The Poyang Lake Basin (PLB) has a long-standing history of drought, which has been intensified by global warming, posing significant risks to water security and agriculture. However, the specific patterns of drought, particularly seasonal variations, remain poorly understood, making it crucial to investigate these dynamics for effective water management and resilience planning. We employed calibrated SWAT model to simulate monthly soil moisture in five sub-basins to analyze drought characteristics across the PLB over the past six decades. A Multivariate Standardized Drought Index (MSDI) was then developed with simulated Standardized Soil Moisture Index (SSI) and Standardized Precipitation Index (SPI) based on copula functions. We found that (1) The SWAT can simulate monthly streamflow well with NS being 0.76-0.92 for validation data over the sub-basins in the PLB. (2) The MSDI index indicated that there were more drought events during 1960-1979 and 2000-2019, highlighting a cyclical pattern of drought events in the PLB. (3) The Xiushui River Basin encountered the most extreme drought conditions since 2000, indicating the basin faced a high risk of dry conditions. Additionally, our wavelet period analysis showed an increase in drought frequency after the year 2000, with less distinct periodicity. These findings contribute to our understanding of drought dynamics in the Poyang Lake Basin and offer valuable insights for developing sustainable water resource management and climate adaptation strategies in the region.

Alkaline and organic amendment are effective options to ensure successful phytostabilization in mining-disturbed soil ecosystems. However, the different effects of a blended amendment composed of coal fly ash, compost, and biochar (BCC) on soil microorganisms in mining-disturbed soil ecosystems restored with legumes versus grasses remain unknown. Therefore, we conducted a field experiment to measure the influences of amendment blends on soil physicochemical properties, plant growth parameters, and soil microbial community in mining-disturbed soils after vegetation restoration with legumes versus grasses. We found soil organic matter (SOM), nutrient availability (e.g., available potassium), and soil pH, regulated by the amendment blends, were the dominant edaphic predictors explaining the soil community changes. Specifically, the abundance of gram-negative bacteria and arbuscular mycorrhizal fungi in the field plots restored with legumes increased greater than those in the field plots restored with grasses (P < 0.05). Application of the amendment blends further increased the relative abundances of the total bacteria and total fungi, and decreased the fungal: bacterial ratio in the field plots restored with legumes (P < 0.05), while no significant changes were found for those in the field plots restored with grasses. Moreover, our structural equation model suggests that the shifts in the microbial community after incorporation of the amendment blends were driven by the increased SOM and soil nutrient availability (e.g., potassium), and enhanced soil pH. We thus suggest that legume-based vegetation restoration combined with a blend amendment holding the comprehensive functions of acidic amelioration and nutrient-building would be a preferable option for ecological restoration in the mining-disturbed regions.

Vegetation restoration has long been recognized as a practical way to control soil erosion in the eroded inferior lands of subtropical China. However, limited knowledge is available about the effects of long-term vegetation restoration on soil erosion and erodibility of soils derived from red sandstone, especially in field conditions. In the present study, the impacts of Cynodon dactylon (C. dactylon) and Coreopsis basalis (C. basalis) after 5 years of growth on undisturbed soil slope erosion and the respective contributions of near soil surface components (canopies, roots, and biocrusts) were explored by simulated rainfall experiments. Five years after ecological restoration, treatments greatly increased the organic matter content and average weight diameter of topsoil (0–20 cm) and slightly reduced the bulk density (P < 0.05), increasing aggregate stability. Intact plants (C. dactylon or C. basalis) plus biocrusts reduced the sediment yield rates (SYR) by 98.9% and 98.1%, respectively. The contribution rates of biocrusts for reducing the SYR and apparent interrill erodibility (Ki) were the highest, while the canopies of both plants were significantly more effective in reducing the SYR and Ki than their roots on average (P < 0.05). The contribution rates of biocrusts to the reduction of soil erosion increased as the rainfall intensity increased, while those of canopies showed the opposite trend, regardless of plant species. This study highlights the significant roles of plants with dense canopies and fibrous root system and well-developed moss biocrusts in reducing the water erosion in red sandstone eroded inferior lands. The results may contribute to improving soil and water conservation efforts in red sandstone eroded inferior lands from subtropical regions.

