Effect of elevated CO2 concentration on growth course of tree seed-lings in Changbai Mountain

One-year-old seedlings of Pinus koraiensis, Pinus sylvestriformis, Phellodendron amurense were grown in open-top chambers (OTCs) with 700 and 500 mmol/mol CO2 concentrations, control chamber and on open site (ambient CO2, about 350 mmol/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 mmol/mol CO2 was more remarkable than 500 mmol/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-tolerant Pinus koraiensis seedlings was bigger in July than in August and September, while those of Pinus sylvestriformis and Phellodendron 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 of Pinus koraiensis seedlings by increasing temperature, but it did not show dominance in other two species.     

Response of seedlings of different tree species to elevated C02 in Changbai Mountain

Eco-physiological responses of seedlings of eight species,Pinus koraiensis, Picea koraiensis, Larix olgensis, Populus ussuriensis, Betula platyphylla, Tilia amurensis, Traxinus mandshurica andAcer mono from broadleaved/Korean pine forest, to elevated CO₂ were studied by using open-top chambers under natural sunlight in Changbai Mountain, China in two growing seasons (1998–1999). Two concentrations of CO₂ were designed: elevated CO₂ (700 μmol·mol⁻¹) and ambient CO₂ (400 μmol·mol⁻¹). The study results showed that the height growth of the tree seedlings grown at elevated CO₂ increased by about 10%–40% compared to those grown at ambient CO₂. And the water using efficiency of seedlings also followed the same tendency. However, the responses of seedlings in transpiration and chlorophyll content to elevated CO₂ varied with tree species. The broad-leaf tree species were more sensitive to the elevated CO₂ than conifer tree species. All seedlings showed a photosynthetic acclimation to long-term elevated CO₂. Foundation item: The project was supported by National Key Basic Development of China (G1999043400) and the grant KZCX 406-4, KZCX1 SW-01 of the Chinese Academy of Sciences Biography: WANG Miao (1964-), maie, associate professor in Institute of applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P. R. China. Responsible editor: Song Funan     

Response of seedlings growth ofPinus sylvestriformis to atmospheric CO2 enrichment in Changbai Mountain

The biomass and ratio of root-shoot ofPinus sylvestriformis seedlings at CO₂ concentration of 700 μL·L⁻¹ and 500 μL·L⁻¹ were measured using open-top chambers (OTCs) in Changbai Mountain during Jun. to Oct. in 1999. The results showed that doubling CO₂ concentration was benefit to seedling growth of the species (500 μL·L⁻¹ was better than 700 μL·L⁻¹) and the biomass production was increased in both above-ground and underground parts of seedlings. Carbon transformation to roots was evident as rising of CO₂ concentration. This project is supported by Chinese Academy of Sciences Responsible editor: Chai Ruihai     

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     

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     

大气CO2倍增对长白山不同树种的苗木的影响

组成长白山阔叶红松林的主要树种红松、云杉、落叶松、大青杨、白桦、椴树、水曲柳和色木的幼树,盆栽于模拟自然光照和人工调节CO2浓度为700祄olmol-1、400祄olmol-1的气室内两个生长季(1998-1999),以生长在400祄olmol-1下的幼树为对照组。研究结果表明:高CO2浓度下生长的红松、云杉、落叶松、大青杨、白桦、椴树、水曲柳和色木的高生长比对照组的幼树提高10%~40%。水分利用效率均有不同程度的提高,但不同树种叶绿素含量和蒸腾速率对高CO2浓度反应不一。长期高CO2浓度环境下生长的阔叶树对大气CO2浓度升高反应较针叶树敏感,供试8个树种对CO2浓度的升高均发生光合驯化现象。图2表2参24。     

Effect of elevated ambient CO2 concentration on water use efficiency ofPinus sylvestriformis

Pinus sylvestriformis is an important species as an indicator of global climate changes in Changbai Mountain, China. The water use efficiency (WUE) of this species (11-year old) was studied on response to elevated CO₂ concentration at 500±100 μL·L⁻¹ by directly injecting CO₂ into the canopy under natural condition in 1998–1999. The results showed that the elevated CO₂ concentration reduced averagely stomatal opening, stomatal conductance and stomatal density to 78%, 80% and 87% respectively, as compared to normal ambient. The elevated CO₂ reduced the transpiration and enhances the water use efficiency (WUE) of plant. The project was supported by Chinese Academy of Sciences Responsible editor: Chai Ruihai     

