Growth response ofMelaleuca cajuputi to flooding in a tropical peat swamp

We investigated the growth response ofMelaleuca cajuputi Powell to flooding at 3 sites in a tropical swamp in southern Thailand. The relative growth rate (RGR) in height tended to be higher where the water level was higher. The maximumRGR in height was achieved during the flood period at the 2 sites where water levels were higher than at the other site. The height growth ofM. cajuputi was not reduced by flooding, but enhanced. No decline in growth due to post-anoxic injury was observed after flooding.Melaleuca cajuputi may have mechanisms to tolerate rhizospheric oxygen deficiency and to avoid post-anoxic injury. This study was supported by a Grant-in-Aid for Basic Research (No. 09NP0901) from the Ministry of Education, Science, Sports, and Culture of Japan.     

Effects of flooding on growth of seedlings of woody riparian species

The effects of flooding on growth of seedlings were compared over a 7-month period (April–November) among six different woody species: Aesculus turbinata, Cercidiphyllum japonicum, Fraxinus platypoda, Pterocarya rhoifolia, Pterostyrax hispida, and Quercus mongolica var. grosseserrata. Flooding reduced the shoot length of F. platypoda, P. rhoifolia, C. japonicum, P. hispida, and Q. mongolica var. grosseserrata seedlings but did not affect that of A. turbinata seedlings. Among control seedlings, shoot elongation occurred once in A. turbinata and twice in F. platypoda and Q. mongolica var. grosseserrata; the other species continued to grow from April to August. Among the flooded plants of all species, shoot elongation occurred only once at the beginning of the growing season. On August 25, flooding significantly reduced the number of developed leaves as compared with control plants except for A. turbinata. In the flooded plants except for F. platypoda, leaf fall began on June 30; in controls, by contrast, the number of developed leaves increased until August 25. Flooding reduced the total dry weight increment in all species. The survival ratio of flooded plants after the experiment differed with species. All of the F. platypoda and A. turbinata seedlings survived the flooding treatment, while only 20% of P. hispida and 30% of Q. mongolica var. grosseserrata survived. Flooding seriously affected the growth of riparian pioneer species including P. rhoifolia, C. japonicum, P. hispida, and Q. mongolica var. grosseserrata. The effects of flooding on growth of the seedlings differed with the tree species because of differences in leaf-emergence pattern and physiological flood tolerance. The responses of tree seedlings to flooding reflected species habitats and growth patterns.     

Effects of flooding depth on growth,morphology and photosynthesis in <Emphasis Type="Italic">Alnus japonica</Emphasis> species

The present study deals with effects of flooding depth on growth, morphology and photosynthesis in Alnus japonica species thorough one field study and two controlled experiments. In the field study performed in Kushiro Mire, Hokkaido Island, Japan, tree heights and stem diameters decreased with an increase in water depth accompanied with the reduction of soil redox potential. In contrast, the rate of multiple stems per individual tree increased. In the controlled experiments for seedlings flooding suppressed the shoot elongation and biomass increment in roots. However, diameter increment around water levels, epicormic shoot development and adventitious root formation were enhanced in flooded seedlings. The photosynthetic rate and stomatal conductance of flooded seedlings also were lowered with an increase in flooding depth. The recovery of the reduced photosynthetic rate and stomatal conductance occurred simultaneously with the advancement of adventitious root formation in the flooded seedlings. These results indicate the importance of a series of morphological changes occurring on stems around water levels in flood tolerance in A. japonica species.     

