意大利瓦勒拉尼整地系统与常规开沟犁整地效益对比分析

通过意大利瓦勒拉尼整地系统（由火车型犁和海豚型犁2种犁型构成,其中火车型犁近似水平沟式整地,海豚型犁近似大鱼鳞坑式整地）与常规开沟犁整地效益的对比试验,结果显示：同期覆土层（0～20 cm）的土壤含水量以瓦勒拉尼系统2种整地方式最高,是常规开沟犁整地的1.28倍和1.11倍。火车型犁整地的土壤容重为1.05 g/cm3,常规开沟犁整地为1.08 g/cm3,火车型犁整地后的土壤容重最小。瓦勒拉尼系统的火车型犁整地后的土壤毛管最大持水量是56.12%,远高于未整地的48.44%和普通犁整地的52.12%,分别是后两者的1.16倍和1.08倍。火车型犁整地后文冠果的地径达1.00 cm,是普通犁整地后地径0.42 cm的2.38倍;树高为0.93 m,是普通犁整地后树高0.53 m的1.75倍;保存率由59.30%提高至91.43%,提高了32.13个百分点;海豚型犁整地文冠果4年保存率则提高了13.42个百分点。     

国家中心城市基础设施承载力评价及障碍因素诊断

[目的]定量分析国家中心城市2006—2017年基础设施承载力的具体情况,为促进国家中心城市建设良性健康发展提供科学依据。[方法]选取2006—2017年国家中心城市基础设施承载力面板数据,从压力和状态两个层面构建城市基础设施承载力评价指标体系。运用熵权TOPSIS方法和障碍度模型对2006—2017年国家中心城市基础设施承载力和障碍因素进行评价和诊断,并基于基础设施承载力评价结果,定量测度基础设施承载力状况并诊断其障碍因子。[结果] 2006—2010年国家中心城市的基础设施承载力水平总体上大幅度提升,2011—2017年基础设施承载力的增长速度有所减缓,北京、上海、成都、郑州、西安的基础设施承载力大幅度提高,广州市的基础设施承载力改善幅度最小;随着国家中心城市的人口持续增加,基础设施的承载压力也持续增加,通过障碍度模型分析发现制约国家中心城市基础设施承载力的主要因素为人均绿地面积、人均家庭年生活用水量和城市移动电话普及率。[结论]随着中国经济的发展,中心城市对人口的虹吸作用越加强烈,人均绿地面积、城市移动电话普及率以及人均家庭年生活用水量可能与城市的经济与人口规模产生脱钩现象,无法满足人们日常的基础设施需求。     

基于InVEST模型的祁连山国家级自然保护区土壤保持现状与功能

运用InVEST模型,对甘肃祁连山自然保护区土壤保持现状与功能进行了定量评估,分析了不同土地利用、海拔高度、坡度以及土壤类型下的保土状况。结果表明:2015年甘肃祁连山自然保护区土壤侵蚀量与土壤保持量分别为1. 67×10^8t、4.21×10^8t。从侵蚀面积来看,保护区以微度和轻度侵蚀为主,占总面积的63.95%;虽草地的土壤保持能力弱于其他自然植被类型,但草地是土壤保持总量最高的土地利用类型;不同海拔梯度下的土壤保持总量随海拔增加呈现先增后减的趋势,保护区内海拔2 500~3 500 m的土壤保持功能最好;栗钙土的土壤保持量最高,黑毡土在草原土壤类型中土壤保持强度较低;坡度为15°~25°的区域土壤保持量最大,占土壤保持总量的31.93%;甘肃祁连山保护区生态系统减少泥沙淤积和减少土地废弃的价值分别为5. 76×10^8元和1. 44×10^8元,保护区内林草地保肥价值为9. 03×10^10元。     

Quantifying key model parameters for wheat leaf gas exchange under different environmental conditions

The maximum carboxylation rate of Rubisco(V_(cmax)) and maximum rate of electron transport(J_(max)) for the biochemical photosynthetic model, and the slope(m) of the Ball-Berry stomatal conductance model influence gas exchange estimates between plants and the atmosphere. However, there is limited data on the variation of these three parameters for annual crops under different environmental conditions. Gas exchange measurements of light and CO_2 response curves on leaves of winter wheat and spring wheat were conducted during the wheat growing season under different environmental conditions. There were no significant differences for V_(cmax), J_(max) or m between the two wheat types. The seasonal variation of V_(cmax), J_(max) and m for spring wheat was not pronounced, except a rapid decrease for V_(cmax) and J_(max) at the end of growing season. V_(cmax) and J_(max) show no significant changes during soil drying until light saturated stomatal conductance(gssat) was smaller than 0.15 mol m~(–2) s~(–1). Meanwhile, there was a significant difference in m during two different water supply conditions separated by gssat at 0.15 mol m~(–2) s~(–1). Furthermore, the misestimation of V_(cmax) and J_(max) had great impacts on the net photosynthesis rate simulation, whereas, the underestimation of m resulted in underestimated stomatal conductance and transpiration rate and an overestimation of water use efficiency. Our work demonstrates that the impact of severe environmental conditions and specific growing stages on the variation of key model parameters should be taken into account for simulating gas exchange between plants and the atmosphere. Meanwhile, modification of m and V_(cmax)(and J_(max)) successively based on water stress severity might be adopted to simulate gas exchange between plants and the atmosphere under drought.     

