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1.
北京山区辽东栎林土壤释放CO_2的模拟实验研究 总被引:47,自引:4,他引:43
模拟北京山区辽东栎林群落,对该类型土壤释放CO2过程进行了连续3a的实验研究,结果表明:辽东栎林土壤呼吸强度平均为5.92±1.32μmolCO2m-2s-1,在不同月份中,以8月份最高,10月最低,依次为8月>7月>6月>9月>10月(P<0.05);13:00为土壤日呼吸的最高峰。温度为影响土壤呼吸的主要因子,二者存在极显著相关关系(r=0.5668,p<0.001,n=94)。据3a观测的土壤呼吸日平均值计算得出,模拟辽东栎林土壤释放CO2的通量估计范围为171.5~275.1kgCO2hm-2d-1,平均为223.3kgCO2hm-2d-1。 相似文献
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安徽虫瘟霉对桃蚜的生物测定与时间-剂量效应分析 总被引:2,自引:0,他引:2
用“孢子浴”法将人工培养的安徽虫瘟霉(Zophthoraanhuiensis)对桃蚜(Myzuspersi cae)接种而进行定量生物测定(18℃,光周期为L∶D12∶12),包括10个剂量(1.5~197.7个分生孢子/mm2),每剂量处理蚜虫64~120头,逐日观察记载死亡数至第7d。接种后第3d在高剂量处理中始见少量死蚜,第4~6d为死蚜盛期。所获数据很好地拟合时间 剂量 死亡率模型,由模型参数估计出该菌作用于桃蚜的时间效应随剂量增大而减小,在37.1~197.7个分生孢子/mm2的剂量范围内LT50值为4.5~6.7d;剂量效应在接种后随时间递减,第5~7d的LD50分别为86.8、43.7和34.1个分生孢子/mm2。结果表明,安徽虫瘟霉是一种较为理想的杀蚜微生物,在寄主体内的潜伏期为4~5d。 相似文献
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不同质地土壤的水热状况及其对冬小麦产量形成的影响 总被引:4,自引:0,他引:4
对豫东平原3种质地土壤的水热状况和冬小麦籽粒生长特征进行了研究.结果表明,冬小麦籽粒生长阶段,粘壤土5cm处的日平均温度最低,为18.3℃,砂壤土最高,为19.5℃,中壤居中,为19.1℃.3种土壤的含水量大小顺序为粘壤>中壤>砂壤,粘壤土上小麦籽粒灌浆时间最长,千粒重最高,分别为38d和45.5g,砂壤土小麦籽粒灌浆时间最短,千粒重最低,分别为33d和42.4g,中壤土小麦2项指标居中,分别为36d和43.1g.高产栽培条件下,粘壤土冬小麦产量最高,为8253kg·hm-2,中壤次之,为7980kg·hm-2,砂壤最低,为7617kg·hm-2 相似文献
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不同温湿度组合对安微虫瘟霉诱发桃蚜病害的影响 总被引:2,自引:0,他引:2
用孢子浴方法,对42批次桃蚜Myzus persicae(30-60头/批)接种大剂量(孢子79-90个/mm^2)安徽虫瘟霉Zoophthora amhuiensis的分生孢子,在20℃下保湿24h后转入不同温度(10℃、15℃、20℃、25℃、30℃及自然变温下1.5-16.6℃和8.5-20.2℃)和温度(50%、65%、80%、90%95%及100%RH)的组合条件下观察桃蚜的反应。结果表 相似文献
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稻鱼鸭复合生态经济效益的初步研究 总被引:32,自引:6,他引:26
试验表明.稻鱼鸭种养共生,水稻增产 10%以上,同时增收鲜鱼 1036.5 kg· hm-2,成鸭238.9~489.3 kg·hm-2;水稻土壤全N、P、K和有机质含量分别增加27.9、 44. 3、6. 5和 28. 2%,提高了土壤肥力;水稻植株虫口量最少.稻鱼鸭共生大大提高了稻田 的产出和效益.属良性循环的高效复合生态农业. 相似文献
