乡土物种补播对青藏高原高寒草甸群落稳定性的影响

为了探究高寒草甸天然草地补播乡土物种对草地群落稳定性的影响，本试验以垂穗披碱草（Elymus nutans）、异针茅（Stipa aliena）、中华羊茅（Festuca sinensis）、溚草（Koeleria cristata）、星星草（Puccinellia tenuiflora）、扁蓿豆（Melissitus rutenica）、冷地早熟禾（Poa crymophila）为试验材料，设置5种混播组合，于2017年在青海省贵南县天然草地上进行补播。试验采用方差比率法（Variance ratio，VR）、M.Godron贡献定率法（Contribution law）以及生物量稳定性分析方法，结果表明：5种组合补播后使得群落联结性降低、生物量稳定性增大，群落整体稳定性增强，正向着稳定方向发展；5种组合中，组合D （扁蓿豆+星星草+垂穗披碱草+异针茅+溚草）的生物量稳定性最大，是对草地恢复最有效的物种组合。本试验筛选出了对草地生态修复最有效的物种组合，为草地保护及利用提供了科学依据。     

Large‐scale patterns of fish diversity and assemblage structure in the longest tropical river in Asia

Although the Mekong River is one of the world's 35 biodiversity hot spots, the large‐scale patterns of fish diversity and assemblage structure remain poorly addressed. This study aimed to investigate the fish distribution patterns in the Lower Mekong River (LMR) and to identify their environmental determinants. Daily fish catch data (i.e. from December 2000 to November 2001) at 38 sites distributed along the LMR were related to 15 physicochemical and 19 climatic variables. As a result, four different clusters were defined according to the similarity in assemblage composition and 80 indicator species were identified. While fish species richness was highest in the Mekong delta and lowest in the upper part of the LMR, the diversity index was highest in the middle part of the LMR and lowest in the delta. We found that fish assemblages changed along the environmental gradients and that the main drivers affecting the fish assemblage structure were the seasonal variation of temperature, precipitation, dissolved oxygen, pH and total phosphorus. Specifically, upstream assemblages were characterised by cyprinids and Pangasius catfish, well suited to low temperature, high dissolved oxygen and high pH. Fish assemblages in the delta were dominated by perch‐like fish and clupeids, more tolerant to high temperatures, and high levels of nutrients (nitrates and total phosphorus) and salinity. Overall, the patterns were consistent between seasons. Our study contributes to establishing the first holistic fish community study in the LMR.     

Memory and resilience: A two-pronged approach to natural spaces in Colombia’s transition to a peaceful society

The analysis of spontaneous environmental initiatives undertaken by individuals and communities in cases of conflicts has led to a growing research field in social science, according to which the community-based stewardship of nature seems to conduce to the resilience of co-evolved social-ecological systems. In Colombia, where no such research exists so far, the conflict which officially ended in November 2016 has led to massive internal migration due to forced displacement, as well as to widespread degradation of the environment. Based on evidence provided by case studies of top-down and bottom-up living memorials and urban agriculture initiatives, the article explores the potential of urban greening in the process of memorialisation and in generating new social cohesion, as well as better living conditions in urban areas. It analyses cases both where the conflict has taken place and in the cities where refugees have settled, in order to explore avenues for public policies in post conflict Colombia. The author concludes that greening initiatives offer manifold, so far overlooked, opportunities to restoring social and ecological resilience in urban areas and thus contribute to a lasting peace in Colombia.     

Tracing regime influence on urban community gardening: How resource dependence causes barriers to garden longer term sustainability

This article explores how resource dependence leads to barriers to urban community gardening. Nine barriers to urban gardening were identified: finance, space, organizational structure, water, external damage, soil, communication, interpersonal issues, and participation issues. Using process tracing and grounded theory, we found that these barriers could be divided into three groups: primary, secondary, and participation barriers. Primary barriers are caused and directly influenced by the regime, whereas secondary barriers are the result of decisions and actions taken while addressing the primary barriers. All of these barriers cause frustration and affects the ability of the gardens to retain and acquire new members. This affects the longer term sustainability of the gardens and their potential to contribute to an urban governance transition.     

