| Autor: |
Pascu, Ionut Silviu, Alexandru-Claudiu Dobre, Zamfira, Virgil, Apostol, Ecaterina, Leca, Stefan, Pitar, Diana, Apostol, Bogdan, Chivulescu, Serban, Ciceu, Albert, Duro, Juan Garcia, Badea, Ovidiu |
| Rok vydání: |
2021 |
| DOI: |
10.6084/m9.figshare.13567031 |
| Popis: |
The current paper tested the hypothesis that TLS through its high accuracy, increased spatial resolution, portability, equivalenting în high temporal resolution, automated processing and unlimited revisiting capabilities of the scene once record ed, might represent the best available technology for phenological evaluation. Phenology observations represent one of the most accurate methods for evaluating the response of plant species to various climate conditions and climate changes. The main objective of this research was to identify the pattems pf early vegetation stages in the context of a reduced precipitation regime through terrestrial scanning technique. The research was carried out in a mixed forest stand ( Carpinus betulus, Acer campestre, Tilia cordata, Quercus robur) with the focus of more precisely identifying the pattem of early vegetation development. The phenological processes analysis was done at an increased spatial and temporal resolution, on specific horizontal layers by means of terrestrial laser scanning. With a daily cycle started in March, we maintained a constant scanning position as well as time of day and scanning resolution. Supervised thresholds have been set at the heights of separation between undergrowth, trunk and crown, and for each resulting layer coverage and density metrics as well as derived indices (Gap Fraction and Leaf Area Density) have been computed. For reference data, photos were interpreted as per the ICP Forests guideline. A sequential evolution was observed în all studied species. Hornbeam displayed a daily increase în LAD for all layers up until epicormic branches shadowing overtook the upper canopy visibility. Small-leaved lime showed a delay of almost 20 days in comparison to oak. Oak started with an abrupt 13% increase in foliage volume from the reference date, compared to the 3% increase în the small-leaved lime. Also, at the time of bud flushing of the small-leaved lime, the oak had already been through four similar stages (18-20-23%). Although not identica! to the historical data, analysed trends still fit the expected pattems. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
