{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T03:44:59Z","timestamp":1790135099062,"version":"4.0.1"},"reference-count":50,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2026,3,6]],"date-time":"2026-03-06T00:00:00Z","timestamp":1772755200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Tianshan Talent Development Program","award":["2022TSYCCX0006"],"award-info":[{"award-number":["2022TSYCCX0006"]}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["42371389"],"award-info":[{"award-number":["42371389"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Western Young Scholars Project of the Chinese Academy of Sciences","award":["2022-XBQNXZ-001"],"award-info":[{"award-number":["2022-XBQNXZ-001"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Plants"],"abstract":"<jats:p>The expansion of the invasive species Pedicularis kansuensis threatens the ecological integrity of alpine wetlands, particularly in the Bayinbuluke, northwestern China. However, operational monitoring remains challenging. Conventional indices often lack specificity in heterogeneous alpine backgrounds, while deep learning models are typically too data-intensive to support consistent, multi-year mapping. To develop a rapid, reliable, and operational method for monitoring this invader, we proposed a novel, species-specific spectral index, the Pedicularis kansuensis Index (PKI), using the blue, green, and red-edge bands of high-resolution (3 m) PlanetScope imagery. The PKI constructs a robust target signal by integrating distinct spectral features derived from in situ hyperspectral measurement with a grayscale morphological opening (GrMO) refinement to suppress background noise. A comprehensive validation against seven established benchmarks indices (e.g., NDVI, RI, and ARI) demonstrated the superior performance of PKI across the central alpine wetlands of Bayinbuluke (2841 km2). It achieved the highest separability with an M-statistic of 1.36. Furthermore, the index attained an overall accuracy of 93.52% (95% CI: 92.3\u201394.7%), and an F1-score of 93.28% (95% CI: 92.0\u201394.5%), effectively minimizing confusion with co-occurring native vegetation and background. Applying this framework to a five-year time series (2021\u20132025) revealed a distinct cycle of outbreaks and relaxation. Specifically, the invaded area increased to 2168 ha in 2022, then decreased to 160 ha in 2025. Spatial analysis further identified stable invasion hotspots of 161.6 ha, highlighting key targets for long-term containment. Meanwhile, 94.4% of the invaded area was transient, lasting only one year (4824.7 ha). These results confirm that the PKI is a physically interpretable, accurate, and computationally efficient tool for monitoring invasive species in heterogeneous alpine environments. It facilitates timely and targeted ecosystem management.<\/jats:p>","DOI":"10.3390\/plants15050806","type":"journal-article","created":{"date-parts":[[2026,3,6]],"date-time":"2026-03-06T11:05:44Z","timestamp":1772795144000},"page":"806","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Monitoring the Spatiotemporal Dynamics of Invasive Pedicularis kansuensis in Bayinbuluke Alpine Wetlands: A Novel Spectral Index Framework Using PlanetScope Time Series (2021\u20132025)"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0009-0006-4014-289X","authenticated-orcid":false,"given":"Enzhao","family":"Zhu","sequence":"first","affiliation":[{"name":"State Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China"},{"name":"University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9091-6033","authenticated-orcid":false,"given":"Alim","family":"Samat","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China"},{"name":"University of Chinese Academy of Sciences, Beijing 100049, China"},{"name":"China-Kazakhstan Joint Laboratory for Remote Sensing Technology and Application, Al-Farabi Kazakh National University, Almaty 050012, Kazakhstan"},{"name":"Xinjiang Key Laboratory of RS & GIS Application, Urumqi 830011, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-7492-263X","authenticated-orcid":false,"given":"Wenbo","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Electrical, Computer and Biomedical Engineering, University of Pavia, 27100 Pavia, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-5331-2701","authenticated-orcid":false,"given":"Kaiyue","family":"Luo","sequence":"additional","affiliation":[{"name":"College of Surveying and Geoinformatics, Tongji University, Shanghai 200070, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"15972","DOI":"10.1038\/ncomms15972","article-title":"Iron-mediated soil carbon response to water-table decline in an alpine wetland","volume":"8","author":"Wang","year":"2017","journal-title":"Nat. Commun."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"111403","DOI":"10.1016\/j.ecolind.2023.111403","article-title":"Effects of driving factors on water supply function under different basins and spatial scale in Zoige alpine wetland, China","volume":"158","author":"Yu","year":"2024","journal-title":"Ecol. Indic."