引入科研前沿对植物生理学教学方法的改进和效果分析     

龚春梅  王俊惠 《安徽农业科学》2015,(2):373-376

大学生普遍存在科研创新意识差、缺乏科研热情的现象.补充相关科研进展,将科研前沿引进课堂成为一种趋势,笔者对植物生理学光合作用这一章关于补充光合碳同化科研进展与否的教学实践结果进行对比分析,采用调查问卷的形式,围绕已讲授和未讲授光合碳同化适应性进化这一科研前沿进行调查,旨在实现学生对光合碳同化途径多元化发展进化的理解和深化,启发学生对固有知识的质疑和求解热情,达到提升科研兴趣和创新能力,实现精品课程培养满足国家和地方发展需要的高素质人才的目的.  相似文献   

对我国LULUCF碳计量监测方法的探讨     

高显连 《林业资源管理》2015,(2):46-50

围绕我国林业编制温室气体清单这一重要工作,介绍了IPCC关于LULUCF温室气体清单编制系列技术指南的技术要点和要求,阐明了我国林业温室气体清单编制工作的进展,提出了林业开展LULUCF碳监测工作未来面临的需求。同时,在分析美国、欧盟、加拿大等发达国家LULUCF温室气体清单编制做法和经验的基础上,提出了"在森林资源清查样地系统上构建"、"新布设LULUCF大样地系统"等2种开展LULUCF碳监测的思路,目的是为推动我国林业LULUCF碳监测达到国际先进水平提供建议。  相似文献   

The Relationship Between Vegetation Characteristics and Altitudes in Transitional Permafrost Zone in Xidatan,Qinghai-Tibetan Plateau     

Zhiwei WANG  Bentian MO  Leilei DING  Puchang WANG  Qian WANG  Ruixia LU 《农业科学与技术》2016,(6):1462-1467

Many studies showed that permafrost has profound influence on alpine ecosystem. However, former researches were mainly focused on typical points by temporal scales. There were few studies about the correlation between vegetation characteristics and different altitudes covering a large region in spatial pattern, especially in transitional permafrost(TP). There were continuous permafrost(CP) discontinuous permafrost(DCP) and seasonal frozen ground(SFG) in this study region. The types of permafrost changed from SFG to DCP, and finally become CP as the altitudes of Xidatan increase. In this paper, 112 845 points interpreted by HJ1-B(environment and disaster monitoring and prediction small satellite constellation), vegetation investigation points, thawing layer thickness research sites, ground temperature and water content observation plots were used to examine the spatial pattern of vegetation which were located in different altitudes in Xidatan, a typical TP region, in Qinghai-Tibetan Plateau. Vegetation characteristics, soil moisture content(SMC) and thaw depths were collected in 15 August to 25 August2012. Characteristics of vegetation were mainly represented by fractional vegetation cover(FVC) derived from the normalized difference vegetation index(NDVI), as well as above ground biomass(AGB). In this paper, we analyzed that the distinction of vegetation characteristics in each range through statistics data. These ranges were divided by varied altitudes. For examples, the ranges were divided into 50 m or 100 m. In this study we use a large area plots method to further discuss the relationship between the features of vegetation and the different regions of permafrost based on altitudes shifts in Xidatan. A diagram described the vegetation characteristics variability with rising altitudes in transitional permafrost region was drawn in this paper. Our results illustrated the FVCs first increased in SFG region and then decreased in DCP zone slowly, and in CP region FVCs soared then dropped dramatically. With the altitudes increased, the curve of FVCs indicated a parabolic distribution except a little difference in the first 200 m range.  相似文献   

湘西北长果安息香种群数量与分布格局     

张程 《湖南农业大学学报(自然科学版)》2011,37(6):615-620

对湖南石门壶瓶山景关门、桑植龙潭坪茅垭村样地的长果安息香(Changiostyrax raxdolichocarpa)种群数量和分布格局进行调查和分析。结果表明：长果安息香种群的年龄结构呈衰退型，个体数量主要集中在小树(IV龄段)，幼龄级株数和老龄级株数匮乏；长果安息香种群在进入生理死亡年龄前有2个死亡高峰，第1个峰值产生于幼树(II、III龄段)，主要原因是种内和种间竞争(主要是光照)，第2个峰值产生于中树长成大树阶段(V、VI龄段)，除种内、种间对环境的竞争外，生长地土层浅薄、大树倒伏及人为砍伐亦加剧了该峰值的产生；种群整体呈聚集分布类型，小树向中树、大树变化过程表现出聚集分布向随机分布转变，导致长果安息香濒危的主要原因是种子萌发率极低、种群竞争能力较差以及人为干扰等。  相似文献   

