半干旱区两种草原类型植物体内草酸钙研究

本文利用连续组分法测定了半干旱区两种草原类型植物体内的草酸钙含量,在宁夏盐池北部的宁夏哈巴湖国家级自然保护区（植被为荒漠化草原）采集了91种植物,在内蒙古正蓝旗中北部（植被为典型草原）采集了77种植物。结果表明,在宁夏哈巴湖,草酸钙含量最高的物种是猪毛菜（Salsola collina）、沙蓬（Agriophyllum squarrosum）、尖头叶藜（Chenopodium acuminatum）、草原石头花（Gypsophila davurica）和虫实（Corispermum declinatum）,内蒙古正蓝旗植物草酸钙含量最高的物种是灰绿藜（Chenopodium glaucum）、猪毛菜（Salsola collina）、碱地肤（Kochia scoparia var.sieversiana）;两地禾本科草本草酸钙含量均显著低于非禾本科草本,宁夏哈巴湖自然保护区和内蒙古正蓝旗禾本科草本的草酸钙含量比非禾本科草本分别低56.37%和45.29%;C₃植物体内的草酸钙含量显著低于C₄植物。可见,植物体内草酸钙是植物长期适应进化的结果。     

Uncertainties in up-scaling N2O flux from field to 1°×1° scale: A case study for Inner Mongolian grasslands in China

Since N₂O emissions cannot be measured easily at large scales, global emission estimates inevitably involve problems with scaling. To date, up-scaling processes depend highly on the models and database. Because of the limitation in resolution of the databases, which provide input parameters to drive the model's regional simulations, the uncertainties generated from the up-scaling processes must be quantified. In this paper, the uncertainties in up-scaling N₂O emissions from the field scale (∼1 km²) to 1°×1° scale (∼10,000 km²) were quantified in a case study from the Xilin River basin of Inner Mongolia, China. A revised process-based DNDC model was applied in the study for quantifying N₂O fluxes with a high-resolution (1 km²) soil database constructed with remote sensing data and GIS technique. The results showed that the uncertainties coming from spatial scaling effect is 63.6%, and from the partitioning of sensitive model parameter (SOC) is 86.4%. We found that inclusion of spatial heterogeneity of soil factors resulted in lower regional N₂O emission estimates. Utilization of the spatial structural information based on soil type was more effective for reducing the spatial scaling effect in comparison with the variability information calculated from Monte Carlo method.     

C-NMR analysis of decomposing litter and fine roots in the semi-arid Mulga Lands of southern Queensland

Plant litter and fine roots are important carbon (C) inputs to soil and a direct source of CO₂ to the atmosphere. Solid-state carbon-13 nuclear magnetic resonance (¹³C-NMR) spectroscopy was used to investigate the nature of C changes during decomposition of plant litter and fine roots of mulga (Acacia aneura F. Muell. Ex. Benth.), wheat (Triticum aestivum L.), lucerne (Medicago sativa) and buffel grass (Cenchrus ciliaris) over an 18-month period. Alkyl C was closely associated with total N concentrations in all litter materials during decay and as alkyl C increased so did total N, indicating an increase in refractory biomacromolecules. Mulga phyllodes had the greatest alkyl C concentration of all litter and fine root materials, and also exhibited the NMR peaks assigned to tannins that may slow or hinder decomposition rates and nitrification. Mulga litter and fine roots decomposed slower than all other litter materials and the soil under mulga had the highest soil C concentration, indicating slower CO₂ release. The alkyl C-to-O-alkyl C ratio is generally used as an index of the extent of decomposition, but is not useful for the decay of woody components. Of all the NMR ratios studied that may indicate the extent of decomposition, the carbohydrate C-to-methoxyl C ratio proved to have the strongest and most consistent relationship with decay time, fraction of mass remaining and total C, even though increases in alkyl C were observed with decreases in carbohydrate C.     

