Background and Purpose: The main goal of this paper was to highlight the importance of colour infrared (CIR) aerial photographs for efficient inventory, monitoring and predicting the health status of ...forests in changed site conditions. CIR aerial photographs from two aerial surveys conducted in 1989 and 2008 were used to identify and analyze the damage in lowland pedunculated oak (Quercus robur L.) forests during each period, as well as to obtain a dieback trend in the observed period.
Material and Methods: The research was conducted in lowland pedunculated oak forests of Josip Kozarac management unit. CIR aerial photographs (1989) of the research area were taken with a classical camera, while aerial images in 2008 were taken with a digital camera and then converted from digital to analogue form (contact copy - photograph) in order to perform photointerpretation with a SOKKIA MS27 Carl ZEISS Jena mirror stereoscope, magnified by 8x. The health status of particular trees (crowns) was assessed by means of photointerpretation keys in a stereomodel over a systematic 100x100 m sample grid on both 1989 and 2008 aerial photographs. The degree of damage of 4 individual trees was assessed at every grid point in the surveying strips covering the surveyed area. Damage indicators were calculated and thematic maps were constructed on the basis of the interpretation of data for all the grid points.
Results: For the research area a damage index (IO) of 68.36% for oak was determined by photointerpreting individual trees (2008); in other words, this percentage of pedunculate oak trees in the surveyed area was found to be in the damage degree of 2.1 and more. Of 68.36% trees classified in the damage degree of 2.1 or more, mean damage (SO1) amounted to 52.16% and could be classified in the damage degree of 2.2. In 1989, the mean damage index (IO) for pedunculate oak was 48.00%, and pedunculate oak trees with mean damage degree of 2.1 or more (SO1) amounted to 36.03%. The comparison of photointerpretation results from 1989 and 2008 shows that the damage index (IO) for pedunculate oak increased by more than 20%, whereas mean damage (SO) rose by almost 15%. An increase of more than 15% in mean damage of considerably damaged pedunculate oak trees can also be observed.
Conclusions: The obtained results provide not only the current forest condition but also indicate the condition in the field and the purposefulness of aerial surveying, since aerial photographs allow an insight into the condition in the field in a short time period. This in turn enables the efficient application of measures to mitigate the consequences of dieback.
One of the priorities in sustainable forest management is monitoring the health status of trees and stands. From the aspect of remote sensing (RS), the best way of doing this is by interpreting color ...infrared (CIR) aerial photographs; however, this raises the issue of sample size. For this reason, to apply this method in practice, it is indispensable to determine an appropriate sample size to ensure sufficient reliability of the health status assessment of trees in CIR aerial photographs. This research was conducted in lowland forests of pedunculate oak in Croatia. To determine damage in the photographs of the main tree species, a systematic sample with varying dot grid densities—100 × 100 m, 200 × 200 m, 300 × 300 m, 500 × 500 m, 1000 × 1000 m—was used with combinations of different numbers of interpreted trees per sample. Damage indicators were also calculated based on tree distributions obtained by interpreting four trees, two trees and one tree in different sample sizes. The results of the testing showed that there were no statistically significant differences between different sample densities and numbers of interpreted trees in relation to mean damage assessment. Regardless of the fact that there were no statistically significant differences during damage assessment, it was found that by lowering sample densities, starting with 200 × 200 m, the number of trees and the number of sample points per particular sub-compartment significantly decreased, and so did the desired accuracy. Consequently, the participation (distribution) of particular species and damage degrees in the sample were lost, which significantly affected the overall tree health assessment. In contrast, grid densities of 100 × 100 m with one interpreted tree at the raster point proved to be the optimal sample size. This confirms the fact found in earlier research, that is, that the selected sample should have several spatially well-distributed points with a smaller number of trees in the point, and samples with larger numbers of trees in a smaller number of points should be avoided.
Urban Heat Island (UHI) is a phenomenon specific to urban areas where higher air temperatures manifest in the city area in relation to its surrounding rural landscape. Currently, UHI is one of the ...most dangerous environmental conditions for cities as well as their residents. It is expected that the intensity of UHI will increase with climate change. This work presents an analysis of the UHI phenomenon for the City of Zagreb, Croatia in the summertime period 2013–2022. In order to explore UHI, Land Surface Temperature (LST) was calculated using Landsat 8 (OLI TIRS sensor) satellite imagery. After the delineation of UHI, calculated temperatures were put in relation to NDVI (Normalised Difference Vegetation Index) and NDBI (Normalised Difference Built-Up Index) indices for the study area. Results show the similarity of mean temperatures over the observed period. However, the influence of external variables on UHI’s spatial expression was observed. Forest-covered areas and other green parts of the city’s infrastructure express the lowest temperatures, while built-up sites are the hottest points in cities. Results confirm the importance of urban green infrastructure for resilient cities and present the results of a long-term UHI observation in a Southeast European city.
