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1.
割草干扰对典型草原土壤咎子库种子数量与组成的影响   总被引:8,自引:0,他引:8  
对具有生命力的种子数量及其垂直分布进行了研究,结果表明:刈割对土壤种子库中的种子数量有一定的影响,其中对照具有生命力的种子数量,1997年和1998年分别为2415和2253粒/0.12m^3,割一年休一年的处理分别为对照的93.13%和78.38.5,一年割一次的处理分别为对照的83.23%和58.50%,从以上 数值可见同一处理内部种子的数量亦有下降,不同处理种子数量的垂直分布有共同趋势,有7  相似文献   

2.
对种子雨的来源及其降落进行了研究,结果表明:种子雨的来源取决于各种植物结实的种子数量.60 种植物单株结实的种子数量有很大差异,禾草种子数量相对较少,杂类草较多,一、二年生植物的种子数量亦多.种子雨的降落,是通过独立、风力、附着、动物和原地等散布形式来实现的.单位面积上种子的数量取决于群落的种类组成和有结实能力的植株.通过实测和模拟,单位面积上可能降落的种子数量相差不大,前者为16763 粒·m - 2 ,后者为18536 粒·m - 2 .不同刈割处理,可能降落的种子数量不同,一年割一次的平均为8525±9246 粒·m - 2 ,割一年休一年的为5936±2835 粒·m - 2 和对照为6593±4654 粒·m - 2 .各处理内的不同样方亦有很大的差异  相似文献   

3.
金平  张著林 《贵州科学》1998,16(3):212-215
用植物激素对贵州特有,稀有植物-青岩油杉种子进行预处理试验,结果表明,以400μg/L的IBA溶液处理种子,出苗率达52.5%比对照高19.5%;用400μg/L的NAA溶液处理种子,一年生苗高12.3cm,地径粗0.19cm,比对照增高4.5cm,增粗0.04cm,2,4-D溶液也可在不同程度上提高种子出苗率及苗木年生长量。  相似文献   

4.
对内蒙古库布齐沙带东段油蒿(Artemisiaordosica)固定沙兵土壤微生物数量的垂直分布进行了研究.1)好气性细菌和真菌数量的垂直分布是结皮层(0-0.5cm)〉0.5-10cm〉30-40cm〉60-70cm,在0-10cm,油蒿固定沙丘与流动沙丘比值;好气性细菌数量为13.7:1,真菌数量为15.2:1;2)芽孢细菌和放线菌数量的垂直分布是0.5-10cm〉30-40cm〉结皮层(0-  相似文献   

5.
对典型草原群落生物量的组成与种子数量的组成进行了比较研究,主要结果如下;在割草干扰下,割一年休一年和一年割一次的群落生物量分别较对照下降了15.58%和25.31%;具有生命力的种子数量分别较对照下降11.35%和27.33%。种群相对生物量与相对种子数量没有一致的关系,表现为5种形式,即生物量较高而种子数量较低;生物量较低而种子数量较高;生物量与种子数量相近;在生物量而无种子数量和无生物量而有种子数量。不同科植物生物量与种子数量有一定的差异。禾本植物生物量较高,而种子数量较低;菊科植物生物量较低,而种子数量较高,豆科植物生物量一般高于种子数量;其余科植物均有各自的特点。不同生活型植物生物量与种子数量也有差异。多年生草本植物生物量最高,而种子数量较低;一年生、二年生草本植物生物量较低,而种子数量占总量的一半以上;灌木和小半灌生物量和种子数量均较低。  相似文献   

6.
库布齐固定沙丘土壤微生物数量与土壤生态因子的研究   总被引:24,自引:1,他引:24  
研究内蒙古库布齐沙带东段固定沙丘土壤微生物数量变化与土壤生态因子的关系,结果表明,土壤微生物总数量的季节变化与土壤养分含量的季节变化基本一致,均为春季和秋季〉夏季;从流动沙丘到固定沙丘,植物种类组成,土壤微生物数量和土壤养分含量,均出现相同的变化规律,由少逐渐增多;库布齐固定沙丘的土壤微生物土层垂直分布规律有其地域的独特性,在0.5~10cm和150~160cm土层中,无芽孢细菌,芽孢细菌和放线菌  相似文献   

7.
江苏泥质海岸防护林土壤微生物数量分布及其类群的研究   总被引:1,自引:0,他引:1  
凡营造防护林的林地,其土壤微生物的总量平均比对照滩涂高出100余倍,比农田高出20余倍,其中刺槐林、竹林土壤微生物总量明显高于水杉林;微生物类群以细菌为主体,放线菌为次,真菌最少(细菌在每克干土中约900 ̄8000万,放线菌为200 ̄2400万,真菌为0.8 ̄1.7万);土壤微生物数量的垂直分布随着土层深度而递减,以0 ̄20cm范围内居多;土壤微生物的数量春季略大于秋季。  相似文献   

8.
在不同轮割处理中,群落干、鲜比值实有年平均值如下:一年割两次为0.4077±0.0428、一年割一次为0.3947±0.0572、割一年休一年为0.4219±0.0545、割二年休一年为0.4157±0.0613和对照为0.4728±0.0531.在同期刈割的处理中,其比值有随割草次数增加而减少的趋势.种群干、鲜比值的变化有各自的特点,一般在同期刈割处理中,随着割草次数增多而下降;一年割两次和对照较高;相互之间没有明显趋势.依割一年休一年排列的顺序中,Stipagrandis最高(0.5294±0.0366)、Orostachysmalacophyllus最低(0.1259±0.0571),其余种群介于两者之间.对群落和种群干、鲜比值的影响因素与前文类似.  相似文献   

9.
高压静电场对蟆叶秋海棠愈伤组织生长的效应   总被引:3,自引:0,他引:3  
用+ 1.0 kV/cm 场强高压静电处理蟆叶秋海棠愈伤组织30 m in, 处理组愈伤组织生长速率达90.7m g/d,比对照组高23% ,超氧物歧化酶(SOD)活性、蛋白质及可溶性糖含量分别为179.0 u/g·FW、14.4 m g/g·FW、49.0 m g/g·DW, 分别比对照增加10.6% 、10.8% 、7.7% 。过氧化物酶 (POD) 和吲哚乙酸(IAA) 氧化酶活性分别为58.0 O.D470/m in·g FW, 163.8 μg/g·h FW, 分别比对照下降12.7% 和23.3% 。  相似文献   

10.
为了探索芦笋育苗和高产技术,于1999年9月中旬在柳州市太阳村镇上等村进行芦笋育苗试验,品种为美国芦笋UC157和UC72,试验面积为0.667hm^2。种子播种前经过晒种、漂洗、消毒、浸种催芽处理。播种行距13cm~15cm,株距7cm~8cm,种子播后覆细土1cm~2cm。结果是UC157品种平均出苗率82.3%,平均成苗率64.86%,每颗种苗长出地上茎平均有3.3条,最多6条,幼苗平均高1  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

14.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

17.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

18.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

19.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

20.
1 Rise of studies on climate change's effects on biodiversity
Until the 1980s, climate change and biodiversity were studied as two independent disciplines for more than a century. In 1992, the Ecological Society of America's annual report named climate change, biodiversity, and the sustainable ecological system as the three major global environmental issues of the twenty-first century [1].  相似文献   

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