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1.
The natural geographical occurrence, carbon assimilation, and structural and biochemical diversity of species with C4 photosynthesis in the vegetation of Mongolia was studied. The Mongolian flora was screened for C4 plants by using 13C/12C isotope fractionation, determining the early products of 14CO2 fixation, microscopy of leaf mesophyll cell anatomy, and from reported literature data. Eighty C4 species were found among eight families: Amaranthaceae, Chenopodiaceae, Euphorbiaceae, Molluginaceae, Poaceae, Polygonaceae,
Portulacaceae and Zygophyllaceae. Most of the C4 species were in three families: Chenopodiceae (41 species), Poaceae (25 species)
and Polygonaceae, genus Calligonum (6 species). Some new C4 species in Chenopodiaceae, Poaceae and Polygonaceae were detected. C4 Chenopodiaceae species make up 45% of the total chenopods and are very important ecologically in saline areas and in cold
arid deserts. C4 grasses make up about 10% of the total Poaceae species and these species naturally concentrate in steppe zones. Naturalized
grasses with Kranz anatomy,of genera such as Setaria, Echinochloa, Eragrostis, Panicum and Chloris, were found in almost all the botanical-geographical regions of Mongolia, where they commonly occur in annually disturbed
areas and desert oases. We analyzed the relationships between the occurrence of C4 plants in 16 natural botanical-geographical regions of Mongolia and their major climatic influences. The proportion of C4 species increases with decreasing geographical latitude and along the north-to-south temperature gradient; however grasses
and chenopods differ in their responses to climate. The abundance of Chenopodiaceae species was closely correlated with aridity,
but the distribution of the C4 grasses was more dependent on temperature. Also, we found a unique distribution of different C4 Chenopodiaceae structural and biochemical subtypes along the aridity gradient. NADP-malic enzyme (NADP-ME) tree-like species
with a salsoloid type of Kranz anatomy, such as Haloxylon ammodendron and Iljinia regelii, plus shrubby Salsola and Anabasis species, were the plants most resistant to ecological stress and conditions in highly arid Gobian deserts with less than
100 mm of annual precipitation. Most of the annual C4 chenopod species were halophytes, succulent, and occurred in saline and arid environments in steppe and desert regions. The
relative abundance of C3 succulent chenopod species also increased along the aridity gradient. Native C4 grasses were mainly annual and perennial species from the Cynodonteae tribe with NAD-ME and PEP-carboxykinase (PEP-CK) photosynthetic
types. They occurred across much of Mongolia, but were most common in steppe zones where they are often dominant in grazing
ecosystems.
Received: 17 March 1999 / Accepted: 1 November 1999 相似文献
2.
C4 photosynthesis, atmospheric CO2, and climate 总被引:22,自引:0,他引:22
The objectives of this synthesis are (1) to review the factors that influence the ecological, geographical, and palaeoecological
distributions of plants possessing C4 photosynthesis and (2) to propose a hypothesis/model to explain both the distribution of C4 plants with respect to temperature and CO2 and why C4 photosynthesis is relatively uncommon in dicotyledonous plants (hereafter dicots), especially in comparison with its widespread
distribution in monocotyledonous species (hereafter monocots). Our goal is to stimulate discussion of the factors controlling
distributions of C4 plants today, historically, and under future elevated CO2 environments. Understanding the distributions of C3/C4 plants impacts not only primary productivity, but also the distribution, evolution, and migration of both invertebrates and
vertebrates that graze on these plants. Sixteen separate studies all indicate that the current distributions of C4 monocots are tightly correlated with temperature: elevated temperatures during the growing season favor C4 monocots. In contrast, the seven studies on C4 dicot distributions suggest that a different environmental parameter, such as aridity (combination of temperature and evaporative
potential), more closely describes their distributions. Differences in the temperature dependence of the quantum yield for
CO2 uptake (light-use efficiency) of C3 and C4 species relate well to observed plant distributions and light-use efficiency is the only mechanism that has been proposed
to explain distributional differences in C3/C4 monocots. Modeling of C3 and C4 light-use efficiencies under different combinations of atmospheric CO2 and temperature predicts that C4-dominated ecosystems should not have expanded until atmospheric CO2 concentrations reached the lower levels that are thought to have existed beginning near the end of the Miocene. At that time,
palaeocarbonate and fossil data indicate a simultaneous, global expansion of C4-dominated grasslands. The C4 monocots generally have a higher quantum yield than C4 dicots and it is proposed that leaf venation patterns play a role in increasing the light-use efficiency of most C4 monocots. The reduced quantum yield of most C4 dicots is consistent with their rarity, and it is suggested that C4 dicots may not have been selected until CO2 concentrations reached their lowest levels during glacial maxima in the Quaternary. Given the intrinsic light-use efficiency
advantage of C4 monocots, C4 dicots may have been limited in their distributions to the warmest ecosystems, saline ecosystems, and/or to highly disturbed
ecosystems. All C4 plants have a significant advantage over C3 plants under low atmospheric CO2 conditions and are predicted to have expanded significantly on a global scale during full-glacial periods, especially in
tropical regions. Bog and lake sediment cores as well as pedogenic carbonates support the hypothesis that C4 ecosystems were more extensive during the last glacial maximum and then decreased in abundance following deglaciation as
atmospheric CO2 levels increased.
