Effects of Elevated CO2 and N Addition on Growth and N2 Fixation of a Legume Subshrub (Caragana microphylla Lam.) in Temperate Grassland in China

It is well demonstrated that the responses of plants to elevated atmospheric CO2 concentration are species-specific and dependent on environmental conditions. We investigated the responses of a subshrub legume species, Caragana microphylla Lam., to elevated CO2 and nitrogen (N) addition using open-top chambers in a semiarid temperate grassland in northern China for three years. Measured variables include leaf photosynthetic rate, shoot biomass, root biomass, symbiotic nitrogenase activity, and leaf N content. Symbiotic nitrogenase activity was determined by the C2H2 reduction method. Elevated CO2 enhanced photosynthesis and shoot biomass by 83% and 25%, respectively, and the enhancement of shoot biomass was significant only at a high N concentration. In addition, the photosynthetic capacity of C. microphylla did not show down-regulation under elevated CO2. Elevated CO2 had no significant effect on root biomass, symbiotic nitrogenase activity and leaf N content. Under elevated CO2, N addition stimulated photosynthesis and shoot biomass. By contrast, N addition strongly inhibited symbiotic nitrogenase activity and slightly increased leaf N content of C. microphylla under both CO2 levels, and had no significant effect on root biomass. The effect of elevated CO2 and N addition on C. microphylla did not show interannual variation, except for the effect of N addition on leaf N content. These results indicate that shoot growth of C. microphylla is more sensitive to elevated CO2 than is root growth. The stimulation of shoot growth of C. microphylla under elevated CO2 or N addition is not associated with changes in N2-fixation. Additionally, elevated CO2 and N addition interacted to affect shoot growth of C. microphylla with a stimulatory effect occurring only under combination of these two factors

Diabetic and nondiabetic patients with left main and/or 3-vessel coronary artery disease: comparison of outcomes with cardiac surgery and paclitaxel-eluting stents.

OBJECTIVES: This study was designed to compare contemporary surgical revascularization (coronary artery bypass graft surgery [CABG]) versus TAXUS Express (Boston Scientific, Natick, Massachusetts) paclitaxel-eluting stents (PES) in diabetic and nondiabetic patients with left main and/or 3-vessel disease. BACKGROUND: Although the prevalence of diabetes mellitus is increasing, the optimal coronary revascularization strategy in diabetic patients with complex multivessel disease remains controversial. METHODS: The SYNTAX (SYNergy between percutaneous coronary intervention with TAXus and cardiac surgery) study randomly assigned 1,800 patients (452 with medically treated diabetes) to receive PES or CABG. RESULTS: The overall 1-year major adverse cardiac and cerebrovascular event rate was higher among diabetic patients treated with PES compared with CABG, but the revascularization method did not impact the death/stroke/myocardial infarction rate for nondiabetic patients (6.8% CABG vs. 6.8% PES, p = 0.97) or for diabetic patients (10.3% CABG vs. 10.1% PES, p = 0.96). The presence of diabetes was associated with significantly increased mortality after either revascularization treatment. The incidence of stroke was higher among nondiabetic patients after CABG (2.2% vs. PES 0.5%, p = 0.006). Compared with CABG, mortality was higher after PES use for diabetic patients with highly complex lesions (4.1% vs. 13.5%, p = 0.04). Revascularization with PES resulted in higher repeat revascularization for nondiabetic patients (5.7% vs. 11.1%, p < 0.001) and diabetic patients (6.4% vs. 20.3%, p < 0.001). CONCLUSIONS: Subgroup analyses suggest that the 1-year major adverse cardiac and cerebrovascular event rate is higher among diabetic patients with left main and/or 3-vessel disease treated with PES compared with CABG, driven by an increase in repeat revascularization. However, the composite safety end point (death/stroke/myocardial infarction) is comparable between the 2 treatment options for diabetic and nondiabetic patients. Although further study is needed, these exploratory results may extend the evidence for PES use in selected patients with less complex left main and/or 3-vessel lesions. (SYNergy Between PCI With TAXus and Cardiac Surgery [SYNTAX]; NCT00114972)

Bypass versus drug-eluting stents at three years in SYNTAX patients with diabetes mellitus or metabolic syndrome.

