Photosynthetic rate,needle longevity,and nutrient contents in <Emphasis Type="Italic">Picea glehnii</Emphasis> growing on strongly acidic volcanic ash soil in northern Japan

Picea glehnii Masters can grow in strongly acidic volcanic ash soil (pH 3.6) in northern Japan. We compared needle longevity, photosynthetic rate, and concentrations of elements in needles, in mature trees of P. glehnii growing in volcanic ash soil and in brown forest soil (pH 5.4). P. glehnii growing in volcanic ash soil showed suppressed photosynthetic rate and growth by the deficiency in nitrogen compared with its growth in brown forest soil. However, the younger needles of P. glehnii growing in volcanic ash soil maintained a high photosynthetic rate, as a result of large amounts of remobilized nitrogen from senesced needles. Needles of P. glehnii growing in volcanic ash soil did not show deficiencies in Ca, Mg, or K. Moreover, Al was at low levels in the needles, suggesting that P. glehnii was able to avoid Al toxicity by Al exclusion. P. glehnii thus exhibits great ability to adapt to an acidic environment.     

Nutrient dynamics and carbon partitioning in larch seedlings (Larix kaempferi) regenerated on serpentine soil in northern Japan

Japanese larch (Larix kaempferi) grows at a relatively high rate in northern Japan, even in serpentine soil. Serpentine soil has high concentrations of heavy metals (Ni, Cr), excessive Mg, and is nutrient deficient. These factors often suppress plant growth. We examined the mechanisms of Japanese larch’s tolerance to serpentine soil. We compared growth, photosynthetic capacity, and concentrations of elements in needles and roots between larch seedlings growing in serpentine soil and in nonserpentine (i.e., brown forest) soil. Dry mass of needles, stems, and branches were lower in seedlings grown on serpentine soil than in those grown on brown forest soil. There were lower concentrations of phosphorus and potassium in seedlings grown on serpentine soil than in those grown on brown forest soil. Seedlings growing on serpentine soil had lower Ni in plant organs. Our results suggest that larch seedlings grown on serpentine soil were able to exclude toxic elements. Moreover, the photosynthetic capacity and nitrogen concentration in needles was almost the same for seedlings grown in the two soil types. A wide range in growth was observed among individuals grown on both soil types. This may be regulated by nitrogen storage in the roots.     

Differences in growth characteristics and dynamics of elements absorbed in seedlings of three spruce species raised on serpentine soil in northern Japan

BACKGROUND AND AIMS: Serpentine soils are characterized by the presence of heavy metals (Ni and Cr) and excess Mg; these elements often suppress plant growth. Picea glehnii is nevertheless distributed widely on serpentine soils in northern Japan. Growth characteristics were compared among P. glehnii, Picea jezoensis (distributed in the same region) and Picea abies (planted for timber production), and concentrations of elements in various tissues over time and the amount of ectomycorrhizal infection in short roots were evaluated. METHODS: Seedlings of three spruce species were planted in two types of experimental plots, comprising serpentine soil and brown forest (non-serpentine) soil, and these seedlings were grown for 3 years. Growth, ectomycorrhizal infection of short roots, and elemental composition of tissues were examined. KEY RESULTS: The total dry mass of P. glehnii planted on serpentine soil was almost the same as on brown forest soil, and a large number of needles survived to reach later age classes. By contrast, growth of P. jezoensis and P. abies in serpentine soil was significantly less than in brown forest soil, and needle shedding was accelerated. Moreover, roots of seedlings of P. glehnii on serpentine soil were highly infected with ectomycorrhiza, and the concentration of Ni in needles and roots of P. glehnii was the lowest of the three species. CONCLUSIONS: Picea glehnii has a high ability to maintain a low concentration of Ni, and the ectomycorrhizal infection may have the positive effect of excluding Ni. As a result, P. glehnii is more tolerant than the other spruce species to serpentine soil conditions.     

