Nitrogen resorption from needles of Pinus thunbergii Parl. growing along a topographic gradient of soil nutrient availability

To examine the relative importance of nutrient resorption in increasing the nutrient-use efficiency of Pinus thunbergii Parl., we investigated the nitrogen contents of green and senescent needles of P. thunbergii trees growing at five positions along a slope (LS, lower slope; TR, transitional site; MS, middle slope; US, upper slope; RG, ridge) and found that soil nitrogen availability tended to decrease upslope. Nitrogen concentration in green and senescent needles decreased upslope. Nitrogen resorption efficiencies (percentage change in nitrogen content between green and senescent needles) increased upslope from 43 to 77% with decreasing soil nitrogen availability. Nitrogen resorption efficiency was related to green needle dry mass per unit length, but there was no clear correlation between nitrogen resorption efficiency and nitrogen content in green needles. We concluded that the increase in nitrogen resorption efficiency of P. thunbergii enhanced the nitrogen-use efficiency as a response to the low nitrogen availability.     

海岸抗风植物黑松对净风和风沙流的生理响应

利用野外便携式风洞仪对盆栽黑松（Pinus thunbergii Parl）幼株在不同风速（6、9、12、15、18 m/s）、不同风沙流强度（0、1.00、28.30、63.28、111.82、172.93 g cm^-1 min^-1）、不同时间（10、20、30、40、50 min）进行了净风和风沙流吹袭,通过测定其叶片相对含水量（Relative water content,RWC）、丙二醛（Malondialdehyde,MDA）、可溶性糖、脯氨酸含量,及超氧化物歧化酶（superoxide dismutase,SOD）、过氧化氢酶（Catalase,CAT）、过氧化物酶（Peroxidase,POD）活力等变化规律以揭示黑松抗风沙流生长的生理适应机制。结果表明,在净风吹袭下,随着风速提高至15 m/s,黑松叶片RWC相对稳定,MDA含量和细胞膜透性小幅增加且较低,而脯氨酸含量下降17.5%。同时叶片SOD、CAT、POD活力也小幅增加。在风沙流吹袭下,随着风沙流风速提高至15 m/s,黑松在短时低风速吹袭时叶片RWC就开始下降（4.4%）,叶片平均MDA含量、细胞膜透性分别较对照增加61.3%、25.6%,脯氨酸含量增加8.9%,叶片SOD、CAT、POD活力分别较对照增加21.5%、30.4%、13.9%。同风速吹袭下,风沙流处理组叶片抗逆生理指标均高于净风处理。如15 m/s风速下,风沙流处理组叶片平均MDA、脯氨酸、可溶性糖含量分别较净风处理组高4.7%、36.6%、22.1%,SOD和CAT活力较净风处理组高21.5%、36.5%。在高风速（18 m/s）净风和风沙流吹袭中,随着风吹时间延长（50 min）,叶片MDA、脯氨酸、可溶性糖含量和SOD、CAT、POD活力均下降。研究表明,风吹袭中黑松叶片较高抗脱水力与其抗风性相关。风沙流引发的叶片失水可能是黑松抗逆生理变化的诱因。风吹袭下叶片失水能快速促使脯氨酸的积累和维持可溶性糖含量,以维护细胞中水分平衡。同时,叶片失水又快速激活抗氧化保护酶系统来防御和清除氧自由基、抑制膜脂过氧化维护细胞膜的完整性使黑松在风沙流吹袭中生存。黑松较强的渗透调节能力和抗氧化防御系统在其适应风沙流吹袭中起重要的生理调控作用。     

Topographic variations of soil properties and stand structure in aPinus thunbergii plantation

Soil properties and above-and belowground forest structure were studied across various topographies in a 20-year-oldPinus thunbergii Parl. plantation on Mt Tanakami, Japan. The soil properties and stand structure varied greatly with slope position fromridge top to valley floor. Soil thickness, fine soil content and soil moisture content were greater in lower slope positions. The amount of organic carbon in the forest floor was greater in upper slope positions. The organic carbon content in the mineral soil was slightly greater in lower slope positions. These changes in soil properties suggested an upslope decrease in decomposition rate and water and/or nutrient availability. The aboveground structure ofP. thunbergii was more developed at lower slope positions. The mean stem diameter, height and volume ofP. thunbergii increased downslope with decreasing tree density. However, fine root biomass increased greatly upslope. This inverse relationship between tree height and fine root biomass indicated morphological plasticity ofP. thunbergii in exploiting environmental heterogeneity. Variations in soil-plant interactions in the stand along various topographies caused spatial heterogeneity in the accumulation pattern of organic matter in plants and the soil.     

