首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The influence of ontogeny, light environment and species on relationships of relative growth rate (RGR) to physiological and morphological traits were examined for first-year northern hardwood tree seedlings. Three Betulaceae species (Betula papyrifera, Betula alleghaniensis and Ostrya virginiana) were grown in high and low light and Quercus rubra and Acer saccharum were grown only in high light. Plant traits were determined at four ages: 41, 62, 83 and 104 days after germination. In high light (610 mol m–2 s–1 PPFD), across species and ages, RGR was positively related to the proportion of the plant in leaves (leaf weight ratio, LWR; leaf area ratio, LAR), in situ rates of average canopy net photosynthesis (A) per unit mass (Amass) and per unit area (Aarea), and rates of leaf, stem and root respiration. In low light (127 mol m–2 s–1 PPFD), RGR was not correlated with Amass and Aarea whereas RGR was positively correlated with LAR, LWR, and rates of root and stem respiration. RGR was negatively correlated with leaf mass per area in both high and low light. Across light levels, relationships of CO2 exchange and morphological characteristics with RGR were generally weaker than within light environments. Moreover, relationships were weaker for plant parameters containing a leaf area component (leaf mass per area, LAR and Aarea), than those that were solely mass-based (respiration rates, LWR and Amass). Across light environments, parameters incorporating the proportion of the plant in leaves and rates of photosynthesis explained a greater amount of variation in RGR (e.g. LWR*Amass, R2=0.64) than did any single parameter related to whole-plant carbon gain. RGR generally declined with age and mass, which were used as scalars of ontogeny. LWR (and LAR) also declined for seven of the eight species-light treatments and A declined in four of the five species in high light. Decreasing LWR and A with ontogeny may have been partially responsible for decreasing RGR. Declines in RGR were not due to increased respiration resulting from an increase in the proportion of solely respiring tissue (roots and stems). In general, although LWR declined with ontogeny, specific rates of leaf, stem, and root respiration also decreased. The net result was that whole-plant respiration rates per unit leaf mass decreased for all eight treatments. Identifying the major determinants of variation in growth (e.g. LWR*Amass) across light environments, species and ontogeny contributes to the establishment of a framework for exploring limits to productivity and the nature of ecological success as measured by growth. The generality of these relationships both across the sources of variation we explored here and across other sources of variation in RGR needs further study.  相似文献   

2.
Abstract The relations between growth and internal nitrogen concentrations were investigated in nonnodulated Pisum sativum L. cv. Marma and Lemna gibba L. grown at relative rates of nitrate-N additions (RA) varying from 0.03 to 0.27 d 1(Pisum) and 0.05 to 0.40 d 1 (Lemna). At RA≤0.21 d 1(Pisum) and ≤0.30 d 1 (Lemna), the relative growth rate (RGR) correlated well with RA whereas higher RA was not met by any further increawse in growth rate. The tissue nitrogen concentrations at growth-limiting RA increased linearly with RGR. The slope of these lines indicate a maximum nitrogen productivity (amount of biomass formed per unit nitrogen and time) of 14.4 g DW g 1 Nd 1 for Pisum and 15.9 g DW g 1 N d 1 for Lemna. Extrapolation of the plots to RGR=0 yielded intercepts of 10–15 mg N g?1 DW for Pisum tissue, whereas for Lemna the intercepts were closer to the origin than for Pisum. These intercepts formally define a fraction of the total plant nitrogen that appears not to be active in production of new biomass, her termed ‘non-growth nitrogen’. The partitioning of nitrogen as well as biomass to the roots increased at low RA, and is discussed in relation to activity of shoots and roots, respectively.  相似文献   

