Effect of elevated CO2 concentration on growth course of tree seedlings in Changbai Mountain

One-year-old seedlings ofPinus koraiensis, Pinus sylvestriformis, Phellodendron amurense were grown in open-top chambers (OTCs) with 700 and 500 ώmol/mol CO₂ concentrations, control chamber and on open site (ambient CO₂, about 350 ώmol/mol CO₂) respectively at the Open Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences, and the growth course responses of three species to elevated CO₂ and temperature during one growing season was studied from May to Oct. 1999. The results showed that increase in CO₂ concentration enhanced the growth of seedlings and the effect of 700 (ώmol/mol CO₂ was more remarkable than 500 ώmol/mol CO₂ on seedling growth. Under the condition of doubly elevated CO₂ concentration, the biomass increased by 38% in average for coniferous seedlings and 60% for broad-leaved seedlings. With continuous treatment of high CO₂ concentration, the monthly-accumulated biomass of shade-tolerantPinus koraiensis seedlings was bigger in July than in August and September, while those ofPinus sylvestriformis andPhellodendron amurense seedlings showed an increase in July and August, or did not decrese until September. During the hot August, high CO₂ concentration enhanced the growth ofPinus koraiensis seedlings by increasing temperature, but it did not show dominance in other two species. Foundation Item: This paper was supported by Chinese Academy of Sciences and the Open Research Station of Changbai Mountain Forest Ecosystem.     

Space-time dynamics of fine root biomass of six forests in the Maoershan forest region, northeast China

The Maoershan forestry centre is situated in the Zhangguangcai Mountain of the Changbai mountain range. The main forest types in the Maoershan region are plantation (Pinus sylvestris var. mongolica, Pinus koraiensis and Larix gmelinii) and natural secondary forests (Fraxinus mandshurica, Quercus mongolica and Populus davidiana). Fine roots have enormous surface areas, growing and turning over quickly, which plays an important role in terms of substance cycling and energy flow in the forest ecosystem. This study deals with the dynamics of live, dead, and total fine roots (≤ 5 mm) biomass in the 0–30 cm soil layer using the soil core method. Differences between the six stands in the Maoershan region showed the following results: 1) the fine root biomass in the various stands showed obvious differences. The total fine root biomass of six stands from high to low were F. mandshurica (1,030.0 g/m²) > Q. mongolica (973.4 g/m²) > Pinus koraiensis (780.9 g/m²) > L. gmelinii (718.2 g/m²) > Populus davidiana (709.1 g/m²) > Pinus sylvestris var. mongolica (470.4 g/m²); 2) except for L. gmelinii, the development of live fine root biomass agreed with the trend of total fine root biomass. The maximum biomass of live fine roots in Pinus koraiensis or L. gmelinii stand appeared in May, others in June; in the F. mandshurica stand, the minimum biomass of live fine roots occurred in September, others in July or August; 3) the proportions of dead fine root biomass varied in different stands; 4) the vertical distribution of fine roots was affected by temperature, water, and nutrients; the proportion of fine root biomass was concentrated in the 0–10 cm soil layer. The fine root biomass of six stands in the 0–10 cm soil layer was over 40% of the total fine root biomass; this proportion was 60.3% in F. mandshurica. Space-time dynamics of the various stands had different characteristics. When investigating the substance cycling and energy flows of all forest ecosystems, we should consider the characteristics of different stands in order to improve the precision of our estimates. __________ Translated from Scientia Silvae Sinicae, 2006, 42(6): 13–19 [译自: 林业科学]     

Effects of elevated CO2 on net photosynthetic rate of trees in Changbai Mountain

Net photosynthetic rates (NPRs) of four species seedlings,Pinus koraiensis, Pinus sylvestriformis, Fraxinus mandshurica andPhellodendron amurense, were measured at different CO₂ concentrations and time respectively in Changbai Mountain during the growing season in 1999. The seedlings were cultivated in open-top chambers (OTCs), located outdoors and exposed to natural sunlight. The experimental objects were divided into four groups by tree species. CO₂ concentrations in chambers were kept at 500 μL·L⁻¹ and 700 μL·L⁻¹ and contrast chamber and contrast field were set. The results showed that the effects of elevated CO₂ on NPR of the trees strongly depended on tree species and time. NPRs ofPinus koreainsis andPinus sylvestriformis seedlings increased with the rising of CO₂ concentration, while that ofPhellodendron amurense andFraxinus mandshurica increased at some time and decreased at another time. This project was supported by Chinese Academy of Sciences Responsible editor: Chai Ruihai     

