氮素分期优化管理方法对冬小麦籽粒品质的影响

采用田间试验,对氮素分期优化管理方法对小麦籽粒品质的影响进行了研究,以期为高产、优质、资源高效、环境保护等多重目标并重的养分资源优化管理提供理论依据.结果表明:氮素供应量最优的处理(冬小麦返青期氮素供应量即0～60 cm土壤Nmin+肥料氮为90 kg/hm2,拔节期追氮量即施用肥料氮30 kg/hm2)的冬小麦籽粒产量和其他氮素供应量处理没有显著差异;氮素供应量最优的处理冬小麦籽粒的粗蛋白和面筋含量显著低于在返青期和拔节期供氮量都高的处理(冬小麦返青期氮素供应量即0～60 cm土壤Nmin+肥料氮为150kg/hm2、拔节期追氮量即施用肥料氮90kg/hm2),但与其他处理相比差异不显著;以高产、资源高效和环境保护为前提的冬小麦氮肥分期优化施用量获得了最高产量的同时兼具较好的小麦籽粒品质.     

鼎湖山季风常绿阔叶林各层次优势种热值研究

探讨鼎湖山南亚热带季风常绿阔叶林不同层次优势植物热值一般规律,可为该群落能量特征和生态效率研究提供基础资料和科学依据. 2002年用PARR 1281型氧弹热值仪测定了该群落不同层次21种优势植物不同器官(部位)热值. 结果表明, 季风常绿阔叶林各优势种的平均干重热值在15.92～19.66 kJ/g间,乔木1层干重热值以厚壳桂最高, 乌榄最低; 乔木2层华润楠最高, 云南银柴最低; 层间藤本植物白背瓜馥木和杖枝省藤分别为19.73和18.19 kJ/g; 灌木层干重热值最高仍为厚壳桂, 最低为云南银柴; 草本层植物干重热值在15.92～17.52 kJ/g之间. 各层优势种平均干重热值和去灰分热值都表现为: 层间藤本＞乔木1层＞乔木2层＞灌木层＞草本层. 植物器官去灰分热值存在差异, 乔木1层中锥栗、荷木树皮及厚壳桂、乌榄树叶最高, 乔木2层中云南银柴根最高, 层间植物叶＞干＞根, 草本植物是地上部分＞地下部分; 同种植物(厚壳桂或云南银柴)在不同层次中的去灰分热值没有明显差别, 器官生长的年龄(或直径)对去灰分热值有影响, 随年龄增大, 去灰分热值有减少趋势.      

Self‐Reported Acute Health Effects and Exposure to Companion Animals

To understand the etiological burden of disease associated with acute health symptoms [e.g. gastrointestinal (GI), respiratory, dermatological], it is important to understand how common exposures influence these symptoms. Exposures to familiar and unfamiliar animals can result in a variety of health symptoms related to infection, irritation and allergy; however, few studies have examined this association in a large‐scale cohort setting. Cross‐sectional data collected from 50 507 participants in the United States enrolled from 2003 to 2009 were used to examine associations between animal contact and acute health symptoms during a 10–12 day period. Fixed‐effects multivariable logistic regression estimated adjusted odds ratios (AORs) and 95% confident intervals (CI) for associations between animal exposures and outcomes of GI illness, respiratory illness and skin/eye symptoms. Two‐thirds of the study population (63.2%) reported direct contact with animals, of which 7.7% had contact with at least one unfamiliar animal. Participants exposed to unfamiliar animals had significantly higher odds of self‐reporting all three acute health symptoms, when compared to non‐animal‐exposed participants (GI: AOR = 1.4, CI = 1.2–1.7; respiratory: AOR = 1.5, CI = 1.2–1.8; and skin/eye: AOR = 1.9, CI = 1.6–2.3), as well as when compared to participants who only had contact with familiar animals. Specific contact with dogs, cats or pet birds was also significantly associated with at least one acute health symptom; AORs ranged from 1.1 to 1.5, when compared to participants not exposed to each animal. These results indicate that contact with animals, especially unfamiliar animals, was significantly associated with GI, respiratory and skin/eye symptoms. Such associations could be attributable to zoonotic infections and allergic reactions. Etiological models for acute health symptoms should consider contact with companion animals, particularly exposure to unfamiliar animals. Prevention of pet‐associated zoonotic diseases includes commonsense measures such as hand‐washing, but are often overlooked by pet owners and non‐pet owners alike.     

