Contributions of C 3 and C 4 plants to higher trophic levels in an Amazonian savanna

Abstract We studied the energy¯ow from C 3 and C 4 plants to higher trophic levels in a central Amazonian savanna by comparing the carbon stable-isotope ratios of potential food plants to the isotope ratios of species of dierent consumer groups. All C 4 plants encountered in our study area were grasses and all C 3 plants were bushes, shrubs or vines. Dierences in d 13 C ratios among bushes (" x = A30.8, SD = 1.2), vines (" x = A30.7, SD = 0.46) and trees (" x = A29.7, SD = 1.5) were small. However the mean d 13 C ratio of dicotyledonous plants (" x = A30.4, SD = 1.3) was much more negative than that of the most common grasses (" x = A13.4, SD = 0.27). The insect primary consumers had d 13 C ratios which ranged from a mean of A29.5 (SD = 0.47) for the grasshopper Tropidacris collaris to a mean of A14.7 (SD = 0.56) for a termite (Nasutitermes sp.), a range similar to that of the vegetation

RAPELD: a modification of the Gentry method for biodiversity surveys in long-term ecological research sites

Our objectives were to develop a method that would be appropriate for long-term ecological studies, but that would permit rapid surveys to evaluate biotic complementarity and land-use planning in Amazonia. The Amazon basin covers about 7 million km². Therefore, even a sparse coverage, with one sample site per 10.000 km², would require about 700 sampling sites. Financial considerations limit the number of sites and investment at each site, but incomplete coverage makes evaluation of biotic complementarity difficult or impossible (Reddy & Dávalos 2003). Our next challenge is to install similar systems throughout Amazonia. The cost, based on modification of Al Gentry's original design is moderate (less than US$ 50.000 per site if it is not necessary to immediately identify all vascular plants in plots) and we can obtain RAP results for most taxa in the short term at much lower cost. However, biological surveys will only be relevant if the local people participate and the surveys serve as much to teach the local communities about the value of their natural resources as they serve to teach the international community about biodiversity. Therefore, we want to see each site run as a long-term ecological research project by local people and institutions. Biological surveys are an important tool in land-use planning, but only the local people can implement those plans

Diverse anthropogenic disturbances shift Amazon forests along a structural spectrum

