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1.
黄土丘陵区沙打旺草地土壤水分过耗与恢复   总被引:14,自引:3,他引:11  
程积民  万惠娥  王静  雍绍萍 《生态学报》2004,24(12):2979-2983
研究了黄土丘陵区沙打旺 (Astragalusadsurgens)草地土壤水分的动态规律和恢复过程及人为调控土壤水分的效果。结果表明 :沙打旺在该区生长年限为 6~ 7a,生物量形成的高峰期在第 3~ 4年 ,之后土壤水分大量亏缺 ,生物量逐年下降 ,第 6年生物量和水分均下降到最低点。同时土壤水分的消耗深度与根系的分布相一致 ,土壤干层主要集中在根系分布的密集区 0 .3~0 .8m。随着沙打旺生长年限的延长及根系的下扎 ,土壤干层逐渐加深 ,3~ 6年生沙打旺草地土壤干层平均厚度为 2 .3m;土壤水分要自然恢复到种植前的含水量需要 6~ 7a;通过水平阶和水平沟整地进行人工调控 ,土壤水分比自然恢复可提前 2~ 3a,一般需要 4~ 5 a的时间即可恢复正常  相似文献   

2.
黄土高原半湿润区苜蓿草地土壤干层形成及水分恢复   总被引:6,自引:0,他引:6  
研究了黄土高原地区不同生长年限苜蓿草地0~1000 cm土层土壤水分消耗规律.结果表明,荒地与苜蓿草地土壤干层出现的区域及发生的程度不同:荒地在80~100 cm土层深度,出现轻度干层;生长年限低于8a(含8a)的苜蓿草地,在250~350 cm土层出现轻度干层,生长年限超过8a,出现中度干层,干层范围延至500 cm土层以下.苜蓿生长超过18a,0~200 cm上层土壤水分开始恢复,年均恢复1.49%;但在200~1000 cm土壤深层,18、26年生苜蓿草地土壤含水量仅为10.20%,深层土壤通体干化,水分难以恢复.  相似文献   

3.
实地测定了黄土高原半干旱区固原不同生长年限苜蓿草地和连作8a苜蓿草地翻耕轮作不同年限粮食作物后深层土壤水分特征,分析了苜蓿草地土壤干燥化特征和粮草轮作对土壤水分的恢复效应.结果表明:(1)苜蓿连作1a、5a、8a和12a等4类苜蓿草地0~1000cm土层平均土壤湿度值为6.6%,平均土壤水分过耗量702.8mm,平均土壤干燥化速率147.1mm/a,达到强烈干燥化程度,苜蓿连作5a土壤干层深度超过1000cm,苜蓿连作8a土壤干层深度超过1360cm,苜蓿草地合理利用年限为7a.(2)连作8a苜蓿草地翻耕并轮作4~7a和25a粮食作物等5类粮田0~1000cm土层土壤湿度介于6.74%~11.95%,土壤贮水量恢复值介于210.6~887.3mm,平均土壤水分恢复速率为80.8mm/a.轮作6a后粮田土壤干层轻度恢复程度以上深度达到1000cm.通过粮草轮作使苜蓿草地土壤湿度恢复到当地土壤稳定湿度需要13a以上.黄土高原半干旱区适宜的粮草轮作模式为:7a苜蓿→13a粮食作物.  相似文献   

4.
以各类作物农田水分为对照,连续两年对宁南山区不同生长年限苜蓿深层土壤水分以及10年生苜蓿地耕翻后轮作不同年份作物农田的水分进行了测定.结果表明,随着苜蓿生长年限的增加,干层深度与厚度先增加后减小.3年生苜蓿干层深度为720cm,6年生干层最深可达1000cm以下,10年生干层深度为920cm,3~12年生苜蓿地0~700cm土层基本上均属于土壤干层范围.苜蓿地0~800cm土壤湿度随生长年限增加而降低,2004年测定的4、7年生和12年生苜蓿地0~700cm土层平均含水率分别为5.30%、5.22%和5.01%;2005年测定的3、6年生和10年生苜蓿地0~800cm土层湿度分别为6.26%、5.60%和5.27%;而800~1000cm土层湿度在一定年限后有恢复趋势.300cm为苜蓿地降水下渗的最大临界深度,300cm以下土壤干层一旦形成,将长期存在,7~12年生苜蓿300~700cm土层湿度仅维持在4.0%左右.苜蓿地和农田的土壤干层厚度与湿度有较大差异,草粮轮作可使苜蓿土壤干层水分基本恢复到农田湿度,而且轮作年份越长,土壤各层次水分恢复效果越好,10年生苜蓿轮作18年后土壤水分基本恢复到农田状态.  相似文献   