The effects of flooding on several hybrid poplar clones in Northern China

The ecophysiological, morphological, and growth characteristics of 14 poplar clones were studied during 37 days of flooding and a 13-day recovery period. Cuttings were subjected to three soil water regimes, viz. drained (control), shallow flooding to 10 cm above the soil, and deep flooding to a depth of 120 cm. All hybrids modified their ecophysiological and morphological patterns to decrease carbon loss and maintain water balance. In response to flooding, all 14 hybrids reduced their expansion and initiation of new leaves, reduced height and root collar growth, and reduced the number of leaves. For shallowly flooded plants, adventitious roots developed by day 14, and their number increased with flooding duration; net photosynthesis, stomatal conductance, and growth decreased significantly compared with the control; dry weights of roots, leaves, and total biomass decreased and the allocation of growth to shoots and roots changed. After flooding ended, net photosynthesis recovered, but stomatal conductance recovered before net CO₂ assimilation since photosynthesis was limited by stomatal factor at the initial stage of stress and it was limited by non-stomatal factors over relatively long periods of stress. Transpiration and the amount of water obtained from the roots both decreased. In the deeply flooded plants, similar but often more severe changes were observed. Based on our results, we classified the hybrids into three types using hierarchical cluster analysis. Clones 15-29, 196-522, 184-411, 306-45, 59-289, DN-2, DN-182, DN-17, DN-14274, NE-222, DTAC-7, and R-270 were flood-tolerant, clone NM-6 was flood-susceptible, and clone 328-162 was moderately flood-tolerant.     

Effects of nutrition spatial heterogeneity on root traits and carbon usage by roots of Cercis chinensis seedlings in split root rooms

In natural ecosystems, nutrition available for plants shows great spatial heterogeneity. Much is known about plant root responses to the spatial heterogeneity of nutrition, but little is known about carbon usage in roots in nutrition-deficient patches and its effect on root longevity. In this study, split-room boxes were used for culture of Cercis chinensis seedlings, and the small rooms were supplied with different nutrition levels. The number of the first-order roots in the rooms with nutrition supply was significantly higher than that in the rooms with deficient nutrition. Specific root length （SRL） of the first-order roots in the rooms with deficient nutrition reached its peak at day 64 after nutrition treatment. There was no significant SRL differences between the two order roots during the experiment. Biomass of the first-order roots in the rooms without nutrition supply was significantly less than that of the first-order roots in the rooms with nutrition supply from day 64 to 96. The total biomass of the lateral roots in the rooms without nutrition supply decreased from day 64 to 96. The activities of the enzymes in roots in the rooms without nutrition supply increased and the activities of alkaline invertases in roots in the two sides of split box did not change significantly. The activities of the enzymes in roots in the rooms without nutrition supply increased gradually. These results suggest that nutrition spatial heterogeneity induced the changes in root traits and plants actively controlled carbon usage in roots in nutrition-deficient patches by regulating the activities of invertases and sucrose synthases, resulting in the reduction in carbon usage in the roots in nutrition-deficient patches.     

Effect of NaCl stress on ion distribution in roots and growth of Cyclocarya paliurus seedlings

We studied ion distribution in roots and the growth of Cyclocarya paliurus seedlings of three provenances, Huangshan in Anhui, Jiujiang in Jiangxi and Kunming in Yunnan, under conditions of 0, 1, 3 and 5 g/L NaCl stress using X-ray microanalysis. Results show that under NaCl stress of 3 and 5 g/L, the relative contents of Na⁺ and Cl⁻ in root tissues increased, while the relative contents of K⁺, Ca²⁺ and Mg²⁺ decreased. With an increase in salinity, the relative content of Na⁺ in the epidermis and cortex of the root increased, while the relative content of Cl⁻ in the stele and cortex of the root increased markedly. Thus, ions in the root tissues were unbalanced and the ratios K⁺/Na⁺ and Ca²⁺/Na⁺ decreased, while Na⁺/(K⁺+ Na⁺+Ca²⁺+Mg²⁺) increased. The decrease of the K⁺/Na⁺ ratio and the substantial increase of Cl⁻ in root tissues contributed to a decline in seedlings survival and reduced the increments for seedling leaf area, height, basal diameter as well biomass. Our preliminary conclusion is that the level of salt tolerance for the tested provenance seedlings was in the order of Huangshan > Kunming > Jiujiang, and the threshold of salt tolerance for C. paliurus seedlings was about 1 g/L. __________ Translated from Scientia Silvae Sinica, 2008, 44(6): 66–72 [틫自: 쇖튵뿆톧]     

Effects of shade on the morphology and physiology of amabilis fir and western hemlock seedlings

