Specific Features of the Population Ecology of Creeping Thistle, Cirsium arvense(L.) Scop. s. l.

Two populations of creeping thistle (Cirsium arvense) growing in a field uncultivated for many years and on the sloping bank of an artificial pond were studied with respect to the demographic and chemical composition. The results showed that the contents of some elements in plants depend on specific features of the soil and plant population parameters (abundance, biomass, and ontogenetic composition). Some indices of the content of mineral substances in the population and soil proved to be difficult to interpret unambiguously.     

Aboveground phytomass and rate of plant debris decomposition in herbaceous communities exposed to soil pollution with heavy metals

Consideration is given to production and decomposition processes in herbaceous communities exposed to chemical pollution with heavy metals in the Middle Urals. High variation in the aboveground phytomass of agrobotanical groups (legumes, forbs, grasses) is due to spatial heterogeneity of soil pollution levels and consequent changes in the species composition of plant communities in the areas studied. Therefore, nonparametric statistical methods have been used (Kruskal–Wallis test with subsequent pairwise comparisons by Wilcoxon–Mann–Whitney with Bonferroni correction for multiple comparisons). The phytomass of legumes remains unchanged in the increasing pollution gradient, while the contribution of forbs to the total phytomass decreases and that of grasses increases. Soils rich in nutrient elements can maintain a high rate of plant debris decomposition, counterbalancing the adverse effect of increased heavy metal concentrations on relevant processes. The balance between production and mineralization processes provides for the sustainable, long-term existence of herbaceous communities under conditions of intense pollution of the natural environment.     

Accumulation and release of 241Am by a macrophyte of the Yenisei River (Elodea canadensis)

The source of radioactive contamination of the Yenisei River floodplain, including contamination with transuranic elements, is the Mining-and-Chemical Combine of the Russian Ministry of Atomic Energy, which has for many years been producing weapons-grade plutonium. Transuranic elements have been detected not only in the soil and sediment of the river but also in the biomass of aquatic plants. This work is an investigation of accumulation and release of 241Am by a submerged macrophyte of the Yenisei River (Elodea canadensis) in laboratory experiments. In 2000-2003, laboratory experiments were carried out with biomass of E. canadensis Mich. and filtered river water. The samples were collected from the Yenisei River upstream of the discharge of the Combine's radioactive effluent. The experiments showed that 241Am is accumulated by Elodea biomass: the activity concentration of 241Am can reach 3280+/-240 Bq/g, with the concentration factor for 241Am 16 600+/-2200l/kg. Results of chemical fractionation have proved that in the course of 241Am accumulation by Elodea biomass, 241Am tightly bound to biomass increases from 11% to 27% of the total 241Am in the biomass. Release of 241Am from the decaying Elodea biomass has been evaluated experimentally. By the end of the experiment (lasting up to 127 days), the Elodea plants had lost up to 65% of their initial 241Am activity and the rate of 241Am release into the water environment reached 23 Bq/day.     

Micronutrient composition of plants in the Polar Urals under contrasting geochemical conditions

Natural variation in the level of micronutrients in plants and soils of the Polar Urals depending on the types of bedrocks has been evaluated. The contents of Fe, Mn, Zn, Cu, Ni, Cr, and Co have been determined by the atomic absorption method in 156 plant species of 25 families and in 38 soil samples. It has been found that the mineral composition of plant species varies depending on edaphic conditions. Taxon-specific features in the accumulation of chemical elements in plants of the Polar Urals have been revealed for the first time on the basis of a large amount of data.     

鄱阳湖典型苔草湿地生物量季节变化及固碳功能评价

为进一步评估鄱阳湖湿地碳平衡,量化湿地固碳功能,于2009年9月～2011年5月,在鄱阳湖南矶湿地国家级自然保护区,选择以灰化苔草为建群种的洲滩湿地,采取收获法测定了灰化苔草4个生长季的地上、地下生物量及净初级生产力(NPP)。结果表明：1）苔草地上、地下生物量均具有明显的季节变化模式,变化范围分别为14608～1 77067 、1 80627～4 03256 g/m2;地下生物量与地上生物量的比例变化范围为208～1744,平均值为519。2）苔草地上地下生物量、NPP均表现为春季高于秋季。3）受洲滩淹水时间影响,苔草生物量、NPP具有显著的年际差异, 2010～2011年度苔草NPP仅相当于2009～2010年度的625%;NPP的下降地上部分较地下部分更明显。4）鄱阳湖湿地苔草固碳潜力巨大,2个年度固碳量分别为1 92383,1 23121 gC/m2     