Amazon forests are being degraded by myriad anthropogenic disturbances, altering ecosystem and climate function. We analyzed the effects of a range of land-use and climate-change disturbances on fine-scale canopy structure using a large database of profiling canopy lidar collected from disturbed and mature Amazon forest plots. At most of the disturbed sites, surveys were conducted 10–30 years after disturbance, with many exhibiting signs of recovery. Structural impacts differed in magnitude more than in character among disturbance types, producing a gradient of impacts. Structural changes were highly coordinated in a manner consistent across disturbance types, indicating commonalities in regeneration pathways. At the most severely affected site – burned igapó (seasonally flooded forest) – no signs of canopy regeneration were observed, indicating a sustained alteration of microclimates and consequently greater vulnerability to transitioning to a more open-canopy, savanna-like state. Notably, disturbances rarely shifted forests beyond the natural background of structural variation within mature plots, highlighting the similarities between anthropogenic and natural disturbance regimes, and indicating a degree of resilience among Amazon forests. Studying diverse disturbance types within an integrated analytical framework builds capacity to predict the risk of degradation-driven forest transitions.Fil: Smith, Marielle N.. Bangor University; Reino Unido. Michigan State University; Estados UnidosFil: Stark, Scott C.. Michigan State University; Estados UnidosFil: Taylor, Tyeen C.. University of Michigan; Estados UnidosFil: Schietti, Juliana. Universidade Federal Do Amazonas; Brasil. Ministério da Ciência, Tecnologia, Inovações. Instituto Nacional de Pesquisas da Amazônia; BrasilFil: de Almeida, Danilo Roberti Alves. Universidade de Sao Paulo; BrasilFil: Aragón, Susan. Universidade Federal Do Oeste Do Pará; BrasilFil: Torralvo, Kelly. Ministério da Ciência, Tecnologia, Inovações. Instituto Nacional de Pesquisas da Amazônia; BrasilFil: Lima, Albertina P.. Ministério da Ciência, Tecnologia, Inovações. Instituto Nacional de Pesquisas da Amazônia; BrasilFil: de Oliveira, Gabriel. University Of South Alabama; Estados UnidosFil: de Assis, Rafael Leandro. University of Oslo; Noruega. Ministério da Ciência, Tecnologia, Inovações. Instituto Nacional de Pesquisas da Amazônia; BrasilFil: Leitold, Veronika. University of Maryland; Estados UnidosFil: Pontes-Lopes, Aline. Instituto Nacional de Pesquisas Espaciais; BrasilFil: Scoles, Ricardo. Universidade Federal Do Oeste Do Pará; BrasilFil: de Sousa Vieira, Luciana Cristina. Instituto Nacional de Pesquisas Espaciais; BrasilFil: Resende, Angelica Faria. Universidade de Sao Paulo; BrasilFil: Coppola, Alysha I.. ETH Zurich. Geological Institute Biogeosciences; SuizaFil: Brandão, Diego Oliveira. Ministério da Ciência, Tecnologia, Inovações. Instituto Nacional de Pesquisas da Amazônia; BrasilFil: de Athaydes Silva Junior, João. Universidade Federal do Pará; BrasilFil: Lobato, Laura F.. Universidade Federal Do Oeste Do Pará; BrasilFil: Freitas, Wagner. Universidade Federal Do Oeste Do Pará; BrasilFil: Almeida, Daniel. Universidade Federal Do Oeste Do Pará; BrasilFil: Souza, Mendell S.. Universidade Federal Do Oeste Do Pará; BrasilFil: Minor, David M.. University of Maryland; Estados UnidosFil: Villegas, Juan Camilo. Universidad de Antioquia; ColombiaFil: Law, Darin J.. University of Arizona; Estados UnidosFil: Gonçalves, Nathan. Michigan State University; Estados UnidosFil: da Rocha, Daniel Gomes. The Mamirauá Sustainable Development Institute; Brasil. University of California at Davis; Estados UnidosFil: Guedes, Marcelino Carneiro. Ministerio da Agricultura Pecuaria e Abastecimento de Brasil. Empresa Brasileira de Pesquisa Agropecuaria; BrasilFil: Tonini, Hélio. Embrapa Pecuária Sul; BrasilFil: da Silva, Kátia Emídio. Ministerio da Agricultura Pecuaria e Abastecimento de Brasil. Empresa Brasileira de Pesquisa Agropecuaria; BrasilFil: van Haren, Joost. University of Arizona; Estados UnidosFil: Rosa, Diogo Martins. Ministério da Ciência, Tecnologia, Inovações. Instituto Nacional de Pesquisas da Amazônia; BrasilFil: do Valle, Dalton Freitas. Ministério da Ciência, Tecnologia, Inovações. Instituto Nacional de Pesquisas da Amazônia; BrasilFil: Cordeiro, Carlos Leandro. Instituto Internacional Para Sustentabilidade; BrasilFil: de Lima, Nicolas Zaslavsky. Universidade Federal Do Oeste Do Pará; BrasilFil: Shao, Gang. Michigan State University; Estados Unidos. Purdue University Libraries And School Of Information Studies; Estados UnidosFil: Menor, Imma Oliveras. University of Oxford; Reino UnidoFil: Conti, Georgina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Florentino, Ana Paula. Ministério da Ciência, Tecnologia, Inovações. Instituto Nacional de Pesquisas da Amazônia; BrasilFil: Montti, Lía. Universidad Nacional de Mar del Plata; ArgentinaFil: Aragão, Luiz. Instituto Nacional de Pesquisas Espaciais; BrasilFil: McMahon, Sean M.. Smithsonian Environmental Research Center; Estados UnidosFil: Parker, Geoffrey G.. Smithsonian Environmental Research Center; Estados UnidosFil: Breshears, David D.. University of Arizona; Estados UnidosFil: Da Costa, Antonio Carlos Lola. Universidade Federal do Pará; BrasilFil: Magnusson, William E.. Ministério da Ciência, Tecnologia, Inovações. Instituto Nacional de Pesquisas da Amazônia; BrasilFil: Mesquita, Rita. Ministério da Ciência, Tecnologia, Inovações. Instituto Nacional de Pesquisas da Amazônia; BrasilFil: Camargo, José Luís C.. Ministério da Ciência, Tecnologia, Inovações. Instituto Nacional de Pesquisas da Amazônia; BrasilFil: de Oliveira, Raimundo C.. Embrapa Amazônia Oriental; BrasilFil: de Camargo, Plinio B.. Universidade de Sao Paulo; BrasilFil: Saleska, Scott R.. University of Arizona; Estados UnidosFil: Nelson, Bruce Walker. Ministério da Ciência, Tecnologia, Inovações. Instituto Nacional de Pesquisas da Amazônia; Brasi

