Detecting the presence of natural forests using airborne laser scanning data

Centuries of forest exploitation have caused significant loss of natural forests in Europe,leading to a decline in populations for many species.To prevent further loss in biodiversity,the Norwegian government has set a target of protecting 10%of the forested area.However,recent data from the National Forest Inventory(NFI)reveals that less than 2%of Norway's forested area consists of natural forests.To identify forests with high conservation value,we used vertical and horizontal variables derived from airborne laser scanning(ALS)data,along with NFI plot measurements.Our study aimed to predict the presence of natural forests across three counties in southeastern Norway,using three different definitions:pristine,near-natural,and semi-natural forests.Natural forests are scarce,and their underrepresentation in field reference data can compromise the accuracy of the predictions.To address this,we assessed the potential gain of including additional field data specifically targeting natural forests to achieve a better balance in the dataset.Additionally,we examined the impact of stratifying the data by dominant tree species on the performance of the models.Our results revealed that semi-natural forests were the most accurately predicted,followed by near-natural and pristine forests,with Matthews correlation coefficient values of 0.32,0.24,and 0.17,respectively.Including additional field data did not improve the predictions.However,stratification by species improved the accuracy of predictions for near-natural and semi-natural forests,while reducing accuracy for pristine forests.The use of horizontal variables did not improve the predictions.Our study demonstrates the potential of ALS data in identifying forests with high conservation value.It provides a basis for further research on the use of ALS data for the detection and conservation of natural forests,offering valuable insights to guide future forest preservation efforts.

The Use of Mineral Nutrients for Biomass Production by Young Birch Stands and Stands Vitality in Different Forest Growing Conditions

The data of field studies about mineral nutrient content in the biomass components of young birch stands （9-15 years old） in different forest growing conditions and soil types have been analyzed. In forest growing conditions on fertile soils （ASG, TSC and SP） the total amount of biomass produced by young birch stands divides into fractions as follows： stem wood 51.8%-59.5%; branch wood 9.8%-12.4%; foliage 5.7%-6.8%; stump wood and roots 25%-30%. In forest types on lean soils （TP） the same indices are 32.3%-41.8%, 18.2%-24.2%, 13.2%-16.1% and 26.8%-27.4%, respectively. The stand performance closely correlates with the basic nutrient （P, N, K, C and Mg） availability in forest soils. In lean typicpodzol soils （TP） the content of mineral nutrients is no higher than 20%-48% of that in more fertile soils （ASG, TSC and SP）. In young birch stands the take-up of mineral nutrients from 0-40 cm soil layer for developing the above-ground biomass makes a fairly small proportion of the total： up to 4.8%-6.2% for P; 4.9%-12.2% for N; 1.1%-4.1% for K; 11.6% for Ca; 0.8%-7.7% for Mg; in leaner soils the same indices are P 0.1%-0.4%, N 1%-1.5%, K 0.2%-0.6%, Ca 0.1%-0.9%, Mg 0.1%-0.8%, respectively. The analyses of pest damages in young birch stands confirm a hypothesis that the degree of pest damage depends on the stand vitality as described by the site index.

Impact failure models and application condition of trees in debris-flow hazard mitigation

Forestry has played an important role in hazard mitigation associated with debris flows.Most forest mitigation measures refer to the experience of soil and water conservation,which disregard the destructive effect of debris flows,causing potentially serious consequences.Determination of the effect of a forest on reducing debris-flow velocity and even stopping debris flows requires distinguishing between when the debris flow will destroy the forest and when the trees will withstand the debris-flow impact force.In this paper,we summarized two impact failure models of a single tree: stem breakage and overturning.The influences of different tree sizes characteristics(stem base diameter,tree weight,and root failure radius) and debris-flow characteristics(density,velocity,flow depth,and boulder diameter) on tree failure were analyzed.The observations obtained from the model adopted in this study show that trees are more prone to stem breakage than overturning.With an increase in tree size,the ability to resist stem breakage and overturning increases.Debris-flow density influences the critical failure conditions of trees substantially less than the debrisflow velocity,depth,and boulder diameter.The application conditions of forests in debris-flow hazard mitigation were proposed based on the analysis of the model results.The proposed models were applied in the Xiajijiehaizi Gully as a case study,and the results explain the destruction of trees in the forest dispersing zone.This work provides references for implementing forest measures for debris-flow hazard mitigation.