Received: 12 February 1997 / Accepted: 20 June 1997 相似文献
3.
Abstract In this study the contribution of climatic factors and phylogenetic relationships affecting the geographical distribution of C3 and C4 genera of the Cyperaceae in South Africa was investigated. The δ13C values of herbarium specimens of 68 southern African species from 22 genera and eight tribes were used to assign the species to either the C3 or C4 photosynthetic pathway. Geographical distribution data for the Cyperaceae were used to investigate relationships between climatic factors and the number of species and proportional abundance of C4 species per region. The number of Cyperaceae species per 2° × 2° square across South Africa varied from less than five in the north‐western regions to more than 15 in the south‐western and north‐eastern regions of South Africa where rainfall exceeds 800 mm y‐1. Of the 68 species investigated, 28 had C4 photosynthesis and these were scattered among nine genera of four tribes (Cypereae, Scirpeae, Abildgaardieae and Rhyncosporeae). The proportional abundance of C4 species ranged from 14% in the winter rainfall regions of the south‐west of South Africa to 67% in the summer rainfall areas of the north‐east. The geographical distribution of species was related to their phylogenetic position such that the distributions of C3 and C4 species in Cypereae, Scirpeae and Schoeneae was quite distinct. Linear regression analysis showed that the transition temperatures (equal C3 and C4 species numbers) for the Cyperaceae were different to those obtained for the Poaceae from the same region. No strong relationships were found between the proportional abundance of C4 species and other climate factors such as altitude and rainfall. Our analysis of the current geographical distribution of C4 Cyperaceae in southern Africa in a phylogenetic context suggests that the ecological advantages conferred by the C4 pathway differ amongst the different plant groups. 相似文献
4.
Occurrence and ecological characteristics of C4 dicot and Cyperaceae species in the Hungarian flora 总被引:1,自引:0,他引:1
The non-graminaceous wild flora of Hungary was screened for C4 plants by using the stable carbon isotope ratio, the leaf anatomy and the photosynthetic carbon dioxide compensation concentration
to determine the photosynthetic pathway type. On the whole, 31 C4 species (native or naturalized) were found in the Amaranthaceae, Chenopodiaceae, Cyperaceae, Euphorbiaceae, Portulacaceae and Zygophyllaceae families. Together with the 26 C4 grass species (Poaceae) reported earlier (Kalapos 1991), a total of 57 wild C4 species occur in Hungary, which forms 2.6 % of the country's angiosperm flora. This figure is somewhat higher than what was
expected on climatic grounds, a fact probably due to certain edaphic conditions favouring C4 plant growth. In Hungary, the C4 species are predominantly annuals growing in open habitats such as dry grasslands, inland saline areas, temporarily exposed
riverbeds and disturbed sites. In comparison with C3 plants, the C4 species have higher temperature and light preferences, and their phenology lags behind that of the C3 plants. These differences might account for C4 plants being usually excluded from productive biotopes in Hungary, where the C3 canopy may become closed during the growing season before C4 plants can start their ontogenetic development. Ecological properties of C3 and C4 plants differ considerably in the Cyperaceae, but much less in the Chenopodianceae family. Among C4 annuals naturalized aliens are common, most of which colonized hungary in the last two centuries. Increasing preponderance
of
C4 plants is anticipated in the future as a consequence of possible climate changes and the ever increasing human impact on
terrestrial vegetation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
Yanis Bouchenak‐Khelladi A. Muthama Muasya H. Peter Linder 《Botanical journal of the Linnean Society. Linnean Society of London》2014,175(1):4-16
