Tree Generation Research Articles

Outlier detection using iterative adaptive mini-minimum spanning tree generation with applications on medical data.

As an important technique for data pre-processing, outlier detection plays a crucial role in various real applications and has gained substantial attention, especially in medical fields. Despite the importance of outlier detection, many existing methods are vulnerable to the distribution of outliers and require prior knowledge, such as the outlier proportion. To address this problem to some extent, this article proposes an adaptive mini-minimum spanning tree-based outlier detection (MMOD) method, which utilizes a novel distance measure by scaling the Euclidean distance. For datasets containing different densities and taking on different shapes, our method can identify outliers without prior knowledge of outlier percentages. The results on both real-world medical data corpora and intuitive synthetic datasets demonstrate the effectiveness of the proposed method compared to state-of-the-art methods.

Quantifying the impact of scenario tree generation and reduction methods on the solution of the short-term hydroscheduling problem

Quantifying the impact of scenario tree generation and reduction methods on the solution of the short-term hydroscheduling problem

Clock tree generation by abutment in synchoros VLSI design

Synchoros VLSI design style has been proposed as an alternative to standard cell-based design. Standard cells are replaced by synchoros, large grain, VLSI design objects called SiLago (Silicon Lego) blocks. This new design style eliminates the need to synthesise ad hoc wires of any type: functional and infrastructural. SiLago blocks are organised into region instances. In a region instance, communication amongst SiLago blocks is synchronous and happens over a regional network on chip (NoC), whose fragments are also absorbed into SiLago blocks. Consequently, the regional NoCs get created by the abutment of SiLago blocks. The clock tree used in a region is called a regional clock tree (RCT). The synchoros VLSI design style requires that the RCT, like the regional NoCs, is also created by abutting its fragments. The RCT fragments are absorbed within the SiLago blocks. The RCT created by the abutment is not an ad-hoc clock tree but a structured and predictable design with known cost metrics. The design of such an RCT is the focus of this paper. The scheme is scalable, and we demonstrate that the proposed RCT can be generated for valid VLSI designs of ∼1.5 million gates. The RCT created by abutment is correct by construction, and its properties are predictable. Additionally, we present an in-depth description of the method used to find the optimal configuration for the proposed design. We have validated the generated RCTs with static timing analysis to validate the correct-by-construction claim. Finally, we show that the cost metrics of the SiLago RCT is comparable to the one generated by commercial EDA tools.

Integrating the Rate of Moisture Loss into Needle Retention Testing to Improve the Selection of Balsam Fir (Abies balsamea) for Use as Christmas Trees

A study was conducted to identify balsam fir (Abies balsamea) for use in Christmas tree breeding programs in Northeastern North America. A total of sixty-four phenotypically good trees were identified from a provincial clonal seed orchard in New Brunswick, a multi-aged natural seed production area in Nova Scotia, and an operational plantation in Quebec, Canada. Trees were selected for good growth and form, numbers, and vigour of internodal branches, acceptable crown taper, needle colour, age class, branch angle, needle configuration, and freedom from insects and diseases or deformities, all traits deemed desirable in a Christmas tree. Three branches from each tree were collected at two harvest dates each year, one early and one late during the normal harvesting season in 2020, 2021, and 2022. Qualitative assessments of colour and branch pliability were performed weekly in conjunction with needle loss rub tests. A quantitative assessment of moisture loss was conducted weekly by measuring branch weights. The combination of qualitative and quantitative assessments was used to identify 7 of the 64 trees for which one or more tested branches consistently remained green and pliable, retained the majority of their needles, and lost moisture at a significantly reduced rate in all six testing periods. Grafts of the seven ‘Select’ trees are currently being integrated into seed orchards in the three participating provinces. These second-generation seed orchards are part of breeding programs designed to develop Christmas trees that will perform well under warm fall conditions, an outcome of climate change. The results from this study combined with the progeny testing of the ‘Select’ trees will be used to test for the heritability of needle retention, a key trait for the next generation of Christmas trees in the Northeast.

