Response of Artificial Grassland Carbon Stock to Management in Mountain Region of Southern Ningxia, China

Grassland is a major carbon sink in the terrestrial ecosystem. The dynamics of grassland carbon stock profoundly influence the global carbon cycle. In the published literatures so far, however, there are limited studies on the long-term dynamics and influential factors of grassland carbon stock, including soil organic carbon. In this study, spatial-temporal substitution method was applied to explore the characteristics of Medicago sativa L. （alfalfa） grassland biomass carbon and soil organic carbon density （SOCD） in a loess hilly region with different growing years and management patterns. The results demonstrated that alfalfa was the mono-dominant community during the cutting period （viz. 0-10 year）. Community succession began after the abandonment of alfalfa grassland and then the important value of alfalfa in the community declined. The artificial alfalfa community abandoned for 30 years was replaced by the S. bungeana community. Accordingly, the biomass carbon density of the clipped alfalfa showed a significant increase over the time during 0-10 year. During 0-30 year, the SOCD from 0-100 cm of the soil layer of all 5 management patterns increased over time with a range between 5.300 ± 0.981 kg/m2 and 12.578 ± 0.863 kg/m2. The sloping croplands had the lowest SOCD at 5.300 ± 0.981 kg/m2 which was quite different from the abandoned grasslands growing for 30 years which exhibited the highest SOCD with 12.578 ± 0.863 kg/m2. The ecosystem carbon density of the grassland clipped for 2 years increased 0.1 kg/m2 compared with the sloping cropland, while that of the grassland clipped for 10 years substantially increased to 10.30 ± 1.26 kg/m2. Moreover, the ecosystem carbon density for abandoned grassland became 12.62± 0.50 kg/m2 at 30 years. The carbon density of the grassland undisturbed for l0 years was similar to that of the sloping cropland and the grassland clipped for 2 years. Different management patterns imposed great different effects on the accumulation of biomass carbon on artificial grasslands, whereas the ecosystem carbon density of the grassland showed a slight increase from the clipping to abandonment of grassland in general.

Study on the Countermeasures of Eco-environment Conservation in the Mountainous Areas of Southern Ningxia under New Situation

Under the implementation of principal functional zoning,further promotion of western development,regional migration,new countryside construction,global warming and so on,the spatial adjustment of regional industry and its structure must be enforced.The spatial adjustment and arrangement of population and economy in the mountainous areas of southern Ningxia could create tremendous opportunity for its eco-environment conservation.Based on analysis on the opportunity and challenge of eco-environment conservation in the mountainous areas of southern Ningxia,some countermeasures of eco-environment conservation were discussed in the paper,so as to provide some theoretical references for the eco-environment conservation in the mountainous areas of southern Ningxia.

Deep Deformation Processes in the Southern Ningxia Geomorphic Belt: Insight from Two-dimensional Particle-in-cell Finite Difference Numerical Modelling

The deep lateral growth process of the plateau is a hot topic in earth science.As the growth boundary zone of the northeastern Tibetan Plateau,southern Ningxia geomorphic zone is controlled by four major arcuate fault zones(Fig.1),namely Haiyuan fault(HYF),XiangshanTianjingshan fault(XTSF),Yantongshan fault(YTSF).

The Models for the Development of Specialty Agriculture in the Hilly Areas of Southern Ningxia: Are They Truly Effective?

The development of specialty agriculture is of great significance to western China's agricultural structure adjustment,and it's an essential way for the construction of ecological agriculture in Southern Ningxia mountainous area.This paper makes a summary about the development status of specialty agriculture in Southern Ningxia Mountainous Area and put forward the basic benefit goal and problems needing attention.On this basis,the paper studies the development pattern of specialty agriculture in Southern Ningxia Mountainous Area from the aspects of production factors and industry.This paper suggests that the development pattern of specialty agriculture in Southern Ningxia Mountainous Area should combine the regional agricultural pattern and innovative organization structure pattern,demonstration agriculture and market-directing pattern,engineering agricultural pattern and enterprise-driven pattern.The development of specialty agriculture in Southern Ningxia Mountainous Area should promote the three patterns,in order to achieve the construction of ecological agriculture and agricultural structure adjustment.

