Estimation of fire severity using pre- and post-fire LiDAR data in sagebrush steppe rangelands

2009 ◽  
Vol 18 (7) ◽  
pp. 848 ◽  
Author(s):  
Cheng Wang ◽  
Nancy F. Glenn
Keyword(s):  
Fire Severity ◽  
Remote Sensing Data ◽  
Biomass Combustion ◽  
Sagebrush Steppe ◽  
Lidar Data ◽  
Vegetation Height ◽  
Severity Estimation ◽  
Before And After ◽  
Forested Areas ◽  
The Difference

Reflectance-based indices derived from remote-sensing data have been widely used for detecting fire severity in forested areas. Rangeland ecosystems, such as sparsely vegetated shrub-steppe, have unique spectral reflectance differences before and after fire events that may not make reflectance-based indices appropriate for fire severity estimation. As an alternative, average vegetation height change ( dh ) derived from pre- and post-fire Light Detection and Ranging (LiDAR) data were used in this study for fire severity estimation. Theoretical deductions were conducted to demonstrate that LiDAR-derived dh is related to biomass combustion and thus can be used for fire severity estimation in rangeland areas. The Jeffreys–Matusita (JM) distance was calculated to evaluate the separability for each pair of fire severity classes, with an average JM distance of 1.14. Thresholds for classifying the level of fire severity were determined according to the mean and standard deviation of each class. A fire-severity classification map with 84% overall accuracy was obtained from the LiDAR dh method. Importantly, this method was sensitive to the difference between the moderate and high fire-severity classes.

Remote Sensing of Forest Fire Severity and Vegetation Recovery

1996 ◽  
Vol 6 (3) ◽  
pp. 125 ◽  
Author(s):  
JD White ◽  
KC Ryan ◽  
CC Key ◽  
SW Running
Keyword(s):  
Satellite Data ◽  
Fire Severity ◽  
Canopy Cover ◽  
Burn Severity ◽  
Vegetation Recovery ◽  
Electromagnetic Spectrum ◽  
Vegetation Types ◽  
Burned Areas ◽  
Before And After ◽  
Forested Areas

Burned forested areas have patterns of varying burn severity as a consequence of various topographic, vegetation, and meteorological factors. These patterns are detected and mapped using satellite data. Other ecological information can be abstracted from satellite data regarding rates of recovery of vegetation foliage and variation of burn severity on different vegetation types. Middle infrared wavelengths are useful for burn severity mapping because the land cover changes associated with burning increase reflectance in this part of the electromagnetic spectrum. Simple stratification of Landsat Thematic Mapper data define varying classes of burn severity because of changes in canopy cover, biomass removal, and soil chemical composition. Reasonable maps of burn severity are produced when the class limits of burn severity reflectance are applied to the entire satellite data. Changes in satellite reflectance over multiple years reveal the dynamics of vegetation and fire severity as low burn areas have lower changes in reflectance relative to high burn areas. This results as a consequence of how much the site was altered due to the burn and how much space is available for vegetation recovery. Analysis of change in reflectance across steppe, riparian, and forested vegetation types indicate that fires potentially increase biomass in steppe areas, while riparian and forested areas are slower to regrow to pre-fire conditions. This satellite-based technology is useful for mapping severely burned areas by exploring the ecological manifestations before and after fire.

scholarly journals Estimación del grado de severidad de incendios en el sur de la provincia de Buenos Aires, Argentina, usando Sentinel-2 y su comparación con Landsat-8

2018 ◽  
pp. 47 ◽  
Author(s):  
J. Delegido ◽  
A. Pezzola ◽  
A. Casella ◽  
C. Winschel ◽  
E. P. Urrego ◽  
...  
Keyword(s):  
Buenos Aires ◽  
Low Cost ◽  
Estimation Error ◽  
Fire Severity ◽  
Inverse Correlation ◽  
Landsat 8 ◽  
Buenos Aires Province ◽  
Before And After ◽  
The Difference ◽  
Sentinel 2