3.
We investigated the extent to which leaf and root respiration (R) differ in their response to short‐ and long‐term changes in temperature in several contrasting plant species (herbs, grasses, shrubs and trees) that differ in inherent relative growth rate (RGR, increase in mass per unit starting mass and time). Two experiments were conducted using hydroponically grown plants. In the long‐term (LT) acclimation experiment, 16 species were grown at constant 18, 23 and 28 °C. In the short‐term (ST) acclimation experiment, 9 of those species were grown at 25/20 °C (day/night) and then shifted to a 15/10 °C for 7 days. Short‐term Q10 values (proportional change in R per 10 °C) and the degree of acclimation to longer‐term changes in temperature were compared. The effect of growth temperature on root and leaf soluble sugar and nitrogen concentrations was examined. Light‐saturated photosynthesis (Asat) was also measured in the LT acclimation experiment. Our results show that Q10 values and the degree of acclimation are highly variable amongst species and that roots exhibit lower Q10 values than leaves over the 15–25 °C measurement temperature range. Differences in RGR or concentrations of soluble sugars/nitrogen could not account for the inter‐specific differences in the Q10 or degree of acclimation. There were no systematic differences in the ability of roots and leaves to acclimate when plants developed under contrasting temperatures (LT acclimation). However, acclimation was greater in both leaves and roots that developed at the growth temperature (LT acclimation) than in pre‐existing leaves and roots shifted from one temperature to another (ST acclimation). The balance between leaf R and Asat was maintained in plants grown at different temperatures, regardless of their inherent relative growth rate. We conclude that there is tight coupling between the respiratory acclimation and the temperature under which leaves and roots developed and that acclimation plays an important role in determining the relationship between respiration and photosynthesis.  相似文献   

4.
The effects of insufficient and excessive mineral nutrition on the relative growth rate (RGR); the rate of total dark respiration (R); gross photosynthesis (Pg); and the contents of endogenous IAA, ABA, and cytokinins (CK) were studied in 20–60-day-old seedlings of plant species that differed in their responses to these factors: beet root (Amaranthus retroflexusL.), orchard-grass (Dactylis glomerataL.), and common wheat (Triticum aestivumL.). The changes in the level of mineral nutrition lowered the RGR and Pgvalues and the IAA/ABA and CK/ABA ratios and increased the Rand R/Pgvalues and ABA content, especially in A. retroflexusand T. aestivum. The authors propose a new way to assess the respiratory cost of adaptation to stress based on the relation between the RGR and the R/Pgvalues. The adaptation component of Ris shown to relate to the ABA content.  相似文献   

5.
The effect of the deficiency in mineral nutrients was investigated in plant species representing various adaptation groups (stress-tolerant, competitive, and ruderal plants). Dry and fresh weight, as well as the length of shoots and underground organs, were determined in 20- to 50-day-old seedlings. The ratio between the dry weights of shoot and root (SRR), relative growth rate (RGR), the rate of total dark respiration (R), gross photosynthesis (P g), and the proportion of the respiratory expenditures to gross photosynthesis (R/P g) were calculated. When affected by a deficiency in mineral nutrients, the weight of the whole plant decreased. In resistant species of clover (Trifolium pratense L.) and alfalfa (Medicago sativa L.), this reduction was insignificant, whereas, in the ruderal species amaranth (Amaranthus retroflexus L.), it was at its highest. In all the species investigated, the ratio R/P g was 38–46%. Under stress conditions, this index increased. Given a deficiency in mineral nutrients, the changes in SRR, RGR, and R/P g were greater in amaranth, suggesting that this plant species is less tolerant to stress. The correlation between RGR and R observed in amaranth under normal conditions indicates that the major energy expenditures are associated with growth. Under stress conditions, such a correlation was not observed. In more resistant species of clover and alfalfa, a weak positive correlation between RGR and R was observed both under normal and stress conditions. In these species, the deficiency in mineral nutrients probably brought about a reduction in the growth component of total dark respiration and a rise in the adaptation component. The complex of indices (R/P g, RGR, and SRR) and the extent of their variation in the seedlings describe the potential productivity and resistance of particular species to a deficiency in mineral nutrients and may characterize the adaptation type of the plants.  相似文献   