Relationship between effective solar radiation and sap flow process during an entire growing season in Western Mountains of Beijing

In order to explore the relationship between the time processes of solar radiation and sap flow, sap flow velocity (SFV) of Platycladus orientalis and Pinus tabulaeformis, effective solar radiation (ESR) and other environmental factors were synchronously monitored for one year in the Beijing Western Mountains by using a thermal dissipation probe (TDP) system and an automatic weather station. Results showed significant differences between changes in diurnal characteristics of ESR and sap flow in sunny days during three seasons. Starting times of sap flow occurred generally 1.5–3 hours later than those of solar radiation and there were small differences between Platycladus orientalis and Pinus tabulaeformis. But peak times and stopping times of sap flow varied con-siderably with large contrasts in ESR. The duration of sap flow showed clear differences among the seasons owing to the variable rhythms of climate factors in Beijing. Fluctuation amplitude in the duration of sap flow remained relatively stable during the autumn but changed greatly during spring and summer. Changes in diurnal sap flow velocity of both Platycladus orientalis and Pinus tabu-laeformis were about 0–3 hours later than those of ESR but with the same configuration. The start of sap flow was mainly induced by the sudden intensification of ESR (sunrise effect). Seasonal models of SFV indicated that a cubic equation had the best fit. It was more practical to simulate seasonal water consumption models of trees with ESR. In further investigations, these models should be optimized.     

Effect of water stress on N2O emission rate of 5 tree species

The N₂O emission rates, photosynthesis, respiration and stomatal conductance of the dominant tree species from broadleaf/Korean pine forest in Changbai Mountain were measured by simulated water stress with the closed bag-gas chromatography. A total of five species seedlings were involved in this study, i.e.,Pinus koraiensis Sieb. et Zucc,Fraxinus mandshurica Rupr,Juglans mandshurica Maxim,Tilia amurensis Rupr, andQuercus mongolica Fisch. ex Turcz.. The results showed that the stomatal conductance, net photosynthetic rate and N₂O emission of leaves were significantly reduced under the water stress. The stoma in the leaves of trees is the main pathway of N₂O emission. N₂O emission in the trees mainly occurred during daytime. N₂O emission rates were different in various tree specie seedlings at the same water status. In the same tree species, N₂O emission rates decreased as the reduction of soil water contents. At different soil water contents (MW, LW) the N₂O emission rates ofPinus koraiensis decreased by 34.43% and 100.6% of those in normal water condition, respectively. In broadleaf arbor decreased by 31.93% and 86.35%, respectively. Under different water stresses N₂O emission rates in five tree species such asPinus koraiensis, Fraxinus mandshurica, Juglans mandshurica, Tilia amurensis, andQuercus mongolica were 38.22, 14.44, 33.02, 16.48 and 32.33 ngN₂O·g⁻¹DW·h⁻¹, respectively. Foundation item: This project was supported by the National Natural Science Foundation of China (No. 30271068), the grant of the Knowledge Innovation Program of Chinese Academy of Sciences (KZ-CX-SW-01-01B-10), and the Special Funds for Major State Basic Research Program of China (No. G1999043407) Biography: Wang Miao (1964-), male, associate professor in Institute of Applied Ecology, Chinese Academy of Science, Shenyang 110016, P. R. China. Responsible editor: Song Funan     

