Long-term Effects Of Elevated CO Research Articles

Long-term Effects of Elevated CO on the Proliferation of Cyanophage PP

Much of the research effort focused on the impacts of elevated CO2 on marine algae but very little work was done on freshwater algae, or on freshwater algal viruses. In this paper, we studied the impacts of elevated CO2 on the infection of a freshwater cyanobacterium (wild Leptolyngbya sp.) by cyanophage PP that have a wide distribution in China. In a 12-month experiment, logarithmic-phase host cells were infected with cyanophage PP at 370 or 740 µatm pCO2 concentrations; the burst size, lysing cycle and proportion of adsorption were measured. The results showed that the proportion of adsorption, and burst sizes of cyanophage PP increased significantly with elevated CO2 concentrations, and the proportion of adsorption increased gradually within the 12 months with the gradual increment of cell width. The result indicated that elevated CO2 concentration may have significantinfluences on the proliferation dynamics of cyanophage–host systems, and some of the influences may increase gradually in a long-term.

Effects of Long-term Elevated CO 2 Fumigation on Microbial Communities in a Wetland Soil

In this study, we studied the effects of different Carbon dioxide concentrations on microbial community diversity in a wetland ecosystem in northern China. The open-top chamber (OTC) was situated in the boggy soil in which the dominant plant is Deyeuxia angustifolia. Between 2010 and 2013, we maintained the average Carbon dioxide concentration in OTC at 370 ppm, 550 ppm and 700 ppm. Soil samples were collected during the last year. Results show that soil fungal diversity indices in the 0–10 cm soil layer were significantly decreased by elevated concentration of CO2 by 4.570 in ck. It was increased by 4.456, 4.373 and 4.13 by 350 ppm, 500 ppm and 700 ppm CO2, respectively. Soil bacterial diversity indices in the 0–10 cm soil layer, however, were not significantly influenced by elevated CO2 (P > 0.05). The results of principal component analysis (PCA) and Redundancy analysis (RDA) indicate that elevated CO2 had no strict specificity with bacterial community diversity but strict specificity with fungal community, while environmental condition had great influence on fungal community diversity and soil nutrient. Organic carbon, nitrate nitrogen (NO-N), C/N, total nitrogen (N) and pH were the primary impact factors. These results suggest that the environmental conditions exhibit great influence on the community diversity of fungi and bacteria. It is also found that soil nutrient were indicative of the change of community diversity of fungi and bacteria.

Differential gene expression in senescing leaves of two silver birch genotypes in response to elevated CO2 and tropospheric ozone

Long-term effects of elevated CO(2) and O(3) concentrations on gene expression in silver birch (Betula pendula Roth) leaves were studied during the end of the growing season. Two birch genotypes, clones 4 and 80, with different ozone growth responses, were exposed to 2x ambient CO(2) and/or O(3) in open-top chambers (OTCs). Microarray analyses were performed after 2 years of exposure, and the transcriptional profiles were compared to key physiological characteristics during leaf senescence. There were genotypic differences in the responses to CO(2) and O(3). Clone 80 exhibited greater transcriptional response and capacity to alter metabolism, resulting in better stress tolerance. The gene expression patterns of birch leaves indicated contrasting responses of senescence-related genes to elevated CO(2) and O(3). Elevated CO(2) delayed leaf senescence and reduced associated transcriptional changes, whereas elevated O(3) advanced leaf senescence because of increased oxidative stress. The combined treatment demonstrated that elevated CO(2) only temporarily alleviated the negative effects of O(3). Gene expression data alone were insufficient to explain the O(3) response in birch, and additional physiological and biochemical data were required to understand the true O(3) sensitivity of these clones.

Short and long-term effects of elevated CO 2 on Lolium perenne rhizodeposition and its consequences on soil organic matter turnover and plant N yield

It is still unclear whether elevated CO 2 increases plant root exudation and consequently affects the soil microbial biomass. The effects of elevated CO 2 on the fate of the C and nitrogen (N) contained in old soil organic matter pools is also unclear. In this study the short and long-term effects of elevated CO 2 on C and N pools and fluxes were assessed by growing isolated plants of ryegrass ( Lolium perenne) in glasshouses at elevated and ambient atmospheric CO 2 and using soil from the New Zealand FACE site that had >4 years exposure to CO 2 enrichment. Using 14CO 2 pulse labelling, the effects of elevated CO 2 on C allocation within the plant-soil system were studied. Under elevated CO 2 more root derived C was found in the soil and in the microbial biomass 48 h after labelling. The increased availability of substrate significantly stimulated soil microbial growth and acted as priming effect, enhancing native soil organic matter decomposition regardless of the mineral N supply. Despite indications of faster N cycling in soil under elevated CO 2, N availability to plants stayed unchanged. Soil previously exposed to elevated CO 2 exhibited a higher N cycling rate but again there was no effect on plant N uptake. With respect to the difficulties of extrapolating glasshouse experiment results to the field, we concluded that the accumulation of coarse organic matter observed in the field under elevated CO 2 was probably not created by an imbalance between C and N but was likely to be due to more complex phenomena involving soil mesofauna and/or other nutrients limitations.

Photosynthetic acclimation to elevated atmospheric CO(2) concentration in the Florida scrub-oak species Quercus geminata and Quercus myrtifolia growing in their native environment.

Long-term effects of elevated CO(2) concentration (ambient plus 350 &mgr;mol mol(-1)) on leaf photosynthetic acclimation of two species of a scrub-oak community, Quercus myrtifolia Willd. and Quercus geminata Small, were studied. Plants of both species were grown in open-top chambers in their natural habitat at Kennedy Space Center, Florida, USA. Compared to ambient CO(2), elevated CO(2) stimulated photosynthetic rates by 73 and 51% for Q. geminata and Q. myrtifolia, respectively. Maximum rate of carboxylation (V(cmax)) was significantly reduced by elevated CO(2) in Q. myrtifolia (28%) but not in Q. geminata. Maximum rate of potential electron transport (J(max)) was not significantly reduced by elevated CO(2) in either species. In response to elevated CO(2), specific leaf area decreased in Q. myrtifolia (22%), but not in Q. geminata. Elevated CO(2) caused a significant accumulation of sugars (54%) and starch (264%) in Q. myrtifolia leaves, but not in Q. geminata leaves. Total Rubisco activity in Q. myrtifolia leaves was reduced 40% by elevated CO(2), whereas no significant reduction occurred in Q. geminata leaves. Although both species share a common habitat, they exhibited marked differences in photosynthetic acclimation to elevated CO(2) concentration.

Long-term effects of elevated CO2 and temperature on populations of the peach potato aphid Myzus persicae and its parasitoid Aphidius matricariae.

Model terrestrial ecosystems were set-up in the Ecotron controlled environment facility. The effects of elevated CO2 (ambient + 200 [Formula: see text]mol/mol) and temperature (ambient + 2.0°C) on plant chemistry, the abundance of the peach potato aphid Myzus persicae, and on the performance of one of its parasitoids Aphidius matricariae, were studied. Total above-ground plant biomass at the end of the experiment was not affected by elevated atmospheric CO2, nor were foliar nitrogen and carbon concentrations. Elevated temperature decreased final plant biomass while leaf nitrogen concentrations increased. Aphid abundance was enhanced by both the␣CO2 and temperature treatment. Parasitism rates remained unchanged in elevated CO2, but showed an increasing trend in conditions of elevated temperature. Our results suggest that M. persicae, an important pest of many crops, might increase its abundance under conditions of climate change.