Tolerance ofPinus densiflora,Pinus thunbergii,andLarix leptolepis seedlings to SO2

Summary Effects of exposure to SO₂ at 0.5, 1.0, and 1.5 ppm for 48 hours on sulfur uptake, needle injury, height growth, diameter growth, dry weight increment, and relative growth rate of seedlings of three species of gymnosperms were investigated in a controlled environment. On the basis of such responses as needle injury, dry weight increment, relative growth rate, and diameter growth, tolerance to SO₂ 60 days after treatment varied in the following order:Pinus thunbergii (most tolerant),Pinus densiflora, Larix leptolepis (least tolerant). On the basis of height growth response the order of SO₂ tolerance was:Pinus densiflora>Pinus thunbergii>Larix leptolepis. The range of response to SO₂ of the three species varied with the specific response measured. The usefulness of relative growth rate as a pollution response is emphasized because of differences among species in initial size and growth rate. Limitations of using height growth responses to determine pollution tolerance are discussed. Caution is advised in constructing tables of pollution tolerance of plants by using data of investigators who apply different criteria for assessing plant responses to air pollution.Research supported by the College of Agricultural and Life Sciences, University of Wisonsin, Madison, Wisconsin, USA and by Yamagata University, Tsuruoka, Japan. McIntyre-Stennis, Project 2599.     

Effects of N-immissions on nutrient status and vitality ofPinus sylvestris near a hen-house

Near a hen house (50–600 m), vitality ofPinus sylvestris, N-, P-, K-, Ca-, Mg-contents of the needles, N-, Mg-, K-, Ca- and Al-contents in soil extracts and NH₃/NH ₄ ⁺ -contents of the air were determined. Damage symptoms occurred when N-immissions hit the canopy directly. In contrast no visible decline of the above ground plant could be observed if N was mainly deposited on the soil.     

Influence of Norway spruce seedlings on the nutrient availability in mineral soil and forest floor material

A greenhouse experiment was performed to evaluate the effect of Norway spruce (Picea abies (L.) Karst.) seedlings on net nutrient availability in five different growing media containing F- or H-layer and mineral soil originating from a haplic podzol in northern Sweden. The initial total amounts of eight nutrient elements (N, K, P, Ca, Mg, Mn, Fe, Zn) and exchangeable amounts of the same elements were analyzed in pots with or without spruce seedlings. In the planted pots seedling nutrient uptake was also estimated. After 26 weeks, higher net nutrient availability with seedlings was found in 25 out of the 40 (62%) growing media and nutrient element combinations. A positive seedling effect on net nutrient availability might be explained by rhizodeposition stimulating the soil microorganism activity and accelerating the weathering of minerals or by seedling roots promoting the nutrient providing processes through changes in soil chemical and physical properties. Nitrogen availability was primarily affected by what part of the forest floor the growing medium contained although the positive response to seedling presence was apparent. The positive net availability response of P, Ca, Mg, Mn, Fe and Zn to seedling presence was on the other hand relatively strong. In the case of P, K, and Zn the growing medium composition (if the F- and H-layer was pure or mixed with mineral soil) was also an important factor for the estimated net availability. Pure F-and H-layer provided greater P- and K-availability while the availability of Zn increased when mineral soil was added. The influence of growing plants ought to be considered when soil samples are used for assessing the nutrient availability.     

