Abstract A natural gas pipeline extends over a distance of 310 km in the Hebei Province of China and passes through various zones of natural vegetation, mostly wooded. Construction required a working width of about 40 m and a 1.4‐m‐wide trench to be dug to a depth of 2.4 m to enable the installation of a pipe with a diameter of 1,016 mm. The construction process had to manage an irregular configuration of terrain with steep slopes, varying degrees of instability, and a propensity for erosion and land degradation. To prevent potentially massive soil erosion and further deterioration of the affected environment, a comprehensive soil and water conservation plan was designed and implemented. A 3.25‐km‐long study area was selected in rugged hilly country and was divided into seven topographic zones, with slopes ranging from <10° to over 50°. Different soil and water conservation measures were adopted in each zone, including engineering measures, revegetation measures, and maintenance measures. One year after installation, trees planted in individual holes grew well in each zone and the vegetation cover on the slopes treated by hydroseeding exceeded 90%. In addition, run‐off and sediment yield on slopes were significantly reduced. These conservation measures were conducive to environmentally sustainable development and may serve as a scientific reference for ecological restoration and vegetation reconstruction in future pipeline construction projects in similar terrain. Furthermore, these measures also helped to ensure the safe operation of the pipeline and provided protection for people living and working along the pipeline route.
Abstract Biological soil crusts (BSCs), which cover 35% of the continents and exceed 70% of the living cover in parts of region, play important ecological roles in the evolution of soil–water–plant systems in arid and semiarid areas. Since the 1980s, studies of BSCs have become hot topics in physical geography. By reviewing the last 30 years of study reports, the present paper proposes the following future research focus: (1) Understanding the function of BSCs in carbon and nitrogen fixation in the micro‐scale (block), monitoring its distribution patterns in the macro‐scale (region) by remote sensing technology and geographic information systems, and evaluate the role of carbon and nitrogen fixation in the whole ecological system. The response of BSCs to global climate change should also be evaluated. (2) Studying techniques for the artificial fast cultivation or restoration of BSCs, and implementing engineering propagation and application of artificial BSCs, and determining the appropriate parameters for environmental criteria, including light, temperature, soil water moisture, and fertilizer, among others. Artificial cultivation and rapid propagation techniques could present significant perspectives for engineering applications.
Based on 20years long-term experiment of applying fertilizers on continuous wheat.This experiment studied the yield effects and soil fertility evolution of long-term location application of fertilizer on wheat in dry land of loess plateau.The results showed that fertilizer single applying or combine applying had effects on wheat yield,In abundant precipitation years the effects order was NPMNMNPPMMNPCK.The combine fertilizer application could improve yield stably;and there was significantly relation between NP,NM,PM and NPM,these results were all positive;The combine fertilizer application increased the contribution ratio of fertilizer to yield and water use efficiency significantly,which was better than single applying.The combination of N,P and manure was best,which increased WUE by 103.5%,and Its contribution ratio of fertilizer to yield was 64.9%.Available potassium was decreased when combine applying N and P,the combination of N,P and manure could improved soil nutrient content.
Based on vegetation communities inside and outside fish-scale pits on the different slopes of small watershed,the relationships between vegetation communities inside and outside fish-scale pits and latitude as well as slope aspect are discussed.The results drawn from this case study are as follows:(1) The coverage of the vegetation community inside fish-scale pits on northern slope is higher than that on southern slope, reaching a very significant level.(2) Slope aspect is not the dominant factor in determining the diversity of the vegetation communities.(3) The relationships between altitude and the vegetation community richness outside fish-scale pits with different land uses,Shannon—Wiener indexes,and indexes for the vegetation communities inside and outside fish-scale pits with the same land use pattern can be described by parabolic functions,reaching a remarkably significant level.However,the relationship between altitude and diversity indexes of vegetation communities inside fish-scale pits does not reach a significant level.The results imply that community diversity can be increased by methods of changing niche,such as fish-scale pit preparation.
