异质生境水位差异对小叶章有性繁殖分配的影响

以三江平原湿地代表植物小叶章为对象,通过对杂类草草甸、典型草甸、沼泽化草甸、沼泽生境中小叶章个体大小与生物量差异及繁殖构件与植株生物量之间相关关系的分析,研究不同生境中水位对小叶章个体生物量与繁殖分配的影响。结果表明: 小叶章个体大小、高度及有性繁殖特征随水位升高而显著降低;杂类草草甸、典型草甸、沼泽化草甸和沼泽中小叶章的繁殖阈值分别为0.245、0.149、0.148和0.157 g;除沼泽化草甸外,其他3种生境中小叶章植株个体大小与繁殖分配均呈显著负相关;相较于个体大小,土壤含水量对于小叶章有性繁殖分配影响更大,不同生境中小叶章对个体大小和繁殖分配的差异投资是其具有良好生态适应性的基础条件。     

包膜尿素在华北平原夏玉米上的应用

通过连续2a的大田试验,比较研究了尿素与包膜尿素对夏播玉米郑单958和农大108产量、水分利用效率（WUE）、氮肥利用率（NUE）与土壤无机氮动态的影响,结果表明：产量与WUE随施氮量增大而增大,两种氮肥间差异不显著;包膜尿素NUE较尿素高,2004年郑单958N90kg／hm^2与农大108N180ks／hm^2条件下提高显著;施氮对土壤无机氮动态的影响具有年际间差异：2004年不施氮条件下一般呈“V”型变化趋势,施氮使其向“N”型或倒“V”型转变,而2005年施氮与不施氮条件下均呈“N”型变化趋势;施氮使土壤无机氮含量明显提高,包膜尿素较尿素效果更明显;土壤无机氮含量,包膜尿素处理以表土层最高,而尿素处理,特别是尿素N180kg／hm^2处理9叶展至吐丝期以下层土壤较高,2004年表现尤为明显。可见在降水量较多的年份,包膜尿素缓释效应明显,能有效控制无机氮的下移。华北平原夏玉米季以包膜尿素替代尿素、以一次性基施替代基肥＋追肥是完全可行的,能达到省工、增效、环保目的。     

三江平原典型湿地土壤剖面有机碳及全氮分布与积累特征

研究了三江平原2类典型湿地(毛果苔草沼泽和芦苇沼泽)沉积物剖面有机碳、全氮的分布特征与积累现状.结果表明,2类沼泽剖面有机碳分布均具有明显的储碳层和淀积层;上层的储碳层厚度约为60 cm,有机碳平均含量分别为96和184 g·kg^-1,全氮平均含量分别为7.4和17.6 g·kg^-1;下层的淀积层内有机碳和全氮含量低而稳定.2类沼泽剖面有机碳和全氮含量随剖面深度增加而下降, 有机碳、全氮与容重之间相关均极显著(P＜0.01).2类典型湿地有机碳密度在20～40 cm剖面内最大.储碳层内,有机碳储量分别为1.83×10⁴和1.73×10⁴ t·km^-2,全氮储量分别为1.45×10³和1.67×10³ t·km^-2;100 cm以内,有机碳储量分别为2.86×10⁴和262×10⁴ t·km^-2,全氮储量分别为2.18×10³和2.49×10³ t·km^-2.植被类型对湿地剖面有机碳、全氮含量及储量均具有不同程度的影响.     

Decomposition and litter production in a northern bald cypress swamp

Abstract. Primary production as measured by annual mean litter fall in the Lower Cache near Perks, Illinois, was the lowest recorded for cypress swamps (2345.5 kg/ha/yr). This swamp is continuously flooded with a low input of phosphorus (< 0.24 mg 1). Rates of leaf litter decomposition were higher in the Lower Cache for Taxodium distichum than in swamps to the south of the region. The winter rates of leaf litter decomposition in the Lower Cache were slower than summer rates for Cephalanthus occidentalis, Echinochloa muricata, Polygonum pensylvanicum, Jussisaea repens, Taxodium distichum, and Eleocharis obtusa, but not for Typha latifolia. Because the 99% turnover rates for these species (0.69–5.10 years) often exceeds one year, undecomposed litter can be expected to accumulate or be exported from the system. Most leaves are shed in the autumn (October through December; 83.6%).     

