Metcalfa pruinosa (Say, 1830) introduced into the Czech Republic: (Hemiptera, Flatidae)

A large population of the Nearctic planthopper Metcalfa pruinosa (Say, 1830) (Hemiptera, Flatidae), introduced and acclimatized in South Europe in late 1970's, was found in 2001 in an outdoor ornamental gardening shop in the city of Brno in the Czech Republic, being the first record of the species and the family in the country and its northernmost record in Europe. M. pruinosa, probably introduced in the egg stage on ornamental shrubs from Italy, prefered young twigs of Thuja occidentalis, Juniperus communis and Sorbus aucuparia and was also found in numbers on Lilium spp. The damage on affected plants was rather of an aesthetic kind (spots of waxy filaments on shoots), even though a production of honeydew and a consequent development of sooty moulds was also observed. A brief review of published information on the distribution, biology and economic importance of M. pruinosa is given

Performance of the PROSPECT leaf radiative transfer model version 4 for Norway spruce needles

Leaf optical properties (LOPs) are a key input parameter for vegetation canopy radiative transfer models. The uncertainty introduced in the measurement and/or the simulation of this spectral information determines a final reliability of the modelled canopy reflectance. The broad-leaf radiative transfer model PROSPECT version 3.01 has been previously applied for some needle-leaf type species (e.g. pine trees) to estimate biochemical parameters through its inversion. Nevertheless, in a particular case of Norway spruce (Picea abies (L.) Karst.) PROSPECT 3.01 showed a poor performance in near infrared wavelengths and had to be recalibrated. Therefore, the applicability of PROSPECT version 4, which has been recently released, is verified for this type of leaves in this experiment. Forward simulations of an optimized version of the original PROSPECT 4 suggest that it is possible to reduce the average RMSE of reflectance and transmittance from 8% to 3.5- 4 % in the near infrared domain. For this achievement, the absorption coefficients for chlorophyll and dry matter together with the refractive index had to be simultaneously optimized via model inversion using measured LOPs of Norway spruce needles

Measurement methods and variability assessment of the Norway spruce total leaf area: implications for remote sensing

Estimation of total leaf area (LAT) is important to express biochemical properties in plant ecology and remote sensing studies. A measurement of LAT is easy in broadleaf species, but it remains challenging in coniferous canopies. We proposed a new geometrical model to estimate Norway spruce LAT and compared its accuracy with other five published methods. Further, we assessed variability of the total to projected leaf area conversion factor (CF) within a crown and examined its implications for remotely sensed estimates of leaf chlorophyll content (Cab). We measured morphological and biochemical properties of three most recent needle age classes in three vertical canopy layers of a 30 and 100-year-old spruce stands. Newly introduced geometrical model and the parallelepiped model predicted spruce LAT with an error \u3e5 % of the average needle LAT, whereas two models based on an elliptic approximation of a needle shape underestimated LAT by up to 60 %. The total to projected leaf area conversion factor varied from 2. 5 for shaded to 3. 9 for sun exposed needles and remained invariant with needle age class and forest stand age. Erroneous estimation of an average crown CF by 0. 2 introduced an error of 2-3 μg cm-2 into the crown averaged Cab content. In our study, this error represents 10-15 % of observed crown averaged Cab range (33-53 μg cm-2). Our results demonstrate the importance of accurate LAT estimates for validation of remotely sensed estimates of Cab content in Norway spruce canopies

Measuring solar-induced fluorescence from unmanned aircraft systems for operational use in plant phenotyping and precision farming

Demand for high spatial and temporal resolution measurements has triggered a rapid development of unmanned aircraft systems (UAS) for plant phenotyping and precision farming purposes. Similarly, recent progress in low-altitude remote sensing of solar-induced chlorophyll fluorescence (SIF) resulted in several studies aiming at the development of SIF proximal sensing approaches. Although first experimental results are promising, the requirements for reliable and repeatable measurements in agricultural experiments still constrain applicability of these platforms. In this study, we analyze current capabilities and potentials of SIF measuring UAS for operational use. We highlight existing challenges and outline how UAS SIF sensing could be used more frequently and reliably in precision agriculture applications in the near future.Peer reviewe

Contribution to the Auchenorrhyncha fauna of the Pálava Protected Landscape Area (Czech Republic): (Hemiptera: Fulgoromorpha et Cicadomorpha)

