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1.
Spiraea pubescens, a common shrub in the warm-temperate deciduous forest zone which is distributed in the Dongling Mountain area of Beijing,
was exposed to ambient and enhanced ultraviolet-B (UV-B, 280–320 nm) radiation by artificially supplying a daily dose of 9.4
kJ/m2 for three growing seasons, a level that simulated a 17% depletion in stratospheric ozone. The objective of this study was
to explore the effects of long-term UV-B enhancement on stomatal conductance, leaf tissue δ
13C, leaf water content, and leaf area. Particular attention was paid to the effects of UV-B radiation on water use efficiency
(WUE) and leaf total nitrogen content. Enhanced UV-B radiation significantly reduced leaf area (50.1%) but increased leaf
total nitrogen content (102%). These changes were associated with a decrease in stomatal conductance (16.1%) and intercellular
CO2 concentration/ air CO2 concentration (C
i
/C
a) (4.0%), and an increase in leaf tissue δ
13C (20.5‰), leaf water content (3.1%), specific leaf weight (SLW) (5.2%) and WUE (4.1%). The effects of UV-B on the plant were
greatly affected by the water content of the deep soil (30–40 cm). During the dry season, differences in the stomatal conductance,
δ
13C, and WUE between the control and UV-B treated shrubs were very small; whereas, differences became much greater when soil
water stress disappeared. Furthermore, the effects of UV-B became much less significant as the treatment period progressed
over the three growing seasons. Correlation analysis showed that enhanced UV-B radiation decreased the strength of the correlation
between soil water content and leaf water content, δ
13C, C
i/C
a, stomatal conductance, with the exception of WUE that had a significant correlation coefficient with soil water content.
These results suggest that WUE would become more sensitive to soil water variation due to UV-B radiation. Based on this experiment,
it was found that enhanced UV-B radiation had much more significant effects on morphological traits and growth of S. pubescens than hydro-physiological characteristics.
__________
Translated from Journal of Plant Ecology, 2006, 30(1): 47–56 [译自: 植物生态学报] 相似文献
2.
Four-year-oldPinus sylvestriformis were exposed for four growing seasons in open top chambers to ambient CO2 concentration (approx. 350 μmol·mol−1) and high CO2 concentrations (500 and 700 μmol·mol−1) at Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences at Antu Town, Jilin Province, China
(42°N, 128°E). Stomatal response to elevated CO2 concentrations was examined by stomatal conductance (g
s), ratio of intercellular to ambient CO2 concentration (c
i/c
a) and stomatal number. Reciprocal transfer experiments of stomatal conductance showed that stomatal conductance in high-[CO2]-grown plants increased in comparison with ambient-[CO2]-grown plants when measured at their respective growth CO2 concentration and at the same measurement CO2 concentration (except a reduction in 700 μmol·mol−1 CO2. grown plants compared with plants on unchambered field when measured at growth CO2 concentration and 350 μmol·mol−1CO2). High-[CO2]-grown plants exhibited lowerc
i/c
a ratios than ambient-[CO2]-grown plants when measured at their respective growth CO2 concentration. However,c
i/c
a ratios increased for plants grown in high CO2 concentrations compared with control plants when measured at the same CO2 concentration. There was no significant difference in stomatal number per unit long needle between elevated and ambient CO2. However, elevated CO2 concentrations reduced the total stomatal number of whole needle by the decline of stomatal line and changed the allocation
pattern of stomata between upper and lower surface of needle.
Foundation Item: This research was supported by National Basic Research Program of China (2002CB412502), Project of Key program of the National
Natural Science Foundation of China (90411020) and National Natural Science Foundation of China (30400051).
Biography: ZHOU Yu-mei (1973-), female, Ph. Doctor, assistant research fellow, Institute of Applied Ecology, Chinese Academy of Sciences,
Shenyang 110016, P. R. China.
Responsible editor: Song Funan 相似文献
3.
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 相似文献
4.
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. 相似文献
5.
