Semi-natural Forested Landscape under a Bark Beetle Outbreak: A case study of the Bohemian Forest (Czech Republic)

Long-term and lasting human interference in forest ecosystems in the Bohemian Forest has resulted in the loss of some equilibrium mechanisms and hence increased susceptibility to ecological disturbances. Two methods for estimating bark beetle outbreaks in spruce forests are reported: an assessment of the susceptibility of individual trees to attack according to crown structure characteristics; and the use of remotely sensed data and image processing techniques to quantify changes in forest cover. The results document a significant increase in the area of highly damaged and dead forest classes, from 1% in 1987 to 16% in 1998, and a decrease in the area of healthy and moderately damaged spruce classes from 71% in 1987 to 52% in 1998. A possible approach to managing mountain Norway spruce ecosystems invaded by bark beetle in the Bohemian Forest is proposed.     

Spatial and temporal dynamics of land use pattern in Turkey: A case study in İnegöl

Recognition and understanding of landscape dynamics as a historical legacy of disturbances are necessary for sustainable management of forest ecosystems. This study analyzed forest dynamics and spatial–temporal changes in land use/land cover pattern in a sub-temperate like alluvial forest land with 1778 km² area along the Eagan Sea coast of Turkey (İnegöl). This area is studied by comparing Landsat images from 1987 to 2001 and evaluated with spatial analyses of forest cover type maps from 1972, 1983, 1993 to 2004 using GIS. The study investigated temporal changes of spatial structure of forest conditions over the period using Fragstats™.The results showed that the forested areas increased both in between 1972 and 1993 years (3.3%) and between 1987 and 2001 years (6.7%). In terms of spatial configuration, İnegöl forests are generally fragmented in the latter periods due to intensive forest utilization, illegal use, expansion of settlements and infrastructural development in the lowlands. Land use pattern significantly changed over time depending on a few factors such as unregulated management actions, social pressure and demographic movements. In conclusion, land use changes have developed in favor of forestry over time between 1972–1993 and 1987–2001. The study revealed that demographic movements have a minor effect on landscape dynamics. Both spatial and temporal changes and the factors affecting these changes should be determined for developing sustainable management of forest resources.     

Rare and unique communities in the South of Western Siberia of the Bolshaya Sogra natural complex (Kislukhinsky state natural regional reserve,the Altaisky Krai,Russia)

The paper presents floristic and geo-botanical characteristics of rare forest ecosystems of the south of Western Siberia – spruce forests on the site of the Ob river ancient bed within the modern Bolshaya Sogra within the boundaries of the state natural reserve ‘Kislukhinsky’ (Altai region). Spruce forests here are at the edge of their spread in the West Siberian Plain conditions. There are over 300 species of vascular plants found in these spruce forests. Among them are plants that are typical of the mountain taiga associations of Russian Altai, as well as orchids, which have high species diversity. Spruce forest set of associations is also varied. The uniqueness of the described communities to the south of Western Siberia, the large number of rare and endangered plant species listed in the Red Books of different ranks, as well as the boreal forest species complex rare to the lowland wooded steppe, which has a relict character, all served as the basis for allocating a special protection area in the ‘Kislukhinsky’ reserve and attributing the studied spruce forests to the forests of high conservation value.     

Spatiotemporal reconstruction of lead contamination using tree rings and organic soil layers

An atmospheric dispersion model predicting ground-level concentrations from a point source of metal emissions (Murdochville smelter) was calibrated on tree rings in black spruce (Picea mariana Mill. B.S.P.) in order to reconstruct the spatial and temporal Pb-contamination pattern in the Gaspé Peninsula (Canada). Model predictions were validated with forest-floor Pb concentrations that resulted from accumulation of this element over the years and that provide a robust spatial-deposition pattern. Atmospheric emission records were also used to verify the good agreement between the smelter emissions and the temporal-information pattern present in tree rings. Tree rings that formed during the period of smelter emissions exhibited Pb concentrations that correlated with those measured in humus. Temporal variability in tree-ring concentrations was closely associated with the smelter emissions, suggesting that black spruce trees were able to record Pb pollution from a point source. However, a time gap of at least 15years must be considered between the emissions and the actual uptake and incorporation of Pb in the tree rings. A decrease in the level of contamination in the area was associated with the decrease in smelting activities, suggesting a natural resilience of the forest ecosystems to the contamination. This study highlights the strong potential for combining dendrochemical, soil, and modeling approaches in environmental research.     

