Soil organic carbon (SOC) is integral to the global carbon cycle. However, the distribution and governing factors of SOC in karst regions remain poorly understood due to frequent land use changes and regional microclimate heterogeneity. This study was conducted at long-term pilot monitoring stations that had been in place for 13–17 years. A survey transect was established extending from the southwest to the northeast of Guizhou Province, China, to statistically assess variations in soil organic carbon storage (SOCs) across five land use categories ( i.e., sloping farmland, bare land, grassland, orchard, and arbor woodland). We found that the SOCs was substantially greater in orchards and arbor woodlands than in grasslands and sloping farmlands. Sloping farmland and grassland SOCs were influenced mainly by annual precipitation (MAP) and altitude (AL), whereas total soil phosphorus (TP) was the main influence on bare land (P < 0.05), orchard (P < 0.05) and arbor woodland (P < 0.01) SOCs. Structural equation modeling revealed that land use (path coefficient: 0.16, P < 0.01) and soil chemical properties (path coefficient: 0.39, P < 0.01) directly governed SOCs, whereas climate (path coefficient: 0.31, P < 0.01) indirectly influenced SOCs by mediating land use. Furthermore, the impact of soil chemical properties on SOCs was limited by land use and soil particle type. Variable decomposition analysis revealed that soil chemical properties independently explained 31.00

Amid global rural decline, the main approach to rural revitalization (RR) is to transform rural ecological resources into development advantages by means of ecological product value realization (EPVR). The fragility of the karst ecological environment limits the development of the karst countryside, and agroforestry is an important way to achieve the ecological protection and economic development of the karst countryside. At present, research on EPVR and RR is rapidly developing. Although there is an increasing number of publications on EPVR and RR separately, the literature on their comprehensive analysis is lacking, and how the karst agroforestry ecosystem can be improved is unclear. The objective of this is to provide an overview of the current research status and challenges of EPVR and RR in order to optimize agroforestry ecosystems in karst desertification control (KDC). This paper systematically analyzed 263 relevant articles on EPVR and RR, and the results are as follows: (1) The number of studies increased exponentially after 2017. The research has primarily focused on the relationship between EPVR and RR, as well as the EPVR and the formation mechanisms of the eco-industry and value accounting of eco-products, which account for 95.53% of the total literature. China has published the most research in this area. At the intercontinental scale, this research is mainly concentrated in East Asia, Europe, and North America. (2) The main progress and landmark achievements in the research on EPVR and RR are summarized. Four key scientific questions that need to be addressed in the future are presented. (3) The above information highlights the three key areas for improving the agroforestry ecosystem in karst desertification control (KDC): the value accounting of eco-products, EPVR, and RR. This study found that EPVR and RR can improve the karst agroforestry ecosystem and further promote rural development, providing significant insights for the overall revitalization of rural areas worldwide and the scientific control of karst desertification.

Quantifying suspended sediment concentration-runoff (SSC-Q) hysteresis can help to understand the source and transport mechanism of sediment. Due to the unique lithology, shallow soil, high infiltration capacity, complex geomorphology and heterogeneous landscape of karst watersheds in southwestern China, SSC-Q hysteresis patterns remain unclear in this region. In the present study, the hysteresis index (HI) was used to quantify the SSC-Q hysteresis pattern. The effects of rainfall and runoff on the HI were also evaluated from 2014 to 2019 in the Mahuangtian (2.26 km(2)) and Muzhaihe (0.09 km(2)) karst watersheds. The results showed that the clockwise loops accounted for more than 60% of the total hysteresis patterns in the two karst watersheds. In contrast, the counter-clockwise and figure-eight loops occupied no more than 30% and 10% of the total hysteresis patterns, respectively. These differences in the hysteresis patterns probably resulted from the spatial distribution of sediment sources and hydrological connectivity. The HI was significantly affected by the maximum discharge in the Mahuangtian watershed (P < 0.05) and by the flashiness index in the Muzhaihe watershed. This may be attributed to their different 3D hydrogeological structure, lithology and watershed size. This study can facilitate a better understanding of suspended sediment dynamics and provide important guidance for accurately implementing soil and water conservation strategies in karst areas.