Patterns of the accumulation of chemical elements in the plankton of a fresh water body

For the first time, comparative data are presented on the distribution of 70 chemical elements occurring in the Beloyarsk Reservoir between the water and the plant and animal components of the plankton (phyto- and zooplankton). All these elements are ranked into groups according to the values of accumulation coefficient (AC) for phytoplankton and zooplankton. For the sum of all chemical elements, a significant positive correlation has been revealed between their content in the water and in the plankton. It has been shown that elements with even atomic numbers and concentrations in the plankton below 7 ??g/g dry weight are accumulated by the plankton in significantly larger amounts than such elements with odd atomic numbers. This fact confirms the classic concept developed by A.P. Vinogradov that the prevalence of chemical elements in the biosphere depends on their position in the periodic system.     

The use of biomass production and allometric models to estimate carbon sequestration of <Emphasis Type="Italic">Jatropha curcas</Emphasis> L. plantations in western Burkina Faso

The topic of carbon sequestration in plants has received much attention recently due to concerns about global climate change, which is being exacerbated by deforestation. In the early days of the global bioenergy boom, the private sector and non-government organizations enthusiastically promoted the planting of Jatropha curcas L. as a key candidate shrub species for the production of bioenergy in West Africa. This study investigates the aboveground biomass production and carbon sequestration potential of J. curcas, which is already widely cultivated for the production of oil seeds, biodiesel and biokerosene. The specific objective is to use a destructive method to develop allometric prediction equations of the aboveground biomass production of J. curcas plantations. 38 J. curcas shrubs were harvested and weighed in order to estimate biomass production. These data were used to develop allometric equations for the estimation of wood, leaf and total aboveground biomass production. The best-fit models found for estimating shrub component biomass and total aboveground biomass production were of the power form. All of the regression equations relating the prediction of leaf biomass, wood biomass and total aboveground biomass with J. curcas diameter at 20 cm above the ground (D) were statistically significant (p < 0.001) and also presented the highest goodness of fit (high R ²). The aboveground biomass carbon content was estimated using the ash method. Carbon content in leaves and wood was, respectively, 48 and 54 %. The current established allometric equations can be helpful to provide a rapid estimation of the aboveground biomass and C stock for J. curcas biofuel projects in semi-arid conditions.     

40K/137Cs discrimination ratios to the aboveground organs of tropical plants

In the present work, the accumulation of caesium and potassium in aboveground plant parts was studied in order to improve the understanding on the behaviour of monovalent cations in several compartments of tropical plants. We present the results for activity concentrations of (137)Cs and (40)K, measured by gamma spectrometry, from five tropical plant species: guava (Psidium guajava), mango (Mangifera indica), papaya (Carica papaya), banana (Musa paradisíaca), and manioc (Manihot esculenta). Caesium and potassium have shown a high level of mobility within the plants, exhibiting the highest values of concentration in the growing parts (fruits, leaves, twigs, and barks) of the woody fruit and large herbaceous shrub (such as manioc) species. In contrast, the banana and papaya plants exhibited the lowest levels of (137)Cs and (40)K in their growing parts. However, a significant correlation between activity concentrations of (137)Cs and (40)K was observed in these tropical plants. The (40)K/(137)Cs discrimination ratios were approximately equal to unity in different compartments of each individual plant, suggesting the possibility of using caesium to predict the behaviour of potassium in several tropical species.     