Rhizomorph: The Coordinated Function of Shoots and Roots

Computer graphics has dedicated a considerable amount of effort to generating realistic models of trees and plants. Many existing methods leverage procedural modeling algorithms - that often consider biological findings - to generate branching structures of individual trees. While the realism of tree models generated by these algorithms steadily increases, most approaches neglect to model the root system of trees. However, the root system not only adds to the visual realism of tree models but also plays an important role in the development of trees. In this paper, we advance tree modeling in the following ways: First, we define a physically-plausible soil model to simulate resource gradients, such as water and nutrients. Second, we propose a novel developmental procedural model for tree roots that enables us to emergently develop root systems that adapt to various soil types. Third, we define long-distance signaling to coordinate the development of shoots and roots. We show that our advanced procedural model of tree development enables - for the first time - the generation of trees with their root systems.

The Future of European Beech in Northern Germany—Climate Change Vulnerability and Adaptation Potential

Earth’s forests are increasingly exposed to climate risks through climate change-related drought and heat waves. Here, we review the climate vulnerability of European beech (Fagus sylvatica), the most abundant tree species of Central Europe’s temperate forests, and its adaptation potential to a hotter and drier climate in northern Germany, close to the center of the species’ distribution range. About two-thirds of the studied beech forests show persistent negative growth trends of their dominant trees since the onset of rapid warming in the early 1980s, driven primarily by long-term deterioration of the climatic water balance (CWB) in summer and, locally, long-term decrease in June precipitation. Lower water storage capacity of the soil increases the climate sensitivity of growth. Even though beech populations of drier sub-regions reveal some acclimation to drought (reduced stomatal conductance, turgor loss point reduction, higher C allocation to roots), they are more climate-vulnerable than populations at moister sites, visible in larger growth decreases and greater CWB sensitivity of growth. Even though beech mortality is still lower in the study region than in other parts of Central Europe, our results identify beech forest regions with <350 mm growing-season precipitation as vulnerable to recent climate conditions, which refers to half of the study region. With further climate warming and aridification, most of northern Germany likely will become unfavorable for beech growth within the next tree generation, which suggests choosing in many production forests alternative, more drought- and heat-resistant timber species.

Image Subset Union for Compressed Image Sets in Cloud Servers

Image deletion and image insertion, the current commonly used two kinds of image set management, refer to removing compressed images from and adding new photos to a compressed image set, respectively. However, they do not deal with well the problem of the combination of images selected from multiple compressed image sets. To address this issue, in this paper we first propose an image subset union algorithm for compressed image sets. Image subset union aims to integrate image subsets derived from multiple compressed image sets into a new compressed image set. First, we put forward a way to identify the root vertex candidate of the new compressed image set. Second, we classify all the images of image subsets into three categories: images needed to be re-encoded, images needed to be only decoded, and images unneeded to be re-encoded or decoded. Third, we also employ minimum spanning tree production, a proposed vertex layer candidate assignment method, depth- and subtree-constrained minimum spanning tree generation, as well as image re-encoding to build the new compressed image set. Experimental results show that our proposed algorithm can effectively accomplish image subset union with low complexity.

A Novel Approach to Coronary Artery Tree Generation

A Novel Approach to Coronary Artery Tree Generation

Pollination success of Fraxinus excelsior L. in the context of ash dieback

Key messagePaternity analyses show that effective pollination of ash (Fraxinus excelsior L.) in a seed orchard and a floodplain forest affected by ash dieback is more likely to be facilitated by healthier males. Thereby, natural selection can have a positive effect on the health of future generations.ContextOngoing ash dieback and increasing fragmentation of ash populations may result in reduced pollen flow, which can reduce pollination success of future generations of ash trees. Therefore, it is essential to further improve our understanding of gene flow patterns, especially with respect to ash dieback.AimsIn this study, paternity analyses were conducted in a seed orchard and a floodplain forest in Germany in 2018 to explain the relationship between pollination success and the health status of ash trees and distances of effective pollen transport.MethodsCambium samples (i.e., from twigs and stumps) were collected from 251 ash trees (putative father and mother trees) for genotyping, and the health status of each tree was documented using a scoring system to evaluate vitality. Additionally, seeds were harvested from 12 mother trees per site. Genetic analyses using nuclear microsatellites were performed to determine paternal trees. Paternities were assigned based on the likelihood model implemented in the Cervus 3.0.7 software.ResultsOur results showed that the average pollination distance was 76 m in the seed orchard and 166 m in the floodplain forest. In general, pollination success decreased substantially with increasing distance to the mother tree. Despite the dense tree cover in the floodplain forest, pollen were transported over long distances (greater than 550 m), suggesting that non-local sources also play a role in pollination. This is supported by the foreign pollen input identified in the seed orchard (66.5%). Self-pollination was detected only to a very small extent, and thus had no major influence on reproduction. In addition, both healthy and slightly diseased father trees showed similar mating success. However, this was not the case for the severely diseased ash trees (more than 50% of crown damage) because only a few offspring could be assigned to them. Nevertheless, in contrast to the floodplain forest, there was no significant correlation between damage classes and pollination success in the seed orchard.ConclusionLong-distance pollen transport contributes to the connectivity of ash trees in the landscape. Additionally, both healthy and slightly diseased fathers have a greater contribution to pollination, thus potentially improving the health of the next generation of ash trees. Moreover, gene flow between stepping stone populations is necessary to ensure the positive impact on the genetic diversity of ash populations in the future.

