Inorganic chemical investigations in the forest biosphere reserve near Kalinin,USSR

Lanthanides (rare-earth elements) were quantitatively determined by atomic emission spectrometry/inductively coupled plasma (AES/ICP) in various plants (Picea abies, Vaccinium vitis-idaea, Vaccinium myrtillus, Polytrichum commune, Sphagnum spec., and Hypogymna physodes) collected in the Forest Biosphere Reserve 350 km northwest of Moscow (USSR). Compared with previously established background values for lanthanide elements in central Europe, the rare elements determined in the USSR samples appear in lower concentrations. The lichen Hypogymna physodes can be characterized as an extreme accumulator of lanthanide elements up to a factor of ten compared to the other plant species collected in the Forest Biosphere Reserve. With regard to the lanthanide contents in plants collected in a German reference forest ecosystem, it can be seen, that the German samples represent without exception higher lanthanide values. Leaves of Vaccinium vitis-idaea display contents 3–4 times higher, leaves of Vaccinium myrtillus show concentrations higher by a factor of about 0.3, approximately twice the contents were determined in the German samples of Polytrichum formosum and P. commune, and the values in the German samples of the Sphagnum species are about 3 times that of the Soviet samples. As pointed out for pollution by heavy metals in part I of this series, the Forest Biosphere Reserve is generally characterized by lower contents of lanthanides in the vegetation cover than a comparable forest ecosystem (Grasmoor near Osnabrück, F.R.G.) in central Europe.     

Taxonomic character of plant species in absorbing and accumulating alkali and alkaline earth metals grown in temperate forest of Japan

Summary Absorption and accumulation of alkali (Li, Na, K, Rb, Cs) and alkaline earth (Mg, Ca, Sr, Ba) metals were investigated as taxonomic characteristics (in 62 plant species). Leaf and soil samples were collected from 9 sites in temperature forest in Japan and the above mentioned elements were analyzed. Considerable differences were found among species in their ability to accumulate alkali and alkaline earth metals. Very high concentrations of Li (45 ppm, D.W.), K (37×10³ ppm), Rb (159 ppm) and Cs (8.2 ppm) were detected inLastrea japonica which were about 412, 12, 27 and 6 times higher than those of the species with the lowest concentrations. Na content was high inAcer micranthum (358 ppm) which was 16 times higher than species with the lowest concentration. Other species containing high levels of alkali metals wereHydrangea macrophylla, Struthiopteris niponica, Clethra barbinervis. Mean discrimination ratio (D.R.) for all investigated plant species for Li, Na, Rb, and Cs to K were 1.7, 0.44, 0.9 and 1.8 respectively. High concentrations of alkaline earth metals Ca (36×10³ ppm), Sr (345 ppm), and Ba (241 ppm) were found in the leaves ofHydrangea paniculata which were about 31, 84, and 72 times higher than those for the species with the lowest concentration. Mg was very high inStruthiopteris niponica (83×10² ppm). Other species with high concentrations of alkaline earth metals belonged to the genus Viburnum. Mean D.Rs. for Mg, Sr, and Bavs Ca were 1.0, 0.7 and 0.08. Principal component analysis of interrelationships between the mineral content in leaf tissues indicated that these elements could be classified into 2 groups with respect to their accumulation behavior in plants. The alkali metals K, Li, Rb, and Cs behaved similarly in their accumulation in leaves but Na behaved independently. Alkaline earth metals Ca, Mg, Sr, and Ba were also found to behave similarly in their accumulation. Factors scores of 1st and 2nd components revealed three groups of plant species: alkaliphilic, alkaline earthphilic, and neutral (non-accumulators).     