Poales represents more than one‐third of all monocotyledons (c. 20 000 species in 16 families) and constitutes a microcosm of the angiosperms. The extreme variation in species richness among the families of Poales is still not understood: Poaceae includes ~10 000 species, whereas six families have fewer than ten species. Here, using the largest phylogenetic analysis of Poales to date, molecular dating, ancestral reconstructions and diversification analyses, we develop a macro‐evolutionary and macro‐ecological approach to seek correlates for changing diversification patterns. We show that the poalean families diverged in the Late Cretaceous, a time of high levels of CO2 and high rainfall. Our habitat reconstructions indicate that Poales inhabited open and dry habitats in this environment. We also demonstrate that lineages with CO2‐concentrating mechanisms inhabiting dry and open environments exhibited higher diversification rates than C3, shade and wet lineages. CO2‐concentrating mechanisms counteract the effects of low atmospheric CO2 and reduce phototranspiration. It is believed that the parallel evolution of C4 and CAM (Crassulacean acid metabolism) photosynthesis in Poaceae, Cyperaceae and Bromeliaceae is an adaptation to changes in atmospheric CO2 concentrations. Combinations of extrinsic and intrinsic factors might have played a role in shifts in diversification rates and may explain the variation in species richness in Poales. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 4–16. 相似文献
6.
Background
Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) catalyses the key reaction in the photosynthetic assimilation of CO2. In C4 plants CO2 is supplied to Rubisco by an auxiliary CO2-concentrating pathway that helps to maximize the carboxylase activity of the enzyme while suppressing its oxygenase activity. As a consequence, C4 Rubisco exhibits a higher maximum velocity but lower substrate specificity compared with the C3 enzyme. Specific amino-acids in Rubisco are associated with C4 photosynthesis in monocots, but it is not known whether selection has acted on Rubisco in a similar way in eudicots.Methodology/Principal Findings
We investigated Rubisco evolution in Amaranthaceae sensu lato (including Chenopodiaceae), the third-largest family of C4 plants, using phylogeny-based maximum likelihood and Bayesian methods to detect Darwinian selection on the chloroplast rbcL gene in a sample of 179 species. Two Rubisco residues, 281 and 309, were found to be under positive selection in C4 Amaranthaceae with multiple parallel replacements of alanine by serine at position 281 and methionine by isoleucine at position 309. Remarkably, both amino-acids have been detected in other C4 plant groups, such as C4 monocots, illustrating a striking parallelism in molecular evolution.Conclusions/Significance
Our findings illustrate how simple genetic changes can contribute to the evolution of photosynthesis and strengthen the hypothesis that parallel amino-acid replacements are associated with adaptive changes in Rubisco. 相似文献7.
Russell K. Monson Robert O. Littlejohn Jr. George J. Williams III 《Photosynthesis research》1982,3(2):153-159
The quantum yield for CO2 uptake was measured in C3 and C4 monocot species from several different grassland habitats. When the quantum yield was measured in the presence of 21% O2 and 340 cm3 m-3 CO2, values were very similar in C3 monocots, C3 dicots, and C4 monocots (0.045–0.056 mole CO2 · mole-1 quanta absorbed). In the presence of 2% O2 and 800 cm3 m-3 CO2, enhancements of the quantum yield values occurred for the C3 plants (both monocots and dicots), but not for C4 monocots. A dependence of the quantum yield on leaf temperature was observed in the C3 grass, Agropyron smithii, but not in the C4 grass, Bouteloua gracilis, in 21% O2 and 340 cm3 m-3 CO2. At leaf temperatures between 22–25°C the quantum yield values were approximately equal in the two species. 相似文献
8.
