Xueyan Li

Dr. Xueyan Li


Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 September 2022 in Remote Sensing
Verified
Journal Article
Open access
PDF file
JWJianping Wu
Jianping Wu
Zhongbing ChangZhongbing Chang
Zhongbing Chang
YSYongxian Su
Yongxian Su
CZChaoqun Zhang
Chaoqun Zhang
XWXiong Wu
Xiong Wu
XLXueyan Li
Xueyan Li
Multiple methods have been developed to identify the transition threshold from the reconstructed satellite-derived normalized difference vegetation indices (NDVI) time series and to determine the inflection point corresponding to a certain phenology phase (e.g., the spring green-up date (GUD)). We address an issue that large uncertainties might occur in the inflection point identification of spring GUD using the traditional satellite-based methods since different vegetation types exhibit asynchronous phenological phases over a heterogeneous ecoregion. We tentatively developed a Maximum-derivative-based (MDB) method and provided inter-comparisons with two traditional methods to detect the turning points by the reconstructed time-series data of NDVI for identifying the GUD against long-term observations from the sites covered by a mixture of deciduous forest and herbages in the Pan European Phenology network. Results showed that higher annual mean temperature would advance the spring GUD, but the sensitive magnitudes differed depending on the vegetation type. Therefore, the asynchronization of phenological phases among different vegetation types would be more pronounced in the context of global warming. We found that the MDB method outperforms two other traditional methods (the 0.5-threshold-based method and the maximum-ratio-based method) in predicting the GUD of the subsequent-green-up vegetation type when compared with ground observation, especially at sites with observed GUD of herbages earlier than deciduous forest, while the Maximum-ratio-based method showed better performance for identifying GUDs of the foremost-green-up vegetation type. Although the new method improved in our study is not universally applicable on a global scale, our results, however, highlight the limitation of current inflection point identify algorithms in predicting the GUD derived from satellite-based vegetation indices datasets in an ecoregion with heterogeneous vegetation types and asynchronous phenological phases, which makes it helpful for us to better predict plant phenology on an ecoregion-scale under future ongoing climate warming.

26 September 2022 in Sustainability
Verified
Journal Article
Open access
PDF file
MYMengqi Yang
Mengqi Yang
HZHong Zhu
Hong Zhu
XLXueyan Li
Xueyan Li
WGWeixia Gong
Weixia Gong
XPXiaomei Pang
Xiaomei Pang
DLDanna Lv
Danna Lv
During the past 40 years of reform and opening-up, China has witnessed great progress in people’s health status. Both the occurrence of diseases and people’s understanding of health have undergone profound changes. Scholars are focusing on changing socioeconomic factors to maintain health lifestyles, and creating healthy “human–land” relations to prevent diseases. From the perspective of health geography, this research conducted field work in Bama, a longevous area in the Guangxi province in China, and applied the theoretical framework of health lifestyles theory to clarify the construction process of health lifestyles for older people in Bama. The roles and characteristics of different social relations in creating health lifestyles are revealed. The findings of this research can provide a new paradigm for China’s health practice research from two aspects: (1) the production of health lifestyles is a knowledge construction process, taking into account the influence of social circumstances, politics, economy, culture, policy, and values; and (2) social attributes affect health lifestyles by reconstructing and improving social relations.

11 October 2023 in Climate
Verified
Journal Article
Open access
PDF file
ZXZili Xiong
Zili Xiong
Wei ShangguanWei Shangguan
Wei Shangguan
Vahid NouraniVahid Nourani
Vahid Nourani
QLQingliang Li
Qingliang Li
XLXingjie Lu
Xingjie Lu
XLXueyan Li
Xueyan Li
Land carbon fluxes play a critical role in ecosystems, and acquiring a comprehensive global database of carbon fluxes is essential for understanding the Earth’s carbon cycle. The primary methods of obtaining the spatial distribution of land carbon fluxes include utilizing machine learning models based on in situ measurements, estimating through satellite remote sensing, and simulating ecosystem models. Recently, an innovative machine learning product known as the Global Carbon Flux Dataset (GCFD) has been released. In this study, we assessed the reliability of the GCFD by comparing it with existing data products, including two machine learning products (FLUXCOM and NIES (National Institute for Environmental Studies)), two ecosystem model products (TRENDY and EC-LUE (eddy covariance–light use efficiency model)), and one remote sensing product (Global Land Surface Satellite), on both site and global scales. Our findings indicate that, in terms of average absolute difference, the spatial distribution of the GCFD is most similar to the NIES product, albeit with slightly larger discrepancies compared to the other two types of products. When using site observations as the benchmark, gross primary production (GPP), respiration of ecosystem (RECO), and net ecosystem exchange of machine learning products exhibit higher R2 (ranging from 0.57 to 0.85, 0.53–0.79, and 0.31–0.70, respectively) compared to model products and remote sensing products. Furthermore, we analyzed the spatial and temporal distribution characteristics of carbon fluxes in various regions. The results demonstrate an upward trend in both GPP and RECO over the past two decades, while NEE exhibits an opposite trend. This trend is particularly pronounced in tropical regions, where higher GPP is observed in tropical, subtropical, and oceanic climate zones. Additionally, two remote sensing variables that influence changes in carbon fluxes, i.e., fraction absorbed photosynthetically active radiation and leaf area index, exhibit relatively consistent spatial and temporal characteristics. Overall, our study can provide valuable insights into different types of carbon flux products and contribute to understanding the general features of global carbon fluxes.

20 January 2025
Verified
Conference Paper
Open access
XCXiuzhi Chen
Xiuzhi Chen
YSYongxian Su
Yongxian Su
XLXueyan Li
Xueyan Li
Restoring tropical forest can provide a large additional carbon sink, yet knowledge of the optimal locations for reforestation programs remains uncertain. By evaluating multiple pantropical forest biomass carbon and height datasets, we find that tropical plantations and regrowth forests (TPFs) situated at elevations ≥ 300 m accumulate 1.5-fold more carbon per year in biomass than their lowland counterparts (elevations < 300 m) prior to reaching maturity. Notably, the biomass carbon accumulation rates increase significantly (P