Local Forest Research Articles

Wall-to-wall mapping of carbon loss within the Chornobyl Exclusion Zone after the 2020 catastrophic wildfire

Key messageWe propose a framework to derive the direct loss of aboveground carbon stocks after the 2020 wildfire in forests of the Chornobyl Exclusion Zone using optical and radar Sentinel satellite data. Carbon stocks were adequately predicted using stand-wise inventory data and local combustion factors where new field observations are impossible. Both the standalone Sentinel-1 backscatter delta (before and after fire) indicator and radar-based change model reliably predicted the associated carbon loss.ContextThe Chornobyl Exclusion Zone (CEZ) is a mosaic forest landscape undergoing dynamic natural disturbances. Local forests are mostly planted and have low ecosystem resilience against the negative impact of global climate and land use change. Carbon stock fluxes after wildfires in the area have not yet been quantified. However, the assessment of this and other ecosystem service flows is crucial in contaminated (both radioactively and by unexploded ordnance) landscapes of the CEZ.AimsThe aim of this study was to estimate carbon stock losses resulting from the catastrophic 2020 fires in the CEZ using satellite data, as field visitations or aerial surveys are impossible due to the ongoing war.MethodsThe aboveground carbon stock was predicted in a wall-to-wall manner using random forest modelling based on Sentinel data (both optical and synthetic aperture radar or SAR). We modelled the carbon stock loss using the change in Sentinel-1 backscatter before and after the fire events and local combustion factors.ResultsRandom forest models performed well (root-mean-square error (RMSE) of 22.6 MgC·ha−1 or 37% of the mean) to predict the pre-fire carbon stock. The modelled carbon loss was estimated to be 156.3 Gg C (9.8% of the carbon stock in burned forests or 1.5% at the CEZ level). The standalone SAR backscatter delta showed a higher RMSE than the modelled estimate but better systematic agreement (0.90 vs. 0.73). Scots pine (Pinus sylvestris L.)-dominated stands contributed the most to carbon stock loss, with 74% of forests burned in 2020.ConclusionThe change in SAR backscatter before and after a fire event can be used as a rough proxy indicator of aboveground carbon stock loss for timely carbon map updating. The model using SAR backscatter change and backscatter values prior to wildfire is able to reliably estimate carbon emissions when on-ground monitoring is impossible.

Reconstructing Long‐Term Forest Age of China by Combining Forest Inventories, Satellite‐Based Forest Age and Forest Cover Data Sets

AbstractForest age is one of the most important ecosystem characters for accurately estimating the magnitude and potential of carbon sink in forest ecosystems. During the past 40 years, national ecological restoration projects have led to the near doubling of the forest cover area in China, which has also substantially affected the dynamics of forest age. Therefore, there is an urgent need to generate long‐term forest age maps for China. This study reconstructed China forest age datasets (CFAD) from 1980 to 2015 at five year intervals at a 1 km spatial resolution by merging a satellite‐based forest age map in 2010 and forest cover dynamic maps from 1980 to 2015. The random forest method was used to reconstruct the forest age where forest age could not be inferred from the forest age base map in 2010 directly. CFAD showed a good agreement with the province‐level mean forest age derived from the several national forest inventories (R2 ranged from 0.66 to 0.86). In general, the younger forests are mainly distributed in southern and eastern China. The older forests are mainly distributed in the mountain areas of northeast, northwest and southwest China. The average age of China's forests increased from 18.2 to 44.0 years old from 1980 to 2015. Based on the current forest age and future afforestation planning, the average forest age in China is predicted to reach 71.6 years old in 2060. The CFAD provides an alternative data set to obtain improved estimates of local and national forest carbon sinks in China.

Intraspecific variation in sensitivity to habitat fragmentation is influenced by forest cover and distance to the range edge

The relative effects of habitat loss and fragmentation on biodiversity have been a topic of discussion for decades. While it is acknowledged that habitat amount can mediate the effects of habitat fragmentation, it is unclear what other factors may drive inter- and intraspecific variation in fragmentation effects and their implications for conservation. We tested whether the effects of forest fragmentation on 362 bird species' occurrence in the Atlantic Forest of Brazil are mediated by distance to geographic range edge and habitat amount, and whether these effects explain intraspecific variation across populations. Using a single binomial linear mixed effects model, we found that fragmentation had mostly negative effects on occurrence probability up to 1080 km from the species' range edge, independent of habitat amount. We also show that above this distance, fragmentation has predominantly positive effects, more accentuated in deforested landscapes. We demonstrate that fragmentation effects can be both positive and negative, indicating that different populations of the same species can respond differently depending on distance to range edge and local forest cover. Our results help clarify one of the drivers of contradictory results found in the fragmentation literature and highlight the importance of preventing habitat fragmentation for the conservation of endangered populations. Conservation initiatives should focus on minimising fragmentation closer to range edges of target species and in regions where species range edges overlap.

