It's not too Late for the Harpy Eagle (Harpia harpyja): High Levels Of Genetic Diversity and Differentiation Can Fuel Conservation Programs

Article on the harpy eagle (Harpia harpyja) and how high levels of genetic diversity and differentiation can fuel conservation programs

Hydrologic variation during the last 170,000 years in the southern hemisphere tropics of South America

Despite the hypothesized importance of the tropics in the global climate system, few tropical paleoclimatic records extend to periods earlier than the last glacial maximum (LGM), about 20,000 years before present. We present a well-dated 170,000-year time series of hydrologic variation from the southern hemisphere tropics of South America that extends from modern times through most of the penultimate glacial period. Alternating mud and salt units in a core from Salar de Uyuni, Bolivia reflect alternations between wet and dry periods. The most striking feature of the sequence is that the duration of paleolakes increased in the late Quaternary. This change may reflect increased precipitation, geomorphic or tectonic processes that affected basin hydrology, or some combination of both. The dominance of salt between 170,000 and 140,000 yr ago indicates that much of the penultimate glacial period was dry, in contrast to wet conditions in the LGM. Our analyses also suggest that the relative influence of insolation forcing on regional moisture budgets may have been stronger during the past 50,000 years than in earlier times. © 2003 University of Washington. All rights reserved

North Atlantic forcing of Amazonian precipitation during the last ice age

The last glacial period was marked by multiple, abrupt reorganizations of ocean and atmosphere circulation. On thousand-year timescales, slowing of the Atlantic meridional overturning circulation was associated with cooling in the high northern latitudes, whereas strengthened circulation was linked to northern warming. In the tropics, these millennial-scale events were primarily reflected in altered patterns of precipitation. These hydrologic fluctuations induced ecological changes in the Atlantic seaboard and the high Andes, but less is known about the Amazon Basin. Here we reconstruct precipitation over Amazonian Ecuador over the past 94,000 years using a δ18O record from speleothems collected in Santiago Cave in western Amazonia. We interpret the variability of the δ18O record as changes in the source and amount of precipitation. With the exception of the period between 40,000 and 17,000 years ago, abrupt, high-frequency changes coincide with shifts in North Atlantic circulation, indicating a high-latitude influence on Amazonian precipitation over millennial timescales. On longer timescales, the record shows a relationship to precessional changes in the Earth’s orbit. In light of the lack of extreme aridity in our records, we conclude that ecosystems in western Amazonia have not experienced prolonged drying over the past 94,000 years

Changes in fire regimes since the last glacial maximum: an assessment based on a global synthesis and analysis of charcoal data

Fire activity has varied globally and continuously since the last glacial maximum (LGM) in response to long-term changes in global climate and shorter-term regional changes in climate, vegetation, and human land use. We have synthesized sedimentary charcoal records of biomass burning since the LGM and present global maps showing changes in fire activity for time slices during the past 21,000 years (as differences in charcoal accumulation values compared to pre-industrial). There is strong broad-scale coherence in fire activity after the LGM, but spatial heterogeneity in the signals increases thereafter. In North America, Europe and southern South America, charcoal records indicate less-than-present fire activity during the deglacial period, from 21,000 to ?11,000 cal yr BP. In contrast, the tropical latitudes of South America and Africa show greater-than-present fire activity from ?19,000 to ?17,000 cal yr BP and most sites from Indochina and Australia show greater-than-present fire activity from 16,000 to ?13,000 cal yr BP. Many sites indicate greater-than-present or near-present activity during the Holocene with the exception of eastern North America and eastern Asia from 8,000 to ?3,000 cal yr BP, Indonesia and Australia from 11,000 to 4,000 cal yr BP, and southern South America from 6,000 to 3,000 cal yr BP where fire activity was less than present. Regional coherence in the patterns of change in fire activity was evident throughout the post-glacial period. These complex patterns can largely be explained in terms of large-scale climate controls modulated by local changes in vegetation and fuel load