叶片投影盖度--描述植物群落结构的有效方法

植物群落盖度是描述植物群落结构及其重要性的主要指标之一。但长期以来植物群落盖度的测定往往是基于野外目视估计 ,影响了植物群落盖度特征度量的准确性。本文引入植物群落叶片投影盖度 (FPC)的概念 ,其含义是植物群落叶片覆盖地表的百分率 ,它具有生态意义明确、适于描述植物群落水平结构的特点。使用自制的FPC测量仪 ,在新疆的两个地区进行了FPC的测定 ,同时将测定数据与采用Stella模型工具开发的植物群落生理生态模型的模拟FPC值进行比较 ,二者相符较好。因此 ,认为FPC是描述干旱区植物群落水平结构的有效方法 ,并可用于所有植物群落叶片投影盖度的度量。     

The Role of Partnerships in U.S. Food Policy Council Policy Activities

Food Policy Councils (FPC) help to identify and address the priorities of local, state, and regional food systems with the goal of improving food systems through policy. There is limited research describing FPCs’ strategies for accomplishing this goal. As part of a larger study examining FPC policy efforts, this paper investigates the role of partnerships in food systems policy change. We conducted interviews with representatives from 12 purposefully selected FPCs in the United States and 6 policy experts identified by the selected FPC representatives to document and describe their policy work. One theme that emerged from those interviews was the role of partners. Interviewees described a range of partners (e.g., stakeholders from government, business, and education) and credited FPC partnerships with advancing their policy goals by increasing the visibility and credibility of FPCs, focusing their policy agenda, connecting FPCs to key policy inputs (e.g., local food community knowledge and priorities), and obtaining stakeholder buy-in for policy initiatives. Partnerships were also described as barriers to policy progress when partners were less engaged or had either disproportionate or little influence in a given food sector. Despite these challenges, partnerships were found to be valuable for FPCs efforts to effectively engage in the food policy arena.     

Neuropathological similarities and differences between schizophrenia and bipolar disorder: a flow cytometric postmortem brain study

Recent studies suggest that schizophrenia (SCH) and bipolar disorder (BPD) may share a similar etiopathology. However, their precise neuropathological natures have rarely been characterized in a comprehensive and quantitative fashion. We have recently developed a rapid, quantitative cell-counting method for frozen unfixed postmortem brains using a flow cytometer. In the present study, we not only counted stained nuclei, but also measured their sizes in the gray matter of frontopolar cortices (FPCs) and inferior temporal cortices (ITCs) from patients with SCH or BPD, as well as in that from normal controls. In terms of NeuN(+) neuronal nuclei size, particularly in the reduced densities of small NeuN(+) nuclei, we found abnormal distributions present in the ITC gray matter of both patient groups. These same abnormalities were also found in the FPCs of SCH patients, whereas in the FPCs of BPD patients, a reduction in oligodendrocyte lineage (olig2(+)) cells was much more common. Surprisingly, in the SCH FPC, normal left-greater-than-right asymmetry in neural nuclei densities was almost completely reversed. In the BPD FPC, this asymmetry, though not obvious, differed significantly from that in the SCH FPC. These findings indicate that while similar neuropathological abnormalities are shared by patients with SCH or BPD, differences also exist, mainly in the FPC, which may at least partially explain the differences observed in many aspects in these disorders.     

Eucalyptus foliar chemistry explains selective feeding by koalas

The koala is the quintessential specialist herbivore, feeding almost exclusively on Eucalyptus foliage. Consequently, the limitations imposed on the koala's diet by plant defences indicate the extent to which evolutionary adaptations allow mammalian herbivores to circumvent such defences. We tested whether a recently discovered group of plant secondary metabolites, the formylated phloroglucinol compounds (FPCs), deters koalas from feeding on some eucalypt foliage. We found that captive koalas ate less foliage in a single night from trees with high FPC concentrations. Individual trees also differ in the types of FPC they possess, but for a given eucalypt species, most FPCs were similarly effective deterrents. Two closely related and sympatric eucalypt species could be clearly separated by the amounts that koalas ate from each; however, this difference could not be explained by total FPC concentrations alone. We suggest, that in this case, the presence of a distinct type of FPC deters koala herbivory on the less palatable species, and may have facilitated the evolutionary divergence of these species. We conclude that plant defences probably play an important role in determining the distribution and abundance of koalas.     