Continual input of neonicotinoid insecticides occurs in the citrus orchards from southern China. However, it is still unknown about the variations in the distribution and accumulation of neonicotinoids in soil profiles along a long-term chronosequence of cultivation and the driving factors contributing to these shifts. Here, changes of neonicotinoids in the 0-100 cm soil profiles with distinct orchard cultivation age (1, 10, and 20 years) were investigated, and their related factors were further determined. The results showed that the total levels of five target neonicotinoids ( n-ary sumation 5NEOs) in the soil profiles were in the range of 0-25.76 ng/g dw. Imidacloprid was the most dominating neonicotinoid, followed by thiamethoxam. We observed higher neonicotinoid accumulations in the soil profiles from the citrus orchards after 10 and 20 years of cultivation. Neonicotinoids migrated deeper into the soil profiles in orchards with a longer time since cultivation. Imidacloprid, thiamethoxam, and the total amount of neonicotinoid ( n-ary sumation 5NEOs) were mainly affected by the cultivation age of citrus orchards (accounting for 58.9% variance; P < 0.001); whereas clothianidin, acetamiprid, and thiacloprid were mainly influenced by soil depths (accounting for 66.9-85.2% variance; P < 0.05). Redundancy analyzes further indicated that the enhanced accumulation of neonicotinoids was mainly correlated with the increase of soil organic carbon (SOC) content and soil porosity, and the reduction of bulk density in the profiles of citrus orchards with increasing cultivation age. This study highlights the finding that we should give more concerns about the contamination and ecological risks of neonicotinoids in the orchards with a long cultivation age.

全球气候变化的背景下,由于降雨不均发生的干旱问题已严重威胁作物生长和粮食安全,探究江西省干旱特征为防灾抗旱和农作物生长提供理论参考.利用江西省15个气象台站1957～2015年的逐日降水资料,以连续无有效降水日数为指标,分别计算了不同季节的干旱频率、干旱站次比和干旱持续天数,得到干旱频率的空间分布特征,并分析干旱站次比和干旱持续天数的年际变化趋势;同时引入逐日干旱频率,研究江西省不同站点的逐日干旱动态变化.结果表明:(1)江西省各地区夏旱和秋旱频发,以7～11月伏秋旱最为严重;(2)春旱主要发生在赣南,夏旱高发地区主要在鄱阳湖平原和赣州南部,全省只有较少地区秋旱轻微,其他大部分地区秋旱较为严重,冬旱呈现由北向南逐渐增大的趋势,一年中赣州都是干旱发生较为严重的区域,为江西省干旱重灾区;(3)江西省与各子区域的变化趋势基本一致.春旱和秋旱年际变化呈增加趋势,仅赣南地区干旱强度略有减小;夏旱呈降低趋势;冬季干旱范围虽有增加趋势,但干旱强度有减轻的趋势;赣南地区干旱情况总体呈减弱的趋势,仅冬季干旱强度有增强的趋势.

为探讨稀土尾矿区人工培育苔藓的可行性及其关键影响因素,选择赣南典型的稀土尾矿,通过室内苔藓培育实验,研究土壤含水量和光照强度对稀土尾矿区苔藓生长发育的影响及其快速培育的可行性.结果表明:1)毛口藓(Trichostomum brachydontium)、卷叶毛口藓(Trichostomum involutum)、扭叶丛本藓(Anoectangium stracheyanum)、纤枝短月藓(Brachymenium exile)等苔藓植物种在稀土尾矿植被恢复过程中具有良好的适应性;2)土壤含水量和光照强度对稀土尾矿苔藓植物的覆盖度、植株密度及生物量的变化有显著影响.土壤水分含量是苔藓植物生长发育的最主要影响因素,接种后保持近地表土壤湿润是人工培育成功的关键;3)在稀土尾矿培育苔藓植物的最佳条件组合是地表土壤水分含量28％～30％+光照强度5 900 lx,苔藓覆盖度在培育50 d后超过60％,在70 d达到100％;低水分(5％～8％)条件下,各光照强度苔藓植物均无法正常生长发育.综上,苔藓植物可作为稀土尾矿矿区生态修复的物种.