Fine-scale genetic structure of Magnolia iltisiana in forest regeneration sites with a history of selective logging

Background: Selective logging is a frequent practice in the Tropical Montane Cloud Forest which can impact forest regeneration and the genetic makeup of successive generations of trees. The spatial clustering of genetically related individuals, fine-scale genetic structure (FSGS), can develop from the reduction of gene dispersal and the decrease in the number of reproductive individuals at the local scale due to selective logging.
 Questions: In regeneration sites with a history of selective logging, does FSGS differ from a site without such a history? Is FSGS stronger in seedlings and saplings relative to juveniles and adults? Is genetic diversity similar among life stages and sites?
 Studied species: Magnolia iltisiana an endemic tree.
 Study site and dates: Sierra de Manantlan Biosphere Reserve, Jalisco, Mexico.
 2020.
 Methods: We evaluated genetic diversity, genetic structure, and FSGS across four life stages (seedlings, saplings, juveniles, and adults) by genotyping 211 individuals with seven nuclear microsatellite loci in two regeneration and one conserved site.
 Results: We found statistically significant FSGS in the two regeneration sites only for seedlings and saplings, while no evidence of FSGS was detected in the conserved site. No differences in genetic diversity estimates and structure were found among life stages.
 Conclusions: Our study does not suggest an effect of selective logging on genetic diversity on the contrasted conditions and an FSGS pattern only in the earlier stages of the regeneration sites in M. iltisiana.

Aeromonas nosocomial cluster: Investigation review of possible modes of transmission

Background:Aeromonas is a gram-negative rod known to be present in water, sewage and soil which may cause infections especially in immunocompromised hosts. Cases of Aeromonas gastroenteritis have been associated with warmer weather. In total, 3 patients with extensively drug resistant (XDR) Aeromonas were identified at our facility between August and September 2022 on 2 intensive care units (ICUs). Our infection prevention, microbiology, and facility teams investigated these cases to determine whether a common source could be the mode of transmission. Methods: To first determine whether patients’ Aeromonas specimens were related, whole-genome sequencing (WGS) of the clinical isolates from 3 patients was performed using the Illumina DNA Prep Kit and Illumina MiSeq. Sequencing analysis was performed using CLC Genomics Workbench for de novo assembly, single-nucleotide polymorphisms (SNP) calling, and tree generation, Geneious Prime for reference-based assembly, annotation, and quality assessment, KmerFinder for reference identification, and the Comprehensive Antibiotic Resistance Database for resistance gene detection via protein homology. Chart review revealed that patients occupied multiple rooms between 2 ICUs (Fig. 1). Because water is a known source of Aeromonas, facility records were reviewed for water intrusion events. This analysis identified several cases in the affected patient and surrounding rooms. Sinks and faucets from 10 rooms were swabbed followed by direct plating on blood, MacConkey agar, and Aeromonas-selective cefsulodin-Irgasan-novobiocin (CIN) agar plates. Lastly, the city temperatures before and after positive cases were reviewed to identify whether any correlation could be shown between temperature and timing of infection. Results: WGS analysis revealed that the 3 Aeromonas isolates (all identified as A. hydrophila) were not directly related (minimum distance, 934 SNPs) and harbored between 4 and 19 unique antimicrobial resistance genes, including co-occurring carbapenemases VIM-2 and KPC-3 in 1 isolate and OXA-232 in another. Of the 20 environmental samples, few gram-negative nonfermenting bacteria and no Aeromonas isolates were detected (Fig. 1). Elevated city did loosely proceed patient cases of Aeromonas, suggesting a possible role of higher temperature, which may have promoted the growth of Aeromonas during the periods of the 3 cases and thus may contribute to the nosocomial infections (Fig. 2). Conclusions: Although our investigation did not reveal a definitive cause for the Aeromonas cases, it did show the importance prompt identification and investigation can have on mitigating the spread of a cluster. Our facility has not identified any additional nosocomial cases. Monitoring water intrusion events and plans for remediation continue to be a priority.Disclosures: None

