黄土沟壑区小流域不同地形下土壤微量元素分布特征

研究了黄土沟壑区小流域塬面、坡地、梯田和沟道土壤微量元素的剖面分布特征,以揭示不同地形条件下微量元素的有效性及地球化学特性.结果表明,不同土层土壤全量微量元素的变异系数均小于15%,为小变异土壤性质,有效态和吸附态铁和锰的变异系数均高于36%,为高度变异土壤性质;有效态和吸附态锌和铜属于中到高度变异.全量铁、锰和铜以沟道土壤较高,全锌、有效态和吸附态微量元素含量以塬面土壤较高.不同形态微量元素的剖面分布趋势取决于地形条件.不同地形下成土过程及不同地形条件所对应的土地利用方式造成了全量微量元素的差异,而土壤有机质含量的差异是不同地形条件下有效态和吸附态微量元素剖面分布特征不同的主要原因.     

云南省水土流失DPSIR模型指标体系的构建

根据云南省的立地条件及可获取性原则建立了云南省水土流失评价模型DPSIR的指标体系（16个指标）,并初步分析了各指标的时间变化特征,为进一步定量评估云南省水土流失奠定了基础。     

黄土高原清水河流域土地利用/覆盖和降雨变化对侵蚀产沙的影响

近50 a来,在气候变化和生态恢复与治理工程实施的背景下,黄土高原的侵蚀产沙特征发生了明显的变化。以黄土高原典型中尺度流域清水河流域(面积436 km2)为研究对象,利用1959、1986、2007年的土地利用解译结果和1960—2005年该流域实测输沙和降水资料,采用非参数Mann-Kendall趋势分析法和滑动t检验法研究了该流域年输沙量、降雨量的变化趋势和突变点,并与通用土壤流失方程相结合分析了该流域土地利用和降雨变化对输沙量变化的贡献率。结果表明:该流域年输沙量47 a间有显著的下降趋势,突变点位于1980年;降雨量没有明显的趋势性变化,极端降雨指数下降。降雨因素对输沙量减少的贡献率为9.89%,土地利用的贡献率为90.11%,土地利用变化中工程措施淤地坝的贡献率为5.56%,植被变化的贡献率为84.55%。该流域47 a间乔木林地面积增加了944.27%,灌木林地增加了19.33%,表明清水河流域林地面积增加是导致输沙量减少的主要原因。     

Spatial and long-term variability of soil loss due to crop harvesting and the importance relative to water erosion: A case study from Belgium

The harvest of crops such as sugar beet (Beta vulgaris L.), potato (Solanum tuberosum L.), leek (Allium porrum L.) and carrot (Daucus carota L.) causes soil loss from arable land because soil adhering to the crop and soil clods that failed to be separated by the harvesting machine, are exported from the field together with these harvested crops. These soil losses can be of the same order of magnitude as soil losses caused by water erosion processes, but are often neglected in soil erosion research. In this article we developed a methodology to investigate the spatial and long-term (1846–2004) variability of soil loss due to crop harvesting (SLCH) in Belgium and the spatial distribution of the importance of SLCH relative to soil losses caused by water erosion processes in Flanders. The study is based on long-term time series of soil tare data of crop processing factories and area and crop yield statistics. Until the middle of the 20th century, potato and roots and tubers grown as second crop, had the largest share in the SLCH-crop growing area in Belgium. Sugar beet gained importance from the end of the 19th century onwards and has now, of all SLCH crops, the largest growing area. We could estimate that, partly due to increasing crop yields and the mechanisation of the harvesting process, SLCH per hectare of cropland increased from 0.4 Mg ha⁻¹ year⁻¹ in 1846 to 2.4 Mg ha⁻¹ year⁻¹ in the 1970s and early 1980s. Since then mean annual soil losses decreased again to 1.8 Mg ha⁻¹ year⁻¹ in 2004. It was assessed that total yearly SLCH in Belgium rose from more than 575,000 Mg in the middle of the 19th century to more than 1.7 × 10⁶ Mg in the 1970s and early 1980s, while current SLCH values are 1.4 × 10⁶ Mg. We estimated that since 1846, more than 163 × 10⁶ Mg soil was exported from cropland in Belgium through this erosion process, which corresponds to 109 hm³ or an average soil profile truncation of 1.15 cm. Average sediment export from cropland in Flanders was 3.7 Mg ha⁻¹ year⁻¹ in 2002, of which 46% was due to SLCH and 54% was due to water erosion processes. The relative importance of SLCH varied, depending on the agricultural region, between 38% and 94%.     

