Effects of acidity of the water culture solution on uptake of nutrients by the root of Japanese cedar (Cryptomeria japonica) and Japanese cypress (Chamaecyparis obtusa)

The condition around coniferous trees in the soil is becoming gradually acidic when acid rain falls continuously. Nutrient uptake by the roots of coniferous trees could be affected in such environmental change of root zone. The experiments of water culture of coniferous seedlings in modified systems were carried out using (2-and, 3-year-old) of Japanese cedar(Cryptomeria japonica) and, Japanese cypress(Chamaecyparis obtusa) that are the typical Japanese forest trees. Nine major nutrients such as Na⁺, NH₄ ⁺, K⁺, Ca²⁺, Mg²⁺, Cl^?, NO₃ ^?, PO₄ ^3?, and SO₄ ^2?, were given in the water culture solution and growth of trees was observed for two years. The aspects of nutrient uptake by these seedlings and the effects of acidity in culture solution were observed. The following results were obtained. 1) Japanese cedar of 50% and Japanese cypress of 30 % in tested seedlings could live for two years. 2) All Japanese cedar and cypress that started in the strong acidic condition ( pH=3.0) were dead within three months. 3) The minimum pH value in the acidic condition is estimated as 3.2 for these coniferous seedlings, and it means that they can live at least for two years in this condition. 4) The seasonal pattern of the uptake of nitrogen nutrient by Japanese cedar was determined.     

Soil Solution Chemistry in Forests with Granite Bedrock in Japan

Soil solutions were taken from three forest areas with granite bedrock in Japan (Abukuma, Tateyama and Hiroshima) to investigate pH values, forms of Al and the molar BC/Al ratios. In each area, 10 sites were chosen for study. At each site, a target tree was selected, and two soil solution samples were taken from 10 cm depth at points 10 cm and 100 cm from the trunk of the tree to evaluate the effects of stemflow and throughfall on soil solution chemistry. Values of pH of samples taken 10 cm from the trunks (referred to as S samples) and 100 cm from the trunks (referred to as T samples) ranged from 3.66 to 6.52 and from 4.55 to 6.48, respectively. For Japanese cedar (Cryptomeria japonica) and Japanese cypress (Chamaecyparis obtusa) trees, S samples showed lower pH than T samples, whereas the inverse relation was observed for broadleaf trees. In the Abukuma and Tateyama areas, the concentrations of monomeric Al (Al_m) were mostly below 30 µmol L^?1. In the Hiroshima area, however, extremely high Al_m concentrations (up to 293 µmol L^?1) were observed at some sites. The molar ratio of BC (= Ca + Mg + K) to inorganic monomeric Al was higher than 1 for all samples, except for an S sample from the Hiroshima area having a ratio of 0.72.     

Calcium concentration in leaf litter alters the community composition of soil invertebrates in warm-temperate forests

Many studies have shown the effects of aboveground plant species on soil organisms due to differences in litter quality. However, the calcium concentration in soil has received less attention as a controlling factor of soil invertebrate communities, even though it is an essential element for many animals, especially crustaceans. Litter of Japanese cedar (Cryptomeria japonica) plantations, which account for 19% of the forested area in Japan, has a higher calcium concentration compared to other taxa such as broad-leaved trees. We predicted that C. japonica plantations affect soil invertebrates by altering calcium availability. We compared soil properties including exchangeable calcium concentration and soil invertebrate communities between C. japonica plantations and natural broad-leaved forests. Exchangeable calcium was significantly higher in soil from cedar plantations than in that from broad-leaved forests. The invertebrate community composition differed between the two forest types and was best explained by the exchangeable calcium concentration. In particular, two major taxa of soil crustaceans (Talitridae and Ligidium japonicum) were found only in cedar plantations. Our results suggest that calcium concentrations in soil are altered in C. japonica plantations and that this affects soil invertebrate communities.     

