《Ambio》专刊<酸化水体的生物恢复--北方湖泊恢复研究>前言

20世纪70和80年代,"酸雨"成为一个主要公共政策问题.在加拿大和北欧的斯堪的纳维亚半岛的酸化水体中,生物群落及生境遭到频繁破坏,诸如土著鲑鱼和鳟鱼种群受损乃至灭绝的现象屡见不鲜.     

The Magnitude of Local Host Specif icity for Phytophagous Insects and its Implications for Estimates of Global Species Richness

Abstract: Estimates of the global number of arthropod species range from 2 million to more than 30 million species. One of the most critical assumptions affecting the higher of these estimates is the assumed magnitude of host specificity of phytophagous insects, which varies considerably. Difficulties in estimating this value are caused by both lack of satisfactory data sets and lack of methods for its objective calculation. We provide a new method for predicting host specificity for phytophagous insects at a local scale based on the concept of effective specialization. When the insect-plant host associations of a restricted number of plant species are known, we can predict the magnitude of host specificity when more plant species are included. Based on 2561 host observations of 697 beetle species on 50 plant species in the canopies of a tropical dry forest in Panama, we predict that host specificity for adult phytophagous beetles in this forest range from 7% to 10%. These values suggest that the higher estimates of global species richness are not tenable.     

Disentangling the effects of heterogeneity, stochastic dynamics and sampling in a community of aquatic insects

A dynamic and heterogeneous species abundance model generating the lognormal species abundance distribution is fitted to time series of species data from an assemblage of stoneflies and mayflies (Plecoptera and Ephemeroptera) of an aquatic insect community collected over a period of 15 years. In each year except one, we analyze 5 parallel samples taken at the same time of the season giving information about the over-dispersion in the sampling relative to the Poisson distribution. Results are derived from a correlation analysis, where the correlation in the bivariate normal distribution of log abundance is used as measurement of similarity between communities. The analysis enables decomposition of the variance of the lognormal species abundance distribution into three components due to heterogeneity among species, stochastic dynamics driven by environmental noise, and over-dispersion in sampling, accounting for 62.9, 30.6 and 6.5% of the total variance, respectively. Corrected for sampling the heterogeneity and stochastic components accordingly account for 67.3 and 32.7% of the among species variance in log abundance. By using this method, it is possible to disentangle the effect of heterogeneity and stochastic dynamics by quantifying these components and correctly remove sampling effects on the observed species abundance distribution.     

Simulating transport of 129I and idealized tracers in the northern North Atlantic Ocean

Transport of the radioactive tracer Iodine-129 (¹²⁹I, T _1/2 = 15.7 Myr) in the northern North Atlantic Ocean has been investigated using a global isopycnic Ocean General Circulation Model (OGCM) and observed data. ¹²⁹I originates mainly from the nuclear fuel reprocessing plants in Sellafield (UK) and La Hague (France), and is transported northwards along the Norwegian coast, and then into surface and intermediate layers in the Arctic Ocean through the Barents Sea and the Fram Strait, but also partly recirculating south along the eastern coast of Greenland. In the North Atlantic Subpolar Seas, ¹²⁹I is mainly found in dense overflow waters from the Nordic Seas being exported southwards in the Deep Western Boundary Current, and to a lesser extent in surface and intermediate layers circulating cyclonically within the Subpolar Gyre. Observed concentration of ¹²⁹I along a surface transect in the eastern Nordic Seas in 2001 is captured by the OGCM, while in the Nansen Basin of the Arctic Ocean the OGCM overestimates the observed values by a factor of two. The vertical profile of ¹²⁹I in the Labrador Sea, repeatedly observed since 1997 to present, is fairly realistically reproduced by the OGCM. This indicates that the applied model system has potential for predicting the magnitude and depth of overflow waters from the Nordic Seas into the North Atlantic Subpolar Seas. To supplement the information obtained from the ¹²⁹I distribution, we have conducted a number of idealized tracer experiments with the OGCM, including tracers mimicking pure water masses, and instantaneous pulse releases. New insight into time-scales of tracer transport in this region is obtained by utilizing a few recently developed methods based on the theory of Transit Time Distribution (TTD) and age of tracers. Implications for other types of “anomalies” in the northern North Atlantic Ocean, being anomalous hydrography or chemical tracers, and how they are interpreted, are discussed.     