Community Forest Management: Weak States or Strong Communities?

Community forest management (CFM) has become an influential approach in the sustainable use, management, and conservation of forests worldwide. It ranges from community-based self-governance of local village forests to co-management approaches with state forest agencies in public forests. However, analyses show complex relationships between states and communities in CFM. At least three ideal types can be identified. The first refers to local communities that collectively decide to manage surrounding forests themselves due to a lack of state involvement. As a manager of the public good, such absence of the state may easily lead to deforestation and forest degradation that such communities wish to avoid. A second type refers to the co-management approaches of local communities and state forest agencies. Here, forest officials and community members cooperate in managing local forests. A final type refers to indigenous communities with strong customary forest institutions whose territorial claims are recognized by the state. While communities always need specific institutions, knowledge, and tenure rights in place to make CFM perform, each ideal type presupposes various degrees of state capacity and state autonomy. The article concludes that weak states (to some degree) and strong communities (of a certain kind) may indeed form a “convincing liaison” in CFM, although it is not the only arrangement that may produce (some) positive social and environmental impacts on the ground, as the cases explored illustrate.

Reconstructing the oaks’ growth patterns in Greece with the use of historical timber: Case studies from Western Peloponnese

Southern Greece is a region where available oak reference chronologies are still missing, making dendroarchaeology and dating of historical buildings rather challenging, if not impossible. In the current study we performed wood identification and dendroarchaeological analysis on timber from three historical buildings: the castles of Androusa and Koroni and the Church of Agios Dimitrios, in Western Peloponnese. The three monuments represent buildings of different uses covering different periods, but also sharing a common characteristic: oak was the only timber used in their construction, while the number of preserved timber elements is very limited. A dendroarchaeological examination of these three historical buildings, together with radiocarbon and wiggle-matching analysis, provided valuable chronological information for the local archaeologists, historians, and other scientists. Application of dendrochronological techniques has helped place the three buildings under study into the Ottoman period. Our results also show that timber was acquired most probably from local non-managed forests, which suggests that oak forests were present in the broader area at least from the late 15th to the first half of the 18th centuries. The discordance between dendrochronological and radiocarbon dates in one of the three cases highlights the need for further exploration of the study area through a combined implementation of both dendrochronological and radiocarbon dating analyses in order to develop well-replicated local oak chronologies. Our study also shows that dendroarchaeology can contribute significantly to the cultural and landscape history of Western Peloponnese even with an examination of limited number of preserved timber elements from historical buildings.

Rehabilitation plan for coal pit revegetation area East Kalimantan

The degraded mining area, especially the disposal area, must be reclaimed to preserve the possibility of its subsequent use in the future. The open pit rehabilition must ensure post-mining contributes powerfully to the ecosystem by restoring the production capacity and stability of the area. The exercise was applied to a nearly 0.5 Ha of open-pit coal mine conducted in cooperation between Korea and Indonesia to create a production forest that can ultimately support the environment. The objective of this work was to design mine pit reclamation plan through characterization physically and chemically the location by regenerating, checking the drainage system, analyzing soil fertility and the possibility of soil contamination and discovering fast growing local crop and forest plant species. The main focus is more on analyzing the soil condition affected by the acid mine drainage problem. The results showed that the northern restoration target site had the steep slope, characterized as acidic soil (pH was 4.2 – 4.6) with low exchangeable cation and low phosphate availability. The heavy metals did not exceed the contamination limit, so separate processing to prevent leaching of heavy metals is not required. Routine monitoring of the drainage system is important because it will affect the watering frequency and leaching control. Understanding the step by step mine rehabilitation can assist in designing reclamation efforts especially for revegetation purpose.