巢湖藻华易堆积区蓝藻时空分布的研究

巢湖西半湖采样分析结果表明夏季蓝藻水华主要集聚于湖滨带。因此选择西半湖藻华易堆积的区域,并监测在风力驱使下蓝藻水华的时空分布规律,分析湖滨带浮游植物生物量与理化因子的相关性。结果表明：湖滨带水华生物量的分布容易受到风向和天气的影响;水体的叶绿素a浓度与总氮（TN）、总磷（TP）和高锰酸钾指数（CODMn）呈显著的正相关（p<001）;湖滨带水体中微囊藻（Microcystis）的生物量几乎占据水体总浮游植物生物量的95%以上,而且越靠近湖岸带微囊藻的生物量所占的比例越大。据此,可以选择湖滨带水华易聚集区作为蓝藻水华尤其是微囊藻去除的重点区域,以有效地削减蓝藻水华污染,从而为巢湖水生态系统的修复创造条件     

Screening plant species native to Taiwan for remediation of 137Cs-contaminated soil and the effects of K addition and soil amendment on the transfer of 137Cs from soil to plants

This study aims to screen plant species native to Taiwan that could be used to eliminate (137)Cs radionuclides from contaminated soil. Four kinds of vegetables and two kinds of plants known as green manures were used for the screening. The test plants were cultivated in (137)Cs-contaminated soil and amended soil which is a mixture of the contaminated one with a horticultural soil. The plant with the highest (137)Cs transfer factor was used for further examination on the effects of K addition on the transfer of (137)Cs from the soils to the plant. Experimental results revealed that plants cultivated in the amended soil produced more biomass than those in the contaminated soil. Rape exhibited the highest production of aboveground parts, and had the highest (137)Cs transfer factor among all the tested plants. The transfer of (137)Cs to the rape grown in the soil to which 100 ppm KCl commonly used in local fertilizers had been added, were restrained. Results of this study indicated that rape, a popular green manure in Taiwan, could remedy (137)Cs-contaminated soil.     

氮素形态及浓度对互花米草生长的影响

近年来，由于人类生产生活的影响，以化肥农药使用为主的面源污染和以工业排放为主的点源污染日益加剧，全球尤其是海岸带氮含量逐渐升高，对滨海植被的生长产生了巨大的影响。在这个背景下，通过温室模拟实验研究不同供氮水平对互花米草的影响，对研究氮对入侵植物的影响作用机制有重大意义。互花米草在两种氮肥不同氮水平处理下，株高、叶面积、生物量等生长指标以及根冠比、根长/株高等指标的变化情况不同。结果表明：随着氮量增加，米草株高、叶面积、总生物量和地上部分生物量呈先上升后下降的趋势，地下部分生物量、根冠比和根长/株高比则呈下降趋势；各项指标在无机氮肥不同氮水平处理之间存在显著差异，但在有机氮肥的各处理间差异无显著性。这说明适当的供氮水平有利于互花米草的生长，而高氮则抑制其生长     

Growth response of Sesbania rostrata and S. cannabina to sludge-amended lead/zinc mine tailings. A greenhouse study

Legumes are ideal for revegetation of metal-mined wastelands which lack nitrogen (N). A greenhouse study was conducted to investigate the feasibility of using Sesbania rostrata and S. cannabina for the reclamation of lead/zinc (Pb/Zn) mine tailings and to evaluate the effects of organic amendment using sewage sludge (0%, 25%, 50%, and 75%, v/v). The results showed that both species could continue to grow on the highly toxic tailings substrata for at least 80 days, although their growth suffered from adverse effects. That S. rostrata with stem and root nodules had better growth (biomass, growth rates, and biomass of nodules) than S. cannabina suggested that S. rostrata is a better choice as a pioneer species for revegetation of the mine tailings. Stem nodules had less obvious adverse effects imposed by tailings than root nodules. Application of sewage sludge increased contents of total carbon (C), N, phosphorus (P), and potassium (K), and reduced total Zn, Pb, Cd, and DTPA-extractable Pb and Cd in tailings substrata. These, in turn, reduced metal (Zn, Pb, and Cd) uptake and accumulation in plant tissues, and improved plant growth performance, including biomass, growth rates, stem nodulation. Fifty percent (v/v) of sludge application rate was the best loading rate for plant growth.     