Faecal Contamination Indicators in Irrigation Water: Evaluation of a Standard Method and Comparison with an Alternative System

Japanese fir (Abies firma) forests on the urban-facing side ofMt. Oyama, eastern Japan are frequently exposed to acidic depositions. These forests have been declining more severely than those on the mountain-facing side. Chlorophyll, N, Mg, K, Ca, P and Al contents were determined for current, one- and two-year-old needles collected from the crown surfaces of Japanese fir tree forming the forest canopy (ca. 30 m height) on both sides of Mt. Oyama. Needle dry mass per needle area on the urban-facing side was significantly smaller than that on the mountain-facing sides for each needle age class. This result suggests that the development of internal tissues of fir needles on the urban-facing side is defective. N and Chl contents per needle area on the urban-facing side were smaller than those on the mountain-facing sides, indicating that photosynthetic activity per needle area is suppressed in the needles from the urban-facing side. For each needle age class, both area- and mass-based Mg contents were smaller on the urban-facing side than on the mountain-facing side, but mass-based Al contents were greater on the urban-facing side. These results suggest that acidic depositions cause nutritional disorders, which, in turn, leads to decreased needle productivity in the fir trees on the urban-facing side.     

Microbial Immobilization and Plant Uptake of Different N Forms in Three Forest Types in Shikoku District, Southern Japan

Soil microbial immobilization and plant uptake of N were evaluated for three forest types in Kochi, Shikoku district. During 196-d laboratory incubation, soil NO₃-N production in the Hinoki cypress forest was negligible for the initial 40 d and then rapidly increased, whereas NO₃-N production was rapid from the beginning in Japanese cedar and deciduous hardwood forests. Microbial immobilization of the labeled ¹⁵N decreased in the order of NH₄-N>glycine-N>NO₃-N. The ¹⁵N immobilization was higher for soil in the Hinoki cypress forest than other two soils. The delayed NO₃-N production in the Hinoki cypress forest was likely related with low availability of NH₄-N due to NH₄-N immobilization and substantial NO₃-N immobilization. In the field experiment, ¹⁵N uptake by roots decreased in the order of NH₄-N>NO₃-N>glycine-N. The absorption of the labeled ¹³C suggested direct uptake of organic N. The preference of N forms by root uptake was not different among forest types. Trees in three forest types can absorb inorganic and organic forms of N, suggesting trees absorb the N form that is the most abundant in the soil.     

Effect of simulated acid rain on the growth of Japanese conifers grown with or without fertilizer

Three-year old cuttings of Japanese cedar (Cryptomeria japonica), Japanese cypress (Chamaecyparis obtusa) and Sawara cypress (Chamaecyparis pisifera) were grown in pots with andosol and were exposed to simulated acid rain (SAR) at pH 2.0, 3.0, and 4.0 for 23 months. Total precipitation was 2460, 3960, or 5450 mm and SAR contained sulfuric, nitric and chloric acid at equivalent ratio of 5∶2∶3. Deionized water of pH 5.6 was a control. Exposure to SAR at pH 2.0 induced visible foliar injuries, but not any visible symptoms at pH 3.0 or higher. Total dry weights of 3 conifer cuttings grown with fertilizer were about two fold of those in plants grown without fertilizer and they reduced significantly by the exposure to SAR at pH 2.0. However, Cryptomeria japonica without fertilizer increased dry weights even though plants developed reddish-brown necrosis in large parts of tops. These 3 coniferous cuttings did not show any significant growth reduction at pH 3.0 and 4.0. Soil pH after receiving 5450 mm of SAR at pH 2.0 was 4.0 and molar ratio of (K+Ca+Mg)/Al in water and 1M ammonium acetate soluble fraction of the soil was about 0.3 and 0.4. respectively. However, dry weight of root in plants grown without fertilizer did not decrease. This suggested that growth reduction in plants fertilized and exposed to pH 2.0 was due to a reduction in photosynthetic organs associated with visible injuries, but not direct linkage with root growth inhibition due to soil acidification stress.     

Diversity in tree species in Southeastern Ohio Betula nigra L. Communities

Quantitative data were obtained for arboreal species within 50 lowland forests in southeastern Ohio. Thirty-seven communities were dominated by Betula nigra L. and 13 were dominated by Acer saccharinum L. The acidic soils collected from B. nigra communities contained toxic concentrations of exchangeable Al and low concentrations of Ca and Mg. Tree species diversity (Shannon-Weaver index) and species equitability were inversely related to high concentrations of exchangeable Al and H and directly related to high concentrations of exchangeable Ca and Mg and an increase in soil pH.     

