Using plant community uniqueness and floristic quality assessment in management decision-making in an urban park setting

With the densification of cities, it is imperative to identify urban ecosystems that should be protected or restored. We aimed to determine the conservation and restoration needs in a large urban park (1,35 km²) in Quebec City (Canada), based on site history, current species richness, floristic uniqueness, and floristic quality assessment of its diverse ecosystems: forest, swamp, wooded peatland, open peatland, and marsh. We evaluated the cover of all vascular species in 70 plots (400 m²) and assessed 18 environmental variables. We found that forest and swamp plots were the richest while peatland plots were the poorest, with marsh plots showing intermediate values. Ecological uniqueness (LCBD) was not correlated with richness (ρ = 0.17; p > 0.05), with marsh and peatland plots showing the highest and lowest uniqueness, respectively. With a regression tree, we identified canopy openness as the most influential variable explaining plot uniqueness across all ecosystems, especially in the peatland, indicating that future recreational development should be avoided in open ecosystems. By plotting ecological uniqueness (LCBD) with tolerance to disturbance (Mean C) values, we identified areas that could benefit from conservation or restoration, and areas that could sustain future development for recreational use. For each area, floristic composition, site characteristics, and past land-use history were investigated further to identify appropriate actions. The open peatland was identified as the main conservation priority, but actions will be needed to limit rapid tree encroachment. Three marshes were identified as areas that would floristically benefit from restoration actions. Still, since they also act as natural retention basins hosting species adapted to the soil conditions, we suggested monitoring the expansion of exotic and invasive species. Approaches developed and lessons learned from this project will serve as guidelines for municipalities aiming to implement a restoration and management plan in urban parks.     

酸性土壤有效砷提取方法研究

采用0.5mol·L-1NaHCO3(pH8.5),0.5mol·L-1NaH2PO4和0.1mol·L-1HCl等3种浸提剂,对福建省酸性水稻土和酸性菜地土壤有效砷的提取效果以及相关的提取条件进行了研究。结果表明,3种浸提剂所提取的土壤有效砷与作物可食用部分砷含量之间均存在显著相关,其中0.5mol·L-1NaH2PO4提取的有效砷与糙米和蔬菜地上部砷含量的相关性最高,相关系数分别是0.628和0.824,是三者中最佳的浸提剂。对NaH2PO4的提取条件的研究表明,在15∶1的液土比条件下以250r·min-1的速度振荡120min是最佳的酸性土壤有效砷的提取方法。     

攀西干旱干热河谷退耕还林立地类型的划分及经营模式探讨

四川攀西干旱干热河谷面积巨大，气候类型多样，自然地貌复杂，该区有500万亩耕地将退耕还林，通过对该区自然地理条件调查研究，按照水、热、土等因子将该区划分为四大类型区，即：高海拔干冷区、中海拔干凉区、中低海拔干暖区、低海拔干热区；建立了干旱干热河谷退耕还林地的立地质量评价体系。并根据立地条件和经营条件对该区的退耕还林模式进行了探讨。     

Persistence of tebufenozide in aquatic ecosystems under laboratory and field conditions

