以读者需求为导向 合理配置馆藏信息资源——兼论网络环境下党校图书馆馆藏信息资源建设

随着党校教学改革的不断深入和办学方向的转变,图书馆原有的纸质文献占绝大比例的传统型的馆藏信息资源结构已经很难满足读者的多层次需求。以读者的需求为导向,合理配置图书馆的馆藏资源是当前党校图书馆的当务之急。分析了党校图书馆读者的新需求和当前图书馆馆藏的现状,提出了合理配置馆藏资源的一些建议。     

Belowground carbon allocation patterns in a dry Mediterranean ecosystem: A comparison of two models

Total belowground C allocation (TBCA) accounts for a large fraction of gross primary production, it may overtake aboveground net primary production, and contributes to the primary source of detrital C in the mineral soil. Here, we measure soil respiration, water erosion, litterfall and estimate annual changes in C stored in mineral soil, litter and roots, in three representative land uses in a Mediterranean ecosystem (late-successional forest, abandoned agricultural field, rain-fed olive grove), and use two C balance approaches (steady-state and non-steady-state) to estimate TBCA. Both TBCA approaches are compared to assess how different C fluxes (outputs and inputs) affect our estimates of TBCA within each land use. In addition, annual net primary productivity is determined and C allocation patterns are examined for each land use. We hypothesized that changes in C stored in mineral soil, litter and roots will be slight compared to soil respiration, but will still have a significant effect on the estimates of TBCA. Annual net primary productivity was 648 ± 31.5, 541 ± 42.3 and 324 ± 22.3 g C m⁻² yr⁻¹ for forest, abandoned agricultural field and olive grove, respectively. Across land uses, more than 60% of the C was allocated belowground. Soil respiration (F_S) was the largest component in the TBCA approaches across all land uses. Annual C losses through water erosion were negligible compared to F_S (less than 1%) and had little effect on the estimates of TBCA. Annual changes in C stored in the soil, litter layer and roots were low compared to F_S (16, 24 and 10% for forest, abandoned agricultural field and olive grove, respectively), but had a significant effect on the estimates of TBCA. In our sites, an assumption that Δ[C_S + C_R + C_L]/Δt = 0 will underestimate TBCA, particularly in the abandoned agricultural field, where soil C storage may be increasing more rapidly. Therefore, the steady-state model is unsuited to these Mediterranean ecosystems and the full model is recommended.     

Carbon partitioning in ectomycorrhizal Scots pine seedlings

The complete carbon budget and the turnover rate of assimilated carbon of ectomycorrhizal Scots pine seedlings growing on natural humus were determined in microcosm conditions. The main aim was to improve understanding of the partitioning of the assimilated carbohydrates within seedlings associated with multiple ectomycorrhizal fungi, and to discover carbon dynamics of the mycorrhizosphere.Plant photosynthesis and below-ground respiration were measured in order to obtain the actual carbon assimilation and respiration rates at the time of measurements. Soon after the photosynthesis and respiration rate measurements the seedlings were pulse-labeled with ¹⁴CO₂ to follow carbon allocation to different plant, fungal and soil compartments and rhizosphere respiration. Long-term carbon allocation during the entire life span of the seedlings was estimated by measuring plant and mycorrhizal root-tip biomass. The ectomycorrhizal community was analyzed using morphotyping and ITS-sequencing.The ¹⁴C label was detected in rhizosphere respiration after 12 h and it peaked between 36 and 60 h after labeling. More than half of the assimilated carbon was allocated below-ground as biomass or respiration and higher mycorrhizal biomass increased the below-ground carbon turnover. The presence of Suillus variegatus affected the plant carbon balance in several ways. When S. variegatus was present, the below-ground respiration increased and this carbon loss was compensated by higher photosynthetic activity. Other fungal species did not differ between each other in their effects on carbon balance. Our findings indicate that some root-associated mycorrhizal fungal symbionts can significantly alter plant CO₂ exchange, biomass distribution, and the allocation of recently photosynthesized plant-derived carbon.     