目的]探究抑制剂对大叶黄杨生长的抑制作用以及对其叶片形态和光合作用的影响,为灌木绿篱的化学修剪提供技术指导。[方法]在北京林业大学林场苗圃采用3种生长抑制剂(多效唑(PP_(333))、三碘苯甲酸(TIBA)以及脱落酸(ABA))对密植成绿篱状的1年生大叶黄杨扦插苗进行叶面喷施,对其生长、叶片形态及光合作用等指标进行测定。[结果]3种抑制剂均有矮化植株、抑制新梢生长的作用,矮化效果最佳、抑制作用最强的为PP_(333),且高浓度PP_(333)对于高生长的抑制作用持效性较长。叶宽、叶厚以及叶面积在短期PP_(333)处理下高于对照。PP_(333)能提高大叶黄杨净光合速率,主要通过增加叶厚、气孔导度、叶肉导度及叶绿素含量来实现,并且PP_(333)使蒸腾速率提高的同时降低了水分利用效率。TIBA有显著减小叶长、叶宽的作用,但能使叶厚增加,且随浓度的增加作用效果增强,主要通过减小叶面积,降低叶肉导度、气孔导度、胞间CO_2浓度及叶绿素含量来降低净光合速率。ABA能增加叶面积(10 mg·L~(-1)处理除外)、叶长以及减小叶片厚度,通过抑制气孔导度、叶肉导度、叶绿素含量降低净光合速率。TI-BA及ABA均通过降低蒸腾速率,使水分利用效率提高。[结论]3种抑制剂均有矮化植株、抑制新梢生长的作用,并且影响叶片发育,进而影响叶片光合作用,且800 mg·L~(-1)的多效唑对大叶黄杨具有较好的正向作用。 相似文献
6.
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 相似文献
7.
Four different kinds of water treatment were applied to examine the photosynthetic characteristics of baldcypress (Taxodium distichum) seedlings in the hydro-fluctuation belt of the Three Gorges Reservoir area. The aim was to shed light on the physio-ecological
adaptation of this species to changing water levels for revegetation purposes. The water treatments were normal growth water
condition (CK), light drought water stress (T1), growth under soil water saturation (T2) and growth with soil submersion (T3).
T3 had the lowest content of photosynthetic pigment; T1 and T2 did not differ from CK in the content of chlorophyll and carotenoid.
The ratio of chlorophyll a to b in the four groups ranged from 2.04 to 2.69 and the ratio of chlorophyll to carotenoid from 3.08 to 4.51. In group T1, the
seedling of baldcypres had lower apparent light use efficiency, lower apparent CO2 use efficiency and a lower net photosynthetic rate, with the net photosynthetic rate 24.9% lower than that of group CK. However,
T2 and T3 did not differ from CK in apparent light use efficiency, apparent CO2 use efficiency and net photosynthetic rate. Water use efficiency of the four treatments consistently increased as treatment
was prolonged; the average water use efficiency of T3 was the lowest while that of CK was the highest. Correlation analysis
showed that the net photosynthetic rate of baldcypress seedlings was positively related to transpiration rate, stomatal conductance,
water use efficiency, apparent light use efficiency and apparent CO2 use efficiency, but highly negatively related to the ratio of chlorophyll a to b. Net photosynthetic rate was not significantly related to the contents of chlorophyll and carotenoid, the ratio of chlorophyll
to carotenoid, relative air humidity and intercellular CO2 concentration. The transpiration rate was positively correlated with stomatal conductance and negatively related to water
use efficiency. The results showed that different water treatments could effectively influence the baldcypress seedlings’
content of photosynthetic pigment, leaf gas exchange and apparent resources use efficiency. The results verified that the
species T. distichum takes on the features of a water-tolerant and hydrophilic plant, which can be considered as one of the species for the building
of a forest protection system for the hydro-fluctuation belt in the Three Gorges Reservoir area. Baldcypress should not be
planted in drought-stricken soils.
__________
Translated from Acta Ecologica Sinica, 2005, 25(8) [译自:生态学报, 2005, 25(8)] 相似文献
8.