Differential susceptibility to Eucalyptus secondary compounds explains feeding by the common ringtail (Pseudocheirus peregrinus) and common brushtail possum (Trichosurus vulpecula)

The effect of two plant secondary metabolites, tannins and formylated phloroglucinol compounds (FPCs), on the intake of Eucalyptus foliage by common ringtail (Pseudocheirus peregrinus) and common brushtail possums (Trichosurus vulpecula) was studied. We manipulated the amount of tannin that was free to bind with protein by coating foliage with polyethylene glycol 4000 (PEG) and relied on natural intraspecific variation in FPC concentrations. In contrast to ringtail possums, brushtail possums showed a greater tolerance to FPCs and ate more foliage when it was coated with PEG, suggesting that tannins limited their food intake. Brushtails detected the effects of tannins through immediate oral sensations rather than through systemic effects. Ringtail possums appeared highly tolerant of foliar tannins yet susceptible to low concentrations of FPCs. We could not detect any interaction between tannins and FPCs that affected the intake of Eucalyptus foliage by either species of possum. Although ringtail and brushtail possums are widely regarded as specialist and generalist folivores, respectively, their differential susceptibility to co-occurring secondary metabolites suggests greater complexity. Each possum species appears to be a specialist in its own right, which leads to a partitioning of available foliage. Brushtails avoid tannins and ringtails avoid FPCs.     

Foliage projective covers of overstorey and understorey strata of mature vegetation in Australia

At maturity, both overstorey and understorey foliage projective covers (FPC) tend to reach steady-state values which are correlated with the evaporative coefficient (k) in the water balance equation of the soil-plant-atmosphere continuum. Overstorey FPCs of mature communities increase linearly from 20 to 85% along the moisture gradient from arid to humid regions. Understorey FPCs in mature communities are relatively constant along the same moisture gradient, increasing only slightly from 40 to 47%. Plant communities which have overstorey FPCs different from the norm, appear to show a compensatory decrease or increase in understorey FPC so that the sum of the FPCs of overstorey and understorey is equal to that predicted for the region.     

Wastewater-Based Epidemiology of Stimulant Drugs: Functional Data Analysis Compared to Traditional Statistical Methods

Background

Wastewater-based epidemiology (WBE) is a new methodology for estimating the drug load in a population. Simple summary statistics and specification tests have typically been used to analyze WBE data, comparing differences between weekday and weekend loads. Such standard statistical methods may, however, overlook important nuanced information in the data. In this study, we apply functional data analysis (FDA) to WBE data and compare the results to those obtained from more traditional summary measures.

Methods

We analysed temporal WBE data from 42 European cities, using sewage samples collected daily for one week in March 2013. For each city, the main temporal features of two selected drugs were extracted using functional principal component (FPC) analysis, along with simpler measures such as the area under the curve (AUC). The individual cities’ scores on each of the temporal FPCs were then used as outcome variables in multiple linear regression analysis with various city and country characteristics as predictors. The results were compared to those of functional analysis of variance (FANOVA).

Results

The three first FPCs explained more than 99% of the temporal variation. The first component (FPC1) represented the level of the drug load, while the second and third temporal components represented the level and the timing of a weekend peak. AUC was highly correlated with FPC1, but other temporal characteristic were not captured by the simple summary measures. FANOVA was less flexible than the FPCA-based regression, and even showed concordance results. Geographical location was the main predictor for the general level of the drug load.

Conclusion

FDA of WBE data extracts more detailed information about drug load patterns during the week which are not identified by more traditional statistical methods. Results also suggest that regression based on FPC results is a valuable addition to FANOVA for estimating associations between temporal patterns and covariate information.     