Changes in soil organic carbon and nitrogen in an area of Andisol following afforestation with Japanese cedar and Hinoki cypress

Abstract

To determine the rates of increase in C and N stocks in the soil and organic layers following afforestation in Andisols, we measured C and N densities in the organic and soil layers at depths of 0–5, 5–15 and 15–30?cm, together with a chronosequence analysis of 4-year-old, 14-year-old and 23-year-old Japanese cedar (Cryptomeria japonica) and 4-year-old, 12-year-old and 25-year-old Hinoki cypress (Chamaecyparis obtusa) plantations. The short-term changes in C and N were confirmed by repeated sampling 5?years after the first sampling. Tree growth, biomass accumulation and organic layers were much greater in Japanese cedar than in Hinoki cypress plantations. Soil C density (kg?m^?3) increased and bulk density decreased with stand age in the surface layer (0–5?cm). The average soil C accumulation rate was 22.9?g?C?m^?2?year^?1 for Japanese cedar and 21.1?g?C?m^?2?year^?1 for Hinoki cypress. Repeated sampling showed that the rate of increase in C in the surface soil was relatively slow in young stands and that soil C density (kg?m^?3) in the subsurface soil did not change over a 5-year period. Although N accumulated in the tree biomass and organic layers, the soil N density (kg?m^?3) did not change after afforestation. Although the andic properties of the soil and differences in the planted species did not influence the rate of increase in soil C, soil C density was expected to increase to a concentration greater than 80?g?kg^?1, possibly because of the large C accumulation capacity of Andisols.     

Response of Physic Nut Trees to Liming of Acidic Soils

The physic nut tree (Jatropha curcas) is an oilseed species with potential for biodiesel production. We evaluated the effect of soil acidity indices on nutrient uptake for optimal growth in physic nut plants grown on acidic soils under greenhouse conditions. Two soils were used in the experiment. Maximum growth was obtained with the application of 1.05 g lime kg^-1 for both soils. Maximum growth of the physic nut plants occurred under the following conditions: pH of water = 6.1, calcium (Ca²⁺) = 17.0 mmol_c kg^?1, magnesium (Mg²⁺) = 5.7 mmol_c kg^?1, acidity saturation = 10.3%, base saturation = 52.3%, Ca saturation = 36.0%, Mg saturation = 12.0% and potassium (K) saturation = 3.8%. Furthermore, the nitrogen (N) requirement of physic nut trees was shown to be high, and to a lesser degree, Ca and Mg requirements were also high, suggesting that liming is very important in crop cultivation of this species.     

N2-fixation and growth promotion in cedar colonized by an endophytic strain of Paenibacillus polymyxa

Inoculation of western red cedar with Paenibacillus polymyxa P2b-2R, an endophytic diazotroph of a pine, was previously shown to result in biological nitrogen fixation (BNF) in seedlings grown under N-limited conditions, but biomass accumulation was reduced after a 9-month growth period. To determine if the seedling growth reduction was temporary, we inoculated cedar seed with strain P2b-2R and grew seedlings for up to 13 months in a N-limited soil mix containing 0.7 mM of available N labeled as Ca(¹⁵NO₃)₂. P2b-2R developed a persistent endophytic population comprising 10²–10⁶?cfu g^?1 plant tissue inside pine roots, stems, and needles. At the end of the growth period, P2b-2R had reduced ¹⁵N foliar N abundance by 36 % and increased shoot biomass by 46 % compared to controls. Our results indicate that inoculated seedlings derived 36 % of foliar N from the atmosphere and suggest that BNF by P. polymyxa can significantly enhance growth of cedar in a N-limited soil if seedlings are grown for a sufficient amount of time. These findings support the hypothesis that endophytic diazotrophs may facilitate regeneration and growth of western red cedar at N-poor sites.     

Nutritional status of declining spruce (Picea abies (L.) Karst.): Effect of soil organic matter turnover rate

Foliar analysis was undertaken in two plots of Picea abies (L.) Karst., located in a watershed of Haute Ardenne, Belgium, in order to estimate the decline of the trees. Apart from a general Mg deficiency, the concentrations of the needles were in the same range as those determined in other European stands. Comparisons between healthy and declining trees within each plot revealed a general pattern of decline similar to that observed elsewhere in Western Europe. This was shown as lower Ca, Mg, Zn concentrations and water content and higher N and P concentrations of the needles collected from declining trees. It is concluded that this decline could be due to N over fertilization by the atmospheric deposition. The difference of decline between the two plots was attributed to the turnover rate of the soil organic layer which was less intensive in the most damaged plot.     

