Spatial-temporal variation in soil respiration and its controlling factors in three steppes of Stipa L. in Inner Mongolia, China

Grassland is the largest terrestrial ecosystem in China. It is of great significance to measure accurately the soil respiration of different grassland types for the contribution evaluation of the Chinese terrestrial ecosystem’s carbon emission to the atmospheric CO2 concentration. A three-year (2005-2007) field experiment was carried out on three steppes of Stipa L. in the Xilin River Basin, Inner Mongolia, China, using a static opaque chamber technique. The seasonal and interannual variations of soil respiration rates were analyzed, and the annual total soil respiration of the three steppes was estimated. The numerical models between soil respiration and water-heat factors were established respectively. Similar seasonal dynamic and high annual and interannual variations of soil respiration were found in all of the three steppes. In the growing season, the fluctuation of soil respiration was particularly evident. The coefficients of variation (CVs) for soil respiration in different growing seasons ranged from 54% to 93%, and the annual CVs were all above 115%. The interannual CV of soil respiration progressively decreased in the order of Stipa grandis (S. grandis) steppe 】 Stipa baicalensis (S. baicalensis) steppe 】 Stipa krylovii (S. krylovii) steppe. The annual total soil respiration for the S. baicalensis steppe was 223.62?299.24 gC m-2 a-1, 150.62-226.99 gC m-2 a-1 for the S. grandis steppe, and 111.31–131.55 gC m-2 a-1 for the S. krylovii steppe, which were consistent with the precipitation gradient. The variation in the best fitting temperature factor explained the 63.5%, 73.0%, and 73.2% change in soil respiration in the three steppes at an annual time scale, and the corresponding Q10 values were 2.16, 2.98, and 2.40, respectively. Moreover, the Q10 values that were calculated by soil temperature at different depths all expressed a 10 cm 】 5 cm 】 surface in the three sampling sites. In the growing season, the soil respiration rates were related mostly to the surface soil moisture, and the 95.2%, 97.4%, and 93.2% variations in soil respiration in the three steppes were explained by the change in soil moisture at a depth of 0-10 cm, respectively.

Evaluation of Characteristics Floristico-Edaphic of the Steppes at Alfa (<i>Stipa tenacissima</i>L.) in the Saida Region (Western Algeria)

To establish an assessment of floristic and edaphic characteristics of steppe formations we conducted a phytoecological study on a local scale by comparing the current plant diversity and soil in three (3) stations representative of the vegetation to alfa (Stipa tenacissima L.) located south of Saida (western Algeria). The relations between the station, the vegetation and the characteristics of soils in the steppe are very imperfectly known. This study intends to analyze the relationship between floristic composition and edaphic parameters of the steppe at alfa. Anthropogenic pressures on plant structure are different imbalance resulting in one ecological. The floristic and edaphic data have been the subject of a factorial correspondence analysis (A.F.C). The floristic inventory denotes a regressive dynamics of the formations at alfa passing from one site to another. Thus 39 plant species have been inventoried in the site in good condition, against 26 species for the moderately degraded site and 16 species only for the damaged site. The coupled results between species and edaphic parameters show the relations between the plant diversity and the physico-chemical characteristics of the soils. The statistical analyses do appear a strong correlation between floristic composition, the state of vegetation and the edaphic parameters.

内蒙古草原针茅属六种植物的花粉形态研究

作者对内蒙古天然草原六种针茅属植物的花粉粒进行扫描电子显微镜观察，发现在花粉粒大小、萌发孔直径、颗粒状纹饰的粗细及孔环特征等性状方面均有显著差异。

内蒙古中西部草原区五种针茅的遗传多样性研究

利用RAPD(Random Amplified Polymorphism DNA,RAPD)分子标记技术,对内蒙古中西部草原区16个不同地理种群的五种针茅的遗传多样性及其种间关系进行了研究。从102个10碱基随机引物中筛选出28个有效引物,共扩增出389条带,多态性条带345条,占88.69%,说明针茅属植物具有丰富的遗传多样性,对环境的适应能力较强,PCA分析表明水热成为其地理分布的决定性因素。依据五种针茅的Jaccard相似系数所做的UPGMA聚类分析表明,大针茅和克氏针茅之间的遗传距离比较小聚为一类,它们与本氏针茅、短花针茅和小针茅间的遗传距离都比较大。

中国针茅属植物的地理分布

本文论述了中国针茅属植物的地理分布、生态特点及其与植被分布的关系。中国针茅属有32种1亚种及4变种,据该属各个种所处环境中的气候和土壤等因素的变化,不同种的分布也各异。属的分布区的类型属于吴征镒(1979)的中国植物区系分区的泛北极植物区中的6个植物亚区,即亚洲荒漠植物亚区,欧、亚森林植物亚区,青藏高原植物亚区,中国-喜马拉雅植物亚区,欧、亚草原植物亚区及中国-日本森林植物亚区。