Developing a model for managing sustainable regional forest biomass resources: System dynamics-based optimization

In Japan, the number of plantation forests that must be harvested is increasing. Therefore, it is desirable to establish an operational system with a high efficiency. When using efficient forestry machinery, it is necessary to secure a sufficient amount of operation commensurate with the cost of machines, while simultaneously considering the feasibility of the labor force. However, no previous research has presented a quantitative forestry operation management method from the viewpoint of optimizing the amount of operation on a regional forestry scale. First, a basic model that mathematically quantifies the amount of operation and changes in forest biomass by applying system dynamics (SD) was developed, and a regional forestry scenario with the labor force as a constraint was optimized. As a result of the optimization, it is suggested that the scenario will be sustainable if regional forests are managed in an area of approximately 800 ha for 10 workers. The amount of operation in the scenario was generally feasible with a limited labor force during the simulation period and was also validated against reported domestic forestry data. We conclude that the SD model can contribute to the development of a regional forest management plan tailored to local conditions. In addition, it will greatly contribute to the assessment of carbon reduction in the national forestry sector through sustainable management of local forest biomass resources.

Assessing and Mapping Forest Functions through a GIS-Based, Multi-Criteria Approach as a Participative Planning Tool: An Application Analysis

A relatively new planning tool in Italy is the Local Forest Plan, which stands at a broader level in the land planning scale compared to the Forest Management Plan but at a finer scale considering a Regional or even National Forest Plan. This intermediate scale was considered the most appropriate for working out a planning process based on a multi-criteria assessment of forest functions. The proper functioning of forest ecosystems can provide services conceived as benefits people can obtain through ecological processes that sustain and satisfy essential needs of human life. Four particular forest functions providing services were identified: protective, productive, naturalistic and touristic, respectively. A set of functional criteria, as well as attributes within criteria, were recognized to perform an “Analytic Hierarchy Process” (AHP). A specific application of this methodological approach was selected as a case study. This multi-criteria decision-making process involved the participation of five selected experts in a preliminary phase, followed by the participation of thirty representative stakeholders who contributed to the forest planning process and the subsequent selection of actions to be taken. Data related to forest types and management, physical and morphological features of the forested terrain and infrastructure such as forest roads, touristic trails and hiking pathways, together with natural protected areas or wildlife preservation areas, were explicitly located in space by using a “geographical information service” (GIS) software. The combined application of AHP and GIS can be considered as a significant methodological innovation presented in the case study, together with the implementation of a participative process aimed at the management of forest resources and the creation of possible new professional and entrepreneurial forest activities for the benefit of the entire residential community.

Plant blindness represents the loss of generational knowledge and cultural identity

AbstractPlant blindness, the inability of people to notice plants, is of current interest in the natural sciences community. It has been hypothesized that communities of varying cultures may have improved plant sight. Researchers used an online survey to assess citizens ability to identify plants. The survey also intended to address the concern of elders from the Turtle Mountain Band of Chippewa Indians (TMBCI) who have seen reduced abundance of traditional plant species. The survey assessed knowledge of local wetland, grassland, and forest habitats; names of plants; and how citizens use plant features in identification. The survey gathered demographic data to determine trends across different demographic groups including age and ethnicity. A total of 216 participants took the survey, the majority classified themselves as female and Native American or Alaska Native. Our findings indicated that participants were able to identify forest and wetland plants the best, but struggled with grassland plants. Older individuals were more able to identify plants when compared to younger individuals. Ecologically, increasing plant knowledge is vital to rebuilding and maintaining the diversity of local habitats, but culturally the impacts are just as important. The practice of using traditional plants in medicine and ceremony is an integral part of the TMBCI culture. As both the knowledge and the plants disappear in younger generations, so does their unique cultural identity.

