Demographic change is supposed to be the most important indirect driver for changing biodiversity. In this article, a systematic review of 148 studies was conducted to examine the scientific evidence for this relationship and to identify potential gaps in research. We explored the spatial distribution of studies, the categories addressed with respect to biodiversity and demographic change, and the ways in which their relationships were conceptualised (spatially and temporally) and valued. The majority of studies were carried out in Africa, Europe and North America. Our analysis confirms the trend that demographic phenomena were mostly found to negatively influence biodiversity. However, a considerable number of studies also point towards impacts that were context dependent, either positive or negative under certain circumstances. In addition to that we identified significant gaps in research. In particular, there is a lack of addressing (1) other demographic aspects such as population decline, age structure or gender differences, (2) spatial variability of, e.g. human population growth, (3) long-term effects of demographic processes, and (4) the context dependency (e.g. regulations/law enforcement, type of human activities, and choice of scale or proxy). We conclude there is evidence that the relationship between biodiversity and demographic change is much more complex than expected and so far represented in research. Thus, we call for a social–ecological biodiversity research that particularly focusses on the functional relation between biodiversity and human activities, namely the different types, context, and interdependent dynamics (spatial and temporal) of this complex relation.
Environmental manipulation experiments showed that species respond individualistically to each environmental-change variable. The greatest responses of plants were generally to nutrient, particularly nitrogen, addition. Summer warming experiments showed that woody plant responses were dominant and that mosses and lichens became less abundant. Responses to warming were controlled by moisture availability and snow cover. Many invertebrates increased population growth in response to summer warming, as long as desiccation was not induced. CO2 and UV-B enrichment experiments showed that plant and animal responses were small. However, some microorganisms and species of fungi were sensitive to increased UV-B and some intensive mutagenic actions could, perhaps, lead to unexpected epidemic outbreaks. Tundra soil heating, CO2 enrichment and amendment with mineral nutrients generally accelerated microbial activity. Algae are likely to dominate cyanobacteria in milder climates. Expected increases in winter freeze-thaw cycles leading to ice-crust formation are likely to severely reduce winter survival rate and disrupt the population dynamics of many terrestrial animals. A deeper snow cover is likely to restrict access to winter pastures by reindeer/caribou and their ability to flee from predators while any earlier onset of the snow-free period is likely to stimulate increased plant growth. Initial species responses to climate change might occur at the sub-species level: an Arctic plant or animal species with high genetic/racial diversity has proved an ability to adapt to different environmental conditions in the past and is likely to do so also in the future. Indigenous knowledge, air photographs, satellite images and monitoring show that changes in the distributions of some species are already occurring: Arctic vegetation is becoming more shrubby and more productive, there have been recent changes in the ranges of caribou, and "new" species of insects and birds previously associated with areas south of the treeline have been recorded. In contrast, almost all Arctic breeding bird species are declining and models predict further quite dramatic reductions of the populations of tundra birds due to warming. Species-climate response surface models predict potential future ranges of current Arctic species that are often markedly reduced and displaced northwards in response to warming. In contrast, invertebrates and microorganisms are very likely to quickly expand their ranges northwards into the Arctic. 相似文献
Twenty-two years after the last application of ring-14C-labeled atrazine at customary rate (1.7 kg ha−1) on an agriculturally used outdoor lysimeter, atrazine is still detectable by means of accelerated solvent extraction and LC-MS/MS analysis. Extractions of the 0-10 cm soil layer yielded 60% of the residual 14C-activity. The extracts contained atrazine (1.0 μg kg−1) and 2-hydroxy-atrazine (42.5 μg kg−1). Extractions of the material of the lowest layer 55-60 cm consisting of fine gravel yielded 93% of residual 14C-activity, of which 3.4 μg kg−1 was detected as atrazine and 17.7 μg kg−1 was 2-hydroxy-atrazine. The detection of atrazine in the lowest layer was of almost four times higher mass than in the upper soil layer. These findings highlight the fact that atrazine is unexpectedly persistent in soil. The overall persistence of atrazine in the environment might represent a potential risk for successive groundwater contamination by leaching even after 22 years of environmental exposure. 相似文献
Sediments from the Patos Lagoon Estuary in Southern Brazil and sludge from incoming effluents were assessed for the distribution of polycyclic aromatic hydrocarbons (PAHs). Shallow sediments adjoining the City of Rio Grande were found to be contaminated by PAHs mainly near urban effluent discharge, as well as in the port area. Effluents clustered into four groups according to their sources (sewage, industrial, runoff, and mixed), with each demonstrating different contributions of PAHs to the estuary. There was a predominance of runoff and mixed sources. Navigation activity was the second most important source of PAHs to sediments. The PAHs ratio identified the origin of these contaminants as essentially pyrolytic. The impact of PAHs as a result of uncontrolled disposal or accidental discharge of PAH-rich residues was suggested for several points. These points were primarily near gas stations and motor workshops. In about 30% of sampled sediments, the concentration of benzo[a]pyrene surpassed the Threshold Effects Level adopted for marine environments. 相似文献
Airborne fluoride was determined in the rainwater, surface soil and groundwater along a gradient of emission of a phosphate
fertilizer factory in Rio Grande, southern Brazil. Concentrations of fluoride in rainwater and groundwater achieved 3 mg l−1 and 5 mg l−1, respectively, and were dependent on pH. The fluoride deposited from emissions accumulated in a superficial horizon of soil
in quantities comparable to those in the manufactured end-products—up to 23,000 mg kg−1. Fluoride distribution in the environment is controlled by physical–chemical parameters of emission, rain intensity and soil
properties. The highest fluoride concentrations were registered at a close distance of up to 2 km from the factory. The distribution
of fluoride in groundwater resembled the same distribution in rainwater due to the high permeability of the local soils. Fluoride
penetration to the groundwater also depended on the type of vegetation cover. The groundwater in woodland areas was less affected
by contamination of fluoride than in the grassland areas, most probably because of the influence of eucalyptus throughfall,
which increases the pH of wet precipitates. 相似文献
Sexual selection has led to male morphologies and behaviours that either increase male attractiveness or their success in male–male competition. We investigated male traits under selection in the ant Hypoponera opacior, in which wingless males mate with pupal queens inside their natal colony and guard their partners for hours. The lack of female choice and fights among adult males makes this species an ideal study system to investigate sexual selection in the absence of these selective forces. We hypothesised that males, which emerge first and live longer, should have a higher mating success because of more mating opportunities, reduced competition and the ability to kill pupal competitors. We recorded the number and length of matings and tested whether these measures of male-mating success were associated with emergence order, lifespan and body size. Indeed, early emerged males mated more often and longer than their later-emerging rivals. Furthermore, longer-lived and larger males obtained more matings. Body size might be important because larger males either produce more sperm or perform better in mounting females. We found no evidence for a trade-off between body size and emergence time. Moreover, male removal manipulations revealed that males quickly adapt their guarding behaviour to changes in the competitive environment. Under reduced competition, males guarded their partners for shorter periods. In conclusion, these sib-mating ant males are under selection to develop fast, to live long, to be large and to be able to respond to the competitive situation in the nest. 相似文献