Ein Beitrag zur Zikadenfauna des Landschaftsschutzgebiets Pálava (Tschechische Republik). – Es wird eine Liste der Zikadenarten präsentiert, die im Rahmen der Exkursionen zur 17. Mitteleuropäischen Zikadentagung in Mikulov, Süd-Mähren, Tschechische Republik im August 2010 gesammelt wurden. Insgesamt konnten 133 Arten an den 4 Untersuchungsstandorten nachgewiesen werden. Eine Art, Macrosteles spinosus Kwon, 2013, wurde zum ersten Mal in der Tschechischen Republik nachgewiesen, 34 Arten sind neu für die Fauna des Landschaftsschutzgebiets Pálava und das Biosphärenreservat Dolní Morava. Naturschutzfachlich wertvoll ist das Gebiet aufgrund des Vorkommens vieler seltener, stenotoper Zikadenarten, insbesondere von Besiedlern der Trockenrasen, der offenen, trocken-warmen Buschvegetation und der letzten Binnensalzstellen.A list of Auchenorrhyncha species collected from field excursions during the 17th Central-European Auchenorrhyncha Meeting held in Mikulov, South Moravia, Czech Republic in August 2010 is given. A total of 133 species was recorded at four sites. One species, Macrosteles spinosus Kwon, 2013, is recorded for the first time for the Czech Republic and 34 species are new records for the fauna of the Pálava Protected Landscape Area and the Dolní Morava Biosphere Reserve. The area is valuable from a nature conservation viewpoint for the occurrence of many rare stenotopic Auchenorrhyncha species associated particularly with dry grassland vegetation, open xerothermic woodland and remnants of inland saltmarshes

Influence of cosine corrector and UAS platform dynamics on airborne spectral irradiance measurements

Measuring solar-induced chlorophyll fluorescence from small-sized Unmanned Aircraft Systems (UAS) can potentially fill the scaling gap between ground-based and airborne/space-borne observations. These measurements require well calibrated' high-spectral resolution spectroradiometers and precise measurements of vegetation radiance and incoming solar irradiance. Here we present a system equipped with a spectroradiometer with a split optical path that measures incoming irradiance through a cosine corrector/diffuser. The objectives of this study are to characterise cosine corrected solar irradiance measurements with regard to sensor homogeneity and possible offset from an ideal cosine response. We further suggest a methodology to calculate a corrected zenith angle that accounts for changing sensor orientation due to pitch, roll and heading of the UAS platform during flight. We found that the cosine corrector is sufficiently homogeneous, thus measurements are independent of UAS heading. The response follows the cosine law for zenith angles, however, the sensor significantly underestimated irradiance for zenith angles > 10°, with overall cosine errors ranging from 0.991 to 1.229. Yet, typical in-flight platform pitch and roll angles produce a zenith angle offset of up to 6° in low wind conditions. Cosine sensor measurements corrected for the zenith angle offset and the cosine error resulted in a 1.7 % change in irradiance

Relation of chlorophyll fluorescence sensitive reflectance ratios to carbon flux measurements of Montanne grassland and Norway spruce forest ecosystems in the temperate zone

We explored ability of reflectance vegetation indexes (VIs) related to chlorophyll fluorescence emission (R686/R630, R 740/R800) and de-epoxidation state of xanthophyll cycle pigments (PRI, calculated as (R531 - R570) (R 531 - R570)) to track changes in the CO2 assimilation rate and Light Use Efficiency (LUE) in montane grassland and Norway spruce forest ecosystems, both at leaf and also canopy level. VIs were measured at two research plots using a ground-based high spatial/spectral resolution imaging spectroscopy technique. No significant relationship between VIs and leaf light-saturated CO2 assimilation (AMAX) was detected in instantaneous measurements of grassland under steady-state irradiance conditions. Once the temporal dimension and daily irradiance variation were included into the experimental setup, statistically significant changes in VIs related to tested physiological parameters were revealed. ΔPRI and Δ(R686 R630) of grassland plant leaves under dark-to-full sunlight transition in the scale of minutes were significantly related to AMAX (R2 = 0.51). In the daily course, the variation of VIs measured in one-hour intervals correlated well with the variation of Gross Primary Production (GPP), Net Ecosystem Exchange (NEE), and LUE estimated via the eddy-covariance flux tower. Statistical results were weaker in the case of the grassland ecosystem, with the strongest statistical relation of the index R686 R630 with NEE and GPP