<p>Assessment of rural fire severity is fundamental to evaluate fire damages and to analyze recovery processes in a low-cost and efficient way. Burnt areas covering shrubs and grasslands were estimated in more than 30,000 km<sup>2</sup>  in Argentina from December 2016 to January 2017. The study area presented in this work is located in the South of the Buenos Aires province, and it covers a semiarid area with the presence of xerophilous shrubs and grasslands. This is one of the most abundant ecosystem in Central and Southern Argentina. Field campaigns were carried out over the area affected by the fire in order to georreference the burnt plots and characterized the fire severity in 5 levels. The objective of this work is to analyze the feasibility of new satellites Sentinel-2 for fire studies, as well as provide a comparison to Landsat-8 derived results, because this mission has been one of the most used in it. Pre-fire and postfire Sentinel-2 and Landsat-8 imagery were used to analyze different band combinations to compute a Normalized Difference Spectral Index (NDSI), as well as the difference of this index before and after the fire (dNDSI). Results show a significant correlation (R<sup>2</sup> =0.72 and estimation error of 0.77) between dNDSI derived from Sentinel-2 and the severity levels obtained in the field campaign using bands 8a and 12 (NIR and SWIR), the same bands as used in the Normalized Burn Ratio (NBR). Moreover, results derived from Sentinel-2 are better than results derived from Landsat-8 (R<sup>2</sup> =0.63 and estimation error of 0.92). Furthermore, it is observed that the correlation is improved when Sentinel-2 bands 6 and 5 (located in the Red-Edge region) are considered (R<sup>2</sup> =0.74 and estimation error of 0.76). An inverse correlation has been observed between the recovery of vegetation four months after the fire and the fire severity level.</p>

Using lidar to assess impacts of forest harvest landings on vegetation height by harvest season and the potential for recovery over time

2016 ◽  
Vol 46 (6) ◽  
pp. 869-875 ◽  
Author(s):  
Robert A. Slesak ◽  
Tyler Kaebisch
Keyword(s):  
Soil Compaction ◽  
Positive Relationship ◽  
Tree Regeneration ◽  
Lidar Data ◽  
Forest Harvest ◽  
Vegetation Height ◽  
Time Period ◽  
Wide Range ◽  
The Difference ◽  
Over Time

Tree regeneration and growth is generally reduced at forest harvest landing areas because of significant soil compaction, but it is commonly believed that harvesting in winter can reduce these impacts and that recovery occurs naturally with time. We used lidar data to assess differences in vegetation height between landing and general harvest areas across 79 sites in northern Minnesota, United States, that had been harvested in either summer/fall or winter and between 2 and 175 months since harvest. Vegetation height was significantly lower at landing areas compared with general harvest areas; however, there was no effect of harvest season on the difference (p = 0.50), indicating that impacts occur during all seasons. There was a significant (p < 0.01) positive relationship between the difference in vegetation height and time, regardless the harvest season, providing evidence that recovery occurs across a wide range of conditions within our time period of assessment. Sites with three landings present had the lowest relative landing area and also had the lowest differences in vegetation height between landing and general harvest areas, demonstrating the potential for optimized landing configurations to minimize impacts to growth. Based on our findings, landing areas should be kept as small as reasonably possible during all seasons of harvest, but the need for active reclamation practices is probably not warranted given that recovery occurs within the first few decades after harvest.

scholarly journals UTILIZAÇÃO DO NDVI NA ANÁLISE DA VEGETAÇÃO APÓS OCORRÊNCIA DE INCÊNDIO

Nativa ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 226
Author(s):  
Fabrício Assis Leal ◽  
Cátia Menezes de Souza ◽  
Glória Da Silva Almeida Leal ◽  
Eder Pereira Miguel
Keyword(s):  
Forest Fires ◽  
Fire Severity ◽  
Upper Class ◽  
Chi Square ◽  
Significant Difference ◽  
Before And After ◽  
Chi Square Test ◽  
Biomass Loss ◽  
The Difference ◽  
Very High

O objetivo deste trabalho foi avaliar a vegetação do Parque Nacional das Emas antes e após a ocorrência de fogo, por meio do NDVI. Para a obtenção do NDVI foram utilizadas imagens do satélite ResourceSat-1, em julho/2010 (antes) e setembro/2010 (após). Foram aleatorizados pontos amostrais nas classes mais representativas de vegetação do PARNA, sendo: 60 pontos na classe Campo, 45 pontos na classe Cerrado, 35 pontos na classe Várzea e 35 pontos na classe Mata. Os valores encontrados de NDVI nos pontos amostrados, antes e após a ocorrência do incêndio, foram comparados estatisticamente pelo teste de qui-quadrado (χ²). Para quantificar a perda de biomassa após o incêndio, a imagem NDVI antes do incêndio foi subtraída da imagem NDVI após o incêndio, gerando assim uma imagem da diferença. Esta imagem foi classificada em cinco classes: baixa, moderada, média, alta e muito alta. Os resultados mostraram que houve diferença significativa nos valores de NDVI antes e após o incêndio, para todas as tipologias. Em relação a perda de biomassa, a classe Alta foi a mais representativa entre todas mapeadas, representando 41,1%, seguida pela classe Média (40,6%) e a classe mais extrema Muito Alta com 7,4%. O incêndio afetou, significativamente, as tipologias do parque.Palavras-chave: savana, incêndios florestais, severidade de incêndio, unidade de conservação. APPLICATION OF NDVI IN VEGETATION ANALYSIS AFTER FIRE OCCURRENCE ABSTRACT: The objective of this work was to evaluate the vegetation of Emas' PARNA before and after the occurrence of fire, through NDVI. In order to obtain the NDVI, we used images from the ResourceSat-1 satellite, in July/2010 (before) and September/2010 (after). Sampling points in the most representative PARNA vegetation classes were randomized: 60 points in the Campo class, 45 points in the Cerrado class, 35 points in the Várzea class and 35 points in the Mata class. The NDVI values found in the sampled sites, before and after the occurrence of the fire, were compared statistically by the chi-square test (χ²). To quantify biomass loss after fire, the NDVI image before the fire was subtracted from the NDVI image after the fire, thus generating an image of the difference. This image was classified into five classes: low, moderate, medium, high and very high. The results showed that there was a significant difference in the NDVI values before and after the fire, for all types. In relation to the loss of biomass, the Upper class was the most representative among all mapped, representing 41.1%, followed by the middle class (40.6%) and the most extreme class Very High with 7.4%.Keywords: savannah, forest fires, fire severity, conservation unit.