Insulin receptor (Insr) protein is present at higher levels in pancreatic β-cells than in most other tissues, but the consequences of β-cell insulin resistance remain enigmatic. Here, we use an Ins1
...knock-in allele to delete Insr specifically in β-cells of both female and male mice. We compare experimental mice to Ins1
-containing littermate controls at multiple ages and on multiple diets. RNA-seq of purified recombined β-cells reveals transcriptomic consequences of Insr loss, which differ between female and male mice. Action potential and calcium oscillation frequencies are increased in Insr knockout β-cells from female, but not male mice, whereas only male βInsr
islets have reduced ATP-coupled oxygen consumption rate and reduced expression of genes involved in ATP synthesis. Female βInsr
and βInsr
mice exhibit elevated insulin release in ex vivo perifusion experiments, during hyperglycemic clamps, and following i.p. glucose challenge. Deletion of Insr does not alter β-cell area up to 9 months of age, nor does it impair hyperglycemia-induced proliferation. Based on our data, we adapt a mathematical model to include β-cell insulin resistance, which predicts that β-cell Insr knockout improves glucose tolerance depending on the degree of whole-body insulin resistance. Indeed, glucose tolerance is significantly improved in female βInsr
and βInsr
mice compared to controls at 9, 21 and 39 weeks, and also in insulin-sensitive 4-week old males. We observe no improved glucose tolerance in older male mice or in high fat diet-fed mice, corroborating the prediction that global insulin resistance obscures the effects of β-cell specific insulin resistance. The propensity for hyperinsulinemia is associated with mildly reduced fasting glucose and increased body weight. We further validate our main in vivo findings using an Ins1-CreERT transgenic line and find that male mice have improved glucose tolerance 4 weeks after tamoxifen-mediated Insr deletion. Collectively, our data show that β-cell insulin resistance in the form of reduced β-cell Insr contributes to hyperinsulinemia in the context of glucose stimulation, thereby improving glucose homeostasis in otherwise insulin sensitive sex, dietary and age contexts.
Negativne posljedice propadanja šuma nastoje se umanjiti provođenjem gospodarskih mjera i praćenjem zdravstvenog stanja stabala, odnosno procjenom oštećenosti krošanja. Utvrđivanje zdravstvenog ...stanja šuma provodi se, osim terestričkim načinom, i metodama daljinskih istraživanja – interpretacijom infracrvenih kolornih (ICK) aerosnimaka.
Inventarizacija oštećenosti šuma pomoću aerosnimaka temelji se na ustanovljavanju stupnja oštećenosti pojedinačnih stabala (krošanja), uz kvalitetno izrađen fotointerpretacijski ključ. Na temelju provedene fotointerpretacije infracrvenih kolornih (ICK) aerosnimaka, mogu se odrediti pouzdani statistički podaci o oštećenosti šuma. Inventarizacije oštećenosti šuma na ICK aerosnimkama do sada su se provodile fotointerpretacijom analognih aerosnimaka na analitičkim stereoinstrumentima. Napretkom tehnologije analogne snimke su zamijenjene digitalnim, analitički stereoinstrumenti - digitalnim fotogrametrijskim stanicama, a interpretacija se obavlja u programu na zaslonu računala.
Osnovni cilj istraživanja bio je usporediti rezultate procjene oštećenosti krošanja na analognim i digitalnim ICK aerosnimkama istoga područja, zbog čega je bilo potrebno aerosnimke iz 1989. godine skeniranjem prevesti u digitalni oblik, te digitalne snimke iz 2008. godine prevesti u analogni oblik.
Za dio gospodarskih jedinica Josip Kozarac i Opeke, provedena je interpretacija analognih i digitalnih aerosnimaka iz dva perioda snimanja (1989. i 2008. godina). Na svakoj točki rastera 100x100 m procijenjena su 4 najbliža stabla (krošnje) te izračunati pokazatelji oštećenosti (O, SO, IO, SO1) za pojedine vrste drveća, za sve interpretirane vrste zajedno, po prugama snimanja, te ukupno za područje istraživanja.
