Zaichun Zhu

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Verified

Zaichun verified their affiliation via an institutional email.

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• Doctor of Philosophy
• Professor (Associate) at Peking University

Long-term global data sets of vegetation Leaf Area Index (LAI) and Fraction of Photosynthetically Active Radiation absorbed by vegetation (FPAR) are critical to monitoring global vegetation dynamics and for modeling exchanges of energy, mass and momentum between the land surface and planetary boundary layer. LAI and FPAR are also state variables in...

Global environmental change is rapidly altering the dynamics of terrestrial vegetation, with consequences for the functioning of the Earth system and provision of ecosystem services. Yet how global vegetation is responding to the changing environment is not well established. Here we use three long-term satellite leaf area index (LAI) records and te...

The seasonal dynamics of the vegetation canopy strongly regulate the surface energy balance and terrestrial carbon fluxes, providing feedbacks to climate change. Whether the seasonal timing of maximum canopy structure was optimized to achieve a maximum photosynthetic carbon uptake is still not clear due to the complex interactions between abiotic a...

Leaf area index (LAI) with an explicit biophysical meaning is a critical variable to characterize terrestrial ecosystems. Long-term global datasets of LAI have served as fundamental data support for monitoring vegetation dynamics and exploring its interactions with other Earth components. However, current LAI products face several limitations assoc...

Global products of remote sensing Normalized Difference Vegetation Index (NDVI) are critical to assessing the vegetation dynamic and its impacts and feedbacks on climate change from local to global scales. The previous versions of the Global Inventory Modeling and Mapping Studies (GIMMS) NDVI product derived from the Advanced Very High Resolution R...

Leaf angle distribution (LAD) impacts plant photosynthesis, water use efficiency, and ecosystem primary productivity, which are crucial for understanding surface energy balance and climate change responses. Traditional LAD measurement methods are time‐consuming and often limited to individual sites, hindering effective data acquisition at the ecosy...

Plain Language Summary In recent decades, China has implemented large‐scale afforestation projects, significantly contributing to global greening. However, the greening trend in China has been underestimated by Dynamic Global Vegetation Models (DGVMs). The underestimation may be from the uncertainties in plant functional types data, but solid evide...

Coastal vegetation serves as a protective buffer against the deleterious impacts of storm surges, influencing the dynamic exchange of energy and matter and mediating the lateral transport of carbon from land to the ocean. Comprehensive understanding of coastal vegetation dynamics is crucial for sustaining the ecological and biogeochemical functions...

Typhoons are undergoing changes in frequency, intensity, and landward movement due to climate change, placing coastal vegetation ecosystems at heightened risk. These ecosystems provide critical ecological, social, and economic functions, making accurate assessment of typhoon impacts essential for effective management and disaster risk reduction. Tr...

Woody plant encroachment (WPE) has been widely studied, yet the spatiotemporal pattern of global WPE and its drivers remain unclear. Here, based on long-term remote sensing observations, we investigated the spatiotemporal dynamics of global WPE from 2001 to 2020 and assessed the contributions of the changes in main environmental factors. We found a...

As a proxy of vegetation photosynthesis, solar-induced chlorophyll fluorescence (SIF) contains rich photosynthetic information that can reveal the physiological state of vegetation and its response to the environment. Current publicly available SIF products vary in accuracy, spatiotemporal resolution, and coverage due to the different inversion alg...

The fraction of absorbed photosynthetically active radiation (FPAR) is an essential biophysical parameter that characterizes the structure and function of terrestrial ecosystems. Despite the extensive utilization of several satellite-derived FPAR products, notable temporal inconsistencies within each product have been underscored. Here, the new gen...

During extensive periods without rain, known as dry-downs, decreasing soil moisture (SM) induces plant water stress at the point when it limits evapotranspiration, defining a critical SM threshold (θcrit). Better quantification of θcrit is needed for improving future projections of climate and water resources, food production, and ecosystem vulnera...

Drylands are a pivotal component of Earth’s biosphere and provide essential ecosystem services to mankind. Over the past several decades, with rapid population growth, global drylands have been experiencing quick socioeconomic transitioning. Such socioeconomic changes, together with fast climate change, have dramatically altered dryland ecosystem f...

Climate change is causing widespread land surface greening in spring1–4, but the impacts of anthropogenic air pollution on these changes remain poorly understood. Using global ground and satellite observations of fine particulate matter ≤ 2.5 μm (PM2.5) from 2000 to 2020, here we show that PM2.5 concentration offsets global spring greening as indic...