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特大‘新红宝’西瓜的快速繁殖研究 总被引:5,自引:1,他引:4
利用新红宝西瓜种子、茎段、茎尖及腋芽为外植体,接种子改良的MS培养基上。种子经常规消毒灭菌后,7—15d后可获得95%以上的健壮无菌苗.苗高3cm─5cm时即可用于有关实验。接种6d后,茎段两端切口处膨大,28—35d后出现愈伤组织,出愈率达到68%。接种5d后,茎尖明显长大。在本实验的激素组合中.35d后,茎尖周围均出现了不同数量的腋芽。最好的组合为改良的MS+2.5mg/LBA+IAA1mg/L,可使一个茎尖在35—42d后扩增为18─21个芽并逐渐长成无根苗。47d后,转入改良MS+NAA0.5mg/L培养基中.生根率达到94%以上。28d后,将苗移到田间,第一批移苗500株,成活438株,成活率达到87.6%。 相似文献
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辽北平原苏打盐渍土增施泥炭对土壤盐分的影响 总被引:8,自引:0,他引:8
对辽河北部平原苏打盐渍化土壤改良试验表明,在增施泥炭条件下,苏打草甸盐土当年玉米产量可达2500~4400kg·hm-2,苏打碱化草甸土为5500~6800kg·hm-2,增产率分别为40~144%和127~181%;第2年后者的持续产量为6200~8000kg·hm-2,增产率仍高达69~118%.相应地,土壤剖面特别是耕作层呈现为明显脱盐,pH及碱化度下降,土壤有机质、全氮及全磷含量增加. 相似文献
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沈阳样区土壤与景观关系的研究 总被引:2,自引:0,他引:2
土壤是连续分布在地球陆地表面的自然客体,其发生发展与景观密不可分.在野外调查的基础上,对辽宁沈阳样区100个土壤剖面形态特征、颗粒组成、化学特征等进行对比研究,按照《中国土壤系统分类(修订三稿)》的标准,共划分出淋溶土、雏形土与新成土3个土纲和续分的5个亚纲、7个土类、9个亚类、9个土族、14个土系.土壤性质和类型与景观特征有很好的对应关系,土壤性质是地形部位、母质基础、水分状况等景观要素的综合体现,也是长期气候等环境变化与人为活动影响的综合结果. 相似文献
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Impacts of litter and understory removal on soil properties in a subtropical Acacia mangium plantation in China 总被引:5,自引:0,他引:5
In forest ecosystems, the effects of litter or understory on soil properties are far from being fully understood. We conducted
a study in a pure Acacia mangium Willd. plantation in southern China, by removing litter or understory or both components and then comparing these treatments
with a control (undisturbed), to evaluate their respective effects on soil physical, chemical and biological properties. In
addition, a litter decomposition experiment was conducted to understand the effects of understory on litter decomposition.