PRODUCTIVITY AND WATER UTILITY FOR MAIN CROPS IN LOESSAL HILL.REGION, SOUTHERN NINGXIA

The loessal hill region in southern Ningxia is a semiarid and severe eroded area with developed agriculture and animal husbandry. It has long been an argument whether there might be more potentiality of farming and whether food production can be sustained at a level of local sufficiency.

The Variation Rule and Anomaly Features of the Available Precipitation in the Growth Period of Crops in the Middle and Southern Part of Ningxia

[ Objective] The aim was to study the available precipitation and its abnormal characteristics during the growth period of crops in the mid- dle and southern part of Ningxia. [ Methed] Through Takahashi＇s evaporation equation, linear trend analysis, Mann -Kendall, Lepage, wavelet analysis, the characteristics of available precipitation and its abnormal characteristics during its growth period in Ningxia were analyzed based on monthly precipitation （March- September）, temperature, and NCAR/NCEP reanalysis data in 9 observation stations from 1961 to 2010. E Result l In recent 50 years, the available precipitation during the growth period of crops in central drought area and south hilly area varied a lot, more in the south and less in the north. The available precipitation in these two areas was reducing and varied a lot in different ages. The available precipitation was less in the middle drought region after 1970s and in the southern hilly region after 1990s and the available precipitation in middle drought area changed significantly. The available precipitation in the two areas appeared in July, August, and September, above 76% of general growth period, while that in March, April and May was 14% lower than that in growth period. No abrupt changes in central drought area and south hilly area. There were the periods of 5 -7 a and 2 -3 a oscillations in the middle drought region, 2 -3 a and 10 -12 a oscillations in the southern hilly region. There were negative anomaly field at 500hPa height in high-precipitation years between the Baikal and the China＇s northwestern, and there were positive anomaly field in low-precipitation years. [ Cenclusion] The study provided reference for the reasonable utilization of available water resources in cen- tral and south Ningxia.

Pollen-recorded climate changes between 13.0 and 7.0 ^(14)C ka BP in southern Ningxia,China

A pollen record from Haiyuan section in the southern part of Ningxia revealed a detailed history of vegetation variation and associated climate changes during the period from^13.0 to^7.0 14 C ka BP.A steppe landscape under a moderately dry(and probably cool)condition(~12.7-~12.1 14 C ka BP)was replaced by a coniferous forest dominating the landscape under a generally wet climate from^12.1 to ~11.01 4C ka BP.This generally wet period,corresponding to the European B?lling/All?rod period,can be divided into three stages:a cool and wet stage between^12.1 and^11.4 14 C ka BP,a mild and rela- tively dry stage between^11.4 and^11.2 14 C ka BP,and a mild and wet stage between^11.2 and^11.0 14 C ka BP.The coniferous forest-dominated landscape was then deteriorated into steppe landscape (~11.0-~10.6 14 C ka BP)and further into a desert steppe landscape from^10.6 to^9.8 14 C ka BP,being correspondent to the European Younger Dryas period.After a brief episode of a cool and wet climate (~9.8-~9.6 14 C ka BP),a relatively mild and dry condition prevailed during the early Holocene(~9.6- ~7.6 14 C ka BP)and then a warm and humid climate started the mid-Holocene(~7.6-~7.2 14 C ka BP).