Land cover products provide critical information for monitoring and analyzing land surface changes. However, notable disagreement and incompatible classification systems among existing land cover products bring challenges in using them. Here, we developed a hierarchical International Geosphere-Biosphere Programme (IGBP) classification system and in...

Leaf area index (LAI) and fraction of photosynthetically active radiation (FPAR) are critical biophysical parameters for the characterization of terrestrial ecosystems. Long-term global LAI/FPAR products, such as the moderate resolution imaging spectroradiometer (MODIS) and the Visible Infrared Imaging Radiometer Suite (VIIRS), provide the fundamen...

Gross primary productivity (GPP) is jointly controlled by the structural and physiological properties of the vegetation canopy and the changing environment. Recent studies showed notable changes in global GPP during recent decades and attributed it to dramatic environmental changes. Environmental changes can affect GPP by altering not only the biog...

Global vegetation has experienced notable changes in greenness and productivity since the early 1980s. However, the changes in the relationship between productivity and greenness, i.e., the coupling, and its underlying mechanisms, are poorly understood. The Loess Plateau (LP) is one of China’s most significant areas for vegetation greening. Yet, it...

Leaf area index (LAI) and fraction of photosynthetically active radiation (FPAR) are critical biophysical parameters for the characterization of terrestrial ecosystems. Long-term global LAI/FPAR products, such as MODIS&VIIRS, provide the fundamental dataset for accessing vegetation dynamics and studying climate change. However, existing global LAI/...

The long-term global Leaf Area Index (LAI) products are critical supports for characterizing the changes in land surface and its interactions with other components of the Earth system under the dramatic global change. However, intercomparisons between current available long-term global LAI products present significant spatiotemporal inconsistencies...

Crossing certain aridity thresholds in global drylands can lead to abrupt decays of ecosystem attributes such as plant productivity, potentially causing land degradation and desertification. It is largely unknown, however, whether these thresholds can be altered by other key global change drivers known to affect the water-use efficiency and product...

The direct biophysical effects of fine-scale tree cover changes on temperature are not well understood. Here, we show how land surface temperature responds to subgrid gross tree cover changes. We find that in many forests, the biophysical cooling induced by enhanced evapotranspiration due to tree cover gain is greater in magnitude than the warming...

Leaf Area Index (LAI) with an explicit biophysical meaning is a critical variable to characterize terrestrial ecosystems. Long-term global datasets of LAI have served as fundamental data support for monitoring vegetation dynamics and exploring its interactions with other Earth components. However, current LAI products face several limitations assoc...

Global products of remote sensing Normalized Difference Vegetation Index (NDVI) are critical to assessing the vegetation dynamic and its impacts and feedbacks on climate change from local to global scales. The previous versions of the Global Inventory Modelling and Mapping Studies (GIMMS) NDVI product derived from the Advanced Very High Resolution...

Urban vegetation, a harbinger of future global vegetation change, is controlled by complex urban environments. The urban-rural gradient in vegetation greenness trends and their responses to biogeochemical drivers (e.g. elevated atmospheric CO2 concentration and climate warming) and land-cover changes, however, remain unclear. Here we used satellite...

As the largest source of uncertainty in carbon cycle studies, accurate quantification of gross primary productivity (GPP) is critical for the global carbon budget in the context of global climate change. Numerous vegetation indices (VIs) based on satellite data have participated in the construction of GPP models. However, the relative performance o...

Ecological connectivity is the foundation of maintaining urban biodiversity and ecosystem health. Identifying and managing ecological (connectivity) networks can help maintain the stability of urban ecosystems. However, few studies have explored the cluster effect in the ecological network caused by the imbalance in connectivity strength between ha...

An unsupervised change-detection problem is formulated as a binary classification problem corresponding to the change and no change areas. This paper proposes a novel unsupervised object-oriented change detection method based on neighborhood correlation images (NCIs) and k-means clustering for high-resolution remote sensing images. We tested our pr...

Tropical Dry Forests (TDFs) in the Americas are significantly affected by drought related to El Niño Southern Oscillation (ENSO). The analysis builds upon two drought indices: the MODIS-derived Vegetation Condition Index (VCI) and Temperature Condition Index (TCI) and the Sea Surface Temperature (SST) anomaly in the Niño 3.4 region. Temporal correl...

Wang et al . (Research Articles, 11 December 2020, p. 1295) reported a large decrease in CO 2 fertilization effect (CFE) across the globe during the period 1982–2015 and suggested that ecosystem models underestimate the rate of CFE decline. We find that their claims are artifacts of incorrect processing of satellite data and problematic methods for...