Na temelju izračunatih pokazatelja oštećenosti, dobivenih interpretacijom analognih i digitalnih snimaka iz 1989., te 2008. godine, utvrđeno je da između rezultata ne postoji značajna razlika s obzirom na procjenu zdravstvenog stanja stabala (oštećenosti krošanja).
Time su poboljšane postojeće metode procjene zdravstvenoga stanja i ukazano na mogućnosti primjene digitalnih ICK aerosnimaka u šumarstvu.
Efforts to mitigate negative consequences of massive forest dieback include the implementation of economic measures, monitoring the health status of individual trees i.e. assessment of crown damage. Apart from terrestrial methods, forest health is also determined with remote sensing methods, which involve interpretation of color infrared (CIR) aerial photographs.
The inventory of forest damage by using aerial photography is based on the establishment of the degree of damage to individual trees (crowns) using a well-designed photo interpretation key. Reliable statistical data of forest damage can be obtained on the basis of photo interpretation of CIR aerial photography.
Inventories of forest damage have so far been conducted with photo interpretation of analog aerial photographs on analytical stereo instruments. With the advancement of technology, analog images have been replaced by digital and analytical stereo instruments – by digital photogrammetric workstations, and interpretation is done on the computer screen.
The main goal of the research was to compare the results of crown damage assessment on analog and digital ICK aerial photographs of the same area, which is why it was necessary to convert aerial photographs from 1989 by scanning into digital form, and convert digital images from 2008 into analog form.
Analog and digital aerial photographs from two recording periods (1989 and 2008) were interpreted for a part of the management units Josip Kozarac and Opeke. At each point of a 100x100 m grid, 4 nearest trees (crowns) were estimated and damage indicators (damage-O, mean damage-SO, damage index-IO, mean damage1-SO1) were calculated for individual tree species, for all the interpreted species together, per surveying strips, and for the total research area.
On the basis of calculated damage indicators obtained by interpreting analog and digital images from 1989 and 2008, it was found that there was no statistically significant difference between the results in terms of tree health assessment.
The conducted research improved the existing methods of assessing the health status of individual trees and stands, and pointed out the possibilities of applying digital CIR aerial photographs in forestry.
Background and Purpose: In Zagreb, the forests have assumed the characteristics of forest parks, of which the most famous and the most visited is Maksimir Park. The health condition of many trees has ...deteriorated due to environmental changes and the forest’s age. The tree health status can be monitored by direct observation in the field using the terrestrial method, or by remote sensing methods. Recent advances in technology have made it possible to use high-resolution satellite imagery to monitor the damage.
Materials and Methods: In order to estimate the health status of trees, the research area - Maksimir Forest Park - was visually interpreted by means of the WorldView 2 (WV2) satellite image, color composite (8, 5, 3). Such color composite was also used to delineate the strata. After delineation, a systematic sample of 25x25 m was laid over the stratum to help interpret the tree health status. Differences in tree damage were observed by comparing the WV2 images and other satellite images (Google Earth images from 2014 and 2016) recorded at different points in time. Field research was then conducted in order to inventory the current situation.
Results: The main results of the research in Maksimir Forest Park include the calculation of damage indicators by tree species, as well as thematic maps with the spatial distribution of the mean damage (SO) and damage index (IO) for those tree species which are most represented in a particular stratum. Mean and significant damage of the most represented tree species and overall is also presented spatially in the form of thematic maps. A comparison of the results of WV2 satellite imagery and satellite images taken from Google Earth denoted a change in the tree health status, which confirms that satellite imagery can serve to inventory and track the condition in an area over a number of years. Field investigations and the assessment of tree health status confirmed the results obtained by satellite imagery interpretation.
Conclusions: Since quality forest monitoring is based on systematic collection of forest data in any area or at any point in time, the obtained results not only represent the current health status, but also provide a basis for monitoring and predicting the future conditions.