Effect of Fibre Orientation on the Bond Properties of Softwood and Hardwood Interfaces

Increasing concerns regarding carbon emissions and climate change are prompting a shift toward the use of sustainable materials in the construction industry. Engineered timber products are gaining attention in the construction industry due to advancements in lamination techniques and adhesives as well as the renewable characteristics of wood. Bond properties play a significant role in engineered timber products. In Australia, Radiata Pine (RP, softwood) and Shining Gum (SG, hardwood) share a large proportion of local and native plantation forest resources. The present paper investigates the bond behaviours of Australian softwoods (RP–RP), hardwoods (SG–SG) and hybrid-wood (RP–SG) combinations in both parallel (PAL) and perpendicular (PER) bonding directions using one-component polyurethane adhesives. The results indicate that most of the softwood samples were subjected to wood-side (timber) failure, whereas hardwood samples failed due to delamination but exhibited higher strength and stiffness regardless of bond direction. In contrast, bond direction had a significant effect on the bond characteristics of hybrid configurations. Improved bond properties were observed when bonded in PAL directions; however, negative effects were seen when bonded in PER directions. Obtained characteristic (5th percentile) shear bond strengths for RP–RP–PAL, RP–SG–PAL and SG–SG–PAL samples were 3.88 MPa, 6.19 MPa and 8.34 MPa, whilst those for RP–RP–PER, RP–SG–PER and SG–SG–PER samples were 3.45 MPa, 2.96 MPa and 7.83 MPa, respectively.

Urchin Gonad Response to Kelp Forest Restoration on the Palos Verdes Peninsula, California

Along the Palos Verdes Peninsula in southern California, high densities of Strongylocentrotus purpuratus (purple sea urchin) have consumed almost all macroalgae on large expanses (61 ha) of rocky reef habitat, creating “urchin barrens.” Mesocentrotus franciscanus (red sea urchin) harvesting comprises an important fishery in the region, as their gonads are sold as a high-value sushi product called “uni.” However, with a lack of macroalgal food resources, urchins in barrens are smaller and exist in a starved state, meaning little, if any, gonad product is available to the fishery. To restore local kelp forests and increase gonad biomass available to the M. franciscanus fishery, beginning in October 2013, S. purpuratus were culled in barrens to a target density of 2 per m2 across 5.2 ha of rocky reef on the Palos Verdes Peninsula. Mesocentrotus franciscanus were collected from urchin barren, restoration, and kelp reference sites from April to November 2014 to compare differences in gonad production among the three site types. Culling S. purpuratus resulted in the recovery of normal seasonal M. franciscanus gonad production throughout the 8-month study. Mesocentrotus franciscanus gonad weights at a given test diameter length in restoration sites were equivalent to, and sometimes exceeded, the gonad production of those from the kelp reference sites. The urchin test length distributions of collected M. franciscanus were consistently smaller at urchin barren sites than at kelp reference sites, while those in restoration sites generally fell in between.

Preface: Listen to the voices of local beech forests: An ecological and evolutionary conception of beech under phylogenetic and environmental constraints

AbstractBeech has long been the subject of ecological research in many fields. Recent studies using new methods are now being conducted. This special feature focuses on local beech forests and offers a collection of articles to readers of Ecological Research.

Issue Information

Ecological ResearchVolume 38, Issue 2 p. 211-213 ISSUE INFORMATIONFree Access Issue Information First published: 23 March 2023 https://doi.org/10.1111/1440-1703.12328AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume38, Issue2Listen to the voices of local beech forests: An ecological and evolutionary conception of beech under phylogenetic and environmental constraintsMarch 2023Pages 211-213 RelatedInformation

Modeling Climate Change Effects on the Distribution of Oak Forests with Machine Learning

The present study models the effect of climate change on the distribution of Persian oak (Quercus brantii Lindl.) in the Zagros forests, located in the west of Iran. The modeling is conducted under the current and future climatic conditions by fitting the machine learning method of the Bayesian additive regression tree (BART). For the anticipation of the potential habitats for the Persian oak, two general circulation models (GCMs) of CCSM4 and HADGEM2-ES under the representative concentration pathways (RCPs) of 2.6 and 8.5 for 2050 and 2070 are used. The mean temperature (MT) of the wettest quarter (bio8), solar radiation, slope and precipitation of the wettest month (bio13) are respectively reported as the most important variables in the modeling. The results indicate that the suitable habitat of Persian oak will significantly decrease in the future under both climate change scenarios as much as 75.06% by 2070. The proposed study brings insight into the current condition and further projects the future conditions of the local forests for proper management and protection of endangered ecosystems.