Cross‐linked polyacrylates in post‐mining substrates: persistence and effects on plant growth

Application of hydrophilic polymers composed of cross‐linked polyacrylate can improve soil water‐holding capacity and accelerate the restoration of post‐mining substrates. In this work, we studied the persistence of a polyacrylate polymer incorporated into a soil and its impact on plant nutrients at a reclamation site of former lignite mining in Lusatia (Germany). In contrast to autumn application, the incorporation of the polymer enhanced the sequestration of plant‐derived carbon in the soil, which was reflected by a significant increase in the concentration of a lignin marker. Attenuated total reflexion–Fourier transform infrared spectra (ATR‐FTIR) and total elemental contents in the applied polymer suggested an intensive cation exchange between the polymer framework and the soil‐forming substrate. In addition, there was an enrichment of carbonaceous material, which seems to reduce the swelling and thus the water‐holding capacity of the cross‐linked polyacrylate. Conversely, this process protected the polymer structure from rapid decomposition.     

A rapid extensigraph protocol for measuring dough viscoelasticity and mixing requirement

The extensigraph is particularly useful in characterizing dough viscoelastic properties; however, testing throughput for standard method is low due to the prerequisite for farinograph water absorption, long dough resting and milling to prepare large amounts of flour. Therefore, a rapid extensigraph method was developed that reduced sample size (165 g wheat) for milling and more than tripled throughput. Wheat is milled in Quadrumat Junior mill with a modified sieving system. The resulting flour (100 g) was mixed with a pin mixer at constant water absorption to allow the evaluation of wheat genotypes at the absorption level they are expected to perform. Dough was subsequently stretched by an extensigraph after 15 min of floor time and 30 min resting. Strong correlations for extensigram R_max (r > 0.93), extensibility (r > 0.64) and area (r > 0.88) were found for the proposed method compared to the standard method. Mixing parameters (time and energy) obtained during dough preparation provided further information about dough strength and mixing requirement. By significantly reducing sample size requirement and increasing testing throughput, this rapid extensigraph method can be widely adopted in milling and baking industry and meets the need for a fast evaluation of dough strength in breeding trials.     

Carrying capacity for finfish aquaculture. Part I—Near-field semi-analytic solutions

The ecosystem carrying capacity for aquaculture cage farming in South Australia is based on guidelines that the maximum feed rates (and farmed fish biomass) be determined such that the concentration c of a given dissolved nutrient does not exceed a prescribed value (say c_P). The problem then is one of relating the nutrient flux F, due to feeding, to the tracer concentration c. To this end the evolution of concentration is modelled using the depth-averaged advection–diffusion equation for a constant source flux F over a finite area cage (or lease) and for both constant and time dependent (tidal) velocities. The divergence theorem is applied to this equation to obtain a new scale estimate of the relation between the flux F and the maximum concentration c_max of a nutrient in the cage region: c_max ≈ F·T*, where T* is a time scale of cage “flushing” that involves both advection and diffusion. The maximum allowed nutrient flux F (and carrying capacity of fish biomass) can then be simply estimated from: F ≈ c_P/T*. New semi-analytic solutions of the advection–diffusion equation for a finite (cage) source are then derived to explore the physics of concentration evolution for constant and tidally varying currents, and to show that the estimate c_max ≈ F·T* is surprisingly robust and generally within 40% of the exact values for a wide set of advective/diffusive parameters. The results generally should find application in other finite source flux problems in the coastal oceans including desalination plants and waste water outfalls.     

基于P-S-R框架模型试点研究高寒地区生态承载力——以甘肃省迭部县为例

全面客观评价生态资源承载能力,进而为区域可持续发展提供理论依据。以甘肃省迭部县为例,首先,采用压力-状态-响应(P-S-R)模型构建生态承载力评估指标体系,运用层次分析法(Analytic Hierarchy Process,AHP)确定各指标权重,评估生态环境承载力现状;其次,在生态功能区层面对迭部县水源涵养功能及生物多样性功能进行评价;最后,对生态承载力状况进行成因解析。研究结果表明：（1）迭部县整体生态承载力得分为0.239,处于“较强”承载力状态,构成整体生态承载力的生态弹性力、资源和环境承载力和人类社会影响力得分分别为0.222、0.062和0.063。（2）2016年,迭部县单位面积水源涵养量为111.76 mm,水源涵养功能处于“高”状态,其中,水源涵养功能较高地区主要集中在以草地和针阔混交林为主的区域。（3）自然栖息地面积占迭部县总面积的83.67%,其自然栖息质量指数(Natural Habitant Quality Index,NHQI)处于“高”状态。（4）从自然和经济2个因素进行分析,发现迭部县生态环境条件较好,但林草地面积已呈现出逐渐减少状态,因此需要通过合理科学的开发引导,发展文化旅游事业,推动迭部县的可持续发展。     

单叶刺槐半同胞子代叶片的滞尘能力及叶表SEM特征分析

以单叶刺槐母本(A1-1)及6个叶形产生明显变异的半同胞子代无性系(A20-5、B24-3、C24-2、B23-1、C24-1、C23-1)新鲜叶片为材料,测定各样本的单位叶面积总颗粒物滞留量、颗粒物粒径分析及叶表微观结构SEM特征,通过相关性分析,筛选与滞尘能力相关的叶形及SEM指标,运用隶属函数法,依据各样本滞尘指标的隶属度均值对滞尘能力进行综合评价。结果表明:子代B23-1对空气中总颗粒物的滞留能力最强,C24-1对PM2.5的滞留能力最强,A20-5对PM2.5-10及PM>10的滞留能力最强;部分叶形及SEM特征指标与滞尘指标之间存在显著相关性;综合评价滞尘能力,全部样本可分为4类,第Ⅰ类为B23-1,滞尘能力强;第Ⅱ类为C24-1,滞尘能力较强;第Ⅲ类包括母本、A20-5、C23-1、C24-2,滞尘能力中等;第Ⅳ类为B24-3,滞尘能力相对较差。