6.
  • Relative growth rate (RGR) plays an important role in plant adaptation to the light environment through the growth potential/survival trade‐off. RGR is a complex trait with physiological and biomass allocation components. It has been argued that herbivory may influence the evolution of plant strategies to cope with the light environment, but little is known about the relation between susceptibility to herbivores and growth‐related functional traits.
  • Here, we examined in 11 evergreen tree species from a temperate rainforest the association between growth‐related functional traits and (i) species’ shade‐tolerance, and (ii) herbivory rate in the field. We aimed at elucidating the differential linkage of shade and herbivory with RGR via growth‐related functional traits.
  • We found that RGR was associated negatively with shade‐tolerance and positively with herbivory rate. However, herbivory rate and shade‐tolerance were not significantly related. RGR was determined mainly by photosynthetic rate (Amax) and specific leaf area (SLA). Results suggest that shade tolerance and herbivore resistance do not covary with the same functional traits. Whereas shade‐tolerance was strongly related to Amax and to a lesser extent to leaf mass ratio (LMR) and dark respiration (Rd), herbivory rate was closely related to allocation traits (SLA and LMR) and slightly associated with protein content.
  • The effects of low light on RGR would be mediated by Amax, while the effects of herbivory on RGR would be mediated by SLA. Our findings suggest that shade and herbivores may differentially contribute to shape RGR of tree species through their effects on different resource‐uptake functional traits.
  相似文献   

7.
Partitioning of Respiration in an Intensively Managed Grassland   总被引:1,自引:0,他引:1  
Total (RTOT) and heterotrophic (RH) respiration were measured in an intensively managed perennial ryegrass (Lolium perenne L.) grassland. The overall aim of the study was to partition RTOT into RH and autotrophic respiration (RA). This was achieved as follows: (1) analyse the effect of air temperature, soil moisture content and leaf area index on RTOT and the influence of soil temperature and soil moisture content on RH; (2) combine these effects into separate empirical models for RTOT and RH and; (3) use these models to determine temporal trends in RTOT and RH and to assess the relative contribution of RH and RA to RTOT. CO2 fluxes were measured using a vented and thermostatically controlled perspex chamber in conjunction with a portable infrared gas analyser. RTOT was measured in plots with grass and RH in plots with bare soil. RTOT was related to air temperature and RH to soil temperature using exponential relationships. Both RTOT and RH were related to soil moisture content using lognormal relationships. RTOT was related to leaf area index using a linear relationship. These relationships were combined to produce statistical response functions that explained 87% and 84% of the variation in RTOT and RH, respectively. These relationships were combined with meteorological and leaf area index data to reconstruct daily and seasonal fluxes. RTOT values in wintertime were ~4 g C m−2 day−1 increasing to ~10 g C m−2 day−1 in summertime when temperatures and leaf area index were higher and soils were drier. RH has a similar seasonal trend to RTOT but was consistently lower. Wintertime values were ~2 g C m−2 day−1 and increased to ~5 g C m−2 day−1 in summertime. Before day of year 143, and after day of year 259 RH and RA represented 62% and 38% of RTOT, respectively. In the period between these days RH and RA both accounted for 50% of RTOT. In total during 2004 RTOT, RH and RA were 2.34, 1.31 and 1.03 kg C m−2, respectively.  相似文献   