Our data showed that the presence of understory favored litter decomposition to a large extent. In 1 year, 75.2 and 37.2%
of litter were decomposed in the control and understory removal treatment (UR), respectively. Litter had a profound significance
in retaining soil water and contributing to soil fertility, including organic matter (OM), available phosphorus (P) and alkali-hydrolyzable
nitrogen (N), but understory exerted less influence than litter on soil physical and chemical properties. Both litter and
understory played an important role in soil biological activity as indicated by microbial biomass carbon (MBC), while there
were no significant impacts on soil exchangeable potassium (K) after either or both were removed. Contrary to our hypothesis,
the effects of understory or litter removal were not always negative. A significant soil pH increase with litter removal was
a positive factor for acid soil in the studied site. Except for soil moisture, significant effects, caused by removal of litter
or/and understory, on measured soil chemical characteristics were only observed in the top 10 cm soil layer, but not in the
10–20 cm layer. Soil available P and exchangeable K contents were significantly higher in the rainy season than in the dry
season, however, for the other soil properties, not substantially affected by season. 相似文献
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Modeling soil detachment rates at the regional scale is important for better understanding of the processes of erosion and the development of erosion models. Soil erodibility is an important factor for predicting soil loss, but its direct measurement at the watershed scale is difficult, time-consuming and costly. This study used stepwise multiple-linear regression (MLR) and artificial neural networks (ANNs) to model Water Erosion Prediction Project (WEPP) soil erodibility parameters, including the baseline inter-rill erodibility (Kib), baseline rill erodibility (Krb) and critical shear stress (τcb) of cropland conditions in calcareous soils of northwest Iran. Simulated inter-rill and rill erosion experiments were conducted at 100 locations with three replications. Kib, Krb and τcb and basic soil properties were measured at each location. Auxiliary variables related to soil erodibility were derived from a Landsat 7 satellite image and a 30 m × 30 m digital elevation model (DEM). MLR and ANN models were employed to predict Kib, Krb and τcb using two groups of input variables: i) more easily measurable basic soil properties (pedo-transfer functions (PTFs)) and ii) more easily measurable basic soil properties and auxiliary data (soil spatial prediction functions (SSPFs)). The results indicated that the WEPP models performed poorly in comparison to the derived models. PTFs and SSPFs generated from ANN models provided more reliable predictions than the MLR models. ANN-based SSPF models yielded the best results (with the highest R2 and lowest RMSE values) for predicting Kib and Krb. ANN-based PTF model performed reasonably well for predicting τcb. These results show that information from terrain attributes and remote sensing data are potential auxiliary variables for improving prediction of soil erodibility parameters. 相似文献
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除草剂阿特拉津对土壤脲酶活性的影响 总被引:15,自引:1,他引:14
研究了阿特拉津对4种典型施肥处理的土壤脲酶活力的影响。结果表明,处理初期,低浓度阿特拉津对土壤脲酶有一定刺激作用,高浓度处理在整个试验过程中对脲酶有明显抑制作用,阿特拉津对不同肥力土壤中脲酶的影响有明显差异,对照土壤和NPK肥土壤中脲酶活力较低,脲酶受抑制明显,抑制率分别高达30.35%和28.89%;NPK+秸秆和NPK+有机肥土壤的脲酶活力高,脲酶抑制率低,最高抑制率分别为21.35%和16.86%,不同肥力土壤在整个处理过程中,脲酶抑制率均为先逐渐增大到最大值,然后又逐渐降低;高肥力土壤脲酶抑制率最大值出现的时间比低肥力土壤迟,表明高肥力土壤对阿特拉津有较强的耐受能力。 相似文献
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干旱区绿洲-荒漠过渡带灌丛土壤属性研究 总被引:16,自引:1,他引:15
以天山北坡绿洲 荒漠过渡带为研究区,选择3种类型的灌丛并采集不同位置和深度的灌丛土壤样品进行分析,研究灌丛土壤资源的聚集效应.结果表明,干旱区绿洲 荒漠过渡带不同类型灌丛对土壤粒度分布的影响不显著,土壤以砂和粉砂为主,红柳+裸地灌丛土壤粒度分布的聚集效应明显;灌丛土壤有机质、全氮和速效钾含量在冠幅下最高,其次为灌丛间低矮植物下,灌丛间裸地最低,呈现出明显的“肥岛”现象;不同灌丛类型和采样位置对土壤盐分离子和总盐含量的变化影响显著,且不同灌丛土壤资源的聚集效应各异;导致不同类型灌丛土壤资源富集率不同的原因有气候因素、灌木分布的土壤环境、灌丛高度和冠幅、灌丛间有无低矮植物等. 相似文献
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K. M. Perroux 《Plant and Soil》1979,52(3):385-392
Summary A simple method of control for soil water potential in subirrigated pots is presented. The system is tested in a glasshouse trial. No uncontrolled excursions in soil water potential were observed, and the soil water tension was held constant to less than ±15%. Reasons for fluctuations in potentials and recommendations for their reduction are made. 相似文献
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Hiroshi Takeda 《Population Ecology》1973,15(2):76-89
- A study was made of the populations of Collembola in the pine forest. Among the eight species commonly found, Folsomia octoculataHandschin was numerically dominant.