Silver fir is one of the most important commercial and ecological species in Croatia, and is currently the most damaged tree species in Croatian forests. It is increasingly being infested by white ...mistletoe, whose irrational consumption of water and nutrients contributes to physiological weakening of the tree. Mistletoe may indicate the presence of stress factors in the site and may even cause premature death. The increment of mistletoe-infested trees is lower compared to that of non-infested trees. Hence, these trees should have a cutting priority, while their timber still retains its commercial value. Areas of mistletoe-infested fir forests are expanding; therefore, there is a high correlation between silver fir forest damage and mistletoe distribution, with an almost exponential increase in mistletoe populations. The purpose of this research was to develop an efficient and reliable method of mistletoe detection. Surveying was performed in the mountain area of beech-fir forests, using a hyperspectral scanner. The Spectral Angle Mapper (SAM) classification for 5° proved to be the best classification method. The results were also confirmed by terrestrial validation, i.e. aerial surveying with a non-pilot aircraft from a height of ~30 m above the crowns. The results of this research do not differ significantly from the results obtained with standard ground methods. Limitations of standard ground methods further highlight the importance and efficiency of hyperspectral imagery in mistletoe detection. Furthermore, the first “spectral signatures” - endmembers for fir and mistletoe, were determined, and entered into a spectral library database. The results of this research are applicable primarily in the field of forest management, protection and harvesting, but they can also supply experts in other fields with a basis for explaining various observed phenomena. It outlines some of the possibilities of the application both in scientific and operative fields.
Svi objekti reflektiraju, apsorbiraju ili emitiraju elektromagnetsko zračenje ovisno o sastavu, stvarajući jedinstvene uzorke koje zovemo spektralni potpisi ili endmemberi. Čisti spektralni uzorci ...definiraju se u idealnim terenskim ili laboratorijskim uvjetima, gdje je spektar refleksije dobiven uporabom spektroradiometra fokusiranog na jednu površinu. Prema istraživanjima, većina spektralno čistih uzoraka odnosi se na istraživanja minerala. Spektralni potpisi vegetacije, za razliku od spektralnih potpisa minerala, su dinamični (u spektralnoj, prostornoj i vremenskoj rezoluciji), znatno zahtjevniji za prikupljanje i dokumentiranje, te ih treba s oprezom ugraditi u spektralne knjižnice. Postoji nekoliko spektralnih knjžnica (većih i manjih) koje su organizirane po poglavljima, a sastoje se od uzoraka koji imaju dovoljan broj analiza i dokumentaciju za utvrđivanje kvalitete spektra. U ovome istraživanju izdvojeni su spektralni potpisi za nekoliko vrsta u Hrvatskoj: hrast lužnjak (
Quercus robur
L.), običnu bukvu (
Fagus sylvatica
L.), običnu jelu (
Abies alba
Mill.), običnu smreku (
Picea abies
L.), bijelu imelu (
Viscum album
L.
ssp. Abietis
(Weisb.)) i žutu imelu (
Loranthus europaeus
Jacq
.
). Svrha istraživanja je bila uspostaviti spektralnu knjižnicu za buduća istraživanja primjene hiperspektralnih skenera pri detekciji vrsta drveća.
Za prikupljanje spektralnih potpisa korišten je hiperspektralni linijski skener ImSpector V9, koji snima vidljivi i bliži infracrveni dio spektra od 430 do 900 nm. Osim njega korišten je i senzor sunčevog zračenja FODIS, kako bi dobili prosječnu vrijednost sunčeve insolacije u trenutku snimanja. Snimanje je provedeno u kontroliranim uvjetima. Uzorci su postavljeni na kružnu podlogu sa naznačenom podjelom za svakih 45 stupnjeva točno u centru optičke osi skenera, te su rotirani kružno. Spektralne snimke su zatim obrađivane u softveru ImageJ gdje su izdvojeni podaci za daljnju analizu.
Nakon obračuna srednjih vrijednosti po vrstama napravljene su usporedbe između vrsta. Dobiveni rezultati pokazali su preklapanja u vidljivom dijelu spektra, dok u bližem infracrvenom dijelu spektra vrste diferenciraju jedna od druge, odnosno rezultati pokazuju kako postoji razlika između spektralnih krivulja uzoraka.
Provedenim istraživanjem definirani su postupci uzimanja uzoraka i dobiveni spektralni potpisi za istraživane vrste (endmemberi). Spektralni potpisi postali su dio spektralne knjižnice, a najznačajniji rezultat istraživanja je mogućnost primjene za detekciju vrsta na hiperspektralnim snimkama.
