ABSTRACT
Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models.
Subject(s)
Carbon Dioxide/analysis , Carbon Sequestration , Rainforest , Atmosphere/chemistry , Biomass , Brazil , Carbon/analysis , Carbon/metabolism , Carbon Dioxide/metabolism , Plant Stems/metabolism , Trees/growth & development , Trees/metabolism , Tropical Climate , Wood/analysisABSTRACT
The use of a Fast Track system in the emergency department is becoming increasingly popular in order to provide fast and efficient service to patients with minor emergencies. In this paper we describe the one-year results of our system staffed by nurse practitioners. During the first year of operation, a total of 4468 patients were seen in Fast Track. Approximately 28% of patients are triaged to Fast Track during its hours of operation. The average patient seen in Fast Track was ready for discharge 94.4 minutes after presentation. Fewer than 1% of patients required admission to the hospital. Overall, patients and medical staff were highly satisfied with the Fast Track system. Our experience demonstrates that nurse practitioners can effectively and efficiently staff a Fast Track in an academic emergency department.
