Skip to main content
Log in

Tracking the seasonal dynamics of Himalayan birch using a time-lapse camera

  • Original research paper
  • Published:
Folia Geobotanica Aims and scope Submit manuscript

Abstract

The use of time-lapse camera setups for characterizing phenology is fast emerging because of their advantages in offering continuous unbiased data. We therefore installed a camera setup in the Western Himalaya to monitor temporal patterns of Betula utilis phenology and also to document snow cover patterns. Digital images (N = 653) of two growing seasons (2017 and 2018) captured through the setup were used for the same. Images hold information in the red, green and blue channels (RGB) and relative changes in RGB indicate canopy colouration. We categorized the phenophases into greenup, leaf maturity, senescence and dormancy. The RGB analyses revealed that during both the years, greenup in B. utilis started during early May [128th and 124th day of the year (DOY) in 2017 and 2018, respectively] and continued till mid-June when the canopy attained maturity. On the other hand, senescence started in early September and by mid-October, the trees became leafless (288th and 289th DOY in 2017 and 2018, respectively). A four-day earlier greenup and dormancy delayed by one day were noted in 2018 when compared to 2017. Thus, the length of the growing season was five days longer in 2018. The snow cover ratio revealed that snowmelt occurred eigth days earlier in 2018 than in 2017. Though this is preliminary, seasonal phenological patterns are evident and call for continued monitoring of B. utilis. The installed setup will provide continuous long-term data from the Himalayan region which had been lacking until now. The present setup for phenological monitoring is pioneering in the Indian Himalaya and needs to be replicated.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6

Similar content being viewed by others

Availability of data and material

All data generated or analysed during this study are available with this published article (Electronic Supplementary Material Fig. S1 and Fig. S2).

Code availability

The R code used is available on request from the author(s)

References

  • Ahrends HE, Brügger R, Stöckli R, Schenk J, Michna P, Jeanneret F, Wanner H, Eugster W (2008) Quantitative phenological observations of a mixed beech forest in northern Switzerland with digital photography. Biogeosciences 113:G04004

    Google Scholar 

  • Arslan AN, Tanis CM, Metsämäki S, Aurela M, Böttcher K, Linkosalmi M, Peltoniemi M (2017) Automated webcam monitoring of fractional snow cover in northern boreal conditions. Geoscience 7:55

    Article  Google Scholar 

  • Bater CW, Coops NC, Wulder MA, Hilker T, Nielsen SE, McDermid G, Stenhouse GB (2011) Using digital time-lapse cameras to monitor species-specific understorey and overstorey phenology in support of wildlife habitat assessment. Environm Monit Assessm 180:1–13

    Article  Google Scholar 

  • Beamish AL, Coops NC, Hermosilla T, Chabrillat S, Heim B (2018) Monitoring pigment-driven vegetation changes in a low-Arctic tundra ecosystem using digital cameras. Ecosphere 9:e02123

    Article  Google Scholar 

  • Bisht VK, Kuniyal CP, Bhandari AK, Nautiyal BP, Prasad P (2014) Phenology of plants in relation to ambient environment in a subalpine forest of Uttarakhand, western Himalaya. Physiol Molec Biol Pl 20:399–403

    Article  Google Scholar 

  • Bobrowski M, Gerlitz L, Schickhoff U (2017) Modelling the potential distribution of Betula utilis in the Himalaya. Glob Ecol Conservation 11:69–83

    Article  Google Scholar 

  • Brown TB, Hultine KR, Steltzer H, Denny EG, Denslow MW, Granados J, Henderson S, Moore D, Nagai S, SanClements M, Sánchez-Azofeifa A (2016) Using phenocams to monitor our changing Earth: toward a global phenocam network. Frontiers Ecol Environm 14:84–93

    Article  Google Scholar 

  • Buckley EMB, Allen CR, Forsberg M, Farrell M, Caven AJ (2017) Capturing change: the duality of time-lapse imagery to acquire data and depict ecological dynamics. Ecol Soc 22:30

    Article  Google Scholar 

  • Cong N, Shen M, Piao S (2016) Spatial variations in responses of vegetation autumn phenology to climate change on the Tibetan Plateau. J Pl Ecol 10:744–752