Tem analysis of multiple-energy arsenic implanted and Rta'd silicon

1987 ◽  
Vol 45 ◽  
pp. 246-247
Author(s):  
R.A. Herring
Keyword(s):  
Device Fabrication ◽  
High Concentration ◽  
Tem Analysis ◽  
Defect Clusters ◽  
High Fluences ◽  
Small Defect ◽  
Before And After ◽  
The Matrix ◽  
The Difference ◽  
Factor Type

Rapid thermal annealing (RTA) of ion-implanted Si is important for device fabrication. The defect structures of 2.5, 4.0, and 6.0 MeV As-implanted silicon irradiated to fluences of 2E14, 4E14, and 6E14, respectively, have been analyzed by electron diffraction both before and after RTA at 1100°C for 10 seconds. At such high fluences and energies the implanted As ions change the Si from crystalline to amorphous. Three distinct amorphous regions emerge due to the three implantation energies used (Fig. 1). The amorphous regions are separated from each other by crystalline Si (marked L1, L2, and L3 in Fig. 1) which contains a high concentration of small defect clusters. The small defect clusters were similar to what had been determined earlier as being amorphous zones since their contrast was principally of the structure-factor type that arises due to the difference in extinction distance between the matrix and damage regions.

Changes in Platelet Aggregability after Ovariectomy

1979 ◽  
Vol 42 (04) ◽  
pp. 1332-1339 ◽  
Author(s):  
Hiroh Yamazaki ◽  
Takeshi Motomiya ◽  
Minoru Sonoda ◽  
Noboru Miyagawa
Keyword(s):  
Platelet Count ◽  
Platelet Activation ◽  
Ovarian Hormones ◽  
Control Group ◽  
Platelet Aggregability ◽  
Appearance Rate ◽  
Before And After ◽  
The Difference ◽  
Induced Aggregation ◽  
Observation Period

SummaryChanges in platelets in 48 patients with uterine myoma before and after hysterectomy with and without ovariectomy were examined. Bilateral ovariectomy in 25 cases (ovariec-tomized group) and unilateral or non-ovariectomy in 23 cases (control group) were performed at the hysterectomy. Platelet count and an appearance rate of secondary aggregation decreased at one day after and increased at one week after the operation, similarly in both the ovariectomized and the control group. The appearance rate of secondary aggregation was reflected in an intensity of aggregation at 5 min after the addition of reagent to PRP. At one month after the operation, the appearance rate of secondary aggregation induced by 3 μM ADP showed a statistically significant decrease in comparison with the preoperation value (P <0.05) and the enhancement of 5-min aggregation was still observed in the control group, while ceased in the ovariectomized group. The difference between the two groups was significant (P < 0.05). There was almost no change in the speed and intensity of primary and secondary aggregation during the observation period. No significant differences in collagen-induced aggregation were noted between the two groups. The results suggest that ovarian hormones, mainly estrogen, facilitate platelet activation which is mediated by the so-called secondary aggregation.

PENGARUH TERAPI TERTAWA TERHADAP PENURUNAN TEKANAN DARAH LANSIA DI UPT PANTI WREDHA BUDHI DHARMA YOGYAKARTA

2019 ◽  
Vol 13 (1) ◽  
Author(s):  
Niken Setyaningrum ◽  
Andri Setyorini ◽  
Fachruddin Tri Fitrianta
Keyword(s):  
Blood Pressure ◽  
Data Analysis ◽  
The Elderly ◽  
Control Group ◽  
Group Comparison ◽  
Control Blood Pressure ◽  
Men And Women ◽  
Treatment Of Hypertension ◽  
Before And After ◽  
The Difference

