbon storage from the models. Carvalhais et al. (2014) focused on evaluation of model-based ecosystem carbo...

Accurate assessment of the strength of China's terrestrial ecosystem carbon sink is key to understanding its regional carbon budget. However, large uncertainties in current carbon sink estimations still exist, which hinder the prediction of future climate change trajectories. In this study, we generated a high-resolution (1 km × 1 km) dataset of Ch...

Eddy covariance Evapotranspiration Model tree ensemble (MTE) Spatio-temporal change Land surface model A B S T R A C T Evapotranspiration (ET) is one of the most important fluxes in terrestrial ecosystems that regulate atmosphere -hydrosphere-biosphere interactions. Several studies have suggested that global ET has significantly increased in the pa...

Pronounced warming occurring on the Tibetan Plateau is expected to stimulate alpine grassland growth but could also increase atmospheric aridity that limits photosynthesis. But there lacks a systematic assessment of the impact of atmospheric aridity on alpine grassland productivity. Here we combine satellite observations, flux-tower-based productiv...

No consensus has yet been reached on the major factors driving the observed increase in the seasonal amplitude of atmospheric CO2 in the northern latitudes. In this study, we used atmospheric CO2 records from 26 northern hemisphere stations with a temporal coverage longer than 15 years, and an atmospheric transport model prescribed with net biome p...

Significance Agricultural production is vulnerable to climate change. Understanding climate change, especially the temperature impacts, is critical if policymakers, agriculturalists, and crop breeders are to ensure global food security. Our study, by compiling extensive published results from four analytical methods, shows that independent methods...

The uncertainties of China's GPP estimates by global data-oriented products and ecosystem models justify a development of high-resolution data-oriented GPP dataset over China. We applied a machine learning algorithm developing a new GPP dataset for China with 0.1° spatial resolution and monthly temporal frequency based on eddy flux measurements fro...

Ongoing spring warming allows the growing season to begin earlier, enhancing carbon uptake in northern ecosystems. Here we use 34 years of atmospheric CO 2 concentration measurements at Barrow, Alaska (BRW, 71° N) to show that the interannual relationship between spring temperature and carbon uptake has recently shifted. We use two indicators: the...

There is an increasing demand to integrate land surface temperature (LST) into climate research due to its global coverage, which requires a comprehensive knowledge of its distinctive characteristics compared to near-surface air temperature (Tair). Using satellite observations and in situ station-based data sets, we conducted a global-scale assessm...

Forest stand age is a meaningful metric, which reflects the past disturbance legacy, provides guidelines for forest management practices, and is an important factor in qualifying forest carbon cycles and carbon sequestration potential. Reliable large-scale forest stand age information with high spatial resolutions, however, is difficult to obtain....

Widespread afforestation programs sequester carbon from the atmosphere and mitigate the rising of atmospheric carbon dioxide (CO2). Meanwhile, afforestation carbon sequestration may cost soil water. However, changes in soil moisture content (SMC) after large-scale afforestation or reforestation have rarely been quantified. In this study, we measure...

Tree height differences between plots that top 1m soil moisture content in control plots (SMCc,0-1m) are above and below the threshold for five tree species. Error bars show confidence interval of tree height difference. The asterisks (*) denote that tree height differences between plots that SMCc,0-1m are above and below the threshold are signific...

Relationships between change of top 1m soil moisture content (ΔSMC0-1m) and top 1m soil moisture content in control plots (SMCc,0-1m) for five tree species. (a) Pinus koraiensis, (b) Larix gmelinii, (c) Pinus sylvestris var. mongolica, (d) Pinus tabuliformis, (e) Populus spp.. SMCc,0-1m was divided into 25 bins. The numbers in the top right are the...

Sample sites information in our experiment. The longitude, latitude and name of forest farms are provided as below. (DOCX)

Sample data in our experiment. The mean and standard deviation (std) of change in top 1-m soil moisture content (ΔSMC0-1m) in each site. (DOCX)

Terrestrial carbon fluxes are sensitive to climate change, but the interannual climate sensitivity of the land carbon cycle can also change with time. We analyzed the changes in responses of net biome production (NBP), net primary production (NPP), and heterotrophic respiration (Rh) to interannual climate variations over the 21st century in the Ear...

Ecosystem water-use efficiency (EWUE) is an indicator of carbon-water interactions and is defined as the ratio of carbon assimilation (GPP) to evapotranspiration (ET). Previous research suggests an increasing long-term trend in annual EWUE over many regions and is largely attributed to the physiological effects of rising CO2. The seasonal trends in...