    Google Scholar 

  • Dhar U (2002) Conservation implications of plant endemism in high-altitude Himalaya. Curr Sci 82:141–148

    Google Scholar 

  • Dolezal J, Dvorsky M, Kopecky M, Liancourt P, Hiiesalu I, Macek M, Altman J, Chlumska Z, Rehakova K, Capkova K, Borovec J (2016) Vegetation dynamics at the upper elevational limit of vascular plants in Himalaya. Sci Rep 6:1–13

    Article  Google Scholar 

  • Dong M, Jiang Y, Zheng C, Zhang D (2012) Trends in the thermal growing season throughout the Tibetan Plateau during 1960–2009. Agric Forest Meteorol 166:201–206

    Article  Google Scholar 

  • Filippa G, Cremonese E, Migliavacca M, Galvagno M, Forkel M, Wingate L, Tomelleri E, Di Cella UM, Richardson AD (2016) Phenopix: a R package for image-based vegetation phenology. Agric Forest Meteorol 220:141–150

    Article  Google Scholar 

  • Fitter AH, Fitter RS (2002) Rapid changes in flowering time in British plants. Science 296:1689–1691

    Article  CAS  PubMed  Google Scholar 

  • Gaira KS, Dhar U, Belwal OK (2011) Potential of herbarium records to sequence phenological pattern: a case study of Aconitum heterophyllum in the Himalaya. Biodivers & Conservation 20:2201–2210

    Article  Google Scholar 

  • Gaira KS, Rawal RS, Rawat B, Bhatt ID (2014) Impact of climate change on the flowering of Rhododendron arboreum in central Himalaya, India. Curr Sci 106:1735–1738

    Google Scholar 

  • Gu L, Post WM, Baldocchi DD, Black TA, Suyker AE, Verma SB, Vesala T, Wofsy SC (2009) Characterizing the seasonal dynamics of plant community photosynthesis across a range of vegetation types. In: Noormets A (ed) Phenology of ecosystem processes. Springer: New York, pp 35–58

    Chapter  Google Scholar 

  • Guo L, Dai J, Wang M, Xu J, Luedeling E (2015) Responses of spring phenology in temperate zone trees to climate warming: a case study of apricot flowering in China. Agric Forest Meteorol 201:1–7

    Article  Google Scholar 

  • Hamid M, Khuroo AA, Charles B, Ahmad R, Singh CP, Aravind NA (2019) Impact of climate change on the distribution range and niche dynamics of Himalayan birch, a typical treeline species in Himalayas. Biodivers & Conservation 28:2345–2370

    Article  Google Scholar 

  • Hart R, Salick J, Ranjitkar S, Xu J (2014) Herbarium specimens show contrasting phenological responses to Himalayan climate. Proc Natl Acad Sci USA 111:10615–10619

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Hik DS, Williamson SN (2019) Need for mountain weather stations climbs. Science 366:1083–1083

    Article  PubMed  Google Scholar 

  • Hufkens K, Friedl M, Sonnentag O, Braswell BH, Milliman T, Richardson AD (2012a) Linking near-surface and satellite remote sensing measurements of deciduous broadleaf forest phenology. Remote Sensing Environm 117:307–321

    Article  Google Scholar 

  • Hufkens K, Friedl MA, Keenan TF, Sonnentag O, Bailey A, O'Keefe J, Richardson AD. (2012b) Ecological impacts of a widespread frost event following early spring leaf-out. Global Change Biol 18:2365–2377

    Article  Google Scholar 

  • Huintjes E, Sauter T, Schröter B, Maussion F, Yang W, Kropáček J, Buchroithner M, Scherer D, Kang S, Schneider C (2015) Evaluation of a coupled snow and energy balance model for Zhadang glacier, Tibetan Plateau, using glaciological measurements and time-lapse photography. Arctic Antarc Alpine Res 47:573–590

    Article  Google Scholar 

  • Ide R, Oguma H (2010) Use of digital cameras for phenological observations. Ecol Inform 5:339–347