Global development and the future of the protected area strategy

Land protection has become increasingly common, and global land protection is now greater than 12%. Prediction of future protected area expansion are uncertain, and depend on understanding the factors that have to date explained the historical pattern and geographic variation in protected area (PA) establishment. We test four major perspectives on factors limiting or facilitating PA creation, differentiating between strict PAs and multiple-use PAs where some resource extraction is permitted. Richer countries had a greater amount of land protection and were more likely to create strict PAs, supporting the view of land protection as an economic amenity, although the magnitude of this effect declines in recent decades. There are also significant differences in amount of protection by political structure, with independent countries tending to protect more land, and education, with countries with high levels of primary education tending to protect more. However, countries with substantial previous protection tend to do less protection and create proportionally fewer strict and more multiple-use PAs. Scenarios of future socioeconomic and political conditions suggest that on balance the amount of protection should increase in many countries, driven by economic prosperity, and by 2030 global land protection is forecast to reach 15–29%. The limiting factor in land protection varies among countries, and sub-Saharan African countries in particular will remain a very hard place for land protection because of low per-capita GDP. Overall, however, more land protection may occur in the next 20 years than has occurred in the previous 20 years.     

大肠酶对猪饲料酶水解物能值的影响及与非淀粉多糖组分的关系

【目的】研究大肠酶对单胃动物仿生消化系统测试猪饲料原料的体外干物质消化率（DMD）和酶水解物能值（EHGE）的影响,并分析不同大肠酶条件下非淀粉多糖（NSP）组分与DMD和体外总能消化率（GED）的关系,为完善体外模拟胃-小肠-大肠三步消化方法提供参考依据。【方法】采用单因素完全随机设计,共设4个处理,在单胃动物仿生消化系统模拟饲料原料胃和小肠消化后,分别使用对照组（去离子水）、纤维素酶、Viscozyme酶和仿生酶（由纤维素酶、木聚糖酶、β-葡聚糖酶和果胶酶组成）模拟大肠阶段的消化。每个处理设5个重复,每个重复1根消化管,分别测定玉米、大豆粕、小麦麸、玉米DDGS、苜蓿草粉和大豆皮的DMD、GED和EHGE。并使用乙酸酐衍生化气相色谱法测定6种饲粮原料NSP含量和组分。分析饲料原料NSP组分与DMD及GED的相关关系。 【结果】（1）在对照组中,玉米的DMD最高,达到了81.51 %,相应的EHGE为15.39 MJ·kg^-1,而大豆皮的DMD最低,只有10.60 %,相应的EHGE只有2.42 MJ·kg^-1。（2）3种模拟大肠酶均显著提高了玉米、大豆粕和大豆皮的DMD（P＜0.01）,提高了大豆粕和大豆皮的EHGE（P＜0.01）。但纤维素酶作用下苜蓿草粉、玉米DDGS的DMD和EHGE与对照组差异不显著,Viscozyme酶作用下小麦麸、玉米DDGS的DMD和EHGE与对照组差异不显著（P＞0.05）。仿生酶显著提高了6种饲料原料的DMD（P＜0.01）,显著提高了除玉米DDGS外的其他5种饲料原料的EHGE（P＜0.01）。（3）不同的大肠酶对不同饲料原料体外消化率的提升程度不同。在6种原料中,纤维素酶对小麦麸的DMD和EHGE提升程度最高,分别达到了5.89 %和1.03 MJ·kg^-1,而只使大豆粕的DMD和EHGE提高了1.26 %和0.36 MJ·kg^-1;Viscozyme酶对大豆皮体外消化率的提升程度最高,分别使其DMD和EHGE提高6.01%和1.02 MJ·kg^-1。仿生酶对小麦麸的DMD和EHGE的提升程度最高,达到了6.59%和1.37 MJ·kg^-1。（4）6种饲料原料的可溶性非淀粉多糖（SNSP）的含量均低于不溶性非淀粉多糖（INSP）,玉米的总非淀粉多糖（TNSP）含量最低（8.59%）,大豆皮的TNSP含量最高（75.72%）,各原料的NSP主要由阿拉伯糖、木糖、甘露糖和葡萄糖组成,但不同原料中4种单糖含量存在差异。（5）6种饲料原料的SNSP、INSP以及TNSP含量与DMD、GED均呈显著的负相关（P＜0.05）。仿生酶作用下DMD与TNSP含量的相关性（R ²=0.95, P＜0.01）高于纤维素酶（R ²=0.94, P＜0.01）和Viscozyme酶（R ²=0.93, P＜0.01）。同时,仿生酶作用下GED与TNSP含量的相关性（R ²=0.89, P＜0.01）也高于纤维素酶（R ²=0.86, P＜0.01）和Viscozyme酶（R ²=0.81, P＜0.01）。【结论】仿生酶在体外模拟猪大肠消化过程中,对饲料的消化作用优于纤维素酶和Viscozyme酶,可作为单胃动物仿生消化系统体外模拟猪消化中大肠阶段的模拟消化酶。     

