肯尼亚的土壤保持

<正>1 概况肯尼亚是一个东非国家,位于东经31°~41°的赤道地区。国土面积;582 648km~2,现有人口大约为420万。农业是肯尼亚经济的支柱,可耕种面积占国土面积的1/5。因为人口以每年略高于3%的速度高速增长,所以肯尼亚需要在有限的土地资源上扩大农业生产以保证农业对国民经济的有效支持。通过保护水土资源,这一设想可能得以继续。     

北京市森林生态系统土壤保持能力的综合评价

为客观认识北京市森林生态系统的土壤保持功能,选用植被覆盖度、枯枝落叶厚度、林分类型、郁闭度和群落结构等5项指标,综合评价了北京市森林土壤保持能力的相对大小.结果表明:北京市森林生态系统的土壤保持能力较高,其中65.7%的森林保持土壤能力为中等以上,16.8%的森林保持土壤能力较低;不同区县森林的保土能力存在差异,其中石景山区的森林保土能力最高,其次为延庆县、密云县和门头沟区,而大兴区森林的保土能力最低;随着海拔高度增加,森林保持土壤的能力升高,即中山区(海拔＞800 m)森林的保持土壤能力最大,而平原区(海拔＜100 m)森林保持土壤能力较低;地形坡度增大,森林保持土壤能力也增加,不过坡度25°以上森林的保土能力接近;林地土壤类型不同,森林保持土壤能力也不同.其中土壤类型为山地棕壤、山地草甸土和褐土的森林保土能力较高,而为水稻土、潮土、风砂土和草甸沼泽土的森林保土能力较低.     

论森林与土壤保持

本从森林土壤抗蚀性，林木根系对土壤固持作用，森林改良土壤作用，降低径流侵蚀力等方面论述了森林防止土壤侵蚀的良好功能，并从森林覆盖率，林地利用方式等与土壤侵蚀的关系阐明了森林的保土作用，对充分认识森林的水土保持作用，推动森林的保护和绿化事业具有重要意义。     

中国农田生产系统土壤保持功能及其经济价值

农田生产系统不仅为人类提供了多种多样的农产品,同时,农作物对地表的覆盖以及各种水土保持措施的采用,使农田生产系统也发挥着重要的土壤保持功能。根据计算,我国农田生产系统每年保持土壤的数量为101.9×108t,其中,西南地区、黄土高原区和东北地区的农田土壤保持功能最为突出。采用市场价格法、机会成本法和影子工程法对农田保持土壤的价值进行评估,结果表明:我国农田每年保持土壤养分的价值为4408.50×108元/a,减少耕地废弃价值为164.09×108元/a,减轻淤积的价值为53.74×108元/a,总计4626.66×108元/a,相当于2000~2002年我国种植业平均产值的32.08%。其中,东北地区、黄土高原区和西南地区保持土壤价值较大,合计为2851.8×108元,占总价值的61.6%。     

伊洛河流域土壤保持生态服务功能动态变化

[目的]分析河南省伊洛河流域土壤保持生态服务功能的动态变化特征,为流域水土保持和生态管理建设提供参考。[方法]采用修正通用水土流失方程(RUSLE)和统计学方法,分析2010—2020年伊洛河流域土壤保持功能时空变化特征以及影响因素。[结果](1)2010—2020年伊洛河流域土壤保持功能呈递减趋势;空间分布基本一致,整体呈西南高,东北低的分布格局。(2)不同生态系统类型的土壤保持功能差异较大,2010—2020年森林和灌丛生态系统土壤保持总量较高,农田生态系统面积最大,但土壤保持功能较弱。(3)不同海拔和坡度的土壤保持功能随海拔和坡度的增加不断加强。(4)2010—2020年伊洛河流域土壤保持功能空间差异性主要受地形因素的控制,时间变化主要受降雨侵蚀力的影响。[结论]应注重和维护土壤保持功能较强的森林和灌丛生态系统,增强农田生态系统的水土保持措施,从而提高流域土壤保持功能,有助于提升伊洛河流域的生态安全。     