Soil CO2 evolution from Korean pine virgin forest at Changbai Mountain

The soil CO₂ evolution rate was measured in a virgin Korean pine forest. The results in June showed that the lowest value of evolution rate was 220 mg/(m²·h) and appeared at 6:00 a.m. The highest value was 460 mg/(m²·h) at 18:00. The rates of CO₂ evolution were related with soil temperature. On the basis of the constructed regression equation and the monthly average values of temperature, the magnitude of CO₂ evolution from Korean pine forest soil was 10.4 t/hm² during a growing season. This project was funded by the Opened Research Station of Changbai Mountain Forest Ecosystem, Chinese Academy of Sciences. Responsible editor: Zhu Hong     

Effects of elevated CO2 concentrations on soil microbial respiration and root/rhizosphere respiration in forest soils

The two main components of soil respiration, i.e., root/rhizosphere and microbial respiration, respond differently to elevated atmospheric CO₂ concentrations both in mechanism and sensitivity because they have different substrates derived from plant and soil organic matter, respectively. To model the carbon cycle and predict the carbon source/sink of forest ecosystems, we must first understand the relative contributions of root/rhizosphere and microbial respiration to total soil respiration under elevated CO₂ concentrations. Root/rhizosphere and soil microbial respiration have been shown to increase, decrease and remain unchanged under elevated CO₂ concentrations. A significantly positive relationship between root biomass and root/rhizosphere respiration has been found. Fine roots respond more strongly to elevated CO₂ concentrations than coarse roots. Evidence suggests that soil microbial respiration is highly variable and uncertain under elevated CO₂ concentrations. Microbial biomass and activity are related or unrelated to rates of microbial respiration. Because substrate availability drives microbial metabolism in soils, it is likely that much of the variability in microbial respiration results from differences in the response of root growth to elevated CO₂ concentrations and subsequent changes in substrate production. Biotic and abiotic factors affecting soil respiration were found to affect both root/rhizosphere and microbial respiration. __________ Translated from Journal of Plant Ecology, 2007, 31(3): 386–393 [译自: 植物生态学报]     

Effects of elevated CO2 concentration on the respiratory behavior of the branches of field-grown hinoki cypress (Chamaecyparis obtusa)

The effects of elevated atmospheric CO₂ concentrations on the nighttime respiration were examined for two sample branches of a hinoki cypress tree (Chamaecyparis obtusa) growing in the field with an open gas exchange system for a one-year period from July 1994 to June 1995. The branches were of a similar size and located at a similar position within the crown. One branch was subjected to an elevated CO₂ concentration of 800 μmol mol⁻¹ and the other was subjected to ambient air which had a CO₂ concentration of about 370 μmol mol⁻¹. Nighttime respiration rate was higher in elevated CO₂ level than in ambient CO₂ level. The relationship between nighttime respiration and the corresponding nighttime air temperature was fitted by the exponential function in every month of the year. The segregation of regression lines between the two CO₂ treatments increased gradually as the seasons progressed during the treatment period. TheQ ₁₀ values for nighttime respiration were lower in elevated CO₂ (1.9 ≤Q ₁₀ ≤ 3.7) than in ambient CO₂ (2.4 ≤Q ₁₀ ≤ 4.5) in every month of the year. TheQ ₁₀ was inversely related to the monthly mean nighttime air temperature in both elevated and ambient CO₂. The estimated daily nighttime respiration rate under both CO₂ treatments had a similar seasonal pattern, which almost synchronized with the temperature change. The respiration ratio of elevated CO₂ to ambient CO₂ increased gradually from 1.1 to 1.6 until the end of the experiment. Our results indicate that the CO₂ level and the temperature have a strong interactive effect on respiration and suggest that a potential increase in respiration of branches will occur when ambient CO₂ increases.     

