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. 2023 Feb:151:102869.
doi: 10.1016/j.apgeog.2022.102869. Epub 2023 Jan 2.

Improved air quality leads to enhanced vegetation growth during the COVID-19 lockdown in India

Rahul Kashyap  1 , J Kuttippurath  1 , V K Patel  1
Affiliations

Improved air quality leads to enhanced vegetation growth during the COVID-19 lockdown in India

Rahul Kashyap et al. Appl Geogr. 2023 Feb.

Abstract

The direct effect of pandemic induced lockdown (LD) on environment is widely explored, but its secondary impacts remain largely unexplored. Therefore, we assess the response of surface greenness and photosynthetic activity to the LD-induced improvement of air quality in India. Our analysis reveals a significant improvement in air quality marked by reduced levels of aerosols (AOD, -19.27%) and Particulate Matter (PM 2.5, -23%) during LD (2020)from pre-LD (March-September months for the period 2017-2019). The vegetation exhibits a positive response, reflected by the increase in surface greenness [Enhanced Vegetation Index (EVI, +10.4%)] and photosynthetic activity [Solar Induced Fluorescence (SiF, +11%)], during LD from pre-LD that coincides with two major agricultural seasons of India; Zaid (March-May) and Kharif (June-September). In addition, the croplands show a higher response [two-fold in EVI (14.45%) and four-fold in SiF (17.7%)] than that of forests. The prolonged growing period (phenology) and high rate of photosynthesis (intensification) led to the enhanced greening during LD owing to the reduced atmospheric pollution. This study, therefore, provides new insights into the response of vegetation to the improved air quality, which would give ideas to counter the challenges of food security in the context of climate pollution, and combat global warming by more greening.

Keywords: Air quality; COVID-Lockdown; Cropland; Enhanced greening; Intensification; Phenology.

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Conflict of interest statement

The authors declare no conflict of interest, financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Image 1
Graphical abstract
Fig. 1
Fig. 1
Enhanced Vegetation Index (EVI) and Solar Induced Fluorescence (SiF) (kW m−2 μm−1 sr−1) for vegetated land (upper panel), croplands (middle panel) and forests (lower panel) averaged over March–September in 2000–2021. Here, LD stands for the data averaged over the period March–September 2020 and PostLD stands for the data averaged over the same months, but for 2021.
Fig. 2
Fig. 2
Distribution of Enhanced Vegetation Index (EVI) (upper panel) and Solar Induced Fluorescence (SiF) (kW m−2 μm−1 sr−1) (lower panel) in India averaged over March–September during the three focal periods: PreLD (2017–2019), LD (2020) and PostLD (2021).
Fig. 3
Fig. 3
Change (%) in Enhanced Vegetation Index (EVI) (upper panel) and Solar Induced Fluorescence (SiF) (lower panel) in India for the three time periods: LD (2020) - Pre LD (2017–2019), LD (2020) - PostLD (2021) and PostLD (2021) - PreLD (2017–2019).
Fig. 4
Fig. 4
Percentage (%) change in Aerosol Optical Depth (AOD, top panel), Particulate Matter (PM 2.5, middle panel) and Sulphur Dioxide (SO2, bottom panel) over India for the three time periods: LD (2020) - PreLD (2017–2019), PostLD (2021) - PreLD (2017–2019) and LD (2020) - PostLD (2021).
Fig. 5
Fig. 5
Percentage (%) change in temperature (T, top panel), precipitation (P, middle panel) and Downward Surface Radiation Flux (DSRF, bottom panel) in India for the three time periods: LD (2020) - PreLD (2017–2019), PostLD (2021) - PreLD (2017–2019) and LD (2020) - PostLD (2021).
Fig. 6
Fig. 6
Change (%) in Enhanced Vegetation Index (EVI), Solar Induced Fluorescence (SiF), Aerosol Optical Depth (AOD), Particulate Matter (PM 2.5) for the three time periods: LD (2020) - PreLD (2017–2019), LD (2020) - PostLD (2021) and PostLD (2021) - PreLD (2017–2019) in the Indian monsoon homogeneous regions (bottom right): Hilly Region (HR), North East India (NEI), Indo-Gangetic Plains, South or Peninsular India (SI), Central India (CI) and North West (NW). The climate zones based on Köppen classification are also shown (top right).
Fig. 7
Fig. 7
Top panel. Spatial extent of the vegetated land in terms of croplands and forests in India, change in vegetation cover represented by Enhanced Vegetation Index (EVI), and Photosynthetic activity and productivity represented by Solar Induced Fluorescence (SiF) during LD (2020) from that in pre-LD (2017–2019). Bottom panel. Percentage (%) change in EVI, SiF, Aerosol Optical Depth (AOD) and Particulate Matter (PM 2.5) during LD (2020) from that in the pre-LD (2017–2019) for the net vegetated land (over all represents both croplands and forests), croplands and forests.
Fig. 8
Fig. 8
Change in photosynthetic activity and productivity represented in terms of Solar Induced Fluorescence (SiF) from March to September during the three focal periods: PreLD (2017–2019), LD (2020) and PostLD (2021) to show (i) change in phonology: (a) early onset of vegetative season, (b) late withdrawal of vegetative season; (ii) Intensification (enhancement in Photosynthetic activity and productivity) during: (c) phase of decline in SiF, and (d) phase of increase in SiF. The regions marked in red show the particular crop type, based on data from Ministry of Agriculture, Government of India (GOI). The red line (upper panel) represents the mean SiF value for the period 2017–2019 (baseline).
See this image and copyright information in PMC

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