宁南黄土区不同人工植被类型深层土壤水分亏缺评价

【目的】开展评估不同人工植被类型深层土壤水分亏缺程度,能为区域科学合理实施植被恢复策略提供理论依据。【方法】以宁夏彭阳中庄小流域5种不同植被类型(山桃林、沙棘林、柠条林、苜蓿地,农田为对照)为研究对象,采用土壤水分相对亏缺指数(CSWDI)和干燥化指数(SDI)定量评价模型,对不同植被类型下0~1 000 cm土壤水分亏缺及干燥化程度进行定量化分析与评价。【结果】不同植被类型深层土壤水分变化特征差异明显,0~1 000 cm平均土壤水分含量呈现出农地(16.29%)>山桃林(13.06%)>沙棘林(12.22%)>柠条林(9.12%)>苜蓿地(8.08%)。在垂直剖面上,土壤水分随土层深度增加总体呈现先减小后增加再逐渐稳定的趋势。在0~1 000 cm农地基本没有水分亏缺和干层发生,山桃林、柠条林、沙棘林和苜蓿地均呈现不同程度的土壤水分亏缺现象,平均土壤水分相对亏缺指数分别为0、0.22、0.62、0.35、0.79,平均土壤干燥化指数分别为185.5%、67.45%、51.55%、87.35%、36.10%,5种植被类型中苜蓿地土壤水分亏缺最严重,其次为柠条林、沙棘林、山桃林、农地。山桃林、柠条林、沙棘林、苜蓿地均有不同程度的干层分布,分别呈现中度、轻度和严重干燥化,干层厚度(DSLT)分别为890、860、800、920 cm,DSL-SWC分别为12.42%、8.14%、11.56%、7.76%。【结论】宁南黄土区不同人工植被类型对深层土壤水分亏缺具有明显影响,导致不同程度土壤干层发生,其中苜蓿地土壤水分亏缺最严重,应采取相应措施恢复土壤水分,促进区域水土资源可持续利用和生态健康发展。

宁南山区不同植被类型土壤水分变化特征

以宁夏南部山区山杏林、沙棘林、山杏×沙棘混交林3种典型植被为试材,采用野外定位监测法,对3种植被0~100 cm不同深度土壤水分进行连续1年定位观测,研究了不同植被类型土壤水分时间变化和垂直变化规律,以期了解宁南山区主要植被类型的土壤水分状况及耗水特性。结果表明:不同植被类型土壤储水量在年内变化趋势整体呈“M”型,土壤储水量按照从大到小的排序为山杏林(158.35 mm)>山杏×沙棘混交林(139.72 mm)>沙棘林(123.24 mm)。不同植被类型日平均土壤含水量的变化动态相似,其变化趋势与降雨量密切相关,9月山杏林、沙棘林、山杏×沙棘混交林地的土壤含水量分别是8月的1.56、1.41、1.49倍;3种植被类型平均土壤含水量最大值均在10月,最小值均在8月。在垂直方向上,3种植被土壤水分的变化有一定的差异性,随着土层深度的增加,沙棘林土壤含水量呈先增加后降低的趋势,山杏林、山杏×沙棘混交林土壤含水量呈波形变化趋势;3种植被类型土壤水分的变异系数总体呈下降趋势,沙棘林各土层变异系数的均值最大,为39.36%。综上,山杏林土壤水分状况最好,其次是山杏×沙棘林,为该区域植被恢复与可持续管理提供重要参考依据。

微生物菌剂对连作芹菜根际土壤真菌群落多样性与结构的影响

以宁南旱区连作4年芹菜根际土壤为研究对象,采用田间定位试验结合高通量测序技术,以常规施肥(CK)为对照,研究常规施肥+枯草·哈茨复合菌剂(MF),常规施肥+枯草芽孢杆菌(BS),常规施肥+哈茨木霉菌(TH)3个处理对芹菜连作根际土壤真菌多样性及群落组成的影响。结果表明:施用枯草·哈茨复合菌显著提高了土壤有效磷、速效钾含量,增幅分别为34.29%和9.98%。施用微生物菌剂增加了土壤脲酶、蔗糖酶活性,平均增幅分别为43.16%和12.98%,并显著改变了土壤真菌的β-多样性。被孢霉属(Mortierella)、织球壳属(Plectosphaerella)、赤霉菌属(Gibberella)、链格孢属(Alternaria)、镰刀菌属(Fusarium)是各处理优势菌属,施用枯草·哈茨复合菌显著降低了赤霉菌属、链格孢属、镰刀霉属等真菌性病原菌的相对丰度,降幅分别为59.88%、51.63%、36.13%。冗余分析表明土壤蔗糖酶、脲酶、碱性磷酸酶活性、pH值和全磷是影响真菌群落结构组成的主要驱动因子。综合而言,枯草·哈茨复合菌剂的施用不仅降低了连作芹菜根际土壤镰刀菌属、链格孢属、赤霉菌属等病原菌的富集,还通过改变有效磷、速效钾等土壤理化性质,进一步重塑土壤真菌群落结构。