Biogeochemical dynamics following land use change from forest to pasture in a humid tropical area (Rondĵnia, Brazil): a multi-element approach by means of XRF-spectroscopy

Forest burning for pastures in tropical areas represents an important component of biogeochemical cycles. In order to provide information concerning chemical modifications after forest burning, in this local study the total contents of 29 elements in topsoils were analyzed when forest is changed to pasture land. The work was carried out in 1999 in Rond?nia state (Brazilian Amazon Basin) focussing on a native forest site and four neighboring pastures established in 1987, 1983, 1972 and 1911 after forest conversion. Chemical fingerprint graphs of the pasture soils related to the forest soil illustrated mainly higher contents for the vast majority of macro- and micro nutrients, but for other elements as well (e.g. Ba, Sr, Cr, Ni, V or Pb). Also increases of pH levels were measured in all pastures, which remained higher than the forest values for decades. After initial increases of most of the elements in pasture of 1987 the decreases of some macro elements (e.g. C, N, K, Mg, S) in pasture 1983 as well as again the enhanced levels in pasture 1972 and 1911 suggest both a persistent leaching of these elements and a function of pasture age where external element inputs exceed outputs. Ash deposition, accumulation of organic matter, animal excreta as well as natural soil conditions are discussed as influencing factors on the element contents of the original forest and the pasture soils. Nevertheless, in this particular area continuous pasturing after forest clearing primarily enriched the soils in elements.     

Trajectory Analysis of Forest Cover Change in the Tropical Dry Forest of Burkina Faso,West Africa

Forest cover decline is one of the most important environmental issues in the tropics. The present study was carried out in Burkina Faso, West Africa, and aimed at assessing the trajectories of forest cover change and measuring landscape metrics of the trajectory classes in order to better understand the processes of change. Landsat and ASTER images acquired over a period of 30 years were used for cover change detection and the Fragstats package was used to compute landscape metrics with five unifying change classes. Results showed a substantial increase in cropland with concurrent decline in forest cover. Deforestation represented 63% of the Percentage of Landscape (PLAND) in 2006, while reforestation accounted for only 28%. Both of these classes had high Normalized Landscape Shape Index (NLSI) values, indicating that they were present as scattered small patches. The old cultivation (30-year permanent cropland) was aggregated (IJI ≈ 0) while deforestation exhibited highly interspersed patches. The old forest and old cultivation presented lower Area Weighted Fractal Dimension Index (FRAC_AM), but deforestation and reforestation had the higher FRAC_AM. These results confirmed that there was a high level of deforestation and fragmentation in southern Burkina Faso and justify the need for a proper management plan to ensure the sustainable use of forest resources.     

Evaluation of an ecological land type classification system, Natchez Trace State Forest, western Tennessee, USA

In an effort to aid future research and forest management decisions, we incorporated data on forest type, soils and topography into a geographic information systems (GIS)-based ecological land classification system for Natchez Trace State Forest (NTSF) in western Tennessee. The area is still recovering from the effects of cultivation, logging, forest clearing and grazing during the 1800s and early 1900s, but the data indicated that most stands now contain sawtimber-sized trees after more than 50 years of secondary succession. Our analyses showed that forest types were not randomly associated with soil characteristics or topography. For example, the most heavily gullied lands were strongly associated with pine forests while hardwoods were more associated with upland soils and certain types of sideslopes. Mature hardwood stands, which were deemed to be of the greatest conservation value, were classified into eight ecological land types based on soil type, aspect, orientation and topographic setting for further study. When these land types were evaluated with respect to data on forest composition and environmental conditions collected in the field, we found that the variables used to derive the eight classes were important in influencing floristic patterns. It was, however, clear that the classes themselves imperfectly captured patterns of overstory community composition for a number of reasons. Thus, while land types provide a potentially valuable management tool, their utility and successful implementation are dependent upon a recognition of their inherent limitations.     