5.
宁南半干旱与半干旱偏旱区苜蓿草地土壤水分与养分特征   总被引:1,自引:0,他引:1  
任晶晶  李军  王学春  方新宇 《生态学报》2011,31(13):3638-3649
通过对宁夏南部半干旱区(固原)和半干旱偏旱区(海原)不同生长年限紫花苜蓿(Medicago sativa L.)草地深层土壤水分与养分含量的测定,分析和比较了2种干旱类型区苜蓿草地土壤水分与养分差异及其土层剖面的分布特征。结果表明:(1) 2个类型旱区苜蓿草地0~1000 cm土层平均土壤湿度随生长年限的延长逐渐降低,但草地衰败后对水分的消耗减少。(2) 随土层深度的增加,2个类型旱区苜蓿草地土壤湿度表现出先减少后增加的变化趋势;有机质、全氮、碱解氮和速效磷含量不断减少。(3) 随生长年限的延长,2个类型旱区苜蓿根系对土壤水分和养分的消耗不断加深,6 a苜蓿草地土壤含水量、碱解氮和速效磷发生了不同程度的亏缺;10 a苜蓿草地均已进入衰败期,土壤有机质、全氮和碱解氮自上而下逐渐恢复,且半干旱偏旱区恢复的较快;速效磷含量随生长年限的延长不断减少,苜蓿草地衰败后消耗速率减小。(4) 半干旱偏旱区相同生长年限苜蓿草地0~400 cm土层土壤养分含量均高于半干旱区。(5)土壤水分亏缺与养分不均衡导致苜蓿草地衰败。因此,在实际生产中对旱地苜蓿草地应进行合理灌溉与施肥,平衡土壤养分并延缓草地衰败。  相似文献   

6.
研究了陇中黄土高原半干旱区不同种植年限紫花苜蓿地土壤水分特征及适宜种植年限.结果表明: 3、8、12和14年生苜蓿地0~300 cm土层土壤平均含水量均明显低于当地土壤稳定湿度值.12和14年生苜蓿地0~300 cm土层土壤含水量仅为9.2%和7.1%,甚至低于作物有效水分下限.1、3、8、12和14年生紫花苜蓿地0~300 cm土层干燥化指数分别为125.4%、30.5%、18.4%、-34.2%和-83.3%,除1年生苜蓿地土壤无干燥化现象之外,其余种植年限苜蓿地土壤均呈不同程度的干燥化.随苜蓿种植年限的延长,土壤干燥化程度加剧,但干燥化速率呈减缓趋势.综合苜蓿生产力动态和土壤水分状况,该区紫花苜蓿适宜的种植年限为8~10 年.  相似文献   

7.
黄土高原不同干旱类型区苜蓿草地深层土壤干燥化效应   总被引:27,自引:3,他引:24  
田间实地测了黄土高原不同干旱类型区不同生长年限苜蓿草地0~1000cm土层土壤湿度,分析和比较了各类苜蓿草地深层土壤干燥化效应特征。结果表明,在半湿润区、半干旱区和半干旱偏旱区,各类苜蓿草地土壤湿度平均值分别为10.84%、7.07%和5.45%,明显低于当地土壤稳定湿度值和荒草地土壤湿度值,土壤水分过耗量分别为540.2、641.1mm和455.0mm,平均土壤干燥化速度分别为61.2、101.9mm/a和99.0mm/a;3种类型区各类苜蓿草地年降水入渗深度分别为187.8、144cm和173cm,降水入渗深度以下深层土壤湿度保持稳定的干燥化状态;土壤干燥化强度随苜蓿草地生长年限延长而加剧,3年生苜蓿草地为中度干燥化强度,土壤干层厚度达到500~760cm,4年生以上苜蓿草地已达到严重干燥化和强烈干燥化强度,土壤干层厚度超过940~1000cm;通过粮草轮作使苜蓿草地土壤湿度恢复到当地土壤稳定湿度分别需要6、11a和18a以上。  相似文献   