Water-use efficiency in response to simulated increasing precipitation in a temperate desert ecosystem of Xinjiang,China

Water-use efficiency(WUE) is a key plant functional trait that plays a central role in the global cycles of water and carbon. Although increasing precipitation may cause vegetation changes, few studies have explored the linkage between alteration in vegetation and WUE. Here, we analyzed the responses of leaf WUE, ecosystem carbon and water exchanges, ecosystem WUE, and plant community composition changes under normal conditions and also under extra 15% or 30% increases in annual precipitation in a temperate desert ecosystem of Xinjiang, China. We found that leaf WUE and ecosystem WUE showed inconsistent responses to increasing precipitation. Leaf WUE consistently decreased as precipitation increased. By contrast, the responses of the ecosystem WUE to increasing precipitation are different in different precipitation regimes: increasing by 33.9% in the wet year(i.e., the normal precipitation years)and decreasing by 4.1% in the dry year when the precipitation was about 30% less than that in the wet year.We systematically assessed the herbaceous community dynamics, community composition, and vegetation coverage to explain the responses of ecosystem WUE, and found that the between-year discrepancy in ecosystem WUE was consistent with the extent to which plant biomass was stimulated by the increase in precipitation. Although there was no change in the relative significance of ephemerals in the plant community, its greater overall plant biomass drove an increased ecosystem WUE under the conditions of increasing precipitation in 2011. However, the slight increase in plant biomass exerted no significant effect on ecosystem WUE in 2012. Our findings suggest that an alteration in the dominant species in this plant community can induce a shift in the carbon-and water-based economics of desert ecosystems.     

Identifying the influence of urbanization on soil organic matter content and p H from soil magnetic characteristics