Initial invasive or conservative strategy for stable coronary disease

BACKGROUND Among patients with stable coronary disease and moderate or severe ischemia, whether clinical outcomes are better in those who receive an invasive intervention plus medical therapy than in those who receive medical therapy alone is uncertain. METHODS We randomly assigned 5179 patients with moderate or severe ischemia to an initial invasive strategy (angiography and revascularization when feasible) and medical therapy or to an initial conservative strategy of medical therapy alone and angiography if medical therapy failed. The primary outcome was a composite of death from cardiovascular causes, myocardial infarction, or hospitalization for unstable angina, heart failure, or resuscitated cardiac arrest. A key secondary outcome was death from cardiovascular causes or myocardial infarction. RESULTS Over a median of 3.2 years, 318 primary outcome events occurred in the invasive-strategy group and 352 occurred in the conservative-strategy group. At 6 months, the cumulative event rate was 5.3% in the invasive-strategy group and 3.4% in the conservative-strategy group (difference, 1.9 percentage points; 95% confidence interval [CI], 0.8 to 3.0); at 5 years, the cumulative event rate was 16.4% and 18.2%, respectively (difference, 121.8 percentage points; 95% CI, 124.7 to 1.0). Results were similar with respect to the key secondary outcome. The incidence of the primary outcome was sensitive to the definition of myocardial infarction; a secondary analysis yielded more procedural myocardial infarctions of uncertain clinical importance. There were 145 deaths in the invasive-strategy group and 144 deaths in the conservative-strategy group (hazard ratio, 1.05; 95% CI, 0.83 to 1.32). CONCLUSIONS Among patients with stable coronary disease and moderate or severe ischemia, we did not find evidence that an initial invasive strategy, as compared with an initial conservative strategy, reduced the risk of ischemic cardiovascular events or death from any cause over a median of 3.2 years. The trial findings were sensitive to the definition of myocardial infarction that was used

Health-status outcomes with invasive or conservative care in coronary disease

BACKGROUND In the ISCHEMIA trial, an invasive strategy with angiographic assessment and revascularization did not reduce clinical events among patients with stable ischemic heart disease and moderate or severe ischemia. A secondary objective of the trial was to assess angina-related health status among these patients. METHODS We assessed angina-related symptoms, function, and quality of life with the Seattle Angina Questionnaire (SAQ) at randomization, at months 1.5, 3, and 6, and every 6 months thereafter in participants who had been randomly assigned to an invasive treatment strategy (2295 participants) or a conservative strategy (2322). Mixed-effects cumulative probability models within a Bayesian framework were used to estimate differences between the treatment groups. The primary outcome of this health-status analysis was the SAQ summary score (scores range from 0 to 100, with higher scores indicating better health status). All analyses were performed in the overall population and according to baseline angina frequency. RESULTS At baseline, 35% of patients reported having no angina in the previous month. SAQ summary scores increased in both treatment groups, with increases at 3, 12, and 36 months that were 4.1 points (95% credible interval, 3.2 to 5.0), 4.2 points (95% credible interval, 3.3 to 5.1), and 2.9 points (95% credible interval, 2.2 to 3.7) higher with the invasive strategy than with the conservative strategy. Differences were larger among participants who had more frequent angina at baseline (8.5 vs. 0.1 points at 3 months and 5.3 vs. 1.2 points at 36 months among participants with daily or weekly angina as compared with no angina). CONCLUSIONS In the overall trial population with moderate or severe ischemia, which included 35% of participants without angina at baseline, patients randomly assigned to the invasive strategy had greater improvement in angina-related health status than those assigned to the conservative strategy. The modest mean differences favoring the invasive strategy in the overall group reflected minimal differences among asymptomatic patients and larger differences among patients who had had angina at baseline