Spectral analysis of coniferous foliage and possible links to soil chemistry: are spectral chlorophyll indices related to forest floor dissolved organic C and N?

Dissolved organic matter in soils can be predicted from forest floor C:N ratio, which in turn is related to foliar chemistry. Little is known about the linkages between foliar constituents such as chlorophylls, lignin, and cellulose and the concentrations of water-extractable forest floor dissolved organic carbon and dissolved organic nitrogen. Lignin and cellulose are not mobile in foliage and thus may be indicative of growing conditions during prior years, while chlorophylls respond more rapidly to the current physiological status of a tree and reflect nutrient availability. The aim of this study was to examine potential links among spectral foliar data, and the organic C and N of forest soils. Two coniferous species (red spruce and balsam fir) were studied in the White Mountains of New Hampshire, USA. Six trees of each species were sampled at 5 watersheds (2 in the Hubbard Brook Experimental Forest, 3 in the Bartlett Experimental Forest). We hypothesized that in a coniferous forest, chemistry of old foliage would better predict the chemical composition of the forest floor litter layer than younger foliage, which is the more physiologically active and the most likely to be captured by remote sensing of the canopy. Contrary to our expectations, chlorophyll concentration of young needles proved to be most tightly linked to soil properties, in particular water-extractable dissolved organic carbon. Spectral indices related to the chlorophyll content of needles could be used to predict variation in forest floor dissolved organic carbon and dissolved organic nitrogen. Strong correlations were found between optical spectral indices based on chlorophyll absorption and forest floor dissolved organic carbon, with higher foliage chlorophyll content corresponding to lower forest floor dissolved organic carbon. The mechanisms behind these correlations are uncertain and need further investigation. However, the direction of the linkage from soil to tree via nutrient availability is hypothesized based on negative correlations found between foliar N and forest floor dissolved organic carbon.     

Relating surface fire spread to landscape structure: An application of FARSITE in a managed forest landscape

Recent studies suggest that manipulation of landscape patterns is the most preferred method to reduce susceptibility of landscape to fire spread. We evaluated the effects of landscape spatial pattern and spatial heterogeneity of fuel loading on surface fire spread using the FARSITE model in Chequamegon National Forest landscape, Wisconsin. Five forest management scenarios were developed to generate different landscape spatial patterns with unique fuel loading distribution. For each management scenario, 16 fires were simulated. We found that altered landscape spatial pattern and spatial heterogeneity of fuel loading interactively influenced fire spread. Moreover, we revealed that numerous, irregular-shaped, and different types of patches reduced fire spread. Among tested indices of landscape spatial pattern, patchy density, mean patch shape, patch shape standard deviation, area weighted mean shape index (AWMSI) and Shannon's diversity index were meaningful for predicting fire spread. However, the effect of landscape spatial pattern on fire spread decreased as fuel loading became more spatially heterogeneous. We also found that the effect of landscape spatial pattern on fire spread became insignificant when AWMSI was less than 4.33. Our results suggested that a forest management plan would need to consider the number, shape, size and type of forest patches for regulating fire spread.     

Relationships between urbanization and the oak resource of the Minneapolis/St. Paul Metropolitan area from 1991 to 1998

Urbanization was associated with loss and transformation of the oak forest in the Twin Cities (Minneapolis and St. Paul) metropolitan area (TCMA) over a recent 7-year interval. Between 1991 and 1998, urbanization increased based on several indicators: population density, area of developed land, and area of impervious surface—total impervious area and area within three classes of increasing degree of imperviousness (protected, affected, and degraded). We quantified relationships between changes in urbanization and changes in several parameters describing the oak forest at the scale of ecological subsection. Increased total and affected impervious area were strongly correlated with decreased area of oak forest when changes of the urbanization indicators and oak were expressed as percentages of the subsection area. Relationships were reversed when changes were expressed as percentages of the 1991 values. Increased population density was strongly correlated with increased loss in numbers and increased isolation of oak patches, but weakly correlated with loss of oak forest area. This is the first study to quantify relationships between changes in urbanization and changes in a specific forest cover type. Our results demonstrate complexities of urbanization impacts on a metropolitan forest resource, and highlight the importance of selected variables, spatial and temporal scales, and expressions of change when quantifying these relationships.     