Successful regeneration of coastal montane sites harvested using alternative silvicultural systems may depend on the degree to which tree species can acclimate morphologically and physiologically to a variety of light environments. In a study to determine shade acclimation in montane conifers, one-year-old amabilis fir (Abies amabilis (Dougl.) Forbes) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) seedlings were grown in a nursery under four shade treatments: full sunlight (0% shade), 60% and 30% shade using shade cloth, and 30% shade using lath slats. Shading influenced shoot development, foliar physiology and morphological characteristics of both amabilis fir and western hemlock but in general, the effects were small. Shade levels of 60% were required to induce significant acclimation, and western hemlock appeared to respond more positively than amabilis fir and therefore was considered more shade tolerant than amabilis fir. Light quality had little influence on growth and development, as indicated by a lack of significant differences in physiology or morphology between seedlings grown under shade cloth or lath slats. There were indications that adequate nutrition levels may mitigate the effects of shade on seedling morphology and physiology.     

Effects of elevated CO2 concentrations on photosynthesis, dark respiration and RuBPcase activity of three species seedlings in Changbai Mountain

Two-year-old seedlings ofPinus koraiensis, Pinus sylvestriformis andFraxinus mandshurica were treated in open-top chambers with elevated CO₂ concentrations (700 μL·L⁻¹, 500 μL·L⁻¹) and ambient CO₂ concentrations (350 μL·L⁻¹) in Changbai Mountain from June to Sept. in 1999 and 2001. The net photosynthetic rate, dark respiration rate, ribulose-1,5-bisphosphate carboxlase (RuBPcase) activity, and chlorophyll content were analyzed. The results indicated the RuBPcase activity of the three species seedlings increased at elevated CO₂ concentrations. The elevated CO₂ concentrations stimulated the net photosynthetic rates of three tree species exceptP. sylvestriformis grown under 500 μL·L⁻¹ CO₂ concentration. The dark respiration rates ofP. koraiensis andP. sylvestriformis increased under concentration of 700 μL·L⁻¹ CO₂, out that ofF. mandshurica decreased under both concentrations 700 μL·L⁻¹ and 500 μL·L⁻¹ CO₂. The seedlings ofF. mandshurica decreased in chlorophyll contents at elevated CO₂ concentrations. Foundation item: This paper was supported by the National Natural Science Foundation of China (No. 30070158). Knowledge Innovation Item of Chinese Academy of Sciences (KZCX2-406) and “Hundred Scientists” Project of Chinese Academy of Sciences. Biography: Zhou Yu-mei (1973-) Ph. Doctor, Assistant Research fellow Institute of Applied Ecology. Chinese Academy of Sciences. Shenyang 110016. P.R. China. Responsible editor: Song Funan     

Effects of chronic acid fog exposure with soil acidification or nitrogen loading on nutrient status in Abies firma seedlings

To clarify the nutrient status in momi fir (Abies firma Sieb. et Zucc.) seedlings under complex stress conditions of acid fog with soil acidification or nitrogen loading, we exposed seedling shoots to simulated acid fog (pH 3) and simultaneously loaded the soil with acid or excess nitrogen for 17 months. Proton and nitrogen loading reduced K concentration in soil, but these treatments had little effect on the nutrient status of fine roots in momi fir seedlings. Acid fog exposure resulted in reduced concentrations of Mg, Al, and Fe in current-year needles and Mg, Al, Cu, Fe, and Zn in 1-year-old needles. The complex effects of acid fog exposure with proton or nitrogen loading on nutrient status were relatively slight. However, elements such as Al and Cu notably reflect the effects of proton loading. These results show that the nutrient status of trace elements, rather than major elements, in needles of momi fir seedlings is sensitive to exposure to acid fog or proton loading.     

Only two weeks are required forTricholoma matsutake to differentiate ectomycorrhizal Hartig net structures in roots ofPinus densiflora seedlings cultivated on artificial substrate

There has been conflicting debate over many years regarding the trophic status ofTricholoma matsutake (Ito et Imai) Sing., and further investigations are necessary to better understandT. matsutake physiology, particularly carbon nutrition, during ectomycorrhizal symbiosis. For this purpose, we developed a technique to rapidly synthesizein vitro ectomycorrhizas betweenPinus densiflora Sieb. et Zucc. andT. matsutake on artificial substrate (vermiculite: perlite: peat: beech sawdust; 5:5:1:1.), without added sugar in the nutrient solution. Only 1 week was required before the first rudimentary Hartig net ‘palmetti’ could be observed in roots. Well-developed Hartig net structures appeared in taproots after 2 weeks and in lateral roots after 3 weeks. Such rapid root infection may be attributed to the quality of the substrate and the inoculum used. This research was supported by a grant from the Bio-oriented Technology Research Advancement Institution (BRAIN).     