8.
黄土高原水蚀风蚀交错区植被地上生物量及其影响因素   总被引:6,自引:0,他引:6  
Wang JG  Fan J  Wang QJ  Wang L 《应用生态学报》2011,22(3):556-564
采用野外调查的方法,于2009年9月下旬测定了六道沟小流域不同土地利用方式下的地上生物量以及土壤水分含量和养分含量,研究了水蚀风蚀交错区典型小流域植被地上生物量水平及其影响因素.结果表明:六道沟小流域主要植被地上干生物量在177~2207g·m-2;其中,玉米、谷子、弃耕地、人工草地、天然草地和灌木地的地上干生物量分别为2097~2207、518~775、248~578、280~545、177~396和372~680 g·m-2.农田平均土壤含水量(0~100 cm土层)最高,达14.2%,灌木地最低,为10.9%;弃耕地土壤水分含量的变异系数最大,为26.7%,说明弃耕地土壤水分有很强的空间异质性.土壤平均储水量大小顺序为:农田>人工草地>弃耕地>天然草地>灌木地,苜蓿地和柠条地出现土壤干化现象.植被地上干生物量与0~100 cm土层土壤储水量存在显著正相关关系(r=0.639,P<0.05),地上鲜生物量与植被的株高呈极显著正相关,较高植被的地上生物量可以间接控制水蚀风蚀交错区土壤侵蚀.植被地上生物量与土壤水分、养分具有很高的相关性,但与海拔、坡度、坡向、容重等的相关性不显著.  相似文献   

9.
 研究了黄土丘陵区垄沟集雨技术对紫花苜蓿(Medicago sativa)人工草地生产力以及土壤水分的影响。垄和沟的宽度均为30或60 cm,且垄上覆膜的处理水分利用效率分别比平作对照显著提高了13%和41%。垄和沟的宽度均为30 cm且垄上覆膜的处理4年的干草产量和平作对照无显著差异,而垄和沟的宽度均为60 cm,且垄上覆膜的处理干草产量比平作对照显著提高了41%,并且使紫花苜蓿草地产草高峰期提早了1~2年。垄和沟的宽度均为30 或60 cm,且垄面裸露的两个处理产草量比平作对照有不同程度的降低。紫花苜蓿草地生长的第三年,深度为150 cm左右的土层是降水补充和水分消耗的平衡点。所有处理在紫花苜蓿生长4年后,200~500 cm 深度的土壤水分已经接近萎蔫系数。  相似文献   

10.
张静  赵成章 《生态学杂志》2013,32(2):266-270
密度梯度对植物生物量分配格局的制约影响到混播草地在生态和生产上表现.2010年6-9月采用取代系列实验方法,在石羊河上游建立1年生人工混播草地,按燕麦(Avena sativa L.)与毛苕子(Vicia villosa Roth)的密度比例设置A(8∶2)、B(6∶4)、C(5∶5)、D(4∶6)和E(2∶8)5个处理,研究了密度对燕麦与毛苕子生物量分配格局的影响.结果表明:混播草地中随着燕麦相对密度的减小和毛苕子相对密度的增大,燕麦根系生物量先减小后增大最后再减小的趋势与毛苕子相反,燕麦和毛苕子茎、叶生物量先减小后增大;随着牧草的生长,5种混播草地中燕麦和毛苕子茎生物量分配比例逐渐增加,叶、根生物量分配比例逐渐减少.密度制约下混播牧草资源分配策略发生的调整,证明了植物地上部分对光竞争的不对称性和地下部分对资源竞争的对称性,毛苕子攀援生长及其对燕麦茎秆的压力使植物茎秆生物量分配比例较高,实现了资源利用的最大化.  相似文献   

11.
Question: How do species traits respond to environmental conditions and what is their effect on ecosystem properties? Location: Salt marshes, Northwest Germany. Methods: On 113 plots along the German mainland coast and on one island, we measured environmental parameters (soil nutrient content, inundation frequency, groundwater level and salinity), collected traits from 242 individuals (specific leaf area [SLA], whole plant C:N ratio, and dry weights of plant organs) and sampled above‐ground biomass as an ecosystem property. We constructed a path model combining environmental parameters, functional traits at community level and above‐ground biomass, which was tested against a dependence model using path analysis; model fit was evaluated by structural equation modelling (SEM). Results: The final model showed good consistency with the data and highlights the major role of groundwater level, salinity and nutrient availability as the most important factors influencing biomass allocation in salt marshes. Above‐ground living biomass was mostly determined by stem biomass, which was mediated through an allometric allocation of biomass to all other plant organs, including leaf mass. C:N ratio and SLA were the major drivers for dead biomass. Conclusion: We emphasize an indirect link between standing biomass and environmental conditions and recognize stem biomass, plant C:N ratio and SLA as keystone markers of species functioning in determining the relationship between environment and ecosystem properties.  相似文献   