Identification of quantitative trait loci influencing foliar concentrations of terpenes and formylated phloroglucinol compounds in Eucalyptus nitens

Leaves of eucalypt species contain a variety of plant secondary metabolites, including terpenoids and formylated phloroglucinol compounds (FPCs). Both terpene and FPC concentrations are quantitative traits that can show large variation within a population and have been shown to be heritable. The molecular genetic basis of this variation is currently unknown. Progeny from a field trial of a three-generation mapping pedigree of Eucalyptus nitens were assayed for terpenes and FPCs. Quantitative trait loci (QTL) analyses were conducted using a map constructed from 296 markers to locate regions of the genome influencing foliar concentrations of these plant secondary compounds. A large number of significant QTL for 14 traits were located across nine linkage groups, with significant clustering of QTL on linkage groups 7, 8 and 9. As expected, QTL for biosynthetically related compounds commonly colocated, but QTL for unrelated monterpenes and FPCs also mapped closely together. Colocation of these QTL with mapped candidate genes from the various biosynthetic pathways, and subsequent use of these genes in association mapping, will assist in determining the causes of variation in plant secondary metabolites in eucalypts.     

Distribution of foliar formylated phloroglucinol derivatives amongst Eucalyptus species

Formylated phloroglucinol compounds (FPCs) in Eucalyptus leaves are important determinants of feeding in marsupial folivores and have a wide range of other biological actions. We conducted a survey of the occurrence of formylated phloroglucinol compounds (euglobals, macrocarpals and sideroxylonals) in acetone-petrol extracts of 41 species of Eucalyptus from among seven informal subgenera growing on the East Coast of Australia. We used electrospray ionisation, Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTMS) to search crude extracts of eucalypt leaves for molecular weights characteristic of FPC compounds. We found masses characteristic of reported FPCs in 27 of the 41 species examined. The most frequently identified group of compounds was the sideroxylonals. Notable was the lack of known FPCs in the informal subgenus Monocalyptus.     

Assembly of plant communities in coastal wetlands—the role of saltcedar Tamarix chinensis during early succession

Aims The mechanisms of plant community assembly are hypothesized to vary at different stages of succession. Here, we explore the local assemblage structure of a herbaceous plant community at its early stage of succession in a supratidal wetland. Specifically, we assess the role of Chinese saltcedar (Tamarix chinensis), the lone dominant shrub species, in shaping the spatial structure and species composition in the local plant community, after landscape alteration.Methods We used the multivariate trend-surface analysis for analyzing the spatial structure of the community composition. A null model was also used to detect potential biotic interactions between species. Statistical significance was derived from a permutation test by randomizing the presence-absence matrix and functional traits independently. Sensitivity analysis by randomly selecting 50 subplots and repeating the null model tests was also done. Finally, rank correlation analysis was used to study the relationship between effect sizes and distance to nearest T. chinensis individuals.Important findings The herbaceous plant community was highly structured and shaped by the presence of T. chinensis. At local scale, two functional traits, plant height and leaf area, were found to be significantly convergent. Dispersal, environmental stress and interspecific competition played a trivial effect on the local community assembly. The facilitating effect of T. chinensis on the pioneering herbaceous plants, through acting as a wind shelter, was put forward as the dominant community assembly process.     

FPC Web tools for rice, maize, and distribution

Many clone-based physical maps have been built with the FingerPrinted Contig (FPC) software, which is written in C and runs locally for fast and flexible analysis. If the maps were viewable only from FPC, they would not be as useful to the whole community since FPC must be installed on the user machine and the database downloaded. Hence, we have created a set of Web tools so users can easily view the FPC data and perform salient queries with standard browsers. This set includes the following four programs: WebFPC, a view of the contigs; WebChrom, the location of the contigs and genetic markers along the chromosome; WebBSS, locating user-supplied sequence on the map; and WebFCmp, comparing fingerprints. For additional FPC support, we have developed an FPC module for BioPerl and an FPC browser using the Generic Model Organism Project (GMOD) genome browser (GBrowse), where the FPC BioPerl module generates the data files for input into GBrowse. This provides an alternative to the WebChrom/WebFPC view. These tools are available to download along with documentation. The tools have been implemented for both the rice (Oryza sativa) and maize (Zea mays) FPC maps, which both contain the locations of clones, markers, genetic markers, and sequenced clone (along with links to sites that contain additional information).     

Genetic screening and genetic counseling: knowledge, attitudes, and practices in two groups of family planning professionals.