Turbulent exchange of CO2 over a broadleaf-Korean pine forest in Changbai Mountain, northeast China

Turbulent exchange of CO₂ was measured continuously via the open-path eddy covariance technique over a broadleaf-Korean pine forest in Changbai Mountain, northeast China. The results show that with near-neutral atmospheric stratification, CO₂ and vertical wind components measured over the forest canopy in the inertial sub-range followed the expected −2/3 power law. The dominant vertical eddy scale was about 100 m. The frequency ranges of eddy contributions to CO₂ fluxes were mostly within 0.01–2.0 Hz. Large eddies with low frequency over the canopy contributed more to CO₂ fluxes than small eddies. The open-path eddy covariance system could satisfy the estimation of turbulent fluxes over the canopy, but the CO₂ fluxes between forest and atmosphere were generally underestimated at night because of the increment non-turbulent processes, suggesting that the CO₂ fluxes estimated under weak turbulence need to be revised correspondingly. __________ Translated from Chinese Journal of Applied Ecology, 2007, 18(5): 951–956 [译自: 应用生态学报]     

Response of five dry tropical tree seedlings to elevated CO2: Impact of seed size and successional status

The impact of seed size and successional status on seedling growth under elevated CO₂ was studied for five dry tropical tree species viz. Albizia procera, Acacia nilotica, Phyllanthus emblica, Terminalia arjuna and Terminalia chebula. Seedlings from large (LS) and small seeds (SS) were grown at two CO₂ levels (ambient and elevated, 700–750 ppm). CO₂ assimilation rate, stomatal conductance, water use efficiency and foliar N were determined after 30 d exposure to elevated CO₂. Seedlings were harvested after 30 d and 60 d exposure periods. Height, diameter, leaf area, biomass and other growth traits (RGR, NAR, SLA, R:S) were determined. Seedling biomass across species was positively related with seed mass. Within species, LS seedlings exhibited greater biomass than SS seedlings. Elevated CO₂ enhanced plant biomass for all the species. The relative growth rate (RGR), net assimilation rate (NAR), CO₂ assimilation rate, R:S ratio and water use efficiency increased under elevated CO₂. However, the positive impact of elevated CO₂ was down regulated beyond 30 d exposure. Specific leaf area (SLA), transpiration rate, stomatal conductance declined due to exposure to elevated CO₂. Fast growing, early successional species exhibited greater RGR, NAR and CO₂ assimilation rate. Per cent enhancement in such traits was greater for slow growing species. The responses of individual species did not follow functional types (viz. legumes, non-legumes). The enhancement in biomass and RGR was greater for large-seeded species and LS seedlings within species. This study revealed that elevated CO₂ could cause large seeded, slow growing and late successional species to grow more vigorously.     

Changes in root growth and relationships between plant organs and root hydraulic traits in American elm (Ulmus americana L.) and red oak (Quercus rubra L.) seedlings due to elevated CO2 level

The relationships between plant organs and root hydrological traits are not well known and the question arises whether elevated CO2 changes these relationships. This study attempted to answer this question. A pseudo-replicated experiment was conducted with two times 24 American elm (Ulmus americana L.) and 23 and 24 red oak (Quercus rubra L.) seedlings growing in ambient CO2 (around 360 μmol·L–1) and 540 ± 7.95 μmol·L–1 CO₂ in a greenhouse. After 71 days of treatment for American elm and 77 days for red oak, 14 American elm and 12 red oak seedlings from each of the two CO2 levels were randomly selected in order to examine the flow rate of root xylem sap, root hydraulic conductance, total root hydraulic conductivity, fine root and coarse root hydraulic conductivity. All seedlings were harvested to investigate total plant biomass, stem biomass and leaf biomass, leaf area, height, basal diameter, total root biomass, coarse root biomass and fine root biomass. The following conclusions are reached: 1) plant organs respond to the elevated CO2 level earlier than hydraulic traits of roots and may gradually lead to changes in hydraulic traits; 2) plant organs have different relationships with hydraulic traits of roots and elevated CO2 changes these relationships; the changes may be of importance for plants as means to acclimatize to changing environments; 3) biomass of coarse roots increased rather more than that of fine roots; 4) Lorentzian and Caussian models are better in estimating the biomass of seedlings than single-variable models.     