Nickel tolerance of serpentine and non-serpentine Knautia arvensis plants as affected by arbuscular mycorrhizal symbiosis

Serpentine soils have naturally elevated concentrations of certain heavy metals, including nickel. This study addressed the role of plant origin (serpentine vs. non-serpentine) and symbiosis with arbuscular mycorrhizal fungi (AMF) in plant Ni tolerance. A semi-hydroponic experiment involving three levels of Ni and serpentine and non-serpentine AMF isolates and populations of a model plant species (Knautia arvensis) revealed considerable negative effects of elevated Ni availability on both plant and fungal performance. Plant growth response to Ni was independent of edaphic origin; however, higher Ni tolerance of serpentine plants was indicated by a smaller decline in the concentrations of photosynthetic pigments and restricted root-to-shoot Ni translocation. Serpentine plants also retained relatively more Mg in their roots, resulting in a higher shoot Ca/Mg ratio. AMF inoculation, especially with the non-serpentine isolate, further aggravated Ni toxicity to host plants. Therefore, AMF do not appear to be involved in Ni tolerance of serpentine K. arvensis plants.     

Effect of nitrogen load on growth and photosynthesis of seedlings of the hybrid larch F1 (Larix gmelinii var. japonica × L. kaempferi) grown on serpentine soil

We studied the growth and photosynthesis of the hybrid larch F₁ (Larix gmelinii var. japonica × L. kaempferi) grown on serpentine soil and the effects of soil N load, to determine the performance of this species as reforestation material in serpentine regions. We prepared 16 experimental plots (2 m × 4 m each), eight on serpentine and eight on brown forest soil, and planted one-year-old cutting seedlings of the hybrid larch F₁ in each plot, in May 2007. Ammonium sulfate was supplied to half of the plots of each soil type in 2008 and 2009, at a load of 47 kg N ha⁻¹ year⁻¹. Although the growth and photosynthetic capacity of hybrid larch F₁ seedlings in the serpentine soil were limited, the rate of growth in serpentine soil was greater than that of Sakhalin spruce (Picea glehnii) that is dominant species in serpentine regions. There was significant interaction between soil type and N load for the growth and photosynthetic parameters. The N load adversely affected growth and photosynthetic parameters in the serpentine soil, while improved them in brown forest soil. Although the growth rate of hybrid larch F₁ without N loading showed high potential as an afforestation species in serpentine region, increasing deposition of N might be a threat to the growth and photosynthesis of the hybrid larch F₁ in serpentine soil.     

Responses of two populations of an Iranian nickel-hyperaccumulating serpentine plant,Alyssum inflatum Nyar., to substrate Ca/Mg quotient and nickel

We selected two geographically close serpentine and non-serpentine populations of a Ni-hyperaccumulating plant (Alyssum inflatum) to investigate the influence of two common factors of serpentine soils: high Ni concentrations and low Ca/Mg quotients. Soils and plants were sampled from serpentine and non-serpentine substrates, and concentrations of Ca, Mg and Ni were measured. A hydroponic culture was used to compare growth and elemental composition responses of serpentine and non-serpentine plants to different Ca/Mg quotients and Ni concentrations in the nutrient solution. The Ca/Mg quotient for non-serpentine soils was 15 times higher than for serpentine soils, but there was no difference in the Ca/Mg quotient of plants from the two populations. In hydroponic culture, plants from both populations were able to survive at high Ca/Mg quotients. This result suggests that serpentine plants of A. inflatum do not necessarily need a substrate with a low Ca/Mg quotient for survival. Decreases in the Ca/Mg quotient in hydroponics decreased growth. The magnitude of this decrease was significantly greater in non-serpentine plants, suggesting a greater resistance of serpentine plants to low Ca/Mg quotients. Total Ni concentration in serpentine soils was 13 times higher than in non-serpentine soils, but ammonium nitrate-extractable concentrations of Ni in both soil types were similar. Ni concentrations in non-serpentine plants from their natural habitat were significantly lower than in serpentine plants, but there was no significant difference in Ni accumulation by plants of the two populations in hydroponic culture. However, increased concentrations of Ni in the hydroponic medium caused similar decreases in growth of both populations, indicating that Ni tolerance of the two populations was similar.     