Measurement of the dynamic modulus of elasticity of wood panels

This study investigated the dynamic modulus of elasticity (DMOE) of wood panels of Fraxinus mandshurica, Pinus koraiensis, and Juglans mandshurica using the natural frequency measurement system of fast Fourier transform (FFT). The results were compared with the static modulus of elasticity (E _S) tested by a mechanical test machine. The results show a significant correlation between E _S, transverse vibration DMOE (E _F), and longitudinal vibration DMOE (E _L). For all of these species, the correlation between E _S, E _F and E _L is more significant than the individual species, which indicated that the FFT method is universal. The correlations between E _S and sample’s density (ρ) are significant, but the correlation coefficient of E _S and ρ is lower than those between E _F, E _L and E _S. The E _S of wood is more accurately tested by the analysis based on FFT measurement than by the estimation based on density. __________ Translated from Scientia Silvae Sinicae, 2005, 41(6): 126–131 [译自: 林业科学, 2005, 41(6): 126–131]     

Effects of elevated CO2 on net photosynthetic rate of trees in Changbai Mountain

lntroductionAtmosphericconcentrationofCo2isrisingdra-maticaIIyandadoubIingofthepresentconcentrationwouIdoccurinmidnextcentury,duetoburnoffossilfuelanddestroyofforest(Gates1983,Tauszetal.1996).EIevatedatmosphericCO2willchangeitsgradientdistributioninforestecoboundary,andwillproduceagreateffectontreesandthewholeforestecosystem.Atpresent,studiesoneffectsofelevatedCozonplantshavebeenapopuIartopic,especiallyoncropsrice(BateretaI.199o).HaveIkaetal.(1984)hasgainedmanyachievementsonsoybean.How-e…     

基于BP神经网络的天然云冷杉针阔混交林标准树高-胸径模型

[目的]以吉林省汪清林业局金沟岭林场12块天然云冷杉针阔混交林样地为对象,基于12 953对实测树高-胸径数据,结合林分优势高分树种(组)建立基于BP神经网络的标准树高模型。[方法]在确定隐层节点数后经过反复训练得到各树种(组)的适宜模型结构,使用相同的建模数据(8块样地)求解两个传统的树高方程,再利用未参与建模的4块样地分别验证模型。[结果]表明:落叶松、云杉的适宜模型结构(输入层节点数:隐藏层节点数:输出层节点数)为2:5:1;红松、中阔(白桦、大青杨、榆树和杂木)的适宜模型结构为2:4:1;冷杉的适宜模型结构为2:8:1;慢阔(色木、水曲柳、黄檗、紫椴和枫桦)的适宜模型结构为2:7:1。[结论]与传统方法相比,BP模型不依赖现存函数,不需要筛选模型形式,而且BP模型各树种R~2高于传统模型,平均绝对误差、均方根误差均小于传统模型,其拟合精度和预测效果均优于传统方程,可以有效地预测树高。     

Fallen wood decomposition ofPinus koraiensis andTilia amurensis

Fallen wood decomposition rate ofPinus koraiensis andTilia amurensis in broadleaved Korean pine forest was studied in this paper. The result showed that decomposition rate of fallen wood was different from that of little diameter wood and coarse woody debris for the same tree species. Fallen wood decomposition was generally rotten from outside to inside. And decomposition speed of fallen woods was different according to tree species and site, and it was also related to diameter of fallen woods. Decomposition depth ofTilia amurensis fallen wood for 17 years was 14 cm, but that ofPinus koraiensis in the same condition was less than 7 cm.Tilia amurensis was decomposed faster thanPinus koraiensis. For same tree species, if the diameter was small, the decomposition speed was quick. This project was supported by Natural Science Foundation of China (No. 39670144) and funded by the Opened Research Station of Changhai Mountain Forest Ecosystem, Chinese Academy of Sciences. (Responsible editor: Zhu Hong)     

水曲柳等树种光合、耗水及萎蔫系数比较研究

对水曲柳等10个树种净光合速率、蒸腾速率的日变化和季节变化、耗水量以及萎蔫系数进行研究的结果表明,光合速率和蒸腾速率表现出明显的日变化和季节变化,具体的日变化趋势和季节变化规律存在差异,日均净光合速率旱柳银中杨紫丁香白榆白桦水曲柳暴马丁香黄菠萝紫椴胡桃楸;日均蒸腾速率旱柳白榆银中杨黄菠萝紫丁香水曲柳白桦暴马丁香紫椴胡桃楸;单株年耗水量银中杨旱柳白桦紫丁香白榆水曲柳暴马丁香紫椴胡桃楸黄菠萝。萎蔫系数胡桃楸黄菠萝旱柳白桦紫椴银中杨水曲柳暴马丁香白榆紫丁香。     