    Article  Google Scholar 

  • Ide R, Oguma H (2013) A cost-effective monitoring method using digital time-lapse cameras for detecting temporal and spatial variations of snowmelt and vegetation phenology in alpine ecosystems. Ecol Inform 16:25–34

    Article  Google Scholar 

  • IPCC (2007) Contribution of Working Group II to the fourth assessment report of the intergovernmental panel on climate change. Cambridge University Press, Cambridge

  • Jaryan V, Uniyal SK, Gupta RC, Singh RD (2014) Phenological documentation of an invasive species, Sapium sebiferum (L.) Roxb. Environm Monit Assessm 186:4423–4429

    Article  Google Scholar 

  • Julitta T, Cremonese E, Migliavacca M, Colombo R, Galvagno M, Siniscalco C, Rossini M, Fava F, Cogliati S, di Cella UM, Menzel A (2014) Using digital camera images to analyse snowmelt and phenology of a subalpine grassland. Agric Forest Meteorol 198:116–125

    Article  Google Scholar 

  • Keenan TF, Darby B, Felts E, Sonnentag O, Friedl MA, Hufkens K, O'Keefe J, Klosterman S, Munger JW, Toomey M, Richardson AD (2014) Tracking forest phenology and seasonal physiology using digital repeat photography: a critical assessment. Ecol Applic 24:1478–1489

    Article  CAS  Google Scholar 

  • Kirkham JD, Koch I, Saloranta TM, Litt M, Stigter E, Møen K, Thapa A, Melvold K, Immerzeel WW (2019) Near real-time measurement of snow water equivalent in the Nepal Himalayas. Frontiers Earth Sci 7:1-18

    Article  Google Scholar 

  • Klosterman S, Hufkens K, Gray JM, Melaas E, Sonnentag O, Lavine I, Mitchell L, Norman R, Friedl MA, Richardson A (2014) Evaluating remote sensing of deciduous forest phenology at multiple spatial scales using PhenoCam imagery. Biogeosciences 11: 4305-4320

    Article  Google Scholar 

  • Körner C (2003) Alpine plant life: functional plant ecology of high mountain ecosystems. Springer Science & Business Media

  • Körner, C (2012) Alpine treelines: functional ecology of the global high elevation tree limits. Springer Science & Business Media

  • Kumar A, Lal B, Rajkumar S, Chawla A, Kaushal R (2013) Landscape mapping and tree diversity assessment of Pangi valley: a remote tribal area of Himachal Pradesh in western Himalaya, India. Int J Conservation Sci 4:503–508

    Google Scholar 

  • Kushwaha CP, Singh KP (2008) India needs phenological stations network. Curr Sci 95:832–834

    Google Scholar 

  • Liang E, Dawadi B, Pederson N, Eckstein D (2014) Is the growth of birch at the upper timberline in the Himalayas limited by moisture or by temperature? Ecol 95:2453–2465

    Article  Google Scholar 

  • Liu B, Li Y, Eckstein D, Zhu L, Dawadi B, Liang E (2013) Has an extending growing season any effect on the radial growth of Smith fir at the timberline on the southeastern Tibetan Plateau? Trees 27:441–446

    Article  Google Scholar 

  • Liu Z, Hu H, Yu H, Yang X, Yang H, Ruan C, Wang Y, Tang J (2015) Relationship between leaf physiologic traits and canopy color indices during the leaf expansion period in an oak forest. Ecosphere 6:1–9

    Article  CAS  Google Scholar 

  • Maletha A, Maikhuri RK, Bargali SS (2020) Criteria and indicator for assessing threat on Himalayan birch (B. utilis) at timberline ecotone of Nanda Devi Biosphere Reserve: a world heritage site, Western Himalaya, India. Environm Sustain Indicators 8:100086

    Article  Google Scholar 

  • Menzel A, Fabian P (1999) Growing season extended in Europe. Nat 397:659–659

    Article  CAS  Google Scholar 

  • Menzel A, Sparks TH, Estrella N, Koch E, Aasa A, Ahas R, Alm-Kübler K, Bissolli P, Braslavská OG, Briede A, Chmielewski FM (2006) European phenological response to climate change matches the warming pattern. Glob Change Biol 12:1969–1976

