scholarly journals A Statistical Model to Detect Asymptomatic Infectious Individuals with an Application in the Phytophthora alni-Induced Alder Decline

2010 ◽  
Vol 100 (11) ◽  
pp. 1262-1269 ◽  
Author(s):  
Chabi Fabrice Elegbede ◽  
Jean-Claude Pierrat ◽  
Jaime Aguayo ◽  
Claude Husson ◽  
Fabien Halkett ◽  
...  
Keyword(s):  
Production Level ◽  
Time Lags ◽  
Individual Tree ◽  
Inoculum Sources ◽  
Inoculum Production ◽  
Dead Trees ◽  
Infection Pressure ◽  
Production Experiment ◽  
Cox's Regression ◽  
Asymptomatic Individuals

In some diseases—in particular, tree root infection—stages of infection and inoculum production level and timing are not readily observable because of uncertainty or time lags in symptom appearance. Here, we pose a criterion, based on relative hazard of disease symptoms, to discriminate between healthy and asymptomatic infected individuals. We design a statistical procedure to estimate the criterion for a 6-year survey of alder decline along a northeastern French river. Individual tree symptom hazard was modeled with Cox's regression model, taking estimation of local infection pressure as a risk factor. From an inoculum production experiment, we thereafter assessed the inoculum production level of target trees, including symptomatic and asymptomatic trees ranked according to their symptoms hazard. Using receiver operating characteristic methods, we first evaluated the criterion performance and determined the discrimination threshold to sort out asymptomatic individuals into healthy and infected. Then, we highlighted the fact that the infected asymptomatic trees were among the major inoculum producers whereas severely declining and dead trees were found to be poor inoculum sources.

scholarly journals Classification of Tree Species as Well as Standing Dead Trees Using Triple Wavelength ALS in a Temperate Forest

2019 ◽  
Vol 11 (22) ◽  
pp. 2614 ◽  
Author(s):  
Nina Amiri ◽  
Peter Krzystek ◽  
Marco Heurich ◽  
Andrew Skidmore
Keyword(s):  
Tree Species ◽  
Feature Selection Method ◽  
Silver Fir ◽  
Maximum Point ◽  
Individual Tree ◽  
Dead Trees ◽  
Multi Wavelength ◽  
Standing Dead ◽  
Standing Dead Trees ◽  
532 Nm

Knowledge about forest structures, particularly of deadwood, is fundamental for understanding, protecting, and conserving forest biodiversity. While individual tree-based approaches using single wavelength airborne laserscanning (ALS) can successfully distinguish broadleaf and coniferous trees, they still perform multiple tree species classifications with limited accuracy. Moreover, the mapping of standing dead trees is becoming increasingly important for damage calculation after pest infestation or biodiversity assessment. Recent advances in sensor technology have led to the development of new ALS systems that provide up to three different wavelengths. In this study, we present a novel method which classifies three tree species (Norway spruce, European beech, Silver fir), and dead spruce trees with crowns using full waveform ALS data acquired from three different sensors (wavelengths 532 nm, 1064 nm, 1550 nm). The ALS data were acquired in the Bavarian Forest National Park (Germany) under leaf-on conditions with a maximum point density of 200 points/m 2 . To avoid overfitting of the classifier and to find the most prominent features, we embed a forward feature selection method. We tested our classification procedure using 20 sample plots with 586 measured reference trees. Using single wavelength datasets, the highest accuracy achieved was 74% (wavelength = 1064 nm), followed by 69% (wavelength = 1550 nm) and 65% (wavelength = 532 nm). An improvement of 8–17% over single wavelength datasets was achieved when the multi wavelength data were used. Overall, the contribution of the waveform-based features to the classification accuracy was higher than that of the geometric features by approximately 10%. Our results show that the features derived from a multi wavelength ALS point cloud significantly improve the detailed mapping of tree species and standing dead trees.

scholarly journals Remotely Sensed Single Tree Data Enable the Determination of Habitat Thresholds for the Three-Toed Woodpecker (Picoides tridactylus)