The persistence and dissipation behaviour of tebufenozide, an ecdysone agonist, were investigated: (1) under laboratory conditions in aquatic models set up in glass aquaria, and (2) under field conditions in in-situ aquatic enclosures deployed in a mixed-wood boreal forest lake. Two models were set up in the laboratory study (Study I), which was conducted at constant conditions of temperature, water pH and photoperiod. In Model I, partitioning of tebufenozide from sediment, treated at a concentration of 1400 μg kg^-1, into untreated water was examined. The results showed that the chemical moved very little from the treated sediment into water. The concentration in sediment and water decreased gradually during the 90-day incubation period. Tebufenozide disappeared faster from the top layer of sediment than from the middle and bottom layers. The half-lives of disappearance were 64 days for the top layer but >90 days for the middle and bottom layers respectively. In Model II, partitioning from water, treated at a concentration of 350 μg litre^-1, into untreated sediment was investigated. The results showed that the chemical moved from treated water into sediment due to adsorption. Little vertical downward movement of the adsorbed residues from the top layer of sediment occurred into layers beneath. The adsorbed residues were also not released readily back into water. The concentration in water and sediment decreased gradually during the 90-day incubation period. The half-life of dissipation from water was 67 days. The field microcosm study (Study II), conducted under fluctuating conditions of temperature, water pH and photoperiod, involved application of tebufenozide onto aquatic enclosures at four concentrations of 0·05, 0·10, 0·26 and 0·5 mg litre^-1. This study also showed that the chemical moved downwards from the applied location and was adsorbed onto sediment. The chemical persisted longer in Study II than in Study I. Tebufenozide, being photo-labile, probably degraded faster after constant exposure to light in Study I than after exposure to fluctuating light in Study II. At 90 days after treatment in Study I, only about 55% of the applied material persisted in the sediment, and there was little accumulation. In Study II, the material not only persisted but also was accumulated in the sediment, since at 92 days post-treatment the residues were about 25 times higher than the applied concentration level. Residues in water also decreased more rapidly in Study I than in Study II, because the concentration at 90 days post-treatment was about 41% of the applied value. In Study II, however, about 65% of the applied chemical persisted in water at 92 days post-treatment. While the long persistence of tebufenozide in both the laboratory and field studies was attributable to its low vapour pressure, low water solubility, high octanol/water partition coefficient etc., the differences in the persistence characteristics observed in the two studies were due to the fluctuating environmental conditions and water pH encountered in the field study, compared with the constant environmental conditions and water pH utilized in the laboratory study. © 1997 SCI.     

磷、钾对番茄可溶性碳水化合物分配的影响

以番茄苗为试验材料,研究了不同浓度磷、钾对番茄植株可溶性碳水化舍物分配的影响。结果表明：磷、钾亏缺处理45d后,与正常磷、钾处理相比,磷亏缺的植株冠根比下降,而钾亏缺的植株冠根比则上升。钾亏缺的植株叶片中,蔗糖、还原糖和总可溶性糖含量均表现为上升,根中则表现为下降。磷亏缺的植株叶片中,蔗糖、还原糖和总可溶性糖含量基本不变,而在根中则表现为不同程度的增加。在叶和根的总可溶性糖中,钾亏缺和磷亏缺的植株,根部总可溶性糖所占的比例分别为10．71％和45．65％,两者的对照分别为28．63％和33．11％。上述结果表明,钾和磷在光合产物的转运中所起的作用不同,植株中营养元素亏缺不同,干物质在不同部位的分配也不同。     

黄瓜自交系低温弱光耐受性快速筛选平台的建立

黄瓜对低温和弱光的耐受性是两个相对独立的性状,需要单独进行评价.设计了以叶面积增长量为主要性状指标的弱光(或弱光 偏低温)耐受性的评价指标体系和以冷害指数作为临界低温耐受性评价指标的快速筛选体系,两者可复合实施.     

大黄素甲醚、大黄酸的研究进展

2014年世界卫生组织首份全球抗菌素耐药报告显示全世界面临严重的公共卫生威胁,2021年农业农村部制定了《全国兽用抗菌药使用减量化行动方案》(2021-2025),从国家层面实施综合治理策略和措施,鼓励替代抗菌药物的研制和创新。大黄素甲醚、大黄酸作为植物蒽醌类有效成分,具有抗微生物、抗炎、抗氧化、神经保护等药理作用,但对其抗菌、抗病毒、抗炎症相关的作用机制和产业化工艺缺少详细报道。本文对国内外已经发表的专利文献、期刊文献进行综述,总结其抗菌、抗病毒、抗炎作用机制及其生产工艺,以期为进一步开发利用提供科学支撑。     