Environmental stress response limits microbial necromass contributions to soil organic carbon     

《Soil biology & biochemistry》2015

The majority of dead organic material enters the soil carbon pool following initial incorporation into microbial biomass. The decomposition of microbial necromass carbon (C) is, therefore, an important process governing the balance between terrestrial and atmospheric C pools. We tested how abiotic stress (drought), biotic interactions (invertebrate grazing) and physical disturbance influence the biochemistry (C:N ratio and calcium oxalate production) of living fungal cells, and the subsequent stabilization of fungal-derived C after senescence. We traced the fate of ¹³C-labeled necromass from ‘stressed’ and ‘unstressed’ fungi into living soil microbes, dissolved organic carbon (DOC), total soil carbon and respired CO₂. All stressors stimulated the production of calcium oxalate crystals and enhanced the C:N ratios of living fungal mycelia, leading to the formation of ‘recalcitrant’ necromass. Although we were unable to detect consistent effects of stress on the mineralization rates of fungal necromass, a greater proportion of the non-stressed (labile) fungal necromass C was stabilised in soil. Our finding is consistent with the emerging understanding that recalcitrant material is entirely decomposed within soil, but incorporated less efficiently into living microbial biomass and, ultimately, into stable SOC.  相似文献   

Short‐term releases of CO2 from newly mixed biochar and calcareous soil          下载免费PDF全文

R. Cardelli  M. Becagli  F. Marchini  A. Saviozzi 《Soil Use and Management》2016,32(4):543-545

The work aimed to quantify native organic C mobilized in one calcareous soil in the 21 days after addition of biochar at a range of large to very large applications. The experiment was carried out in unplanted microcosms, and CO₂ flux was used as a measure of net mineralization. A rapid methodological approach, which does not require ¹³C as a tracer, was used to assess any priming effects induced by the biochar. The amount of CO₂‐C mobilized was small relative to the amount of biochar C and proportional to the amount of the biochar added. The additional CO₂‐C was similar to the content of the water‐soluble organic carbon in the biochar added with each application. No interaction with native soil C, that is priming effect, was observed.  相似文献   

Contribution of Different Organs to Grain Filling in Durum Wheat under Mediterranean Conditions I. Contribution of Post‐Anthesis Photosynthesis and Remobilization          下载免费PDF全文

O. Merah  P. Monneveux 《Journal of Agronomy and Crop Science》2015,201(5):344-352

Under Mediterranean conditions, drought affects cereals production principally through a limitation of grain filling. In this study, the respective role of post‐anthesis photosynthesis and carbon remobilization and the contribution of flag leaf, stem, chaff and awns to grain filling were evaluated under Mediterranean conditions in durum wheat (Triticum turgidum var. durum) cultivars. For the purpose, we examined the effects of shading and excision of different parts of the plant and compared carbon isotope discrimination (Δ) in dry matter of flag leaf, stem, chaff, awns and grain at maturity and in sap of stem, flag leaf, chaff and awns, this last measurement providing information on photosynthesis during a short period preceding sampling. Source–sink manipulations and isotopic imprints of different organs on final isotope composition of the grain confirmed the high contribution of both carbons assimilated by ears and remobilized from stems to grain filling, and the relatively low contribution of leaves to grain filling. Grain Δ was highly and significantly associated with grain yield across treatments, suggesting the utilization of this trait as an indicator of source–sink manipulations effects on grain yield. Chaff and awns Δ were better correlated with grain Δ than stem and leaf Δ, indicating that chaff were more involved in grain filling than other organs. Moreover, in chaff, sap Δ was highly significantly correlated with dry matter Δ. These results suggest the use of Δ for a rapid and non‐destructive estimation of the variation in the contribution of different organs to grain filling.  相似文献   

