湿地植物对外源氮、磷输入的响应研究

通过人工控制试验,研究了氮、磷输入对沼泽湿地植物地上生物量,相对密度以及植物对氮、磷吸收量的影响.结果表明:营养物质氮、磷的长时间累积,导致湿地植物地上生物量和相对密度均呈逐渐下降的年际变化趋势,地上生物量和相对密度之间表现为微弱的单峰变化关系.在氮输入下,随着氮施用量的升高,氮的吸收率从62.3%下降到5.5%;在磷输入下,随着磷施用量的升高,磷的吸收率从3.1%下降到0.8%.氮、磷的施用量愈高,植物对氮、磷的吸收率愈小.氮、磷输入有可能改变湿地生态系统的物种组成和结构及湿地生态系统的稳定和保护,应当考虑湿地中营养物质的长期作用.      

三江平原毛果苔草湿地物理过程——能量环境的基本特征

从整个生长季(1999-04-30～09-30)来分析,到达毛果苔草湿地生态系统的太阳辐射能总量约为2673.06MJ/m2.太阳总辐射在一天内不同时间段累积呈现出单峰型曲线(抛物线型);分光辐射总量呈明显的单峰曲线(抛物线型),在分光辐射的几个分量中,光合有效辐射的分配比总是最大,其次是红外辐射,最小的是紫外辐射.净辐射主要与下垫面的季节性植被季相有关,生长初期与生长末期较大,而生长旺盛期较小.      

落新妇地下部分挥发油化学成分GC-MS分析

利用水蒸汽蒸馏法提取落新妇地下部分的挥发油,测得含量为0.10%;采用气相色谱-质谱联用技术(GC-MS)对落新妇的挥发性成分进行了分离鉴定,分离出57种成分,鉴定了其中50种;运用峰面积归一法确定了各成分的相对含量,检出率为87.71%.落新妇地下部分挥发油的主要成分为邻苯二甲酸二丁酯、十六甲基八环硅氧烷.     

Even low to medium nitrogen deposition impacts vegetation of dry, coastal dunes around the Baltic Sea

Coastal dunes around the Baltic Sea have received small amounts of atmospheric nitrogen and are rather pristine ecosystems in this respect. In 19 investigated dune sites the atmospheric wet nitrogen deposition is 3-8 kg N ha⁻¹ yr⁻¹. The nitrogen content of Cladonia portentosa appeared to be a suitable biomonitor of these low to medium deposition levels. Comparison with EMEP-deposition data showed that Cladonia reflects the deposition history of the last 3-6 years. With increasing nitrogen load, we observed a shift from lichen-rich short grass vegetation towards species-poor vegetation dominated by the tall graminoid Carex arenaria. Plant species richness per field site, however, does not decrease directly with these low to medium N deposition loads, but with change in vegetation composition. Critical loads for acidic, dry coastal dunes might be lower than previously thought, in the range of 4-6 kg N ha⁻¹ yr⁻¹ wet deposition.     

Iron-rich dune grasslands: Relations between soil organic matter and sorption of Fe and P

Effects of high atmospheric nitrogen-deposition partly depend on availability of phosphate. Lime-poor, but iron-rich dune grasslands are supposedly protected from grass-encroachment, due to P-fixation in iron phosphate. However, in iron-rich Dutch hinterdunes, dunes have low, but dry former beach plains high grass-encroachment. To test whether these zones differ in nutrient availability, and whether this changed with duration of grass-encroachment, we measured net N-mineralization, microbial characteristics and different fractions of P and Fe from pioneer and shortgrass to tallgrass stages approximately 10, 20 and >25 years old. N-mineralization did not differ between zones, but increased in older tallgrass stages in the organic layer. P-availability was significantly lower in the low grass-encroachment zone, with SOM values below 3% and mineral Fe above 40% allowing for P-fixation in iron phosphates. In the high grass-encroachment zone, however, P-availability increased, because SOM increased and Fe became incorporated in organic matter complexes, with more reversible P-sorption.     

Grazing effects on sustainable semiarid rangeiands in Patagonia: The state and dynamics of the soil seed bank

The composition of the germinable seed bank was studied in four vegetation states of the Festuca pallescens grasslands in semiarid Patagonia during four years. The aim of this study was to test whether above-ground vegetation states resulting from grazing exclusion or different combinations of grazing and topography are reflected in different states of the germinable seed bank. The size of the total and dicot germinable seed bank was positively related to the total cover in each state. Dicots dominated all germinable seed bank states. Carex patagonica increased its cover as well as its germinable seed bank under grazing disturbance. Grazing did not reduce the germinable seed bank of perennial grasses in uplands where the grazing pressure is lower as compared with slopes. In slopes the germinable seed bank of perennial grasses was significantly reduced by grazing. A reduction of the length of the grazing period in late spring increases the germinable seed bank of perennial grasses both in upland and slope. These results are interpreted in the frame of a model of management techniques where grazing exclusion during late spring and late summer increases the seed bank of the perennial grasses and promotes their establishment in uplands. The artificial addition of seeds of perennial grasses and the manipulation of the soil surface in order to increase "safe sites" appear as management alternatives that deserve further evaluation to improve plant reestablishment in slopes.     