Genetic relatedness among Neisseria gonorrhoeae isolates in southeastern Michigan

Background: Antimicrobial resistance (AMR) in Neisseria gonorrhoeae (NG) is an emerging public health crisis. Whole-genome sequencing (WGS) is an efficient way of predicting AMR determinants and their spread in the population. In a previous study, genotype–phenotype correlation analyses among NG isolates to determine antimicrobial resistance revealed discordance for azithromycin (AZM) and ceftriaxone (CRO) compared to other antibiotics. We investigated the evolutionary relatedness of NG isolated from patients with sexually transmitted infection (STI) using WGS in southeastern Michigan. Methods: Isolates, corresponding demographic data, and minimum inhibitory concentrations (MIC) via E-test (CRO) and broth microdilution (AZM) were obtained from the Michigan Department of Health and Human Services. Whole-genome libraries were prepared using the QIAseq FX kit followed by sequencing on a NovaSeq6000 (>200X Coverage); samples were aligned to NG reference strain TUM19854 (NZ_AP023069.1) using Snippy before phylogenetic tree generation using Neighbor-joining clustering on the core.aln files. Phylogenetic trees were visualized using ATGC:PRESTO. Results: In total, 38 isolates were analyzed. Demographic data and susceptibility testing results are noted in Table 1. Most isolates were from males (63%), Blacks (44.7%), individuals living in Detroit City proper (47.3%), and those with unknown HIV status (55.2%). More than one-third had prior STI, including NG. All isolates were susceptible to CRO (CLSI susceptible breakpoint MIC, 1). Within the phylogenetic tree, 8 main branches were identified (Fig. 1). Moreover, 1 branch contained a cluster with 12 closely related isolates, which included the 9 isolates with nonsusceptible AZM. Nearly all isolates in that cluster had been collected from Detroit City proper and Wayne County, suggesting epidemiological overlap and potential spread of resistant strains in those counties.Conclusions: Comparative whole-genome and phylogenetic analyses among a subset of NG isolates revealed clustering of AZM resistance strains, suggesting a genomic component to AMR. Further studies are needed to determine the utility of WGS in diagnosis, outbreak investigations, and management of NG infections.Disclosures: None

An electrical analog permeability model assessing fluid flow in a decellularized organ

Background and objectiveIn recellularization, cell-seeding efficiency refers to the uniform distribution of cells across the decellularized organ, which should be enhanced to ensure effective functioning. During cell seeding, flow dynamics influence the distribution of cells because the driving force of cell movement is the fluid force. However, after decellularization, because of flow permeability through the vessel wall, the fluid pressure and velocity in the vessels of vascular trees are significantly reduced compared with those in the native organ, which might affect cell seeding efficiency. Therefore, it is necessary to assess the flow characteristics in the vessels of decellularized organs to select appropriate seeding conditions. Although electrical analog models have been widely used to investigate the flow distribution in organs, current models do not reflect the permeable conditions. This study proposes a model to extend the conventional electrical analog model to simulate the flow characteristics in decellularized organs. MethodsA resistor reflecting permeable flow was added to the original electrical analog model to describe the permeable conditions in the decellularized organs. Decellularization and pressure drop measurements of the kidney were also conducted for model development, calibration, and validation. The developed model was then applied to a decellularized kidney to reveal changes in flow characteristics. ResultsThe resistance calculation of permeable flow was determined for each generation of vascular trees. The coefficient of permeability can be indicated by the measured flow exiting through the outlet or the pressure drop across the decellularized organ. The developed permeability model had a qualitative and quantitative agreement with the experimental data without calibration. The results of the permeability model for the decellularized kidney indicated significant reductions of up to 70% in the flow rate and pressure of the organ compared to the native kidney. ConclusionsThe developed model can simulate the flow characteristics in each individual vessel of decellularized organs. The results from the model can be used to assess the optimal flow rate condition for the cell seeding process.

Predictors of Candidemia during Febrile Episode in Lymphoreticular Malignancy Affecting Paediatric Population.