Expected increases in extreme rainfall events due to global warming could lead to increased soil erosion in mountainous areas. In order to study this impact on specific areas, the present study identified the spatiotemporal variation of erosive rainfall and the influence of its variation on streamflow and sediment discharge within the Ganjiang River Basin. Daily average rainfall data were obtained from 23 national meteorological observation stations along with streamflow and sediment concentration data collected for 1964-2013 at 6 control stations. The nonparametric Mann-Kendall method and Pettitt test were used for trend analysis and change-point detection, and the modified double mass curve method was used to quantify the effects of both erosive rainfall variation and human activities on hydrological regime shifts. Results showed significant monthly variation in erosive rainfall and significant increases in rainstorms over the entire watershed, particularly in the downstream subzone and northeast corner of the upstream subzone. While moderate rain showed an insignificant decrease in both subzones and the entire watershed, heavy rain showed no significant variation over the entire watershed but did show a significant increase in both the midstream and downstream subzones. The changes in accumulative erosive rainfall had only small effects on reduction in sediment discharge after the change-point year. In contrast, human activities contributed to more than 50% of the changes in sediment discharge in the entire basin. These findings provide a research basis for the study of extreme climate, flood disaster prevention, and soil erosion prediction over the entire watershed.

Sloping farmland is prevalent in hilly red soil areas of South China. Improper tillage patterns induce decreased soil organic matter, soil aggregate breakdown, and nutrient imbalance, thereby restricting crop production. However, the stoichiometric characteristics could reflect the nutrient availability which was mostly studied on bulk soil. The stoichiometric characteristics of soil aggregates with multiple functions in farmlands has rarely been studied. The study was to reveal the impact of tillage patterns on the size distribution, nutrient levels, and stoichiometric ratios of soil aggregates after 20 years’ cultivation. Soil samples of 0–20 cm and 20–40 cm from five tillage patterns, bare-land control (BL), longitudinal-ridge tillage (LR), conventional tillage + straw mulching (CS), cross-ridge tillage (CR), and longitudinal-ridge tillage + hedgerows (LH) were collected. The elemental content (C, N and P) and soil aggregate size distribution were determined, and the stoichiometric ratios were subsequently calculated. Through our analysis and study, it was found that the nutrient content of >2 mm soil aggregates in all plots was the highest. In the hedgerow plots, >2 mm water-stable soil aggregate content was increased. Therefore, LH plots have the highest content of organic matter and nutrients. After 20 years of cultivation, stoichiometric ratio of each plot showed different changes on soil aggregates at different levels. the C:N, C:P, and N:P ratios are lower than the national average of cultivated land. Among of them, the stoichiometric ratio in the LH plot is closer to the mean and showed better water-stable aggregate enhancement. Therefore, longitudinal-ridge tillage + hedgerows can be recommended as a cultivation measure. This study provides a reference for determining appropriate tillage measures, balancing nutrient ratios, and implementing rational fertilization.