8.
Increases in the concentration of atmospheric carbon dioxide may have a fertilizing effect on plant growth by increasing photosynthetic rates and therefore may offset potential growth decreases caused by the stress associated with higher temperatures and lower precipitation. However, plant growth is determined both by rates of net photosynthesis and by proportional allocation of fixed carbon to autotrophic tissue and heterotrophic tissue. Although CO2 fertilization may enhance growth by increasing leaf-level assimilation rates, reallocation of biomass from leaves to stems and roots in response to higher concentrations of CO2 and higher temperatures may reduce whole-plant assimilation and offset photosynthetic gains. We measured growth parameters, photosynthesis, respiration, and biomass allocation of Pinus ponderosa seedlings grown for 2 months in 2×2 factorial treatments of 350 or 650 bar CO2 and 10/25° C or 15/30° C night/day temperatures. After 1 month in treatment conditions, total seedling biomass was higher in elevated CO2, and temperature significantly enhanced the positive CO2 effect. However, after 2 months the effect of CO2 on total biomass decreased and relative growth rates did not differ among CO2 and temperature treatments over the 2-month growth period even though photosynthetic rates increased 7% in high CO2 treatments and decreased 10% in high temperature treatments. Additionally, CO2 enhancement decreased root respiration and high temperatures increased shoot respiration. Based on CO2 exchange rates, CO2 fertilization should have increased relative growth rates (RGR) and high temperatures should have decreased RGR. Higher photosynthetic rates caused by CO2 fertilization appear to have been mitigated during the second month of exposure to treatment conditions by a 3% decrease in allocation of biomass to leaves and a 9% increase in root:shoot ratio. It was not clear why diminished photosynthetic rates and increased respiration rates at high temperatures did not result in lower RGR. Significant diametrical and potentially compensatory responses of CO2 exchange and biomass allocation and the lack of differences in RGR of ponderosa pine after 2 months of exposure of high CO2 indicate that the effects of CO2 fertilization and temperature on whole-plant growth are determined by complex shifts in biomass allocation and gas exchange that may, for some species, maintain constant growth rates as climate and atmospheric CO2 concentrations change. These complex responses must be considered together to predict plant growth reactions to global atmospheric change, and the potential of forest ecosystems to sequester larger amounts of carbon in the future.  相似文献   

9.
We warmed the top soil of a mature coniferous forest stand by means of heating cables on control and trenched plots within 24 h by 10°C at 1 cm soil depth (9°C at 5 cm depth) and measured the effect on the autotrophic (RA) and heterotrophic (RH) component of total soil CO2 efflux (RS). The short time frame of warming enabled us to exclude confounding fluctuations in soil moisture and carbon (C) flow from the canopy. The results of the field study were backed up by a lab soil incubation experiment. During the first 12 h of warming, RA strongly responded to soil warming; The Q 10 values were 5.61 and 6.29 for 1 and 5 cm soil depth temperature. The Q 10 values for RA were almost twice as high as the Q 10 values of RH (3.04 and 3.53). Q 10 values above 5 are above reasonable plant physiological values for root respiration. We see interactions of roots, mycorrhizae and heterotrophic microbes, combined with fast substrate supply to the rhizosphere as an explanation for the high short-term temperature response of RA. When calculated over the whole duration (24 h) of the field soil-warming experiment, temperature sensitivities of RA and RH were similar (no significant difference at P < 0.05); Q 10 values were 3.16 and 3.96 for RA and 2.94 and 3.35 for RH calculated with soil temperatures at 1 and 5 cm soil depth, respectively. Laboratory incubation showed that different soil moisture contents of trenched and control plots affected rates of RH, but did not affect the temperature sensitivity of RH. We conclude that a single parameter is sufficient to describe the temperature sensitivity of RS in soil C models which operate on larger temporal and spatial scales. The strong short-term response of RA may be of relevance in soils suspected to experience increasingly strong diurnal temperature variations.  相似文献   