亚热带红壤侵蚀区马尾松针叶养分含量及再吸收特征

叶片衰老过程中的养分再吸收是植物适应养分贫瘠生境的一种重要策略,一直是生态学领域的研究热点。以亚热带红壤侵蚀区生态恢复先锋树种马尾松为研究对象,分析4种不同恢复水平下马尾松叶片养分含量随叶龄的变化情况及养分再吸收特征。结果表明:(1)叶片中N、P、K含量变化范围分别在(6.10±0.52)—(12.02±0.85)mg/g、(0.17±0.03)—(1.02±0.01)mg/g、(1.58±0.49)—(9.46±0.90)mg/g,随叶龄增长整体呈先增加后降低的趋势,具有一个快速积累期和一个相对漫长衰减期的动态特征,这表明叶龄也是影响叶片养分含量的重要因素;(2)叶片N、P、K含量随生境恢复水平的提高而增加,且N、P含量在除凋落叶外的叶龄阶段均表现出显著正相关,表明叶片中这两种营养元素在动态变化上存在协同性;(3)在叶片N、P、K再吸收效率中,P、K再吸收效率较高,而N相对较低。养分再吸收受生境中营养元素的含量水平、循环方式等因素的综合影响表现出一定选择性,对生境中较为贫瘠或使其生长受到限制的元素具有较高的再吸收效率。这不仅可以减小植物对外源养分的依赖性,同时也维持了体内重要营养元素的平衡。随叶龄增长叶片中N/P逐渐增大,反映出在叶片衰老过程中对限制元素P具有较强的再吸收能力,这种反馈调节提高了马尾松对养分贫瘠环境的适应性。本文的研究结果可为亚热带红壤侵蚀退化区先锋物种在贫瘠生境条件下的养分利用机制与适应对策方面的研究提供理论依据。     

Effect of nutrient availability on hyphal maturation and topographical sensing in Aspergillus niger

Topographical sensing (thigmotropism) is an essential component of efficient fungal growth. It is an important element in the complex pathway of sensory and mechanical elements that drive and control the growing hyphal tip, a fuller understanding of which will bring the mycological community a step closer to complete comprehension of the hyphal growth mode. Previous work has led us to hypothesize that the stress induced by nutrient deficiency causes structural changes in the hyphal tip that induces a thigmotropic response in Aspergillus niger, a soil fungus that does not display thigmotropism under normal conditions. In this study, we have sought to identify some of the factors that influence this induction of thigmotropism using a novel combination of microengineered substrates and imaging and analysis techniques to quantify thigmotropic behavior in complex hyphal systems. We have shown that the sensitivity of fungal contour sensing appears to be directly linked to nutrient availability and hypothesize that this may be caused by a stress-induced flattening of the tip and increased immaturity of the hyphal apex. Parts of this paper were presented at the Mycological Society of Japan (MSJ)/British Mycological Society (BMS) Joint Symposium, “The new generation of mycologists in Japan and the UK” held in Chiba, Japan, on June 3, 2006.     

不同林龄刺槐叶片养分重吸收特征及其对土壤养分有效性的响应

为揭示丘陵沟壑区刺槐的养分重吸收特征及其驱动因素,研究该区不同林龄刺槐叶片全氮和全磷的浓度,以及土壤有机碳、全氮、全磷、铵态氮、硝态氮和速效磷浓度及其化学计量,分析了叶片氮磷重吸收效率与土壤养分特性之间的关系。结果表明: 植物和土壤的养分随林龄增长发生显著变化,而土壤总磷和速效磷浓度较低。氮重吸收效率随林分生长先增加后降低,范围为48.2%～54.0%,平均为48.5%;磷重吸收效率则显著增加,范围为45.2%～49.4%,平均为46.9%。氮重吸收效率与土壤氮素和氮磷比呈负向响应,而磷重吸收效率与氮磷比呈显著正相关,与土壤速效磷呈负相关。表明土壤养分有效性的变化负向驱动养分重吸收效率。由于该生境中刺槐林的固氮效应及磷限制,叶片养分重吸收策略对土壤氮磷比响应强烈。     

Competition and coexistence of rhizomatous perennial plants along a nutrient gradient

I studied competition and coexistence of three tall clonal perennial plant species, Calamagrostis epigejos (L.) Roth, Solidago canadensis L., and Tanacetum vulgare L. along a gradient of soil productivity over five years. A replacement series field experiment was conducted with high, moderate and low fertility levels in 1m×1m plots. There were significant effects of soil type on ramet density (P<0.001), mean height (P<0.01), and total biomass (P<0.01). Ramet density, mean height, and total biomass increased with increasing soil fertility. There were also significant effects of mixture on ramet density (P<0.01), but not on mean height and total biomass for all species. Significant neighbor effects on ramet density and total biomass (P<0.01) were found for Solidago, showing that it is important whether Tanacetum or Calamagrostis is its neighbor within mixtures. During the five years there was only one case of competitive exclusion: Calamagrostis excluded Solidago on the most fertile substrate in the fifth growing season. In most cases species coexisted over the five years. Each of the three species was able to dominate in at least one combination of substrate type and mixture. The experiment showed that asymmetric competition for light on substrates of high fertility, symmetric competition for nutrients on nutrient-poor soil and positive interactions especially on substrates of intermediate fertility played a role. A founder effect was evident in aggregated mixtures of Calamagrostis and Solidago on the nutrient-rich substrate. A conceptual model of the relative importance of root competition for soil nutrients, shoot competition for light, and positive interactions along the fertility gradient is presented. The model emphasizes that positive interactions play an important role over a broad range of the productivity scale with a peak at intermediate levels of fertility. On the substrate of high productivity shoot competition for light is more important than positive interactions and root competition for soil nutrients as well. The competitive superiority of Calamagrostis on the most productive substrate was evident only in the long run. Rare events like extreme summer drought or selective herbivore pressure caused a switch in dominance in mixtures with Solidago, respectively Tanacetum. The guerrilla growth strategy of Calamagrostis and interference competition through a dense cover of aboveground biomass and litter could further cause competitive exclusion.     

