Methodology for estimating defoliation of Quercus robur L. on the basis of reflectance analysis in the range of 0.64-0.73 µm

Ocena defoliacji koron jest użytecznym wskaźnikiem kondycji i żywotności drzew. W ramach projektu HESOFF podjęta została próba wypracowania metodyki oszacowania defoliacji drzewostanów dębu szypułkowego (Quercus robur) za pomocą analizy wielospektralnych zdjęć lotniczych wykonywanych z użyciem sześciokanałowej Platformy Wielosensorowej QUERCUS.6. Podczas cyklu wegetacyjnego (marzec-wrzesień 2015 r.) wykonane zostały zobrazowania lotnicze drzewostanów dębowych Płyty Krotoszyńskiej (zakres widzialny promieniowania elektromagnetycznego i bliska podczerwień). W badanych drzewostanach został oznaczony poziom defoliacji metodami terenowymi. Na podstawie fotografii wykonany został model wysokościowy pokrycia terenu oraz oznaczono niezacienioną część koron dębów. Dla 49 drzew o znanym poziomie defoliacji wykonano analizę PCA reflektancji uwzględniając odpowiednio oświetloną część ich koron, poziom defoliacji zmierzony in situ oraz model wysokościowy. Analiza wykazała silnie ujemną korelację poziomu defoliacji oraz reflektancji w kanale optycznym 0,73 µm. Na podstawie tej zależności zaproponowano metodę oszacowania defoliacji z wykorzystaniem zdjęć lotniczych.The assessment of tree crown defoliation is a useful indicator of the condition and viability of trees. As part of the HESOFF project, an attempt was made to develop a methodology for estimating defoliation of oak tree stands (Quercus robur) using multi-spectral aerial photographs acquired with the six-channel QUERCUS.6 Multisensor Platform. During the vegetation cycle (March- September 2015) aerial imaging of forests at the Krotoszyñska Plate was made (the visible range of electromagnetic radiation and near infrared). In the studied stands, the defoliation level was determined using traditional methods. The Digital Elevation Model (DEM) of the land cover was made on the basis of the photograph and next an unshaded part of the oaks crown was selected. For 49 trees with a known level of defoliation, a PCAanalysis of reflectance was performed taking into account the adequately illuminated part of crowns, the level of defoliation measured in situ and DEM. Analysis showed a strong negative correlation between the level of defoliation and a reflectance determined in optical channel 0.73 µm. On the basis of this relationship, a method for estimating defoliation by means of aerial photographs was proposed

Półautomatyczne pomiary metodą teledetekcji do monitorowania bioenergetycznych upraw Miscanthus spp.

The paper presents the review of the potential application of remote sensing techniques at ground, air, and satellite levels in monitoring, yield assessment for bioenergy crops and the evaluation of natural grass communities of Miscanthus spp. According to the Directive 2009/28, the EC countries are obliged to increase the participation of energy production from renewable energy sources by 20% by 2020. This objective can be achieved in part by using biomass from high energy plantations. Monitoring of Miscanthus growth, one of the most prospective crop species, is important because of its use as bioenergy crop, to evaluate quality and quantity, and for environmental reasons. As Miscanthus is a non-native species in Europe, its uncontrolled spread may threaten the diversity of native species. Contrary to the traditional field-based observations of Miscanthus communities, the remote sensing provide suitable data enable the acquisition of precise data about biomass state and habitat quality. Such methods are highly efficient tools for precise quantitative assessment in agriculture and for the monitoring of natural Miscanthus communities.W pracy przedstawiono przegląd najnowszej literatury dotyczącej możliwości zastosowania technik teledetekcyjnych naziemnych, lotniczych i satelitarnych do monitorowania, prognozowania plonu oraz oceny zbiorowisk naturalnych bioenergetycznych traw należących do Miscanthus spp. Zgodnie z dyrektywą 2009/28 kraje należące do Unii Europejskiej zobowiązane są do 2020 r. do zwiększenia udziału produkcji energii z odnawialnych źródeł o 20%. Cel ten może zostać częściowo osiągnięty przez wykorzystywanie biomasy na cele energetyczne. Monitorowanie wzrostu bioenergetycznej trawy – miskanta, jednego z najbardziej perspektywicznych gatunków roślin uprawnych, jest istotne nie tylko ze względu na jego przeznaczenie jako uprawy bioenergetycznej, ale także ze względów środowiskowych. Ponieważ miskant jest gatunkiem obcym w Europie, jego niekontrolowane rozprzestrzenienie się może zagrozić różnorodności gatunków rodzimych. W przeciwieństwie do tradycyjnych metod obserwacji zbiorowisk miskanta, metody teledetekcyjne dostarczają dokładnych danych o stanie biomasy i jakości zbiorowisk. Metody te są wysoce wydajnymi narzędziami do precyzyjnej oceny ilościowej i jakościowej upraw oraz monitorowania naturalnych zbiorowisk roślinności, m.in. miskanta