10.
Factors constraining the geographic ranges of broadleaf tree species in eastern North America were examined in common gardens along a ~1500 km latitudinal transect travers in grange boundaries of four target species: trembling aspen (Populus tremuloides) and paper birch (Betula papyrifera) to the north vs. eastern cottonwood (Populus deltoides) and sweet gum (Liquidambar styraciflua) to the south. In 2006 and 2007, carbon‐use efficiency (CUE), the proportion of assimilated carbon retained in biomass, was estimated for seedlings of the four species as the quotient of relative growth rate (RGR) and photosynthesis per unit tree mass (Atree). In aspen and birch, CUE and RGR declined significantly with increasing growth temperature, which spanned 9 °C across gardens and years. The 37% (relative) CUE decrease from coolest to warmest garden correlated with increases in leaf nighttime respiration (Rleaf) and the ratio of Rleaf to leaf photosynthesis (R%A). For cottonwood and sweet gum, however, similar increases in Rleaf and R%A accompanied modest CUE declines, implying that processes other than Rleaf were responsible for species differences in CUE's temperature response. Our findings illustrate marked taxonomic variation, at least among young trees, in the thermal sensitivity of CUE, and point to potentially negative consequences of climate warming for the carbon balance, competitive ability, and persistence of two foundation species in northern temperate and boreal forests.  相似文献   

11.
Some plants have the ability to maintain similar respiratory rates (measured at the growth temperature), even when grown at different temperatures, a phenomenon referred to as respiratory homeostasis. The underlying mechanisms and ecological importance of this respiratory homeostasis are not understood. In order to understand this, root respiration and plant growth were investigated in two wheat cultivars (Triticum aestivum L. cv. Stiletto and cv. Patterson) with a high degree of homeostasis, and in one wheat cultivar (T. aestivum L. cv. Brookton) and one rice cultivar (Oryza sativa L. cv. Amaroo) with a low degree of homeostasis. The degree of homeostasis (H) is defined as a quantitative value, which occurs between 0 (no acclimation) and 1 (full acclimation). These plants were grown hydroponically at constant 15 or 25 °C. A good correlation was observed between the rate of root respiration and the relative growth rates (RGR) of whole plant, shoot or root. The plants with high H showed a tendency to maintain their RGR, irrespective of growth temperature, whereas the plants with low H grown at 15 °C showed lower RGR than those grown at 25 °C. Among several parameters of growth analysis, variation in net assimilation rate per shoot mass (NARm) appeared to be responsible for the variation in RGR and rates of root respiration in the four cultivars. The plants with high H maintained their NARm at low growth temperature, but the plants with low H grown at 15 °C showed lower NARm than those grown at 25 °C. It is concluded that respiratory homeostasis in roots would help to maintain growth rate at low temperature due to a smaller decrease in net carbon gain at low temperature. Alternatively, growth rate per se may control the demand of respiratory ATP, root respiration rates and sink demands of photosynthesis. The contribution of nitrogen uptake to total respiratory costs was also estimated, and the effects of a nitrogen leak out of the roots and the efficiency of respiration on those costs are discussed.  相似文献   

12.
树干呼吸(E_s)是森林生态系统碳循环过程的重要组成部分,深入理解树干呼吸过程对未来气候变暖的响应及反馈机制有助于更加精确地估算森林生态系统碳储量。为揭示毛白杨树干呼吸及其温度敏感性的昼夜变化和季节动态规律,利用Li-Cor6400便携式光合作用测定系统及其配套使用的土壤呼吸测量气室(LI-6400-09)对冀南平原区毛白杨的树干呼吸和树干温度实施为期1年的连续监测。结果表明:(1)在生长季,毛白杨树干呼吸与树干温度之间在晚上呈现正相关的关系(R~2=0.88);相反,两者在白天为负相关的关系(R~2=0.96)。(2)整个观测期内,毛白杨树干呼吸和树干温度均呈现"钟形"的变化曲线,树干呼吸与树干温度之间存在着较好的指数函数关系(R~2=0.93),且树干呼吸的温度敏感性系数(Q_(10))为2.62;不同季节毛白杨树干呼吸的Q_(10)存在差异,生长季的Q_(10)(1.95)明显低于非生长季(3.00),表明生长呼吸和维持呼吸对温度的响应也并不相同。(3)温度矫正后的毛白杨树干呼吸(R_(15))在昼夜和季节尺度上均存在明显的变异,即夜晚的R_(15)显著高于白天(P0.01),生长季的R_(15)明显高于非生长季(P0.05);树干可溶性糖含量与生长季的R_(15)存在较好的相关性(R~2=0.52),而非生长季的R_(15)却主要受到树干淀粉含量的影响。研究结果表明,在生长季,毛白杨树干呼吸的在日变化主要受到温度的影响,而在季节尺度上Q_(10)的变异则与树干呼吸中维持呼吸所占比例及树干中非结构性碳水化合物(可溶性糖和淀粉)的含量及类型紧密相关。  相似文献   