Change in Water Status of Pinus thunbergii Parl. Inoculated with Species of Bursaphelenchus

Maximum and minimum xylem pressure potentials of needles were measured to evaluate water status of Pinus thunbergii Parl. after inoculation with the virulent or avirulent populations of Bursaphelenchus xylophilus or B. mucronatus. In virulent B. xylophilus-inoculated pines, the water status changed abruptly and needle chlorosis occurred by day 29 after inoculation. Similar changes were not seen in B. mucronatus-inoculated and uninoculated control pines. Oleoresin flow ceased in virulent B. xylophilus-inoculated pines. Avirulent B. xylophilus-inoculated pines responded very little to nematode invasion by a slight decrease in oleoresin flow. Oleoresin flow did not vary in B. mucronatus-inoculated and uninoculated control pines. A decrease in soil water potential below field capacity seemed to accelerate the development of pine wilt disease.     

Initial nitrogen content and topographic moisture effects on the decomposition of pine needles

The effects of litter quality and site characteristics on the decomposition process were investigated using a litterbag method. Pine needle litters with differing nitrogen concentrations (0.8, 0.6 and 0.4%) were placed on the upper and lower slopes of a Pinus thunbergii Parl. plantation. After both 3 and 6 months, the mass of decomposing litter with the lower nitrogen concentration was larger than the litter with higher nitrogen concentrations. After 9 months, there were no significant differences in the litter mass remaining, regardless of the initial nitrogen concentration. Moisture content in the litter was always higher on the lower slope, although the mass of litter was smaller. Nitrogen concentration of the decomposing litter increased linearly with accumulated mass loss. The increase in nitrogen concentration of decomposing litter was greater on the lower slope, but this increase did not differ between initial nitrogen concentrations. The nitrogen release from the decomposing litter with higher initial nitrogen concentration was larger than the release from litter bags with lower nitrogen concentrations. This result suggests that there may be positive feedback between soil nutrient availability, litter quality and nutrient release from decomposing litter at the intraspecific level.     

Temporal and spatial variability in soil nutrient status of a former beach plain

As part of a research project on the variation in life-history characteristics within a population of Plantago major L. ssp. pleiosperma, seasonal and spatial variability in the availability of macronutrients (N, P, and K) were examined on a small scale in the 0–25 cm soil depth at a primary beach plain site, embanked since 1966. On the basis of distinct differences, among other things, in plant biomass, an a priori division into three different types of microhabitat occurring in a mosaic distribution pattern was made: an overall low-lying area (subsite 1) with slightly elevated patches of 0.5 to 1.5 m in diameter (subsite 2) and rather large patches, 20 to 40 m in diameter, of sea buckthorn shrubs, with small and relatively open spots (subsite 3) in the transitional zone from lower area into scrub. All three subsite types were studied within a total area of approximately 2000 m². Three methods of analysis were applied: an inventory survey (sampling once at the start of the growing season), an analysis of the seasonal variation (sampling at approximately monthly intervals during the period April-November), and an assessment of nitrogen mineralization potentials in the laboratory (sampling once at the beginning of the growing season). All three procedures clearly demonstrated the occurrence of differences in the availability of nutrients over very short distances, i.e. a pronounced spatial variability among subsites. Particularly the availability of N and P appeared to have increased at the subsites 2 and 3, when compared to subsite 1. This small-scale differentiation in soil properties has occurred in an essentially homogeneous parent material (e.g. in texture and carbonate content) over a period of about 20 years. Besides a spatial variability, statistically significant temporal fluctuations were observed in the availability of N, P, and K. Relative fluctuations of mineral N (as indicated by the range/mean ratio) were especially large at the subsites 2 and 3.     