Evidence of adaptive tolerance to nickel in isolates of Cenococcum geophilum from serpentine soils

Selection for metal-tolerant ecotypes of ectomycorrhizal (ECM) fungi has been reported in instances of metal contamination of soils as a result of human activities. However, no study has yet provided evidence that natural metalliferous soils, such as serpentine soils, can drive the evolution of metal tolerance in ECM fungi. We examined in vitro Ni tolerance in isolates of Cenococcum geophilum from serpentine and non-serpentine soils to assess whether isolates from serpentine soils exhibited patterns consistent with adaptation to elevated levels of Ni, a typical feature of serpentine. A second objective was to investigate the relationship between Ni tolerance and specific growth rates (μ) among isolates to increase our understanding of possible tolerance/growth trade-offs. Isolates from both soil types were screened for Ni tolerance by measuring biomass production in liquid media with increasing Ni concentrations, so that the effective concentration of Ni inhibiting fungal growth by 50% (EC₅₀) could be determined. Isolates of C. geophilum from serpentine soils exhibited significantly higher tolerance to Ni than non-serpentine isolates. The mean Ni EC₅₀ value for serpentine isolates (23.4 μg ml⁻¹) was approximately seven times higher than the estimated value for non-serpentine isolates (3.38 μg ml⁻¹). Although there was still a considerable variation in Ni sensitivity among the isolates, none of the serpentine isolates had EC₅₀ values for Ni within the range found for non-serpentine isolates. We found a negative correlation between EC₅₀ and μ values among isolates (r = −0.555). This trend, albeit only marginally significant (P = 0.06), indicates a potential trade-off between tolerance and growth, in agreement with selection against Ni tolerance in “normal” habitats. Overall, these results suggest that Ni tolerance arose among serpentine isolates of C. geophilum as an adaptive response to Ni exposure in serpentine soils. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The pH dependence of photosynthesis and elongation of Sphagnum squarrosum and S. girgensohnii in the Picea glehnii mire forest in Cape Ochiishi, north-eastern Japan

We investigated the pH dependence of the elongation of and photosynthesis by Sphagnum squarrosum and S. girgensohnii in a coastal Picea glehnii peat mire in Cape Ochiishi, north-eastern Japan. S. squarrosum grew in the acidic centre of the P. glehnii forest and showed the highest photosynthetic rate at pH = 3.8. S. girgensohnii grew at the margin of the P. glehnii forest and showed the maximum photosynthetic rate at pH = 7.2. Both species showed maximum growth at pH = 3.8. S. squarrosum elongated even at pH = 8.8, whereas S. girgensohnii stopped elongation at pH = 7.2. Although the pH dependence of photosynthesis by the Sphagnum species corresponded well to their distribution along the pH gradient from the centre to the margin of the P. glehnii forest, their short-term photosynthetic activity did not predict their long-term growth.     

Serpentine and Nonserpentine Achillea millefolium Accessions Differ in Serpentine Substrate Tolerance and Response to Organic and Inorganic Amendments

Subgrade serpentine substrates are exceptionally difficult to revegetate due to multiple limitations including low N, P, and K, low Ca:Mg molar ratios, high levels of heavy metals including Ni, Cr, and Co, low organic matter, low CEC, and low water holding capacity. To examine the influence of plant origin on the success of the revegetation of serpentine substrates, granite and serpentine accessions of Achillea millefolium were grown on subgrade serpentine substrate amended with yard waste compost, slow-release NPK fertilizer, and/or CaSO₄ · 2H₂O (gypsum). The goals of this study were to: (1) identify the substrate amendment combination that maximized establishment of A. millefolium on serpentine substrate, (2) compare seedling establishment, survival, and growth of the serpentine and granite A. millefolium accessions in order to determine if a serpentine edaphic ecotype of A. millefolium exists and if this ecotype is superior to the granite accession for the establishment of vegetation on serpentine substrate and (3) if a serpentine edaphic ecotype of A. millefolium does exist, what physiological features with respect to mineral nutrition convey a higher tolerance of serpentine for this ecotype than the nonserpentine ecotype. Seedling establishment, survival, and growth were greatest for A. millefolium when the subgrade serpentine substrate was amended with 30% (v/v) compost and 220 mg kg substrate⁻¹ each of N, P, and K. The serpentine A. millefolium accession displayed a greater tolerance of the subgrade serpentine substrate, serpentine topsoil, and the amended subgrade serpentine substrate than the granite accession. Higher capacity of the serpentine A. millefolium accession for selective Ca translocation from roots to the shoot resulted in a significantly higher shoot Ca:Mg molar ratio than the granite accession and appeared to be the most important physiological feature conveying greater tolerance of the serpentine accession for serpentine substrates.     