暖卫工程施工质量通病的发生与防治

本文论述了暖卫工程跑、冒、滴、漏、堵等五大质量通病的发生原因及防治方法建议等。     

A novel approach to studying the effects of temperature on soil biogeochemistry using a thermal gradient bar

The temperature dependence of chemical reaction rates and microbial metabolism mean that temperature is a key factor regulating soil trace gas emissions and hydrochemistry. Here we evaluated a novel approach for studying the thermal response of soils, by examining the effects of temperature on gas emissions and hydrochemistry in (a) peat and (b) soil from a Sitka spruce plantation. A thermal gradient was applied along an aluminium bar, allowing soil to be incubated contemporaneously from 2 to 18 °C. The approach demonstrated clear differences in the biogeochemical responses of the two soil types to warming. The peat showed no significant emission of CH₄ at temperatures below 6 °C, while above 6 °C, a marked increase in the rate of release was apparent up to 15 °C (Q₁₀ = 2.5) with emissions being similar between 15 and 18 °C. Conversely, CH₄ emissions from the forest soil did not respond to warming. Nitrate availability in the peat decreased by 90% between 2 and 18 °C (P < 0.01), whereas concentrations in the forest soil did not respond. Sulphate availability in the peat decreased significantly with warming (60%, P < 0.01), while the forest soil showed the opposite response (a 30% increase, P < 0.01). Conventionally, thermal responses are studied by incubating individual soil samples at different temperatures, involving lengthy preparation and facilities to incubate samples at different temperatures simultaneously. Data collected on a given thermal response is usually limited and thus interpolated or extrapolated. The thermal gradient method overcomes these problems, is simple and flexible, and can be adapted for a wide range of sample types (not confined to soil). Such apparatus may prove useful in the optimization of management practices to mitigate the effects of climate change, as thermal responses will differ depending on land use and soil type.     

Effect of sodium nitrite and sodium chloride on growth of lactic acid bacteria.

The effect of NaNO2 and NaCl on the growth of 24 lactic acid bacteria strains isolated from vacuum-packed cooked ring sausages were examined by analyzing different growth parameters with Bioscreen. NaNO2 had a very limited effect on the growth of lactic acid bacteria at 50 and 100 mg/l but at 400 mg/l a more pronounced inhibitory effect was found. Bacterial growth was enhanced by 1-2% (w/v) of added NaCl, while NaCl concentrations above 3% (w/v) had a clear inhibitory effect. Leuconostoc isolates seemed to be more sensitive to sodium nitrite and sodium chloride than homofermentative lactobacilli strains. Among homofermentative lactobacilli, the strains resembling Lactobacillus curvatus were more sensitive to NaCl than those resembling Lactobacillus sake.     

Comparison of cavity modification and community involvement as strategies for hornbill conservation in Thailand

We monitored breeding success of hornbills in Thailand for four sympatric species at Khao Yai National Park during 1981-2002 and six species at Budo-Sungai Padi National Park during 1994-2002. Within a 60 km² study area at Khao Yai, the well protected area, use of available cavities ranged from 94% in 1984 to 50% in 1993. Competition for nesting cavities was 40% of cavities available indicating the shortage of suitable cavity. We monitored the cavity condition and modified 48 cavities and, between 1996 and 2000, these contributed annually 23-45% of nestings that were successfully fledged (n = 352). Within the 90 km² at Budo Mountain, with heavy human disturbance, use of available cavities for nesting decreased from 81% in 1997 to 30% by 2001 and of successful fledging from 96% in 1997 to 55% in 1999, but both increased once our involvement with local communities had eradicated poaching and reduced disturbance. Competition for nesting cavities here was 26% of cavities available indicating the effect of poaching. Both strategies were successful in the short term but long-term management of cavities in large forest trees is required at Khao Yai and of forest disturbance at Budo.     

MAGNETIC RESONANCE IMAGING OF THE CANINE OPTIC NERVE

We describe the magnetic resonance (MR) imaging aspects of normal canine optic nerve, the diameter of the optic nerve as measured on MR images, and optimal MR sequences for the evaluation of the optic nerve using a 0.2 T MR unit. Three millimeter contiguous slides of the normal canine orbital region were acquired in transverse and dorsal oblique planes using a variety of tissue weighting sequences. It was apparent that detailed anatomic assessment of the optic nerve can be performed with low‐field MR imaging, but none of the sequences provided unequivocal superior image quality of the optic nerve. The mean diameter of the optic nerve sheath complex was 3.7 mm and of the optic nerve 1.7 mm. The intraorbital and intracanalicular parts of the optic nerve are consistently visible and differentiation between the optic nerve and optic nerve sheath complex is possible using low‐field MR systems.     

DGGE技术在瘤胃微生物多态性研究中的应用

利用传统的方法很难鉴别瘤胃微生物的差异,变性梯度凝胶电泳（DGGE）技术就很好地解决了该问题。DGGE是一种新型的用于检测核酸变异和点突变的电泳方法,具有可靠性强、重现性高、方便快捷等优点,可应用于瘤胃微生物群落多样性和动态性分析。