A soil nutrient gradient in Magellanic Empetrum heathlands

The relationship of environmental and soil-nutrient variables with the floristic composition of Empetrum rubrum heathlands and related communities from northern Tierra del Fuego were studied by means of ordination techniques. A floristic gradient was found which had its axis of major variation closely related to a gradient in soil trophic status. Increases in the densities of Empetrum and other cushion plants (Bolax gummifera, Azorella lycopodioides, Pernettya pumila) along the floristic gradient were: (a) associated with a lower number of species and total cover, and greater soil erosion; (b) positively correlated with the C/N ratio and aluminium content in the soil; and (c) negatively correlated with pH, calcium content and base saturation.Climate, lithology, habitat exposure, and the history of human activity would be key factors in developing the oligotrophic conditions that favoured the establishment of different Empetrum heathlands.     

Lecanosticta acicola, causal fungus of brown spot needle blight inPinus thunbergii, new to Japan

A needle blight disease with brown spots was found on ornamental trees ofPinus thunbergii in Shimane Prefecture, Japan. The causal fungus was identified asLecanosticta acicola, known as causal fungus of brown spot needle blight of pines recorded in the Americas, Europe, and China.Pinus thunbergii was heavily infected following inoculation with the fungus in June, but only slightly infected following inoculation in September. The mycelia of the fungus were raised and produced conidial masses on potato-dextrose and Waksman agars. They grew well at 20–25°C within the range of 5 to 35°C.     

Plant nutrient efficiency: A comparison of definitions and suggested improvement

Selection of plant cultivars tolerant of low nutrient supply may increase productivity on low fertility soils and reduce fertilizer requirements. Considerable effort has been directed towards identifying nutrient efficient species and germplasms, but the many different definitions for efficiency make the use of the term ambiguous. The concept of nutrient efficiency was evaluated using data from a study of differences in germplasm response to phosphorus (P) availability in white clover (Trifolium repens L.) and alfalfa (Medicago sativa L.) grown in a sand-alumina culture. Application of various criteria identified in the literature as measures of nutrient efficiency did not clarify differences between purportedly P efficient and inefficient germplasms. Germplasms differed in maximum shoot and total dry mass and in solution P concentration required to achieve 80% maximum yield, but not in tissue P concentration, internal P utilization, or P uptake per unit of fine root dry mass. Differences may have resulted from factors other than efficient use of available P. To reduce the confounding effects that other factors have on nutrient efficiency, we propose that equivalent yields of germplasms be demonstrated where nutrients are not limiting. Mechanisms that enable enhanced nutrient efficiency can be identified less ambiguously using this improved approach.Joint contribution of the Minnesota Agricultural Experimental Station, USDA-ARS and US Dairy Forage Research Center (Minnesota cluster). Paper No. 20,432 of the Minnesota Science Journal Series.Joint contribution of the Minnesota Agricultural Experimental Station, USDA-ARS and US Dairy Forage Research Center (Minnesota cluster). Paper No. 20,432 of the Minnesota Science Journal Series.     

Growth of the tropical Pinus kesiya as influenced by climate and nutrient availability along an elevational gradient

与温带地区相比,人们对在热带山脉中,尤其是热带针叶林中,沿海拔梯度的个体树种生长减少的原因知之甚少。我们的研究目的是检验气候或土壤条件是否会导致在高海拔分布的卡西亚松(Pinus kesiya,一种在南亚和东南亚广泛分布的松树)的生长减少。我们对越南中南部山脉中沿海拔梯度约在900~2000米之间的卡西亚松的树干直径增量和其年轮中13C(△13C)的同位素判别进行分析。同时确定其生长与△13C、气候和土壤变量的关系。研究发现,树木的断面积生长量(BAI)与温度或降水之间没有一致的相关关系。相反,沿海拔梯度,我们发现BAI与△13C以及与上层矿质土壤的C/N比和δ15N特征呈显著负相关。BAI与土壤中有效磷(Pa)和“碱性”阳离子(钙、镁、钾)的浓度呈正相关。我们的结论是,较高海拔下的较低温度会对树木生长产生间接影响,主要通过产生较高的C/N比并降低氮(N)和P矿化率而产生作用,而这些影响因其他负面反馈而进一步受到阻碍。主要包括：降水增加的淋溶作用而导致较低浓度的“碱性”阳离子以及较高海拔土壤矿化的N和P的有效性降低。本研究结果可以进一步解释卡西亚松的最高生长极限以及该物种在其他山区出现的情况     