Overburdened stockpiles, a kind of typical loose mixture composed of different proportions of soil and gravel that are created by various production and construction projects, are one of the main sources of man-made accelerated erosion. Because of their specific source of production and unique three-dimensional shape, overburdened stockpiles often present a peculiar erosion process given rainfall conditions. To study this erosion process, a stockpile platform device was designed and used to simulate three-dimensional overburdened stockpiles. A series of indoor artificially simulated rainfall experiments at different precipitation intensities were conducted using loessial soil with different gravel contents. The following key results were obtained: (a) the runoff rate and flow velocity had the same trend over time – that is, a rapid increase, followed by a slower increase and stabilization, while the three-dimensional shape resulted in smaller numerical values of the Reynolds number and Froude number than a rectangular slope; (b) the sediment yield increased exponentially in response to the increasing rainfall intensity and decreased with increasing gravel content in a logarithmic manner; and (c) stream power could be the optimal factor describing soil erosion because it produced the strongest correlation and fitting degree for soil detachment rate. These findings improve our understanding of the hydraulic characteristics and erosion processes of overburdened stockpiles and also have implications for predictive soil and water loss models.
With the rapid development of dense apple tree plantings with the dwarf rootstock cultivation method, determining accumulation and distribution characteristics of soil mineral nitrogen in densely planted orchards with dwarf rootstock is important to enable scientific fertilization of apple orchards. We investigated densely planted apple orchards with dwarf rootstocks and different plant ages (6 a, 9 a, and 12 a). We collected soil samples under trees, between trees, between rows, and at the midpoints between the trees and rows, and examined the accumulation and distribution characteristics of nitrate, ammonium, and mineral nitrogen. The cumulative amount of nitrate in the 0-300 cm soil layer increased with plant age. The difference between orchards with different plant ages was significant and showed the trend 6 a<9 a<12 a. The cumulative amount of nitrate increased from 1729 kg·hm-2 to 3771 kg·hm-2 with increasing plant age. The ammonium content was low for orchards of all plant ages and had little effect on the accumulation and spatial distribution of mineral nitrogen. There were two accumulation peaks of nitrate nitrogen in the vertical direction. The depth of soil layer where the second accumulation peak was located decreased from 180 cm to 220 cm with increasing plant age. In the horizontal direction, soil nitrate nitrogen content between rows increased from 27 mg·kg-1 to 138 mg·kg-1 with increasing plant age, representing a more than 400% increase. The difference between orchards with different plant ages was significant. In summary, excessive usage of nitrogen fertilizer and serious leaching of nitrate were problematic in all orchards with different ages. Less nitrogen fertilizer should be applied, and anti-seepage measures should be used at the fertilization location to prevent the leaching of nitrate to deep layers.随着苹果矮砧密植栽培模式的迅速发展,揭示矮砧密植苹果园土壤矿质氮的积累与分布特征对果园科学施肥具有重要意义。本研究以不同树龄(6 a、9 a、12 a)的矮砧密植苹果园为对象,在树下、株间、行间以及树干与行间的中间点位置采集土样,分析土壤硝态氮、铵态氮和矿质氮的积累与分布特征。结果表明:0～300 cm土层土壤硝态氮累积量随果园树龄的增大而增加,不同树龄的果园之间差异显著,表现为6 a＜9 a＜12 a,硝态氮累积量由1729 kg·hm-2增长到3771 kg·hm-2;而各树龄果园的铵态氮含量较低,对矿质氮的积累与空间分布特征基本不构成影响。在垂直方向上,硝态氮存在两个累积峰,第2个累积峰所在的土层深度随果园树龄的增大由180 cm下移到220 cm;在水平方向上,行间位置的硝态氮含量随果园树龄的增大由27 mg·kg-1增长到138 mg·kg-1,涨幅超过400%,各树龄果园之间差异显著。综上,各树龄果园均存在氮肥施用过量和硝态氮淋溶严重的问题,生产中应减少果园的氮肥施用量,同时应在施肥位置布设防渗措施阻止硝态氮向土壤深层淋溶。.
The original intention of implementing traditional soil and water conservation measures was to protect land resources of the water source region.But,it affected water supply of the water receiving area,due to neglecting influence to water resources of downstream and the increase of runoff reduction of the watershed along with the deepgoing treatment.In order to guarantee water supply of the water receiving area,improving traditional patterns and taking new soil and water conservation measures had become practical selections for increasing water delivery of the water receiving area and improving ecology of the water source region.It concludes that these measures are inappropriate for soil and water conservation in the water source region based on the analysis of limitations of various traditional soil and water conservation patterns.It also discusses the main principles and concrete configuration measures of new soil and water conservation measures.
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