Mapping the urban forest in detail: From LiDAR point clouds to 3D tree models

Trees are an integral component of the urban environment and important for human well-being, adaption measures to climate change and sustainable urban transformation. Understanding the small-scale impacts of urban trees and strategically managing the ecosystem services they provide requires high-resolution information on urban forest structure, which is still scarce. In contrast, there is an abundance of data portraying urban areas and an associated trend towards smart cities and digital twins as analysis platforms. A GIS workflow is presented in this paper that may close this data gap by classifying the urban forest from LiDAR point clouds, detecting and reconstructing individual crowns, and enabling a tree representation within semantic 3D city models. The workflow is designed to provide robust results for point clouds with a density of at least 4 pts/m² that are widely available. Evaluation was conducted by mapping the urban forest of Dresden (Germany) using a point cloud with 4 pts/m². An object-based data fusion approach is implemented for the classification of the urban forest. A classification accuracy of 95 % for different urban settings is achieved by combining LiDAR with multispectral imagery and a 3D building model. Individual trees are detected by local maxima filtering and crowns are segmented using marker-controlled watershed segmentation. Evaluation highlights the influences of both urban and forest structure on individual tree detection. Substantial differences in detection accuracies are evident between trees along streets (72 %) and structurally more complex tree stands in green areas (31 %), as well as dependencies on tree height and crown diameter. Furthermore, an approach for parameterized reconstruction of tree crowns is presented, which enables efficient and realistic city-wide modeling. The suitability of LiDAR to measure individual tree metrics is illustrated as well as a framework for modeling individual tree crowns via geometric primitives.     

一种改进的盐滴定法测定氧化锰矿物的电荷零点

以针铁矿为对照，采用电位滴定法（PT）、快速电位滴定法（RPT）、盐滴定法（ST）和改进的盐滴定法（IST）研究了几种氧化锰矿物的电荷零点（PZC）。结果表明：PT法测得酸性水钠锰矿、锰钾矿和钙锰矿的PZC分别为1．18、1．98和3．98，RPT法的结果分别为1．75、2．10和3．50。而ST法测得氧化锰矿物的△pH与横轴没有交点，但延长加入0．5ml 2mol L^-1 KCI溶液后的平衡时间至24h，获得上述样品的PZC分别为0．98、1．72和3．31。经典ST法通过改进，可以测定氧化锰矿物的PZC，其方法简单，结果与PT、RPT法有可比性。     

Volume density of earthworm burrows in compacted cores of soil as estimated by direct and indirect methods

After earthworms of the species Aporrectodea caliginosa and A. rosea had burrowed in compacted cores of soil for 68 days the cores were sectioned horizontally. The upper surface of each sectioned layer of soil was photographed before it was dissected and the dimensions of all burrows within the layer measured. Volume densities calculated from the direct measurement of burrows were compared with the values calculated by stereology from data obtained from two image analysis methods, computerised image analysis and point counting with a systematic lattice. The assumption implicit in all stereology calculations was satisfied for this experiment in that the burrows of both species showed no preferred orientation in the compacted soil. Computerised image analysis could not measure the density of all burrows in the photographs because of the lack of contrast between cast-filled burrows and the soil and the complex shapes of the burrows. Although the volume densities of A. caliginosa burrows calculated from point counts were correlated with the values calculated from direct measurement, point counting over-estimated volume densities by two to three times. In the experiment, A. rosea produced too few airfilled burrows for the lattice to detect. The relative ratios of air-filled to cast-filled burrows calculated from the point counts suggested that approximately two-thirds and eight-ninths of the burrows of A. caliginosa and A. rosea, respectively, were filled with casts.     

绵羊脾虚模型的复制及其瘤胃内环境、血清胃泌素和穴位温度变化规律的研究

应用中药番泻叶,按14g/kg体重/d,给12只绵羊煎汤内服。绵羊于5.3±0.4 d、8.3±0.4d、10.5±0.5d出现脾虚初期、中期、后期症状。随脾虚证的加重,瘤胃液pH值、纤毛虫数及其活力逐渐降低;大、中型纤毛虫比率渐降,小型纤毛虫比率渐升。在中、后期这种变化与实验前相差非常显著(P<0.01)。血清胃泌素含量,在脾虚初期有上升趋势(P>0.05),而中、后期逐渐下降(P<0.01),临死前最低。鼻俞、脾俞、百会穴温度从初期到后期逐渐降低,中、后期显著低于实验前(P<0.01)。脾虚后期绵羊病理解剖变化主要表现消瘦,贫血,胃肠卡他性炎症以及轻度心、肝,肺、肾实质性变性。     

固醇调节元件结合蛋白裂解激活蛋白(SCAP)的研究进展

对SCAP的结构、功能、单核苷酸多态性等方面作一综述,并就固醇对SCAP的反馈性调节机制进行讨论。     

基于三维激光扫描点云的树冠体积计算方法

针对树冠形状不规则,树冠体积难以测量和计算的问题,提出一种基于三维激光扫描点云的树冠体积计算方法——体元模拟法,即以固定大小的体元模拟不规则的树冠形状.首先将树冠沿树高方向以k为步长进行等距离分段,把每一段树冠的点投影到垂直于树高方向的平面上,再对该平面划分成大小为k×k的像元,根据投影到各个像元内点的数量,判断该像元的有效性,统计有效像元的数量T,则树冠体积为T个k×k×k的体元之和.经试验,当体元边长等于冠径的1/10时,计算的树冠体积达到稳定.该算法对于任何树种不用考虑树冠的形状,减少了人为判别导致的差异,适用于三维激光扫描树木树冠体积的计算.     