Medium-term gully headcut retreat rates in Southeast Spain determined from aerial photographs and ground measurements

This paper deals with gully retreat rates at different time scales, whereby the short-term time scale may span a time interval of 1–5 years, the medium-term time scale a time interval of 5–50 years, and the long-term time scale a time interval of more than 50 years. An analysis of high-altitude aerial photographs in combination with ground measurements allowed us to quantify volumetric gully-head retreat rates for 12 permanent gullies in Southeast Spain (Guadalentin and Guadix study areas) over a 40–43 year time interval (medium-term time scale). This resulted in an average retreat rate (V_e) of 17.4 m³ year⁻¹. A power relationship between drainage-basin area (A) and medium-term volumetric gully-head retreat rate, V_e=0.069A^0.380 (R²=0.51, n=21), was found by combining the gully-head retreat rates obtained in this study with those obtained by a dendrochronological method. The exponent (b) and the coefficient of determination (R²) of the power relationships V_e=aA^b increases from the short-term to the long-term time scale, expressing the increasing importance of drainage-basin area in gully development with time. Considerable differences between gully-head retreat rates measured at the short and medium-term time scales at individual gullies showed the importance of land-use changes and unsuccessful management practices on gully-head retreat, and the episodic nature of gully-head retreat when piping and tension cracking are involved. Higher gully-head retreat rates are obtained at the medium-term time scale compared to the short-term time scale but the differences are not significantly different at α=10%. The medium-term methods tend to measure proportionally more high gully retreat rates, but less extreme values compared to the short-term method. This is explained by a more equal distribution of extreme rainfall events both in space and time at a longer-term time scale, and hence a higher probability of measuring the average effect of both small and extreme rainfall events at each gully.     

施肥对半干旱地区小麦产量、NO3——N累积和水分平衡的影响

 依据长武站长期田间试验（1984～2001年）的结果，分析了不同施肥措施条件下小麦产量、氮肥利用率、土壤水分的变化及其相互间的关系。结果表明，对照、有机肥（M）、氮肥（N）、氮磷肥（NP）、氮肥＋有机肥（NM）和氮磷肥＋有机肥（NPM）处理冬小麦的17年平均产量依次为1.5、2.6、2.0、3.3、3.4和4.0 t·ha-1；冬小麦地上部17年累计吸收的氮量依次为509.0、854.6、781.9、1 199.8、1 067.5和1 430.9 kg·ha-1；2001年0～300 cm土层NO3--N储量依次为52.2、113.1、1 064.8、254.5、535.4和512.1 kg·ha-1，N处理的NO3--N分布于0～300 cm土层，NP、NM、NPM处理的NO3--N主要分布于0～180 cm土层。收获期0～300 cm土层多年平均水分含量为CK＞N＞M＞NP＞NPM。播种期NP、NPM处理200～300 cm土层水分出现亏缺。施肥是黄土旱塬区土壤生产力提高、土壤深层水分亏缺和土壤NO3--N累积的驱动力。     

水、氮磷肥及其互作对小麦淀粉糊化特性的影响

为了解豫西半干旱区不同水、肥条件对小麦淀粉品质的调控效应,于2009—2010年度和2010—2011年度在河南省洛阳市农业科学研究院以"洛旱2号"小麦为材料,采用防雨棚池栽种植方式,研究了不同灌水量、施氮量和施磷量及其互作对小麦淀粉糊化特性的影响。结果表明:施氮量和施磷量对小麦淀粉糊化特性均有显著影响(P≤0.05或P≤0.01);随施氮量的增加,淀粉各黏度参数呈增大趋势,施氮量为105 kg.hm 2时达最大值,之后增加施氮量各黏度参数又有所下降;黏度参数在施磷量为168 kg.hm 2时达最大值。在豫西半干旱生态条件下,灌水量对淀粉黏度参数影响不显著,但存在灌水量×施氮量的显著互作效应(P≤0.05或P≤0.01)。从不同水肥处理组合看,淀粉糊化特性以处理组合N105P168W217.5[施氮量105 kg(N).hm 2、施磷量168kg(P2O5).hm 2和全生育期灌水量217.5 mm]最优。相关分析表明,淀粉黏度参数与籽粒产量在2009—2010年度呈显著正相关,而在2010—2011年度相关不显著,说明产量与淀粉品质间存在着协同提高的可能性。     