鼎湖山南亚热带地区植物的叶片矿质元素

本文分析了64种植物叶片中19种矿质元素的含量,讨论了不同生活型植物对矿质元素的吸收和积累的影响。研究表明:64种植物叶片的19种矿质元素的频数分布呈对数正态分布。不同植被型及生活型,子叶数及光合途径对叶片矿质元素含量和组成有显著的影响。密林植物含较多P和Mg,有较高的微量元素/大量元属比;疏林植物含较多Al和Mn;木本型植物缺Mo;草本型植物积集较多的K、Ca、Si、Mg、P和Ti。草本中的双子叶植物平均矿质元素总量高于单子叶,尤以Ca与B较为明显。单子叶中的C_4植物叶片含较多的Na。     

Contrasting strategies for UV-B screening in sub-Arctic dwarf shrubs

The content and distribution of UV-absorbing phenolic compounds was investigated in leaves of three species of Vaccinium co-existing at a site in north Sweden. Vaccinium myrtillus L., Vaccinium vitis-idaea L., and Vaccinium uliginosum L. exhibit markedly different strategies, in terms of localization and content of leaf phenolics and in their responses to UV-B enhancement. Plants were exposed to either ambient radiation or to enhancement of UV-B corresponding to 15% (clear sky) depletion of stratospheric ozone for approximately 10 years prior to commencement of this study. Vaccinium myrtillus contained the highest concentration of methanol-extractable UV-B-absorbing compounds, which was elevated in plants exposed to enhanced UV-B. Fluorescence and confocal laser scanning microscopy showed that these compounds were distributed throughout the leaf, and were particularly concentrated in chlorophyll-containing cells. In V. vitis-idaea, most phenolic compounds were cell wall-bound and concentrated in the walls of the epidermis; this pool increased in response to UV-B enhancement. It is suggested that these two plants represent extreme forms of two divergent strategies for UV-B screening, the different responses possibly being related to leaf longevity in the two species. The response of V. uliginosum was intermediate between the other two, with high concentrations of cell wall-bound phenolics in the epidermis but with this pool decreasing, and the methanol-soluble pool tending to increase, after exposure to enhanced UV-B. One explanation for this response is that this plant is deciduous, like V. myrtillus, but has leaves that are structurally similar to those of V. vitis-idaea.     

Inorganic chemical investigations in the Forest Biosphere Reserve near Kalinin,USSR

To get a first impression of the degree of pollution in the Forest Biosphere Reserve 350 km northwest of Moscow, samples of Polytrichum commune and peat profiles were measured by ICP/MS after decomposition by high-pressure ashing. Comparing the results with data found in similar systems in Central Europe the Forest Biosphere Reserve can be described than medium-polluted by heavy metals. Pb shows lower values as in comparable systems in Germany, due to the fact of lower traffic density in Sowjetunion. The status of the nutritional elements Ca, Mg and K is in the same order of magnitude as found in German forest ecosystems.     

Schwermetallakkumulation im Sphagnetum magellanici aus Hochmooren der Bundesrepublik Deutschland

• 1 . In 30 Hochmooren der Bundesrepublik Deutschland werden verschiedene Arten des Sphagnetum magellanici auf ihren Gehalt an Pb, Cd, Cu, Zn und Mn untersucht (Sphagnum magellanicum, Sphagnum rubellum, Polytrichum strictum, Vaccinium oxycoccus).
• 2 . Während die Sphagnen besonders viel Pb anreichern, zeigt Polytrichum strictum hohe Cu-Gehalte. In Vaccinium oxycoccus treten sehr hohe Mn-Konzentrationen auf.
• 3 . Von Vaccinium oxycoccus werden Blättchen, Sprosse und Wurzeln getrennt untersucht. Pb, Cd, Cu und Zn reichern sich besonders in den Wurzeln an, Mn dagegen in den Blättchen.
• 4 . Es werden darüber hinaus vertikale Torfprofile auf ihr Schwermetallverteilungsmuster untersucht. Während sich vor allem Pb und Cd, aber auch Cu und Zn in den unteren Moosabschnitten und in den anschließenden Torfschichten anreichern, ist die Mn-Konzentration an der Polsteroberfläche am höchsten.
• 5 . In der Schwermetallbelastung der Hochmoore treten deutliche regionale Unterschiede auf. Die höchste Pb-Belastung findet sich in den Hochmooren des Harzes, während die Pb-Belastung in NW-Deutschland, im südlichen Schwarzwald und im westlichen Alpenvorland am geringsten ist.
• 6 . Beim Schwermetallgehalt in Sphagnum magellanicum bestehen zwischen Pb einerseits und Cd, Cu und Zn andererseits signifikante Korrelationen. Eine Sonderstellung unter den gemessenen Mikronährstoffen nimmt Mn ein.
• 7 . Die Jahresnettoproduktion von Sphagnum magellanicum wird mit verschiedenen Methoden bestimmt. Sie beträgt im Mittel 3,0 g. dm^?2 a^?. Daraus lassen sich Immissionsraten für die einzelnen Schwermetalle berechnen, die für Cd und Zn rund die Hälfte der Emission dieser Metalle betragen.