Serpentine ecotypic differentiation in a polyploid plant complex: shared tolerance to Mg and Ni stress among di- and tetraploid serpentine populations of <Emphasis Type="Italic">Knautia arvensis</Emphasis> (Dipsacaceae)

Background and aims

Serpentine soils impose limits on plant growth and survival and thus provide an ideal model for studying plant adaptation under environmental stress. Despite the increasing amount of data on serpentine ecotypic differentiation, no study has assessed the potential role of polyploidy. We tested for links between polyploidy and the response to serpentine stress in Knautia arvensis, a diploid-tetraploid, edaphically differentiated complex.

Methods

Variation in growth, biomass yield and tissue Mg and Ni accumulation in response to high Mg and Ni concentrations were experimentally tested using hydroponic cultivation of seedlings from eight populations of different ploidy and edaphic origin.

Results

Regardless of ploidy level, serpentine populations exhibited higher tolerance to both Mg and Ni stress than their non-serpentine counterparts, suggesting an adaptive character of these traits in K. arvensis. The effect of ploidy was rather weak and confined to a slightly better response of serpentine tetraploids to Mg stress and to higher biomass yields in tetraploids from both soil types.

Conclusions

The similar response of diploid and tetraploid serpentine populations to edaphic stress corresponded with their previously described genetic proximity. This suggests that serpentine tolerance might have been transmitted during the local autopolyploid origin of serpentine tetraploids.

     

Phytosociological study of thePicea jezoensis forests of the far east

Forest communities dominated byPicea jezoensis (Yezo spruce) are described from across their entire distributional range in eastern Asia, including the territories of the Russian Far East and Japan. A total of 476 relevés are used representing the following dominant types of spruce forests: pureP. jezoensis, mixedP. jezoensis andAbies sachalinensis, mixedP. jezoensis andAbies nephrolepis, and purePicea glehnii communities. The vegetation is classified into 11 associations, 2 community types, 6 subassociations, 25 variants and 8 subvariants. Nine associations, including theAsaro heterotropoidis-Abietetum sachalinensis, Weigelo middendorffianae-Piceetum jezoensis, Lysichito-Piceetum glehnii, Swido albae-Piceetum obovatae, Oplopanaco elati-Piceetum jezoensis, Philadelpho tenuifolii-Piceetum jezoensis, Vaccinio-Piceetum jezoensis, Rhododendro aurei-Piceetum jezoensis, andMoneseto uniflorae-Piceetum jezoensis, are described for the first time. The ecology and structure of all communities are described and their syntaxonomy discussed. The communities are placed in three alliances,Piceion jezoensis, Abieti nephrolepidis-Piceion jezoensis andPino pumilae-Piceion jezoensis, all. nov. All of the communities described are considered to belong to the orderAbieti-Piceetalia of the classVaccinio-Piceetea.     

Responses to Mg/Ca balance in an Iranian serpentine endemic plant, Cleome heratensis (Capparaceae) and a related non-serpentine species, C. foliolosa