基于GPS数据与空间统计的城市森林公园 景观偏好研究

城市森林公园拥有良好的自然资源,能承载各种游憩活动,为市民带来多种益处。以上海共青森林公园与炮台湾森林公园为例,利用GPS设备每隔10s采集一次游客的地理坐标位置,并应用栅格密度、标准差椭圆与热点识别3种空间统计方法分析相关空间位置点,识别受游客喜爱的游憩场地与景观空间类型。结果表明:游客在2个森林公园中的分布并不均匀,共青森林公园西部与炮台湾森林公园南部吸引了大量游客;最吸引游客停留的区域包括儿童游乐设施区、广场、大草坪、烧烤区和滨江区域。最后,根据分析结果,对森林公园的规划设计与管理提出了相应建议。     

基于改进YOLOv3 的无人机林火监测系统设计与实现

以无人机为飞行平台，基于目标检测技术设计并实现了一套林火监测系统，针对原生态YOLOv3 算法在烟雾与火焰检测时表现不佳，从增加NMS 和重新聚类Anchors 两个方面对算法进行改进，检测准确率和召回率分别提高了6.8% 、11.92%。该系统无论昼夜都可实时监测森林火灾，提高了森林防火安全防范的能力和林火预警的自动化、数字化水平。     

A comparative study on machine learning modeling for mass movement susceptibility mapping (a case study of Iran)

Mass movements are among the most dangerous natural hazards in mountainous regions. The present study employs machine learning (ML) models for mass movement susceptibility mapping (MMSM) in Iran based on a comprehensive dataset of 864 mass movements which include debris flow, landslide, and rockfall during the last 42 years (1977–2019) as well as 12 conditional factors. The results of validation stage show that RF (random forest) is the most viable model for mass movement susceptibility maps. In addition, MARS (multivariate adaptive regression splines), MDA (mixture discriminant additive), and BRT (boosted regression trees) models also provide relatively accurate results. Results of the AUC for validation of produced maps were 0.968, 0.845, 0.828, and 0.765 for RF, MARS, MDA, and BRT, respectively. Based on MMSM generated by RF model, 32% of study area is identified to be under high and very high susceptibility classes. Most of the endangered areas for mass movement are in the west and central parts of the Chaharmahal and Bakhtiari Province. In addition, our findings indicate that elevation, slope angle, distance from roads, and distance from faults are critical factors for mass movement. Our results provide a perspective view for decision makers to mitigate natural hazards.

     

长白山地区常见阔叶树种有机质燃烧特性研究

摘 要：采集长白山地区7种常见阔叶树种叶片、树皮,通过热重分析仪测定燃点、碳化阶段开始温度、热值和灰分等,应用TOPSIS 分析法对树种热稳定性进行评价。根据实验结果,参数化了叶片、树皮有机质燃烧过程数学模型,用来研究叶片和树皮2类有机质燃烧过程质量损失和释放热量,得出7个阔叶树种热稳定性排序,山杨、大青杨、水曲柳、紫椴、核桃楸、黄波罗、蒙古栎热稳定性依次减弱。长白山常见7个阔叶树种有机质燃烧过程中叶片燃烧释放的热量更具持续性、树皮燃烧强度大,2类预测模型有效解释了长白山地区常见阔叶树种热稳定性。在长白山地区低质低效林、防火林带改造过程中,可优选热稳定性强的树种进行森林更新,为制定长白山地区森林防火减灾对策和有关部门战略决策提供参考。     

Pb and 206Pb/207Pb isotopic analysis of a tree bark pocket near Sheffield,UK recording historical change in airborne pollution during the 20th century