苜蓿蓟马空间动态与作物布局关系研究

【目的】明确宁夏南部山区苜蓿蓟马空间种群动态与作物环境布局之间的关系。【方法】利用高空遥感无人机获取宁夏南部山区4个研究区域的遥感图片,经处理后计算其景观格局指数,明确景观与蓟马种群动态之间的关系。【结果】离散核心区数量(NDCA)、总边界长(TE)、总面积比(CA/TA)、核心区面积均值(Core_MN)、斑块丰度密度(PRD)与蓟马发生量相关,相关系数为-0.99~0.97。【结论】南部山区在梯田、台塬上种植苜蓿,对于蓟马控制具有地形优势;蓟马在跨越高低起伏的地形上,必须依靠一定的气象条件才能顺利转移;但生境破碎化,容易造成蓟马爆发成灾。

供钾水平对宁南山区花椰菜产量及钾素平衡的影响

【目的】为宁夏冷凉花椰菜生产中钾肥合理施用提供科学依据。【方法】以宁夏冷凉主导花椰菜为试验材料,设置0(K_(0))、10(K_(10))、20(K_(20))、30(K_(30))、40 kg/667m^(2)(K_(40))5个施钾水平,通过田间试验,研究供钾对露地花椰菜产量、钾素吸收分配利用及土壤根层钾素质量与平衡的影响。【结果】供钾显著增加花椰菜产量,增产率在5.32%~16.24%,供钾水平与花球产量呈极显著的二次抛物曲线关系,最高产量为3 529.43 kg/667 m^(2),最佳供钾水平为24.28 kg/667 m^(2)。在苗期和莲座期茎叶是花椰菜钾元素的累积中心,不同处理茎叶分配比例在49.67%~90.49%,进入成熟期花球是花椰菜钾元素的累积中心,不同处理花球累积分配比例在42.25%~53.73%,整株花椰菜钾素累积量苗期以K_(30)处理最高,莲座期和成熟期均以K_(20)处理最高,较对照分别显著提高69.40%、79.38%。钾肥利用效率为21.77%~40.31%,以K20处理的钾肥利用率、贡献率及农学效率均最高,分别为45.28%,21.31%、38.670 kg/kg。供钾水平低于20 kg/667 m^(2)时,土壤钾素平衡表现为亏缺,供钾水平超过30 kg/667 m^(2)钾素盈余由负转正,再继续投入钾肥,钾素盈余。【结论】综合考虑花椰菜钾素吸收利用分配与产量和土壤钾素有效性与菜田钾素收支平衡等因素,建议宁夏南部山区花椰菜适宜的供钾水平为21.82~29.24 kg/667 m^(2)。

宁夏南部山区植被覆盖度变化及其地形因子相关性分析

以宁夏南部山区为研究区,基于Landsat影像,运用改进的像元二分模型估算1996、2008和2018年3个时相的植被覆盖度,用数字高程模型提取坡度、坡向等地形因子,分析研究区植被覆盖度的变化以及与地形因子的相关性。结果表明:研究期间,研究区植被覆盖度呈现显著增加,尤以高植被覆盖度为甚。总体来看,高程在2400 m以下的植被覆盖度随高程增加呈现上升趋势;随坡度增加,植被覆盖度呈现上升趋势;1996和2018年2个年份的植被覆盖度在各坡向差异不大,但是2008年植被覆盖度有较明显的差异,变化趋势为阴坡>半阴坡>半阳坡>阳坡。

宁南黄土区典型林草地土壤水分年际动态变化特征

以宁夏彭阳中庄小流域典型林草地(山杏林、沙棘林、苜蓿地)为供试样地,采用土壤温湿度监测仪定位监测了2020—2022年样地生长季(5—10月)0~2 m土壤体积含水量,研究了不同林草地土壤水分动态变化规律,以期为该区域林草的合理选择和水资源有效利用提供参考依据。结果表明:1)在生长季内,不同林草地土壤水分的季节变化可以划分为消耗期(5—8月)和补偿期(9—10月),平水年(2020和2021年)土壤水分波动较大,干旱年(2022年)土壤水分变化较为平缓;3年间不同林草地土壤水分均表现为山杏林>沙棘林>苜蓿地;2)不同林草地0~40 cm土壤水分易受降雨影响,季节波动性最大,40~100 cm土壤水分受降雨影响较小,季节波动性开始减弱,100~200 cm土壤水分受降雨影响最小,季节波动性相对比较稳定;3)不同林草地土壤水分剖面分布年度变化趋势是一致的,土壤水分变化均表现为平水年(2020年)>平水年(2021年)>干旱年(2022年),与年度降雨量的变化相一致。