紫花苜蓿和短花针茅根系分布与土壤水分研究

以陕北农牧交错带人工草种紫花苜蓿(Medicago sativa L.)和天然草种短花针茅(Stipa breviflora Griseb.)为对象,采用根钻法调查两个草种的根系垂直分布以及刈割后苜蓿根系变化特征,并通过定位观测研究土壤水分动态变化。结果表明:紫花苜蓿和短花针茅根系密度随土壤深度增加而减少,而且均以直径小于等于1 mm的须根为主;0~50 cm土层紫花苜蓿和短花针茅根系量分别占0~100 cm剖面总量的67%和84%。紫花苜蓿和短花针茅根系分布与土壤水分消耗特征吻合。生长旺盛期苜蓿大量消耗0~140 cm土层土壤水分,5-9月平均有效土壤储水不足10 mm;生长季末深层(140~280 cm)土壤储水也逐渐降低,约为裸地储水量的50%。短花针茅0~280cm剖面土壤水分状况明显好于苜蓿地,比苜蓿地多储水100 mm左右;主要消耗浅层(0~50 cm)土壤水分,深层水分利用较少。

针茅属植物基因组DNA提取方法的研究

植物体内所含的蛋白质、酚类、单宁、色素及多糖等物质影响Tag酶的聚合效率,是使PCR扩增反应失败的主要因素。本研究以针茅属植物为材料,对CTAB法、SDS法、简易提取法和高盐沉淀法提取的针茅DNA进行了比较研究,结果表明:CTAB法适合于针茅属植物基因组DNA的提取,采用这种方法提取的DNA能很好的用于PCR扩增。

内蒙古草原三个优势针茅种群的自交繁殖能力研究

传粉方式是植物生态适应性的重要表现,通过对内蒙古典型草原优势种大针茅(Stipa grandis)、克氏针茅(Stipa krylovii)和草甸草原优势种贝加尔针茅(Sitpa baicalensis)花果期套袋处理,测定了其自交繁殖能力.三种针茅套袋处理都产生了相当数量的有效结实,且种子均能很好萌发,其中大针茅和克氏针茅套袋处理千粒重和萌发力总体优于自然条件未套袋的对照处理,贝加尔针茅略低于对照处理.结果表明:三种针茅均自交亲和,并有很强的自交能力,其中大针茅和克氏针茅的自交能力较高,贝加尔针茅的相对较低.

青海针茅属植物的调查研究初报

调查和研究了青海针茅属植物,初步确定有16种和4变种,并记载了每个种在我省的产地、生境和地理分布.

内蒙古几种针茅特性和生态地理分布的研究

本文对内蒙古几种针茅的特性和分布的分析．指出内蒙古针茅属的分布集中在草原区内，分布最广是石生针茅，其次是克氏针茅。针茅属有性繁殖微弱，成熟种子量不多，入土困难，损伤量大．幼苗死亡率高，特别在退化地段更加突出；无性繁殖为主．分蘖芽集中在果后营养期产生，春季拔节期是少量的．当年枝条不形成分蘖；春季以细根产生为主．拔节期为不定根产生的时期．孕穗和开花期根系向横深伸展；群落生物量为单峰曲线。地上生物量为“金字塔”型，地下生物量是“倒金子塔”型。草地利用过度．草群低矮，根系集中于土壤表层。

黄土高原北部草地土壤水分空间变异研究

土壤水是维系黄土高原恢复生态系统稳定性和可持续性的关键因子。为深入理解黄土高原不同类型草地恢复生态系统土壤水的分布特征,采用经典统计学与地统计学方法,分析了陕北神木六道沟小流域样地尺度长芒草和苜蓿草地0~500 cm剖面土壤水分的空间变异特征。结果表明:两种草地土壤水分随土层深度增加均呈先增大、后减小,而后趋于稳定的变化趋势,具有中等程度变异性。垂直方向上两种草地土壤含水量及空间变异系数均具有显著差异(P<0.001),苜蓿和长芒草地0~500 cm剖面土壤水分变异系数平均值分别为0.19和0.33。总体上,苜蓿导致深层土壤水过度消耗,70cm以下土层土壤含水量明显低于长芒草地,其高耗水特性削弱了垂直方向140 cm以下土层土壤水的空间变异强度。因此,苜蓿植被强化了土壤水在垂直方向上的循环,并导致深层土壤水负平衡,进而使样地尺度土壤水在水平方向的分布趋于均质化。