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"108302","DOI":"10.1016\/j.ecolind.2021.108302","article-title":"Change in grass hill size can signal species diversity changes and ecosystem state transitions during alpine wetland degradation","volume":"132","author":"He","year":"2021","journal-title":"Ecol. Indic."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"106704","DOI":"10.1016\/j.catena.2022.106704","article-title":"Potential role of high-altitude wetlands in preservation of plant biodiversity under changing climatic conditions in the arid Eastern Pamir","volume":"220","author":"Chachulski","year":"2023","journal-title":"Catena"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"397","DOI":"10.1038\/s43247-024-01562-w","article-title":"Alpine wetlands degradation leads to soil nutrient imbalances that affect plant growth and microbial diversity","volume":"5","author":"Xu","year":"2024","journal-title":"Commun. Earth Environ."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"658","DOI":"10.1007\/s11629-013-2562-3","article-title":"Degradation of wetlands on the Qinghai-Tibet Plateau: A comparison of the effectiveness of three indicators","volume":"10","author":"Gao","year":"2013","journal-title":"J. Mt. Sci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"316","DOI":"10.1016\/j.ecolind.2017.06.059","article-title":"Marsh wetland degradation risk assessment and change analysis: A case study in the Zoige Plateau, China","volume":"82","author":"Jiang","year":"2017","journal-title":"Ecol. Indic."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"111414","DOI":"10.1016\/j.ecolind.2023.111414","article-title":"Evaluation of alpine wetland ecological degradation based on alpine wetland degradation index: A case study in the first meander of the Yellow River","volume":"158","author":"Zhao","year":"2024","journal-title":"Ecol. Indic."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"431","DOI":"10.1080\/07352680490514673","article-title":"Causes and consequences of invasive plants in wetlands: Opportunities, opportunists, and outcomes","volume":"23","author":"Zedler","year":"2004","journal-title":"critical Rev. Plant Sci."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Zhu, E., Samat, A., Li, E., Xu, R., Li, W., and Li, W. (2025). Adversarial Positive-Unlabeled Learning-Based Invasive Plant Detection in Alpine Wetland Using Jilin-1 and Sentinel-2 Imageries. Remote Sens., 17.","DOI":"10.3390\/rs17061041"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Wu, S., Dong, S., Wang, Z., Li, S., Ma, C., and Li, Z. (2024). Response of species dominance and niche of plant community to wetland degradation along alpine lake riparian. Front. Plant Sci., 15.","DOI":"10.3389\/fpls.2024.1352834"},{"key":"ref_12","unstructured":"POWO (2026, February 22). Plants of the World Online. Available online: https:\/\/powo.science.kew.org\/."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"133979","DOI":"10.1016\/j.scitotenv.2019.133979","article-title":"Moving north in China: The habitat of Pedicularis kansuensis in the context of climate change","volume":"697","author":"Wang","year":"2019","journal-title":"Sci. Total Environ."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"226","DOI":"10.1016\/j.pld.2018.07.005","article-title":"Fast and abundant in vitro spontaneous haustorium formation in root hemiparasitic plant Pedicularis kansuensis Maxim. (Orobanchaceae)","volume":"40","author":"Xiang","year":"2018","journal-title":"Plant Divers."},{"key":"ref_15","first-page":"1","article-title":"Effect of Pedicularis kansuensis invasion on plant community characteristics in Bayanbulak grassland","volume":"41","author":"Huang","year":"2024","journal-title":"Pratacultural Science. Pratacultural Sci."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"453","DOI":"10.1007\/s40333-016-0004-0","article-title":"Identity and distribution of weedy Pedicularis kansuensis Maxim. (Orobanchaceae) in Tianshan Mountains of Xinjiang: Morphological, anatomical and molecular evidence","volume":"8","author":"Sui","year":"2016","journal-title":"J. Arid Land"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"649","DOI":"10.1093\/jpe\/rtw005","article-title":"Satellite remote sensing of grasslands: From observation to management","volume":"9","author":"Ali","year":"2016","journal-title":"J. Plant Ecol."