Effects of long-term elevated CO<Subscript>2</Subscript> on N<Subscript>2</Subscript>-fixing,denitrifying and nitrifying enzyme activities in forest soils under <Emphasis Type="Italic">Pinus sylvestriformis</Emphasis> in Changbai Mountain

A study was conducted to determine the effects of elevated CO₂ on soil N process at Changbai Mountain in Jilin Province, northeastern China (42°24′N, 128°06′E, and 738 m elevation). A randomized complete block design of ambient and elevated CO₂ was established in an open-top chamber facility in the spring of 1999. Changpai Scotch pine (Pinus sylvestris var. sylvestriformis seeds were sowed in May, 1999 and CO₂ fumigation treatments began after seeds germination. In each year, the exposure started at the end of April and stopped at the end of October. Soil samples were collected in June and August 2006 and in June 2007, and soil nitrifying, denitrifying and N₂-fixing enzyme activities were measured. Results show that soil nitrifying enzyme activities (NEA) in the 5–10 cm soil layer were significantly increased at elevated CO₂ by 30.3% in June 2006, by 30.9% in August 2006 and by 11.3% in June 2007. Soil denitrifying enzyme activities (DEA) were significantly decreased by elevated CO₂ treatment in June 2006 (P < 0.012) and August 2006 (P < 0.005) samplings in our study; no significant difference was detected in June 2007, and no significant changes in N₂-fixing enzyme activity were found. This study suggests that elevated CO₂ can alter soil nitrifying enzyme and denitrifying enzyme activities. Foundation project: This research was supported by the National Natural Science Foundation of China (No. 90411020) and Major State Basic Research Development Program of China (973 Program) (2002CB412502).     

CO_2和O_3浓度升高对森林生态系统影响的研究进展

系统收集和整理了国内外关于CO2和O3复合胁迫对森林影响的研究,从两者的复合胁迫对森林树木的光合作用、地上部分生长、根系生长、土壤环境、种间竞争的影响等方面进行了阐述,并对该领域有待深入研究的方向进行了展望;提出应深入开展对植物地下水平和分子水平的研究,为解决全球气候变化对森林造成的影响提供借鉴,同时为生态系统的管理提供依据。     

Response of seedlings growth of Pinus sylvestriformis to atmospheric CO_2 enrichment in Changbai Mountain

IntroductionGIobaIchangehasbeenoneoftheimpoFtantis-suesandscientistspaycIoseattentiontoit.ThegreatimportanceofforestecosystemisreflectednotonlybytheirhUgebiomass,butaIsobytheirsignifi-cantroIeintheglobaIcarbonbaIance.Howtreesrespondtoclimaticchangesmightbeofgreatsig-nificance.ManystudiesindicatethattherisingatmosphericCo,leveIscanmakeasubstantialeffectonplantgroWthanddevelopment.SomeonethinkcommonlythattherisingCo,levelscanstimuIatepIantgroWthandbiomassproduction,sincephotosynthesisofC…     

Relationships between soil CO2 concentration and CO2 production, temperature, water content, and gas diffusivity: implications for field studies through sensitivity analyses

Soil CO₂ levels reflect CO₂ production and transport in soil and provide valuable information about soil CO₂ dynamics. However, extracting information from soil CO₂ profiles is often difficult because of the complexity of these profiles. In this study, we constructed a simple numerical model that simulated soil CO₂ dynamics and performed sensitivity analyses for CO₂ production rates, soil water content and temperature, and gas diffusivity at the soil surface to clarify the relationships among these parameters. Increased soil surface CO₂ flux did not always coincide with higher soil CO₂ concentrations; increased CO₂ production at shallow depths had little effect on soil CO₂ concentrations, while the opposite may be true for high levels of soil water content. Higher soil CO₂ concentration did not always coincide with greater soil surface CO₂ flux; under high soil water conditions, soil surface CO₂ flux sometimes decreased despite increased soil CO₂ concentration. Increases in soil water content did not always enhance both soil surface CO₂ flux and soil CO₂ concentration. Under high soil water conditions, increases in soil water content could lower soil surface CO₂ flux and increase soil CO₂ concentration. Increases in soil temperature resulted in greater soil surface CO₂ flux and higher soil CO₂ concentration in our simulation (extremely high temperatures were not assumed in this study). Gas diffusivity in very shallow layers did affect, albeit weakly, soil CO₂ concentration. The findings of this study may help direct future observations and aid in the interpretation of their results.     