A section of tree trunk (beech, Fagus sylvatica) containing a bark pocket progressively enclosed at the junction of two branches was collected from a semi-rural location near Sheffield, UK. According to the annual growth rings, the bark pocket formed between ca. 1919 and 1998 (the date of felling). The bark pocket was divided into consecutive samples of differing radial depth (and thus age), that were analysed by ICP mass spectrometry. The Pb concentration varied from 7 to 78 mg kg (-1) and the 206Pb/207Pb isotope ratio from 1.11 to 1.15. In contrast, the current surface bark contained 46 mg kg(-1) Pb and recorded a 206Pb/207Pb ratio of 1.11. The changing elemental and isotopic composition of the bark pocket recorded historical change in the level and sources of airborne Pb pollution. An overall increase in Pb concentration with time was accompanied by a progressive reduction in 206Pb/207Pb from ca. 1935 to 1943. Mass balance calculations indicated that Pb additives in petrol contributed significantly to the rise in concentration, accounting for a maximum of 50% of the total Pb for ca. 1986-1998, but that other sources were generally dominant. The highest Pb concentrations were recorded from ca. 1951 to 1973, suggesting a high level of industrial pollution. A reduction in Pb concentration and reversal of the trend in 206Pb/207Pb was observed in the current bark.     

Retrospective determination of 137Cs specific activity distribution in spruce bark and bark aggregated transfer factor in forests on the scale of the Czech Republic ten years after the Chernobyl accident

The ¹³⁷Cs specific activities (mean 32 Bq kg⁻¹) were determined in spruce bark samples that had been collected at 192 sampling plots throughout the Czech Republic in 1995, and were related to the sampling year. The ¹³⁷Cs specific activities in spruce bark correlated significantly with the ¹³⁷Cs depositions in areas affected by different precipitation sums operating at the time of the Chernobyl fallout in 1986. The ratio of the ¹³⁷Cs specific activities in bark and of the ¹³⁷Cs deposition levels yielded bark aggregated transfer factor T_ag about 10.5 × 10⁻³ m⁻² kg⁻¹. Taking into account the residual specific activities of ¹³⁷Cs in bark 20 Bq kg⁻¹ and the available pre-Chernobyl data on the ¹³⁷Cs deposition loads on the soil surface in the Czech Republic, the real aggregated transfer factor after and before the Chernobyl fallout proved to be T*_ag = 3.3 × 10⁻³ m⁻² kg⁻¹ and T**_ag = 4.0 × 10⁻³ m⁻² kg⁻¹, respectively. The aggregated transfer factors T*_ag for ¹³⁷Cs and spruce bark did not differ significantly in areas unequally affected by the ¹³⁷Cs fallout in the Czech Republic in 1986, and the figures for these aggregated transfer factors were very similar to the mean bark T_ag values published from the extensively affected areas near Chernobyl. The magnitude of the ¹³⁷Cs aggregated transfer factors for spruce bark for the pre-Chernobyl and post-Chernobyl period in the Czech Republic was also very similar. The variability in spruce bark acidity caused by the operation of local anthropogenic air pollution sources did not significantly influence the accumulation and retention of ¹³⁷Cs in spruce bark. Increasing elevation of the bark sampling plots had a significant effect on raising the remaining ¹³⁷Cs specific activities in bark in areas affected by precipitation at the time when the plumes crossed, because the sums of this precipitation increased with elevation (covariable).     

Distribution of radiocaesium in an Austrian forest stand

Within an Austrian spruce stand, vertical distribution of radiocaesium in soil as well as 137Cs concentration in different forest ecosystem compartments including spruce and surface water were investigated 10 years after the Chernobyl accident. The total 137Cs inventory in the forest was estimated to be 46 kBq m-2 (ref. date: 86-05-01). From the collected data annual input rates via litterfall of 0.48% per year and output rates through waterflows of only 0.02% per year were derived. The results identify the high importance of forest soils as a sink for radiocaesium. The estimated ecological residence half-times turned out to be highest in the organic soil horizons (1-3 years per cm), whereas in mineral horizons the values decrease significantly. As a consequence, soil inventory represents more than 95% of the total, whereas only approximately 3.3% of the 137Cs inventory is stored in the living biomass of spruce trees and a further 0.5% in the phytomass of understorey vegetation.     