BACKGROUND: Diabetes mellitus increases adverse outcomes after coronary revascularization; however, the impact of metabolic syndrome is unclear. We examined the impact of diabetes and metabolic syndrome on coronary artery bypass graft surgery (CABG) and stenting outcomes to determine the optimal revascularization option for the treatment of complex coronary artery disease. METHODS: Patients (n = 1,800) with left main or three-vessel disease or both were randomly allocated to treatment with a TAXUS Express(2) paclitaxel-eluting stent (PES) or CABG, and were included in predefined nondiabetic (n = 1,348) or diabetic subgroups (n = 452); 258 patients with diabetes also had metabolic syndrome. RESULTS: Among diabetic patients, the 3-year major adverse cardiac and cerebrovascular event (MACCE) rate (22.9% CABG, 37.0% PES; p = 0.002) and revascularization rate (12.9% CABG, 28.0% PES; p < 0.001) were higher after PES treatment. Diabetes increased MACCE rates among PES-treated patients, but had little impact on results after CABG. Compared with CABG, PES treatment yielded comparable MACCE in diabetic patients (30.5% versus 29.8%, p =0.98) and nondiabetic patients (20.2% versus 20.3%, p =0.99) with low Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiac Surgery (SYNTAX) study scores of 22 or less. For patients with SYNTAX Scores of 33 or greater, MACCE rates were lower with CABG (18.5% versus 45.9%, p < 0.001 diabetic; 19.8% versus 30.0%, p = 0.01 nondiabetic). Metabolic syndrome did not significantly predict MACCE or repeat revascularization. CONCLUSIONS: These exploratory analyses suggest that among diabetic patients with complex left main or three-vessel disease, or both, 3-year MACCE is higher after PES compared with CABG. Although PES is a potential treatment option in patients with less complex lesions, CABG should be the revascularization option of choice for patients with more complex anatomic disease, especially with concurrent diabetes. Metabolic syndrome had little impact on 3-year outcomes

Assessing nature’s contributions to people: Recognizing culture, and diverse sources of knowledge, can improve assessments

A major challenge today and into the future is to maintain or enhance beneficial contributions of nature to a good quality of life for all people. This is among the key motivations of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), a joint global effort by governments, academia, and civil society to assess and promote knowledge of Earth's biodiversity and ecosystems and their contribution to human societies in order to inform policy formulation. One of the more recent key elements of the IPBES conceptual framework (1) is the notion of nature's contributions to people (NCP), which builds on the ecosystem service concept popularized by the Millennium Ecosystem Assessment (MA) (2). But as we detail below, NCP as defined and put into practice in IPBES differs from earlier work in several important ways. First, the NCP approach recognizes the central and pervasive role that culture plays in defining all links between people and nature. Second, use of NCP elevates, emphasizes, and operationalizes the role of indigenous and local knowledge in understanding nature's contribution to people

Loss of plant biodiversity eliminates stimulatory effect of elevated CO2 on earthworm activity in grasslands

Earthworms are among the world's most important ecosystem engineers because of their effects on soil fertility and plant productivity. Their dependence on plants for carbon, however, means that any changes in plant community structure or function caused by rising atmospheric CO2 or loss of plant species diversity could affect earthworm activity, which may feed back on plant communities. Production of surface casts measured during three consecutive years in field experimental plots (n = 24, 1.2 m(2)) planted with local calcareous grassland species that varied in plant species richness (diversity levels: high, 31 species; medium, 12; low, 5) and were exposed to ambient (356 μl CO2 l(-1)) or elevated (600 μl CO2 l(-1)) CO2 was only consistently stimulated in high diversity plots exposed to elevated CO2 (+120 %, 31 spp: 603 ± 52 under ambient CO2 vs. 1,325 ± 204 g cast dwt. m(-2) year(-1) under elevated CO2 in 1996; +77 %, 940 ± 44 vs. 1,663 ± 204 g cast dwt. m(-2) year(-1) in 1998). Reductions in plant diversity had little effect on cast production in ecosystems maintained at ambient CO2, but the stimulatory effect of elevated CO2 on cast production disappeared when plant species diversity was decreased to 12 and 5 species. High diversity plots were also the only communities that included plant species that an earlier field study showed to be among the most responsive to elevated CO2 and to be most preferred by earthworms to deposit casts near. Further, the +87 % CO2-induced increase in cast production measured over the 3 years corresponded to a parallel increase in cumulative total nitrogen of 5.7 g N m(-2) and would help explain the large stimulation of aboveground plant biomass production observed in high-diversity communities under elevated CO2. The results of this study demonstrate how the loss of plant species from communities can alter responses of major soil heterotrophs and consequently ecosystem biogeochemistry

Plant diversity enhances ecosystem responses to elevated CO2 and nitrogen deposition

http://www.nature.com/natureHuman actions are causing declines in plant biodiversity, increases in atmospheric CO2 concentrations and increases in nitrogen deposition; however, the interactive effects of these factors on ecosystem processes are unknown1, 2. Reduced biodiversity has raised numerous concerns, including the possibility that ecosystem functioning may be affected negatively1, 2, 3, 4, which might be particularly important in the face of other global changes5, 6. Here we present results of a grassland field experiment in Minnesota, USA, that tests the hypothesis that plant diversity and composition influence the enhancement of biomass and carbon acquisition in ecosystems subjected to elevated atmospheric CO2 concentrations and nitrogen deposition. The study experimentally controlled plant diversity (1, 4, 9 or 16 species), soil nitrogen (unamended versus deposition of 4 g of nitrogen per m2 per yr) and atmospheric CO2 concentrations using free-air CO2 enrichment (ambient, 368 micromol mol-1, versus elevated, 560 micromol mol-1). We found that the enhanced biomass accumulation in response to elevated levels of CO2 or nitrogen, or their combination, is less in species-poor than in species-rich assemblages