We used comparative methods that account for the phylogenetic correlations among species to test hypotheses about the community of gall-inducing insects on dicotyledonous and monocotyledonous plants and woody and herbaceous angiosperms in the UK. We found that the species richness of gall-inducing insects on dicots was greater than on monocots and that the odds of a dicot having an associated gall-inducing insect is 42% higher than for a monocot. Woody angiosperms have higher species richness of associated gall-inducing insects than do herbaceous angiosperms. Furthermore, using a Monte Carlo analysis we found that attacks by gall-inducing insects on monocot families were phylogenetically clustered in the order Poales, particularly within the grass family Poaceae. We suggest that the higher risk of attack on dicots and higher species richness of gall-inducing insects on woody angiosperms, which are exclusively dicots, arises because of differences in the abundance or susceptibility of dicot meristems to attack by gall-inducing insects. Architectural and anatomical differences between monocots and dicots that give rise to differences in meristem abundance and anatomy appear to play an important role in determining the occurrence and richness of associated gall-inducing insects on host plants. 相似文献
9.
Summary The nature of the photosynthetic pathways of Cyperaceae found in Japan were investigated on the basis of Kranz anatomy, the CO2 compensation concentration and previously reported data. Among 301 species (96% of all cyperaceous species recorded in the region), 58 species were classified as being C4 plants. These C4 species were scattered among the tribes Fimbristylideae, Lipocarpheae, Cypereae and Rhynchosporeae in the subfamily Cyperoideae. The genera Cyperus, Eleocharis and Rhynchospora included, in Japan, both C3 and C4 species within a single genus. Using these data, an analysis was made of the ecological characteristics and geographical distribution of the C3 and C4 species in Japan. Although cyperaceous species grow in markedly different environments, the majority were found in wet and aquatic areas (61%) or shaded areas, such as forest floors (20%). Most of the C3 species were also hygrophytes (58%) and forest-living species (25%), and C3 species growing in mesic and dry areas were relatively rare. The C4 species inhabited wet and aquatic (75%), mesic (13%) and dry areas (6%) and showed marked ecological characteristics with respect to soil-moisture conditions, unlike other C4 plants, although they were absent from shaded habitats. In order to determine the climatic factors that influence the relative floristic abundance of C3 and C4 members of the Cyperaceae in Japan, the ratios of number of C4 species to the total number of members of Cyperaceae (C4 percentage) in 16 representative locales were examined in terms of various climatic variables. There were strong positive correlations between the C4 percentage and temperature. Among the C3 groups of three subfamilies, there were different distributional trends for various temperature regimes. The C3 subfamily Caricoideae increased its relative contribution to the cyperaceous flora with a decrease in mean annual temperature, while the C3 subfamily Sclerioideae exhibited the opposite pattern. The C3 group of the subfamily Cyperoideae did not show any marked change in pattern along temperature gradients, unlike the two other C3 subfamilies, and seemed to be heterogeneous in terms of its response to temperature. The relationships between the C4 biochemical subtypes and ecological characteristics are also discussed. 相似文献
10.
为揭示不同地区禾本科C3与C4植物花果期受气候因子的影响,以广东省和内蒙古自治区分别代表南亚热带和北温带地区,从植物志中分别获得两地395和265种禾本科草本植物的3个花果期特征(始花期、末花果期和生殖期长),比较开花物候的差异,并通过一般线性模型探究其与气候因子(年均温与年均降水量)的相关性。结果表明,南亚热带与北温带地区C3植物的始花期均比C4植物早。两地C4共有种在南亚热带地区具有更早的始花期、更晚的末花果期和更长的生殖期,而C3共有种的末花果期在两地无显著差异,但在南亚热带地区始花期更早,生殖期更长。随年均温升高,北温带地区禾本科植物的始花期提前,而南亚热带地区则延后;随年均降水量升高,两地禾本科植物始花期与末花果期均延迟;禾本科植物生殖期长与年均温和年均降水量均不存在相关性。跨地区分析表明,末花果期、生殖期长与年均温和年均降水量均正相关,而与始花期不相关。禾本科C3植物比C4植物对地区间气候差异响应更敏... 相似文献
11.