Birch stands growth increase in Western Siberia

Birch (Betula pendula Roth) growth within the Western Siberia forest-steppe was analyzed based on long-term (1897–2006) inventory data (height, diameter at breast height [dbh], and stand volume). Analysis of biometry parameters showed increased growth at the beginning of twenty-first century compared to similar stands (stands age = 40–60 years) at the end of nineteenth century. Mean height, dbh, and stem volume increased from 14 to 20 m, from 16 to 22 cm, and from ～63 to ～220 m³/ha, respectively. Significant correlations were found between the stands mean height, dbh, and volume on the one hand, and vegetation period length (r_s = 0.71 to 0.74), atmospheric CO₂ concentration (r_s = 0.71 to 0.76), and drought index (Standardized Precipitation-Evapotranspiration Index, r_s = ?0.33 to ?0.51) on the other hand. The results obtained have revealed apparent climate-induced impacts (e.g. increase of vegetation period length and birch habitat drying due to drought increase) on the stands growth. Along with this, a high correlation of birch biometric parameters and [CO₂] in ambient air indicated an effect of CO₂ fertilization. Meanwhile, further drought increase may switch birch stand growth into decline and greater mortality as has already been observed within the Trans-Baikal forest-steppe ecotone.     

长期高浓度CO_2处理对长白赤松土壤硝化酶、反硝化酶和固氮酶活性的影响(英文)

在吉林省长白山地区模拟检测了大气CO2浓度升高对土壤氮循环关键过程的影响。试验采用完全随机区组设计的开顶箱系统模拟环境CO2和高浓度CO2,起始于1999年春。选取长白山特有树种长白松(Pinus sylvestris var.sylvestri-formu),种子播种于1999年5月份,萌芽后开始CO2熏蒸处理。CO2熏蒸处理始于每年4月末止于10月末。分别在2006年6月、8月和2007年6月采集土壤样品,并检测土壤硝化酶(NEA)、反硝化酶(DEA)和固氮酶活性。结果表明,高浓度C02使土壤硝化酶(NEA)活性显著提高,提高幅度2006年6月为30.3%,2006年8月为30.9%,2007年6月为11.3%;土壤反硝化酶活性(DEA)在2006年6月份(P<0.012)和2006年8月份(P<0.005)被C02浓度升高显著抑制;在整个研究过程中没有发现C02浓度升高对固氮酶活性产生显著影响。因此,本研究认为C02浓度升高显著影响了土壤硝化酶(NEA)和反硝化酶活性(DEA)。图3表1参44。     

Development of a CO2 gas analyzer for monitoring soil CO2 concentrations

Measurement of soil CO₂ concentrations is important for investigating the dynamics and diffusion of CO₂ in soil. In this study, we developed a small CO₂ analyzer for measuring in situ-soil CO₂ concentrations. The CO₂ analyzer consists of a module containing an infrared CO₂ gas sensor, a temperature sensor, and a relative humidity sensor. These sensors are installed in a protective box with an air vent, which is suitable for burying in the soil. The output response time of the CO₂ analyzer was 349 s, as evaluated from the phase lag after input of known CO₂ concentrations. This response time is short enough to measure soil CO₂ concentrations, because variations in concentration are slower than the response time of the analyzer. In a field test, we used the CO₂ analyzer to measure soil CO₂ concentrations at five depths (0–50 cm) over 2.5 months. While the CO₂ concentration generally increased with depth, the amplitude of the variation in CO₂ concentration decreased with depth. The phase lag of the variations in soil CO₂ concentration also increased with depth, as did soil temperature. The tests confirm that the CO₂ analyzer is applicable to continuous monitoring of soil CO₂ concentrations.