Edge Effects and Isolation: Red-Backed Voles Revisited

Abstract:  We examined demographic responses of California red-backed voles ( Clethrionomys californicus ) to forest fragmentation in southwestern Oregon at sites where this species has previously shown negative responses to fragmentation. Voles were captured in live traps and released. Voles were rarely caught in clearcuts surrounding 11 forest fragments, but relative vole density did not decrease from the forest-fragment interiors to edges. The first result agrees with previous findings at these sites 6 years earlier, but the latter result does not. There was no evidence that vole response to edge changes with fragment age. Two years of intensive mark-recapture efforts at two forest-fragment sites and two unfragmented (control) sites did not show negative effects of fragmentation on vole survival, an important demographic rate. Vole capture probabilities varied greatly across space and time on these four sites, which may explain the differences in vole responses to edge seen between this and the previous study. These results suggest that reliable appraisal of edge effects may be difficult for many species on small fragments because the data necessary to apply population estimators require great efforts to obtain and the use of indices leads to a confounding of detection probabilities with demographic change.     

Communities of Wood-Attacking Fungi in the Region of Oil and Gas Production

The communities of xylotrophic fungi were studied in the northern and middle taiga subzones of western Siberia, in forests growing in the region of oil and gas production and exposed to various anthropogenic factors (emissions of petroleum gas flares, oil pollution, spills of mineralized oil-field water, etc.). Structural and functional rearrangements in these communities were revealed, and the prevalence of rot in the tree stand was assessed.     

中子辐射防护服的设计、结构与效果

系统地阐述了中子辐射防护服的设计依据、结构、式样及使用效果。表明这是一种能有效地屏蔽热中子和中能中子的防护器具,可用于许多场所。     

Evaluation of greenhouse gas emissions from wetland and agriculture ecosystems in Sanjiang Plain

Carbon dioxide (CO₂), nitrous oxide (N₂O) and methane (CH₄) are important greenhouse gases (GHGs). The objective of this study is to quantify the aggregate GHG (CH₄, N₂O and CO₂) emissions and estimate economic losses of three ecosystems (marsh, paddy field and upland) in the Sanjiang Plain, excluding the Muling-Xiangkai Plain, south of Wanda Mountain. The results indicate the economic losses from GHG emissions of marshes were from 6.40 to 7.75?×?10⁹ CNY (Chinese Yuan), those of paddy fields were from 1.41 to 3.20?×?10⁹ CNY; and from uplands were from 0.26 to 0.49?×?10⁹ CNY. Using linear trend analysis, the economic losses through GHG emissions of marshes fell between 1982 and 2005, but those from paddy fields and uplands increased. In our study, the sequence in magnitude of the economic losses from GHG emissions was: marshes > paddy fields > uplands. In fact, the economic value of GHG emissions was negative because of these adverse impacts on the environment. This article could provide a reference for calculation of GHG exchange. The results suggest that improvement of fertiliser use efficiency for more precise agricultural management and returning straw to cropland could mitigate GHG emissions and would help to achieve sustainable development.     

The Ecological Significance of the Coexistence of Sulphur Dioxide and Hydrogen Sulphide in Volcanic Fumaroles

The relative concentrations of hydrogen sulphide and sulphur dioxide in volcanic gases cannot be explained simply by the temperatures and pressures, and appear as the result of the influence of different natural factors. SO₂ is directly related to magma degassing, while H₂S can be produced by the reaction of acidic solutions on dispersed sulphide minerals.

As long as these inputs to the surface environment are of moderate extent, then readjustment of redox conditions to an equilibrium situation will occur; a permanent disequilibrium will result in increased contributions of any component.

A wide spectrum of trace elements is normally associated with the presence of sulphur compounds in volcanic areas; their importance can be estimated for any system on the basis of the quantitative relationship between the oxidized and the reduced sulphur species. Extensive polluting effects can be produced by a continuous flow from a deep magmatic source, while minor consequences are associated with a re-circulation in the surface environment of heavy metals from previous volcanic activities.     