    Article  Google Scholar 

  • Migliavacca M, Galvagno M, Cremonese E, Rossini M, Meroni M, Sonnentag O, Cogliati S, Manca G, Diotri F, Busetto L, Cescatti A (2011) Using digital repeat photography and eddy covariance data to model grassland phenology and photosynthetic CO2 uptake. Agric Forest Meteorol 151:1325–1337

    Article  Google Scholar 

  • Mir NA, Masoodi TH, Mir AA, Khan H, Sofi PA, Wani FJ, Hameed OB (2016) Phenology and growth performance of Himalayan birch (Betula utilis) in Kashmir Western Himalayas along the different altitudinal gradients. Indian J Agric Sci 86:1–86

    Google Scholar 

  • Mohapatra J, Singh CP, Hamid M, Verma A, Semwal SC, Gajmer B, Khuroo AA, Kumar A, Nautiyal MC, Sharma N, Pandya HA (2019) Modelling Betula utilis distribution in response to climate-warming scenarios in Hindu-Kush Himalaya using random forest. Biodivers & Conservation 28:2295–2317

    Article  Google Scholar 

  • Moriondo M, Leolini L, Staglianò N, Argenti G, Trombi G, Brilli L, Dibari C, Leolini C, Bindi M (2016) Use of digital images to disclose canopy architecture in olive tree. Sci Hort 209:1–13

    Article  Google Scholar 

  • Müller M, Schickhoff U, Scholten T, Drollinger S, Boehner J, Chaudhary RP (2016) How do soil properties affect alpine treelines? General principles in a global perspective and novel findings from Rolwaling himal, Nepal. Progr Phys Geogr 40:135–160

    Article  Google Scholar 

  • Nagai S, Akitsu T, Saitoh TM et al. (2018) 8 million phenological and sky images from 29 ecosystems from the Arctic to the tropics: the Phenological Eyes Network. Ecol Res 33:1091–1092

    Article  Google Scholar 

  • Parmesan C (2007) Influences of species, latitudes and methodologies on estimates of phenological response to global warming. Global Change Biol 13:1860–1872

    Article  Google Scholar 

  • Pellerin M, Delestrade A, Mathieu G, Rigault O, occoz, NG (2012) Spring tree phenology in the Alps: effects of air temperature, altitude and local topography. Eur J Forest Res 131:1957–1965

  • Peltoniemi M, Aurela M, Böttcher K, Kolari P, Loehr J, Hokkanen T, Karhu J, Linkosalmi M, Tanis CM, Metsämäki S, Tuovinen JP (2018) Networked web-cameras monitor congruent seasonal development of birches with phenological field observations. Agric Forest Meteorol 249:335–347

    Article  Google Scholar 

  • Pennekamp F, Schtickzelle N (2013) Implementing image analysis in laboratory-based experimental systems for ecology and evolution: a hands-on guide. Methods Ecol Evol 4:483–492

    Article  Google Scholar 

  • Petach AR, Toomey M, Aubrecht DM, Richardson AD (2014) Monitoring vegetation phenology using an infrared-enabled security camera. Agric Forest Meteorol 195:143–151

    Article  Google Scholar 

  • Polunin O, Stainton A (1984) Flowers of the Himalaya. Oxford University Press pp 374

  • R Core Team (2020) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. Available at https://www.R-project.org. Accessed on 12 May 2020.

  • Rai ID, Bharti RR, Adhikari BS, Rawat GS (2013) Structure and functioning of timberline vegetation in the Western Himalaya: a case study. In Ning W, Rawat GS, Joshi S, Ismail M, Sharma E (eds) High-altitude rangelends and their interfaces in the Hindu Kush Himalayas. ICIMOD, Kathmandu, pp. 91–107

    Google Scholar 

  • Ranjitkar S, Luedeling E, Shrestha KK, Guan K, Xu J (2013) Flowering phenology of tree rhododendron along an elevation gradient in two sites in the Eastern Himalayas. Int J Biometeorol 57:225–240

    Article  PubMed  Google Scholar 

  • Rawal RS, Bankoti NS, Samant SS, Pangtey YP (1991) Phenology of tree layer species from the timber line around Kumaun in Central Himalaya, India. Vegetatio 93:108–118