12.
不同土壤水分胁迫下沙漠葳的生长及生物量的分配特征   总被引:16,自引:5,他引:11  
将从美国西部引进的2年生的沙生灌木沙漠葳(Chilopsis linearis)分别盆栽于含水量不同的土壤中,研究其生长及生物量的分配特征.结果表明,土壤水分胁迫严重限制了沙漠葳的营养生长和生殖生长,使单株叶片数、分枝数和侧根数显著下降,生物量大大降低,其中中度和重度胁迫下沙漠葳的干重分别比轻度胁迫降低40.9%和76.4%.重度土壤水分胁迫下沙漠葳的单叶干重、单叶面积和单位叶面积干重分别比轻度土壤水分胁迫降低63.45%、47.39%和27.23%,比叶面积和根茎比分别上升22.28%和86%.随土壤水分胁迫的加重,光合物质的积累从中下部叶片向中上部叶片转移.各构件生物量随土壤水分胁迫的加重而降低,其幅度大小为叶生物量>茎生物量>主根生物量>侧根生物量,反应了沙漠葳对土壤水分胁迫响应的整体行动.  相似文献   

13.
Many arid and semiarid areas of the world remain barren due to the lack of water even though the use of ephemeral local water sources, such as runoff water, could change the biomass production patterns. The objective of the present study was to determine the effects of levels of water application and modes of application on the biomass below and above ground development of mature Acacia saligna (Labill.) H.L. Wendl. shrubs. The application treatments were: flooded once a year, low and high frequency irrigation with and without an additional annual flooding, and well-watered. An analysis of the standing biomass data after 5 years of growth indicated that the yearly runoff floods contributed significantly to increase the total above ground biomass. The data collected during the 1999 season, indicated however that during this season flooding had no significant effect on any of the measured growth parameters, while application frequency had a significant effect on the growth rates, water use efficiency and leaf and stem production of shrubs. Below ground, two periods of root growth were observed for the higher irrigation frequency treatments: an initial moderate increase followed by a rapid reduction. The period of rapid reduction in root biomass matched well with the period of rapid increments in above ground biomass production. Furthermore, increased irrigation frequencies resulted in bigger root systems but for lower irrigation frequencies rooting depth increased.  相似文献   

14.
Perennial grass systems are being evaluated as a bioenergy feedstock in the northern Great Plains. Inter-annual and inter-seasonal precipitation variation in this region will require efficient water use to maintain sufficient yield production to support a mature bioenergy industry. Objectives were to evaluate the impact of a May–June (early season) and a July–August (late season) drought on the water use efficiency (WUE), amount of water used, and biomass production in monocultures of switchgrass (Panicum virgatum L.), western wheatgrass (Pascopyrum smithii (Rydb.) Á. Löve), and a western wheatgrass–alfalfa (Medicago sativa L.) mixture using an automated rainout shelter. WUE was strongly driven by biomass accumulation and ranged from 5.6 to 7.4 g biomass mm?1 water for switchgrass to 1.06 to 2.07 g biomass mm?1 water used with western wheatgrass. Timing of water stress affected WUE more in western wheatgrass and the western wheatgrass–alfalfa mixture than switchgrass. Water deficit for the western wheatgrass–alfalfa mixture was 23 % lower than western wheatgrass (P?=?0.0045) and 31 % lower than switchgrass (P?<?0.0001) under the May–June stress water treatment, while switchgrass had a 37 and 38 % greater water deficit than did western wheatgrass or western wheatgrass–alfalfa mixture, respectively (P?<?0.001) under the July–August water stress treatment. Water depletion was always greatest in the upper 30 cm. Switchgrass had greater WUE but resulted in greater soil water depletion at the end of the growing season compared to western wheatgrass and a western wheatgrass–alfalfa mixture which may be a concern under multi-year drought conditions.  相似文献   

