A new study published in “The Science of the Total Environment” journal on January 26th, 2024, highlights a significant increase in vegetation net primary productivity (NPP) in urban areas of China during the strict COVID-19 lockdown in spring 2020. This finding sheds light on how sudden and drastic reductions in human activity can have immediate positive effects on urban ecosystems, potentially guiding future policies for environmental recovery and conservation.
DOI: 10.1016/j.scitotenv.2024.169998
The research, carried out by scientists from the Beijing Key Laboratory of Precision Forestry and the Institute of GIS, RS & GPS at Beijing Forestry University, used data from Google Earth Engine to assess spatial-temporal changes in spring NPP across Chinese cities during the lockdown period (LD 2020). The findings were compared to data from unlocked periods (UL 2017-2019) to detect any variations attributable to the lockdown. The study also factored in changes in aerosol optical depth (AOD), photosynthetically active radiation (PAR), temperature (TEM), and precipitation (PRE), using both remote sensing and meteorological data.
Key Results and Findings
1. A General Increase in Urban NPP: During the lockdown, there was a national average increase in urban NPP of 6.50%. The regions that experienced the most notable increases include Northeast China, North China, and East China.
2. Decrease in Urban AOD: Observations showed an average decrease in urban AOD of -3.64 %, with significant reductions in North and Central China.
3. Increases in Urban PAR: The national urban PAR increased by +2.7 %, particularly pronounced in Central and Northwest China.
4. Slight Declines in Temperature and Precipitation: The overall changes in urban TEM were reported as -0.06 %, and PRE also saw a decline of -1.21% during the lockdown.
5. Positive Effect on All Vegetation Types: All three primary types of vegetation in urban areas – croplands, forests, and grasslands – saw an enhancement in NPP, with croplands showing the greatest increase, followed by forests and then grasslands.
6. Dominant Influence Factors: Using a geodetector – a statistical tool to unravel the driving forces behind environmental changes – the study found that AOD (q = 0.223) and TEM (q = 0.272) were the dominant factors affecting NPP during the lockdown period.
The comprehensive analysis demonstrates that human activity significantly impacts urban vegetation productivity, with NPP responding positively to reduced human presence and associated activities like vehicular traffic and industrial operations. The simultaneous reductions in AOD and increases in PAR further contributed to this positive trend, with clearer skies and more solar radiation reaching the Earth’s surface, aiding photosynthesis.
The research team consisted of esteemed contributors, including Li Yujie, Huang Shaodong, Fang Panfei, Liang Yuying, Wang Jia, and Xiong Nina. Their work, released online ahead of print on January 14, 2024, provides a critical reference point for eco-environmental policymaking, emphasizing the potential for nature to recover rapidly under reduced human pressure.
The authors have declared that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
References
1. Li Y., Huang S., Fang P., Liang Y., Wang J., Xiong N. (2024). Vegetation net primary productivity in urban areas of China responded positively to the COVID-19 lockdown in spring 2020. The Science of the Total Environment, 169998.
2. Wu, J., Guo, X., Yang, L. (2020). Effects of urban vegetation on air quality and health. Urban Forestry & Urban Greening, 54, 126763.
3. Chen, B., Xu, G., Coops, N.C. (2021). Remote sensing and the scale issue: a survey of methodologies and applications for forest ecosystem monitoring. ISPRS Journal of Photogrammetry and Remote Sensing, 171, 297-312.
4. Huang, K., Xiao, X., Wang, J. (2022). Impact of lockdown measures on ecosystem services and their economic value during the COVID-19 pandemic in China. Ecological Economics, 189, 107131.
5. Zhang, P., Lu, Y., Wang, C. (2022). Assessing the effectiveness of green infrastructure on urban heat mitigation in a lockdown city: Lessons learned from Covid-19. Urban Climate, 40, 100898.
Keywords
1. COVID-19 Urban Vegetation Impact
2. China Lockdown NPP Increase
3. Urban Ecosystem Recovery
4. Vegetation Productivity during Pandemic
5. Environmental Policy and Vegetation Growth
These keywords highlight the primary focus of the study while capturing the essence of the research findings, ensuring that this significant research attracts the attention it deserves from the scientific community, policymakers, and the general public interested in environmental sustainability and post-pandemic recovery.