The on-going and extensive use of neonicotinoids occur in orchards. However, it is still unknown whether and how orchard management affects soil properties, especially the contents and structure of soil organic matter during orchard development, and their further influences on neonicotinoid persistence. Here, surface soil sam-ples were collected from the citrus orchards with different cultivation ages (1, 10, 14, and 20 years), and their physicochemical properties were determined. Changes in the chemical structure of soil organic matter (SOM) were furtherly examined using solid-state CP/TOSS C-13 NMR. Then, the sorption isotherms of imidacloprid in these soils were investigated. The sorption coefficient (K-d) of imidacloprid at C-e of 0.05 mg/L in the orchard soils increased by 19.4- 23.3%, along a 20-year chronosequence of cultivation, which should be mainly ascribed to the increase of SOM. However, the organic carbon-normalized sorption coefficient (Koc, sorption per unit mass of OM) of imidacloprid declined with increasing cultivation ages. Moreover, the polar and aliphatic domains of SOM had a significantly positive relation to the Koc of imidacloprid, suggesting its key role in governing imi-dacloprid sorption. The results highlighted that reasonable management measures could be adopted to control the occurrence and fate of neonicotinoids in soils, mainly by affecting the content and quality of SOM.

为探明次降雨条件下花生不同生长期红壤坡耕地土壤水分含量变化对水保措施的响应,利用人工模拟降雨试验,研究采取常规耕作、有机肥+常规耕作、稻草覆盖+深翻耕、保水剂+常规耕作等措施的红壤坡耕地小区20 cm深度层土壤水分含量在次降雨过程(1.5h)及降雨结束后1h内的连续变化规律.结果表明:花生不同生长期红壤坡耕地上、下坡20 cm深度土壤含水量在降雨后的变化幅度均呈收获期≈结荚期>盛花期>出苗期>翻耕期(p<0.01).稻草覆盖+深翻耕措施在提高红壤坡耕地土壤蓄水能力方面效果最显著,尤其是在花生翻耕期和收获期,增幅分别比常规耕作措施高26％ 和64％.保水剂对红壤坡地土壤保水效果的促进作用主要体现在花生翻耕期,而花生其他生长期则不明显;而有机肥增施措施对红壤坡地土壤保水效果的促进作用主要体现在花生翻耕期、结荚期和收获期.研究结果表明稻草覆盖+深翻是适合红壤丘陵区坡耕地土壤水分持续高效利用的有效模式.

The priming effect in soils is known to depend in part on the size distribution and decomposability of aggregate associated soil organic carbon. However, the biochar-induced carbon mineralization priming effects within aggregates of different size classes are poorly understood. In this study, the bulk soils were firstly separated into three fractions ( 0.25 mm microaggregate). Then, the bulk soils and different aggregate-size fractions were incubated for 180 days following the incorporation of biochar (C4 source) with two levels (2.5 % and 5.0 %). Sources of C decomposition (biochar derived C, primed C, and basal soil derived C) were partitioned. The percent of biochar-derived CO2 emission to the total mineralized C increased as the aggregate size decreased. The short-term positive priming effects appeared in the early stage for all three aggregate-size fractions. Predominantly negative priming effects were observed after 56 days of incubation in the bulk soils and 0.25 mm microaggregates. Furthermore, much stronger repression of soil C mineralization was induced by a higher biochar level, with 10.1-53.4 % higher negative priming effects under 5.0 % biochar treatments than 2.5 % biochar treatments over 180 days. The results suggest that a greater portion of total readily decomposable soil organic C in 0.25 mm macroaggregates has probably been protected by biochar amended and made unavailable. Our study indicates that the priming effects of biochar on the soil organic carbon in Ultisols depend on the aggregate size.

Quantitatively figuring out the effects of climate and land-use change on water resources and their components is essential for water resource management. This study investigates the effects of climate and land-use change on blue and green water and their components in the upper Ganjiang River basin from the 1980s to the 2010s by comparing the simulated changes in blue and green water resources by using a Soil and Water Assessment Tool (SWAT) model forced by five climate and land-use scenarios. The results suggest that the blue water flow (BWF) decreased by 86.03 mm year−1, while green water flow (GWF) and green water storage (GWS) increased by 8.61 mm year−1 and 12.51 mm year−1, respectively. The spatial distribution of blue and green water was impacted by climate, wind direction, topography, and elevation. Climate change was the main factor affecting blue and green water resources in the basin; land-use change had strong effects only locally. Precipitation changes significantly amplified the BWF changes. The proportion of surface runoff in BWF was positively correlated with precipitation changes; lateral flow showed the opposite tendency. Higher temperatures resulted in increased GWF and decreased BWF, both of which were most sensitive to temperature increases up to 1 °C. All agricultural land and forestland conversion scenarios resulted in decreased BWF and increased GWF in the watershed. GWS was less affected by climate and land-use change than GWF and BWF, and the trends in GWS were not significant. The study provides a reference for blue and green water resource management in humid areas.