Limited studies on candidemia in malignancy in the paediatric population from developing countries show a high incidence, high morbidity and a unique epidemiology as compared to developed nations. Our prospective observational study aimed to explore the prevalence of invasive candidiasis, especially candidemia, in febrile paediatric patients with lymphoreticular malignancy. A sample size of 49 children, with 100 recorded febrile episodes was studied. The relevance of candida colonization and mannan antigen detection as indicators of impending candidemia was evaluated. Genotypic identification of the yeast isolates was followed by sequence analysis using the NCBI-BLAST program, and the generation of the phylogenetic tree using MEGA 6.0 software. We observed a 5% prevalence of candidemia among febrile paediatric patients with lymphoreticular malignancy, predominantly caused by non-albicans candida. Colonization at multiple anatomical sites decreased from day 1 to day 8 of febrile episodes. Significant candida colonization (colonization index ≥0.5) was seen in a larger proportion of candidemia patients on day 1 and day 4 (p < 0.001) displaying a definite association between the two. The receiver operator characteristic (ROC) curve analysis for mannan antigen level revealed a cut-off of ≥104.667 pg/mL, suitable for predicting candidemia with a sensitivity of 100%, specificity of 92% and area under ROC value of 0.958 (95% CI: 0.915-1; p < 0.001). A phylogenetic tree with three population groups, clade 1, 2 and 3, consisting of Candida auris (1), Candida tropicalis (2) and Candida parapsilosis (2), respectively, was generated. The diagnosis of candidemia based on mannan antigen detection gives early results and has high negative predictive values. It can be combined with other biomarkers to increase sensitivity, specificity and positive predictive value.

Towards Globally Optimal Design of Multipliers for FPGAs

The design of a multiplier typically consists of three steps: (1) partial product generation, (2) compressor tree design and (3) the selection of the final adder. Conventionally, these three steps are performed consecutively. However, when targeting FPGAs, there are many possibilities in all three design steps that heavily influence each other. This proposal presents for the first time a holistic optimization, combining all three optimization steps yielding a minimum amount of look-up-tables (LUTs) while it can also guarantee the minimal number of (pipeline) stages. An ILP-formulation for the determination of a combined, globally optimal solution for the multiplier tiling, compressor tree generation and final adder selection is proposed. With globally optimal we mean that the best solution is found for a given set of sub-multipliers for partial product generation, compressors and final adder.This allows to improve the quality and evaluate the limitations of existing heuristic 3-step approaches. It is shown experimentally for the example of Xilinx FPGAs, that globally optimal solutions can be obtained for multiplier sizes of practical relevance, leading to significant LUT reductions. Additional packing density experiments show that a significantly larger number of multiplier instances can be mapped to the same device.

Recognition of Timestamps and Reconstruction of the Line of Organism Development

In this work, an artificial neural network is used to recognize timestamps of evolution. Timestamps are associated with outliers determined during the recognition of the genome attractors of organisms. The aim of this work is to present a new method of penetrating deep into evolution using the recognized timestamps. To achieve this aim, the neural networks of different number of layers were implemented in order to check the influence of the number of layers on the visibility of the timestamps. Moreover, the teaching process was repeated 10 times for each implemented neural network. The recognition of each organism evolution was also repeated 10 times for each taught neural network to increase the reliability of the results. It is presented, among other findings, that during the recognition of the timestamps of evolution not only the number of homologous comparisons and the lengths of compared sequences are important but also the distribution of similarities between sequences. It is also presented that the recognized timestamps allow for travel between genome attractors and reconstruct the line of organism development from the most advanced to the most primitive organisms. The results were validated by determining timestamps for exemplary sets of organisms and also in relation to semihomology approach and by phylogenetic tree generation.

E3 ubiquitin ligase PbrATL18 is a positive factor in pear resistance to drought and Colletotrichum fructicola infection

The Arabidopsis Tóxicos en Levadura (ATL) protein is a subfamily of the E3 ubiquitin ligases, which exists widely in plants and is extensively involved in plant growth and development. Although the ATL family has been identified in other species, such as Arabidopsis, Oryza sativa, and grapevine, few reports on pear ATL gene families have been reported. In this study, 92 PbrATL genes were identified and analyzed from the Pyrus breschneideri genome. Motif analysis and phylogenetic tree generation divided them into nine subgroups, and chromosome localization analysis showed that the 92 PbrATL genes were distributed in 16 of 17 pear chromosomes. Transcriptome data and quantitative real-time polymerase chain reaction (qRT-PCR) experiments demonstrated that PbrATL18, PbrATL41, and PbrATL88 were involved in both pear drought resistance and Colletotrichum fructicola infection. In addition, Arabidopsis thaliana overexpressing PbrATL18 showed greater resistance to drought stress than the wild type (WT), and PbrATL18-silenced pear seedlings showed greater sensitivity to drought and C. fructicola infection than the controls. PbrATL18 regulated plant resistance by regulating chitinase (CHI), phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) activities. This study provided a reference for further exploring the functions of the PbrATL gene in drought resistance and C. fructicola infection.