宁南黄土区典型人工林下土壤粒径分布分形特征与养分关系研究

以宁夏彭阳中庄小流域3种典型人工林(山杏林、柠条林、沙棘林)为供试样地,以农地为对照,采用野外标准化方法采集0~100cm土壤样品,利用Mastersizer3000型激光粒度仪测定土壤粒径组成,并测定了土壤养分相关参数,研究了3种不同人工林地土壤粒径分布和分形特征及其与养分的关系,以期为宁南黄土区林地土壤健康评价和合理化经营提供参考依据。结果表明:1)3种人工林地0~100cm土层土壤颗粒以粉砂粒为主,其中柠条林和山杏林土壤粘粒含量、土壤分形维数均高于农地和沙棘林。土壤分形维数与土壤各级粒径的差异较大,与粘粒、粉粒呈极显著正相关,与砂粒呈极显著负相关,分形维数越大,所含细颗粒越多;2)3种人工林地在0~100cm土层土壤有机质、全氮、全磷、全钾、碱解氮、速效钾含量差异显著(P<0.05),总体表现为农地>柠条林>山杏林>沙棘林;土壤有机质、碱解氮、速效钾含量随土层深度的增加总体呈下降趋势,均具有明显的表聚性,全氮、全磷、全钾含量随土层深度的变化呈波动性且无明显变化规律;3)土壤分形维数与粘粒、粉粒、全磷、全钾含量呈显著正相关关系(P<0.05),与砂粒呈极显著负相关(P<0.01)。

宁夏中南部地区马铃薯水分盈亏研究

了解宁夏中南部地区马铃薯的需水规律和水分供需状况,可为合理安排补灌制度,提高水分利用率提供支持。采用FAOPM56方法和农田水分平衡方程,通过细化Kc系数,分析了马铃薯历年逐旬需水量、耗水量和水分盈亏变化。结果表明:马铃薯全生育期需水465.1~677.3mm,与气温和降水量分别呈极显著正相关和负相关,需水量在高温年偏多,低温年偏少,在多雨年偏少,少雨年偏多。苗期和块茎膨大期水分盈亏为正值,6—8月上旬大部为负值,即有7—12个旬的水分亏缺超过10mm/旬。缺水时段从南到北逐渐延长,缺水量逐渐增多,中部干旱带6—8月累积水分亏缺300mm以上。为此,可选择耐旱品种,实施低耗水前茬休耕轮作、地膜覆盖、垄沟栽培、水分亏缺期节水补灌等措施,支撑马铃薯产业可持续发展。

宁南黄土区典型林分林下草本植被根系分布特征

以宁南黄土区彭阳中庄小流域4种典型林分(山杏林、山桃林、山杏柠条林、山杏沙棘林)林下草本植被为研究对象,通过采用样方-根钻法和Win RHIZO根系分析系统对不同林地0~30 cm土层的草本根系生物量和分布特征进行了定量分析,以期揭示宁南黄土区不同人工林下草本根系分布特征,为研究区生态恢复和林分配置提供参考依据。结果表明:各林地草本总生物量、总根长密度和总根系表面积密度均表现出山杏柠条和山杏沙棘混交林较大,山杏林和山桃林较小且相差不大。根系参数主要分布于0~10 cm,随着土壤深度的增加各指标均呈现递减的趋势。0~30 cm土层不同径级的根长密度和根表面积密度基本以0~0.5 mm径级的根系分布最广,0~2 mm径级的细根所占比例较大,且随着根系直径的增加二者基本呈现下降趋势。不同土层不同径级的根长密度基本表现为0~0.5 mm>0.5~1 mm>1~2 mm>2~3.5 mm>3.5 mm。总体反映出混交林林下草本植被各根系参数相较于纯林在土壤表层占比均较高,能够有效改善表层土壤结构,提高土壤抗侵蚀性能。