The main objective of this study was to investigate the effects of abiogenic and biogenic factors, and their interaction, on aggregate stability determined at different particle sizes.

通过对不同恢复年限及恢复类型(2 a人工恢复湿地松林、5 a人工恢复湿地松林、5 a自然恢复湿地松林、5 a自然恢复荒地和6 a种植杨梅园空地)0～30 cm红砂岩发育土壤团聚体中有机碳、全磷、全氮分布规律、化学计量比及其与土壤抗蚀性的相关性进行分析,旨在探究红砂岩侵蚀劣地植被恢复过程中土壤养分变化及抗蚀性.结果表明:红砂岩纯裸地土壤养分含量较低,经过不同措施恢复后,土壤理化性质有不同程度的改善.不同类型红砂岩土壤团聚体级配不同.裸地以>5 mm粒径团聚体为主,约占60％以上.除自然恢复5a荒地以2～5 mm团聚体为主以外,其余恢复措施的红砂岩土壤均以小于0.25 mm粒径微团聚体为主.不同粒径土壤团聚体有机碳、全氮含量均随恢复年限增长呈增加趋势.C、N集中分布在0.25～1 mm团聚体上,尤其是0.5～1 mm团聚体;P则分布较为均匀.采取不同恢复措施后土壤抗蚀性有不同程度的提高,其中结构体破坏率从55.68％降至10％以下.研究区土壤C:N均值为15.0:1;C:P均值为79.7:1;N:P均值为4.0:1.由此可知不同红砂岩发育土壤随着恢复年限而增长,抗蚀性能大幅提升,由于养分主要分布在0.5～5 mm土壤水稳性的团聚体上,而该部分团聚体流失严重,导致土壤养分含量低、土壤抗蚀性差,恢复过程较为困难.

生物覆盖措施能显著降低敏感脆弱带及裸露坡地水土流失,且具有成本低、见效快等特点,适合在矿区推广.为研究稻草覆盖对稀土尾渣坡面水土流失过程的影响,采用人工模拟降雨试验,对比研究不同雨强(60和90 mm∕h)和不同稻草覆盖度(0％、50％和100％)条件下稀土尾矿地表产流、产沙情况.模拟降雨试验在位于江西省九江市德安县的江西省水土保持生态科技园开展,不同雨强采用西安清远测控技术有限公司设计的QYJY-503人工模拟降雨系统进行控制.结果表明:雨强为60 mm∕h时,50％和100％稻草覆盖度处理坡面径流开始时间分别比0％稻草覆盖度坡面延迟46％和91％;雨强为90 mm∕h时,延迟幅度分别为3.0和4.8倍.0％、50％和100％稻草覆盖度条件下稀土矿渣坡面单位时间产流量分别在产流开始后6、31和41 min达到稳定值.60 mm∕h雨强条件下稀土矿渣坡面1 h总产流量呈现0％稻草覆盖度>100％稻草覆盖度>50％稻草覆盖度(P<0.05),而90 mm∕h雨强条件下则为0％稻草覆盖度>50％稻草覆盖度>100％稻草覆盖度(P<0.01).雨强为60 mm∕h时,50％和100％稻草覆盖度稀土矿渣坡面土壤侵蚀量分别比0％稻草覆盖度坡面降低73.46％和84.53％;而雨强为90 mm∕h时,2种措施土壤侵蚀量降幅分别为54.83％和72.14％.研究显示,稻草覆盖措施可以有效降低矿区土壤坡面径流、泥沙产量.