杭州湾南岸农业生态系统土壤保持功能及其生态经济价值评估

文章运用土壤通用流失方程(USLE)研究了杭州湾南岸农业生态系统的土壤保持功能,并评价了其经济价值.研究表明,由林地、水田和旱地组成的杭州湾南岸农业生态系统的土壤保持量为5.67×105 t/a,其经济价值为20.35×105元/a,其中减少土壤废弃的经济价值为12.33×105元/a,保持土壤养分价值为4.92×105元/a,减少泥沙淤积价值为3.10×105元/a.     

退耕还林还草工程的土壤保持效益及其生态经济价值评估--以固原市原州区为例

退耕还林还草工程的土壤保持效益可以看作是由农田生态系统转变为林草生态系统土壤保持服务功能的增加量。参考国内外关于生态系统服务功能中土壤保持功能的评价方法,采用市场价值法、机会成本法、影子工程法、恢复费用法对固原市原州区退耕还林还草工程土壤保持经济价值进行了估算。退耕还林还草工程的年土壤保持总价值为8634．39万元,其中减少养分损失价值为8148．62万元,减少土地废弃价值为19．43万元,减轻泥沙淤积灾害价值为466．35万元。     

中国森林生态系统保护土壤的价值评价

 针对我国森林保护土壤的生态价值,用机会成本法、影子价格法和替代工程法,对我国森林生态系统在减少土地废弃、土壤养分流失及泥沙淤积等方面的价值进行了估算。结果表明:我国森林每年减少土地废弃的总经济价值为6亿2414万元;每年减少的土壤N、P、K损失的经济价值为4538亿7240万元;每年减少淤积泥沙的经济价值为13亿7545万元。以森林为主的森林生态系统每年减少土壤侵蚀的总经济价值为4558亿7200万元。我国主要森林生态系统保护土壤服务功能价值大小顺序为:亚热带>热带>温带草原>寒温带>温带>温带荒漠>暖温带>青藏高原。我国亚热带土壤保持量最大,为32亿8704万t/a;温带荒漠最小,为2亿6214万5000t/a。     

赣南地区土壤保持功能的时空变化特征

[目的]分析赣南地区土壤保持功能时空特征,为提升该区土壤保持能力和维护南方丘陵生态安全屏障提供科学依据。[方法]利用InVEST模型,计算2000,2010,2018年赣南地区不同土地利用类型、不同高程、不同坡度、不同县域的土壤保持强度,分析土壤保持强度与NDVI空间相关性和赣南地区土壤保持功能时空特征。[结果](1)2000—2018年,研究区耕地、灌林地、水域和未利用土地面积都处于减少趋势,城镇用地和农村居民地面积都有较大的增长。(2)土壤保持强度由189.93 t/(hm²·a)上升为190.50 t/(hm²·a),其中有林地土壤保持强度最高,并由259.85 t/(hm²·a)上升为262.03 t/(hm²·a)。(3)赣南地区土壤保持强度呈现四周高、中部低的分布格局,随海拔升高先升高再降低,随坡度升高而升高。(4)土壤保持强度与NDVI在双变量局部空间自相关分析中呈现显著正相关(p<0.01),高高集聚区在赣南地区北部、西部及南部;高低集聚区为中部地区(于都县);低低集聚区为高经...     