ABSTRACTBackground: Hypertension is one of the most common diseases, because this disease is suffered byboth men and women, as well as adults and young people. Treatment of hypertension does not onlyrely on medications from the doctor or regulate diet alone, but it is also important to make our bodyalways relaxed. Laughter can help to control blood pressure by reducing endocrine stress andcreating a relaxed condition to deal with relaxation.Objective: The general objective of the study was to determine the effect of laughter therapy ondecreasing elderly blood pressure in UPT Panti Wredha Budhi Dharma Yogyakarta.Methods: The design used in this study is a pre-experimental design study with one group pre-posttestresearch design where there is no control group (comparison). The population in this study wereelderly aged over> 60 years at 55 UPT Panti Wredha Budhi Dharma Yogyakarta. The method oftaking in this study uses total sampling. The sample in this study were 55 elderly. Data analysis wasused to determine the difference in blood pressure before and after laughing therapy with a ratio datascale that was using Pairs T-TestResult: There is an effect of laughing therapy on blood pressure in the elderly at UPT Panti WredhaBudhi Dharma Yogyakarta marked with a significant value of 0.000 (P <0.05)

Klein with Lacan: A Study on the Reception of Lacanian Ideas in Uruguay and Its Effects on Clinical Practices (1955–82)

2020 ◽  
Vol 22 (3) ◽  
pp. 341-361
Author(s):  
Gonzalo Grau-Pérez ◽  
J. Guillermo Milán
Keyword(s):  
Clinical Practice ◽  
Clinical Material ◽  
Clinical Practices ◽  
Before And After ◽  
The Difference ◽  
The 1960S ◽  
The Relationship ◽  
Discursive Approach ◽  
The Way ◽  
Clinical Cases

In Uruguay, Lacanian ideas arrived in the 1960s, into a context of Kleinian hegemony. Adopting a discursive approach, this study researched the initial reception of these ideas and its effects on clinical practices. We gathered a corpus of discursive data from clinical cases and theoretical-doctrinal articles (from the 1960s, 1970s and 1980s). In order to examine the effects of Lacanian ideas, we analysed the difference in the way of interpreting the clinical material before and after Lacan's reception. The results of this research illuminate some epistemological problems of psychoanalysis, especially the relationship between theory and clinical practice.

FRACTIONAL DETERMINATIONS OF URINARY 17-KETOSTEROIDS IN HYPEREMESIS GRAVIDARUM

1962 ◽  
Vol 41 (1) ◽  
pp. 123-128 ◽  
Author(s):  
Pentti A. Järvinen ◽  
Sykkö Pesonen ◽  
Pirkko Väänänen
Keyword(s):  
Hyperemesis Gravidarum ◽  
First Trimester ◽  
Control Group ◽  
Before And After ◽  
Daily Urine ◽  
First Trimester Of Pregnancy ◽  
The Difference

ABSTRACT The fractional determination of 17-ketosteroids in the daily urine was performed in nine cases of hyperemesis gravidarum and in four control cases, in the first trimester of pregnancy both before and after corticotrophin administration. The excretion of total 17-KS is similar in the two groups. Only in the hyperemesis group does the excretion of total 17-KS increase significantly after corticotrophin administration. The fractional determination reveals no difference between the two groups of patients with regard to the values of the fractions U (unidentified 17-KS), A (androsterone) and Rest (11-oxygenated 17-KS). The excretion of dehydroepiandrosterone is significantly higher in the hyperemesis group than in the control group. The excretion of androstanolone seems to be lower in the hyperemesis group than in the control group, but the difference is not statistically significant. The differences in the correlation between dehydroepiandrosterone and androstanolone in the two groups is significant. The high excretion of dehydroepiandrosterone and low excretion of androstanolone in cases of hyperemesis gravidarum is a sign of adrenal dysfunction.

Automatic Tread Gaging Machine

1979 ◽  
Vol 7 (1) ◽  
pp. 31-39
Author(s):  
G. S. Ludwig ◽  
F. C. Brenner
Keyword(s):  
Experimental Tests ◽  
Automatic Machine ◽  
Wear Rates ◽  
Handling Device ◽  
Straight Line ◽  
Component Systems ◽  
Before And After ◽  
Good Repeatability ◽  
The Difference ◽  
Straight Lines

Abstract An automatic tread gaging machine has been developed. It consists of three component systems: (1) a laser gaging head, (2) a tire handling device, and (3) a computer that controls the movement of the tire handling machine, processes the data, and computes the least-squares straight line from which a wear rate may be estimated. Experimental tests show that the machine has good repeatability. In comparisons with measurements obtained by a hand gage, the automatic machine gives smaller average groove depths. The difference before and after a period of wear for both methods of measurement are the same. Wear rates estimated from the slopes of straight lines fitted to both sets of data are not significantly different.

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