2018 ◽  
Vol 10 (12) ◽  
pp. 1972 ◽  
Author(s):  
Katarzyna Zielewska-Büttner ◽  
Marco Heurich ◽  
Jörg Müller ◽  
Veronika Braunisch
Keyword(s):  
Bark Beetles ◽  
Laser Scanning ◽  
Positive Relationship ◽  
Spatial Scales ◽  
Keystone Species ◽  
Remote Sensing Data ◽  
Individual Tree ◽  
Substrate Quality ◽  
Dead Trees ◽  
Negative Effect

Forest biodiversity conservation requires precise, area-wide information on the abundance and distribution of key habitat structures at multiple spatial scales. We combined airborne laser scanning (ALS) data with color-infrared (CIR) aerial imagery for identifying individual tree characteristics and quantifying multi-scale habitat requirements using the example of the three-toed woodpecker (Picoides tridactylus) (TTW) in the Bavarian Forest National Park (Germany). This bird, a keystone species of boreal and mountainous forests, is highly reliant on bark beetles dwelling in dead or dying trees. While previous studies showed a positive relationship between the TTW presence and the amount of deadwood as a limiting resource, we hypothesized a unimodal response with a negative effect of very high deadwood amounts and tested for effects of substrate quality. Based on 104 woodpecker presence or absence locations, habitat selection was modelled at four spatial scales reflecting different woodpecker home range sizes. The abundance of standing dead trees was the most important predictor, with an increase in the probability of TTW occurrence up to a threshold of 44–50 dead trees per hectare, followed by a decrease in the probability of occurrence. A positive relationship with the deadwood crown size indicated the importance of fresh deadwood. Remote sensing data allowed both an area-wide prediction of species occurrence and the derivation of ecological threshold values for deadwood quality and quantity for more informed conservation management.

scholarly journals CLASSIFICATION OF TREE SPECIES AND STANDING DEAD TREES BY FUSING UAV-BASED LIDAR DATA AND MULTISPECTRAL IMAGERY IN THE 3D DEEP NEURAL NETWORK POINTNET++

2020 ◽  
Vol V-2-2020 ◽  
pp. 203-210
Author(s):  
S. Briechle ◽  
P. Krzystek ◽  
G. Vosselman
Keyword(s):  
Neural Network ◽  
Tree Species ◽  
Deep Neural Network ◽  
Lidar Data ◽  
Individual Tree ◽  
Dead Trees ◽  
Standing Dead ◽  
Standing Dead Trees ◽  
Multiple Tree

Abstract. Knowledge of tree species mapping and of dead wood in particular is fundamental to managing our forests. Although individual tree-based approaches using lidar can successfully distinguish between deciduous and coniferous trees, the classification of multiple tree species is still limited in accuracy. Moreover, the combined mapping of standing dead trees after pest infestation is becoming increasingly important. New deep learning methods outperform baseline machine learning approaches and promise a significant accuracy gain for tree mapping. In this study, we performed a classification of multiple tree species (pine, birch, alder) and standing dead trees with crowns using the 3D deep neural network (DNN) PointNet++ along with UAV-based lidar data and multispectral (MS) imagery. Aside from 3D geometry, we also integrated laser echo pulse width values and MS features into the classification process. In a preprocessing step, we generated the 3D segments of single trees using a 3D detection method. Our approach achieved an overall accuracy (OA) of 90.2% and was clearly superior to a baseline method using a random forest classifier and handcrafted features (OA = 85.3%). All in all, we demonstrate that the performance of the 3D DNN is highly promising for the classification of multiple tree species and standing dead trees in practice.

scholarly journals UAV Laser Scans Allow Detection of Morphological Changes in Tree Canopy

2020 ◽  
Vol 12 (22) ◽  
pp. 3829
Author(s):  
Martin Slavík ◽  
Karel Kuželka ◽  
Roman Modlinger ◽  
Ivana Tomášková ◽  
Peter Surový
Keyword(s):  
Point Cloud ◽  
Laser Scanning ◽  
Morphological Changes ◽  
Tree Canopy ◽  
High Temporal Resolution ◽  
Human Observer ◽  
Individual Tree ◽  
Dead Trees ◽  
Multi Temporal ◽  
Cloud Metrics

