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With the development of new imaging and near field remote sensing UAV technologies, the field of forest canopy and tree crown investigations in the context of rainforest ecology gained new perspectives in recent years. This study demonstrates the feasibility of structural analysis of canopy for the assessment of succession states of tropical lowland rainforests using a consumer UAV and open access ground reference data. Therefore, the canopy of 22 small-scale forest plots in the Ecuadorian Andes and the Mata Atlântica were captured with an UAV between October 2017 and February 2018. The fully remote image acquisition used automated flight plans consisting of crossed flights with different incident camera angles and did not require ground control points (GCP) as further ground reference. Photogrammetric Point Clouds (PPC), image meshes and crown height models (CHM) were created with Structure from Motion (SfM), combined with a Digital Terrain Model from the Shuttle Radar Topography Mission (SRTM), in order to analyze structural parameters of the canopy. The standard deviation of the height values of the PPC and the CHM differs statistically significant between succession stages. Investigation plots in climax or late succession show a mean PPCSD of 6.7 m with a standard error of 0,3 m. Plots in early succession show a PPCSD of 4.8 m with a standard error of 0.3 m and degraded plots show 2.8m with a standard error of 0.2m. This result proves the applicability of the proposed workflow under typical NGO conditions and other applied science research with limitations in budget and access to sophisticated survey equipment.
Diese Veröffentlichung stellt eine Ergänzung zum Artikel „Resilienz von naturnahen Mooren im Klimawandel – Fallbeispiele aus dem Biosphärenreservat Schorfheide-Chorin“ von Luthardt et al. (2023) im Themenheft "Moorschutz im Klimawandel" der Zeitschrift „Natur und Landschaft“ dar. Die Steckbriefe der Moore können als eigenständige, kurze Informationsquelle genutzt werden. Sie beinhalten Basisinformationen zum jeweiligen Standort. Die Abbildung und die Tabellen geben weitere Informationen zu den Wasserstufen, Bauwerten und Libellenvorkommen der untersuchten Moore und sind in Kombination mit den Steckbriefen der Moore und dem Artikel zu betrachten.
Forests are an important part of the ecosphere and have long been at the center of extensive research. For quantifying forest metrics on larger scales, remote sensing technologies have become important tools over the last decades. One of these tools is airborne lidar, which has enabled detailed analyses of canopy structures by providing three-dimensional point clouds of forests. Within such data sets, individual crown bodies can be detected and delineated, which is referred to as tree crown segmentation. However, among the few available algorithms the most sophisticated ones are also the most resource hungry. Another general issue with lidar point clouds is that their density can vary strongly between adjacent areas which also influences segmentation results. In this study a segmentation workflow from point cloud preparation to the evaluation of results was developed. Part of this workflow was a novel approach to removing undesired density patterns from point clouds, using detailed information on the measurement procedure. Also, a scalable segmentation algorithm, based on 3-dimensional mean shift clustering was implemented. It reached single-core runtimes of about 50 seconds ha -1 on point clouds with a density of 10 points m -2 . The segmentation results allowed for the estimation of stem diameter distributions for a temperate mixed forest stand. Overall, the presented workflow provides a solid basis for individual tree segmentation and can be further extended and scaled with relative ease.
Desde hace más de 2 500 años, el Quetzal Mesoamericano está presente en el arte
y las culturas de Mesoamérica. Como símbolo de la vida y la fertilidad, esta ave y su
plumaje fueron representados variadamente por los olmecas, los mayas y los aztecas.
Hoy en día, el quetzal es una especie bandera de la conservación internacional y
una especie característica de los bosques húmedos de montaña de Mesoamérica.
Desgraciadamente, éstos están cada vez más amenazados. La historia cultural, la
historia natural y la conservación se entrelazan de manera única en una de las aves
más bellas del mundo.