A soil Ca/Mg quotient greater than unity is generally considered necessary for normal plant growth but some serpentine plants are adapted to much lower Ca/Mg quotients, resulting from a major cation imbalance in their substrata. In order to investigate the growth and tolerance responses of serpentine and non-serpentine species to varied Ca/Mg quotients, controlled nutrient solution experiments were performed using an a newly reported Iranian endemic serpentine plant, Cleome heratensis Bunge et Bien. Ex Boiss. and a related non-serpentine species Cleome foliolosa DC. and a Eurasian Ni-hyperaccumulating species Alyssum murale Waldst. and Kit. Seedlings were grown in modified Hoagland’s solutions with varying Ca and Mg concentrations (0.2–2.5 and 0.5–10 mM, respectively) in a fully factorial randomised block design. The yields of the two serpentine plants increased significantly as Mg concentrations in the nutrient solution were increased from 0.5 to 4 mM but decreased in the 10 mM Mg treatment. For C. foliolosa yields decreased significantly from 0.5 to 10 mM Mg, indicating the sensitivity of this non-serpentine plant, and the relative tolerance of the serpentine plants to extremely high levels of Mg. Shoot and root Mg and Ca concentrations in C. heratensis and A. murale were higher than those in C. foliolosa in the low and moderate Mg treatments, supporting the view that many serpentine plants have a relatively high requirement for Mg. Maximum Mg concentrations were found in the roots of C. heratensis. Yields of C. heratensis and A. murale did not change significantly as Ca levels in nutrient solution increased from 0.2 to 2.5 mM Ca, However the yield of C. foliolosa increased significantly from 0.2 to 1.5 mM Ca, indicating sensitivity in this non-serpentine plant and tolerance of the two serpentine plants to low levels of Ca correlated with tissue Ca concentrations, probably because of a greater ability for Ca uptake at low-Ca availability. Calcium deficiency in the low-Ca treatments could be a reason for reduced yield in the non-serpentine plants.     

Lignin-degrading ability of litter-decomposing basidiomycetes fromPicea forests of Hokkaido

The frequency of occurrence of the litter-decomposing basidiomycetes ofPicea abies andP. glehnii forest floors in Hokkaido was investigated. In both theP. abies andP. glehnii forest plots (each 10 m×10 m), litter-decomposing basidiomycetes of the generaCollybia andMycena were frequently observed. Species composition, frequency of occurrence, and basidioma numbers of each species were different between the two forest plots, but several species were common to both. Seven species isolated from theP. glehnii forest plot (C. acervata, C. pinastris, Marasmius pallidocephalus, Ma. wettsteinii, My. aurantiidisca, My. clavicularis, Mycena sp. 1) and four species from theP. abies forest plot (C. pinastris, My. alphitophora (=My. osmundicola), Mycena sp. 1,My. vulgaris) were tested for their ability to degrade lignin by a simple plate test for extracellular phenoloxidases and by measuring Klason lignin loss from needle litter of spruce. All the strains of the litter-decomposing fungi tested showed positive reactions on the plate test. Lignin contained in the needle litter was degraded by all strains tested (onlyMy. alphitophora was not tested), and rates varied from 9% to 40% over a two-month period in vitro. Seven species with ligninolytic ability in theP. glehnii forest plot and four such species in theP. abies forest plot were found respectively in 77% and 60% of the 100 subplots in each plot. The results of this study suggest that lignin decomposition of needle litter by litter-decomposing basidiomycetes in the forest floor is a common event in the studiedPicea forests of Hokkaido and that the diversity of the ligninolytic activity among the species or strains may cause spatial heterogeneity of litter decomposition in thePicea forest floor.     

Effects of calcium on nickel tolerance and accumulation in Alyssum species and cabbage grown in nutrient solution

Nickel (Ni) phytoextraction using hyperaccumulator plant species to accumulate Ni from mineralized and contaminated soils rich in Ni is undergoing commercial development. Serpentinite derived soils have a very low ratio of Ca/Mg among soils due the nature of the parent rock. In crop plants, soil Ca reduces Ni uptake and phytotoxicity, so it is possible that the low Ca of serpentine soils could limit hyperaccumulator plant tolerance of serpentine soils used for commercial phytomining. In this study, we investigated the effects of varied Ca concentration in the presence of high Mg characteristic of serpentine soils on Ni uptake and tolerance by serpentine-endemic species Alyssum murale Waldst. et Kit. and A. pintodasilvae T.R. Dudley in comparison with cabbage (Brassica oleracea L. var. capita) in a nutrient solution study. The levels of Ca and Mg used were based on serpentine and normal soils, and Ni was based on achieving over 1% Ni in Alyssum shoots in preliminary tests. Varied solution concentrations of Ni (31.6–1,000 μM for Alyssum, 1.0–10 μM for cabbage) and Ca (0.128–5 mM) were used in a factorial experimental design; 2 mM Mg was used to mimic serpentine soils. Alyssum spp. showed much greater tolerance to high Ni, high Mg, and low Ca solution concentrations than cabbage. For Alyssum spp., Ni induced phytotoxicity was only apparent at 1,000 μM Ni with relatively low and high Ca/Mg quotient. In the 1,000 μM Ni treatment, shoot Ni concentrations ranged from 8.18 to 22.8 g kg^?1 for A. murale and 7.60 to 16.0 g kg^?1 for A. pintodasilvae. Normal solution Ca concentrations (0.8–2 mM) gave the best yield across all Ni treatments for the Alyssum species tested. It was clear that solution Ca levels affected shoot Ni concentration, shoot yield and Ni translocation from root to shoot, but the relation was non-linear, increasing with increasing Ca up to 2 mM Ca, then declining at the highest Ca. Our results indicate that Ca addition to high Mg serpentine soils with very low Ca/Mg ratio may reduce Ni phytotoxicity and improve annual Ni phytoextraction by Alyssum hyperaccumulator species. Removal of shoot biomass in phytomining will require Ca application to maintain full yield potential.     