Adaptive responses of scots pine to the impact of adverse abiotic factors on the rhizosphere

The impact of long-term seasonal soil freezing, drought, and waterlogging on the rhizosphere of young Scots pine trees (Pinus sylvestris L., age class 1) has been simulated in experiments. The results have shown that cold stress exposure leads to reduction of the rates of linear and radial tree growth and of chlorophyll content in needles, a shift in the peak of starch content, and initiation of free amino acid deposition in the aboveground plant parts. Drought activates utilization of carbohydrate reserves and amino acid accumulation in the root bast, whereas soil waterlogging stimulates deposition of carbohydrates but causes a decrease in the levels of chlorophyll and amino acids in all plant tissues.     

Management of sludge from fish ponds at the edge of the Itaparica Reservoir (Brazil): an alternative to improve agricultural production

Sludge generated in intensively managed tilapia fingerling breeding ponds near the Itaparica Dam in the semi-arid Brazilian northeastern region was tested as a soil conditioner to produce lettuce in an effort to mitigate the present environmental impact of the deposition of this sludge, thereby giving it a productive destiny. A greenhouse experiment was performed by mixing the sludge with a Haplic Planosol topsoil, a characteristic soil of the region, so that the sludge corresponded to 0, 25, 50, 75, and 100% of the mixture (substrate). The experiment was set up as a randomized block design with five blocks, each with three pots (5-kg substrate per pot) of the five sludge proportion treatments. One lettuce plant was transplanted into each pot, maintained under greenhouse conditions, and harvested 35 days after transplanting. Sludge, soil, and the substrates were evaluated for nutrient concentration and physical characteristics. Green and dry weights, stem diameter, and nitrogen, phosphorus, and potassium concentrations in the aboveground parts of the lettuce plants were determined. Sludge incorporation into the substrate improved its chemical and physical characteristics. The lettuce plants grew best in the substrate with 75% sludge, increasing its biomass production by 50% and more than doubling its nitrogen uptake.     

Radiocesium contamination behavior and its effect on potassium absorption in tropical or subtropical plants

The accumulation and long-term decline of radiocesium contamination in tropical plant species was studied through measurements of gamma-ray spectra from pomegranate (Punica granatum) and chili pepper (Capsicum fructescens) trees. The plants were originally grown at a (137)Cs contaminated site (where a radiological accident occurred in the city of Goiania, Brazil, in 1987), and transplanted to uncontaminated soil, so that the main source of contamination of the new leaves and fruits would be the fraction of the available radiocesium in the body of the plants. Measurements of (137)Cs and (40)K concentrations along the roots, main trunk, twigs, leaves and fruits before and after the transplant process of both plant species indicated a direct competition between Cs and K ions, suggesting that these elements could have a common accumulation mechanism. Cesium transfer factors from soil to pomegranate, green and red chili pepper fruits were evaluated as 0.4 +/- 0.1, 0.06 +/- 0.01 and 0.05 +/- 0.01, respectively. Biological half-life values due to (137)Cs translocation from the tree reservoir (BHL(T)) were calculated as 0.30 years for pomegranate, 0.12 years and 0.07 years for red and green peppers, respectively.     

半月周期的潮汐对滨海湿地土壤理化性质的影响

周期性的潮汐是滨海湿地重要的水文特征,为了探讨潮汐的半月周期(包括小潮期和大潮期)对土壤理化性质的影响及可能的机制,于2009年7月中下旬测定了长江口崇明东滩湿地土壤理化性质在小潮期和大潮期交替周期内的变化规律。结果表明,与小潮期相比,由于频繁的潮水淹没,大潮期0～5 cm土壤含水量的增加量从低潮滩向高潮位依次为:44.8%、18.5%、10.9%和14.3%,5～10 cm含水量的增加量从低潮滩向高潮位依次为:19.2%、9.8%、12.6%和16.2%,10～20 cm则依次为:5.6%、6.1%、2.5%和7.3%。大潮期,从低潮滩向高潮滩增加的盐度依次为0.18、0.13、0.10和0.09 ms·cm^-1,增加的硫酸盐依次为0.32、0.21、0.16、0.13 mg·g^-1。与小潮期相比,大潮期氧化还原电位(Eh)显著降低;土壤容重、pH、可溶性有机碳和可溶性氮在大小潮期间无明显差异。此外,在潮汐的半月周期内,低潮滩土壤比高潮滩有更高淹水频率和更长淹水时间,受潮水的影响更明显,大潮期低潮滩土壤含水量、盐度和硫酸盐的增加幅度大于高潮滩,低潮滩土壤Eh降低幅度则小于高潮滩。半月周期的潮汐可以显著影响滨海湿地的部分土壤理化性质,且不同潮位的土壤性质对潮汐的响应程度不同,进而可能会对湿地植物生长和相关生态过程起到重要的调控作用。     