Die Arbeit wurde durch die Deutsche Forschungsgemeinschaft gefördert, der wir an dieser Stelle besonders danken.     

Carbohydrate and lipid levels in two Polytrichum moss species growing on the Alaskan tundra

Two tundra Polytrichum moss species were sampled in the field near Barrow, Alaska, three times during the growing season. Lipid, sugar, and starch concentrations of the green above ground shoots and below ground rhizomes were analyzed. Lipid and TNC (sugar + starch) concentrations were higher in Polytrichum commune growing on raised polygon rims than in Polytrichum alpinum. There were no significant differences between the two populations of P. alpinum. Green parts had significantly higher lipid concentrations than rhizomes in P. commune but not in P. alpinum. Both species had significantly higher sugar concentration in green shoots and higher starch concentrations in the rhizome and sugar concentration varied significantly in both species. Seasonal variation of TNC concentration levels were significant only in P. commune. A statistically significant positive relationship was found between lipid and TNC concentration while a stronger statistically significant negative relationship was found between sugar and starch concentration. The first is interpreted as an adaptation to drought in surface waxes and osmoticum while the second is interpreted as conversion indicator depending on tissue and use. Polytrichum mosses resemble evergreen vascular plants in their seasonal stability of these compound groups.     

Soil influence on Cu and Co uptake and plant size in the cuprophytes Crepidorhopalon perennis and C. tenuis (Scrophulariaceae) in SC Africa

Cuprophytes are plants that mostly occur on Cu-rich soil in SC Africa. Crepidorhopalon perennis is endemic of a single site. C. tenuis has a broader niche, from normal to Cu-rich soil. Both have been considered as Cu-Co accumulators. We examined soil factors controlling heavy metal accumulation and plant fitness in natural populations. Plant mass and element concentrations in plants and soil were determined in 153 samples from five populations of C. tenuis on copper soil (CTC), two on normal soil (CTN) and the single population of C. perennis (CP). Soil in Cu-sites had higher concentrations of Ca, Mg, P, Mn, Zn, Cu, Co. Plants from Cu-sites were larger and had higher Cu and Co content, and lower Mg, Mn and Ca. Cu in shoots was influenced positively by Cu and Mn and negatively by Ca in the soil. Co in shoots was influenced positively by Co and negatively by Mn and Fe in the soil. Shoot mass was influenced positively by Cu and Mn (CT) or by Cu and Co (both species pooled) in the soil. The results suggest that C. tenuis and C. perennis are genuinely cuprophilous species. Large variation in metal accumulation in shoots can be accounted for by synergistic and antagonistic interactions among several heavy metals, yielding specific accumulation patterns in different populations.     