- Seasonal population changes of these eight species were described over a year. It was found that many species show two peaks in number. As for F. octoculata, the dominant species, the changes in number was discussed in connection with the variation in age structure.
- The census data for each species were examined for the distribution pattern by using the regression method. None of these eight species was distributed at random in the soil and they could be classified into three groups based on the differences in the degree of aggregation in terms of coefficient β of the regression. It was suggested that such differences in the distribution pattern are largely due to differences in the response to heterogeneity of the habitat. In the case of F. octoculata, the changes of distribution pattern in the course of post-embryonic development were examined and it was found that (a) the component of distribution is a single individual rather than a colony, and (b) the degree of aggregation is decreased with the development of individuals.
- Using the relationship, the relation of the necessary sample size to the population density was derived for a fixed level of presision (D=S.E./m=0.2) and some suggestions were given concerning sampling plans for these insects.
19.
鹤山不同植被类型土壤惰性碳含量及其季节变化特征 总被引:1,自引:0,他引:1
为探讨植被恢复下森林土壤惰性碳(Non-labile carbon, NLC)的分布和季节动态,对鹤山6种不同植被类型(灌草、马尾松、桉树、乡土树种、马占相思、季风常绿阔叶林)不同土层(0~10 cm、10~20 cm和20~40 cm)NLC进行研究。结果表明: 6种植被类型土壤NLC含量均以表层(0~10 cm)最高,且随土层深度增加有下降趋势。表层土壤NLC含量受植被类型的影响显著,马占相思林的土壤NLC含量显著高于其他林型;马尾松林的土壤NLC含量最低,与其他林型差异显著。马占相思林深层土壤(10~20 cm和20~40 cm)的NLC含量显著高于其它植被类型,其它植被类型间无显著差异。不同植被类型的土壤NLC含量具有不同的干湿季动态变化,湿季土壤NLC占土壤总有机碳(Soil organic carbon, SOC)的比值高于干季。从不同土层NLC占SOC的比例可见,马占相思林和灌草林能显著提高土壤不同层次的NLC含量,马尾松林、桉树林、乡土树林和季风常绿阔叶林则有利于提高深层土壤SOC稳定性。 相似文献
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不同利用方式土地秋季大型土壤动物群落结构 总被引:38,自引:0,他引:38
为了解不同利用方式土地的大型土壤动物群落结构,于2004年10-11月对浙江省金华市市区北部7种土地,即农田(P)、菜园(K)、果园(O)、荒地(W)、庭院(Y)、草皮绿地(L)和建筑工地(B)进行垂直(上、中、下3层)取样,共获得大型土壤动物1 161只,隶属3门8纲20目.分析表明大型土壤动物群落优势类群为近孔寡毛目、膜翅目,常见类群为蜘蛛目、双尾目、正蚓目、等足目、柄眼目、鞘翅目、鳞翅目和双翅目,其他均为稀有类群.大型土壤动物群落的群落复杂性指数(C)为O>K>W>B>L>P>Y,Shannon-Weiner指数(H′)为L>B>W>K>O>P>Y,C比H′更好体现了群落的复杂性与多样性.垂直分布显示大型土壤动物具明显的表聚现象.根据大型土壤动物群落聚类和排序的结果,可将7种土地分为3组,即强干扰无植被组、草本种植组和果园组,显示了大型土壤动物对不同土地利用方式的响应情况. 相似文献