Vegetation in urban settings is heavily altered by anthropogenic impacts. However, the impacts of urbanization on vegetation are not well understood. Here, we quantified the impacts of urbanization on vegetation in 48 Chinese coastal cities and explored their dynamic characteristics from 1990 to 2015. The indirect impacts of urbanization on vegetat...

If you use the dataset, please cite the reference: Song, X., Li, F., Harrison, S. P., Luo, T., Arneth, A., Forrest, M., Hantson, S., Lasslop, G., Mangeon, S., and Ni, J.: Vegetation biomass change in China in the 20th century: An assessment based on a combination of multi-model simulations and field observations, Environ. Res. Lett.,15, 094026, ht...

Changes in global vegetation growth and its drivers during recent decades have been well studied with satellite data, ecosystem models and field experiments. However, a systematic understanding of how global vegetation will respond to projected changes in climate and atmospheric composition is still lacking. Here, we analyze changes in projected gl...

Vegetation biomass is a key and active component of the carbon cycle. Though China’s vegetation biomass in recent decades has been widely investigated, only two studies have quantitatively assessed its century-scale changes so far and reported totally opposite trends. This study provided the first multi-model estimates of China’s vegetation biomass...

Continuous atmospheric CO2 monitoring data indicate an increase in the amplitude of seasonal CO2-cycle exchange (SCANBP) in northern high latitudes. The major drivers of enhanced SCANBP remain unclear and intensely debated, with land-use change, CO2 fertilization and warming being identified as likely contributors. We integrated CO2-flux data from...

Continuous atmospheric CO2 monitoring data indicate an increase in seasonal-cycle amplitude (SCA) of CO2 exchange in northern high latitudes. The major drivers of enhanced SCA remain unclear and intensely debated with land-use change, CO2 fertilization and warming identified as likely contributors. We integrated CO2-flux data from two atmospheric i...

Satellite data show increasing leaf area of vegetation due to direct factors (human land-use management) and indirect factors (such as climate change, CO2 fertilization, nitrogen deposition and recovery from natural disturbances). Among these, climate change and CO2 fertilization effects seem to be the dominant drivers. However, recent satellite da...

The terrestrial carbon sink accelerated during 1998–2012, concurrently with the slow warming period, but the mechanisms behind this acceleration are unclear. Here we analyse recent changes in the net land carbon sink (NLS) and its driving factors, using atmospheric inversions and terrestrial carbon models. We show that the linear trend of NLS durin...

Dietary change is a win-win opportunity to address the nexus of health and the environment. To prevent city dwellers from developing non-communicable diseases, in 2013, China updated the 2000 version of nutrition-based dietary reference intake (DRI) guidelines. However, whether the DRI guidelines have a positive effect on the environment is not wel...

While remotely-sensed data reveal enhanced vegetation growth under a warming climate, how such vegetation dynamics could alter regional hydrology is not fully understood. In this study, we investigated how changes in leaf area index (LAI) and climatic variability alter long-term trends and seasonal variability of evapotranspiration (ET), runoff (R)...

Recent studies attributed the accelerating land carbon sink (SLAND) during the 2000s to respiration decrease induced by the warming hiatus. We used two long-term atmospheric inversions, three temperature datasets and eight ecosystem models to test this attribution. Our results show that the changes in seasonal SLAND trend between the warming (1982-...

To assess global carbon cycle variability, we decompose the net land carbon sink into the sum of gross primary productivity (GPP), terrestrial ecosystem respiration (TER) and fire emissions (FR), and apply a Bayesian framework to constrain these fluxes between 1980 and 2014. The constrained GPP and TER fluxes show an increasing trend of only half o...

Warming is projected to increase the productivity of northern ecosystems. However, knowledge on whether the northward displacement of vegetation productivity isolines matches that of temperature isolines is still limited. Here we compared changes in the spatial patterns of vegetation productivity and temperature using the velocity of change concept...

Zhu Z, Bi J, Pan Y, Ganguly S, Anav A, Xu L, Samanta A, Piao S, Nemani RR, Myneni RB. Global Data Sets of Vegetation Leaf Area Index (LAI)3g and Fraction of Photosynthetically Active Radiation (FPAR)3g Derived from Global Inventory Modeling and Mapping Studies (GIMMS) Normalized Difference Vegetation Index (NDVI3g) for the Period 1981 to 2011. Remo...

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...

Understanding the long-term performance of global satellite leaf area index (LAI) products is important for global change research. However, few effort has been devoted to evaluating the long-term time series consistencies of LAI products. This study compared four long-term LAI products (GLASS, GLOBMAP, LAI3g, and TCDR) in terms of trends, interann...

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...

