Quantitative analysis of riparian herbaceous community in Liaohe River Conservation Area and its tributaries北大核心CSCD

Research on community characteristics of riparian herbs is an important scientific basis of riparian vegetation rehabilitation. This study aimed to investigate the species diversity and quantitative characteristics of riparian herbs in Liaohe River Conservation Area and its tributaries. Herbaceous communities were investigated by sample line method. Group average clustering analysis and detrended correspondence analysis (DCA) were used to find the major environmental factors affecting the distribution pattern of riparian herbaceous communities. The result showed altogether 154 herbaceous species, belonging to 40 families and 96 genera. The riparian herbaceous species diversity was found to be correlated to river slope, sinuosity and stream order, being lower in rivers of mountain area than in rivers of plain area, and higher in tributaries than in Liaohe River Conservation Area. Clustering analysis classified the herbaceous communities into 23 types, being dominated by hygrophytes including communities of Echinochloa crusgalli, Oenanthe javanica, Polygonum hydropiper, Murdannia keisak, Artemisia selengensis, Scirpus triqueter, Heleocharis soloniensis, Pycreus sanguinolentus, Cyperus fuscus, Phragmites australis, Polygonum amphibium, Carex diandra + Artemisia selengensis and Carex diandra + Rorippa islandica. Correlation analysis between DCA ordination axes and environmental factors showed that the altitude, river slope, sinuosity and stream level were the major environmental factors affecting the distribution pattern of herbaceous communities in the riparian zone of Liaohe River Conservation Area and its tributaries. The results of CCA showed that the contribution ratio of stream level was the highest, followed by altitude and slope, with sinuosity the last. The results suggested that riparian herbaceous characteristics are affected by the comprehensive force of altitude, river slope, sinuosity and stream order, and that Calamagrostis epigeios, Triarrhena sacchariflora and Phragmites australis are suitable species for riparian vegetation rehabilitation.     

The distribution and availability of phosphorus fractions in restored cut slopes soil aggregates: a case study of subalpine road,Southwest China

● There was no significant difference in soil aggregates TP along altitude gradient. ● Overall, PAC dropped steadily as aggregate size increased. ● In soil aggregate sizes, TPi > TPo > R-P at 3009,3347 and 3654 m except 3980 m. ● Active NaHCO₃-Pi was the main AP source. ● Proportion of small aggregate sizes was emphasized to increase AP storage. The distribution and availability of phosphorus (P) fractions in restored cut slope soil aggregates, along altitude gradients, were analyzed. Samples were collected at 3009, 3347, 3654 and 3980 m of altitude. We examined soil aggregates total phosphorus (TP), available phosphorus (AP) and phosphorus activation coefficient (PAC), and discovered that there was no significant difference in TP levels between all four altitudes samples (p > 0.05). However, there was a significant difference in AP at 3009, 3347 and 3980 m of altitude (p < 0.05). At the altitudes of 3009, 3347 and 3654 m, the AP accumulation in small size aggregates was more advantageous. Overall, PAC dropped steadily as soil aggregates sizes increased, as shown: PAC (3654 m) > PAC (3347 m) > PAC (3009 m) > PAC (3980 m). In all particle size soil aggregates, the distribution of the P fractions was as follows: total inorganic phosphorus (TPi) > total organic phosphorus (TPo) > residual phosphorus (R-P), at 3009, 3347 and 3654 m, but a different registry was observed at 3980 m of altitude: TPo > TPi > R-P. Through correlation and multiple stepwise regression analysis, it was concluded that active NaHCO₃-Pi was the main AP source. It was also suggested that more attention should be given to the ratio of small particle size aggregates to increase soil AP storage. In order to improve the activation capacity and supply of soil P, along with promotion of the healthy development of soil ecosystem on slope land, it was suggest that inorganic P fertilizer and P activator could be added to soil at both low (3009 m) and high altitudes (3980 m).     

A practical approach to predict the duration of the growing season for European lakes

This work presents the first practically useful models to estimate the duration of the growing season (GS in days) for European lakes. GS is a fundamental parameter in limnology, where it is used, e.g., to calculate lake characteristic annual primary production (in g ww/m²·yr) from measurement data in g C/l·day. We have presented two simple empirical regression equations where GS is estimated from latitude. We have also introduced a more comprehensive model. It is derived from a previously presented well calibrated and validated model predicting lake epilimnetic temperatures from readily available data on latitude, altitude, continentality (distance from the Sea) and lake volume. Operationally, the duration of the growing season (GS in days) is defined from the predicted number of days when epilimentic water temperatures are higher than 9°C. The two modelling approaches are based on different presuppositions and they have been derived and tested from different data-sets. A model comparison has shown that the overall correspondence in predicted GS-values between the methods is very good. Evidently, the more comprehensive model can provide more relevant GS-predictions for many lakes since it also accounts for differences among lakes in altitude, continentality and volume.     