    Article  Google Scholar 

  • Richardson AD, Bailey AS, Denny EG, Martin CW, O'Keefe J (2006) Phenology of a northern hardwood forest canopy. Global Change Biol 12:1174–1188

    Article  Google Scholar 

  • Richardson AD, Hufkens K, Milliman T, Aubrecht DM, Chen M, Gray JM, Johnston MR, Keenan TF, Klosterman ST, Kosmala M, Melaas EK (2018a) Tracking vegetation phenology across diverse North American biomes using PhenoCam imagery. Sci Data 5:180028

    Article  PubMed  PubMed Central  Google Scholar 

  • Richardson AD, Hufkens K, Milliman T, Frolking S (2018b) Intercomparison of phenological transition dates derived from the PhenoCam Dataset V1.0 and MODIS satellite remote sensing. Sci Rep 8:1–12

    Article  Google Scholar 

  • Richardson AD, Jenkins JP, Braswell BH, Hollinger DY, Ollinger SV, Smith ML (2007) Use of digital webcam images to track spring green-up in a deciduous broadleaf forest. Oecologia 152:323–334

    Article  PubMed  Google Scholar 

  • Seyednasrollah B, Young AM, Hufkens K, Milliman T, Friedl MA, Frolking S, Richardson AD (2019) Tracking vegetation phenology across diverse biomes using Version 2.0 of the PhenoCam Dataset. Sci Data 22:1–11

    Google Scholar 

  • Sharma A, Batish DR, Uniyal SK (2020) Documentation and validation of climate change perception of an ethnic community of the western Himalaya. Environm Monit Assessm 192:552

    Article  Google Scholar 

  • Shekhar M, Bhardwaj A, Singh S, Ranhotra PS, Bhattacharyya A, Pal AK, Roy I, Martín-Torres FJ, Zorzano MP (2017) Himalayan glaciers experienced significant mass loss during later phases of little ice age. Sci Rep 7:1–14

    Article  CAS  Google Scholar 

  • Shrestha UB, Gautam S, Bawa KS (2012) Widespread climate change in the Himalayas and associated changes in local ecosystems. PloS One 7:e36741

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Singh KP, Kushwaha CP (2006) Diversity of flowering and fruiting phenology of trees in a tropical deciduous forest in India. Ann Bot (Oxford) 97:265–276

    Article  CAS  Google Scholar 

  • Singh SP, Thadani R (2015) Complexities and controversies in Himalayan research: a call for collaboration and rigor for better data. Mountain Res Developm 35:401–419

    Article  CAS  Google Scholar 

  • Sonnentag O, Hufkens K, Teshera-Sterne C, Young AM, Friedl M, Braswell BH, Milliman T, O’Keefe J, Richardson AD (2012) Digital repeat photography for phenological research in forest ecosystems. Agric Forest Meteorol 152:159–77

    Article  Google Scholar 

  • Thakur PS, Dutt V, Thakur A (2008) Impact of inter-annual climate variability on the phenology of eleven multipurpose tree species. Curr Sci 94:1053–1058

    Google Scholar 

  • Uniyal SK, Jaryan V, Singh RD (2017) Digital images for plant phenology documentation. Natl Acad Sci Lett 40:135–139

    Article  Google Scholar 

  • Uniyal SK, Uniyal A (2009) Climate change and large-scale degradation of spruce: common pattern across the globe. Clim Res 38:261–263

    Article  Google Scholar 

  • Walther GR, Post E, Convey P, Menzel A, Parmesan C, Beebee TJ, Fromentin JM, Hoegh-Guldberg O, Bairlein F (2002) Ecological responses to recent climate change. Nature 416:389–395

    Article  CAS  PubMed  Google Scholar 

  • Wang S, Wang X, Chen G, Yang Q, Wang B, Ma Y, Shen M (2017) Complex responses of spring alpine vegetation phenology to snow cover dynamics over the Tibetan Plateau, China. Sci Total Environ 593:449–461