垄作模式与种植密度互作对露地花椰菜生长的影响

为确定花椰菜在宁南山区露地栽培的最佳作畦模式和种植密度,设置2个不同作畦模式(2行、3行;分别编号为T、N)和3个不同种植密度(2500、3000、3500株/667 m^(2);分别编号为1、2、3)的双因素试验,比较分析不同作畦模式与密度对花椰菜植株生长、产量和品质的影响。结果表明,花椰菜生长、产量及品质指标在不同作畦模式及种植密度处理下有所不同;株幅、花球质量、花球横径、中心柱高在2行作畦且密度在2500株/667 m^(2)时最优;可溶性蛋白含量在2行作畦且密度在3000株/667 m^(2)时最优;叶片数、花球纵径在3行作畦且密度在2500株/667 m^(2)时最优;株高、外茎高、产量、维生素C含量、可溶性固形物含、可溶性糖含量在3行作畦且密度在3000株/667 m^(2)时最优。综合考虑花椰菜植株生长、产量及品质指标,主成分分析最终排名N2>T2>N3>N1>T3>T1,2行和3行作畦且密度在3000株/667 m^(2)时排名前2,且3行作畦、种植密度在3000株/667 m^(2)时效果最好,可作为宁南山区露地花椰菜高产高效栽培参考。

宁南山区杏园三种食心虫种群发生动态

为掌握宁南山区杏园食心虫发生规律,2018年和2020年采用性诱监测方法对彭阳县杏园梨小食心虫、桃小食心虫和李小食心虫成虫种群动态进行了系统监测。结果表明,宁南山区杏园梨小食心虫成虫田间发生期为4月上旬至9月中旬,发生高峰分别为4月底至5月初、5月下旬初和6月中旬末至下旬初,7月上旬后零星发生,无明显峰期。不同坡向虫口数量分布呈现东坡>南坡>西坡,不同坡向的上、中、下坡位虫口数量均以中、下层坡位分布为主。桃小食心虫成虫发生期为5月中旬或下旬至8月下旬或9月初,发生高峰分别为6月上旬或中旬初和7月中旬或下旬;李小食心虫成虫发生期为5月上旬至9月上旬,发生高峰分别为6月上旬、7月上旬和8月上旬。宁南山区对杏园3种食心虫防治可以采取以农业防治为基础,优先采用理化诱杀和生防技术,大发生时加强药剂适期防治的综合防治策略。

施磷对宁南山区花椰菜产量、磷素利用效率及平衡的影响

以花椰菜为试材,采用单因素随机区组大田试验方法,研究了施磷对露地土壤根层磷素质量、花椰菜产量、植株磷素累计分配、磷素利用效率及表观平衡的影响,以期明确宁夏南部山区冷凉花椰菜生产中最佳施磷水平。结果表明:施磷显著增加花椰菜产量,增产率在12.96%~22.08%,施磷水平与花球产量呈极显著的二次抛物曲线关系,667 m^(2)最高产量3 651.12 kg时,667 m^(2)最佳施磷水平为24.28 kg。在苗期和莲座期茎叶是花椰菜磷元素的累积中心,不同处理茎叶分配比例在69.79%~86.08%,进入成熟期花球是磷元素的累积中心,花球磷素累积比例在53.61%~72.95%,以P_(10)处理最高,比不施磷肥的P_(0)处理整株磷素累积量显著提高46.15%。磷肥利用效率为13.01%~33.78%,以P_(10)处理的磷肥利用率最高,显著高于其它处理,其磷肥贡献率为19.03 kg·kg^(-1)。667 m^(2)施磷水平小于10 kg时,土壤磷素平衡表现为亏缺,667 m^(2)施磷水平大于15 kg,磷素表观平衡呈现磷素盈余。综合考虑花椰菜产量、磷素利用及土壤磷素收支平衡等因素,建议宁夏南部山区花椰菜每667 m^(2)适宜的施磷水平为12.61~12.86 kg。