七虎林林场黄檗野生资源的调查与分析

黄檗(Phellodendron amurense)是东北红松林的重要伴生树种,也是我国名贵重要关黄柏的药源植物。通过对七虎林林场野生黄檗植物资源状况进行野外调查,初步统计在黄檗适合的生境下,其密度平均421株.hm-2,18块20m×20m的样地中,平均胸径为6.58～18.58cm,最小胸径为5.3cm,最大胸径为46.1cm,种群主要以中幼龄林为主。     

长白山自然保护区阔叶红松林林隙更新状况

该以长白山大面积分布的阔叶红松林林隙为研究对象．系统调查了林隙形成木和林隙填充的特征，并对其主要树种的更新环境进行研究。结果表明，长白山阔叶红松林林隙多数是由1．4株形成木形成的，林隙形成木主要是红松、水曲柳、蒙古栎和紫椴；林隙填充中，紫椴和色木槭的数量最多，红松所占比例较小。不同大小林隙内填充的数量也不同，近似呈一个偏左的正态分布。现有的红松幼树一般都分布在林隙内或林隙边缘，更新环境良好。     

The contribution of root respiration of<Emphasis Type="Italic">Pinus koraiensis</Emphasis> seedlings to total soil respiration under elevated CO<Subscript>2</Subscript> concentrations

The impacts of elevated atmospheric CO₂ concentrations (500 μmol·mol⁻¹ and 700 μmol·mol⁻¹) on total soil respiration and the contribution of root respiration ofPinus koraiensis seedlings were investigated from May to October in 2003 at the Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences, Jilin Province, China. After four growing seasons in top-open chambers exposed to elevated CO₂, the total soil respiration and roots respiration ofPinus koraiensis seedlings were measured by a Li-6400-09 soil CO₂ flux chamber. Three PVC cylinders in each chamber were inserted about 30 cm into the soil instantaneously to terminate the supply of current photosynthates from the tree canopy to roots for separating the root respiration from total soil respiration. Soil respirations both inside and outside of the cylinders were measured on June 16, August 20 and October 8, respectively. The results indicated that: there was a marked diurnal change in air temperature and soil temperature at depth of 5 cm on June 16, the maximum of soil temperature at depth of 5 cm lagged behind that of air temperature, no differences in temperature between treatments were found (P>0.05). The total soil respiration and soil respiration with roots severed showed strong diurnal and seasonal patterns. There was marked difference in total soil respiration and soil respiration with roots severed between treatments (P<0.01); Mean total soil respiration and contribution of root under different treatments were 3.26, 4.78 and 1.47 μmol·m⁻²·s⁻¹, 11.5%, 43.1% and 27.9% on June 16, August 20 and October 8, respectively. Foundation item: This study was supported by the Knowledge Innovation Project of the Chinese Academy of Sciences (KZCX1-SW-01) and the National Natural Science Foundation of China (30070158). Biography: LIU Ying (1976-), female, Ph. D. Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P. R. China. Responsible editor: Song Funan     

长白赤松和红松土壤微生物活性对高浓度CO2的响应

Responses of soil microbial activities to elevated CO₂ in experiment sites ofPinus sylvestriformis andPinus koraiensis seedlings were studied in summer in 2003. The results indicated the number of bacteria decreased significantly (p<0.05) under elevated CO₂ forPinus sylvestriformis andPinus koraiensis. Amylase and invertase activities in soil increased forPinus sylvestriformis and decreased forPinus koraiensis with CO₂ enrichment compared with those at ambient (350 μmol·mol⁻¹). The size of microbial biomass C also decreased significantly at 700 μmol·mol⁻¹ CO₂. Bacterial community structure had some evident changes under elevated CO₂ by DGGE (Denaturing Gradient Gel Electrophoresis) analysis of bacterial 16S rDNA gene fragments amplified by PCR from DNA extracted directly from soil. The results suggested that responses of soil microorganisms to elevated CO₂ would be related to plant species exposed to elevated CO₂. Foundation item: The study was supported by Major State Basic Research Development Program of China (2002CB412502) and the Knowledge Innovation Project from Chinese Academy of Sciences (KZCX1-SW-01-03). Biography: JIA Xia (1975), female, Ph. D. candidate of Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P. R. China. Responsible editor: Song Funan     