High-resolution laser scans from unmanned aerial vehicles (UAV) provide a highly detailed description of tree structure at the level of fine branches. Apart from ultrahigh spatial resolution, unmanned aerial laser scanning (ULS) can also provide high temporal resolution due to its operability and flexibility during data acquisition. We examined the phenomenon of bending branches of dead trees during one year from ULS multi-temporal data. In a multi-temporal series of three ULS datasets, we detected a synchronized reversible change in the inclination angles of the branches of 43 dead trees in a stand of blue spruce (Picea pungens Engelm.). The observed phenomenon has important consequences for both tree physiology and forest remote sensing (RS). First, the inclination angle of branches plays a crucial role in solar radiation interception and thus influences the total photosynthetic gain. The ability of a tree to change the branch position has important ecophysiological consequences, including better competitiveness across the site. Branch shifting in dead trees could be regarded as evidence of functional mycorrhizal interconnections via roots between live and dead trees. Second, we show that the detected movement results in a significant change in several point cloud metrics often utilized for deriving forest inventory parameters, both in the area-based approach (ABA) and individual tree detection approaches, which can affect the prediction of forest variables. To help quantify its impact, we used point cloud metrics of automatically segmented individual trees to build a generalized linear model to classify trees with and without the observed morphological changes. The model was applied to a validation set and correctly identified 86% of trees that displayed branch movement, as recorded by a human observer. The ULS allows for the study of this phenomenon across large areas, not only at individual tree levels.

Spread of Armillariaostoyae in juvenile lodgepole pine stands in west central Alberta

1991 ◽  
Vol 21 (1) ◽  
pp. 20-24 ◽  
Author(s):  
H. W. Klein-Gebbinck ◽  
P. V. Blenis ◽  
Y. Hiratsuka
Keyword(s):  
Nearest Neighbor ◽  
Lodgepole Pine ◽  
Lateral Roots ◽  
Spatial Relationship ◽  
Individual Tree ◽  
Inoculum Sources ◽  
Nearest Neighbor Analysis ◽  
Inoculum Source ◽  
Pine Stands ◽  
Root Collar

Juvenile lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) were excavated at three sites near Hinton, Alberta. In all cases in which Armillariaostoyae (Romagn.) Herink had become established in the root collar or taproot, it was also able to colonize lateral roots. In cases in which only lateral roots were infected, subsequent colonization generally was primarily distal to the point of infection. Rhizomorphs were associated with 89% of 21 infected roots, whereas only 19% of 70 roots with no associated rhizomorphs were infected. Stumps, roots, and debris from the previous generation of trees were the inoculum sources for 78% of 36 infected juvenile trees, and infected regeneration served as the inoculum source for the remaining trees. Rhizomorphs occasionally were attached to the roots or rhizomes of plants other than pine, especially fireweed (Epilobiumangustifolium L.). There was no spatial relationship between stumps and symptomatic trees. Nearest neighbor analysis indicated that the likelihood of an individual tree developing symptoms was dependent on whether trees within 0.15 m were dead or dying but independent of the apparent health of trees at greater distances.

scholarly journals Individual Tree and Stand Level Influences on the Growth, Vigor, and Decline of Red Oaks in the Ozarks

2008 ◽  
Vol 54 (1) ◽  
pp. 8-20 ◽  
Author(s):  
Steven L. Voelker ◽  
Rose-Marie Muzika ◽  
Richard P. Guyette
Keyword(s):  
High Mortality ◽  
Basal Area ◽  
Boundary Line ◽  
Oak Decline ◽  
Competitive Growth ◽  
Crown Condition ◽  
Individual Tree ◽  
Growth Environment ◽  
Red Oaks ◽  
Dead Trees