Radial Growth Response of Siberian Pines to Climate Warming in the Sayan Mountains, Southern Siberia, Russian Federation

Climate warming and subsequent drought are predicted to alter local forest production and carbon budgets, the sensitivity of which may be site- and species-specific. Although a warmer and drier climate often constrains tree growth, whether trees grown in cool, wet regions across the Siberian forest can in turn be promoted remains unknown. Here, we aimed to investigate the historical growth tendency of Siberian forests in the Sayan Mountain areas and to explore how climate interacts to regulate their growth. We used ring-width data from Siberian pine (Pinus sibirica Du Tour) sampled from three sites in this area to establish a regional chronology and calculate percentage growth change (%GC) over the past 250 years. Bootstrapped correlation analysis between the regional ring-width chronology and climatic factors indicates the mean air temperature, though not precipitation, is more often positively linked to the radial growth of Siberian pines. The %GC series shows that, from 1966 to 2006, the rising temperatures in May resulted in a significant increase in the radial-growth rate of Siberian pines (r = 0.47, p < 0.05). Our study suggests that the positive growth rate anomaly is more likely to occur as temperatures rise in Southern Siberia.

More warm‐adapted species in soil seed banks than in herb layer plant communities across Europe

Abstract Responses to climate change have often been found to lag behind the rate of warming that has occurred. In addition to dispersal limitation potentially restricting spread at leading range margins, the persistence of species in new and unsuitable conditions is thought to be responsible for apparent time‐lags. Soil seed banks can allow plant communities to temporarily buffer unsuitable environmental conditions, but their potential to slow responses to long‐term climate change is largely unknown. As local forest cover can also buffer the effects of a warming climate, it is important to understand how seed banks might interact with land cover to mediate community responses to climate change. We first related species‐level seed bank persistence and distribution‐derived climatic niches for 840 plant species. We then used a database of plant community data from grasslands, forests and intermediate successional habitats from across Europe to investigate relationships between seed banks and their corresponding herb layers in 2763 plots in the context of climate and land cover. We found that species from warmer climates and with broader distributions are more likely to have a higher seed bank persistence, resulting in seed banks that are composed of species with warmer and broader climatic distributions than their corresponding herb layers. This was consistent across our climatic extent, with larger differences (seed banks from even warmer climates relative to vegetation) found in grasslands. Synthesis. Seed banks have been shown to buffer plant communities through periods of environmental variability, and in a period of climate change might be expected to contain species reflecting past, cooler conditions. Here, we show that persistent seed banks often contain species with relatively warm climatic niches and those with wide climatic ranges. Although these patterns may not be primarily driven by species' climatic adaptations, the prominence of such species in seed banks might still facilitate climate‐driven community shifts. Additionally, seed banks may be related to ongoing trends regarding the spread of widespread generalist species into natural habitats, while cool‐associated species may be at risk from both short‐ and long‐term climatic variability and change.

Rethinking “Streetline Forestscapes” in a Broader Context of Urban Forestry: In-Between Ecological Services and Landscape Design, with Some Evidence from Rome, Italy

Urban forestry development plans, which sometimes pass under the “slogan” of urban forestry, are a great opportunity for our cities. Improving urban forestscapes is a successful part of any urban sustainability strategy, including concrete actions in support of citizens’ well-being. The experience of Italy with the most recent forest planning legislation and a specific focus on Rome, with the recent implementation of a local forest plan, is thus fundamental to give due weight to the different roles of road trees in the ecological, architectural, engineering and social fields, differentially considering some aspects relevant to urban forestation plans and in particular in projects for the new planting of road trees. The present study discusses the main issue of road trees as a part of the green system, linking the “porosity” of urban landscapes with beneficial contributions in terms of ecosystem services. It is outlined how considering the issue of road trees within the more general question of the structure of urban and metropolitan green areas, which includes urban parks, ecological corridors between wilderness areas, residual green areas of buildings, riparian strips of rivers, agricultural areas, natural and wooded areas, is necessary in current planning for urban forests. The project of new plantings and replacement of existing trees should also follow a careful analysis of the local and regional ecological network, promoting a full integration with the mobility network, the service system and the city’s public spaces, including vacant land. Any strategy promoted by urban forestry, and in particular tree-lined roads, should work in synergy with the other measures for urban redevelopment and landscape enhancement of the city in a truly holistic perspective. Finally, the identity of street tree lines in building the image of a given city should be significantly enhanced, recovering in some ways (and giving value to) the aesthetic and scenic role of urban trees.