Zhibo Ma Shengqing Shi Qinyan Ma Yutao Wang Xingliang Liu 《Frontiers of Forestry in China》2008,3(3):364-368
Responses of the photosynthetic characteristics to variation in CO2 concentration and temperature of Ginkgo biloba, Eucommia ulmoides, Magnolia denudata and Tilia japonica were measured during the peak growing season. The results show that the ambient CO2 concentration could not meet the requirements for photosynthesis of these four species. The optimal temperatures for photosynthesis
were lower than the average daytime air temperature. Hence, the photosynthesis of these four species was restricted by the
low CO2 concentration and high daytime air temperature at the time of measurement. Marked enhancements in the net photosynthetic
rate were found in all four species when the CO2 concentration was doubled. When the dependency on CO2 and temperature were examined simultaneously, it was seen that for increased CO2 concentrations there was a shift in the optimum temperature for M. denudata and T. japonica towards higher temperatures. Due to their independence on CO2 concentrations, this trend could not be found in the G. biloba and E. ulmoides data sets. The stomatal conductance (G
s) was sensitive to a vapor pressure deficit (VPD) which in turn was sensitive to temperature. An increase in temperature would cause the VPD to increase and plants might be assumed to react by reducing their stomatal apertures. The effect on stomatal resistance
would be most significant at high temperatures. The restriction to stomatal conductance for these four species would increase
if CO2 concentrations were elevated at the same temperature.
__________
Translated from Journal of Agricultural University of Hebei, 2006, 29 (6): 39–43 [译自: 河北农业大学学报] 相似文献
9.
The net CO2 assimilation rate, stomatal conductance, RuBPcase (ribulose 1,5-biphosphate carboxylose) activity, dry weight of aboveground
and belowgroud part, plant height, the length and diameter of taproot ofPinus koraiensis seedlings were measured and analyzed after six-week exposure to elevated CO2 in an open-top chamber in Changbai Mountain of China from May to Oct. 1999. Seedlings were planted in four different conditions:
on an open site, control chamber, 500 μL·L−1 and 700 μL·L−1 CO2 chambers. The results showed that the total biomass of the seedlings increased whereas stomatal conductance decreased. The
physiological responses and growth to 500 μL·L−1 and 700 μL·L−1 CO2 varied greatly. The acclimation of photosynthesis was downward to 700 μL·L−1 CO2 but upward to 500 μL·L−1 CO2. The RuBPcase activity, chlorophyll and soluble sugar contents of the seedlings grown at 500 μL·L−1 CO2 were higher than that at 700 μL·L−1 CO2. The concentration 500 μL·L−1 CO2 enhanced the growth of aboveground part whereas 700 μL·L−1 CO2 allocated more carbon to belowground part. Elevated CO2 changed the carbon distribution pattern. The ecophysiological responses were significantly different between plants grown
under 500 μL·L−1 CO2 and 700 μL·L−1 CO2.
Foundation Item: This paper was supported by Chinese Academy of Sciences.
Biography: HAN Shi-jie (1956-), male, Ph. Doctor, Professor in Laboratory of Ecological Process of Trace Substance in Terrestrial Ecosystem,
Institute of Applied Ecology, Chinese Academy of Sciences.
Responsible editor: Chai Ruihai 相似文献
10.
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. 相似文献
11.
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 相似文献
12.
The photosynthetic response of 12-year oldPinus sylvestriformis to elevated CO2 and its influential factors were tested and analyzed in the forest region of Changbai Mountain in 1999. Trees grown at the
natural condition were controlled at three levels of CO2 concentration (350 μL·L−1, 500 μL·L−1 and 700 μL·L−1) by CO2 rich settlement designed by us. Net photosynthetic rates (NPR), temperature, relative humidity, stomatal conductance, intercellular
CO2 concentration and photosynthetic active radiation (PAR) were measured at 6:00, 8:00, 10:00, 14:00, 16:00 and 18:00 hours
a day. Experimental results showed that the NPR ofPinus sylvestriformis increased by 32.6% and 123.0% at 500 μL·L−1 and 700 μL·L−1 CO2 concentration respectively, compared to ambient atmospheric CO2 concentration (350 μL·L−1). The relations between NPR and influential factors, including temperature, relative humidity, intercellular CO2 concentration and photosynthetic active radiation, were analyzed respectively by regression analysis at different CO2 concentrations.
Foundation Item: This project was supported by Chinese Academy of Sciences.
Biography: WANG Chen-rui (1970-), male, Assistant Research Fellow in Institute of Applied Ecology, Chinese Academy of Sciences.