Community Characteristics of Wild Fruit Forests Along Elevation Gradients and the Relationships Between the Wild Fruit Forests and Environments in the Keguqin Mountain Region ofⅠii

In this paper,the quantitative relationship between the wild fruit communities and direct environmental factors is discussed on the basis of detailed data on landscape scale habitats obtained through field vegetation investigation.The results from TWINSPAN and DCCA showed that:1) In the distribution sections of the wild fruit forest in the Keguqin Mountain region,the basic patterns characteristic of the different habitats are due to topographic factors,nutrients and moisture conditions;2) The elevation affected the most basic differentiation of plant communities in the study area,indicating that the elevation condition was the most important factor restricting the distribution of the wild fruit communities in the study area;3) The close relationship between the moisture content in the upper soil layer and the elevation reflected the influence of moisture conditions on both wild fruit and herb-layer communities;4) Nutrient differences not only indicated that the habitat conditions were different in themselves but also showed that the present nutrient conditions of the habitats were seriously affected by human activities.In summary,under complicated mountainous topographic conditions,the habitat conditions for the communities differed very significantly,and the combination of elevation,soil moisture content,total nitrogen,slope aspect,and pH value influenced and controlled the formation of community distribution patterns in the study area.

The dynamic response of forest vegetation to hydro- thermal conditions in the Funiu Mountains of western Henan Province

This paper uses HJ-1 satellite multi-spectral and multi-temporal data to extract forest vegetation information in the Funiu Mountain region. The S-G filtering algorithm was employed to reconstruct the MODIS EVI（Enhanced Vegetation Index） time-series data for the period of 2000–2013, and these data were correlated with air temperature and precipitation data to explore the responses of forest vegetation to hydrothermal conditions. The results showed that：（1） the Funiu Mountain region has relatively high and increasing forest coverage with an average EVI of 0.48 over the study period, and the EVI first shows a decreasing trend with increased elevation below 200 m, then an increasing trend from 200–1700 m, and finally a decreasing trend above 1700 m. However, obvious differences could be identified in the responses of different forest vegetation types to climate change. Broad-leaf deciduous forest, being the dominant forest type in the region, had the most significant EVI increase.（2） Temperature in the region showed an increasing trend over the 14 years of the study with an anomaly increasing rate of 0.27℃/10a; a fluctuating yet increasing trend could be identified for the precipitation anomaly percentage.（3） Among all vegetation types, the evergreen broad-leaf forest has the closest EVI-temperature correlation, whereas the mixed evergreen and deciduous forest has the weakest. Almost all forest types showed a weak negative EVI-precipitation correlation, except the mixed evergreen and deciduous forest with a weak positive correlation.（4） There is a slight delay in forest vegetation responses to air temperature and precipitation, with half a month only for limited areas of the mixed evergreen and deciduous forest.

基于孤立森林方法的单元式空调器异常检测

为了挖掘单元式空调器云端数据价值和提高售后运维效率,本文开发了一种可部署在云平台的设备运行异常检测方法。通过修正的仿真模型生成大量的正常和异常数据用于检测的模型训练和评估。为了提高模型的泛化能力,提出了排气过热度、冷凝器过冷度、吸气管过热度和压缩机压比等基于工程经验和物理意义的新特征。对孤立森林、基于角的离群点检测、基于聚类的局部离群因子、基于直方图的离群点检测和K近邻等模型进行了评估。结果表明,孤立森林方法检出率在25%以上,检出正确率在67%以上,检测效果最好,将训练好的孤立森林模型检测现有云平台数据,可成功检测出制冷剂泄漏的异常情况。

基于农田土壤镉污染修复后糙米镉的指标筛选

目前农田土壤镉污染修复以降低糙米镉含量为标准,而忽略了其变化的关键性的土壤物理、化学及生物指标。基于此,采用方差分析、多元回归分析、通径分析、随机森林和结构方程模型等统计方法分析了土壤pH值、有机质、容重、阳离子交换量、速效养分、质地、微团聚体、酶活性、微生物数量等23个土壤指标对土壤有效态Cd和糙米Cd含量重要性排序。结果表明,总体上施用土壤调理剂提高了土壤pH值、容重和阳离子交换量,改变了土壤质地组成,增加了大粒级团聚体,并影响了微生物环境,有效降低了土壤有效态Cd和糙米Cd含量,但抑制了部分酶活性和微生物数量。通过逐步回归分析,表明土壤pH值和放线菌可以解释土壤有效态Cd 64.32%的变化,阳离子交换量、速效钾、有效磷和蔗糖酶可以解释糙米Cd 82.10%的变化;通径分析表明大粒径团聚体、有机质、黏粒、砂粒、放线菌和真菌对土壤有效态Cd和糙米Cd的直接效应较大;随机森林分析表明土壤pH值是影响土壤有效态Cd和糙米Cd含量的主导因素;结构方程模型表明糙米Cd含量主要受土壤pH值、有机质、阳离子交换量和有效磷的影响,土壤有效态Cd主要受土壤酶活性和微生物数量的影响。不同分析方法侧重点不同,总体上对糙米Cd含量影响较大的是pH值、阳离子交换量、有效磷和有机质等,对土壤有效态Cd含量影响较大的是pH值、放线菌和有机质等。