Effects of life history strategies and tree competition on species coexistence in a sub-boreal coniferous forest of Japan

We examined the effects of different life history strategies and tree competition on species coexistence in a northern coniferous forest. We investigated the growth and demography of trees with stems ≥1 cm dbh in a 2-ha study plot in the Taisetsu Mountains of northern Japan. Three species, Abies sachalinensis, Picea jezoensis, and Picea glehnii, were found to be dominant in the forest. A. sachalinensis was the most dominant species in the understory, while the two Picea spp. were more abundant in the larger dbh size classes. The turnover rate of A. sachalinensis was about twice that of the Picea spp. The relative growth rate of understory trees in each species did not differ between different canopy conditions (closed canopy or canopy gap). The competitive advantage between A. sachalinensis and P. glehnii switched as they grew from understory (A. sachalinensis superior competitor) to canopy trees (P. glehnii superior competitor). Meanwhile, A. sachalinensis and P. jezoensis exhibited different environmental preferences. We propose that reversal in competitive superiority between different growth stages and trade-off between longevity and turnover are more important factors to promote their coexistence than regeneration niche differentiation related to canopy gaps in this sub-boreal coniferous forest.     

Alcuni aspetti del metabolismo di piante coltivate sia su un terreno serpentinoso sia in presenza di nichel

Abstract

Effects of serpentine and Ni on some aspects of plant metabolism. — Results are here reported of a series of experiments on the metabolism of plants grown on a serpentine soil and in sand and water cultures with the addition of Ni. Variations in the content of citric and malic acid, chlorophylls, P, Ni, Fe (total and HCl soluble), Mn and Cu have been followed during plant growth in the leaves and roots. In Avena and Phaseolus the citric acid content greatly increases in both treatments (serpentine and Ni); the chlorophylls (a+b) markedly decrease; HCl sol. Fe is always reduced, particularly in the serpentine plants, total Fe accumulates in the roots in both treatments. The P content is particularly high in the Ni-treated plants, whilst on serpentine oats are always P-deficient, showing also a lower Mn and Cu content than plants grown in water cultures plus Ni. The relationships between citrate accumulation and scarce Fe translocation are discussed.     

Genetic structure of Sakhalin spruce (<Emphasis Type="Italic">Picea glehnii</Emphasis>) in northern Japan and adjacent regions revealed by nuclear microsatellites and mitochondrial gene sequences

The genetic structure of Sakhalin spruce (Picea glehnii) was studied across the natural range of the species, including two small isolated populations in south Sakhalin and Hayachine, by using six microsatellite loci and maternally inherited mitochondrial gene sequences. We also analyzed P. jezoensis, a sympatric spruce in the range. Genetic diversity of P. glehnii was higher in central Hokkaido and the lowest in the Hayachine. Bayesian clustering and principal coordinate analysis by using the microsatellites indicated that the Hayachine was clearly distinct from other populations, implying that it had undergone strong genetic drift since the last glacial period. P. glehnii harbored four mitochondrial haplotypes, two of which were shared with P. jezoensis. One of the two was observed without geographical concentration, suggesting its derivation from ancestral polymorphism. Another was observed in south Sakhalin and in P. jezoensis across Sakhalin. The Bayesian clustering—by using four microsatellite loci, including P. jezoensis populations—indicated unambiguous species delimitation, but with possible admixture of P. jezoensis genes into P. glehnii in south Sakhalin, where P. glehnii is abundantly overwhelmed by P. jezoensis; this might explain the occurrence of introgression of the haplotype of P. jezoensis into P. glehnii.     