Environmental cross-compliance mitigates nitrogen and phosphorus pollution from Swiss agriculture

In 1993 the Swiss agricultural policy was revised with – amongst other goals – the objective of improving the environmental performance of agriculture. A voluntary agri-environmental scheme to promote integrated production (IP) was introduced. In 1999 the IP standards were integrated in cross compliance requirements and termed Proof of Ecological Performance (PEP). We evaluated the effectiveness of this policy in terms of reducing diffuse nitrogen (N) and phosphorus (P) pollution of ground and surface water. We combined monitoring schemes covering the reference period from before the introduction of IP/PEP (1990–1992) with the evaluation of cause/effect relationships in selected case-study areas. The evaluation showed an overall reduction of diffuse N and P pollution from agriculture even though some goals were not reached. Nitrate leaching declined, but only a 3–4 mg L⁻¹ reduction was observed rather than the intended decrease of 5 mg L⁻¹. The P pollution of surface waters from agriculture decreased by only 10–30% instead of 50%. The intended reduction of the nitrogen surplus of Swiss agriculture by 33% was not attained, but the P surplus of Swiss agriculture was more than halved. IP/PEP practices that improved N and P management included reduced N and P fertiliser inputs and pig and poultry feedstuffs with reduced N and P contents, both of which are a consequence of the requirement of equilibrated farm nutrient balances, as well as increased use of cover cropping and of conservation tillage systems.     

南方地区公路建设环评中的水土流失评价要点

水土流失是南方多雨地区公路建设项目的主要生态问题,全面考虑水土流失点、正确预测水土流失量、切实可行地提出减少或消除不利影响的水土防护措施,是公路建设生态环境影响评价的重点。基于南方地区公路建设过程中水土流失的特点,对南方地区公路建设环评中的水土流失评价要点进行了分析探讨。分析结果表明,对南方地区公路建设项目的水土流失影响进行评价时,应选择最佳预测时段并划分不同的预测区,优先选用适宜于当地实际情况的预测模型,从而确保预测结果的可靠性。应从水土流失防护角度筛选最佳的公路设计方案,将水土保持体现在各项具体的工程措施中,以最大限度地减轻公路建设带来的水土流失影响。     

巴东县黄家大沟滨江游憩带工程的主要工程地质问题及防治建议

三峡库区巴东县地表崎岖、崇山峻岭,沿江冲沟发育,但受建设用地的制约,基础设施和配套设施不完善,制约了旅游业的发展.黄家大沟滨江游憩带工程是巴东县城旅游发展规划的一部分,本文研究了该工程存在的主要工程地质问题,并提出了具体的防治对策,以为巴东县及其他沿江地区类似冲沟的碎石土填方工程提供实际参考.     

Describing Damage to Stream Modification Projects in Constrained Settings

Complex relationships between stream functions and processes make evaluation of stream modification projects difficult. Informed by vague objectives and minimal monitoring data, post‐construction project evaluations can often be a subjective attribution of success or failure. This article provides a simple framework to rapidly describe the degree of damage in stream modification projects performed in constrained settings. Based on widely accepted evaluations of physical habitat quality and stream stability, the damage states framework describes a continuum of damage in multiple categories that relate natural stream functions to the often desired state of static equilibrium. Given that channel form is closely related to stream function, it follows that changes to the channel form result in changes in function. The damage states focus on damage to flow hydraulics, sediment transport and channel equilibrium, hydraulic, and geomorphic parameters that describe basic stream functioning and support higher level functions in the modified channel. The damage states can be used in decision making as a systematic method to determine the need for repair and design adjustments.     

有机碳流失对土壤侵蚀的响应及其驱动因素:基于Meta分析

土壤侵蚀是土壤有机碳（SOC）流失的主要驱动力,在全球碳循环中发挥着重要作用.评估侵蚀作用下SOC流失的主要驱动因素及其影响程度有助于深入理解土壤侵蚀作用下SOC的流失机制.因此,通过Meta分析方法,基于2007~2021年间国内外期刊上发表的24个案例,研究了不同气候因素（气候类型、降雨量和降雨强度）和土壤因素（土壤类型、容重和团聚体粒径）条件下土壤侵蚀对中国SOC流失的影响.结果表明：①与无侵蚀扰动相比,侵蚀作用下SOC含量显著下降（整体下降16.0%）,表现出明显的负响应特征;②侵蚀背景下SOC对不同因子的负响应程度为：降雨强度（65.0%）>降雨量（24.3%）>土壤类型（21.4%）>容重（20.2%）>团聚体粒径（16.5%）>气候类型（9.1%）;③主成分分析显示,侵蚀背景下气候因素相对于土壤因素是影响SOC流失的主导因素,降雨强度则再次显示为关键影响因子.深入分析我国土壤侵蚀作用下SOC流失特征及其影响因素,为系统理解土壤侵蚀在碳循环中的作用提供了理论参考.     

A comparative assessment of land management approaches in Bhutan

Arable land in Bhutan is under serious threats of land degradation. Proper land management approach is needed to control soil erosion problems. This study is an attempt to characterize and document the conventional and the community-based land management approaches, applied in Chukha and Dagana districts, respectively. The study tried to make a comparative assessment of their social, economic and environmental impacts on the participating farmers. Farmers’ level of participation in the program, implementation of the soil erosion control measures (SECM) and subsequent social, economic and environmental impacts were found to be significantly influenced by the type of approach applied. The study found that community-based approach is by any means better suited for the study sites than the conventional approach. The social, economic and environmental attributes of respondents from the community-based approach were found to have improved significantly as compared to the conventional approach. The community-based approach was thus found to have a higher potential to meet the diverse requirements of rural subsistence farming communities in Bhutan than the conventional approach.