15.
Phoenix  G.K.  Gwynn-Jones  D.  Lee  J.A.  Callaghan  T.V. 《Plant Ecology》2000,146(1):67-75
The effects of ultraviolet-B radiation on regeneration after disturbance of a natural sub-arctic heathland have been investigated. Areas of pristine dwarf shrub heath were denuded of all above ground biomass in 1992 and exposed to enhanced UV-B (simulating a 15% depletion of the ozone layer). The resulting regenerated stem and leaf growth parameters were measured after four years on three dwarf shrubs, Vaccinium myrtillus, V. uliginosum and V. vitis-idaea and the grass Calamagrostis lapponica; leaves of the three dwarf shrubs were also analysed for UV-absorbing compounds and carbohydrates. Regeneration irrespective of treatment was slow, with Empetrum hermaphroditum failing to regenerate at all. Vaccinium myrtillus showed the most rapid regeneration attaining much of its original biomass in four years. There was a significant interaction between UV-B and year of regeneration in V. myrtillus; annual stem length increment showed an initial stimulation of 75% under enhanced UV-B in the first year of regeneration while a reduction of 16% was observed in the fourth year. Both V. uliginosum and V. vitis-idaea showed a reduction in annual stem length increment as regeneration progressed with a greater than 50% reduction in stem increment in the fourth year of regeneration compared to the first. Vaccinium uliginosum also showed an initial reduction in stem length increment of 40% under enhanced UV-B. None of the species were affected by enhanced UV-B in terms of total regenerated stem and leaf biomass or UV-absorbing compounds in regenerated leaf tissue. Total leaf carbohydrate and the ethanol/water soluble fraction in V. uliginosum were significantly increased by 29% and 31% respectively under enhanced UV-B. This suggests either a stimulation of photosynthesis or a reduction in sink size for photo-assimilates. Results are discussed in the context of the extremely slow regeneration of sub-arctic heath communities and the implications of contrasting UV-B effects on the regenerative ability of different species.  相似文献   

16.
黄土高原北部人工灌草植被土壤干燥化过程研究   总被引:7,自引:0,他引:7  
刘丙霞  任健  邵明安  贾小旭 《生态学报》2020,40(11):3795-3803
黄土高原北部水蚀风蚀交错区是典型的生态脆弱区,人工灌草植被土壤干燥化发生频繁。土壤干化层的形成影响生物小循环并削弱水文大循环,严重制约植被建设成效和区域生态稳定。为阐明人工灌草植被土壤干燥化过程,并确定适宜的种植年限,选择该区典型人工灌草植被—柠条和苜蓿为研究对象,分析两种植被土壤水分和地上生物量随生长年限的变化特征。结果表明:2—8年生柠条和1—7年生苜蓿对剖面土壤水分消耗强烈,并随生长年限呈快速下降趋势,9—12年生柠条和8—11年生苜蓿1.0—4.0 m剖面含水量分别降低至8.2%—9.0%和8.5%—10.5%之间,并处于相对稳定状态。4—5年生柠条地1—1.4 m开始产生干层,6年生柠条地干层深度达2.4 m,干层厚度为1.4 m;9—12年生柠条地干层深度超过4.0 m。2—4年生苜蓿地无干燥化;5年生苜蓿生长季末土壤干层深度达3.6 m,干层厚度为2.6 m,且7年生以后土壤干层的深度超过4.0 m。因此,为调控土壤干层,减少深层土壤干化的发生,建议柠条和苜蓿的生长年限分别不要超过6年和5年,其对应的地上最大干生物量分别为5050 kg/hm~2和1980 kg/hm~2。研究结果可为黄土高原北部生态脆弱区人工灌草植被管理与土壤干层调控提供科学依据。  相似文献   

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Impacts of salinity become severe when the soil is deficient in oxygen. Oxygation (using aerated water for subsurface drip irrigation of crop) could minimize the impact of salinity on plants under oxygen-limiting soil environments. Pot experiments were conducted to evaluate the effects of oxygation (12% air volume/volume of water) on vegetable soybean (moderately salt tolerant) and cotton (salt tolerant) in a salinized vertisol at 2, 8, 14, 20 dS/m ECe. In vegetable soybean, oxygation increased above ground biomass yield and water use efficiency (WUE) by 13% and 22%, respectively, compared with the control. Higher yield with oxygation was accompanied by greater plant height and stem diameter and reduced specific leaf area and leaf Na+ and Cl-concentrations. In cotton, oxygation increased lint yield and WUE by 18% and 16%, respectively, compared with the control, and was accompanied by greater canopy light interception, plant height and stem diameter. Oxygation also led to a greater rate of photosynthesis, higher relative water content in the leaf, reduced crop water stress index and lower leaf water potential. It did not, however, affect leaf Na+ or Cl- concentration. Oxygation invariably increased, whereas salinity reduced the K+ : Na+ ratio in the leaves of both species. Oxygation improved yield and WUE performance of salt tolerant and moderately tolerant crops under saline soil environments, and this may have a significant impact for irrigated agriculture where saline soils pose constraints to crop production.  相似文献   

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