道光三年（1823年）华北大水初析

1823年华北大水对清王朝盛衰转折变化有很深远的影响。本文根据史料对这次大水的雨情、水情、灾情进行了较全面的分析,并将这次大水同清代其它各次大水进行比较,阐明这场大水影响深远的原因,并指出存在一个多方面因子所组成的自然灾害系统。     

Synchrony in egg-laying and reproductive success of neighboring common murres,Uria aalge

Common murres (Uria aalge) are highly colonial; pairs often breed at the highest possible densities, in bodily contact with neighbors. At Bluff, a colony in western Alaska, we tested for synchrony in egg laying at various spatial scales and found little evidence for higher synchrony, either within study plots of 15–195 pairs, or within subplots containing several pairs, than among plots in a 5-year study. Egg laying of neighbors generally was more synchronous than expected based on overall frequency distributions in laying dates, however. Breeding success was positively correlated with the number of breeding neighbors and the number of neighbors tending eggs or nestlings at the time of egg laying. Breeding success of pairs with neighbors was positively related to the breeding success of neighbors. Pairs that produced eggs synchronously with at least one neighboring pair had higher success than those that began breeding either before or after their neighbors. Most reproductive failures at Bluff are due to accidental egg loss and predation on eggs by common ravens, Corvus corax, soon after laying. By occupying space where a raven might otherwise land and defending their own eggs, active breeding neighbors locally reduce the probability of egg predation. Active breeding neighbors also are less likely to flush and accidentally dislodge nearby eggs when disturbed than are nonbreeders. Murres breeding synchronously with neighbors have the highest assurance of the presence of active breeding neighbors both at the time of egg laying and throughout their reproductive attempts. Groups of neighboring murres can be considered small “selfish herds,” demonstrating by-product mutualism through their continued presence and defense of their own eggs and nestlings. Despite the advantages of breeding synchronously with neighbors, early breeding may often be favored, however. Received: 22 January 1996/Accepted after revision: 16 June 1996     

APPLICATION OF THE PEBBLE COUNT NOTES ON PURPOSE,METHOD, AND VARIANTS1

ABSTRACT: The pebble count procedure (Wolman, 1954) is the measurement of 100 randomly selected stones from a homogeneous population on a river bed or bar, which yields reproducible size distribution curves for surficial deposits of gravel and cobbles. The pebble count is widely used in geomorphologr (and increasingly in river engineering) to characterize surficial grain size distributions in lieu of bulk samples, for which adequate sample sizes become enormous for gravels. Variants on the original method have been proposed, one of which, the so-called ‘zig-zag’ method (Bevenger and King, 1995), involves sampling along a diagonal line and drawing data points from many different geomorphic units. The method is not reproducible, probably because it incorporates stones from many different populations, and because an inadequate number of grains is sampled from any given population. Sampling of coarse bed material should be geomorphically stratified based on the natural sorting of grain sizes into distinct channel features. If a composite grain size is desired, the areas of the bed occupied by different populations can be mapped, pebble counts conducted on each, and a weighted average distribution computed.     

青藏高原东北部土族家庭能源消费特征

家庭能源消费特征因受地理环境及文化等影响而存在显著的人文空间差异,尤其是对于特色或边远少数民族地区,迫切需要加强相关调查实证研究。基于青海省100户土族家庭的实地调研,从收入水平分组视角考察其能源消费特征,分析家庭能源消费活动的环境效应,并构建物质流模型予以可视化分析。结果表明：土族家庭年人均能源消费量为3473 kgce,以煤炭、薪柴和秸秆等为主;随着收入水平提升,能源消费结构逐渐向多元化转变且对能源重要性的认知逐渐从生物质能源转向商品能源。家庭能源消费导致的年人均CO₂、N₂O、NO_X、SO₂和TSP的产生量分别为1856.87 kg、117.10 g、254.46 g、451.87 g和520.74 g。未来应增强清洁能源利用水平,统筹推进青藏高原地区生活能源消费的可持续转型。     

鄱阳湖典型洲滩湿地植物根系对水分垂向通量的影响

为了定量揭示湿地植物根系的水文效应,采用全物理机制的土壤水分运移数值模型,以鄱阳湖吴城湿地国家自然保护区的茵陈篙群落为例,模拟分析根系引起的水文效应.结果表明,根系将增加土壤饱和含水量与土壤进气值,显著改变土壤水分特征曲线（SWRC）与土壤蓄水能力;在考虑根系影响SWRC下模拟率定的土壤含水量与观测数据的时空变化一致：模型10和50cm观测值与拟合值相关系数由不考虑根系效应下的0.83提高至0.85,10和50cm深度土壤含水量的实测值与模拟值的均方根误差分别减少61%和83%.同时这种率定方法下的模拟相比以往的研究地下水补给根系层水量提高34%;考虑典型的根系效应蒸散发量和累积地下水边界向上通量分别增加10%和150%.而在气候极端干旱条件下地下水向上补给量在根系效应下增加7%~56%,累计差异可达38~312cm,同时蒸散发量增加13%.在植被生长旺季时若地下水埋深较深,则根系效应对蒸散发量的影响会放大.因此在进行相关的湿地生态水文过程和湿地水与物质平衡研究中,建议充分评估湿地植物根系的水文效应,并视计算的工况条件,考虑其水文效应在整个水文过程中的影响.