67 obstetrical and gynecological physicians and 102 professional staff members of family planning clinics (FPCs) in the Pittsburgh, Pennsylvania, area returned questionnaires relating to knowledge of basic genetic principles and attitudes towards genetic screening and genetic counseling. The best understood genetic risk was Down's syndrome in children born to mothers over 40 years of age. Nearly 90% of physicians and 85% of FPC staff knew this but only 12% of physicians and 30% of FPC staff knew it is caused by chromosomal aberration. Next best understood defect is sickle cell anemia. In overall knowledge the physicians had a mean score of 4.45 of 7 genetic questions, FPC staff, 3.32. However, FPC workers who had received in-service genetic training scored 4.42 (p less than .001). Knowledge of the 2 genetic clinics in the area and acceptance of the principles of genetic screening were associated with the individual's acceptance of sterilization as a method of birth control and acceptance of abortion if the fetus had significant risk of being born deformed. Both of these associations were at the significant level for both physicians and FPC workers. Both physicians and FPC workers who have themselves had genetic counseling or who have family members who have had such counseling show higher acceptance levels. An association was also found between acceptance and genetic educational background. About 92% of respondents who had read articles or textbooks pertaining to genetics during the preceding year approved of including genetic information as part of maternal and child health projects compared with 82% of those who had not (p less than .02). Among the physicians 36% felt it should be required, 34% voluntary, and 30% did not know; for FPC workers, 59, 27, and 14%, respectively. Protestants and Jews tended to favor required premarital screening while Catholics tended to oppose it (p less than .007). It is disconcerting that over 50% of the physicians did not know the recurrence risk of PKU and over 20% did not know the gene is the basic unit of inheritance. While it is true that over 1/2 completed basic professional education more than 20 years ago when genetics was not part of the medical school curriculums this basic knowledge needs to have been acquired during continuing medical education. In this study more than 1/3 of the FPC staff indicated they had been asked to provide genetic counseling or had referred clients. This points up the importance of such workers in a comprehensive genetic counseling service.     

Ferric pyrophosphate citrate: interactions with transferrin

There are several options available for intravenous application of iron supplements, but they all have a similar structure:—an iron core surrounded by a carbohydrate coating. These nanoparticles require processing by the reticuloendothelial system to release iron, which is subsequently picked up by the iron-binding protein transferrin and distributed throughout the body, with most of the iron supplied to the bone marrow. This process risks exposing cells and tissues to free iron, which is potentially toxic due to its high redox activity. A new parenteral iron formation, ferric pyrophosphate citrate (FPC), has a novel structure that differs from conventional intravenous iron formulations, consisting of an iron atom complexed to one pyrophosphate and two citrate anions. In this study, we show that FPC can directly transfer iron to apo-transferrin. Kinetic analyses reveal that FPC donates iron to apo-transferrin with fast binding kinetics. In addition, the crystal structure of transferrin bound to FPC shows that FPC can donate iron to both iron-binding sites found within the transferrin structure. Examination of the iron-binding sites demonstrates that the iron atoms in both sites are fully encapsulated, forming bonds with amino acid side chains in the protein as well as pyrophosphate and carbonate anions. Taken together, these data demonstrate that, unlike intravenous iron formulations, FPC can directly and rapidly donate iron to transferrin in a manner that does not expose cells and tissues to the damaging effects of free, redox-active iron.     

An Evaluation of 18S rDNA Approaches for the Study of Fungal Diversity in Grassland Soils

Fungal community structure and diversity in two types of agricultural grassland soil were investigated by amplified 18S ribosomal DNA restriction analysis (ARDRA) and 18S ribosomal DNA sequence analysis. These two grassland sites represent a species-rich old hay meadow and an agriculturally improved site with low floristic diversity. Two primer sets were used in combination to amplify approximately 550 bp of rDNA from three major fungal groups, the zygomycetes, basidiomycetes, and ascomycetes, and clone libraries were created for each site. 18S ARDRA was used to analyze 170 rDNA clones, and three diversity indices were calculated. A small-scale culturing analysis was also carried out and the most common isolates analyzed using ARDRA and sequence analysis. The soil fungal community revealed by the rDNA approaches was significantly different from that produced by this limited culture-based analysis. Twenty-eight soil-derived clones were sequenced, and many represented fungal taxa rarely reported in culture-based studies. The PCR-based techniques detected differences in diversity between the two fungal communities and changes in patterns of dominance that paralleled higher plant diversity. The results suggest that 18S rDNA-based approaches are a useful tool for initial screening of fungal communities, and that they represent a more comprehensive picture of the community than plate culturing.     