Growth,morphology and photosynthetic activity in flooded <Emphasis Type="Italic">Alnus japonica</Emphasis> seedlings

This study was conducted on Alnus japonica seedlings subjected to flooding for 2, 4, and 6 weeks to examine responses in growth, morphology, and photosynthesis to different periods of flooding. Seedlings subjected to flooding for 2 and 4 weeks were drained after flooding then watered daily. Increases in biomass of leaves, roots, and whole plants were less for 6-week-flooded seedlings. Rate of photosynthesis and stomatal conductance of flooded seedlings decreased within 2 weeks. For 2-week-flooded seedlings recovery from reduced stomatal conductance and recovery of photosynthetic activity occurred after drainage. For the 6-week-flooded seedlings stomatal conductance recovered by the end of the experiment. Adventitious root formation by the 4 and 6-week-flooded seedlings was observed from the third week of flooding. These results suggest that recovery of reduced function in leaves may progress with development of adventitious roots during the period of flooding.     

Carbon unloading in roots in relation to root senescence in Cercis chinensis seedlings under drought stress

When Cercis chinensis seedlings suffered from drought treatment, net photosynthetic rates had been significantly reduced at the end of the drought treatment. Compared with the control, the activities of acid invertases in roots had increased 5 and 11 days after drought treatment. Seventeen days after drought treatment, the activities of acid invertases in roots were significantly decreased, while activities of alkaline invertases in roots had also been significantly reduced. As the moisture in culture media decreased, so the activities of sucrose synthases in leaves decreased slightly. In roots, their activities had significantly increased 5 and 11 days after drought treatment. The contents of fructose in roots reduced as the moisture in culture media decreased and 11 and 17 days after drought treatment the reduction was significant. The content of glucose in roots clearly did not change as drought stress occurred further, but was still less than that in the control seedlings. Similarly, the content of sucrose reduced as the moisture in culture media decreased. At the beginning of the drought stress, the content of sucrose was significantly higher than that in the control and afterwards there were no differences between drought-treated seedlings and the control. The gradient of the sucrose content between leaves and roots was 0.0982 mg·g–1 FW 17 days after drought treatment, while the gradient of the seedlings under normal condition was 1.3832 mg·g–1 FW. The sucrose concentration gradient reduced by 92.9%. The reduction in the sucrose content gradient under drought stress decreased the sucrose partitioning in roots. Therefore, our results support the hypothesis of ‘shared control’.     

Effects of surface and light conditions of fallen logs on the emergence and survival of coniferous seedlings and saplings

We surveyed the germination number (N _cs) of 2-year and a 1-year survival of Abies sachalinensis and Picea jezoensis seedlings and saplings on 29 fallen logs from 2004 to 2005 in a natural coniferous forest in Hokkaido, northern Japan, in relation to the surface and light conditions of fallen logs. Moss height (H _moss), log hardness (Hardness), and the area of fallen log (Area) were measured as the surface conditions by each 1-m block from bottom to top of all fallen logs. The relative photosynthetic photon flux density (rPPFD) 10 cm above the tallest seedling in each block was measured as the light condition. In addition, the height of the tallest seedling or sapling in each block (H _max), the difference between a height of each seedling and sapling and the H _max (Shading), and a height of seedlings and saplings in 2004 (H _ini) were considered. N _cs of A. sachalinensis was affected by Hardness and Area, whereas N _cs of P. jezoensis was affected by H _moss, Hardness, Area, H _max, and rPPFD. The survival of seedlings (height < 5 cm) and saplings (5 cm ≤ height < 50 cm) were affected by H _ini, rPPFD, and shading for both species. However, the survival of P. jezoensis saplings was more sensitive to decrease in rPPFD and increase of shading than that of A. sachalinensis. Therefore, seedling emergence was influenced by surface conditions, whereas survival was affected by light conditions. Furthermore, P. jezoensis emergence and survival were more sensitive to surface and light conditions than that of A. sachalinensis.     