Evaluation of the sap flow using heat pulse method to determine transpiration of the Populus euphratica canopy

The sap flow of the sampled Populus euphratica stems at different radial depths and directions had been studied in Ejina Oasis, in the lower reaches of the Heihe River. Based on sap flow measurements, the transpiration of the entire canopy was calculated. Results showed a linear correlation between the sap flow and the sapwood area of the P. euphratica. Through the analysis of the diameter at breast height in the sample plot, it was found that the distribution of the diameters and the corresponding sapwood area was exponentially correlated, with the coefficient of correlation being 0.976,7. The calculated transpiration of the Populus euphratica canopy was 214.9 mm based on the specific conductivity method. Translated from Scientia Silvae Sinicae, 2006, 42(7): 28–32 [译自: 林业科学]     

Effects of nitrogen on the growth and competition between seedlings of two temperate forest tree species

To understand how coexisting temperate tree species react to nitrogen (N) addition, seedlings of two coexisting species, Phellodendron amurense Rupr. and Fraxinus mandshurica Rupr. were transplanted to a controlled environment. Seedlings were then planted in two competition scenarios, control and mixed, and then subjected to four N addition treatments. The seedling growth parameters and competition effect were monitored and analyzed. The height and stem-base diameter showed a positive response to the N addition in all competition scenarios except for mixed P. amurense, which responded negatively. Chlorophyll content of the seedlings showed a positive relationship to N addition while the chlorophyll a/b showed a complex trend. The addition of N showed a positive relationship to the competition effect of diameter growth in both species and height growth in P. amurense. These results indicate that F. mandshurica may be more sensitive to N addition and could benefit more from N addition than P. amurense. With an increasing N input from the atmosphere, forests may be more suitable for F. mandshurica reducing the abundance of P. amurense.     

Feasibility of implementing thinning in even-aged <Emphasis Type="Italic">Larix olgensis</Emphasis> plantations to develop uneven-aged larch–broadleaved mixed forests

Thinning experiments were conducted in larch (Larix olgensis) plantations to assess the feasibility of converting even-aged plantation stands to uneven-aged forests with more complex stand structures. Stands established in 1965 and 1960 were thinned in 2004 (Regime A, for determining the effect of recent thinning on emergence of seedlings) and 1994 (Regime B, for examining the effects of the past thinning on establishments of recruitments), respectively, at two intensities each. Natural regeneration, together with litter depth, canopy openness and vegetation cover, was surveyed in the thinned plots. Results indicated that larch seedlings started to emerge in May, reached a peak in June, decreased from June through September, and then disappeared in October. No larch seedlings exceeded 1 year old in the thinned plots because of the low levels of light and dense litter and vegetation cover. However, there were many naturally regenerated seedlings (5–50 cm in height) and saplings (50–500 cm in height) of broadleaved tree species such as Acer spp., Fraxinus spp., Cornus controversa, Quercus mongolica, and even the climax tree species, Pinus koraiensis, in the thinned plots. The mean density of regenerated seedlings reached 6.7 and 4.5 stems m⁻² in Regimes A and B, respectively, whilst the mean density of regenerated saplings reached 4,595 stems ha⁻¹ in Regime B. These results suggest that it is impractical to turn even-aged larch plantations to uneven-aged larch forests, but it may be feasible to develop uneven-aged larch-broadleaved forests from even-aged larch plantations through thinning.     