Southwest China is one of the largest contiguous karst areas in the world. Due to the particularity of geological conditions, extreme rainfall events and unreasonable land use, this region is experiencing severe soil erosion. Therefore, the main purpose of this study is to evaluate the influences of vegetation type and rainfall regime on runoff and soil loss in southwest China. The recording of 143 rainfall events from 2006 to 2015 have been divided into 5 rainfall regimes by K-means clustering method. The vegetation type included soil and water conservation forest, grassland, cropland and economic fruit forest. Results showed that vegetation type and rainfall regime both had significant influences on runoff and soil loss. Among the four vegetation types, the cropland produced the largest runoff and soil loss, and the minimum runoff and soil loss were observed in grassland. The rainfall regime I with the shortest duration and highest rainfall intensity produced the largest runoff, accounting for 45% of the total runoff. The rainfall regime IV with shorter duration and higher rainfall intensity generated the greatest soil loss, occupying about 41% of the total soil loss. The general linear model indicated that the main factors affecting runoff were vegetation type, maximum 30-minute rainfall intensity (I30) and rainfall duration, while the soil loss is highly linked to vegetation type and I30. This study suggested that grassland is a good choice to control soil erosion when land use conversion is implemented. Furthermore, replacing soil and water conservation forest with economic fruit forest can not only effectively control soil erosion, but also increase the income of residents in karst regions. Due to the low soil formation rate in karst areas, the soil erosion risk is still high and great efforts should be paid to control soil erosion and rock desertification in this region.

喀斯特坡地表层岩溶带发育，入渗强烈，产流机制与非喀斯特坡地有较大差异，为提高喀斯特坡地土壤流失模型预测准确性，以贵州省普定县陈旗小流域6个不同土地利用类型径流小区为观测对象，分析2007—2010年、2015—2019年2期泥沙和地表径流数据，了解产流产沙规律，并利用降雨侵蚀力偏差法计算各小区侵蚀性降雨量。结果表明：（1）植被覆盖率与喀斯特坡地地表产流产沙量呈负相关，高植被覆盖下，暴雨和极端暴雨是造成喀斯特坡地水土流失的主要降雨事件；（2）植被恢复十余年随着覆盖度的提高，年均土壤流失量呈显著下降趋势，多小于10 t/km~2;（3）喀斯特坡地裂隙发育，地下漏失严重，土壤量少且不易被侵蚀，除少数极端暴雨外，多数降雨不产流不产沙，因此建议将喀斯特坡地侵蚀性降雨量阈值定为50 mm,该阈值显著高于非喀斯特地区。

Frequent rainstorms caused by climate change are causing significant stresses and impacts on karst zones and even global hydrological systems. However, few reports have focused on rainstorm sediment events (RSE) based on long series, high-frequency signals in karst small watersheds. Present study assessed the process characteristics of RSE and analyzed the response of specific sediment yield (SSY) to environmental variables using random forest and correlation coefficients. Management strategies are then provided based on revised index of sediment connectivity (RIC) visualizations, sediment dynamics and landscape patterns, and modeling solutions for SSY are explored through the innovative use of multiple models. The results showed that the sediment process showed high variability (CV > 0.36), and the same index had obvious watershed differences. Landscape pattern and RIC show highly significant correlation with mean or maximum suspended sediment concentration (p<0.01, |r|>0.235). Early rainfall depth was the dominant factor affecting SSY (Contribution = 48.15 %). The hysteresis loop and RIC infer that the sediment of Mahuangtian and Maolike mainly comes from downstream farmland and riverbeds, while Yangjichong comes from remote hillsides. The watershed landscape is centralized and simplified. In the future, patches of shrubs or herbaceous plants should be added around the cultivated land and at the bottom of the sparse forest to increase the sediment collection capacity. The backpropagation neural network (BPNN) is optimal for modeling SSY, particularly for running the variables preferred by the generalized additive model (GAM). This study provides insight into understanding RSE in karst small watersheds. It will help the region to cope with future extreme climate change and develop sediment management models that are consistent with regional realities.