Phosphorus responses of C3 and C4 species 总被引:2,自引:0,他引:2
An hypothesis was formulated that phosphorus (P) partitioningin tissues of C4 leaves would permit C4 plants to resist P deficiencybetter than C3 plants. To test this hypothesis, 12 C3, C4, andC3C4 intermediate species were grown at adequate, deficient,and severely deficient P supply in a solid-phase-buffered sandculture system to characterize photosynthetic and growth responses.Species differed considerably in response to P stress. The growthof C3 species was more sensitive to P supply than C4 species,but C3 and C4 species had similar photosynthetic P use efficiency,and C4 species did not have low leaf P content, contrary toour hypothesis. In fact, leaf photosynthetic rates were notcorrelated with growth responses. Moncots had lower leaf P contentand better maintenance of leaf production under P stress thandicots, because of greater inhibition of branching (dicots)than of tillering (monocots). The most P efficient species inthis survey was Brachiaria, a C4 monocot that increased rootbiomass allocation under stress while maintaining P allocationto the shoot. It is concluded that C4 species are not inherentlymore P efficient than C3 species, but that monocots are moreP efficient than dicots, because of contrasting P and biomassallocation under stress. Key words: Phosphorus deficiency, C3 plants, C4 plants, growth response 相似文献
12.
Yuzhen Ma Kam-biu Liu Zhaodong Feng † Yanli Sang Wei Wang Aizhi Sun 《Journal of Biogeography》2008,35(8):1512-1532
Aim This modern pollen‐rain study documents the spatial and quantitative relationships between modern pollen and vegetation in Mongolia, and explores the potential for using this relationship in palaeoclimatic reconstructions. Location East‐central Mongolia. Methods We collected 104 pollen surface samples along a south–north transect across five vegetation zones in Mongolia. Discriminant analysis was used to classify the modern pollen spectra into five pollen assemblages corresponding to the five vegetation zones. Hierarchical cluster analysis was used to divide the main pollen taxa into two major groups and seven subgroups representing the dry and moist vegetation types and the main vegetation communities within them. Results Each vegetation zone along the transect can be characterized by a distinctive modern pollen assemblage as follows: (1) desert zone: Chenopodiaceae–Zygophyllaceae–Nitraria–Poaceae pollen assemblage; (2) desert‐steppe zone: Poaceae–Chenopodiaceae pollen assemblage; (3) steppe zone: Artemisia–Aster‐type–Poaceae–Pinus Haploxylon‐type pollen assemblage; (4) forest‐steppe zone: Pinus Haploxylon‐type–Picea–Artemisia–Betula, montane forb/shrub and pteridophyte pollen assemblage; and (5) mountain taiga zone: Pinus Haploxylon‐type–Picea–Poaceae–Cyperaceae, montane forb/shrub and Pteridophyte pollen assemblage. Main conclusions Based on the ratio between the major pollen taxon groups and subgroups, we propose two pollen–climate indices that represent the precipitation and temperature conditions in the study region. When plotted along our south–north transect, the moisture indices (M) and temperature indices (T) mimic the regional gradients of precipitation and temperature across Mongolia very closely. These pollen–climate indices can be used for palaeoclimatic reconstruction based on fossil pollen data. 相似文献
13.
Guard cells of plants representing 18 species were assayed qualitatively for potential to conduct photosynthetic linear electron transport. These plants included C3 pteridophytes, C3 and C4 monocots, and C3, C4, and Crassulacean acid metabolism dicots. By use of a microfluorospectrophotometer, guard cell samples in epidermal peels were isolated optically. Chlorophyll fluorescence was monitored from the onset of excitation light. For guard cells of all these species, fluorescence intensity increased during illumination. When samples were preincubated with 3-(3,4-dichlorophenyl)-1,1-dimethylurea, diuron, however, there was a more rapid increase in fluorescence. These results indicate that all tested guard cells conduct photosynthetic electron transport through the reaction center of photosystem II. 相似文献
14.
