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Because freshwater covers such a small fraction of the Earth’s surface area, inland freshwater ecosystems (particularly lakes, rivers, and reservoirs) have rarely been considered as potentially important quantitative components of the carbon cycle at either global or regional scales. By taking published estimates of gas exchange, sediment accumulation, and(More)
Decomposition rate constants were measured for boles of 155 large dead trees (>10 cm diameter) in central Amazon forests. Mortality data from 21 ha of permanent inventory plots, monitored for 10–15 years, were used to select dead trees for sampling. Measured rate constants varied by over 1.5 orders of magnitude (0.015–0.67 year–1), averaging 0.19 year–1(More)
Terrestrial ecosystems in the humid tropics play a potentially important but presently ambiguous role in the global carbon cycle. Whereas global estimates of atmospheric CO2 exchange indicate that the tropics are near equilibrium or are a source with respect to carbon, ground-based estimates indicate that the amount of carbon that is being absorbed by(More)
One of the major impediments to the integration of lentic ecosystems into global environmental analyses has been fragmentary data on the extent and size distribution of lakes, ponds, and impoundments. We use new data sources, enhanced spatial resolution, and new analytical approaches to provide new estimates of the global abundance of surface-water bodies.(More)
Detecting human impacts on riverine systems is challenging because of the diverse biological, chemical, hydrological and geophysical components that must be assessed. We briefly review the chemical, biotic, hydrologic and physical habitat assessment approaches commonly used in riverine systems. We then discuss how landscape indicators can be used to assess(More)
AbstruclFloodplain inundation and vegetation along the Negro and Amazon rivers near Manaus, Brazil were accurately delineated using multi-frequency, polarimetric synthetic aperture radar (SAR) data from the April and October 1994 SIR-C missions. A decision-tree model was used to formulate rules for a supervised classification into five categories: water,(More)
Long-term measurements (1983–2001) of nutrients and seston in Emerald Lake (Sierra Nevada, California) have revealed ecologically significant patterns. Nitrate, both during spring runoff and during growing seasons, declined from 1983 through 1995. Declining snowmelt nitrate was caused primarily by changes in snow regime induced by the 1987–1992 drought:(More)
The soda lakes of tropical Africa are recognized as among the world's most productive ecosystems (e.g., Likens 1975; Cole 1979) largely on the basis of the work of Talling et al. (1973) and Melack & Kilham (1974). These investigators reported exceptionally high rates of photosynthesis derived from dissolved oxygen changes in bottles and in free water. For(More)