Is the combination of topsoil replacement and inoculation with plant material an effective tool for the restoration of threatened sandy grassland?

Question: Is it possible to restore dry calcareous inland sand ecosystems with their characteristic plant community structure within a 4‐yr period by means of combined abiotic–biotic techniques (topsoil replacement, inoculation with raked/mown plant material from target areas)? Location: Upper Rhine valley, Germany. Methods: Two 4‐year experiments were carried out on former arable land, each in the proximity of a reference area bearing a similar complex of threatened sandy grasslands (experiment 1: fine‐scale; experiment 2: landscape scale). In both experiments we used nutrient‐poor deep‐sand substrate (abiotic approach), raked/mown inoculation material from target areas and grazing as management tool (biotic and management approach). The vegetation of the restoration and donor areas was sampled once a year and analysed by non‐metric multidimensional scaling (NMDS) ordination and target‐species ratios. Mixed linear models were calculated to determine effects of grazing (experiment 1) and year (both experiments). Results: NMDS revealed a continuous development of the restored sites towards the corresponding donor sites. Similarly, target‐species ratios of the restored sites tended towards the ratios of the donor sites. To date, grazing effects have mainly been structural: reduction of a carpet‐forming pleurocarpous moss species and of litter. In addition, cover of target species in relation to total plant cover was significantly enhanced by grazing in the last two study years. Conclusions: The combination of nutrient‐poor substrate, inoculation with raked/mown plant material and grazing proved to be a very effective restoration method for dry base‐rich sand ecosystems. After 4 yr the restored plant communities serve as well‐developed parts of a habitat network.     

Effects of grazing and fertilization on the relationship between species abundance and functional traits in an alpine meadow community on the Tibetan Plateau

Trait‐based approaches can provide a useful tool for linking plant attributes to community structure and ecosystem function. Seed mass and plant height play important roles in the dynamics of plant communities, but few empirical community level studies have tested this, especially in stressful environments. The aim of the present study was to determine if there is a relationship between functional traits (seed mass and plant height) and changes in species relative abundance (SRA) in response to grazing and fertilization. We measured SRA and plant functional traits for 40 common species in a Tibetan Plateau alpine meadow. In the fertilized meadow, seed mass and plant height was significantly positively correlated with the relative abundance of the species. In the grazed meadow, these variables were significantly negatively correlated. Our results demonstrates that plant functional traits can be used to predict the change of SRA in plant community. Grazing promotes the dominance of small‐seeded and short‐stature species, and fertilization facilitates the occurrence of large‐seeded and tall‐stature species.     

汶川地震滑坡迹地植物群落与环境的关系

为了加快汶川地震滑坡迹地人工恢复植被的进程,探讨地震诱发的滑坡迹地植物群落与环境的关系。在5·12地震重灾区北川境内选取29个样地进行植被调查,采用10个环境指标刻画植物群落的地形、空间位置和土壤养分特征;利用TWINSPAN、CCA、DCA和DCCA,分析植物种、植物群落和植物生活型与环境的关系。结果显示:1)研究区的植物群落可划分为9个类型。2)研究区环境变量对植物种的解释量为21.96%,第一排序轴与pH值、海拔、土壤质地相关,反映的是植物种从次生植物群落向原生植物群落变化。通过DCCA分析得出,环境变量对植物群落的排序解释了25.7%,第一排序轴与pH值、海拔、土壤质地的相关较强,反映植物群落按照耐旱、耐贫瘠→人工或先锋植物→未受损的植被变化;第二排序轴与土壤有机质、全氮含量、坡向的相关,反映的是植物群落从草本植物→乔灌草或者灌草植物变化。3)滑坡迹地的植物群落与未受损林地的植物群落物种存在较大差异。     