基于GIS技术的伊金霍洛旗土壤保持生态服务功能价值评价

以生态服务功能理论为背景,在地理信息系统技术的支持下,分别从水蚀和风蚀两部分估算了伊金霍洛旗1990年和2000年的土壤保持价值。结果表明:2000年和1990年相比,总体土壤侵蚀量略有下降,约减少190000t,生态系统保持土壤量上升了200000t,生态系统的保持土壤价值增加了41.567万元。     

山东省水土保持区划探讨

本文对山东省水土保持区划工作进行了探讨。作者根据全省自然条件、社会经济情况, 影响土壤侵蚀的诸因子, 及水土流失现状等综合因素, 提出了山东省水土保持区划原则, 并依据分区原则, 在水利部统一划分一级区、二级区的前提下, 将全省共划分3个三级区、12个三级亚区。     

Using plot soil loss distribution for soil conservation design

Soil conservation design is generally based on the estimation of average annual soil loss but it should be developed taking into account storms of a given return period. However, use of frequency analysis in soil erosion studies is relatively limited. In this paper, an investigation on statistical distribution of soil loss measurements was firstly carried out using a relatively high number of simultaneously operating plots of different lengths, λ (11, 22, 33 and 44 m) at the experimental station of Sparacia (southern Italy). Using a simple normalization technique, the analysis showed that the probability distribution of the normalized soil loss is independent of both the scale length λ and the temporal scale, which are completely represented by the mean soil loss calculated for a given event using all replicated data collected in plots having the same length. Then, a comparison between the frequency distribution of soil loss and rainfall erosivity index of the USLE was carried out. An estimating criterion of the annual soil loss of a given return period was also developed. By this criterion, the frequency distribution of the rainfall erosivity factor can be used to design soil conservation practices.     

近十年土壤侵蚀与水土保持研究进展与展望

在当今生态文明背景下,土壤侵蚀与水土保持研究迎来了新的发展机遇和挑战。本文首先采用文献计量学方法,定量分析了近10年来国内外土壤侵蚀与水土保持学科发展现状。在此基础上,结合社会需求的变化,阐明了学科发展需求与存在问题。最后,提出了本学科研究的重点领域与方向:水文过程与侵蚀产沙机理,土壤侵蚀过程及其定量模拟,全球变化下土壤侵蚀演变及其灾变机理,社会经济系统—水土流失的互馈过程,以生态功能提升为主的土壤侵蚀防治,以及土壤侵蚀研究新技术与新方法等。     

龙须草水土保持效益研究

对龙须草地水土保持效益研究结果表明 ,与空旷地相比种植龙须草可降低土壤容重 0 .13g/cm3 ,增加土壤总孔隙度 4 .9% ,提高土层土壤贮水量 14 .9% ,年土壤侵蚀量 4 72 .7t/km2 ,比对照减少 94 .5 % ,生态效益和经济效益显著。     

Quantitative assessment of effectiveness of soil conservation measures using a combination of Cs radioactive tracer and conventional techniques

Quantitative assessment of soil redistribution in landscapes remains a challenging task. In this study we used radioactive soil redistribution tracer ¹³⁷Cs together with soil morphological characteristics and empirically-based modeling for quantitative assessment of long-term soil conservation effectiveness. Three pairs of arable slopes were selected, all located within the territory of the Novosil experimental station (the Orel Region, central European Russia). One slope in each pair undergone creation of artificial terraces with forest shelter belts located parallel to topography contour lines and spaced at approximately 100 m from each other.Preliminary results have shown that slopes with soil-protective measures are characterized by a 11–80% reduction of average soil redistribution rates, as shown by soil profile morphology and ¹³⁷Cs methods. Discrepancy in values obtained can be attributed to differences in temporal resolution of methods as well as possible influence of individual extreme events on results yielded by the ¹³⁷Cs method. On the other hand, more significant decrease in average soil degradation rates on slopes with soil conservation (62–75% for each pair of slopes) was predicted by the model.The ¹³⁷Cs method overestimates gross and net soil redistribution rates, as a result of the influence of extreme erosion prior to tillage mixing of a fresh fallout isotope, not accounted for by calibration models used. Another shortcoming of the estimations obtained is that sediment redeposition directly within forest belts was not taken into account. Therefore, net erosion rates obtained for slopes with forest belts should be regarded as overestimation. Nevertheless, it can be generally concluded that the multi-technical approach has allowed acquiring much more detailed information on temporal and spatial variability of soil redistribution rates than single method-based studies.     