Responsible editor: Chai Ruihai 相似文献
13.
Hermann Rodenkirchen Axel Göttlein Alessandra R. Kozovits Rainer Matyssek Thorsten E. E. Grams 《European Journal of Forest Research》2009,128(2):117-128
Saplings of Fagus sylvatica and Picea abies were grown under conditions of intra and interspecific competition in a 2-year phytotron study under combinations of ambient
and elevated ozone (+O3 which is 2 × O3, but <150 nl l−1) as well as carbon dioxide concentrations (+CO2 which is amb. CO2 + 300 μl CO2 l−1) in a full factorial design. Saplings were analysed for various mineral nutrients in different plant organs as well as biomass
production and crown development. The study was based on the assumption that nutritional parameters important for growth and
competitiveness are affected by stress defence under limiting nutrient supply. The hypotheses tested were (1) that nutrient
uptake-related parameters (a) as well as efficiencies in nutrient use for above-ground competition (b) of beech rather than
spruce are impaired by the exposure to elevated O3 concentrations, (2) that the efficiency in nutrient uptake of spruce is enhanced by elevated CO2 concentrations in mixed culture, and (3) that the ability to occupy above-ground space at low nutrient cost is co-determinant
for the competitive success in mixed culture. Clear nitrogen deficiencies were indicated for both species during the 2-year
phytotron study, although foliar nitrogen-biomass relationships were not so close for spruce than for beech. O3 stress did not impair nutrient uptake-related parameters of beech; thus hypothesis (1a). was not supported. A negative effect
of elevated O3 (under amb. CO2) on the N and P based efficiencies in above-ground space occupation (i.e. lower crown volume per unit of N or P invested
in stems, limbs and foliage) of beech supported hypothesis (1b). It appeared that ozone stress triggered a nutrient demand
for stress defence and tolerance at the expense of above-ground competition (trade-off). Crown volume of beech under O3 stress was stabilized in monoculture by increased nutrient uptake. In general, the +CO2-treatment was able to counteract the impacts of 2 × O3. Elevated CO2 caused lower N and S concentrations in current-year foliage of both tree species, slightly higher macronutrient amounts in
the root biomass of spruce, but did not increase the efficiencies in nutrient uptake of spruce in mixed culture. Therefore
hypothesis (2) was not supported. At the end of the experiment spruce turned out to be the stronger competitor in mixed culture
as displayed by its higher total shoot biomass and crown volume. The amounts of macronutrients in the above-ground biomass
of spruce individuals in mixed culture distinctly exceeded those of beech, which had been strongly reduced by interspecific
competition. The superior competitiveness of spruce was related to higher N and P-based efficiencies in above-ground space
occupation as suggested in hypothesis (3).
This article belongs to the special issue “Growth and defence of Norway spruce and European beech in pure and mixed stands”. 相似文献
14.
温度对大叶桃花心木(Swietenia macrophylla King)幼苗叶片的光合影响 总被引：2，自引：0，他引：2
本文研究了大叶桃花心木（Swietenia macrophylla King）一年生幼苗在经过夜温处理后的光响应曲线和在饱和光强下的CO2反应曲线.结果表明:在大气CO2浓度下,叶片的最佳光合作用温度在25-31℃之间,而在饱和CO2浓度下为31-35℃.在25℃以下光合速率开始降低,主要是由于羧化效率的降低,而当温度超过31℃时,光合速率下降,是因为羧化效率的降低和呼吸速率的增加.CO2浓度对光合的促进作用在低温下受到抑制,这意味着未来在CO2浓度增高的情况下,高浓度的CO2对热带常绿植物光合的促进在冬天低温情况下表现不十分明显.图4参23. 相似文献
15.
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 相似文献
16.
Effect of elevated ambient CO2 concentration on water use efficiency of Pinus sylvestriformis 总被引：1，自引：0，他引：1
IntroductionEvidencefrommanystudiesshowsthattheconcentrationofatmosphericCO,isdramaticallyraisingandadoubIingofthepresentCO,concentrationwouIdoccurduringthelasthaIfofthenextcentury.Therisingofatmospheric.CO,concentrationisstrongIycorrelatedwiththeincreaseinglobaIconsumptionoffossiIfueIsandaIsoaffectedsignificantIybytheclearingofforest(Bazzaz199o).PfantsgrowingatvariousambientconcentrationofCo,showgreatdifferences,includingtheprocessesofgrowthandphysiology.Photosynthesisandtran-spiration… 相似文献
17.