The Plant Community of Nanjido, a Representative Nonsanitary Landfill in South Korea: Implications for Restoration Alternatives

Vegetation and soil analyses of the slopes of the Nanjido, a nonsanitary landfill in South Korea, were conducted to investigate the colonization status of plant communities, and to suggest restoration alternatives by comparing the vegetation of the landfill and the nearby forests. The vegetation of the Nanjido landfill and the control sites was surveyed by using 10 ×: 10 m quadrats. The soils were analyzed for pH, electrical conductivity, organic matter content, Total-N, P, K, Ca, Mg, sand, silt, and clay. Canonical correspondence analysis (CCA) was performed by using the extent of cover for all the recorded species, and the physical and chemical variables of soil. Salix babylonica, Platanus orientalis, Rosa multiflora, Prunus persica,Albizzia julibrissin, Indigofera pseudo-tinctoria, Robinia pseudoacacia, Amorpha fruticosa, Ailanthus altissima, Forsythia koreana, and Paulownia tomentosa were the commonly found tree species.Quercus mongolica, considered to be the natural late successional species of temperate South Korea, was recorded at the Nanjido landfill. Levels of pH, the electrical conductivity and concentrations of P, Ca, and Mg in landfill soils were significantly higher than the forest control site soils (P < 0.05). In CCA ordination space, landfill quadrats clustered in less acidic soils, rich in Ca and Mg, while forest control site quadrats clustered in acidic, low P soils. This study found several indications that it is possible for a nonsanitary landfill to support succession to typical and natural forests. In addition, the landfill slope vegetation could function as a biological source for the restoration of the other landfill areas that remain barren, if planned efforts are made for conservation and rehabilitation.     

Impacts of Plant Community Changes on Soil Carbon Contents in Northeastern Illinois

Land-cover changes not only affect regional climates through alteration in surface energy and water balance, but also affect key ecological processes, such as carbon (C) cycling and sequestration in plant ecosystems. The object of this study was to investigate the effects of land-cover changes on the distribution of soil organic carbon (SOC) contents under four plant community types (deciduous forests, pine forests, mixed pine-deciduous forests, and prairies) in northeastern Illinois, USA. Soil samples were collected from incremental soil depths (0–10, 10–20, 20–30, and 30–50 cm) under the studied plant communities. The results showed that SOC concentration decreased with increases of soil depth in the studied forests and prairies. No significant differences of SOC concentrations were found at the upper soil layers (0–10 cm) among the four plant types. However, SOC concentrations were statistically higher at the lower soil depth (30–40 cm) in prairies than in other three forest types. The SOC storage (0–40 cm soil depth) was reduced in an order prairies (250.6) > mixed pine-deciduous forests (240.7) > pine forests (190.1) > deciduous forests (163.4 Mg/ha). The characteristics of relative short life cycle, restively high turnover rate of roots, and large partition of photosynthetic production allocated to belowground were likely attributed to the higher accumulation of C in soils in tallgrass prairies than in forests. Our data indicated the conversion of native tallgrass prairies to pure forest plantations resulted in a considerable decline of SOC storage. Results suggest that land-cover changes have a significant impact on SOC storage and sequestration in plant ecosystems.     

Relationships between symptoms expressed by Norway spruce and foliar and soil elemental status

Surveys conducted from 1987 to 1990 of Norway spruce [Picea abies(L.) Karst.] within 12 plantations across 4 northeastern states revealed symptoms of crown discoloration and defoliation on a site-specific basis. Foliar N. K. and Ca concentrations of most of the sampled trees were above deficiency ranges, while foliar Mg concentrations of most of the symptomatic trees were below the deficiency range within the plantations. Soil pH, exchangeable Mg, K, Ca, and their corresponding percent saturations in soils were lower, while soil Al concentrations were higher for most of the symptomatic trees in comparison to the healthy trees. Foliar concentrations of Mg, Ca, K, P, Al, Mn, Pb, and Zn were positively correlated with concentrations of corresponding soil elements. Knowledge of nutrient deficiency ranges may help diagnose foliar symptoms, but their exclusive use may overly simplify relationships between foliar symptoms and foliar elements. Principal component regression analysis of the data provided assessment of interactions and balances among foliar elements, and among soil elements and their possible influences on crown symptoms. Crown symptoms were not only associated with concentrations of individual elements of foliage and soils, but also associated with interactions and balances between these elements. The influences of individual soil elements on discoloration and defoliation may depend upon other elements in soils. Soil Al may induce crown discoloration and defoliation by interfering with Mg, Ca, and K uptake in acidic soils.     

