Soil organic matter in water-stable aggregates under different soil management practices in a productive vineyard

In a productive vineyard, the influence of different soil management practices on carbon sequestration and its dynamic in water-stable aggregates of Rendzin Leptosol was studied. In 2006, an experiment of different management practices in a productive vineyard was established in the locality of Nitra-Dra?ovce, in the Nitra winegrowing area of Slovakia. The following treatments were established: (1) control (grass without fertilization); (2) T (tillage); (3) T + FM (tillage + farmyard manure); (4) G + NPK3 (grass + NPK 120–55–195 kg ha^?1); and (5) G + NPK1 (grass + NPK 80–35–135 kg ha^?1). The results showed that the lowest soil organic matter content (9.70 g kg^?1) in water-stable microaggregates was determined in G + NPK3, as well as in T. However, the highest soil organic matter content in the highest size fractions of water-stable macroaggregates (>5 mm) was observed in T + FM (19.7 g kg^?1). The highest value for carbon sequestration capacity in water-stable microaggregates was observed in the ploughed farmyard manure treatment. However, the control treatment showed the highest values for carbon sequestration capacity in water-stable macroaggregates, including agronomically favourable size fractions (0.5–3 mm). In all soil management practices under a productive vineyard the most intensive changes in the soil organic matter content were observed in the highest size fractions (>3 mm) of water-stable macroaggregates.     

大兴安岭南部丘陵半干旱农区系统功能与系统生产力分析——以大沟坝乡为例

通过大坝沟乡农业生态系统的能量与物质的投入产出分析,评价系统的功能、结构特征,探讨该地区增强系统功能、提高系统生产力的有效措施。     

烟台市土地利用变化及其驱动力分析

综合改革开放20多年来烟台市农村社会经济统计资料、土地概查、土地详查等资料结合实地调查研究揭示了该市土地利用的动态变化信息,分析了烟台市土地利用的数量变化和空间特征。结果表明：①20多年来,烟台市的非农建设用地显著增加,耕地数量呈明显的波动减少趋势。②经济发展、人口增长和政策是烟台市土地利用变化的主要驱动力。     

Effect of acidic deposition on hybrid poplar- primary or predisposing stress?

Our research examined the role of acidic deposition as a primary, or predisposing, stress on 8–12 week old cuttings of hybrid poplar (Populos deltoides x nigra). Firstly, we examined the role of acidic deposition as a primary stress in terms of physiological indicators (gas exchange, chlorophyll concentrations, chlorophyll-a fluorescence). Our results suggest that levels of acid precipitation of > pH 3.5 did not act as a primary stress. Secondly, we hypothesized that acidic deposition could act by making trees more susceptible to drought. An acid treatment exposure regime was followed by 3–4 days of drought stress in a controlled environment. Preexposure to acidic deposition did not increase the degree, or rate of appearance, of water stress as indicated by predawn xylem pressure potentials and leaf conductances. Examination of cuticular water loss from excised leaves suggested that this parameter was insensitive to acidic deposition from pH 3.0 to 5.5.     

Environmental controls on photosynthetic production and ecosystem respiration in semi-arid grasslands of Mongolia

The Mongolian steppe zone comprises a major part of East Asian grasslands. The objective of this study was to separately evaluate the quantitative dependencies of gross primary production (GPP) and ecosystem respiration (R_eco) on the environmental variables of temperature, moisture, radiation, and plant biomass in a semi-arid grassland ecosystem. We determined GPP and R_eco using transparent and opaque closed chambers in a grassland dominated by Poaceae species in central Mongolia during five periods: July 2004, May 2005, July 2005, September 2005, and June 2006. Values of GPP were linearly related to live aboveground biomass (AGB) enclosed by the chamber. The amount of GPP per unit ground area differed among the study periods, whereas GPP normalized by the amount of AGB did not differ significantly among the periods, suggesting that plant production per unit green biomass did not depend on the phenological stage. GPP/AGB fit well a rectangular hyperbolic light–response curve for all the study periods. When the air and soil were dry, considerable reduction in GPP was observed. The GPP/AGB ratio was also expressed as individual functions of air temperature, vapor pressure deficit, and volumetric soil water content. R_eco was exponentially related to the soil temperature and the relationship was modified by soil moisture. The amount of R_eco and its temperature sensitivity (Q₁₀) declined with decreasing soil moisture. Sharp increases of R_eco after rainfall events were observed. The values of R_eco, even including the rain-induced pulses, were expressed well as a bivariate function of soil temperature and soil moisture near the soil surface.     

浅谈市政道路石灰土基层施工

笔者从石灰土在道路施工中的重要性出发,分析市政道路石灰土基层施工的前期准备工作,并介绍了市政道路石灰土基层施工工艺流程,最后分析了特殊季节道路石灰土基层施工的注意事项。     

多花黑麦草的引种及其生产性能

1997-2000年对多花黑麦草在贵州喀斯特地区的引种及其生产性能进行了研究.经品比试验表明,阿倍德黑麦草生长势好,分蘖能力强,产草量最高,达6 710.29kg/667m2,生产及科研利用价值较高,经提纯复壮,定向培育,获得高产优质新品系贵草1号多花黑麦草,该品系农艺性状稳定,生产性能突出,种子产量稳定在50kg/667m2以上,具有较好的推广前景.     

后官湖地区NPP的计算及分析

基于植物生理生态学特点与水热平衡关系的植物净第一生产力模型对后官湖地区的自然植被第一生产力进行了计算和分析,结果表明,农田植被的净第一生产力最高,林地次之平,湖泊湿地最低,平均净第一生产力分别为983.36、172.24、45.01g/（m2·年）。研究区平均净生产力为1200.61g/（m2·年）,接近温带阔叶林的平均净生产力[1200.00g/（m2·年）],稍高于武汉地区的本底值1171.60g/（m2·年）,表明后官湖地区的生产系统恢复稳定性及自然系统恢复和调控能力较强,生态系统处于良性循环状态。