Soil properties in forest gaps and under canopy in broad-leaved Pinus koraiensis forests in Changbai Mountainous Region, China

The species composition and diversities, and soil properties under canopy gaps in broad-leaved Pinus koraiensis forests were studied in the Changbai Mountains. The results indicated that the species composition and diversities in gap were different from those under canopy. The Shannon-Wiener index, evenness index, and abundance index in gap were higher than those under canopy in the seedling layer, while the community dominance in the seedling layer increased in closed canopy. The physicochemical properties of soil changed with the change of space and resource availability in gaps. The thickness, standing crop, and water holding capacity of the litter layer under canopy were significantly (p<0.01) higher than those in gap. The content of total nitrogen and total potassium of litter in gap were 10.47% and 20.73% higher than those under canopy, however, the content of total phosphorus and organic carbon under canopy were 15.23% and 12.66% more than those under canopy. The water content of 0–10 cm and 10–20 cm of soil layer in gap were 17.65% and 16.17% more than those under canopy. The soil buck density of 0–10 cm were slightly higher under canopy than that in gaps, but there was no significant difference in the soil buck density of the 10–20 cm soil layer. The soil pH values were 5.80 and 5.85 in gap and under canopy, respectively, and were not significantly different. The content of soil organic matter, total nitrogen, and total potassium in gap were 12.85%, 7.67%, and 2.38% higher than those under canopy. The content of NH₄ ⁺-N, available phosphorus, available potassium, and total phosphorus in soil under canopy were 13.33%, 20.04%, 16.52%, and 4.30% higher than those in gap. __________ Translated from Forest Research, 2006, 19(3): 347–352 [译自: 林业科学研究]     

The relationship between sap flow rate and diurnal change of tangential strain on inner bark in Cryptomeria japonica saplings

The relationship between sap flow rates and diurnal fluctuation of stems was investigated in cloned 3-year-old saplings of Cryptomeria japonica D. Don grown in a phytotron with irrigation every 2 days. The improved stem heat balance method and a strain gauge were used to measure sap flow rate and diurnal fluctuation of the stem. The sap flow rate reacted to lighting conditions, increasing and decreasing immediately after lights-on and lights-off, respectively. The tangential strain on the surface of the inner bark exhibited a reaction that followed but opposed the reaction of the sap flow rate to lighting conditions. Based on the changes in sap flow rate, there seemed to be four phases in diurnal sap flow: phase A₁ began with lights-on, when the sap flow rate increased, and lasted about 2 hours. In the following phase, A₂, the sap flow rate remained almost constant at 1.3 g/min for about 10 h, and then declined for about 2 h as lights-off approached. In phase B, the early period of darkness, the sap flow declined quickly and then more slowly, for about 4 h, until the start of the second dark period, phase C, when the sap flow rate became almost constant at 0.05 g/min for about 6 h. The first derivative of each sap flow rate and the corresponding tangential strain were calculated, and the results indicated a negative correlation between the two variables in all periods. In particular, the relationship between the first derivative values exhibited a highly negative correlation in phases A₁ and B, expressed as a primary formula. Sap flow rate was found to continue for some time after lights-off, and this compensated for reduced evaporative effects, albeit at a slow rate, over 4 h. The total amount of sap flow in the dark was only about 9% of that in the light, disregarding transpiration in the dark for simplicity. Thus, the total amount of sap flow responsible for swelling of the stem was about 9% of that consumed in transpiration during the light period.     

Effect of slope on growth of three hard broadleaved tree species in Northeast China

ResearchSiteThestudywascarriedoutinMaoersl1anExperimentalForestFarmofNortheastForestryUniversity(45"2O'~45"25'Nandl27"3O'~I27"34'E).Tl1eaverageeleva-tionofthisareais3OOm.Annualaveragetemperatureis2.7"C.Annualaverageprecipitationis720mm.Frost-freeperi0disl2O~l4Odays.SoiltypeistypicaIdarkbrownforests0il.Tl1evegetationbeIongstoChangbaiMountainflora.Broad-IeavedKoreanpineforestasprimitiveclimaxcommunityhasbecometypi-calnaturalsec0ndaryforestduetodisturbanceanddestroyfrommankindinrecent…