Element concentrations in mosses and surface waters of western Canadian mires relative to precipitation chemistry and hydrology

Concentrations of N, P, S, Na, K, Mg, Ca, Mn, Fe, Cu, Cd, Zn, Pb, Al, and AIA (acid insoluble ash) m mosses (three Sphagnum species and Tomenthypnum nitens, all hummock species) from a variety of mires, both ombrotrophic and minerotrophic, in the coastal western and central parts of Canada are considered in relation to surface water pH and concentrations of Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl⁻, and SO₄^2- Distinct west-east concentration gradients were present for most elements in both mosses and water, but there were correlations between surface water and moss concentrations only for Ca and Mg
On ombrotrophic sites and sites characterized by poor fen vegetation, wet deposition is the main source of elements in the surface water On rich fen sites, additional Ca and Mg from surrounding soils change the elemental proportions We conclude that hydrochemically the limit between poor and rich fen sites is more decisive than between bog and fen The increase in Ca may give brown mosses a competitive advantage over Sphagnum
Moss concentrations of Na and Mg are the only ones decreasing inland The constancy or inland increase of moss elemental concentrations may depend on either an increasing atmospheric supply (e g Pb), differences in moss growth rates (especially N, P, and K) or site conditions related to the water regime (e g Fe and Al)     

Contents of macro-, microelements and long-lived radionuclides in the medicinal plants belonging to the wetland community of Siberian region,Russia

Studied contents of macro-, microelements and long-lived radionuclides in the following medicinal plants belonging to the wetland community of Siberian region, Russia: Sphagnum fuscum (Schimp.) Klinggr., Sphagnum balticum (Russ.) Russ. ex С. Jens., Polytrichum strictum Brid., Pinus sylvestris L., Pinus sibirica Du Tour, Betula pubescens Ehrh., Andromeda polifolia L., Ledum palustre L., Oxycoccus palustris Pers., Rubus chamaemorus L., Vaccinium uliginosum L., Comarum palustre L., Chamaedaphne calyculata (L.) Moench. Samples were collected in the sphagnum wetlands of Tomsk region and Khanty-Mansi Autonomous Okrug. For the purpose of research, we used roots, shoots and bark of the plants in the Pinophyta and Magnoliophyta species and turf of the Bryophyta species. The content of macro-, microelements in the plants was determined by an atomic emission spectrometer with inductively coupled plasma “iCAP 6300 Duo” of the “Thermo Scientific” company. The specific activities of the long-lived radionuclides Th-232, K-40, Ra-226, Cs-137 were measured by a gamma-ray spectrometric complex with a high purity germanium semiconductor detector by “ORTEC” (AMETEK) and a digital analyser “ORTEC DSPEC LF”. The obtained results of the element content are useful when selecting a medicinal plant species (or part thereof) which may be used in preparation of new medicinal drugs.     

沿干旱梯度小叶锦鸡儿灌丛化对草本植物叶片矿质元素浓度及地上生物量累积的影响

草原灌丛化通过改变物种之间的相互作用深刻影响着群落的结构和功能。然而,当前有关灌木如何影响不同功能群草本植物对矿质元素吸收和累积的研究仍明显不足。在内蒙古草原沿干旱梯度选取了4个研究地点,对比分析了小叶锦鸡儿(Caragana microphylla)灌丛斑块内和斑块外群落中禾草和非禾草功能群植物叶中矿质元素浓度以及地上生物量生产的差异,旨在阐明干旱和灌木对群落草本植物叶元素累积的影响,揭示灌草间相互作用的元素利用特征及其随干旱梯度的变化。结果显示：1)随干旱加剧,灌丛斑块内的非禾草功能群植物地上生物量保持恒定,但叶中的K、Ca、Mg、Fe、Mn和Cu元素浓度显著增加(P<0.05)。该结果表明群落中的非禾草功能群植物通过提高叶中的矿质元素水平来抵御和适应干旱胁迫。2)随干旱加剧,灌丛对非禾草功能群植物地上生物量,叶中Ca、Fe、Cu和Zn,禾草功能群植物叶中的P的累积影响从负(RII<0)或中性(RII=0)转变为正效应(RII>0)。该结果与胁迫梯度假说相符,表明灌木对草本植物的促进效应随干旱胁迫加剧而增加。3)灌丛的“沃岛”效应是驱动灌木对草本植物元素累积正效应...     