Response of seedlings growth of Pinus sylvestriformis to atmospheric CO_2 enrichment in Changbai Mountain

IntroductionGIobaIchangehasbeenoneoftheimpoFtantis-suesandscientistspaycIoseattentiontoit.ThegreatimportanceofforestecosystemisreflectednotonlybytheirhUgebiomass,butaIsobytheirsignifi-cantroIeintheglobaIcarbonbaIance.Howtreesrespondtoclimaticchangesmightbeofgreatsig-nificance.ManystudiesindicatethattherisingatmosphericCo,leveIscanmakeasubstantialeffectonplantgroWthanddevelopment.SomeonethinkcommonlythattherisingCo,levelscanstimuIatepIantgroWthandbiomassproduction,sincephotosynthesisofC…     

城市地价监测点配置模式研究

地价监测点配置关系到城市地价水平的真实反映，影响到我国城市地价监测体系的系统性和规范性。本文提出以空间分层抽样技术为基础，首先确定城市地价监测点总量，然后选择一定的指标，分别确定地价监测点在城市内不同区域、不同用地类型、不同土地级别中的分布，经综合平衡，最后确定地价监测点配置方案。该模式解决了我国当前地价监测体系建立中如何配置监测点这一技术问题。     

安徽省驷马山引江灌溉工程水价制度研究

结合该工程的实际情况 ,在全面分析工程现行水价制度存在的主要问题的基础上 ,扼要讨论了工程的理论水价计算 ,对驷马山引江工程水价征收办法进行了较深入的研究。     

国外粮食物流的走向及我国的应对举措

科学、合理地组织粮食物流对降低粮食流通成本,提高粮食流通效率具有十分关键的作用.本文分析和总结了发达国家发展粮食物流的经验、面临的问题和未来的趋势及走向,在此基础上,就如何借鉴国外经验,依据WTO和市场经济发展的要求并结合我国粮食生产、流通的客观实际采取有效措施,促进我国粮食物流科学化运作和管理提出了一些具体的构想.意在对符合我国粮食流通规律和产销特点的粮食物流新格局的形成起到促进作用.     

Optimal allocation of resources in evaluating current sunflower inbred lines for resistance to Sclerotinia

Sclerotinia sclerotiorum (Lib.) de Bary is a major limiting factor for sunflower (Helianthus annuus) production. This study was conducted to (1) evaluate a large number of current sunflower lines for their reaction to Sclerotinia, and (2) determine the optimum allocation of resources for their selection. A set of 85 inbred lines was screened under artificial leaf infection in three environments. The test revealed ample variation for all resistance traits in the current germplasm. A line selected from NDBLOS, an oilseed sunflower germplasm poo, and its derivatives were most resistant to Sclerotinia. Lines derived from interspecific crosses with the wild species Helianthus tuberosus and Helianthus argophyllus also showed satisfactory Sclerotinia resistance. The evaluation of five plants per plot in two replications and four environments appears to be a reasonable allocation of resources in order to optimize the selection response.     

黄土高原植被对位配置技术研究

黄土高原的植被建设 ,既要遵循自然植被的地带性分布规律 ,又要充分考虑不同地形部位的小气候分异规律 ,坚持地形小气候条件与植物种生态位条件的相互对位配置。宏观环境的降水总量不足、水土流失严重和微观环境的风速、相对湿度是影响植物水量平衡 ,进而影响植物正常生长发育的主要因素。在不同的地类灵活采用隔坡软埂水平阶 ,漏斗式、燕尾式、竹节状聚流坑等径流聚集工程 ,均可使林木成活率和保存率达到 90 %以上 ,生长量提高 1倍以上。     

论厚层客土喷播技术的植物群落目标设定和植物种选配

 为建立稳定、高效的人工植物群落,必须对厚层客土喷播技术中的植物选择与植物群落的目标进行科学的确定。认为植物群落目标的设定应以遵循保证坡面稳定性的前提,实现与周围景观相协调,并且维护管理量小等原则。在此基础上,综合分析不同群落类型的生态稳定性以及影响因素,认为植物选择要以乡土植物为主,并按照恢复目标合理确定初期密度。坡面自身稳定性以及客土喷播层的质量,也是影响恢复植物群落能否顺利向设定目标群落方向演替的重要因素。