Few studies have focused on observing long-term localized runoff and sediment yield at a small watershed scale in karst areas in southwest China. In addition, the study of soil erosion mechanisms have also been unsatisfactory. Using hydrological data from 2014 to 2019, this study investigated the rainfall, runoff, and sediment yields in the Mahuangtian small watershed, where covered an area of 2.26 km(2). The results showed mean values of 124 t/(km(2).a) and 13.8 mm for the sediment modulus and runoff depth, respectively. Using the K-medoids clustering method, 112 erosive rainfall events were classified into three types of rainfall patterns based on duration (T-R), rainfall depth (R), and maximum 30-minute rainfall intensity (I-30). Pattern A was characterized by the shortest TR, lowest R, and highest I30; pattern B was characterized by medium T-R, R, and I-30; and pattern C was characterized by the longest T-R, highest R, and lowest I-30. Pattern B caused the largest runoff and sediment yield in the watershed, implying that further attention should be focused on this rainfall pattern to control soil and water loss. In addition, hysteretic loop analyses of suspended sediment concentration and flood discharge suggest that complex and clockwise loops were dominant for all events. This study found that the deposition stored in the subterranean river was the main source of sediment for the watershed. The results of this study provide useful information regarding the relationship between rainfall and runoff sediment in a small karst watershed and advance research on soil erosion mechanisms in karst areas.

以基岩大面积出露地表为特征的石漠化,是西南喀斯特地区最严重的生态环境问题.为揭示坡面基岩出露特点,进而为石漠化相关研究提供依据,选择贵州遵义典型潜在石漠化坡面,系统调查坡面出露基岩的空间分布、走向、出露高度及其影响因素.结果表明:1)与坡面侵蚀程度和土壤厚度相对应,中坡部位基岩出露数量高于上坡和下坡部位;2)调查区基岩平均出露高度为(0.35±0.25)m,且在0～15.坡度范围内,基岩出露高度随坡度增大呈幂函数形式增大;3)基岩走向多与坡向斜交,垂直走向的基岩出露高度(0.43±0.23)m,显著大于斜交和平行走向,在坡面上发挥着重要的蓄水拦沙作用;4)农地上基岩出露高度(0.32±0.26)m,小于林草地(0.37±0.18)m,印证了岩溶地区"原生林草地-农地-石漠-次生林草地"土地演变模式.研究结果可为认识喀斯特地区石漠化坡面基本特征以及坡面土壤侵蚀研究提供数据支撑.

侵蚀性降雨是引起喀斯特黄壤坡面水土流失的主要动力因子.采用贵州省遵义市浒洋水流域2018—2020年4个径流小区92次侵蚀性降雨产流产沙实测数据,研究次降雨条件下,裸露坡面和块石出露小区对产流产沙的影响.结果表明:(1)侵蚀性降雨可以分为A、B、C 3类,A类降雨是造成喀斯特黄壤坡面土壤侵蚀的主要雨型.侵蚀性降雨的标准为次降雨量>6.6 m m或I30>3.6 m m/h.(2)裸露坡面63.27％ 的侵蚀性降雨径流深<0.4 mm,66.30％ 的侵蚀性降雨土壤流失量<1 g/m2,坡面土壤侵蚀量主要是由个别的次降雨所贡献.比较3类降雨,产流产沙的规律总体上表现为A雨型>C雨型>B雨型.(3)土壤流失量主要是由径流深决定,径流深直接决定着坡面产沙的多少.A类降雨中20 mm降雨量是喀斯特黄壤坡面径流深和土壤流失量明显增加的突变值.(4)3类降雨下,块石出露增加了坡面产流量,产流量随着出露率的增加而变大.但产沙量的变化比较复杂,A类降雨下,产沙量随着块石出露率的提高呈明显增加.研究结果对喀斯特坡面水土流失治理和土壤侵蚀预报模型的建立具有重要意义.

