{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,18]],"date-time":"2026-05-18T10:19:01Z","timestamp":1779099541695,"version":"3.51.4"},"reference-count":82,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2023,1,17]],"date-time":"2023-01-17T00:00:00Z","timestamp":1673913600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Structural diversity is recognized as a complementary aspect of biological diversity and plays a fundamental role in forest management, conservation, and restoration. Hence, the assessment of structural diversity has become a major effort in the primary international processes, dealing with biodiversity and sustainable forest management. Because of prohibitive costs associated with the ground measurements of forest structure, despite their high accuracy, space-borne polarization coherence tomography (PCT) can introduce an alternative approach given its ability to provide a vertical reflectivity profile and spatiotemporal resolutions related to detecting forest structural changes. In this study, for the first time ever, the potential of space-borne PCT was evaluated in a broad-leaved Hyrcanian forest of Iran over 308 circular sample plots with an area of 0.1 ha. Two aspects of horizontal structure diversity, including standard deviation of diameter at breast height (\u03c3dbh) and the number of trees (N), were predicted as important characteristics in wood production and biomass estimation. In addition, the performance of prediction algorithms, including multiple linear regression (MLR), k-nearest neighbors (k-NN), random forest (RF), and support vector regression (SVR) were compared. We addressed the issue of temporal decorrelation in space-borne PCT utilizing the single-pass TanDEM-X interferometer. The data were acquired in standard DEM mode with single polarization of HH. Consequently, airborne laser scanning (ALS) was used to estimate initial values of height hv and ground phase \u03c60. The Fourier\u2013Legendre series was used to approximate the relative reflectivity profile of each pixel. To link the relative reflectivity profile averaged within each plot with corresponding ground measurements of \u03c3dbh and N, thirteen geometrical and physical parameters were defined (P1\u2212P13). Leave-one-out cross validation (LOOCV) showed a better performance of k-NN than the other algorithms in predicting \u03c3dbh and N. It resulted in a relative root mean square error (rRMSE) of 32.80%, mean absolute error (MAE) of 4.69 cm, and R2* of 0.25 for \u03c3dbh, whereas only 22% of the variation in N was explained using the PCT algorithm with an rRMSE of 41.56%. This study revealed promising results utilizing TanDEM-X data even though the accuracy is still limited. Hence, an entire assessment of the used framework in characterizing the reflectivity profile and the possible effect of the scale is necessary for future studies.<\/jats:p>","DOI":"10.3390\/rs15030555","type":"journal-article","created":{"date-parts":[[2023,1,18]],"date-time":"2023-01-18T02:31:11Z","timestamp":1674009071000},"page":"555","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["First Demonstration of Space-Borne Polarization Coherence Tomography for Characterizing Hyrcanian Forest Structural Diversity"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6341-3887","authenticated-orcid":false,"given":"Maryam","family":"Poorazimy","sequence":"first","affiliation":[{"name":"Department of Electronics and Nanoengineering, Aalto University, 02150 Espoo, Finland"},{"name":"Department of Forestry, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan 49189-43464, Iran"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3868-8475","authenticated-orcid":false,"given":"Shaban","family":"Shataee","sequence":"additional","affiliation":[{"name":"Department of Forestry, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan 49189-43464, Iran"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hossein","family":"Aghababaei","sequence":"additional","affiliation":[{"name":"Department of Earth Observation Science, University of Twente, 7514AE Enschede, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Erkki","family":"Tomppo","sequence":"additional","affiliation":[{"name":"Department of Forest Sciences, University of Helsinki, 00014 Helsinki, Finland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jaan","family":"Praks","sequence":"additional","affiliation":[{"name":"Department of Electronics and Nanoengineering, Aalto University, 02150 Espoo, Finland"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,1,17]]},"reference":[{"key":"ref_1","first-page":"34","article-title":"Forest Structure: A Key to the Ecosystem","volume":"72","author":"Spies","year":"1998","journal-title":"Northwest Sci."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1007\/s10342-015-0927-6","article-title":"Characterization of the Structure, Dynamics, and Productivity of Mixed-Species Stands: Review and Perspectives","volume":"135","author":"Pretzsch","year":"2016","journal-title":"Eur. 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