马尾松-栎类天然混交林群落最小面积确定及方法比较

用种面积曲线和群落系数面积曲线的方法对宜昌梅子垭地区一种主要植物群落类型的最小面积进行了研究。结果表明,对所研究的植被类型,样地布置为 １０ｍ ×１０ｍ 及２０ｍ ×２０ｍ 可满足不同研究精度的要求。群落系统面积曲线和种面积曲线一样,比较直观。虽然取样调查时工作量稍大,但运用群落系数面积曲线的方法可更多地包含种类组成及群落结构随面积而变化的信息,所确定的最小面积也能够真实地反映整个群落种类组成及结构的特征。     

The Relative Concentrations of Nutrients and Toxins Dictate Feeding by a Vertebrate Browser,the Greater Glider Petauroides volans

Although ecologists believe that vertebrate herbivores must select a diet that allows them to meet their nutritional requirements, while avoiding intoxication by plant secondary metabolites, this is remarkably difficult to show. A long series of field and laboratory experiments means that we have a good understanding of the factors that affect feeding by leaf-eating marsupials. This knowledge and the natural intraspecific variation in Eucalyptus chemistry allowed us to test the hypothesis that the feeding decisions of greater gliders (Petauroides volans) depend on the concentrations of available nitrogen (incorporating total nitrogen, dry matter digestibility and tannins) and of formylated phloroglucinol compounds (FPCs), potent antifeedants unique to Eucalyptus. We offered captive greater gliders foliage from two species of Eucalyptus, E. viminalis and E. melliodora, which vary naturally in their concentrations of available nitrogen and FPCs. We then measured the amount of foliage eaten by each glider and compared this with our laboratory analyses of foliar total nitrogen, available nitrogen and FPCs for each tree offered. The concentration of FPCs was the main factor that determined how much gliders ate of E. viminalis and E. melliodora, but in gliders fed E. viminalis the concentration of available nitrogen was also a significant influence. In other words, greater gliders ate E. viminalis leaves with a particular combination of FPCs and available nitrogen that maximised the nutritional gain but minimised their ingestion of toxins. In contrast, the concentration of total nitrogen was not correlated with feeding. This study is among the first to empirically show that browsing herbivores select a diet that balances the potential gain (available nutrients) and the potential costs (plant secondary chemicals) of eating leaves. The major implication of the study is that it is essential to identify the limiting nutrients and relevant toxins in a system in order to understand feeding behaviour.     

Variation in Community Structure across Vertical Intertidal Stress Gradients: How Does It Compare with Horizontal Variation at Different Scales?

In rocky intertidal habitats, the pronounced increase in environmental stress from low to high elevations greatly affects community structure, that is, the combined measure of species identity and their relative abundance. Recent studies have shown that ecological variation also occurs along the coastline at a variety of spatial scales. Little is known, however, on how vertical variation compares with horizontal variation measured at increasing spatial scales (in terms of sampling interval). Because broad-scale processes can generate geographical patterns in community structure, we tested the hypothesis that vertical ecological variation is higher than fine-scale horizontal variation but lower than broad-scale horizontal variation. To test this prediction, we compared the variation in community structure across intertidal elevations on rocky shores of Helgoland Island with independent estimates of horizontal variation measured at the scale of patches (quadrats separated by 10s of cm), sites (quadrats separated by a few m), and shores (quadrats separated by 100s to 1000s of m). The multivariate analyses done on community structure supported our prediction. Specifically, vertical variation was significantly higher than patch- and site-scale horizontal variation but lower than shore-scale horizontal variation. Similar patterns were found for the variation in abundance of foundation taxa such as Fucus spp. and Mastocarpus stellatus, suggesting that the effects of these canopy-forming algae, known to function as ecosystem engineers, may explain part of the observed variability in community structure. Our findings suggest that broad-scale processes affecting species performance increase ecological variability relative to the pervasive fine-scale patchiness already described for marine coasts and the well known variation caused by vertical stress gradients. Our results also indicate that experimental research aiming to understand community structure on marine shores should benefit from applying a multi-scale approach.