Mineral composition ofCuscuta nevadensis Johnston (dodder) in relationship to its hosts

Summary The mineral composition of 16 samples of dodder (Cuscuta nevadensis Johnston) and leaves of eight species of its host plants collected from the northern Mojave Desert were examined to determine relationships between parasitism and transport of mineral elements from the host to the parasite. The K concentration of dodder was fairly constant for a wide range of host plants. It was sometimes less than and sometimes greater than that of the host. The concentrations of Ca, Mg, B, Mn, Mo, and Sr in dodder were always much lower than those of leaves of host plants. Those of Fe, P, and Al were sometimes higher. Sodium was generally excluded from dodder regardless of host concentration. Positive and significant correlation coefficients were obtained for concentration in doddervs concentration in leaves of host plants for P, Na, Ca, Mg, Cu, Mn, Mo, Sr, Ba, and Li. The coefficient of variation was less in the dodder than in leaves of the different host plants for 7 of 17 metals.     

Effects of enhanced UV-B radiation and elevated carbon dioxide concentrations on a sub-arctic forest heath ecosystem

An experiment is described which studies the effects of enhanced UV-B radiation (simulating a 15% reduction in the Ozone layer) and elevated atmospheric concentrations of CO₂ (600 ppm) on the dwarf shrub layer of a sub-arctic forest heath ecosystem at Abisko, North Sweden. The experimental treatments were first applied in 1993, and have covered most of the snow-free season (late May to early September) 1993–1995. Effects of the treatments on the four dwarf shrub species have been recorded largely using non-destructive measures (Vaccinium uliginosum, Vaccinium myrtillus – deciduous species and Vaccinium vitis-idaea and Empetrum hermaphroditum – evergreen species). Effects of the treatments on stem growth and leaf thickness have so far been small, although CO₂ treatments initially stimulated stem extension in Vaccinium myrtillus 1993 and depressed growth in V. vitis idaea in 1994 and E. hermaphroditum during 1995. UV-B treatments stimulated fruit production in V. myrtillus in both 1994 and 1995, but there was no effect on reproductive phenology. There were also marked effects of UV-B treatments on insect herbivory in the deciduous dwarf shrubs; with leaf area loss being greater than the control in the UV-B treatment in V. myrtillus and less in V. uliginosum. The results point to the possibility of important effects of the treatments on physiological and chemical processes within the plants. The ecological results of such effects may not be immediately apparent, but may be far reaching, pointing to the need for long-term in situ experimentation in predicting the effects of these global change variables.     

Nutrient Accumulation in the Fruits of Two Species of Seagrass, Posidonia australis and Posidonia sinuosa

The accumulation is described of N, P, K, S, Ca, Mg, Na, Fe,Zn, Mn and Cu in the developing pericarp and seed of two speciesof seagrass. Both species showed essentially the same patterns,which resemble those of herbaceous terrestrial plants. Therewas a close relation between dry matter and nutrient accumulation.N, P, K, Fe, Zn, Mn and Cu accumulated in the fruit againstlarge concentration gradients, with discrimination against Na.Seeds accumulated N, P and trace elements to a greater extentthan pericarps and other plant parts; P was apparently retrievedfrom pericarps to a greater extent than other elements. Calculationswere made of the losses of these elements from seagrass meadowsin shed fruits. Posidonia spp., seagrass, nutrient accumulation in fruits     

Distribution of nutrients and phytotoxic metal ions in the soil and in two forest floor plant species of a beech (Fagus sylvatica L.) stand