上海松柏古树生长与土壤肥力因子的关系

【目的】松柏古树是上海古树的重要组成部分。土壤肥力状况影响松柏古树的生长,研究不同生长点的土壤性质,并分析其对松柏古树生长的影响,为松柏古树的土壤管理提供理论依据。【方法】以上海地区不同生长点的松柏古树为试验对象,测定了土壤的理化性质 (土壤容重、通气孔隙度、pH值、EC值) 和养分 (有机质、水解氮、有效磷、速效钾及钙、镁、铁、锌),对土壤肥力进行了评价,并进一步分析了土壤对松柏古树生长的影响。【结果】上海松柏古树的土壤pH值为中性偏碱性,可溶性盐分整体较适中,有机质、水解氮的供应水平较高,速效钾供应充足,有效磷供应水平偏低,土壤中的钙、镁、铁、锌含量较为丰富,不存在中毒现象。松柏古树的生长受根系的菌根侵染率影响,与根系的菌根侵染率呈显著正相关,侵染率越高,生长越好;松柏古树的生长与土壤的理化性质有关,与土壤通气孔隙度呈显著正相关、与容重呈显著负相关,通气孔隙度越大,容重越小,生长越好。【结论】目前上海松柏古树的土壤容重偏大,通气孔隙度小,存在通气不良现象。在实际保护松柏古树过程中,宜采取提高菌根侵染率、提高土壤孔隙度、提供充足的有机质和降低土壤容重等措施。     

Chemical Characteristics in Stemflow of Japanese Cedar in Japan

To clarify the characteristics in stemflow of Japanese cedar (Cryptomeria japonica), we conducted the annual and extensive observation. We examined the chemistry of bulk and wet deposition, throughfall and stemflow at 26 forested sites in June and September 1998. The each sampling site was broadly distributed in all over the Japanese archipelago. The stemflow pH of Japanese cedar was significantly lower (p<0.01) than precipitation and stemflow of broad-leaved species in both months. There were significant anion deficits in stemflow of Japanese cedar, suggesting that organic anions derived from plant sources play an important role in the stemflow acidity. Our results suggested that the strong stemflow acidity in Japanese cedar was derived from an internal biological characteristic rather than influences of external acidic deposition.     

Copper Complexing Capacity of Throughfall and its Environmental Effect

Copper complexing capacity (CuCC) and conditional stability constants (K′) of the complexes were analyzed for throughfall collected in Japanese cypress (Chamaecyparis obtusa), Japanese cedar (Cryptomeria japonica), Japanese red pine (Pinus densiflora), and bamboo-leafed oak (Quercus myrsinaefolia) groves (soil: light-colored Andosol) located in a suburban area of Japan (Tsukuba, Ibaraki). The method was based on the titration of throughfall samples with standard Cu²⁺ solution using a Cu²⁺-selective electrode, followed by data analysis using the van den Berg-Ruzic plot (1:1-type complexes were assumed). CuCCs (μM) obtained were in the order: C. obtusa (7.1± 5.1) ≤ C. japonica (9.6± 5.6) < P. densiflora (15.9± 16.4) < Q. myrsinaefolia (29.3± 23.9). In addition, ratios of CuCC/DOC (μmol mg^?1 C) were in the order: C. obtusa (0.42± 0.26) ? C. japonica (0.42± 0.22) ? P. densiflora (0.55± 0.38) ? Q. myrsinaefolia (2.0± 1.3), and the ratios in the throughfall of Q. myrsinaefolia were about 4 times higher than those in the throughfall of other tree species. On the other hand, log K′ was almost the same for all tree species (about 5.5). CuCC and also CuCC/DOC increased in spring and autumn, and decreased in summer and winter, indicating that organic matter with metal complexing capacity, released from trees, changed seasonally not only in quantity but also in quality. Since throughfall accelerated the leaching of metals from grove soil and artificial material (e.g. alloy) placed in the groves, it may be involved in the behavior of metals in the plant-soil ecosystem.     