A Possible Aquatic Origin of the Thiaminase TenA of the Human Gut Symbiont Bacteroides thetaiotaomicron

TenA thiamin-degrading enzymes are commonly found in prokaryotes, plants, fungi and algae and are involved in the thiamin salvage pathway. The gut symbiont Bacteroides thetaiotaomicron (Bt) produces a TenA protein (BtTenA) which is packaged into its extracellular vesicles. An alignment of BtTenA protein sequence with proteins from different databases using the basic local alignment search tool (BLAST) and the generation of a phylogenetic tree revealed that BtTenA is related to TenA-like proteins not only found in a small number of intestinal bacterial species but also in some aquatic bacteria, aquatic invertebrates, and freshwater fish. This is, to our knowledge, the first report describing the presence of TenA-encoding genes in the genome of members of the animal kingdom. By searching metagenomic databases of diverse host-associated microbial communities, we found that BtTenA homologues were mostly represented in biofilms present on the surface of macroalgae found in Australian coral reefs. We also confirmed the ability of a recombinant BtTenA to degrade thiamin. Our study shows that BttenA-like genes which encode a novel sub-class of TenA proteins are sparingly distributed across two kingdoms of life, a feature of accessory genes known for their ability to spread between species through horizontal gene transfer.

In silico simulation of hepatic arteries: An open-source algorithm for efficient synthetic data generation.

In silico testing of novel image reconstruction and quantitative algorithms designed for interventional imaging requires realistic high-resolution modeling of arterial trees with contrast dynamics. Furthermore, data synthesis for training of deep learning algorithms requires that an arterial tree generation algorithm be computationally efficient and sufficiently random. The purpose of this paper is to provide a method for anatomically and physiologically motivated, computationally efficient, random hepatic arterial tree generation. The vessel generation algorithm uses a constrained constructive optimization approach with a volume minimization-based cost function. The optimization is constrained by the Couinaud liver classification system to assure a main feeding artery to each Couinaud segment. An intersection check is included to guarantee non-intersecting vasculature and cubic polynomial fits are used to optimize bifurcation angles and to generate smoothly curved segments. Furthermore, an approach to simulate contrast dynamics and respiratory and cardiac motion is also presented. The proposed algorithm can generate a synthetic hepatic arterial tree with 40 000 branches in 11 s. The high-resolution arterial trees have realistic morphological features such as branching angles (MAD with Murray's law ), radii (median Murray deviation ), and smoothly curved, non-intersecting vessels. Furthermore, the algorithm assures a main feeding artery to each Couinaud segment and is random (variability=0.98 ± 0.01). This method facilitates the generation of large datasets of high-resolution, unique hepatic angiograms for the training of deep learning algorithms and initial testing of novel 3D reconstruction and quantitative algorithms designed for interventional imaging.

Efficacy of Biological and Chemical Control Agents against Heterobasidion Spore Infections of Norway Spruce and Scots Pine Stumps on Drained Peatland

Treatment of conifer stumps with a control agent effectively prevents Heterobasidion spore infections in summer cuttings and protects the residual stand and the next tree generation from damage caused by Heterobasidion root rot. Thus far, stump treatment experiments have been carried out in mineral soils, and no information is available on the efficacy of stump treatment agents in boreal peatland conditions. In the present study, biological and chemical control agents (Phlebiopsis gigantea and urea, respectively) were tested in Scots pine and Norway spruce stands subjected to thinning, cap cutting, and clearcutting on drained peatland in Central Finland. The control efficacy of urea was high in both spruce and pine stumps (on average 99.5 and 85.3%, respectively), while the efficacy of P. gigantea was highly variable on both tree species and ranged from full protection down to negative control effect, i.e., there were more Heterobasidion infections on the treated than untreated half of the stumps. The moisture content of the stump wood or the thickness of the peat layer did not affect the control efficacy of either control agent. These results emphasize a need for further studies to determine the reasons for the unsteadiness of the biological control in peatland conditions.