In a beech (Fagus sylvatica L.) stand in north-west Germany vegetation of two transects (25m:1m and 20m:1m) was mapped and contents of macronutrients (Ca, Mg and K), micronutrients (Fe, Mn, Zn and Cu), and potentially phytotoxic metals (Pb, Cd, Ni and Al) were measured in different soil compartments and in roots, rhizomes, stems and leaves of two forest floor plant species (Mercurialis perennis L. and Polygonatum multiflorum L.). NH₄Cl extractable cation contents, pH and other soil variables were also determined.The highest macronutrient contents could be found in the leaves of M. perennis and P. multiflorum. Heavy metals and Al accumulated in the roots. Correlation analysis suggests a considerable translocation of Zn and Cd between below- and above-ground organs of both investigated forest floor plants. No significant correlation was found between the contents of the other elements in the below- and above-ground parts.Available data indicate a considerable uptake by the plants not only of nutrients, but also of heavy metals from the upper mineral soil. Amounts of heavy metals and Al solubilized in the presence of NH₄Cl increased with decreasing pH, whereas levels of soluble Ca and Mg were maximal at high pH-values of the extracts. It can be concluded that element uptake in the investigated plants is indirectly controlled by the pH of the upper mineral soil.     

江苏海岸带陆生盐土植物矿质元素含量的特点及生物循环

陆生盐土植物在生长过程中吸收积累了大量的Cl和Na;从海向陆随着土壤和植被的生态演替,植物中Cl和Na的浓度逐渐降低;N与Cl、Na有相似的水平分布规律;植物种类是影响元素吸收积累的主要因素。在盐地碱蓬中N、P、K、Ca、Mg、Na、Cl、Mn和Zn的含量均是生长前期较高,随着其生长老化逐渐降低,大穗结缕草、白茅与盐地碱蓬相比,Ca的含量前期低后期高,Na、Mn、Cu和Zn的季节变化不明显。参加盐地碱蓬系统生物循环的元素中,Cl和Na的比例最大,在大穗结缕草和白茅生态系统中比例较小;由于白茅被收割利用,一些元素从此生态系统中流失。     

Metal Accumulation Screening of the Río Tinto Flora (Huelva,Spain)

Río Tinto (Huelva, Spain) is located in one of the most important mining regions in the world. Its soils are characterized by their extreme acidity and elevated concentrations of heavy metals. Due to these characteristics, the Tinto ecosystem is considered unique and an ideal location to study biological adaptations to this type of habitat. Plant species that present these adaptations might be useful to mining and other metal pollution restoration programs. This study reports the results for the screening of Ca, Mg, Na, Mn, Fe, Ni, Cu, Zn, As, and Pb in aerial tissues of 97 plant species from the Tinto basin flora. In addition, plant–soil relationships were analyzed using the biological absorption coefficient (BAC) to detect the main plant adaptations in the Tinto flora. The species selected are representative of the biomass of the main dominant edaphophile and climatophile vegetation communities of the three river sections, forest, and subseral stages. Plant and soil elemental analyses were performed using inductively coupled plasma–mass spectrometry technique (ICP-MS). The results indicate that in general, Tinto flora shows a pattern of accumulation of the analyzed elements in aerial tissues which agrees with the nutritional requirements of vascular plants (macronutrients > micronutrients > indifferent or toxic elements). Among macronutrients, Ca seems to be an essential element in this habitat. This element accumulates in the aerial plant tissues. Basically, the Río Tinto flora is made of Fe, Cu, Zn, Ni, As, and Pb excluders, although some analyzed species of Erica, Quercus, Lavandula, Cistus, Genista, and Cytisus genera can be considered Mn accumulators. The results of this study make up a body of fundamental knowledge of the strategies used by plants to thrive in habitats with high concentrations of toxic heavy metals. This information is vital when it comes to planning a restoration program. Plants must be selected and used according to the requirements, always respecting the characteristics of the territory and facilitating the development of suitable vegetation.     