农民持续使用农业科教应用程序意愿的影响因素研究

从技术性能、服务效果、环境条件等维度构建农民持续使用农业科教应用程序意愿模型,依据422名湘农科教云应用程序农民用户调查数据开展研究。结果显示,除设施条件影响不显著外,满意度、系统质量、感知易用性、感知有用性、服务质量、期望确认度、社群影响等正向显著影响农民持续使用意愿,感知风险则负向显著影响。对此,应优化科技服务质量、加强平台安全防控、提升农民数字素养和加大宣传推广力度,促进农业科教应用程序高质量发展,增强农民持续使用意愿。     

饲料蛋白能量比对红鳍东方鲀幼鱼的生长性能、饲料利用和体组成的影响

为探求红鳍东方鲀(Takifugu rubripes)幼鱼饲料的最适蛋白质能量比,以鱼粉和豆粕作为主要蛋白源,鱼油和豆油作为主要脂肪源,配制粗蛋白含量分别为36%、42%和48%,粗脂肪含量分别为8%、12%和16%,蛋能比为17.06~24.20 mg/kJ的9组饲料。投喂初始体重为14.95 g的红鳍东方鲀幼鱼56 d。结果显示,由双因素分析方法得出,饲料的蛋白水平、脂肪水平和蛋能比水平均可显著影响红鳍东方鲀的终末体重、特定生长率(SGR)和饲料效率(FE),且饲料蛋白为36%时,显著低于42%和48%组,但与饲料蛋白为42%和48%组之间相比无显著差异。在饲料脂肪为8%时,显著低于12%组,与饲料脂肪为12%与16%组之间相比无显著差异。此外,饲料的蛋白和脂肪水平对红鳍东方鲀生长和饲料利用的相关指标均无显著的交互作用(P>0.05)。由单因素方差分析得出,终末体重、FE、SGR均是Diet8(48/12)蛋白水平为48%、脂肪水平为12%处理组最高,显著高于Diet1(36/8)蛋白水平为36%和脂肪水平为8%处理组、Diet2(36/12)蛋白水平为36%和脂肪水平为12%处理组、Diet3(36/16)蛋白水平为36%和脂肪水平为16%处理组(P<0.05)与Diet4(42/8)蛋白水平为48%和脂肪水平为8%处理组、Diet5(42/12)蛋白水平为42%和脂肪水平为12%处理组、Diet6(42/16)蛋白水平为42%和脂肪水平为16%处理组、Diet7(48/8)蛋白水平为48%、脂肪水平为8%处理组之间相比无显著差异(P>0.05)。因此,根据研究结果综合考虑生长性能及蛋白质节约效应,红鳍东方鲀幼鱼的最适蛋白水平为42%,脂肪水平为12%,蛋能比为20.75 mg/kJ。     

不同脂肪(能量)蛋白比饲料对梭鲈幼鱼生长的影响

比较了5种不同脂肪(能量)蛋白比的配合饲料对初始平均体重(7.75±1.17)g梭鲈幼鱼生长性能的影响。结果表明,投喂不同脂肪蛋白水平的饲料,以能量蛋白比为45.94kJ/g试验组的生长速度最快[SGR为(2.86±0.17)%/d]、饲料系数最低(FCR为1.57±0.12)、蛋白质沉积率和能量保留率最大,分别为98.44%±2.38%和30.88%±3.83%;以饲料中蛋白质含量、脂肪含量为变量因子,以梭鲈幼鱼的特定生长率、蛋白质沉积率和能量保留率为指标,通过二元二次回归方程得出梭鲈最大生长速度时饲料中蛋白质含量为39.80%,脂肪含量为8.79%,总能为18.53MJ/kg,脂肪蛋白比为0.22,能量蛋白比为46.56kJ/g;梭鲈获得最大的蛋白质沉积率时,饲料蛋白质含量为38.76%,脂肪含量为9.18%,总能为18.65MJ/kg,脂肪蛋白比为0.24,能量蛋白比为48.12kJ/g;梭鲈获得最大的能量保留率时饲料蛋白质含量为38.55%,脂肪含量为9.45%,总能为18.72MJ/kg,脂肪蛋白比为0.25,能量蛋白比为48.56kJ/g;饲料中脂肪水平的增加可以降低鱼类耗能时对蛋白质的需求量,表...