13.
Abstract Net nitrate uptake rates were measured and the kinetics calculated in non-nodulated Pisum sativum L. cv. Marma and Lemna gibba L. adapted to constant relative rates of nitrate-N additions (RA), ranging from 0.03 to 0.27 d?1 for Pisum and from 0.05 to 0.40 d?1 for Lemna, Vmax of net nitrate uptake (measured in the range 10 to 100 mmol m?3 nitrate, i.e. ‘system I’) increased with RA in the growth limiting range but decreased when RA exceeded the relative growth rate (RGR), Km was not significantly related to changes in RA. On the basis of previous 13N-flux experiments, it is concluded that the differences in Vmax at growth limiting RA are attributable to differences in influx rates. Linear relationships between Vmax and tissue nitrogen concentrations were obtained in the growth limiting range for both species, and extrapolated intercepts relate well with the previously defined minimal nitrogen concentrations for plant growth (Oscarson, Ingemarsson & Larsson, 1989). Analysis of Vmax for net nitrate uptake on intact plant basis in relation to nitrogen demand during stable, nitrogen limited, growth shows an increased overcapacity at lower RA values in both species, which is largely explained by the increased relative root size at low RA. A balancing nitrate concentration, defined as the steady state concentration needed to sustain the relative rate of increase in plant nitrogen (RN), predicted by RA, was calculated for both species. In the growth limiting range, this value ranges from 3.5 mmol m?3 (RA 0.03 d?1) to 44 mmol m?3 (RA 0.21 d?1) for Pisum and from 0.2 mmol m?3 (RA 0.05 d?1) to 5.4 mmol m?3 (RA 0.03 d?1) for Lemna. It is suggested that this value can be used as a unifying measure of the affinity for nitrate, integrating the performance of the nitrate uptake system with nitrate flux and long term growth and demand for nitrogen.  相似文献   

14.
A whole-plant carbon balance model incorporating a light acclimation response was developed for Alocasia macrorrhiza based on empirical data and the current understanding of light acclimation in this species. The model was used to predict the relative growth rate (RGR) for plants that acclimated to photon flux density (PFD) by changing their leaf type, and for plants that produced only sun or shade leaves regardless of PFD. The predicted RGR was substantially higher for plants with shade leaves than for those with sun leaves at low PFD. However, the predicted RGR was not higher, and in fact was slightly lower, for plants with sun leaves than for those with shade leaves at high PFD. The decreased leaf area ratios (LARs) of the plants with sun leaves counteracted their higher photosynthetic capacities per unit leaf area (Amax). The model was manipulated by changing parameters to examine the sensitivity of RGR to variation in single factors. Overall, RGR was most sensitive to LAR and showed relatively little sensitivity to variation in Amax or maintenance respiration. Similarly, RGR was relatively insensitive to increases in leaf life-span beyond those observed. Respiration affected RGR only at low PFD, whereas Amax was moderately important only at high PFD.  相似文献   