Reconstructing mole tunnels using frequency-domain ground penetrating radar     

《Applied soil ecology》2014

The European mole (Talpa europaea L.) inhabits an underground tunnel system whereby the density, extent and condition of the subsurface tunnels are indicative of its activity. Currently, no survey method was able to reveal the spatial extent and condition of the mole's tunnel network. Frequency-domain ground penetrating radar (GPR) was evaluated on its potential to image these shallow tunnel systems. This technique allows for a non-invasive, high-resolution mapping of the subsurface. We examined the effectiveness of this GPR system for delineating the mole's tunnel network. The integration of different depth slices allowed a detailed overview of the tunnel system. Automatic feature recognition on these GPR images was proven valuable for the detection and representation of the mole tunnels. The GPR survey proved successful in mapping the mole's tunnel network, which facilitates the interpretation and characterization of the mole's living environment. This can be linked to the occurrence of earthworms, as the principle food source of the moles, which regulate important ecosystem processes within the soil. This offers new perspectives for the understanding of the mole's habitat.  相似文献   

杉木老龄林群落的种-多度关系研究     

蔡锰柯  刘圣恩  林开敏  赵长存  郑文辉  何宗明  郭玉硕 《热带作物学报》2015,36(3):617-622

以杉木老龄林群落为研究对象,结合对数级数和对数正态分布模型,建立3 600 m2的大样地分析杉木老龄林群落的种-多度关系。结果表明:样方的平均物种数和个体数分别为6.86种和35.75株,各样方的物种数及个体数存在极显著正相关关系,说明杉木老龄林群落中生境空间对物种个体的承载能力,还未限制其物种数量。个体数-种序(p>0.05)和频度-种序(p>0.05)的分布曲线均符合对数级数分布;对数正态分布模型则能够较好拟合个体数-种序(p>0.05)的分布曲线,但频度-种序(p<0.05)的分布曲线则不适合用该模型来解释。随着尺度的增加,物种数和个体数的变异系数、二者间的相关性及物种数的方差逐步下降,个体数的方差却呈上升的趋势。  相似文献   

Soil organic carbon stock variability in the Northern Gangetic Plains of India: interaction between agro‐ecological characteristics and cropping systems          下载免费PDF全文

V. K. Singh  M. Rani  B. S. Dwivedi  S. K. Singh  V. K. Gupta  K. Majumdar  R. P. Mishra 《Soil Use and Management》2015,31(4):461-473

Soil organic carbon (SOC) content and its spatial distribution in the Northern Gangetic Plain (NGP) Zone of India were determined to establish the cause–effect relationship between agro‐ecological characteristics, prevailing crop management practices and SOC stock. Area Spread Index (ASI) approach was used to collect soil samples from the NGP areas supporting predominant cropping systems. Exponential ordinary kriging was found most suitable geo‐statistical model for developing SOC surface maps of the NGP. Predicted surface maps indicated that 43.7% area of NGP had 0.5–0.6% SOC, while the rest of the area was equally distributed with high (0.61–0.75%) and low (< 0.5%) SOC content levels. Averaged across cropping systems, maximum SOC content was recorded in Bhabar and Tarai Zone (BTZ), followed by Central Plain Zone (CPZ), Mid‐Western Plain Zone (MWPZ), Western Plain Zone (WPZ) and South‐Western Plain Zone (SWPZ) of the NGP. The SOC stock was above the optimum threshold (> 12.5 Mg/ha) in 97.8, 57.6 and 46.4% areas of BTZ, CPZ and MWPZ, respectively. Only 9.8 and 0.4% area of WPZ and SWPZ, respectively, had SOC stock above the threshold value. The variation in SOC stock was attributed largely to carbon addition through recycling of organic sources, cropping systems, tillage intensity, crop or residue cover and land‐use efficiency, nutrient‐use pattern, soil texture and prevailing ecosystem. Adoption of conservation agriculture, balanced use of nutrients, inclusion of legumes in cropping systems and agro‐forestry were suggested for enhancing SOC stock in the region.  相似文献