All objects reflect, absorb or emit electromagnetic radiation depending on the composition, creating unique patterns called spectral signatures or endemembers. Pure spectral samples are defined in ideal field or laboratory conditions, where the spectrum of reflection is obtained using a spectroradiometer focused on one surface. According to researches, most spectral-pure samples refer to mineral exploration. Spectral signatures of vegetation, unlike minerals, are dynamic (in spectral, spatial and temporal resolution), considerably demanding for collecting and documenting, and need to be incorporated with caution in spectral libraries. There are several spectral libraries (bigger and smaller) that are organized by chapters which consist of samples that are adequately reviewed and documented to determine the spectrum quality. In this study, the spectral signatures for several species in Croatia were isolated: Oak (
Quercus robur
L.), Common Beech (
Fagus sylvatica
L.), Silver fir (
Abies alba
Mill.), Norway spruce (
Picea abies
L.), White-berried mistletoe (
Viscum album
L.
ssp. Abietis
(Weisb.)) and Yellow Mistletoe (
Loranthus europaeus
Jacq.). The purpose of the research was to establish a spectral library for future research into hyperspectral scanners for tree species detection.
For collecting spectral signatures, the hyperspectral line scanner ImSpector V9 was used to capture the visible and near infrared spectrum (430-900 nm). In addition, the FODIS solar radiation sensor was used to obtain the average value of the solar insolation at the time of recording. Recording was performed under controlled conditions. Samples were placed on the circular base with the indicated division for every 45 degrees exactly in the center of the optical axis of the scanner and were rotated circularly. Spectral images were then processed in ImageJ software where data was extracted for further analysis.
After calculation of the mean values by species, comparisons were made between species. The obtained results showed overlaps in the visible part of the spectrum. In the near infrared part of the spectrum they differentiate from one another, apropos the results show that there is a difference between the spectral curves of the samples.
The research carried out defines sampling procedures and obtained spectral signatures for the investigated species. Spectral signatures have become part of the spectral library, and the most significant result of the research is the ability to detect the species on hyperspectral images.
Od samoga početka razvoja daljinskih istraživanja ljudi su pokušavali stvoriti alat za proučavanje Zemljine površine i dinamičnih pojava na njoj. Napretkom tehnologije najprije za vojne, a potom i za ...istraživačke potrebe, razvijeni su senzori za prikupljanje podataka snimanjem elektromagnetskoga spektra (multispektralni i hiperspektralni). U trenutku kada su postali dostupni za uporabu u civilnoj zajednici, postale su očigledne potencijalne koristi uporabe hiperspektralnih podataka. Razvoj hiperspektralnih senzora slijedio je razvoj računalne tehnologije i napredak softvera za obradu velikoga broja prikupljenih podatka.
Danas se hiperspektralni senzori sve više upotrebljavaju za razne namjene: proučavanje ekosustava, atmosfere, klime, hidrologije, iskorištavanja minerala, načina korištenja zemljišta, zemljišnoga pokrova i vegetacije. Zahvaljujući velikomu broju raznovrsnih informacija koje pružaju, hiperspektralni senzori imaju veliku mogućnost primjene u nadzoru i upravljanja okolišem te pomažu unapređenju upravljanja i donošenju boljih odluka pri ranom definiranju problema.
Prva primjena hiperspektralnih senzora u šumarstvu u Hrvatskoj vezana je uz program Europske zajednice iz 2005. godine, kada su provedena prva snimanja linijskim hiperspektralnim senzorom. U sklopu provedenih snimanja izdvojene su prve spektralne krivulje obične jele i bijele imele, na osnovi kojih je prvi put izdvojena vrsta unutar vrste, odnosno pomoću hiperspektralnih snimaka razlučeni su grmovi poluparazitske vrste unutar krošanja domaćina te su definirane procedure za snimanja na velikim površinama.
From the very beginning of the development of remote sensing, humans have been trying to create a tool to study the Earth’s dynamic surface and its phenomena. With the advancement of technology, first for the military and then for research purposes, sensors have been developed to collect data by recording the electromagnetic spectrum (multi and hyperspectral). From the moment they became available for civilian use, the potential benefits of using hyperspectral data became apparent. The development of hyperspectral systems followed the development of computer technologies and the progress of software for processing a large number of collected data.Nowadays, hyperspectral sensors are increasingly being used for various purposes: ecosystem study, atmosphere, climate, hydrology, mineral exploitation, land use, land cover, and vegetation. Thanks to the wide variety of information they provide, hyperspectral sensors have large application potential in environmental monitoring and management. Also, they help to improve management and better decision-making at early problem defining.The first application of hyperspectral sensors in Croatian forestry relates to the European Community program of 2005, when the first imaging with a line hyperspectral scanner was conducted. Within the conducted imaging, the first spectral curves of Silver fir and White berried mistletoe were separated. On the basis of this separation, for the first time, the difference between these two species was established. In other words, hyperspectral imagery was used to distinguish shrubs of semi-parasitic species within the host canopy. Also, procedures for large-area imaging were defined.
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