Significant increases in remotely sensed vegetation indices in the northern latitudes since the 1980s have been detected and attributed at annual and growing season scales. However, we presently lack a systematic understanding of how vegetation responds to asymmetric seasonal environmental changes. In this study, we first investigated trends in the...

The year 2015 was, at the time, the warmest since 1880, and many regions in the Northern Hemisphere (NH) registered record breaking annual temperatures. Simultaneously, a remarkable and widespread growing season greening was observed over most of the NH in the record from the Moderate Resolution Imaging Spectroradiometer (MODIS) normalized differen...

Large-scale atmospheric circulation patterns (i.e. teleconnections) influence global climate variability patterns and can be studied to provide a simple framework for relating the complex response of ecosystems to climate. This study analyzes the effects of fifteen major teleconnections on terrestrial ecosystem carbon fluxes during 1951-2012 using...

Variations in leaf area index (LAI) are critical to research on forest ecosystem structure and function, especially carbon and water cycle, and their responses to climate change. Using the ensemble empirical mode decomposition (EEMD) method and global inventory modeling and mapping studies (GIMMS) LAI3g dataset from 1982 to 2010, we analyzed the no...

Satellite-observed Earth's greening has been reproduced by the latest generation of Earth System Models (ESMs) participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5). Land evapotranspiration (ET) is expected to rise with increasing leaf area index (LAI, Earth's greening). The responses of ET play a key role in the land–climate i...

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)

Significant land greening in the northern extratropical latitudes (NEL) has been documented through satellite observations during the past three decades. This enhanced vegetation growth has broad implications for surface energy, water and carbon budgets, and ecosystem services across multiple scales. Discernible human impacts on the Earth's climate...

Download the data: http://pan.baidu.com/s/1kUXTQp5

The timing of the end of the vegetation growing season (EOS) plays a key role in terrestrial ecosystem carbon and nutrient cycles. Autumn phenology is, however, still poorly understood and previous studies generally focused on few species or were very limited in scale. In this study, we applied four methods to extract EOS dates from NDVI records be...

The temporal variance of soil moisture, vegetation and evapotranspiration over land has been recognized to be strongly connected to the temporal variance of precipitation. However, the feedbacks and couplings between these variables are still not well understood and quantified. Furthermore, soil moisture and vegetation processes are associated with...

Terrestrial gross primary production (GPP) is a major flux affecting land–atmosphere CO2 exchange and is important for regulating atmospheric CO2 concentrations, thereby affecting climate change. Dynamic global vegetation models (DGVMs) are important tools for simulation of vegetation productivity and can be coupled with other components of Earth s...

Despite evidence from a number of Earth systems that abrupt temporal changes known as regime shifts are important, their nature, scale and mechanisms remain poorly documented and understood. Applying principal component analysis, change-point analysis and a sequential t-test analysis of regime shifts to 72 time series, we confirm that the 1980s reg...

Figure S4. Replotted figure SPM 1a from IPCC Summary for Policy Makers (2013).

Figure S5. Effects of the El Chichón and Pinatubo eruptions on radiation, redrawn from Robock (2000).

Figure S1. Autocorrelograms (a) for observed and (b) for simulated time series.

Figure S3. Comparison of multiple STARS on real and artificial time series: shift strength.

Table S2. Supporting source, background and methodology citations.

Table S3. Additional information and notes on the time series presented in Fig. 2.

Table S5. Shift year of the time series from Fig. 2 included in the regions of Fig. 6. A compendium of all the supplementary figures and Tables 2‐5 with their legends plus additional references for Table S2.

Figure S2. Comparison of multiple STARS on real and artificial time series: shift years.

Table S1. Excel Database that includes all the annual values of the 72 analysed time series.

Table S4. Coordinates for six regions of tropical hurricanes/storms in Fig. 6.

Despite evidence from a number of Earth systems that abrupt temporal changes known as regime shifts are important, their nature, scale and mechanisms remain poorly documented and understood. Applying principal component analysis, change-point analysis and a sequential t-test analysis of regime shifts to 72 time series, we confirm that the 1980s reg...

Cholera is one of a number of infectious diseases that appears to be influenced by climate, geography and other natural environments. This study analysed the environmental factors of the spatial distribution of cholera in China. It shows that temperature, precipitation, elevation, and distance to the coastline have significant impact on the distrib...

The variance of soil moisture, vegetation and evapotranspiration over land has been recognized to be strongly connected to the variance of precipitation. However, the feedbacks and couplings between these variables are still not well understood and quantified. Furthermore, soil moisture and vegetation processes are associated to a memory and theref...