{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,17]],"date-time":"2026-03-17T10:33:19Z","timestamp":1773743599278,"version":"3.50.1"},"reference-count":87,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2018,9,2]],"date-time":"2018-09-02T00:00:00Z","timestamp":1535846400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100016077","name":"EU","doi-asserted-by":"publisher","award":["LIFE14 ENV\/IT\/000414"],"award-info":[{"award-number":["LIFE14 ENV\/IT\/000414"]}],"id":[{"id":"10.13039\/100016077","id-type":"DOI","asserted-by":"publisher"}]},{"name":"ERASMUS MEDfOR","award":["520137-1-2011-1-PT-ERA MUNDUS-EMMC"],"award-info":[{"award-number":["520137-1-2011-1-PT-ERA MUNDUS-EMMC"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Forest canopy gaps are important to ecosystem dynamics. Depending on tree species, small canopy openings may be associated with intra-crown porosity and with space among crowns. Yet, literature on the relationships between very fine-scaled patterns of canopy openings and biodiversity features is limited. This research explores the possibility of: (1) mapping forest canopy gaps from a very high spatial resolution orthomosaic (10 cm), processed from a versatile unmanned aerial vehicle (UAV) imaging platform, and (2) deriving patch metrics that can be tested as covariates of variables of interest for forest biodiversity monitoring. The orthomosaic was imaged from a test area of 240 ha of temperate deciduous forest types in Central Italy, containing 50 forest inventory plots each of 529 m2 in size. Correlation and linear regression techniques were used to explore relationships between patch metrics and understory (density, development, and species diversity) or forest habitat biodiversity variables (density of micro-habitat bearing trees, vertical species profile, and tree species diversity). The results revealed that small openings in the canopy cover (75% smaller than 7 m2) can be faithfully extracted from UAV red, green, and blue bands (RGB) imagery, using the red band and contrast split segmentation. The strongest correlations were observed in the mixed forests (beech and turkey oak) followed by intermediate correlations in turkey oak forests, followed by the weakest correlations in beech forests. Moderate to strong linear relationships were found between gap metrics and understory variables in mixed forest types, with adjusted R2 from linear regression ranging from 0.52 to 0.87. Equally strong correlations in the same forest types were observed for forest habitat biodiversity variables (with adjusted R2 ranging from 0.52 to 0.79), with highest values found for density of trees with microhabitats and vertical species profile. In conclusion, this research highlights that UAV remote sensing can potentially provide covariate surfaces of variables of interest for forest biodiversity monitoring, conventionally collected in forest inventory plots. By integrating the two sources of data, these variables can be mapped over small forest areas with satisfactory levels of accuracy, at a much higher spatial resolution than would be possible by field-based forest inventory solely.<\/jats:p>","DOI":"10.3390\/rs10091397","type":"journal-article","created":{"date-parts":[[2022,5,19]],"date-time":"2022-05-19T21:56:59Z","timestamp":1652997419000},"page":"1397","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":45,"title":["UAV Remote Sensing for Biodiversity Monitoring: Are Forest Canopy Gaps Good Covariates?"],"prefix":"10.3390","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1178-3229","authenticated-orcid":false,"given":"Martin B.","family":"Bagaram","sequence":"first","affiliation":[{"name":"School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, WA 98195, USA"}]},{"given":"Diego","family":"Giuliarelli","sequence":"additional","affiliation":[{"name":"Department for Innovation in Biological, Agro-Food and Forest System, Universit\u00e0 degli Studi della Tuscia, S. Camillo de Lellis snc, 01100 Viterbo, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0669-5726","authenticated-orcid":false,"given":"Gherardo","family":"Chirici","sequence":"additional","affiliation":[{"name":"Department of Agricultural, Food and Forestry System, Universit\u00e0 degli Studi di Firenze, Via San Bonaventura 13, 50145 Florence, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4590-827X","authenticated-orcid":false,"given":"Francesca","family":"Giannetti","sequence":"additional","affiliation":[{"name":"Department of Agricultural, Food and Forestry System, Universit\u00e0 degli Studi di Firenze, Via San Bonaventura 13, 50145 Florence, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9064-0903","authenticated-orcid":false,"given":"Anna","family":"Barbati","sequence":"additional","affiliation":[{"name":"Department for Innovation in Biological, Agro-Food and Forest System, Universit\u00e0 degli Studi della Tuscia, S. Camillo de Lellis snc, 01100 Viterbo, Italy"}]}],"member":"1968","published-online":{"date-parts":[[2018,9,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"725","DOI":"10.1007\/s11676-014-0521-7","article-title":"A review of the roles of forest canopy gaps","volume":"25","author":"Muscolo","year":"2014","journal-title":"J. For. Res."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"663","DOI":"10.1016\/j.foreco.2013.09.006","article-title":"Regeneration in canopy gaps of tierra-firme forest in the Peruvian Amazon: Comparing reduced impact logging and natural, unmanaged forests","volume":"310","author":"Karsten","year":"2013","journal-title":"For. Ecol. Manag."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1016\/j.foreco.2013.11.004","article-title":"Growth releases across a natural canopy gap-forest gradient in old-growth forests","volume":"313","author":"Stan","year":"2014","journal-title":"For. Ecol. 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