Nutrient accumulation and distribution of wheat genotypes in response to waterlogging and nutrient supply

The effect of soil waterlogging and nutrient supply on plant nutrient accumulation and distribution was investigated for two genotypes of winter wheat (Triticum aestivum L.) differing in waterlogging resistance, Bayles and Savannah. Plants were grown in waterlogged or drained sand and fertilized with half-strength or full-strength Hoagland's solution.Waterlogging reduced the concentrations of N, P, K, Mg, and Zn in leaves and stems and increased the concentrations of those elements in the root system. The effects were greater for waterlogging-sensitive Bayles than for waterlogging-resistant Savannah. Higher concentrations of Fe and Mn were found in waterlogged plants compared to the control plants for sensitive Bayles. Waterlogging increased the proportion of N and Zn in the root system and decreased that of K in stems for Bayles. The proportion of Fe increased in leaves and stems for Bayles and Savannah under waterlogged conditions, but to a greater extent for Bayles. Doubling the concentrations of all major and minor nutrient elements supplied to the waterlogged rooting medium improved plant nutrient status and enhanced plant dry matter production.     

Effects of nitrogen fertilization of grapefruit trees on soil acidification and nutrient availability in a Riviera fine sand

Nitrogen (N) fertilizer applied in the NH4+ form results in some degree of soil acidification, which could influence nutrient availability to plants and nutrient losses through leaching. Effects of various N rates (0 – 168 kg N ha-1 yr-1) on soil acidification and nutrient availability were investigated in a Riviera fine sand with 26-year-old white Marsh grapefruit (Citrus paradisi MacFadyen) trees. Soil pH significantly decreased with increasing NH4–N rates. Application of 112 kg N ha-1 yr-1 for four years decreased the pH by 0.7 to 1.7 unit. Soil acidification was greater when the NH4+ form of N fertilizer was applied as dry soluble granular material compared to fertigation or controlled release forms. The marked effect of NH4–N fertilization on the pH of the Riviera fine sand was due to its low buffering capacity. Soil acidification increased the concentration of extractable Fe and P but decreased that of K, Zn and Mn. Soil pH was positively correlated with concentration of Ca, but negatively with concentrations of Fe, Mn and Zn in six-month-old spring flush leaves of the grapefruit trees. Leaf P concentrations, however, were poorly correlated with soil pH. This study also demonstrated an increase in leaching of P and K below the grapefruit trees rootzone with a decrease in soil pH.     

Carbon assimilation, nitrogen, and photochemical efficiency of different Himalayan tree species along an altitudinal gradient

In the area of Jumla region in Western Nepal, measurements of saturated leaf net photosynthetic rate (P_sat), nitrogen content, leaf fluorescence, carbon isotopic composition, and water status were performed on woody coniferous (Pinus wallichiana, Picea smithiana, Abies spectabilis, Juniperus wallichiana, Taxus baccata), evergreen (Quercus semecarpifolia, Rhododendron campanulatum), and deciduous broadleaved species (Betula utilis, Populus ciliata, Sorbus cuspidata) spreading from 2 400 m up to the treeline at 4 200 m a.s.l. With the exception of J. wallichiana, P_sat values were lower in coniferous than broadleaved species. Q. semecarpifolia, that in this area grows above the coniferous belt between 3 000 and 4 000 m, showed the highest P_sat at saturating irradiance and the highest leaf N content. This N content was higher and P_sat lower than those of evergreen oak species of tempe forests at middle and low altitudes. For all species, P_sat and N content were linearly correlated, but instantaneous nitrogen use efficiency was lower than values measured in lowland and temperate plant communities. The values of carbon isotopic composition, estimated by ₁₃C, showed the same range reported for temperate tree species. The ranking of ₁₃C values for the different tree types was conifers < evergreen broadleaved13C were found along the altitudinal gradient. Quantum yield of photochemistry at saturating irradiance, measured by leaf fluorescence (F/F_m), was highest in J. wallichiana and lowest in T. baccata. Overall, photochemical efficiency was more strongly related to species than to altitude. Interestingly, changes of .F/F_m along the altitudinal gradient correlated well with the reported altitudinal distribution of the species.This revised version was published online in March 2005 with corrections to the page numbers.