分析了喀斯特石漠化地区不同水土保持措施对土壤物理性质和抗剪性的影响,结果表明,不同措施下土壤平均持水性总体表现为水保林>封山育林>经济林>坡耕地>坡改梯,平均土壤容重表现为水保林经济林>封山育林>坡耕地>坡改梯,土壤平均抗剪强度大小排序为封山育林>水保林>坡改梯>坡耕地>经济林,总体表现为水保林增加土壤持水性、土壤孔隙度,降低土壤容重效果显著,封山育林状态下土壤抗剪性最强,坡改梯由于人为扰动增加了土壤容重.综合分析,水保林对土壤物理性质改良效果较好.

Biochar is a carbon-rich solid substance produced by pyrolysis of biomass in anoxic or hypoxic environment, which has been an important application direction in agriculture in recent years. In this study, different concentrations of biochar were applied to the runoff plots of karst yellow soil, and the traditional farming and biochar fertilization methods were used for comparative experiments to analyze the effects of biochar on soil runoff and sediment reduction. The results showed that: 1. For runoff plot that have not taken any measures, the runoff yield and sediment yield were significantly positive correlated, R-2 =0.938, (P<0.01), and for runoff plots that have taken measures, the correlation between runoff yield and sediment yield was low, R-2 =0.048; 2. sediment retaining effects of different runoff plots were: runoff plot of surface covered with biochar > runoff plot of biochar + compound fertilizer> runoff plot of compound fertilizer> runoff plot of biochar> control plot, measures were taken to increase the sediment retaining rate of runoff plots entirely by 44.84% to 99.59% as well; runoff yield effects of different fertilization models were as follows: runoff plot of surface covered with biochar < runoff plot of biochar + compound fertilizer< runoff plot of compound fertilizer< runoff plot of biochar< control plot, and the range of runoff reduction in runoff plots where measures are taken was between 4.40% and 74.74%.

The fragile ecological environment and serious soil erosion in the karst rocky desertification area, which have become important factors restricting the development of agricultural economy. This paper analyzed the rainfall factors and soil loss of different soil and water conservation measures by regularly observing different soil and water conservation measures in the runoff plot of the karst plateau mountain. The results showed that: 1) The use of multiple spatial structures of the land had a significant effect on preventing and controlling soil erosion by comparative analysis of different soil and water conservation measures. 2) Reasonable planting mode had little effect on runoff producing of soil, and its corrosion resistance was ranked only second to soil conservation measures. Therefore, changing the way of human interference with nature and following the laws of nature will help to reduce the damage for the ecological environment. 3) By analyzing the relationship between rainfall, average rainfall intensity, rainfall erosivity and sediment content, rainfall intensity had no significant effect on soil loss, rainfall intensity was one of the factors that produce soil erosion. The relationship between average rainfall intensity and sediment content in water conservation forest was R-2 = 0.95, the linear fitting formula was y = 0.2771x + 3.4629. The average rainfall intensity of corn and broad beans (high-groove planting) and the sediment content were Pearson's significant correlation (R-2 = 0.91), the linear fitting formula was y = 0.7685x - 3.839. The sediment content varies with the average rain intensity, and the correlation was significant. Rainfall intensity was an important factor of soil erosion, while rainfall erosion was one of the key factors in soil sediment production.

