Masazumi Kayama

Effects of deicing salt on the vitality and health of two spruce species, Picea abies Karst., and Picea glehnii Masters planted along roadsides in northern Japan.

In northern Japan, the growth of Picea abies Karst., and Picea glehnii Masters, which have been planted along the highways, is often suppressed due to several environmental stresses. To examine the adverse effects of deicing salt, the primary source of stress,we measured needle life span, photosynthetic capacity, and water potential and transpiration rate of the two spruce species at a site with damaged trees, near the roadside and a site with healthy trees, located far from the highway. Results from the analysis showed large amounts of sodium and chlorine in the soil and snow at the damaged site. These elements had accumulated in the needles of the spruce. Moreover, physiological traits of the spruce, at the damaged site were also affected. Therefore, we concluded that poor physiological traits might be attributed to an accumulation of deicing salt in the needles, resulting in the suppression of tree growth.

Comparison of growth characteristics and tolerance to serpentine soil of three ectomycorrhizal spruce seedlings in northern Japan

Picea glehnii is distributed widely on serpentine soils in northern Japan. Serpentine soil is characterised by the presence of heavy metals (Ni, Cr) and excessive Mg; these elements often suppress plant growth. We have examined the tolerance to serpentine soil and its effects on growth of P. glehnii, P. jezoensis (distributed in the same region) and P. abies (planted for timber production).The dry mass of each organ was not reduced in P. glehnii planted in serpentine soil contained nursery (serpentine nursery). In contrast, growth of P. jezoensis and P. abies was suppressed. Concentrations of Ni and Mg in needles and roots of P. glehnii planted in serpentine nursery were the lowest of the three species. Moreover, the photosynthetic rate of P. glehnii planted in the serpentine nursery was not reduced. P. glehnii has high capability to maintain low concentration of Ni, and ectomycorrhizal symbiosis may have a positive effect to excluding Ni. As a result, P. glehnii has a high tolerance against Ni toxicity, and its photosynthetic capacity is not suppressed by accumulation of Ni.

Growth characteristics of ectomycorrhizal seedlings of Quercus glauca, Quercus salicina, and Castanopsis cuspidata planted on acidic soil

Key messageSeedlings of three Fagaceae species planted on acidic, infertile colluvial soil showed accelerated growth when inoculated with ectomycorrhizal fungi.AbstractWe conducted a study with seedlings of Fagaceae species inoculated with ectomycorrhizal fungi to estimate their utility for growth in acidic soil conditions. We selected Quercus glauca, Quercus salicina and Castanopsis cuspidata as typical evergreen, broad-leaved, woody species of southwestern Japan. Seedlings were inoculated with Astraeus hygrometricus or Scleroderma citrinum, and planted in acidic, infertile colluvial soil collected from an abandoned site. Six months after planting, seedlings of the three species inoculated with A.hygrometricus were growing well, especially, Q. salicina. The growth of seedlings inoculated with S. citrinum was inferior to seedlings inoculated with A. hygrometricus. In contrast, seedlings without ectomycorrhizal fungi did not grow well. Differences in growth among the three types of seedlings were related to differences in the levels of nutrient acquisition. We concluded that Fagaceae seedlings inoculated with A.hygrometricus were best suited for acidic, infertile environments.

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.

Growth of regenerated tree seedlings associated with microclimatic change in a mature larch plantation after harvesting

In order to further develop methods of sustainable forest management, we evaluated the effects of logging practices during the winter on microclimatic factors and growth of four seral deciduous broad-leaved tree seedlings regenerated in a larch plantation in northern Japan. We found that winter logging practices drastically changed microclimatic factors, especially in terms of light intensity and the vertical distribution pattern of CO2 concentration. Harvesting overstory larch trees increased photosynthetic photon flux (PPF), which may enhance the photosynthesis of understory plants. We examined the undergrowth for tree seedlings of the following species: two late successional species, Prunus ssiori and Carpinus cordata; one gap phase species, Magnolia hyporeuca; and one mid-late successional species, Quercus mongolica var. crispula. All of the four studied tree species responded well to the practices of winter logging after the second year of harvesting overstoried larch trees. The current shoot diameter and current shoot length increased significantly. Therefore, we conclude that winter logging practices should improve shoot growth of deciduous broad-leaved tree seedlings regenerated in a larch plantation through the change in environmental factors that accompanies larch harvest.