Soil magnetic characteristics are correlated with soil p H and organic matter content. Analyzing soil magnetic characteristics, organic matter content and p H can indirectly evaluate soil pollution caused by human activities. This study analyzed the soil magnetic characteristics, organic matter content and p H in surface soil samples from different land use types in Shihezi city, a newly and rapidly developing oasis city in Xinjiang of China. The aims of this study were to explore the possible relationships among the soil magnetic parameters and thereby improve the understanding of influence of urbanization on soil properties. Eighty surface soil samples at the depth of 0–10 cm were collected from 29 July to 4 August 2013. The results showed that the magnetic minerals in surface soil were dominated by ferromagnetic minerals. Spatially, the magnetic susceptibility(χLF), anhysteretic remanent magnetization susceptibility(χARM), saturation isothermal remanent magnetization(SIRM) and "soft" isothermal remanent magnetization(SOFT) were found to be most dominant in the new northern urban area B(N-B), followed by built-up areas(U), suburban agricultural land(F), and then the new northern urban area A(N-A). The values of χLF, χARM, SIRM and SOFT were higher in the areas with high intensities of human activities and around the main roads. Meanwhile, the property "hard" isothermal remanent magnetization(HIRM) followed the order of UN-BFN-A. Built-up areas had an average p H value of 7.93, which was much higher than that in the new northern urban areas as well as in suburban agricultural land, due to the increased urban pollutant emissions. The average value of soil organic matter content in the whole study area was 34.69 g/kg, and the values in the new northern urban areas were much higher than those in the suburban agricultural land and built-up areas. For suburban agricultural land, soil organic matter content was significantly negatively correlated with χLF, and had no correlation with other magnetic parameters, since the soil was frequently ploughed. In the new northern urban areas(N-A and N-B), there were significant positive correlations of soil organic matter contents with χARM, SIRM, SOFT and HIRM, because natural grasslands were not frequently turned over. For the built-up areas, soil organic matter contents were significantly positively correlated with χLF, χARM, SIRM and SOFT, but not significantly correlated with frequency-dependent susceptibility(χFD, expressed as a percentage) and HIRM, because the soil was not frequently turned over or influenced by human activities. The results showed that soil magnetic characteristics are related to the soil turnover time.     

Components,drivers and temporal dynamics of ecosystem respiration in a Mediterranean pine forest

To investigate the climate impacts on the different components of ecosystem respiration, we combined soil efflux data from a tree-girdling experiment with eddy covariance CO₂ fluxes in a Mediterranean maritime pine (Pinus pinaster) forest in Central Italy. 73 trees were stem girdled to stop the flux of photosynthates from the canopy to the roots, and weekly soil respiration surveys were carried out for one year. Heterotrophic respiration (R_H) was estimated from the soil CO₂ flux measured in girdled plots, and rhizosphere respiration (R_Ab) was calculated as the difference between respiration from controls (R_S) and girdled plots (R_H).Results show that the R_S dynamics were clearly driven by R_H (average R_H/R_S ratio 0.74). R_H predictably responded to environmental variables, being predominantly controlled by soil water availability during the hot and dry growing season (May–October) and by soil temperature during the wetter and colder months (November–March). High R_S and R_H peaks were recorded after rain pulses greater than 10 mm on dry soil, indicating that large soil carbon emissions were driven by the rapid microbial oxidation of labile carbon compounds. We also observed a time-lag of one week between water pulses and R_Ab peaks, which might be due to the delay in the translocation of recently assimilated photosynthates from the canopy to the root system. At the ecosystem scale, total autotrophic respiration (R_At, i.e. the sum of carbon respired by the rhizosphere and aboveground biomass) amounted to 60% of ecosystem respiration. R_At was predominantly controlled by photosynthesis, and showed high temperature sensitivity (Q₁₀) only during the wet periods. Despite the fact that the study coincided with an anomalous dry year and results might therefore not represent a general pattern, these data highlight the complex climatic control of the respiratory processes responsible for ecosystem CO₂ emissions.     

绿色GDP核算中森林保育土壤价值的研究进展

 森林资源是绿色GDP核算的重要内容,土壤保育是其最重要的环境服务功能之一,也是绿色GDP核算的重点和难点。在充分考虑森林生态价值特点的基础上,总结有关森林保育土壤价值的研究成果,将目前核算森林保育土壤价值的模型归纳为整体核算模型和累加核算模型2类。通过从价值核算及核算结果纳入绿色GDP2方面分析,认为在目前的核算中主要存在土壤侵蚀模型尚不完善、替代核算存在偏差、核算变量数据不精确、核算面积确定不准确、功能计量代替效益计量等问题。针对这些问题建议加强土壤侵蚀等相关领域研究、规范核算指标体系,并采取分区核算、个量分析及贴现的方法,运用3S等先进技术手段提高核算精度。同时,科学地界定绿色GDP的内涵,区分森林各项具体生态功能价值间的关系及在绿色GDP体系中的位置和作用,避免在核算中重复或缺漏。