Identifying sources of polycyclic aromatic hydrocarbons (PAHs) in soils: distinguishing point and non-point sources using an extended PAH spectrum and <Emphasis Type="Italic">n</Emphasis>-alkanes

Background, aim, and scope  Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants. They are formed during pyrogenic and diagenetic processes and are components of petrogenic materials such as oils and coals. To identify PAH sources, several studies have employed forensic methods, which may be costly to execute. Although a large number of possible forensic methods are available (e.g., total ion chromatograms, PAH ratios, PAH alkyl homologue series, isoalkanes and isoprenoids, steranes and terpanes, stable isotope ratios, n-alkanes), one has to decide which method is the appropriate cost effective screening approach. In this study, three approaches were tested and compared by measuring (1) an extended PAH spectrum (i.e., 45 instead of the common 16 EPA-PAHs), (2) PAH ratios and (3) n-alkanes to determine if point sources are distinguishable from non-point sources, and if an individual source can be distinguished from a multiple source contaminated site in the study area. In addition, the study evaluated whether these methods are sufficient for source identification of selected samples, and if they constitute a sound strategy for source identification prior to the selection of more cost intensive methods. Materials and methods  Eighteen samples with previously characterized PAH point sources (previously characterized point sources in the Mosel and Saar region) were analyzed. Additionally, three river bank soils of Mosel and Saar rivers with known non-point PAH sources were investigated. The point sources were two gasworks, a tar impregnation facility, a creosoted timber, an acid tar, a tank farm, and a diesel contaminated site. Non-point sources were hard coal particles and atmospheric inputs in river bank soils. All samples were extracted with hexane and acetone, analyzed with a gas chromatograph coupled to a mass spectrometer for PAH distribution patterns and ratios. n-Alkanes were measured by a gas chromatograph equipped with a flame ionization detector. Results  Samples collected from point sources and non-point sources were analyzed by the use of three forensic methods, i.e., PAH patterns of an extended PAH spectrum, PAH ratios and n-alkanes. Identification by PAH patterns alone was insufficient for the non-point sources and some point sources, since the n-alkanes must be measured, as well. The use of PAH ratios with only 16 EPA-PAHs is less indicative in determining multiple sources because source assignments (or categories) change depending on the ratio used. Discussion  This study showed that by employing an extended PAH spectrum it is possible to fingerprint and distinguish sources. The use of alkylated PAHs is essential for identifying petrogenic sources. It is insufficient to rely exclusively on either the common 16 EPA-PAHs or the ratios to the parent PAHs when identifying non-point sources. Source identification using PAH ratios is only reliable if both parent and alkylated PAHs are measured. n-Alkane analyses provide more detailed information about petrogenic sources by verifying the presence of oils, diesel, gasoline, or coal in non-point sources. Conclusions  The three methods tested were deemed sufficient to distinguish between point and non-point PAH sources in the samples investigated. The use of an extended PAH spectrum provides the first step toward identifying possible sources. It simplifies the decision whether additional forensic methods should be necessary for more detailed source identification. Recommendations and perspectives  The determination of PAH alkyl homologue series, biomarkers, and isotopes is often advised (Kaplan et al., Environ Forensics 2:231–248, 2001; Oros and Simoneit, Fuel 79:515–536, 2000; Wang and Fingas, Mar Pollut Bull 47:423–452, 2003). The methods involved are complex and often expensive. We recommend a relatively uncomplicated and cost-effective method (i.e., extended PAH spectrum) before further and more expensive forensic investigations are to be conducted. Additional research with an extended sample set should be carried out to validate these findings for other sources and sites. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Spatial distribution of fungal communities in a coastal grassland soil

In grasslands, saprotrophic fungi, including basidiomycetes, are major decomposers of dead organic matter, although spatial distributions of their mycelial assemblages are little described. The aim of this study was to characterise the scale and distribution of saprotrophic fungal communities in a coastal grassland soil using terminal restriction fragment length polymorphism (T-RFLP).Soil fungi were sampled at Point Reyes, California, USA, by taking forty-five 26 mm diam. cores in a spatially defined manner. Within each sampled core, complete core sections at 1-2 cm and 14-15 cm depths were removed and sub-sampled for DNA extraction and amplification using the primer pairs ITS1F-FAM/ITS4 (general fungi) or ITS1F-FAM/ITS4B (basidiomycete-specific).Nonmetric Multidimensional Scaling showed that general fungal communities could be clearly separated by depth, although basidiomycete communities could not. There were no strong patterns of community similarity or dissimilarity for general or basidiomycete fungal communities at horizontal geographical distances from 25 cm to 96 m in the upper horizon. These results show considerable vertical, but little horizontal, variability in fungal community structure in a semi-natural grassland at the spatial scales measured here.     

Water Use and Reuse in Commercial Turkey Processing Facilities

A survey of turkey processing facilities was conducted to determine the average volume of water used per bird during processing, the average amount of recycled processing water, and the types of poultry processing antimicrobial treatments. Ninety-three surveys were sent out to turkey processing facilities in the United States. Twenty-six surveys were completed and returned (28%). The combined processing capacity of the 26 facilities that responded to the survey was approximately 1.03 million birds per day or 71% of the total US turkey production (252 million annually). Most of the facilities that responded to the survey reported operating 5 d each week using city water (85%) and discharging wastewater through the city sewer system (77%). The average amount of water used during processing was reported to be approximately 30 gal per turkey—an increase of 23% with the implementation of the Hazard Analysis and Critical Control Point program. Approximately 92% of the respondents reported using a cage or truck washing station. Thirty-one percent of the facilities reported that they recycle processing water. Data from the present survey may be of interest to turkey processing facilities that want to establish a water conservation program.