The effects of metal ions on the root surface phosphatase activity of grasses differing in tolerance to serpentine soil

Summary Six grass species which differed in ability to grow on serpentine soils were assayed for root surface acid phosphatase activity in solutions of Ca, Mg, Ni, Cr III, Cr VI, and Zn at various concentrations. The root surface phosphatases of relatively serpentine tolerant species (Festuca rubra, Festuca pratensis and Holcus lanatus) were unaffected by the external Ca concentration whereas Ca increased the activity of root surface phosphatase in species relatively intolerant to serpentine soil conditions (Phleum pratense vars Scots and S51 and Lolium perenne). There were no differences shown between a tolerant and an intolerant grass in their responses to Mg, Ni, Cr III, Cr VI or Zn. re]19760611     

Length variation in the internal transcribed spacers of ribosomal DNA in Picea abies and related species

The structure and variation of nuclear ribosomal DNA (rDNA) units of Picea abies, (L.) Karst. was studied by restriction mapping and Southern hybridization. Conspicuous length variation was found in the internal transcribed spacer (ITS) region of P. abies, although the length of this region is highly conserved both within and among most of the plant species. Two types of ITS variants (A and B), displaying a size difference of 0.5 kb in the ITS2 region, were present within individuals of P. abies from Sweden, Central Europe and Siberia. A preliminary survey of 14 additional Eurasian and North American species of Picea suggested that length variation in the ITS region is widespread in this genus. Alltogether three length variants (A, B and C) were identified. Within individuals of eight Picea species, two length variants were present within the genome (combinations of A and B variants in P. glehnii, P. maximowiczii, P. omorika, P. polita and P. sitchensis and variants B and C in P. jezoensis, P. likiangensis and P. spinulosa). Within individuals from five species, however only one rDNA variant was present in their genome (variant A in P. aurantiaca, P. engelmannii, P. glauca, P. koraiensis and P. koyamai; variant B in P. bicolor). The ITS length variation will be useful as a molecular marker in evolutionary studies of the Picea species complex, whose phylogeny is controversial. The presence of intraindividual variation in, and shared polymorphism of the, ITS length variants raises questions about the occurrence of interspecific hybridization during the evolutionary history of Picea.     

Stand structure and growth patterns of understorey trees in a coniferous forest,Taisetsuzan National Park,northern Japan

Stand structure was studied with special reference to growth and mortality patterns of sapling and understorey trees in a coniferousPicea jezoensis andAbies sachalinensis forest in Taisetsuzan National Park, Hokkaido, northern Japan.Picea jezoensis was dominant in the basal area, whileA. sachalinensis was abundant in large numbers in the canopy. Estimated mortalities increased significantly with diameter at breast height (DBH) for bothP. jezoensis andA. sachalinensis in the canopy, but the tendency was different between the two species.Picea jezoensis had a lower mortality rate thanA. sachalinensis, especially at small DBH classes. The spatial distribution of understorey individuals ofA. sachalinensis did not show any significant correlation with the spatial distribution of canopy gaps, but that ofP. jezoensis showed a significant correlation.Abies sachalinensis can grow higher thanP. jezoensis under suppressed conditions; whileP. jezoensis requires canopy gaps for steady height growth. This growth pattern leads to a different waiting height in the understorey (≥2 m in height and 10 cm in diameter at breast height).Abies sachalinensis waited for an improvement in light conditions at higher strata (max. 7 m), whileP. jezoensis waited at lower strata (max. 3 m). The estimated mortality of understoreyA. sachalinensis increased with size, while that of understoreyP. jezoensis decreased. Therefore,P. jezoensis gives priority to survival whileA. sachalinensis gives priority to understorey growth. The difference in the ‘waiting pattern’ between the two species in the understorey was considered a significant feature for the canopy recruitment process ofP. jezoensis andA. sachalinensis.