高空飞行的环境影响研究进展

航空运输业的高速发展的同时,环境问题亦不容小觑。民航是我国重要的交通运输方式之一,但我国民航运输业对于高空飞行对环境的影响的研究却很少。航空器巡航阶段属于高空飞行,占整个飞行时间的80%,因飞行距离长,距离地面高,所带来的温室效应具有放大效果,引起了国内外学者的广泛关注。文章概述了高空飞行的危害,认为CO_2排放和凝结尾生成是大气温室效应的直接污染源,进而对国内外典型的高空飞行影响评估模型进行阐述,并分析研究了高空飞行的温室效应防治措施。     

高空供氧装备工程设计中的生理基础

论述了在“背心──抗Ｇ服”系统供氧装备的研制中遇到有关装备设计中的生理问题，用系统论的观点对上述问题作一介绍，以期达到使飞机工程设计和防护生理研究人员在理论和实践上取得一致认识的目的。     

Long-term air monitoring of organochlorine pesticides using Semi Permeable Membrane Devices (SPMDs) in the Alps

Atmospheric sampling of organochlorine pesticides (OCPs) was conducted using Semi Permeable Membrane Devices (SPMDs) deployed in the Alps at different altitudinal transects for two consecutive exposure periods of half a year and a third simultaneous year-long period. Along all the altitude profiles, the sequestered amounts of OCPs increased in general with altitude. SPMDs were still working as kinetic samplers after half a year for the majority of the OCPs. However, compounds with the lowest octanol-air partition coefficient (K_oa), reached equilibrium within six months. This change in the SPMD uptake was determined for the temperature gradient along the altitude profile influencing K_oa, OCPs availability in the gaseous phase, and SPMD performance. In sum, it seems two effects are working in parallel along the altitude profiles: the change in SPMD performance and the different availability of OCPs along the altitudinal transects determined by their compound properties and concentrations in air.     

Nutritional constraints on mountain baboons (Papio ursinus): Implications for baboon socioecology

Summary Populations of baboon (Papio sp.) at geographic and climatic extremes for the genus show a tendency to one-male organization, whereas most baboons live in multimale social groups; this effect has been attributed largely to limitation of food supply, but baboons' complex diet has hindered proper nutritional analyses. To test these optimal-diet explanations of social variation, we quantified intake and used phytochemical analysis of foods to compare the nutrition, during seasonal changes, of two groups of mountain baboons (P. ursinus) living at different altitudes of a continuous grassland habitat. The majority of plant foods were eaten uniquely by one or other group, though their altitudinal separation was only 400 m, and the time budget of feeding choices varied with age-sex class as well as season. Converting to a common currency of nutrients reveals that baboons gained the same yield from a unit time spent foraging (whether this is measured in edible dry weight, or simply protein) in both groups, despite their differing mean altitude, whereas seasonal variation was large and statistically significant. Increased feeding time at the winter bottleneck made no effective compensation for the poorer food yields: in late winter there was a minimum for daily nutrient gain at both altitudes. Apparently this population is already at an extreme for the time animals devote to foraging in winter, when they rely on inconspicuous and slow-to-harvest swollen shoot bases and underground plant storage organs. Since an individual's nutrient yield does not vary with altitude, we conclude that socioecological parameters are effectively optimized for feeding. Since contest competition is absent, this adjustment of foraging efficiency is largely through the effect of differential density on scramble competition. Differences in social structure are considered to be a secondray consequence of optimal foraging, mediated through altitudinal variation in either population density or in day range limits.     

Comparative trends and seasonal variation of ⁷Be, ²¹⁰Pb and ¹³⁷Cs at two altitude sites in the central part of France

The atmospheric concentrations of ¹³⁷Cs, ²¹⁰Pb, and ⁷Be were measured over a three-year period at two research stations located less than 12 km apart and at different altitudes (puy de Dôme, 1465 m a.s.l. and Opme, 660 m a.s.l., France). Seasonal trends in all radionuclides were observed at both stations, with high concentration measured during the summer and low concentrations during the winter. The ²¹⁰Pb concentrations at both stations were similar to each other. Higher concentrations of both ⁷Be and ¹³⁷Cs were measured at puy de Dôme than at Opme. These observations can be explained by the stratospheric and upper tropospheric sources of ⁷Be and the long-range transportation of ¹³⁷Cs at high altitudes. Air mass origins during sampling periods were classified into several groups by their route to the stations (marine, marine modified, continental and mediterranean). We observed that ⁷Be concentrations were constant regardless of the air mass origins, unlike ¹³⁷Cs and ²¹⁰Pb concentrations that increased when influenced by continental air masses. Higher ⁷Be concentrations were observed when air masses were arriving from the upper troposphere than from the boundary layer, the opposite was observed for ¹³⁷Cs. The temporal trend in concentrations of ⁷Be shows good agreement with previous modelling studies suggesting that there is a good understanding of its sources and the atmospheric vertical mixing of this radionuclide. The sources and mixing of ²¹⁰Pb, however, seem to be more complex than it appeared to be in previous modelling studies.     

Mercury accumulation in the surface layers of mountain soils: a case study from the Karkonosze Mountains, Poland

The study was aimed to examine total concentrations and pools of Hg in surface layers of soils in the Karkonosze Mountains, dependent on soil properties and site locality. Soil samples were collected from a litter layer and the layers 0-10 cm and 10-20 cm, at 68 sites belonging to the net of a monitoring system, in two separate areas, and in three altitudinal zones: below 900 m, 900-1100 m, and over 1100 m. Air-borne pollution was the major source of mercury in soils. Hg has accumulated mainly in the litter (where its concentrations were the highest), and in the layer 0-10 cm. Hg concentrations in all samples were in the range 0.04-0.97 mg kg⁻¹, with mean values 0.38, 0.28, and 0.14 mg kg⁻¹ for litter and the layers 0-10 cm and 10-20 cm, respectively. The highest Hg concentrations in the litter layer were found in the intermediate altitudinal zone, whereas Hg concentrations in the layer 0-10 cm increased with increasing altitude. Soil quality standard for protected areas (0.50 mg kg⁻¹) was exceeded in a few sites. The pools of Hg accumulated in soils were in the range: 0.8-84.8 mg m⁻², with a mean value of 16.5 mg m⁻², and they correlated strongly with the pools of stored organic matter.