15.
Plants of alfalfa (Medicago sativa) and orchard grass (Dactylus glomerata) were grown in controlled environment chambers at two CO2 concentrations (350 and 700 μmol mol-1) and 4 constant day/night growth temperatures of 15, 20, 25 and 30°C for 50–90 days to determine changes in growth and whole plant CO2 efflux (dark respiration). To facilitate comparisons with other studies, respiration data were expressed on the basis of leaf area, dry weight and protein. Growth at elevated CO2 increased total plant biomass at all temperatures relative to ambient CO2, but the relative enhancement declined (P≤0.05) as temperature increased. Whole plant respiration (Rd) at elevated CO2 declined at 15 and 20°C in D. glomerata on an area, weight or protein basis and in M. sativa on a weight or protein basis when compared to ambient CO2. Separation of Rd into respiration required for growth (Rg) and maintenance (Rm) showed a significant effect of elevated CO2 on both components. Rm was reduced in both species but only at lower temperatures (15°C in M. sativa and 15 and 20°C in D. glomerata). The effect on Rm could not be accounted for by protein content in either species. Rg was also reduced with elevated CO2; however no particular effect of temperature was observed, i. e. Rg was reduced at 20, 25 and 30°C in M. sativa and at 15 and 25°C in D. glomerata. For the two perennial species used in the present study, the data suggest that both Rg and Rm can be reduced by anticipated increases in atmospheric CO2; however, CO2 inhibition of total plant respiration may decline as a function of increasing temperature  相似文献   

16.
量化森林土壤呼吸(RS)及其组分对准确地评估森林土壤碳吸存极其重要。该文以鼎湖山南亚热带季风常绿阔叶林及其演替系列针阔叶混交林和马尾松(Pinus massoniana)林为研究对象, 采用挖壕沟法结合静态气室CO2测定法对这3种林分类型的RS进行分离量化。结果表明: 鼎湖山3种森林演替系列上的森林RS及其组分(自养呼吸RA、异养呼吸RH)均呈现出明显的季节动态, 表现为夏季最高、冬季最低的格局。在呼吸总量上, 季风常绿阔叶林显著高于针阔叶混交林和马尾松林, 但混交林与马尾松林之间差异不显著; RA除季风常绿阔叶林显著大于针阔叶混交林外, 其余林分之间差异不显著; 对于RH来说, 3个林分之间均无显著差异。随着森林正向演替的进行, 由马尾松林至针阔叶混交林至季风常绿阔叶林, RA对土壤总呼吸的年平均贡献率分别为(39.48 ± 15.49)%、(33.29 ± 17.19)%和(44.52 ± 10.67)%, 3个林分之间差异不显著。方差分析结果表明, 土壤温度是影响RS及其组分的主要环境因子, 温度与RS及其组分呈显著的指数关系; 土壤含水量对RS的影响不显著, 甚至表现为轻微的抑制现象, 但未达到显著性水平。对温度敏感性指标Q10值的分析表明, 3个林分均为RA的温度敏感性最大, RH的温度敏感性最小。  相似文献   

17.
Leaf respiration and photosynthesis will respond differently to an increase in temperature during night, which can be more relevant in sensitive ecosystems such as Antarctica. We postulate that the plant species able to colonize the Antarctic Peninsula – Colobanthus quitensis (Kunth) Bartl. and Deschampsia antarctica Desv. – are able to acclimate their foliar respiration and to maintain photosynthesis under nocturnal warming to sustain a positive foliar carbon balance. We conducted a laboratory experiment to evaluate the effect of time of day (day and night) and nocturnal warming on dark respiration. Short (E0 and Q10) and long‐term acclimation of respiration, leaf carbohydrates, photosynthesis (Asat) and foliar carbon balance (R/A) were evaluated. The results suggest that the two species have differential thermal acclimation respiration, where D. antarctica showed more thermosensitivity to short‐term changes in temperature than C. quitensis. Experimental nocturnal warming affected respiration at daytime differentially between the two species, with a significant increase of R10 and Asat in D. antarctica, while no changes on respiration were observed in C. quitensis. Long thermal treatments of the plants indicated that nocturnal but not diurnal respiration could acclimate in both species, and to a greater extent in C. quitensis. Non‐structural carbohydrates were related with respiration in C. quitensis but not in D. antarctica, suggesting that respiration in the former species is likely controlled by total soluble sugars and starch during day and night, respectively. Finally, foliar carbon balance was differentially improved under warming conditions in Antarctic plants by different mechanisms, with C. quitensis deploying respiratory acclimation, while D. antarctica increased its Asat.  相似文献   