Effect of heavy metal pollution on plant communities of the Tanalyk River,the Bashkir Transural region

Geobotanical analysis of aquatic and wetland plant communities of the Tanalyk River has been performed in the zone of impact from the abandoned Kul-Yurt-Tau pyrite mine. The results show that pollution of the river with highly mineralized runoff leads to a decrease in the β-diversity and synthetic characteristics of plant communities (α-diversity, total coverage, and herb layer height) and in the aboveground phytomass of dominant species.     

Reproductive allocation patterns in different edaphic types populations of <Emphasis Type="Italic">Haloxylon ammodendron</Emphasis> in Gurbantünggüt desert

The reproductive allocation (RA) of Haloxylon ammodendron (C.A. Mey.) Bunge was studied in different edaphic types of the Gurbantünggüt desert. Results showed that the RA had significant hierarchical variation. Both RA and reproductive output (RO) were size-dependent, and relationships between above-ground total biomass and RA/RO were represented by linear or exponential equations. The RA in loam increased with aboveground total biomass increased. However, the RA showed a faint decrease in gravel soil and significant decrease in sandy soil with aboveground total biomass increased. Then, the stability of the population was analyzed in three edaphic types.     

Grazing,forest density,and carbon storage: towards a more sustainable land use in Caatinga dry forests of Brazil

Grazing is the main land use in semi-arid regions of the world, and sustainable management practices are urgently needed to prevent their degradation. However, how different grazing intensities affect forest density and ecosystem functions is often not sufficiently understood to allow for management adaptations that safeguard the ecosystems and their functions in the long run. We assessed the aboveground carbon stocks and plant densities along a grazing gradient in the semi-arid seasonally dry tropical forest of north-eastern Brazil (Caatinga). On 45 study plots, we analysed the aboveground carbon stocks of the vegetation and determined forest density and recruitment as well as the population structure of the most abundant tree species. Grazing intensity was accounted for based on the weight of livestock droppings and classified as low, intermediate, or high. Mean aboveground carbon stock was 15.74?±?1.92 Mg ha^?1 with trees and shrubs accounting for 89% of the total amount. Grazing at high intensities significantly reduced aboveground carbon stocks of herbs but not of other plant functional types. Instead, aboveground carbon stocks of trees and shrubs were negatively related to altitude above sea level, which is a proxy for reduced water availability along with lower anthropogenic impact. The population structure of the most common tree species was characterised by abundant recruitment, irrespective of grazing, whereas the recruitment of less frequent woody species was negatively affected by grazing. Overall, our data imply that grazing and forage management need to be adapted, including the reduction of free-roaming livestock and storage of fodder, to maintain carbon storage and forest density.     

Arbuscular mycorrhizal fungi decrease radiocesium accumulation in Medicago truncatula

The role of arbuscular mycorrhizal fungi (AMF) in plant radiocesium uptake and accumulation remains ambiguous. This is probably due to the presence of other soil microorganisms, the variability of soil characteristics and plant nutritional status or the availability of its chemical analogue, potassium (K). Here, we used an in vitro culture system to study the impact of increased concentration of K on radiocesium accumulation in non K-starved mycorrhizal and non-mycorrhizal Medicago truncatula plants. In the presence of AMF radiocesium uptake decreased regardless of the concentration of K, and its translocation from root to shoot was also significantly lower. Potassium also reduced the accumulation of radiocesium in plants but to a lesser extent than mycorrhization, and without any effect on translocation. These results suggest that AMF in combination with K can play a key role in reducing radiocesium uptake and its subsequent translocation to plant shoots, thereby representing good potential for improved phytomanagement of contaminated areas.