Comparative Studies on Plastoquinones. III. Distribution of Plastoquinones in Higher Plants 总被引:4,自引:4,他引:0
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The distribution of plastoquinones A 45, B and C was studied in representatives from 34 different plant families beginning with liverworts and mosses to higher plants. All of these species, including many monocots and dicots, contained significant amounts of the 3 quinones. Two species of Aesculus contained plastoquinone A 20 in addition to plastoquinone A 45, B, and C. Many dicots, such as Aesculus, watermelon, tobacco and tomato accumulated increasing quantities of plastoquinones A and C1-C4 during the growing season. The concentrations of plastoquinones B and C5-C6 tended to remain at a constant low level during the season (<0.01 μmole per mg chlorophyll). Preliminary studies with bean plants (Vicia faba and Phaseolus sp.) indicate that the levels of quinones varied little under different growth conditions (day length and temp.) although Vicia faba tended to have higher PQ A values with increased temperature. 相似文献
15.
Modern pollen spectra can improve the interpretation of fossil pollen records used to reconstruct past vegetation, climate and human impacts. It is important, therefore, to carefully examine the relationships between modern pollen spectra, vegetation, climate and human activity. Here, we present the results of an analysis of the pollen spectra of 143 surface pollen samples from farmland, wasteland, desert, steppe/meadow, forest and river valley along a transect from Lanzhou to Urumqi, in northwestern China. The modern pollen assemblages are mainly composed of Amaranthaceae, Artemisia, Poaceae, Asteraceae, Ephedra and Nitraria. The results indicate that in general the surface pollen assemblages of different vegetation types reliably represent the modern vegetation in terms of the composition of the main taxa and the dominant types. Farmland is dominated by cereal-type (≥?15%) and Amaranthaceae (≥?20%), while the pollen assemblages of wasteland (i.e. the vegetation immediately surrounding farmland) are mainly composed of Amaranthaceae (≥?25%), Artemisia (≥?20%), Poaceae (≥?10%), Asteraceae (≥?5%) and Cyperaceae (≥?5%). Amaranthaceae (≥?45%) and Ephedra (≥?10%) are the most important taxa in desert, and Cyperaceae (≥?35%) and Thalictrum (≥?2%) are the dominant pollen types in steppe/meadow. Forest and river valley samples are characterized by high frequencies of Picea (≥?10%) and Cyperaceae (≥?20%). Both constrained and partial canonical ordination techniques (RDA and partial RDA) of the main pollen types and environmental variables show that the modern pollen spectra are primarily controlled by mean annual precipitation (MAP). Cyperaceae, Thalictrum and Brassicaceae are positively correlated with MAP and negatively correlated with mean July temperature (TJuly), while the representation of certain other types, such as Amaranthaceae, Ephedra and Nitraria, is negatively correlated with MAP and positively correlated with TJuly. The Human Influence Index (HII) is significantly correlated with cereal-type pollen, and it can also differentiate human-influenced and natural vegetation. Our results provide a basis for improving the interpretation of fossil pollen records from arid northwestern China and similar regions. 相似文献
16.
Feng Ying Wen Zhi Bin Gulnur Sabirhazi Wang Xi Yong 《Contemporary Problems of Ecology》2014,7(3):301-307
The paper analyses total of 58 samples representing 32 species of the 14 genera of shrub plant of the carbon isotope composition in Xinjiang representatives of Chenopodiaceae and a detailed discussion on the various factors that can influence them. The value of 38 samples fall between ?14.88‰ and ?11.55‰ with a mean of ?13.34‰, and values of 20 samples between ?27.93‰ and ?22.877‰ with a mean of ?25.38‰. So we obtained a total of 21 of C4 species (59.4%) and 11 of C3 species (40.6%) from 32 species studied Chenopodiaceae of shrubs plant. Then the relationship of plant-carbon-isotope and environmental factors has been analyzed. The results showed that the importance environmental factors for the δ13C-value of the Shrubs was annual precipitation (0.78) > temperature (0.66) > elevation (0.55). The three principal components has important factors to influence on C3/C4 shrub plant distribution. Environmental conditions play significant roles in the distribution and ecophysiological features of different photosynthetic types and even change the photosynthetic pathways. On the other hand, such as geographic location, Sunshine duration, evaporation capacity are more or less correlation with δ13C values, however, they would be interfered by annual precipitation. Desert plants to adapt to drought conditions by increasing water use efficiency (WUE) strategy. In short, plant physiology function is sensitive and timely to adapt environmental change. 相似文献
17.