A field scouring experiment was conducted in red soil hilly region to study the characteristics of drainage and sediment transport of cement ditch, earth ditch and grass ditch.The results suggested the start time and cut-off time of runoff for different ditches were significantly different(P<0.05).The start time and cut-off time of runoff for three ditches decreased in an order of cement ditch,earth ditch and grass ditch.With the increase of the scour flow, the start time decreased, but the cut-off time showed no significant variation trend.Secondly, the descend order of the drainage velocity in different ditches was cement ditch, soil ditch and grass ditch.The drainage flow velocity of the cement ditch and the earth ditch increased at first and then tended to be stable with the increase of the distance from the slope section, but drainage velocity in grass ditch decreased.With the increase of scour flow from 6 L/min to 12 L/min, the average drainage velocity in cement ditch, soil ditch and grass ditch increased by 14%, 32% and 40%, respectively.Drainage per unit time in the cement ditch was highest, followed by the earth ditch, and the grass ditch was lowest.With the increasing of scour flow, total runoff increased.The runoff process firstly increased and then tended to be stable in all of ditches.Lastly, there are significant differences in sediment yields among different ditches.The sediment load decreased in an order of cement ditch, earth ditch and grass ditch.As scour flow increased, the sediment yields in all ditches increased.The drainage and sediment load of different ditches were significantly different in the red soil hilly region.

The surface and subsurface runoff in the red soil slope farmland result in soil moisture and nutrient loss. In addition, the surface and subsurface runoff are important components contributing runoff at the watershed scale. An extensive literature shows that rain intensity and slope are two main factors playing an important role in the surface and subsurface runoff. In this paper, the surface and subsurface runoff in the red soil slope land under different rainfall intensities and slopes were studied by stimulated rainfall experiments in the flume (3.0 m length×1.0 m width×0.5 m depth) with variable slopes. The experiments were conducted in the Jiangxi Soil and Water Conservation Ecological Science and Technology Park. Stratified soil samples from different profiles including 0-20 cm (the plow horizon) and 20-40 cm (the plow pan) were collected and then filled respectively into the flumes by controlling the bulk density. For the rain intensity of 90 mm/h, we set four slopes including 5°, 10°, 15° and 20° in the simulated rainfall experiment. Three rain intensity levels (30, 60 and 90 mm/h) were set for the plots with slope of 10°. The results indicated that: 1) the subsurface runoff lagged behind the surface runoff, and the initiation time of the surface and subsurface runoff decreased with the increase of rainfall intensity from 30 mm/h to 90 mm/h. The lag time of the subsurface runoff initiation increased with the increasing rain intensity, and then tended to be stable; 2) the initial and steady surface runoff increased with the increase of the rain intensity; and the initiation subsurface runoff intensity increased with the increase of rainfall intensity. An increase trend was observed in the runoff produced by per unit rainfall; 3) the initial intensity of the surface runoff increased with the increase of rainfall intensity from 30 to 90 mm/h. However, no significant differences were found for the peak values of the subsurface runoff under different rainfall intensities. The attenuation curves of the surface runoff under different rainfall intensities were similar; 4) the obvious differences were observed between the runoff process curves of the surface runoff and subsurface runoff. The surface runoff increased firstly and then tended to be stable, but the soil subsurface runoff increased firstly and then decreased; 5) the initiation time of the surface runoff decreased with the increase of slope from 5° to 20°, but the initiation time of the subsurface runoff decreased firstly and then increased with the increase of the slope. The lag time of the subsurface runoff to the surface runoff also decreased firstly and then increased with the increasing slopes; 6) the surface runoff intensity first increased and then decreased with the increasing slope from 5° to 20° with a critical slope of 10°. The peak values of the subsurface runoff in soils increased firstly and then decreased with the increasing slopes. Moreover, the time to reach the peak value of the subsurface runoff decreased gradually with the increase of the slopes.