不同月份对互叶白千层精油得油率及主要化学成分含量的影响

为探究互叶白千层(Melaleuca alternifolia)无性系植株精油的品质,选择合适的收获时间,连续15个月取2年生互叶白千层无性系植株带叶枝条,采用水蒸气蒸馏法提取精油,采用气相色谱-质谱联用技术(GC-MS)分析不同月份精油得油率及主要化学成分含量的变化。结果表明,该无性系植株为4-松油醇型优良品系,4-松油醇平均含量高达38.39%,1,8-桉叶素含量仅为1.05%。随砍伐时间间隔的延长,得油率、4-松油醇、γ-松油烯和α-松油烯含量呈上升趋势,1,8-桉叶素含量则呈下降趋势,间隔5个月后各成分指标均符合ISO 4730:2017标准,因此建议砍伐间隔至少保持5个月以上。得油率和主要化学成分含量受收获时间影响,9月至次年2月得油率较高,尤其是次年1-2月,此时4-松油醇含量高,1,8-桉叶素含量低,所得油的品质最佳。     

Dry matter production and allocation in Eucalyptus cloeziana and Eucalyptus argophloia seedlings in response to soil water deficits

Effects of soil water availability on seedling growth, dry matter production and allocation were determined for Gympie (humid coastal) and Hungry Hills (dry inland) provenances of Eucalyptus cloeziana F. Muell. and for E. argophloia Blakely (dry inland) species. Seven-month-old seedlings were subjected to well-watered (100% field capacity, FC), moderate (70% FC) and severe (50% FC) soil water regimes in a glasshouse environment for 14 wk. There were significant differences in seedling growth, biomass production and allocation patterns between species. E. argophloia produced twice as much biomass at 100% FC, and more than three times as much at 70% and 50% FC than did either E. cloeziana provenance. Although the humid provenance of E. cloeziana had a greater leaf area at 100% FC conditions than did the dry provenance, total biomass production did not differ significantly. Both E. cloeziana provenances were highly sensitive to water deficits. E. argophloia allocated 10% more biomass to roots than did E. cloeziana. Allometric analyses indicated that relative biomass allocation patterns were significantly affected by genotype but not by soil water availability. These results have implications for taxon selection for cultivation in humid and subhumid regions.     

Organic acid exudation from the roots of Cunninghamia lanceolata and Pinus massoniana seedlings under low phosphorus stress

Organic acid exudation from the roots of Chinese fir (Cunninghamia lanceolata) and Masson pine (Pinus massoniana) seedlings under low phosphorus stress was studied using the solution culture method. The results revealed that organic acid exudation from the roots of Chinese fir and Masson pine seedlings under low phosphorus stress increased. Compared with P₃ (KH₂PO₄, 0.5 mmol/L), the average organic acid exudation from the root of Masson pine seedlings under P₀ (KH₂PO₄, 0 mmol/L), P₁ (KH₂PO₄, 0.03 mmol/L) and P₂ (KH₂PO₄, 0.09 mmol/L) increased by 328.6%, 267.9% and 126.4% respectively. Masson pine from Zhejiang Province in China had the highest organic acid exudation. Under low phosphorus stress, the increase in organic acid exudation from the different provinces of Chinese fir and Masson pine varied. Masson pine from Zhejiang Province mainly increased oxalic acid, tartaric acid, citric acid and malic acid exudation, that from Guangxi Province mainly increased oxalic acid and tartaric acid exudation, and that from Guizhou Province, China mainly increased oxalic acid, tartaric acid and malic acid exudation. Chinese fir mainly increased oxalic acid and tartaric acid exudation. __________ Translated from Journal of Nanjing Forestry University, 2007, 31(2): 9–12 [译自: 南京林业大学学报]     

Effects of overstory retention and site preparation on growth of planted white spruce seedlings in deciduous and coniferous dominated boreal plains mixedwoods

