High-Resolution UAV Imagery and Ground Truth Tree Data of Deciduous Forests in Fruška gora National Park, Serbia

<p><strong>Study Area</strong><br>The imagery covers a section of the&nbsp;<strong>Fru&scaron;ka Gora National Park</strong>&nbsp;in Serbia. More than 90% of the area is covered by deciduous forests at elevations above 300 m. The forest primarily comprises mixed stands with the following dominant species:&nbsp;<strong><em>Quercus petraea</em>, <em>Tilia </em>spp., <em>Carpinus betulus</em>&nbsp;</strong>and<strong>&nbsp;<em>Fagus sylvatica</em></strong>.<br>The park's highest peak is 539 meters above sea level. More than 80% of the forest is of coppice origin, and it is a&nbsp;<strong>managed forest</strong>. The imagery captures forest stands of varying ages, from very young to old-growth stands. Ground truth data focuses on stands more than 70 years old.</p> <p><strong>Data Collection Overview</strong><br><strong>1. RGB Imagery</strong></p> <ul> <li><strong>Equipment</strong>: High-resolution RGB images were captured using a&nbsp;<strong>Sony UMC-R10C camera</strong>&nbsp;mounted on a&nbsp;<strong>Quantum Systems Trinity F90+ UAV</strong>.</li> <li><strong>Altitude</strong>: 134 meters.</li> <li><strong>Ground Sampling Distance (GSD)</strong>: 4.13 cm/pix.</li> <li><strong>Coordinate System:</strong>&nbsp;Processed in&nbsp;<strong>EPSG:32634</strong>&nbsp;(WGS 84 / UTM zone 34N).</li> </ul> <p><strong>2. Multispectral (MS) Imagery</strong></p> <ul> <li><strong>Equipment</strong>: Multispectral data captured with a&nbsp;<strong>Dual MicaSense Camera</strong>, covering&nbsp;<strong>10 spectral bands</strong>&nbsp;spanning visible, red-edge, and near-infrared regions.</li> <li><strong>Altitude</strong>: 135 meters.</li> <li><strong>Ground Sampling Distance (GSD)</strong>: 9.35 cm/pix.</li> <li><strong>Coordinate System:</strong>&nbsp;Processed in&nbsp;<strong>EPSG:4326 </strong>(WGS 84)<strong>.</strong></li> </ul> <p><strong>3. Ground Truth Tree Data</strong></p> <ul> <li><strong>Sampling Methodology</strong>: Data was collected along transects representing monodominant or mixed forest<span> stands</span>, focusing on&nbsp;<em><strong>Quercus petraea</strong></em>,&nbsp;<em><strong>Fagus sylvatica</strong></em>, and&nbsp;<strong><em>Tilia </em>spp.</strong></li> <li><strong>Tree Count</strong>: Approximately&nbsp;<strong>120 trees</strong>&nbsp;were geolocated and measured.</li> </ul> <p><strong>Measurement Tools and Procedures</strong>:</p> <ul> <li><strong>Geographic Coordinates</strong>: Recorded with a&nbsp;<strong>Garmin eTrex 20 GPS</strong>&nbsp;and manually corrected using RGB aerial imagery for improved precision.</li> <li><strong>Tree Crowns</strong>: Delineated manually in&nbsp;<strong>QGIS 3.38.3</strong>&nbsp;using RGB imagery.</li> <li><strong>Tree Diameter</strong>: Measured at&nbsp;<strong>breast height (1.3m)</strong>&nbsp;using a diameter tape.</li> <li><strong>Tree Height</strong>: Measured using a&nbsp;<strong>Hagl&ouml;f EC II-D electronic clinometer</strong>.</li> </ul> <p><strong>Tree Attributes Recorded</strong>:</p> <ul> <li><span>Species latin name</span>.</li> <li>Diameter at breast height (DBH).</li> <li>Tree height (H).</li> <li>Geographic coordinates (center of the tree crown).</li> <li>Elevation.</li> </ul> <p><strong>Temporal Coverage</strong></p> <ul> <li>Field data collection occurred during&nbsp;<strong>autumn 2024</strong>.</li> </ul>