Growth characteristics of Sakhalin spruce (Picea glehnii) planted on the northern Japanese hillsides exposed to strong winds

Sakhalin spruce (Picea glehnii), a native species typically found in northern Japan, has been used in reforestation on hillsides exposed to strong winds. In the reforestation areas, there are south-facing (S-slope) and northwest-facing slopes (NW-slope). Climatic conditions are contrasting between the two slopes, with shallower snow cover on the S-slopes. We compared growth responses of the spruce to micro-environment between the S- and NW-slopes through soil nutrients, needle longevity, water status, photosynthesis, and nutrients in the needles. These parameters were measured in needles exposed above the snow in winter and in lower needles protected by snow cover. High-position needles suffered from drought stress, especially in winter, and needles were shed early in the year on both slopes. Low-position needles did not suffer from drought stress, and maintained a high photosynthetic rate on both slopes. However, needle longevity was reduced on the S-slope, and concentrations of nitrogen, phosphorus, and potassium in the needles decreased with needle age. Soil nutrient concentrations were low on the S-slope, which suggests that the needles on the S-slope may remobilize nutrients from aged needles to younger needles prior to shedding. This characteristic is probably an adaptation in Sakhalin spruce to poor soil conditions.

Differences in growth characteristics and dynamics of elements in seedlings of two birch species grown in serpentine soil in northern Japan

Key messageSeedlings of two birch species were grown in serpentine soil, withBetula ermaniishowing high tolerance.AbstractBetula ermanii and Betula platyphylla var. japonica, two typical light-demanding-deciduous trees in northern Japan, usually invade disturbed areas. B. ermanii can invade serpentine soil and grow in it, whereas B. platyphylla var. japonica can hardly regenerate in it. Serpentine soil is distributed throughout Japan and is characterized by excessive Mg and heavy metals (Ni, Cr, and Co) which can lead to suppressed plant growth. We examined the tolerance of the two Betula species by planting seedlings in serpentine and non-serpentine (brown forest) soils. The dry mass of each organ was suppressed in both birches planted in serpentine soil, and the photosynthetic rate was reduced by accumulation of Ni. Also, uptakes of K and Ca were inhibited by accumulation of Mg, Ni, Cr and Co. B. ermanii planted in serpentine soil showed high value of net assimilation rate in the second year and maintained the photosynthetic rate from June to September. The effects of Mg, Ni, Cr and Co accumulation were small on the relative growth rate of B. ermanii. In contrast, B. platyphylla var. japonica planted in serpentine soil showed decreased photosynthetic rate in September and smaller net assimilation rate than B. ermanii at the same time. In addition, B. platyphylla var. japonica showed decreased relative growth rate, induced by accumulation of Mg in leaves and Co in roots. We conclude that B. ermanii has the high advantage of regenerating in serpentine soil.

Elements and ectomycorrhizal symbiosis affecting the growth of Japanese larch seedlings regenerated on slopes of an active volcano in northern Japan

Key messageThe growth of Japanese larch seedlings is regulated by the presence of nutrients as well as ectomycorrhizal symbiosis.AbstractThe mountain slope of an active volcano is a severe environment for the regeneration of larch (Larix kaempferi Sarg. hereafter larch) seedlings. To determine parameters affecting the growth of larch seedlings, we analyzed stoichiometry of elements in the soils and plant organs, ectomycorrhizal (ECM) colonization, and photosynthetic abilities. These parameters were compared with two different elevations. From nutrient analysis of plant organs from larch seedlings grown on the slope of a volcano, potassium (K) was insufficient compared with the seedlings grown in other habitats. Symbiosis with ECM fungi enabled the uptake of nutrients, especially phosphorous (P) and nitrogen (N). The main factor affecting the differences in relative height growth rate (RHGr) of larch was attributed to ECM colonization. There was a positive relationship between ECM colonization and concentrations of P or N in needles. Larch seedlings with high rates of ECM colonization showed high concentrations of P and N, and had high photosynthetic rates. At lower elevation sites, concentrations of N and K in needles were low with high density of individuals. Moreover, larch showed a high accumulation of aluminum (Al) and iron (Fe) even though the amount of these elements in the soil was small. These seedlings exhibited a suppressed photosynthetic rate and RHGr. Symbiosis with ECM fungi could suppress the excessive uptake of Al and Fe.