Zaichun Zhu

Zaichun Zhu
Peking University | PKU · School of Urban Planning & Design

PhD

About

74
Publications
59,997
Reads
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7,572
Citations
Citations since 2016
54 Research Items
7092 Citations
201620172018201920202021202205001,0001,500
201620172018201920202021202205001,0001,500
201620172018201920202021202205001,0001,500
201620172018201920202021202205001,0001,500
Additional affiliations
July 2013 - June 2014
Chinese Academy of Sciences
Position
  • Research Assistant
September 2011 - March 2013
Boston University
Position
  • Researcher
January 2007 - January 2013
Beijing Normal University
Position
  • PhD Student

Publications

Publications (74)
Article
Full-text available
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...
Article
Full-text available
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...
Article
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...
Article
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...
Article
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...
Article
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...
Article
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...
Article
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...
Article
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...
Data
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...
Article
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...
Article
Full-text available
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...
Article
Continuous atmospheric CO 2 monitoring data indicate an increase in the amplitude of seasonal CO 2-cycle exchange (SCA NBP) in northern high latitudes. The major drivers of enhanced SCA NBP remain unclear and intensely debated, with land-use change, CO 2 fertilization and warming being identified as likely contributors. We integrated CO 2-flux data...
Preprint
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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...
Article
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)...
Article
Full-text available
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-...
Article
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...
Article
Full-text available
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...
Data
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...
Article
Full-text available
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...
Article
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...
Article
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...
Article
Full-text available
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...
Article
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...
Article
Full-text available
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...
Article
Full-text available
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...
Data
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...
Data
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...
Data
Sample sites information in our experiment. The longitude, latitude and name of forest farms are provided as below. (DOCX)
Data
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)
Article
Full-text available
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...
Data
Download the data: http://pan.baidu.com/s/1kUXTQp5
Article
Full-text available
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...
Article
Full-text available
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...
Article
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...
Data
Figure S4. Replotted figure SPM 1a from IPCC Summary for Policy Makers (2013).
Data
Figure S5. Effects of the El Chichón and Pinatubo eruptions on radiation, redrawn from Robock (2000).
Data
Figure S1. Autocorrelograms (a) for observed and (b) for simulated time series.
Data
Figure S3. Comparison of multiple STARS on real and artificial time series: shift strength.
Data
Table S2. Supporting source, background and methodology citations.
Data
Table S3. Additional information and notes on the time series presented in Fig. 2.
Data
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.
Data
Figure S2. Comparison of multiple STARS on real and artificial time series: shift years.
Data
Table S1. Excel Database that includes all the annual values of the 72 analysed time series.
Data
Table S4. Coordinates for six regions of tropical hurricanes/storms in Fig. 6.
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
We examined natural and anthropogenic controls on terrestrial evapotranspiration (ET) changes from 1982 to 2010 using multiple estimates from remote sensing-based datasets and process-oriented land surface models. A significant increasing trend of ET in each hemisphere was consistently revealed by observationally-constrained data and multi-model en...
Article
Full-text available
Understanding how the dynamics of vegetation growth respond to climate change at different temporal and spatial scales is critical to projecting future ecosystem dynamics and the adaptation of ecosystems to global change. In this study, we investigated vegetated growth dynamics (annual productivity, seasonality and the minimum amount of vegetated c...
Article
Full-text available
Past changes in gross primary productivity (GPP) were assessed using historical satellite observations based on the Normalized Difference Vegetation Index (NDVI) from the Advanced Very High Resolution Radiometer (AVHRR) onboard the National Oceanic and Atmospheric Administration (NOAA) satellite series and four terrestrial biosphere models to ident...
Article
Full-text available
Leaf Area Index (LAI) represents the total surface area of leaves above a unit area of ground and is a key variable in any vegetation model, as well as in climate models. New high resolution LAI satellite data is now available covering a period of several decades. This provides a unique opportunity to validate LAI estimates from multiple vegetation...