Methane uptake and nitrous oxide emission in Japanese forest soils and their relationship to soil and vegetation types

Abstract

To determine the means and variations in CH₄ uptake and N₂O emission in the dominant soil and vegetation types to enable estimation of annual gases fluxes in the forest land of Japan, we measured monthly fluxes of both gases using a closed-chamber technique at 26 sites throughout Japan over 2 years. No clear seasonal changes in CH₄ uptake rates were observed at most sites. N₂O emission was mostly low throughout the year, but was higher in summer at most sites. The annual mean rates of CH₄ uptake and N₂O emission (all sites combined) were 66 (2.9–175) µg CH₄-C m^?2 h^?1 and 1.88 (0.17–12.5) µg N₂O-N m^?2 h^?1, respectively. Annual changes in these fluxes over the 2 years were small. Significant differences in CH₄ uptake were found among soil types (P < 0.05). The mean CH₄ uptake rates (µg CH₄-C m^?2 h^?1) were as follows: Black soil (95 ± 39, mean ± standard deviation [SD]) > Brown forest soil (60 ± 27) ≥ other soils (20 ± 24). N₂O emission rates differed significantly among vegetation types (P < 0.05). The mean N₂O emission rates (µg N₂O-N m^?2 h^?1) were as follows: Japanese cedar (4.0 ± 2.3) ≥ Japanese cypress (2.6 ± 3.4) > hardwoods (0.8 ± 2.2) = other conifers (0.7 ± 1.4). The CH₄ uptake rates in Japanese temperate forests were relatively higher than those in Europe and the USA (11–43 µg CH₄-C m^?2 h^?1), and the N₂O emission rates in Japan were lower than those reported for temperate forests (0.23–252 µg N₂O-N m^?2 h^?1). Using land area data of vegetation cover and soil distribution, the amount of annual CH₄ uptake and N₂O emission in the Japanese forest land was estimated to be 124 Gg CH₄-C year^?1 with 39% uncertainty and 3.3 Gg N₂O-N year^?1 with 76% uncertainty, respectively.     

Chemical Characterization of Cow Manure and Poultry Manure after Composting with Privet and Cypress Residues

ABSTRACT

Investigating available nutrients and non-essential elements in manures is important for safe management of animal and plant waste. Therefore, this study was carried out to chemically characterize cow manure (CM) and poultry manure (PM) after co-composting with privet and cypress residues. Results showed that heavy metals concentrations in manures varied as Fe > Zn > Mn > Cu > Ni > Pb > Cd. Addition of privet and cypress residues to both manures altered the extractability of heavy metals after composting. Higher concentrations of heavy metals were observed in manures at 1:0 ratio while lowest was noted in both CM and PM composted with plant residues at 1:2 ratio. Total K, Ca, and Mg significantly increased when CM and PM were co-composted with privet and cypress residues. There was an increase in the P content in co-composted CM with privet residual application whereas a reduction in total P was noticed with the addition of cypress plant residues in both manures. Manures amended with plant waste reduced N content. Both CM and PM retained higher NO₃ content without plant residues.     

The influence of Mg fertilization on growth and mineral contents of fine roots in (Picea abies [karst] L.) stands at different stages of decline in NE-Bavaria

The effect of various Mg-fertilizers (MgSO₄; calcined dolomite) on root growth and mineral composition of 40 yr old Norway spruce at different sites and stages of decline was studied. Two years after fertilization, density of living fine roots of Mg-deficient trees had significantly increased on fertilized compared to non-fertilized plots. Only fertilization of calcined dolomite appeared to induce new root formation in the upper mineral soil. No such changes were observed for healthy looking trees at a second experimental site, where base saturation of the bulk soil was also low but trees were sufficiently supplied with Mg. At the third experimental site where foliar analyses reflected a luxurious Ca and Mg but an insufficient K nutrition at high Mg and Ca saturation of the bulk soil, calcined dolomite caused an increase of root growth due to a reinforced antagonism between Ca and Mg competing with K uptake. In general, at the experimental sites the fine root necromass decreased when base saturation of the bulk soil increased. The elemental contents of fine roots from the mineral soil of all three sites under investigation indicated that fine root growth in the mineral soil is strongly related to the root Ca and Mg contents. Root Ca contents seemed to be mainly a function of the Ca availability in the soil. Since there was no close relationship between fine root growth and the Ca/AI molar ratio in living fine roots, Al toxicity may not completely account for the differences in root growth and nutrition on the experimental sites.