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Wang, W., Tang, J., Zhang, N., Wang, Y., Xu, X., and Zhang, A. (2023). Spatiotemporal Pattern of Invasive Pedicularis in the Bayinbuluke Land, China, during 2019\u20132021: An Analysis Based on PlanetScope and Sentinel-2 Data. Remote Sens., 15.","DOI":"10.3390\/rs15184383"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1016\/j.pce.2018.12.004","article-title":"Advancements in satellite remote sensing for mapping and monitoring of alien invasive plant species (AIPs)","volume":"112","author":"Royimani","year":"2019","journal-title":"Phys. Chem. Earth Parts A\/B\/C"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Zhao, J., Li, K., Zhang, J., Liu, Y., and Li, X. (2024). Mapping Invasive Species Pedicularis and Background Grassland Using UAV and Machine Learning Algorithms. Drones, 8.","DOI":"10.3390\/drones8110639"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Wang, W., Tang, J., Zhang, N., Xu, X., Zhang, A., and Wang, Y. (2022). Automated detection method to extract Pedicularis based on UAV images. Drones, 6.","DOI":"10.3390\/drones6120399"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1632","DOI":"10.1111\/2041-210X.13256","article-title":"Applications for deep learning in ecology","volume":"10","author":"Christin","year":"2019","journal-title":"Methods Ecol. Evol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1109\/MGRS.2017.2762307","article-title":"Deep learning in remote sensing: A comprehensive review and list of resources","volume":"5","author":"Zhu","year":"2017","journal-title":"IEEE Geosci. Remote Sens. Mag."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"111402","DOI":"10.1016\/j.rse.2019.111402","article-title":"Remote sensing for agricultural applications: A meta-review","volume":"236","author":"Weiss","year":"2020","journal-title":"Remote Sens. Environ."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"477","DOI":"10.1038\/s43017-022-00298-5","article-title":"Optical vegetation indices for monitoring terrestrial ecosystems globally","volume":"3","author":"Zeng","year":"2022","journal-title":"Nat. Rev. Earth Environ."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1102","DOI":"10.1016\/j.rse.2010.12.015","article-title":"Satellite passive microwave remote sensing for monitoring global land surface phenology","volume":"115","author":"Jones","year":"2011","journal-title":"Remote Sens. Environ."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1411","DOI":"10.1007\/s10530-013-0578-9","article-title":"Remote detection of invasive plants: A review of spectral, textural and phenological approaches","volume":"16","author":"Bradley","year":"2014","journal-title":"Biol. Invasions"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"0510","DOI":"10.34133\/remotesensing.0510","article-title":"SAI: A Spartina alterniflora Index Based on Sentinel-2 Multispectral Imagery for Spartina alterniflora Mapping","volume":"5","author":"Zuo","year":"2025","journal-title":"J. Remote Sens."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1999","DOI":"10.1002\/qj.3803","article-title":"The ERA5 global reanalysis","volume":"146","author":"Hersbach","year":"2020","journal-title":"Q. J. R. Meteorol. Soc."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"105519","DOI":"10.1016\/j.compag.2020.105519","article-title":"UAV and a deep convolutional neural network for monitoring invasive alien plants in the wild","volume":"174","author":"Qian","year":"2020","journal-title":"Comput. Electron. Agric."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"112061","DOI":"10.1016\/j.ecolind.2024.112061","article-title":"Monitoring the spatial\u2013temporal distribution of invasive plant in urban water using deep learning and remote sensing technology","volume":"162","author":"Hao","year":"2024","journal-title":"Ecol. Indic."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"101989","DOI":"10.1016\/j.ecoinf.2023.101989","article-title":"Modeling and detection of invasive trees using UAV image and machine learning in a subtropical forest in Brazil","volume":"74","author":"Eugenio","year":"2023","journal-title":"Ecol. Inform."},{"key":"ref_33","first-page":"1099","article-title":"Impacts of climatic changes as well as seed germination characteristics on the population expansion of Pedicularis verticillata","volume":"22","author":"Sui","year":"2013","journal-title":"Ecol. Environ. Sci"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"280","DOI":"10.1016\/j.catena.2018.07.021","article-title":"Soil quality assessment under different land uses in an alpine grassland","volume":"171","author":"Yu","year":"2018","journal-title":"Catena"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"383","DOI":"10.1659\/0276-4741(2002)022[0383:HICTBA]2.0.CO;2","article-title":"Human-induced changes to biodiversity and alpine pastureland in the bayanbulak region of the east tienshan mountains","volume":"22","author":"Zhang","year":"2002","journal-title":"Mt. Res. Dev."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Hu, L., Wang, J., Wang, X., Zhang, D., Sun, Y., Lu, T., and Shi, W. (2024). Development of SSR markers and evaluation of genetic diversity of endangered plant Saussurea involucrata. Biomolecules, 14.","DOI":"10.3390\/biom14081010"},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Li, W.