Application of a low-cost database to soil erosion and soil conservation studies in the Awash Basin,Ethiopia

In large-scale land resource planning exercises, Geographical Information Systems (GIS) form a valuable means of storing, retrieving, displaying, and analysing spatially-referenced data, as well as enabling the simulation of the consequences of various alternative development options. However, at this scale only generalized policies for the allocation of finance can be made, and the implementation of those policies will invariably require detailed evaluation at the local level. This suggests that expenditure on the central planning process itself should be limited, with funds reserved for later site studies. The form of GIS adopted centrally should also lend itself to easy use and interpretation by policymakers and planners. These requirements suggest that GIS development using proprietary off-the-shelf database management software may be preferable to high-technology GIS software. This paper outlines the development of such a GIS, based on dBase-III-plus and its internal programming language, in the analysis of problems of soil erosion and soil conservation in the large (110,000 km²) drainage basin of the Awash River in Ethiopia. The methodology employed involves the FAO modification of the Universal Soil Loss Equation, which clearly lacks a secure process basis, but is appropriate for the scale of planning involved and the quality of calibration data available. The GIS is used to map patterns of soil erosion, to identify target areas for conservation on the basis of criteria of sensitivity to land use change, and to assess the costs and benefits of conservation work in those areas. It is suggested that the simple form of GIS involved in this study has much to offer environmental managers in developing countries in the rapid development of plans for soil conservation.     

A pragmatic approach to modelling soil and water conservation measures with a catchment scale erosion model

To reduce soil erosion, soil and water conservation (SWC) methods are often used. However, no method exists to model beforehand how implementing such measures will affect erosion at catchment scale. A method was developed to simulate the effects of SWC measures with catchment scale erosion models. The method was implemented by applying the LISEM model to an agricultural catchment on the slopes of Mt. Kenya. The method consisted of a field scale calibration based on P-factors, followed by application at catchment scale. This calibration included factors such as saturated conductivity, Manning's n, roughness and slope angle. It was found that using data on P-factors, such models can be calibrated to give acceptable predictions at pixel scale. However, P-factors were also found to vary with land use type and storm size. Besides, more data on the physical effectiveness of SWC measures are needed. At catchment scale, the effect of SWC was found to be different from that at pixel scale. Most SWC were simulated to be more effective at catchment scale, indicating additional infiltration during transport through the catchment to the outlet. However, slope corrections in case of terraces were found to be less effective at this scale. Nevertheless, a simulation for current land use with current SWC measures indicated that these SWC measures decrease runoff by 28% and erosion by 60%.     

水土保持功能评价及其在水土保持区划中的应用

随着国家对生态文明建设的日益重视,以及国家及地方主体功能区规划的实施,对于水土保持的功能研究也越来越多.结合全国水土保持规划工作的需要,提出水土保持功能的概念、类型确定原则和功能类型,阐述了水土保持基础功能和社会经济功能的评价方法,以及各基础功能的评价指标体系.以太行山东部山地丘陵区为例,举例说明水土保持功能评价的过程和结果.对全国水土保持区划三级区基础功能进行统计分析,明确各功能的区域比例,提出8个一级区水土保持工作主要方向,维护和提高区域水土保持功能将成为水土保持工作的重点和方向.     

New sciences & technologies in soil conservation and eco-sustainability

Soil conservation is necessary to achieve a sustainable world because soils play a crucial role in the Earth's system. At the same time, the applicable and precise methods are vital to obtaining credible data in soil studies. A collection of 10 articles have been organized to focus on the new technologies regarding soil conservation and eco-sustainability and the results related to the novel approaches. The articles put effort into the innovative works of field investigations, field experiments, model experiments, and numerical simulations. Pivotal questions baffling soil scientists have been clarified and solved, and many valuable insights have been aroused.