Early-stage litter decomposition and its influencing factors in the wetland of the Sanjiang Plain, China

Using the litter bag technique, the decomposition rates and their influencing factors were studied by investigating three wetland macrophytes, Calamagrostics angustifolia, Carex meyeriana and Carex lasiocapa, in Sanjiang Plain, Northeast China. It was revealed that C. lasiocapa lost 28.91% of its weight, C. angustifolia lost 31.98% and C. meyeriana lost 32.99% after 164 days. Another finding was that the amount of organic carbon in the litter of C. angustifolia and C. lasiocapa fluctuated, but continuously decreased in that of C. meyeriana. However, all the three types of litter released organic carbon. Nitrogen was released substantially from the litter of both C. angustifolia and C. meyeriana, but accumulated in the litter of C. lasiocapa. Phosphorus concentrations in all the three types of litter apparently decreased first and then slightly increased. Overall, P release was observed in all the three types of litter. The C/N and C/P ratios varied significantly in the decomposition process. The decomposition rates and nutrient content variations were simultaneously influenced by the quality of the litter as well as the environmental factors in the Sanjian Plain, but they were more strongly affected by the quality of the litter.     

基于GIS的下辽河平原地下水生态敏感性评价

从地下水系统结构特征、区域自然条件、外界压力、资源与保护和生态环境5个方面考虑,构建了下辽河平原地下水生态敏感性评价指标体系.运用GIS空间分析技术,从水量和水质两方面对下辽河平原地下水生态敏感性进行评价.结果表明:在水量敏感性方面,主要以轻度与中度敏感区为主,占研究区总面积的65.14％;在水质敏感性方面,主要以轻度和中度敏感区为主,占研究区总面积的86.56％.综合水量和水质两方面,下辽河平原地下水生态敏感性在中度敏感以上的区域面积占研究区面积的59.62％,生态敏感性较高,容易受到破坏.从空间分布来看,不敏感和轻度敏感区分布在新民一辽中平原、东部山前冲洪积平原;中度敏感区域主要分布在中部平原及西部低山地区;高度敏感和极敏感区分布在辽阳和抚顺城区、平原周围山区.     

不同生长阶段毛苔草（Carex lasiocarpa）克隆繁殖对水文情势的响应

毛苔草为三江平原沼泽湿地分布区典型沼生植物.通过幼苗移植水位控制试验,研究不同生长期毛苔草克隆繁殖对水文情势的响应.结果表明,干湿交替条件下,毛苔草分蘖能力最强;苗期处理对后期分蘖有显著影响,后期水分增多明显促进分蘖,但不同经历的毛苔草分蘖对水分条件改变的响应速度不同.-5cm水位条件下,毛苔草根茎长度最大,而持续淹水15cm条件下,毛苔草根茎后期伸展最快.稳定水文条件的改变,抑制根茎生长,从波动水文情势转到稳定的水文环境中,根茎生长得到促进.-5cm水位条件下,毛苔草根茎生物量占总生物量的比重最大;而且水文情势改变后,无论苗期还是生长季末期,仍以经历-5cm水位处理的毛苔草根茎生物量比重较大.淹没对毛苔草的克隆繁殖具有明显的抑制作用.为实现湿地植被重建的目标,应综合考虑植物在不同环境中繁殖策略的差别,以及不同阶段水文需求的差别.     

Lichen biota of West Siberia

The author has surveyed the diversity of lichen biota of West Siberia and distribution of lichens over its two geographic parts: the West Siberian Plain and the mountain frame in the south of West Siberia. The diversity of lichen biota in entire West Siberia is currently estimated at 1845 species in 325 genera and 95 families. The diversity of the West Siberian Plain is estimated at 1421 species in 271 genera and 86 families, and that of the southern mountains of West Siberia, at 1682 species in 312 genera and 94 families.