为了探究喀斯特黄壤坡面微地形变化特征及其与土壤侵蚀的关系,基于人工模拟降雨试验,结合三维激光扫描技术,分析了坡面地表粗糙度和坑洼体积的变化特征及其与土壤侵蚀的响应关系.小区坡度25°,共有3种雨强(30,60,90 mm/h)和4种块石出露度(0,5.4％,13.1％,42.9％)处理.结果表明:(1)坡面块石出露在小雨强下(30 mm/h)可明显促进产流,产流时间较裸土坡面提前18.0％～57.2％,但大雨强下的影响被弱化.产流产沙随块石出露度的增大呈先增后减,最大值处块石出露度在小雨强和大雨强下分别为5.4％～13.1％和13.1％～42.9％.(2)裸土坡面地表粗糙度和坑洼蓄积量由坡上到坡下呈递增趋势,而块石出露坡面地表粗糙度沿坡面的分布规律不明显,坑洼蓄积量总体上也表现为由坡上到坡下逐渐增大.相同雨强下,块石出露坡面地表粗糙度较雨前的变幅大于裸土坡面,坑洼蓄积量较雨前增大的倍数随块石出露度的增大而减小.(3)当块石出露度小于42.9％时,坑洼体积与产流率、产沙率有良好的线性关系.地表微地形因子可作为侵蚀结果预测的重要参数,也可为特大暴雨事件中漏测数据的补充提供理论基础.

Near-surface features have a great influence on runoff and detachment processes by overland flow, but the contributions are still unclear on steep slopes with yellow soil in subtropical humid regions. Field scouring experiments were conducted to investigate how near-surface features affect hydraulic parameters and detachment rate by overland flow. Five treatments and a baseline (disturbed rootless bare cropland) were designed to identify the contributions from stem-leaves, litter, biological soil crusts (BSCs), root systems and non-disturbance, respectively. The results showed that (1) the values of velocity, Reynolds number and Froude number for vegetated slopes were significantly lower than that of baseline, and stem-leaves made a greater contribution (average of 47.30%) to reducing kinetic energy than the other features; (2) the total contribution rate of grassland was 99.38%, and of this total, 1.19, 1.44, 2.49, 49.79 and 44.47% reductions were attributed to the stem-leaves, litter, BSCs, root systems and non-disturbance, respectively. Root system and non-disturbance dominated the detachment rate reduction; (3) with increasing flow rate or slope gradient, the total contribution rate remained between 98% and 100%; and (4) for each treatment, the relationship between detachment rate and hydraulic parameters remained constant, and the stream power was the best predictor to detachment rate. The study results are helpful in evaluating the effects of near-surface features on erosion control and providing reference for government decision-makers to choose appropriate soil conservation and management practices.

[摘要]水土保持不仅可以改善生态环境,为民众提供优质的生态产品,还可以改善农业生产条件,促进农村产业结构合理调整,提高群众的生活水平,对于夯实贵州省农业基础、保障农业和农村可持续发展、助推脱贫攻坚具有重要意义.贵州省水土保持助推扶贫工作经历了起步阶段和常态化阶段,积累了丰富的经验,即:以加快经济发展为主线,以增加农民收入为核心,以改善农业农村生活条件和产业发展为目标,实现生态效益、经济效益、社会效益相统一,在助推扶贫工作决胜同步小康过程中取得显著成效;结合当地产业发展的实际需要,统筹国家生态利益和群众经济利益的需要,推进水土保持"以奖代补、先建后补"管理体制与机制的创新,突出"系统治理、两手发力",充分吸引社会力量和民间资本参与水土流失治理,加块水土保持和农旅产业发展的深度融合,助力脱贫攻坚,改善生态环境.

喀斯特地区水土流失综合治理是实现保水固土、恢复生态环境和改善人民生活的方法之一,为确保国家农业综合开发项目23个重点县的水土流失治理取得更好的成效,全面总结国家农业综合开发水土流失治理中取得的经验与方法十分重要.本文以贵州省兴义市拢岸小流域为例,结合农业综合开发工作的基本情况,分析总结水土流失综合治理中的经验与模式,对全省及全国农业综合开发水土流失治理具有重要的指导意义.