Estimation of population parameters from aerial counts of North American mallards: a cautionary tale.

The accuracy of population estimates strongly interferes with our ability to obtain unbiased estimates of population parameters based on analyses of time series of population fluctuations. Here we use long-term data on fluctuations in the size of Mallard populations collected as part of the May Breeding Waterfowl Survey covering a large section of North America. We assume a log-linear model of density dependence and use a hierarchical Bayesian state-space approach in which all parameters are assumed to be realizations from a common underlying distribution. Thus, parameters for different populations are not allowed to vary independently of each other. We then simulated independent time series of aerial counts, using the estimated parameters and adding various levels of observation error. These simulations showed that the estimates of stochastic population growth rate and strength of density dependence were biased even when moderate sampling errors were present. In contrast, the estimates of the environmental stochasticity and the carrying capacity were unbiased even for short time series and large observation error. Our results underline the importance of reducing the magnitude of sampling error in the design of large-scale monitoring programs of population fluctuations.     

A general model for analyzing Taylor's spatial scaling laws

Taylor's spatial scaling law concerns the relation between the variance and the mean population counts within areas of a given size. For a range of area sizes, the log of the variance often is an approximately linear function of the mean with a slope between 1 and 2, depending on the range of areas considered. In this paper, we investigate this relationship theoretically for random quadrat samples within a large area. The model makes a distinction between the local point process determining the position of each individual and the population density described by a spatial covariance function. The local point process and the spatial covariance of population density both contribute to the general relationship between the mean and the variance in which the slope may begin at 1, increase to 2, and decrease to 1 again. It is demonstrated by an example that the slope theoretically may exceed 2 by a small amount for very regular patterns that generate spatial covariance functions that increase in certain intervals. We also show how properties of population dynamics in space and time determine this relationship.     

Determination of the dialdehyde glyoxal in workroom air-development of personal sampling methodology

The dialdehyde glyoxal (ethanedial) is an increasingly used industrial chemical with potential occupational health risks. This study describes the development of a personal sampling methodology for the determination of glyoxal in workroom air. Among the compounds evaluated as derivatizing agents; N-methyl-4-hydrazino-7-nitrobenzofurazan (MNBDH), 1,2-phenylenediamine (OPDA), 1-dimethylaminonaphthalene-5-sulfonylhydrazine (dansylhydrazine, DNSH) and 2,4-dinitrophenylhydrazine (DNPH), DNPH was the only reagent that was suitable. Several different samplers were evaluated for sampling efficiency of glyoxal in workroom air using DNPH as derivatizing agent; in-house DNPH coated silica particles packed in two different types of glass tubes, impingers containing acidified DNPH solution, filter cassettes containing glass fibre filters coated with DNPH, a commercially available solid phase cartridge sampler originally developed for formaldehyde sampling (Waters Sep-Pak DNPH-silica cartridge), and the commercially available SKC UMEx 100 passive sampler originally developed for formaldehyde sampling. Aldehyde atmospheres for sampler evaluation were generated with an in-house made vapour atmosphere generator coupled to a sampling unit, with the possibility of parallel sampling. The resulting glyoxal-DNPH derivative was determined using both LC-UV and LC-APCI-MS with negative ionization. By far, the highest recovery of glyoxal was obtained employing one of the in-house DNPH coated silica samplers (93%, RSD = 3.6%, n = 12).     

The generation of residual flows in Norway: an input-output approach

The generation of 35 different kinds of residuals is analyzed by an input-output approach for the Norwegian economy in 1970. The general tendency in the computations is that the final demand category, Export, especially export from the sectors Pulp and paper and Metals and minerals, is the main contributor of the flow of residuals generated each year.