-J., Sui, X.-L., Kuss, P., Liu, Y.-Y., Li, A.-R., and Guan, K.-Y. (2016). Long-distance dispersal after the Last Glacial Maximum (LGM) led to the disjunctive distribution of Pedicularis kansuensis (Orobanchaceae) between the Qinghai-Tibetan Plateau and Tianshan region. PLoS ONE, 11.","DOI":"10.1371\/journal.pone.0165700"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"112586","DOI":"10.1016\/j.rse.2021.112586","article-title":"A global analysis of the temporal availability of PlanetScope high spatial resolution multi-spectral imagery","volume":"264","author":"Roy","year":"2021","journal-title":"Remote Sens. Environ."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"678","DOI":"10.1016\/j.isprsjprs.2025.06.036","article-title":"Accuracy assessment of PlanetScope SuperDove products for aquatic reflectance retrieval over Brazilian inland and coastal waters","volume":"227","author":"Chasles","year":"2025","journal-title":"ISPRS J. Photogramm. Remote Sens."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"121768","DOI":"10.1016\/j.envres.2025.121768","article-title":"Insights into the impact of light-absorbing impurities on radiative forcing and snowmelt in the Ili Basin in Central Asia","volume":"279","author":"Wu","year":"2025","journal-title":"Environ. Res."},{"key":"ref_41","unstructured":"Vincent, L. (1993, January 12\u201314). Grayscale area openings and closings, their efficient implementation and applications. Proceedings of the First Workshop on Mathematical Morphology and Its Applications to Signal Processing, Barcelona, Spain."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1046\/j.1469-8137.1999.00424.x","article-title":"Assessing leaf pigment content and activity with a reflectometer","volume":"143","author":"Gamon","year":"1999","journal-title":"New Phytol."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"127","DOI":"10.1016\/0034-4257(79)90013-0","article-title":"Red and photographic infrared linear combinations for monitoring vegetation","volume":"8","author":"Tucker","year":"1979","journal-title":"Remote Sens. Environ."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"289","DOI":"10.1016\/S0034-4257(96)00072-7","article-title":"Use of a green channel in remote sensing of global vegetation from EOS-MODIS","volume":"58","author":"Gitelson","year":"1996","journal-title":"Remote Sens. Environ."},{"key":"ref_45","unstructured":"Barnes, E., Clarke, T., Richards, S., Colaizzi, P., Haberland, J., Kostrzewski, M., Waller, P., Choi, C., Riley, E., and Thompson, T. (2000, January 16\u201319). Coincident detection of crop water stress, nitrogen status and canopy density using ground based multispectral data. Proceedings of the Fifth International Conference on Precision Agriculture, Bloomington, MN, USA."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"271","DOI":"10.1078\/0176-1617-00887","article-title":"Relationships between leaf chlorophyll content and spectral reflectance and algorithms for non-destructive chlorophyll assessment in higher plant leaves","volume":"160","author":"Gitelson","year":"2003","journal-title":"J. Plant Physiol."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"L08403","DOI":"10.1029\/2005GL022688","article-title":"Remote estimation of canopy chlorophyll content in crops","volume":"32","author":"Gitelson","year":"2005","journal-title":"Geophys. Res. Lett."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"38","DOI":"10.1562\/0031-8655(2001)074<0038:OPANEO>2.0.CO;2","article-title":"Optical properties and nondestructive estimation of anthocyanin content in plant leaves","volume":"74","author":"Gitelson","year":"2001","journal-title":"Photochem. Photobiol."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"603","DOI":"10.1038\/nmeth.3945","article-title":"Classification evaluation: It is important to understand both what a classification metric expresses and what it hides","volume":"13","author":"Lever","year":"2016","journal-title":"Nat. Methods"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"672","DOI":"10.1109\/36.297984","article-title":"Detection of forests using mid-IR reflectance: An application for aerosol studies","volume":"32","author":"Kaufman","year":"2002","journal-title":"IEEE Trans. Geosci. Remote Sens."}],"container-title":["Plants"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2223-7747\/15\/5\/806\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,6]],"date-time":"2026-03-06T11:43:57Z","timestamp":1772797437000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2223-7747\/15\/5\/806"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,6]]},"references-count":50,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2026,3]]}},"alternative-id":["plants15050806"],"URL":"https:\/\/doi.org\/10.3390\/plants15050806","relation":{},"ISSN":["2223-7747"],"issn-type":[{"value":"2223-7747","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,6]]}}}