生产建设项目所造成的水土流失生态破坏是生态环境损害的表现形式.生产建设类项目的生态环境损害主要表现在破坏土壤和土地资源、改变(破坏)水文循环和水资源量、降低林草植被结构和覆盖度、破坏原有生态系统平衡;房地产项目造成的生态环境损害以土壤结构破坏、径流量变化和项目区水土保持生态服务功能下降等生态破坏为主,矿山开采项目要关注尾矿库可能引起的污染风险.生态环境损害价值评估以水土流失生态破坏实物量化为基础,通过对比项目区生态破坏质量现状与基线差距,分类确定不同生产建设项目的生态环境损害范围、程度和数量并比选生态环境恢复方案,以期研究结果为生产建设类项目水土流失生态环境损害鉴定评估提供技术支撑.

贵州省安顺市西秀区地处黔中腹地,素有“黔之腹,滇之喉,粤蜀之唇齿”之称,距省会贵阳90 km,总面积1 710 km2.西秀区属亚热带季风性湿润气候区,海拔1 200～1 600 m,年均气温14℃,冬无严寒,夏无酷暑,气候宜人,空气质量优良率达100％,森林覆盖率43％,被誉为“天然空调和大氧吧”,是国家级主体功能区“黔中经济区”、贵安新区规划建设的核心区、全国休闲农业和乡村旅游示范县、全省文明城市、全省首家国家级绿色能源示范县、全省生态文明先行示范区.

目前,中国西南喀斯特地区流域尺度产流产沙长期定位观测试验报道较少,且其相关机制的探讨不足.该文基于小流域尺度,分析典型喀斯特小流域产流产沙特征,定性、定量探讨喀斯特小流域产流产沙的主要影响因子.选取位于贵州北部的典型喀斯特小流域—遵义浒洋水小流域为研究区,采用小流域控制站定位观测法,在4年连续观测的基础上,分析浒洋水小流域月际、年际产流产沙特征,并重点分析了降雨对小流域产流产沙的影响.结果表明:受喀斯特地区特殊的"二元"侵蚀环境等因素影响,浒洋水小流域产流、产沙高峰不同期,产流高峰出现在10月,多年月均值为63.9万m3,而产沙高峰为6月,116.21t.显著性检验则表明,浒洋水小流域月际产流无显著差异(P>0.05),但6月产沙则显著高于1、2、3及12月(P<0.05),其他月份间产沙无显著差异(P>0.05);受年度降雨的影响,2010-2013年,无论是产流还是产沙,2013年均显著高于其他年份(P<0.05).研究期间,小流域多年平均输沙模数为215.32 t/(km2·a),这一结果与贵州省公布的贵州喀斯特区土壤侵蚀模数279.47 t/(km2·a)接近;该小流域降雨对产流产沙影响显著,降雨强度(I60)同产流产沙在0.05水平上显著相关,而降雨量同产流产沙则在0.01水平上显著相关.结果可为喀斯特地区的水土流失治理提供参考.

To reveal the response of soil erosion on hillslope to land use patterns,terrain and rainfall in Guizhou karst area,Yangjichong small watershed in Longli,Shiqiao small watershed in Bijie were took as the research areas to carry out the experiment of soil erosion.The results showed that among the three land use patterns in Yangjichong small watershed,soil erosion modulus of abandoned land was the lowest,and merely 4.7 t/km2 in 2014,and it was 91.3 t/km2 on the forestland due to the rapid vegetation restoration,it was the highest on the farmland,and reached to 629.5 t/km2.Differentia tests showed that the soil erosion rates on forestland,abandoned land and farmland were significantly different at 0.05 level (p＜0.05).The effect of terrain factor on soil erosion showed that the soil erosion amount increased with the increase of slope length,but the effect of slope length on soil erosion was not significant (p＞0.05).The analysis on correlation between rainfall and soil erosion indicated that soil erosion was positively correlated with rainfall at 0.01 level (p＜0.01),and the quadratic polynomial fitting curve can perfectly describe the relation between soil erosion and rainfall (R2＞0.5).