三江平原露水资源研究

研究了三江平原露日的变化特征,并对沼泽地毛果苔草(Carexlasiocarpa)群落和大豆地中露水的凝结进行了实地观测。结果表明:三江平原露水出现频率较高的季节是夏秋季(6～9月),露水凝结量最多的月份是9月;近12年来,年露日在66～108d,平均为95.42d;7～9月大豆地地面的露水凝结量明显高于沼泽地地面,而5～6、10月低于沼泽地地面;沼泽地中冠层的露水凝结量最多,地面上的露水量略低于顶层,而大豆地中露水凝结量的垂直差异不明显;2003年沼泽地、大豆地单位土地面积上实际凝结的露水量为20.68、19.46mm,分别占同期降雨量的5.05%、4.75%。露水在一定程度上弥补了干季降雨的不足,是影响水量平衡的重要因子。     

长白山区沟谷乌拉苔草(Carex. meyeriana)沼泽湿地水文物理效应

通过对长白山区沟谷乌拉苔草(C.meyeriana)沼泽湿地和三江平原乌拉苔草沼泽湿地土壤物理性质和乌拉苔草根系生物量的测定,对水文物理效应进行了分析,结果表明:长白山区沟谷乌拉苔草沼泽湿地的土壤孔隙度小于三江平原乌拉苔草沼泽湿地,容重和体积质量则高于三江平原乌拉苔草沼泽湿地。土壤蓄水能力低于三江平原乌拉苔草沼泽湿地;乌拉苔草发达的根系具有强大的蓄水能力,尤以根鞘的蓄水能力最强,蓄水可以占鲜质量的91.1%~93.72%,比根系蓄水能力高出2.54%~33.94%。由此得知乌拉苔草沼泽湿地的具有巨大的蓄水能力,是天然的水调节器。通过分析可知其水文物理过程对沼泽湿地对其上游河流具有调节作用,同时还可以保存上游河流生物多样性,以及严重的影响着水面以下化学过程的发生。     

The differentially-expressed proteome in Zn/Cd hyperaccumulator Arabis paniculata Franch. in response to Zn and Cd

The Zn/Cd hyperaccumulator Arabis paniculata is able to tolerate high level of Zn and Cd. To clarify the molecular basis of Zn and Cd tolerance, proteomic approaches were applied to identify proteins involved in Zn and Cd stress response in A. paniculata. Plants were exposed to both low and high Zn or Cd levels for 10 d. Proteins of leaves in each treatment were separated by 2-DE (two-dimensional electrophoresis). Nineteen differentially-expressed proteins upon Zn treatments and 18 proteins upon Cd treatments were observed. Seventeen out of 19 of Zn-responsive proteins and 16 out of 18 of Cd-responsive proteins were identified using MALDI-TOF/TOF-MS (matrix-assisted laser desorption/ionization time of flight mass spectrometry). The most of identified proteins were known to function in energy metabolism, xenobiotic/antioxidant defense, cellular metabolism, protein metabolism, suggesting the responses of A. paniculata to Zn and Cd share similar pathway to certain extend. However, the different metal defense was also revealed between Zn and Cd treatment in A. paniculata. These results indicated that A. paniculata against to Zn stress mainly by enhancement of energy metabolism including auxin biosynthesis and protein metabolism to maintain plant growth and correct misfolded proteins. In the case of Cd, plants adopted antioxidative/xenobiotic defense and cellular metabolism to keep cellular redox homeostasis and metal-transportation under Cd stress.     

滇白前(Silene viscidula)对铅、锌、镉的共超富集特征

为了寻找新的重金属超富集植物特别是多金属共超富集植物,调查测定了云南兰坪铅锌矿区北厂矿段生长的8种植物及其根区土壤的重金属质量分数,以及土壤基本理化性质.结果表明:研究区土壤中磷和钾质量分数较低,总氮、总磷、总钾、铵态氮、硝态氮、速效磷分别占土壤干质量的0.2%、0.03%、0.52%、0.0029%、0.000 12%、0.00068%;有机质质量分数平均为4.81%,pH值平均为6.79,电导率变化范围为11.4～140-3μs·cm-1.该矿区土壤中锌(Zn)、铅(Pb)、镉(Cd)、铜(Cu)的质量分数平均值分别为(38 178±23 870)、(18 671±10 143)、(438±345)、(159±:82)mg·kg>-1,除Cu外均超过国家土壤环境质量(GB 15618-1995)三级标准.8种植物地上部Zn、Pb、Cd、Cu质量分数范围分别为271～17 986、51～5 430、1～617、2～26mg·kg-1,尤以滇白前(Silene viscidula Franch)地上部Zn、Pb、Cd质量分数为最高.进一步采集38个滇白前样本对其重金属富集特征进行深人调查,表明其地上部中含zn、Pb和Cd平均为(11 043±3 537)、(1 546±1 044)和(391±196)mg·kg-1,富集系数(地上部和土壤金属质量分数之比)分别为0.35、0.08和1.05,转运系数(地上部和根中金属质量分数之比)均超过1,均值分别为8.21、3.90和8.36.野外调查数据表明,滇白前是一种Pb/Zn/Cd共超富集植物.滇白前对Zn、Pb富集系数小于1,主要是由于其对应土壤中Zn、Pb质量分数太高(平均分别为(45 778±32 819)、(22 512±13 613)mg·kg-1)所致.