Developing nonlinear additive tree crown width models based on decomposed competition index and tree variables

Crown development is closely related to the biomass and growth rate of the tree and its width(CW)is an important covariable in growth and yield models and in forest management.To date,various CW models have been proposed.However,limited studies have explicitly focused on additive and inherent correlation of crown components and total CW as well as the influence of competition on crown radius from the corresponding direction.In this study,two model systems were used,i.e.,aggregation method system(AMS)and disaggregation method system(DMS),to develop crown width additive model systems.For calculating spatially explicit competition index(CI),four neighbor tree selection methods were evaluated.CI was decomposed into four cardinal directions and added into the model systems.Results show that the power model form was more proper for our data to fit CW growth.For each crown radius and total CW,height to the diameter at breast height(HDR)and basal area of trees larger than the subject tree(BAL)significantly contributed to the increase of prediction accuracy.The 3-m fixed radius was optimal among the four neighborhoods selection ways.After adding decomposed competition Hegyi index into model systems AMS and DMS,the prediction accuracy improved.Of the model systems evaluated,AMS based on decomposed CI provided the best performance as well as the inherent correlation and additivity properties.Our study highlighted the importance of decomposed CI in tree CW modelling for additive model systems.This study focused on methodology and could be applied to other species or stands.

Pine wilt disease detection in high-resolution UAV images using object-oriented classification

Pine wilt disease(PWD)is currently one of the main causes of large-scale forest destruction.To control the spread of PWD,it is essential to detect affected pine trees quickly.This study investigated the feasibility of using the object-oriented multi-scale segmentation algorithm to identify trees discolored by PWD.We used an unmanned aerial vehicle(UAV)platform equipped with an RGB digital camera to obtain high spatial resolution images,and multiscale segmentation was applied to delineate the tree crown,coupling the use of object-oriented classification to classify trees discolored by PWD.Then,the optimal segmentation scale was implemented using the estimation of scale parameter(ESP2)plug-in.The feature space of the segmentation results was optimized,and appropriate features were selected for classification.The results showed that the optimal scale,shape,and compactness values of the tree crown segmentation algorithm were 56,0.5,and 0.8,respectively.The producer’s accuracy(PA),user’s accuracy(UA),and F1 score were 0.722,0.605,and 0.658,respectively.There were no significant classification errors in the final classification results,and the low accuracy was attributed to the low number of objects count caused by incorrect segmentation.The multi-scale segmentation and object-oriented classification method could accurately identify trees discolored by PWD with a straightforward and rapid processing.This study provides a technical method for monitoring the occurrence of PWD and identifying the discolored trees of disease using UAV-based high-resolution images.

Acute-on-Chronic Liver Failure Precipitated by Severe Acute Respiratory Syndrome Coronavirus 2 Infection in a Patient with Hepatitis B Virus-Related Cirrhosis: A Case Report

We present a case of acute-on-chronic liver failure(ACLF)in a patient with hepatitis B virus(HBV)-related decompensated cirrhosis and coronavirus disease 2019(COVID-19).A 58-year-old woman with HBV-related and decompensated cirrhosis without any anti-viral treatment previously was admitted to the hospital due to a confirmed severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection.On admission,she was in stable condition.Thoracic computed tomography(CT)and laboratory findings showed no significant abnormalities.Entecavir was initiated promptly for HBV,while antiviral therapy and supportive treatment were initiated for COVID-19.Her lung infection exacerbated after 10days of recurrent fever despite treatments,and there were signs of HBV reactivation.ACLF and multiple organ dysfunction syndrome developed rapidly from day 10 to day 19.The patient’s clinical deterioration was also consistent with pneumonia progression and elevated interleukin 6 levels.SARS-CoV-2 likely precipitated ACLF in cirrhotic patients,either by inducing HBV flare or serving as an acute insult directly.This study discussed the underlying mechanisms of this process and management details.Monitoring HBV status is necessary,and inflammatory parameters might be valuable.HBV suppression should be initiated early,and variceal hemorrhage primary prevention might be beneficial in COVID-19 patients with cirrhosis.