Abstract Repeated oak decline and mortality events have occurred in the Ozark region for decades and probably longer. We sampled an age sequence of 1,259 black and scarlet oaks (Quercus velutina Lam. and Quercus coccinea Muench.) to better describe the process of oak decline and mortality in the red oak group (subgenera Erythrobalanus). Trend in basal area increment (BAI) over the most recent 40 years was used to establish three vigor classes for trees with decreasing, stable, or increasing growth (Declining, Stable, or Healthy). We compared crown condition measures with absolute BAI and boundary line BAI, a measure of radial growth adjusted for tree size. A pulse of mortality was found to occur just subsequent to the most recent drought, although decline often started decades previously. Time series of individual tree BAI suggests that half of all oak decline events were incited by one or two drought-related step-changes in growth and variance. Predisposing factors to decline generally showed significant but weak relationships with crown conditions. Surviving oaks growing in high-mortality stands had poorer crown conditions and grew more slowly than trees in low-mortality stands. When recently dead trees were accounted for, the same high-mortality stands had significantly greater predecline basal area and stocking than low-mortality stands. Thus, a less competitive growth environment may afford some buffer to drought stress before oak decline but does not appear to help afflicted stands improve their growth and vigor.

Opportunistic Colorectal Cancer Screening using Colonoscopy. Comparative Results between two Historical Cohorts in Bucharest, Romania

2015 ◽  
Vol 24 (2) ◽  
pp. 171-176 ◽  
Author(s):  
Elena Mirela Ionescu ◽  
Tudor Nicolaie ◽  
Serban Ion Gologan ◽  
Ana Mocanu ◽  
Cristina Ditescu ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Screening Program ◽  
Advanced Adenoma ◽  
Detection Rates ◽  
Incidence And Mortality ◽  
Organized Screening Program ◽  
History Of ◽  
Comparative Results ◽  
Asymptomatic Individuals ◽  
Second Period

Background & Aims: Even though Romania has one of the highest incidence and mortality in colorectal cancer (CRC) in Europe, there is currently no organized screening program. We aimed to assess the results of our opportunistic CRC screening using colonoscopy.Methods: A single center retrospective study to include all opportunistic screening colonoscopies performed in two 18 month periods (2007-2008 and 2012-2013) was designed. All asymptomatic individuals without a personal or family history of adenoma or CRC and with complete colonoscopy performed in these two time periods were included.Results: We included 1,807 individuals, 882 in the first period, 925 in the second period. There were 389 individuals aged below 50, 1,351 between 50 and 75 and 67 older than 75 years. There were 956 women (52.9%), with a mean age of 58.5 (median 59, range 23-97). The detection rates were 12.6% for adenomas (6.1% for advanced adenoma) and 3.4% for adenocarcinoma. Adenoma incidence (4.9% in subjects under 50, 14.7% in those aged 50 to 75, and 16.4% in those older than 75, p<0.0001) and size (6.3mm in subjects younger than 50, 9.2mm in those 50 to 75 and 10.8mm in those older than 75, p=0.015) significantly increased with age. Adenoma incidence increased in the second period (14.8% vs. 10.3%, p=0.005), while adenoma size decreased in the second period (8.4mm vs. 10mm, p=0.006). There were no procedure related complications.Conclusions: The neoplasia detection rate was 16% (12.6% adenoma, 3.4% adenocarcinoma). Adenoma incidence and size increased with age in both cohorts. In the second screening period significantly more and smaller adenomas were detected.

INVENTARISASI JAMUR MAKROSKOPIS FILUM ASCOMYCOTA DI KAWASAN UNIVERSITAS TANJUNGPURA PONTIANAK KALIMANTAN BARAT

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Repita Kristin ◽  
Rahmawati Rahmawati ◽  
Mukarlina Mukarlina
Keyword(s):  
Morphological Characteristics ◽  
Microscopic Fungi ◽  
Dead Trees

Ascomycota is a microscopic fungi and a fraction of macroscopic, unicellular and multicellular fungi. The research of Ascomycota phylum macroscopic fungi inventory research aims to determine the type macroscopic fungi of Ascomycota phylum members in Tanjungpura University Area, Pontianak, West Borneo. The sample was taken by using Cruise Method and identified by matching morphological characteristics of the specimens with the identification book. Ascomycota  identification of macroscopic fungi samples of Ascomycota phylum based on morphological characteristics with the identification books. The results study found have 3 macroscopic fungi species consisting of 2 classes, 2 orders, 2 families, and 2 genera. In addition, Ascomycota found in Tanjungpura University Area, Pontianak, West Borneo, grow mostly on the substrate originated from dead trees.

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