Survival and growth of planted white spruce was assessed under partial harvest treatments and different site preparation techniques in mixedwood forests of two compositions prior to logging: deciduous dominated (d-dom) – primarily comprised of mature trembling aspen (Populus tremuloides Michx.) and coniferous dominated (c-dom) – primarily comprised of mature white spruce (Picea glauca (Moench) Voss). Levels of overstory retention were 0% (clearcut), 50% and 75% of original basal area, and site preparation techniques were inverted mounding, high speed mixing, scalping and control (no treatment). The survival and growth of white spruce were assessed seven years after planting. The experiment was established as a part of the Ecosystem Management Emulating Natural Disturbance (EMEND) experiment located in northern Alberta, Canada. In the c-dom, the 50% and 75% retention of overstory resulted in reduced growth and survival of white spruce seedlings compared to clearcuts. In contrast, in the d-dom, the seedlings performed best in sites that had 50% of the overstory retained. For the c-dom, the mounding and mixing treatments yielded the best growth of spruce seedlings, while scalping yielded the worst. In the d-dom, spruce growth was highest in sites with the mixing treatment. In the d-dom, growth and survival of the planted spruce was greater than in the c-dom. The natural regeneration of deciduous trees was suppressed by the retention of canopy regardless of original composition.     

黄金宝树与福州市4种常见行道树生态效益的比较

黄金宝树是我国20世纪90年代末从澳洲等地引进的优良彩叶芳香树种。为给黄金宝树的进一步推广应用提供科学依据,将黄金宝树与4种福州市常见行道树种的生态效益进行了比较研究。结果表明:各树种的降温增湿能力排序为黄金宝树白兰花香樟杧果小叶榕,树下空气负离子平均浓度排序为黄金宝树小叶榕杧果香樟白兰花,叶片滞尘能力则表现为小叶榕杧果黄金宝树香樟白兰花。在园林或城乡绿化应用中,黄金宝树能显著增加空气负离子浓度,可与小叶榕、杧果等树种搭配,进行形式多样的景观配置,实现景观效益和生态效益的双赢。     

Effects of differences in forest floor and canopy vegetation on ectomycorrhizas ofBetula platyphylla var.japonica: A test using seedlings planted into soils taken from various sites

Effects of different forest floor vegetation types in secondary forest and of conversion to plantation on the quality and quantity of ectomycorrhizas are mostly unknown.Betula platyphylla var.japonica seedlings were used for bioassays of ectomycorrhizal fungal inoculum using soils from four 50-year-oldB. platyphylla var.japonica forests that had different types of forest floor vegetation: two with shrub types, one with aSasa type, and one with a grass type. Seedlings were also grown in soil from a nearby monospecific plantation ofChamaecyparis obtusa. Ectomycorrhizas formed 13 to 26% of root length of seedlings grown in soil from the five different sites. The maximum percentage of ectomycorrhizal formation was obtained from the grass-type forest. The dominant type of ectomycorrhiza in the two shrub-type forest soils was the same as that in theSasa-type forest soil. The dominant types of ectomycorrhizas in the grass-type forest soil and in theC. obtusa plantation soil were different from that in the two shrub-type forest soils and in theSasa-type forest soil. The results of this investigation suggest that the type of forest floor vegetation, accompanied with changes in thickness of the A₀ horizon, might affect the ectomycorrhizal fungi in the soils ofB. platyphylla var.japonica forests. Establishment of artificial plantations ofC. obtusa might change the ectomycorrhizal fungi that could associate withB. platyphylla var.japonica seedlings in soil.     

Greenhouse production of Burgundy truffle mycorrhizae on oak roots

Truffles, subterranean fruit-bodies of the ectomycorrhizal genus Tuber, are currently cultivated on host trees in plantations, both to offset declining wild production and to extend their geographic distribution. We report the effects of the potting medium and potting method components of two very different seedling production systems on the colonization of Quercus bicolor × Q. robur seedlings by T. aestivum (the Burgundy truffle). Seedlings grown in book planter containers using a peat-based medium were smaller yet much better colonized by T. aestivum than seedlings produced in RPM^® (Root Production Method) containers using a ground bark-based RPM medium. In either container method, the peat-based medium supported development of more T. aestivum mycorrhizae than did the RPM medium. Seedlings grown in book planters developed significantly more root tips l^?1 of medium than did seedlings grown in RPM containers. The optimum pH for T. aestivum mycorrhiza development in the peat-based medium is between 6.7 and 7.5.