Metal Uptake and Distribution in Cultured Seedlings of Nerium oleander L. (Apocynaceae) from the Río Tinto (Huelva, Spain)

Nerium oleander L. (Apocynaceae) is a micro-nano phanerophyte that grows in the riverbanks of the Río Tinto basin (Southwest Iberian Peninsula). The waters and soils of the Río Tinto area are highly acidic and have high concentrations of heavy metals. In this environment, N. oleander naturally grows in both extreme acidic (EA) and less extreme acidic (LEA) water courses, excluding, and bioindicating certain metals. In this work, we compared and evaluated the accumulation preferences and capacities, the distribution and processes of biomineralization of metals (Fe, Cu, Zn, Mn, Mg, Ca) in the first stages of growth of EA and LEA oleanders by means of inductively coupled plasma–mass spectrometry, scanning electron microscopy, and energy dispersive X-ray analyzer analysis. Seeds from both environments were grown and treated with a self-made solution simulating the most extreme red waters from the Río Tinto. LEA plants drastically reduces the metal uptake at the beginning, but later reactivates the uptake reaching concentration values in the same range as the EA plants. The results showed high Mn, Zn and Mg concentrations, accumulation of Fe and Cu in plants from both environments, differing from the metal concentrations of field-grown oleanders. Iron bioformations with traces of other metals were present inside and over epidermal cells and inside vascular cells of stems and roots. They were absent of leaves. The accumulation properties of N. oleander in its early stages of development make it a species to take in consideration in phytoremediation processes but optimized conditions are needed to ensure enough biomass production.     

Alkali and alkaline earth metals in decomposing macrophytes in a wetland system

The background concentration of selected alkali and alkaline earth metals (sodium, potassium, calcium and magnesium) in some macrophytes was explored in the wetland system of Keoladeo National Park, Bharatpur, India. Changes in the concentration of these elements in the course of macrophyte decomposition were also studied. The species selected were Paspalum distichum, Paspalidium punctatum, Cyperus alopecuroides, Pseudoraphis spinescens, Ipomoea aquatica, Neptunia oleracea and Hydrilla verticillata, which dominate the aquatic vegetation of the Park. Litterbag decomposition experiments were carried out with nylon bags of two different mesh sizes (0.14 and 0.375 mm) in the laboratory and in the field. Among the macrophytes, Hydrilla was the fastest decaying species with the lowest half-life (12.65 days) and Paspalidium the slowest with the highest half-life (385.08 days). Overall, the grasses had low decay rate and high half-life. Background concentration of Na, K, Ca and Mg varied among the plant species. During decomposition and towards the end of the experiment, Na, K and Ca gradually declined whereas Mg increased. The variation was significant (ANOVA, P <0.05) among metals and macrophytes. Na showed no correlation with the weight loss of decomposing macrophytes in the field or in the laboratory tanks. In the field, the K concentration, in contrast with the observations in the tanks, was negatively correlated with the biomass and positively correlated with Ca content. Ca concentration in the biomass was negatively correlated with the weight of the remaining biomass, while Mg was positively correlated with the biomass in the litterbags.     

Alkali and alkaline earth metals in decomposing macrophytes in a wetland system

The foraging habitat selections of brown-eared pheasant (Crossoptilon mantchuricum) and the common pheasant (Phasianus colchicus) were studied in Huanglongshan Nature Reserve Shaanxi, China. Foraging habitat characteristics were measured on the basis of expected differences between species at 183 sites from November to December 2006 and January 2007. The results showed that both species selected foraging habitats with altitude (<1200 m), conifer forest, half sunny and half shady slope, sunny slope, density of trees (<5 individuals/100 m²), cover of shrub (>50%), visibility class (<10%) and distance to water source (<300 m). However, the brown-eared pheasant selected habitats with cover of trees (30–50%), middle or lower slope location, distance to edge of woods (<300 m) and human disturbance (<500 m), and the selection on density of shrub was not observed, compared to the selections on cover of trees (<30%), lower slope location, distance to edge of woods (<500 m) and human disturbance (<300 m), and density of shrub (>500 individuals/100 m²) for common pheasant. We also found that the common pheasant avoid predators by concealment whereas brown-eared pheasant evade predations by running away strategy.