Species Diversity of Oak Stands and Its Significance for Drought Resistance

Drought periods have an adverse impact on the condition of oak stands. Research on different types of ecosystems has confirmed a correlation between plant species diversity and the adverse effects of droughts. The purpose of this study was to investigate the changes that occurred in an oak stand (Krotoszyn Plateau, Poland) under the impact of the summer drought in 2015. We used a method based on remote sensing indices from satellite images in order to detect changes in the vegetation in 2014 and 2015. A positive difference was interpreted as an improvement, whereas a negative one was treated as a deterioration of the stand condition. The Shannon-Wiener species diversity was estimated using an iterative principal component analysis (PCA) algorithm based on aerial images. We observed a relationship between the species indices of the individual forest divisions and their response to drought. The highest correlation between the index differences and the Shannon-Wiener indices was found for the Green Normalized Difference Vegetation Index (GNDVI) index (+0.74). In addition, correlations were observed between the mean index difference and the percentage shares in the forest divisions of species such as Pinus sylvestris L. (P. sylvestris) (+0.67 ± 0.08) and Quercus robur L. (Q. robur) (−0.65 ± 0.10). Our results lead us to infer that forest management based on highly diverse habitats is more suitable to meet the challenges in the context of global climatic changes, characterized by increasingly frequent droughts

The impact of drought in 2015 on the health forest condition determined using Landsat-8 OLI images

The main aim of this research was to determine the impact of drought (in 2015) on forests stand condition using remote sensing and statistical techniques. The study was based on the analysis of vegetation indices calculated from a series of Landsat-8 OLI satellite images covering the 2014 and 2015 growing seasons. Various tree biophysical and physical parameters as well as forest habitat characteristics were tested in order to find the most significant factors affecting drought resistance. Three approaches were used: (i) index differences, (ii) PCA analysis, and (iii) ANOVA statistical analysis. All three approaches used in this study indicate that forest biodiversity is the most important factor determining habitat response to stress conditions. Coniferous and mixed tree habitats were less sensitive than deciduous ones. Statistical analysis revealed the relationship between stress and soil types, as those more permeable were less dependent on rainwater. The highest stress was found for precipitation-dependent gley soils. Undergrowth density and height were also indicated as important factors inducing habitat response to a changing weather situation. All the results confirmed the usefulness of mid-infrared based indices for water shortage monitoring in forests. They confirmed that habitat biodiversity has a positive effect on its resistance to stressful conditions. Also forest type (conifer/deciduous) determines it’s sensitivity. Precipitation and groundwater shortages have different effects on the forest condition depending on soil type

Developing an UAV method of monitoring of cyanobacterial blooms in freshwater ecosystems

Cyanobacterial blooms are widespread phenomenon naturally occurring in different types of water bodies. Characteristic indicator of the bloom is a change of water color to blue-green, due to pigments contained by growing cyanobacterial biomass. Recently observed climatic changes and increase of Earth’s surface temperature may lead to intensification and proliferation of cyanobacterial blooms, severe reduction of water quality and changes in functioning of freshwater ecosystems. Monitoring of cyanobacterial blooms appears to be crucial in order to undertake remediation policy, such as biomass harvesting. The aim of our study was to develop an index for cyanobacterial blooms detection with use of unmanned aerial vehicles (UAV). The data was collected from 30 frames floating on the surface of blooming waterbody. First, the reflectances inside the frames were measured by UAV equipped with multispectral camera, then immediately the and phycocyanin concentrations inside frames were measured in situ with use of multiparameter probe. Further statistical analyses allowed to create an index based on Red Edge 740 nm and 717 nm and NIR 842 nm spectral bands. The correlation of the index with phycocyanine concentration measured in situ was estimated as +70%