Elemental analyses of pine bark and wood in an environmental study

Bark and wood samples were taken from the same individuals of Scots pine (Pinus sylvestris L.) from a polluted area close to a Cu-Ni smelter in Harjavalta and from some relatively unpolluted areas in western Finland. The samples were analysed by thick-target particle induced X-ray emission (PIXE) after preconcentration by dry ashing at 550 degrees C. The elemental contents of pine bark and wood were compared to study the impact of heavy metal pollution on pine trees. By comparison of the elemental contents in ashes of bark and wood, a normalisation was obtained. For the relatively clean areas, the ratios of the concentration in bark ash to the concentration in wood ash for different elements were close to 1. This means that the ashes of Scots Pine wood and bark have quite similar elemental composition. For the samples from the polluted area the mean concentration ratios for some heavy metals were elevated (13-28), reflecting the effect of direct atmospheric contamination. The metal contents in the ashes of pine bark and wood were also compared to recommendations for ashes to be recycled back to the forest environment. Bark from areas close to emission sources of heavy metal pollution should be considered with caution if aiming at recycling the ash. Burning of bark fuel of pine grown within 6 km of the Cu-Ni smelter is shown to generate ashes with high levels of Cu, Ni as well as Cd, As and Pb.     

为下一代作准备:林后四林平地森林园区规划

林后四林平地森林园区是一处集平地造林、在地文化、栖地营造、资源利用与环境教育为一体的学习园区.在其不断的发展下,现成为大武山低海拔自然森林园区,作为生态栖地修复、区域文化体验及休闲游憩的场域.从环境修复的角度保有农垦地和草生地生态环境,并营造大武山低海拔森林的栖地环境,提供猛禽、鸟类及两栖类动物栖息繁衍之地.重视生态保育意义的同时,发挥环境教育和生态旅游的价值.因气候环境变迁,以分散排水、贮流、自然人渗及自然过滤方式为主,同时进行土壤地利改良,达到环境保全修复的功效.以现地环境保育及生态演变历史延续对自然环境的关怀,营造合宜的生态栖地、掌握水资源的保存与再利用,为下一代的自然生态环境作准备.     

An analysis of tree mortality in southern California using high spatial resolution remotely sensed spectral radiances: a climatic change scenario

The value of remotely sensed data for ecological monitoring and modeling studies that address landscape changes due to climatic change is widely recognized. However, these data can be collected at a variety of spatial resolutions which was significant implications in terms of the information that can be derived from the data. Most readily available remotely sensed data tend to have ground resolutions substantially greater than the size of individual plants so pixels may contain a mixture of vegetation types, background cover, illumination intensity and shadow. These mixtures make it difficult to evaluate fine-scale vegetation dynamics. This paper examines the potential utility of high spatial resolution remotely sensed data for assessing vegetation condition within a climatic change context. The drought in southern California that started in 1987 and the associated increase in tree mortality due to bark beetle infestations, provided the climatic change scenario for the study. A possible consequence of anthropogenically induced climatic change is the occurrence of more intense and prolonged droughts in some regions leading to greater mortality rates for susceptible vegetation species. Studies of present-day patterns and processes of vegetation mortality associated with droughts may help to identify future consequences of hypothesized climatic changes. High spatial resolution (0.5 m) reflected spectral radiances were collected over the Cuyamaca State Park in southern California and related to levels of bark beetle infestations that increased during the drought years. The results from this demonstration project indicated that high spatial resolution remotely sensed data allow investigators to isolate individual plants from the scene background and are likely to provide valuable information for assessing vegetation condition. The characteristics of the reflected spectral radiances and their geostatistical properties may be potential indicators of differences in vegetation condition. These data are also likely to be valuable for determining biophysical quantities required in models of ecosystem function and for monitoring key species that may be particularly sensitive to climatic change (indicator species).