The quantum yield for CO2 uptake was measured on a number of C3 and C4 monocot and dicot species. Under normal atmospheric conditions (330 microliters per liter CO2, 21% O2) and a leaf temperature of 30°C, the average quantum yields (moles CO2 per einstein) were as follows: 0.052 for C3 dicots, 0.053 for C3 grasses, 0.053 for NAD-malic enzyme type C4 dicots, 0.060 for NAD-malic enzyme type C4 grasses, 0.064 for phosphoenolpyruvate carboxykinase type C4 grasses, 0.061 for NADP-malic enzyme C4 dicots, and 0.065 for NADP-malic enzyme type C4 grasses. The quantum yield under normal atmospheric conditions was temperature dependent in C3 species, but apparently not in C4 species. Light and temperature conditions during growth appeared not to influence quantum yield. The significance of variation in the quantum yields of C4 plants was discussed in terms of CO2 leakage from the bundle sheath cells and suberization of apoplastic regions of the bundle sheath cells. 相似文献
18.
Distribution of biomass of species differing in photosynthetic pathway along an altitudinal transect in southeastern wyoming grassland 总被引:4,自引:1,他引:4
Summary Based on the physiological characteristics and responses of C3, C4, and CAM plants to environmental factors, it is generally predicted that C4 and CAM plants will become more abundant with increasing temperature and decreasing precipitation. To test this prediction, the relative contribution of each photosynthetic type to total plant community biomass was examined at seven study areas along an altitudinal transect in southeastern Wyoming grassland. In going from high (2,652 m) to low (1,405 m) elevation along this transect, mean annual temperature increased and annual precipitation decreased.The percentage of C4 biomass composing each study area decreased with increasing elevation, while the percentage of C3 biomass increased. All elevations had a significantly higher percentage of C4 biomass in August than in June, reflecting the warm season growth characteristic of C4 plants. Regressions of relative abundance of photosynthetic types on climatic variables showed that both mean annual temperature and annual precipitation were equally reliable as predictors of C3–C4 biomass, although we feel that temperature is of primary importance in explaining our observations. CAM species were present at all elevations, but showed no trends in biomass distribution with respect to elevation. 相似文献
19.
The natural occurrence and altitudinal pattern of species with C4 photosynthesis were investigated on Qinghai Plateau, Qinghai province by using stable carbon isotopes in plant leaves and
using additional data from references. A total of 58 species belonging to 10 families and 34 genera were identified using
C4 photosynthetic pathway, which is only 1.66 % of total 3 500 plant species in Qinghai province. The leading two families,
i.e. Gramineae (23 species) and Chenopodiaceae (22 species) contain 77.6 % of all C4 plants in the studied area. The number of C4 species increased from 1 600 to 2 400 m a.s.l. and then decreases quickly till 4 400 m a.s.l. with one half of C4 species distributing from 2 200 to 2 800 m a.s.l. (48 %). Eight plant species were found above 4 000 m a.s.l., but the distribution
of these species is limited to the south of Qinghai province (low latitude area) where annual mean temperature is above 0
°C, suggesting that low temperature may generally limit the distribution of C4 plants. 相似文献
20.
A checklist of the currently-known C4 species which occur in Europe was compiled, and the number of these found in European territories was ascertained. Their contribution to the local floras range from 4.35% in the Azores to 0% in Svalbard. Subsequently, a stepwise multiple regression analysis was used to correlate the relative abundances of four subdivisions of C4 species with climatic variables derived for each territory from meteorological tables. The four subdivisions were: (a) total number of C4 species; (b) number of native C4 species; (c) C4 monocots and (d) C4 dicots. These values were expressed as percentages of either the total flora, (a), or the native flora ((b), (c) and (d)) for the regressions. The abundance of each C4 subdivision was found to be strongly correlated with temperature, and to a lesser extent, negatively with precipitation. Habitat information about the European C4 species was also analysed and it was concluded that their apparent preference for maritime and ruderal habitats indicates some form of competitive advantage of the pathway under saline or disturbed conditions. A small number of European C4 species was identified whose distribution appears to be anomalous with respect to temperature and/or soil moisture content.Nomenclature follows Tutin et al. Flora Europaea. 相似文献