半干旱区生态恢复关键生态系统识别——以内蒙古自治区和林县为例

我国土地退化严重,且大部分发生在干旱半干旱地区.恢复为何种生态系统类型是生态学研究的重要课题.采用生态功能区划,根据各个生态功能区主体生态系统功能,推导发挥此功能的生态系统类型的方法,识别关键生态系统类型.以内蒙古自治区和林县为例,采用文献调研、实地调查、3S技术等方法,在评价该县生态敏感性、生态服务功能重要性的基础上,将该县划分为3个一级生态区,11个二级生态功能区.根据各个生态功能区的主体生态系统服务功能,分析发挥该功能的可能生态系统类型.再根据全国自然植被区划、气候变化趋势模型以及现状植被类型,识别各个生态功能区的关键生态系统类型.     

油松和侧柏无纺布容器苗雨季移植试验

[目的]研究埋土前取下无纺布容器袋对油松和侧柏苗木生长的影响。[方法]以苗龄为2.5年的油松、侧柏无纺布容器苗为试验材料,雨季移植时分为埋土前取下无纺布容器袋(去袋苗)和保留无纺布容器袋(带袋苗)2个处理,移植1年后,调查移植苗成活率,成活苗木株高、地径、高生长量。[结果]经χ2检验,去袋苗与带袋苗成活率差异不显著;经方差显著性F检验,去袋苗和带袋苗2个正态总体株高方差差异显著,地径方差差异极显著,高生长方差差异不显著;经t检验,去袋苗和带袋苗株高、地径、高生长量平均值差异不显著。[结论]在雨季移植埋土前取下无纺布容器袋对半干旱地区油松、侧柏苗木成活和前期生长无不良影响。     

Simulations of multipurpose water availability in a semi-arid catchment under different management strategies

In the semi-arid Brazilian Northeast, the exploitation of alluvial aquifers for irrigation and domestic supply to rural communities over the last 10 years has upset the traditional mechanisms of water resources management. In the Forquilha watershed (221 km²; 5°17″S, 39°30″W), the two main water resources are reservoirs (with a capacity exceeding 0.9-6.7 × 10⁶ m³), used for domestic water supply only, and an alluvial aquifer (2.3 × 10⁶ m³), used for irrigation and domestic water supply. From 1998 to 2006, the irrigated area with alluvial groundwater increased from 0 to 75 ha, and the fraction of population supplied through domestic water networks, using reservoirs and the aquifer, increased from 1% to 70%. Based on physical and socioeconomic issues, three main water territories have been defined (“Aquifer”, “Reservoirs”, and “Disperse Habitat”). Considering the next 30 years with a realistic population growth, three hypotheses regarding irrigated area (i.e., 0, 75, or 150 ha), and several possible water-management scenarios, hydrological balance models were built and used to simulate the different impacts on water resource availability and salinity. Simulation results showed that, in all cases, releases from the upstream main reservoir are necessary to keep reservoir salinity below 0.7 g L⁻¹ and for guaranteeing domestic needs in the whole watershed. As a consequence, a management approach that takes into account the interrelations among the three territories is necessary. Moreover, the simulations showed that the area of irrigated fields cannot exceed the current extent (75 ha), or serious restrictions on water availability and salinity will take place. Moreover, important socioeconomic problems are expected, including a high cost of palliative water supply with tank trucks from external sources.     

Review of runoff forestry in Shanxi Province and sustainable development tactics of forestry

IntroductionInaridandsemi-aridareas,shortageofwaterresourceswasamajorf8ctorlimitingsustainabledevelopmentofagricuIture,forestryandanimalhus-bandryItreIateddirectlywithlocaltheecoIogicaIforestryandthesocial/economicdeveIopment.lnShanxiProvince,themountainousareasholdsabundantland,Iightandheatresources.buttheseoriginalresourcessuperioritycannotbeusedeff6ctivelybyplantcommunitybecauseofaIong-termsuff6ringfromairorsoildroughtandwatershortage.Especially,becauseofthedestroyactivi-tiesonforestryi…