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. 相似文献
18.
The light response curve and the intercellular CO2 concentration response curve of CO2 assimilation rate were investigated together with the light conditions at the four different heights within the beech crown
from 1995 to 1997 on Mt. Fuji in Japan. On the seasonal fluctuation, the CO2 assimilation rate at light saturated condition increased rapidly in May, and attained to the maximum between the end of June
and July, thereafter, slightly decreased until the middle of August and rapidly decreased in September and October. The daily
sum of photosynthetic photon flux density attenuated with deeping within the crown, and particularly, the relative value on
2nd position dropped to only 30%. TheA
max decreased from 10 to 5μmol m−2 s−1, approximately, with deeping within the crown. The light saturation point, quantum yield, light compensation point and dark
respiration rate also varied with deeping. These results suggest that the photosynthetic properties vary gradually from sun
to shade leaves along the light attenuation within a beech crown. At light saturated condition, the stomatal conductance and
mesophyll conductance were strongly correlated withA
max among the four different heights (r > 0.96, respectively). TheC
i/C
a ratio was around 0.8, and there were no remarkable differences among the four different heights. These results suggest that
the vertical gradient ofA
max depends on the variation of mesophyll conductance. The stomatal conductance may be also one of the major factor in the vertical
gradient ofA
max. However the intercellular CO2 concentration doesn’t influence the vertical gradient ofA
max within the crown.
This work is supported by the Sasagawa Scientific Research Grant from The Japan Science Society and Grant-in-Aid for Scientific
Research (C). 相似文献
19.
Forest soil is a huge reserve of carbon in the biosphere. Therefore to understand the carbon cycle in forest ecosystems, it
is important to determine the dynamics of soil CO2 efflux. This study was conducted to describe temporal variations in soil CO2 efflux and identify the environmental factors that affect it. We measured soil CO2 efflux continuously in a beech secondary forest in the Appi Highlands in Iwate Prefecture for two years (except when there
was snow cover) using four dynamic closed chambers that automatically open after taking measurements. Temporal changes in
soil temperature and volumetric soil water content were also measured at a depth of 5 cm. The soil CO2 efflux ranged from 14 mg CO2 m−2 h−1 to 2,329 mg CO2 m−2 h−1, the peak occurring at the beginning of August. The relationship between soil temperature and soil CO2 efflux was well represented by an exponential function. Most of temporal variation in soil CO2 efflux was explained by soil temperature rather than volumetric soil water content. The Q
10 values were 3.7 ± 0.8 and estimated annual carbon emissions were 837 ± 210 g C m−2 year−1. These results provide a foundation for further development of models for prediction of soil CO2 efflux driven by environmental factors. 相似文献
20.
外源糖溶液和高浓度CO2处理对白桦叶片糖和蛋白质含量的影响 总被引：1，自引：0，他引：1
3年生白桦同时接受3种外源糖溶液(蔗糖、果糖、葡萄糖)和3种高浓度CO2(700、1400、2100μL·μL-1CO2)处理.处理1个月后,测定了叶片的总糖、蔗糖、果糖和蛋白质含量.结果表明:在700μL·L-1和1400μL·L-1 CO2下,外源糖溶液增加了叶片的可溶性糖和蛋白质含量,其中外源蔗糖的效果最好:外源糖溶液与2100μL·L-1CO2结合,会抑制叶片积累总糖和蛋白质:在700μL·L-1和1400μL·L-1CO2下,喷施葡萄糖、果糖的叶片在蛋白质含量上没有明显差别:同700、1400μL·L-1CO2相比,除喷施果糖植株外,2100μL·L-1 CO2明显增加了叶片的总糖、蔗糖、果糖和蛋白质含量:在喷施同种外源糖溶液的情况下,叶片的糖含量与CO2浓度呈正相关性.图6参7. 相似文献