Estimation of the Aboveground Carbon Stock in Kanonge Local Forest of Kaputa District in Northern Province, Zambia

Purpose: The majority of district-level carbon stock estimates for the local forests are obsolete and incomplete. Because of this, decisions made by policymakers have an impact on forest regions. This study establishes some baseline information for estimates of the above-ground carbon stocks in the nearby Kanonge forest.
 Methodology: The use of a sequential explanatory design allowed the quantitative data to be collected and analysed first, and the qualitative data to be collected and analysed later to explain why the variables identified in the first phase are significant predictors of the aboveground carbon stocks. As a result, 15 sample plots were used in the forest, 286 households were sampled on villages within 5km radius to the forest, 8 key informants were sampled from Forestry Department, 8 from Ministry of Agriculture, 10 village head persons and 10 forest users. The quantitative data was collected using forest inventories and household surveys while qualitative data was collected using key informants’ interviews. The allometric equations were used to analyse forest inventory data, logistic regression was used to analyse household survey data and the key informant interviews were analysed using thematic analysis.
 Findings: The results show that, the above ground biomass and carbon stock were 276.19 ± 7.41 and 155.76 ± 4.18 t ha-1 respectively. The logistic regression results shows that Forest products use, farm size, household size and forest clearing where the significant predictors of the reduction of the aboveground carbon stocks. The results further reveals that there is inadequate intersectoral coordination at district and local level.
 Unique Contribution to Theory, Practice and Policy: Further study should be done to find strategies to sustain carbon stocks in the forest while maintaining the use of the forest by the local communities. This study provides accurate estimates of forest and tree carbon stocks and supports in the development of the district integrated plan in accordance with decentralized policy. This information can therefore be used at the district and federal levels in various carbon programs like REDD+, offering the district the chance to participate in the fight against climate change and global warming.

Polycyclic aromatic hydrocarbons in a Natural Heritage Estuary influenced by anthropogenic activities in the South Atlantic: Integrating multiple source apportionment approaches

Polycyclic aromatic hydrocarbons (PAHs) were analysed in the sediments of one of the most well-preserved estuaries in South Brazil, the Paranaguá Estuarine System (PES), using several source apportionment tools. The ∑PAH ranged from < DL to 125.6 ng g−1 dw (dry weight) (average 29.9 ± 26.1 ng g−1 dw), and the lowest levels detected were similar to those found in other protected areas of the world. In general, the PAH concentrations indicated excellent environmental quality for the entire estuary. Principal component analysis indicated that fine sediments and total organic carbon were the main factors controlling PAH concentrations in the PES. Multiple PAH sources were identified in the study area; biomass burning and fossil fuel combustion predominated but considerable amounts of petrogenic residues were also observed. We identified evidence of a contribution from an adjacent watershed resulting from the construction of interconnections between large rivers and from years of intense deforestation in the local Atlantic Forest.

Phase I Analysis of Nonlinear Profiles Using Anomaly Detection Techniques

In various industries, the process or product quality is evaluated by a functional relationship between a dependent variable y and one or a few input variables x, expressed as y=fx. This relationship is called a profile in the literature. Recently, profile monitoring has received a lot of research attention. In this study, we formulated profile monitoring as an anomaly-detection problem and proposed an outlier-detection procedure for phase I nonlinear profile analysis. The developed procedure consists of three key processes. First, we obtained smoothed nonlinear profiles using the spline smoothing method. Second, we proposed a method for estimating the proportion of outliers in the dataset. A distance-based decision function was developed to identify potential outliers and provide a rough estimate of the contamination rate. Finally, PCA was used as a dimensionality reduction method. An outlier-detection algorithm was then employed to identify outlying profiles based on the estimated contamination rate. The algorithms considered in this study included Local Outlier Factor (LOF), Elliptic Envelope (EE), and Isolation Forest (IF). The proposed procedure was evaluated using a nonlinear profile that has been studied by various researchers. We compared various competing methods based on commonly used metrics such as type I error, type II error, and F2 score. Based on the evaluation metrics, our experimental results indicate that the performance of the proposed method is better than other existing methods. When considering the smallest and hardest-to-detect variation, the LOF algorithm, with the contamination rate determined by the method proposed in this study, achieved type I errors, type II errors, and F2 scores of 0.049, 0.001, and 0.951, respectively, while the performance metrics of the current best method were 0.081, 0.015, and 0.899, respectively.