    Article  PubMed  Google Scholar 

  • Wheeler JA, Cortés AJ, Sedlacek J, Karrenberg S, van Kleunen M, Wipf S, Hoch G, Bossdorf O, Rixen C (2016) The snow and the willows: earlier spring snowmelt reduces performance in the low-lying alpine shrub Salix herbacea. J Ecol 104:1041–1050

    Article  CAS  Google Scholar 

  • White MA, Running SW, Thornton PE (1999) The impact of growing-season length variability on carbon assimilation and evapotranspiration over 88 years in the eastern US deciduous forest. Int J Biometeorol 42:139–145

    Article  CAS  PubMed  Google Scholar 

  • Winkler DE, Butz RJ, Germino MJ, Reinhardt K, Kueppers LM (2018) Snowmelt timing regulates community composition, phenology, and physiological performance of alpine plants. Frontiers Pl Sci 9:1140

    Article  Google Scholar 

  • Xie Y, Wang X, Wilson AM, Silander Jr JA (2018a) Predicting autumn phenology: how deciduous tree species respond to weather stressors. Agric Forest Meteorol 250:127–137

    Article  Google Scholar 

  • Xie Y, Civco DL, Silander Jr JA (2018b) Species-specific spring and autumn leaf phenology captured by time-lapse digital cameras. Ecosphere 9:e02089

    Article  Google Scholar 

  • Xu J, Grumbine RE (2014) Building ecosystem resilience for climate change adaptation in the Asian highlands. Wiley Interdisciplinary Reviews: Climate Change 5:709–718

    Google Scholar 

  • Xu J, Grumbine RE, Shrestha A, Eriksson M, Yang X, Wang YU, Wilkes A (2009) The melting Himalayas: cascading effects of climate change on water, biodiversity, and livelihoods. Conservation Biol 23:520–530

    Article  CAS  Google Scholar 

  • Yang H, Yang X, Heskel M, Sun S, Tang J (2017) Seasonal variations of leaf and canopy properties tracked by ground-based NDVI imagery in a temperate forest. Sci Rep 7:1–10

    Google Scholar 

  • Yu H, Luedeling E, Xu J (2010) Winter and spring warming result in delayed spring phenology on the Tibetan Plateau. Proc Natl Acad Sci USA 107:22151–22156

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Yu L. Liu T, Bu K, Yan F, Yang J, Chang L, Zhang S (2017) Monitoring the long term vegetation phenology change in Northeast China from 1982 to 2015. Sci Rep 7:1–9

    Google Scholar 

  • Zhang Q, Kong D, Shi P, Singh VP, Sun P (2018) Vegetation phenology on the Qinghai-Tibetan Plateau and its response to climate change (1982–2013). Agric Forest Meteorol 248:408–417

    Article  Google Scholar 

Download references

Acknowledgements

The authors are thankful to Dr Sanjay Kumar, Director CSIR-IHBT, Palampur for providing necessary facilities and support. We thank the Ministry of Environment, Forests and Climate Change for providing financial support through the National Mission on Himalayan Studies project (GAP-0199). Thanks are also due to Ankush Dehlia for his immense help during image processing. We thank the Editor-in-Chief and reviewers of the manuscript whose comments helped in improving the earlier draft of the manuscript. The staff members of the Environmental Technology Division are acknowledged for their support and valuable suggestions.

Funding

National Mission on Himalayan Studies, GBP National Institute of Himalayan Environment, Ministry of Environment, Forests & Climate Change

Author information

Authors and Affiliations

Authors

Contributions

Rohit Sharma carried out surveys and installed the camera. Sanjay Kr. Uniyal designed the research and guided the fieldwork. Both authors contributed equally to the analyses and writing of the manuscript. Shalinder Kaur edited the manuscript and helped with the analyses.

Corresponding author

Correspondence to Sanjay Kr. Uniyal.

Ethics declarations

Conflict of interest

The authors declare no conflicts of interest

Additional information

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary Information

ESM 1

(DOCX 4579 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Sharma, R., Kaur, S. & Uniyal, S.K. Tracking the seasonal dynamics of Himalayan birch using a time-lapse camera. Folia Geobot 56, 125–138 (2021). https://doi.org/10.1007/s12224-021-09394-8

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s12224-021-09394-8

Keywords

Navigation