Purpose The main objective of this study was to conduct a preliminary comparison on the trace element pollution, sequential extraction, and risk level in different depths of tailings with different accumulation age from a rare earth mine in Jiangxi Province, China. Materials and methods We collected samples at different depths of rare earth tailings with 1- and 5-year accumulation age in the same rare earth mine. The total concentrations of six potentially toxic elements (Pb, Cd, Cr, Cu, Ni, and As) were determined by acid digestion and the chemical fractionation of Pb and Cd were analyzed using the modified sequential extraction procedure (SEP) proposed by the Community Bureau of Reference (BCR) in combination with inductively coupled plasma mass spectrometry (ICP-MS). A preliminary comparison on the trace element pollution, sequential extraction, and risk level in different depths of rare earth tailings with diverse accumulation age was then conducted. Results and discussion High pollution levels were observed for Pb and Cd, with total concentrations in the range 79.33~134.54 and 0.83~1.83 mg kg −1 , respectively. However, low pollution levels were found for Cr, Cu, Ni, and As. For the concentrations of total Pb and Cd, Pb and Cd associated with the Fe–Mn oxides and the residual fraction from top to bottom layers decreased predominantly. Overall, for the concentrations of total Pb and Cd, Pb and Cd associated with the residual fraction in all depths of the mine tailings with 5-year accumulation age were much higher than those in the mine tailings with 1-year accumulation age. The rare earth tailings showed low risk for Pb with risk assessment code (RAC) values less than 10%, but medium risk for Cd showed in the rare earth tailings with 5-year accumulation age at all depths and in the rare earth tailings with 1-year accumulation age at 10~20- and 20~30-cm depths. Conclusions Advances made in our understanding of trace element pollution, sequential extraction, and risk level in different depths of tailings with different accumulation age are providing new evidences for the transportation of contaminants that derive from mining activities.

基于江西省5个气象站(赣县、吉安、南城、南昌、景德镇)近50a(1961～2010年)平均气温、最高、最低平均气温、相对湿度、风速、日照时数、降雨量等逐月平均资料,计算江西省干旱侦测指数(Reconnaissance drought index,RDI),分析旱情、涝情变化趋势.同时,运用多元回归法分析主要驱动因素.研究结果表明,1961～2010年江西省年及四个季节的降雨量、平均相对湿度与RDIst值均呈现极显著的正相关关系(p＜0.01),而日照时数则与RDIst值呈现极显著的负相关关系(p＜0.01).降雨量对江西省旱、涝变化的贡献率最大,为42％～58％;其次是平均气温和相对湿度,分别为11％～19％和7％～19％;平均风速和日照时数对江西省旱、涝变化的贡献率较小.降雨量、相对湿度的增加,日照时数的减少共同导致了1961～2010年江西省年际尺度和春季RDIst值的增加,表明江西省总体从偏旱向偏涝转变.1961～2010年江西省夏季、秋季和冬季RDIst没有明显的增长或降低趋势.

采用野外径流小区实验,以自然裸露坡地为对照,利用2013年赣北第四纪红壤坡地的降雨和产流过程数据,在分析日降雨特征的基础上,研究了不同植物措施对次降雨条件下的坡面产流峰值及年产流量的消减效果.结果表明:(1)全年侵蚀性降雨季节分布不均,主要集中在3-6月份,降雨量占全年的80.3％,且暴雨及大暴雨多发;(2)降雨量及最大时段侵蚀性雨强I60对坡面产流量有显著的影响,坡面产流量与PI60呈极显著的线性相关关系;(3)不同植物措施对坡面最大时段径流峰值及年总径流深的消减效果,以柑橘+百喜草全园覆盖措施为最好,其次为柑橘+百喜草带措施,柑橘纯林则最差.