18.
全球陆地生态系统光合作用与呼吸作用的温度敏感性   总被引:3,自引:0,他引:3  
游桂莹  张志渊  张仁铎 《生态学报》2018,38(23):8392-8399
基于全球647套通量数据,定量分析了全球尺度下生态系统光合作用和呼吸作用的温度敏感性(Q10)随纬度、气候和植被的分布规律。结果表明:在全球尺度下,光合作用和呼吸过程的温度敏感性(Q10,G和Q10,R)都随纬度的升高而增加,其中Q10,G和Q10,R的均值分别为3.99±0.21和2.28±0.074。除热带多树草原、常绿落叶林外,Q10,G均大于Q10,R值。不同植被类型的温度敏感性存在显著性差异,表现为:针叶林阔叶林;落叶林常绿林,其中生态系统的季节性变异是造成差异的主要原因。当植被类型和纬度区域共同影响Q10值时,植被类型对Q10值的总变异贡献更大。气候类型对Q10,G和Q10,R都有显著影响。在气候带上,干旱带的Q10,G最小,而冷温带的Q10,G最高。不同气候类型下(除温带草原气候外)的Q10,G都大于Q10,R。在极端条件下,温度可能不在是主导因素,而水分对温度敏感性的影响不可忽略,今后的研究需要更多的关注生态系统温度敏感性对水分变化的响应。  相似文献   

19.
den Hertog  J.  Stulen  I.  Lambers  H. 《Plant Ecology》1993,104(1):369-378
The response ofPlantago major ssp,pleiosperma plants, grown on nutrient solution in a climate chamber, to a doubling of the ambient atmospheric CO2 concentration was investigated. Total dry matter production was increased by 30% after 3 weeks of exposure, due to a transient stimulation of the relative growth rate (RGR) during the first 10 days. Thereafter RGR returned to the level of control plants. Photosynthesis, expressed per unit leaf area, was stimulated during the first two weeks of the experiment, thereafter it dropped and nearly reached the level of the control plants. Root respiration was not affected by increased atmospheric CO2 levels, whereas shoot, dark respiration was stimulated throughout the experimental period. Dry matter allocation over leaves stems and roots was not affected by the CO2 level. SLA was reduced by 10%, which can partly be explained by an increased dry matter content of the leaves. Both in the early and later stages of the experiment, shoot respiration accounted for a larger part of the carbon budget in plants grown at elevated atmospheric CO2. Shifts in the total carbon budget were mainly due to the effects on shoot respiration. Leaf growth accounted for nearly 50% of the C budget at all stages of the experiment and in both treatments.Abbreviations LAR leaf area ratio - LWR leaf weight ratio - RGR relative growth rate - R/S root to shoot ratio - RWR root weight ratio - SLA specific leaf area - SWR stem weight ratio  相似文献   

20.

Aims and Background

While the temperature response of soil respiration (RS) has been well studied, the partitioning of heterotrophic respiration (RH) by soil microbes from autotrophic respiration (RA) by roots, known to have distinct temperature sensitivities, has been problematic. Further complexity stems from the presence of roots affecting RH, the rhizosphere priming effect. In this study the short-term temperature responses of RA and RH in relation to rhizosphere priming are investigated.

Methods

Temperature responses of RA, RH and rhizosphere priming were assessed in microcosms of Poa cita using a natural abundance δ13C discrimination approach.

Results

The temperature response of RS was found to be regulated primarily by RA, which accounted for 70 % of total soil respiration. Heterotrophic respiration was less sensitive to temperature in the presence of plant roots, resulting in negative priming effects with increasing temperature.

Conclusions

The results emphasize the importance of roots in regulating the temperature response of RS, and a framework is presented for further investigation into temperature effects on heterotrophic respiration and rhizosphere priming, which could be applied to other soil and vegetation types to improve models of soil carbon turnover.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号