THE ARCHIVES OF THE ASSOCIATION OF AMERICAN GEOGRAPHERS     

Ralph E. Ehrenberg 《The Professional geographer》1976,28(2):181-185

  相似文献   

FRENCH-CANADIAN SETTLEMENT IN VERMONT PRIOR TO THE CIVIL WAR     

Ralph D. Vicero 《The Professional geographer》1971,23(4):290-294

  相似文献   

Forest Carbon Dynamics in the Pacific Northwest (USA) and the St. Petersburg Region of Russia: Comparisons and Policy Implications     

Ralph J. Alig  Olga Krankina  Andrew Yost  Julia Kuzminykh 《Climatic change》2006,79(3-4):335-360

Forests of the United States and Russia can play a positive role in reducing the extent of global warming caused by greenhouse gases, especially carbon dioxide. To determine the extent of carbon sequestration, physical, ecological, economic, and social issues need to be considered, including different forest management objectives across major forest ownership groups. Private timberlands in the U.S. Pacific Northwest are relatively young, well stocked, and sequestering carbon at relatively high rates. Forests in northwestern Russia are generally less productive than those in the Northwestern U.S. but cover extensive areas. A large increase in carbon storage per hectare in live tree biomass is projected on National Forest timberlands in the U.S. Pacific Northwest for all selected scenarios, with an increase of between 157–175 Mg by 2050 and a near doubling of 1970s levels. On private timberlands in the Pacific Northwest, average carbon in live tree biomass per hectare has been declining historically but began to level off near 65 Mg in 2000; projected levels by 2050 are roughly what they were in 1970 at approximately 80 Mg. In the St. Petersburg region, average carbon stores were similar to those on private lands in the Pacific Northwest: 57 Mg per hectare in 2000 and ranging from 40 to 64 Mg by 2050. Although the projected futures reflect a broad range of policy options, larger differences in projected carbon stores result from the starting conditions determined by ownership, regional environmental conditions, and past changes in forest management. However, an important change of forest management objective, such as the end of all timber harvest on National Forests in the Pacific Northwest or complete elimination of mature timber in the St. Petersburg region, can lead to substantial change in carbon stores over the next 50 years.  相似文献   

Low-latitude “dusty events” vs. high-latitude “icy Heinrich events”     

Elsa Jullien  Francis Grousset  Bruno Malaiz  Josette Duprat  Maria Fernanda Sanchez-Goni  Frdrique Eynaud  Karine Charlier  Ralph Schneider  Aloys Bory  Viviane Bout  Jose Abel Flores 《Quaternary Research》2007,68(3):379-386

It has been proposed that tropical events could have participated in the triggering of the classic, high-latitude, iceberg-discharge Heinrich events (HE). We explore low-latitude Heinrich events equivalents at high resolution, in a piston core recovered from the tropical north-western African margin. They are characterized by an increase of total dust, lacustrine diatoms and fibrous lacustrine clay minerals. Thus, low-latitude events clearly reflect severe aridity events that occurred over Africa at the Saharan latitudes, probably induced by southward shifts of the Inter Tropical Convergence Zone. At a first approximation, it seems that there is more likely synchronicity between the high-latitude Heinrich Events (HEs) and low-latitude events (LLE), rather than asynchronous behaviours.  相似文献   

The tsunami model of the origin of ring structures concentric with large lunar craters     

Ralph B. Baldwin 《Physics of the Earth and Planetary Interiors》1972,6(5):327-339

The largest lunar craters are normally surrounded by one or more ring anticlines which are accompanied on their inner edges by ring synclines.  相似文献   

Distribution of Cd,Co, Cu,Fe, Mn,Ni, Pb and Zn in dissolved and particulate solids from two streams in Tennessee     

Ralph M. Perhac 《Journal of Hydrology》1972

  相似文献   

Relation between the crystal content and the chemical composition of welded tuffs     

Donald W. Peterson  Ralph J. Roberts 《Bulletin of Volcanology》1963,26(1):113-123

  相似文献   

Atrazine in a Stream-Aquifer System: Transport of Atrazine and Its Environmental Impact Near Ashland, Nebraska     

Darryl A. Blum  James D. Carr  Ralph K. Davis  Darryll T. Pederson 《Ground Water Monitoring & Remediation》1993,13(2):125-133

Lincoln's municipal wellfield consists of 44 wells located adjacent to the Platte River near Ashland, Nebraska. The herbicide atrazine was monitored in the river and two transects of monitoring, wells. The amount of atrazine transported down the Platte River in 1989, 1990, and 1991 was shown to increase each year. Induced recharge from the Platte River results in movement of atrazine from the river into the aquifer. A 21-day lag time was determined for the movement of atrazine from the river to a transect of monitoring wells 10 feet West of the bank. The role that colloids play on the transport of atrazine was determined to be insignificant. A small percentage of atrazine found in the river was determined to come from rain water. The infiltration of agrichemical-contaminated river water was shown to significantly reduce the quality of raw water and finished water being produced by the adjacent aquifer.  相似文献   

Survival and movements of Magellanic penguins rehabilitated from oil fouling along the coast of South America, 2000-2010     

Ruoppolo V  Vanstreels RE  Woehler EJ  Heredia SA  Adornes AC  da Silva-Filho RP  Matus R  Poleschi C  Griot K  Kolesnikovas CK  Serafini P 《Marine pollution bulletin》2012,64(7):1309-1317

Oil pollution is a significant conservation concern. We examined data from six institutions along the coast of South America: Emergency Relief Team of the International Fund for Animal Welfare, Fundación Mundo Marino, Centro de Recupera??o de Animais Marinhos, Natura Patagonia, Associa??o R3 Animal, and Mar del Plata Aquarium and data from resightings in Argentina, Brazil, Chile and Falkland/Malvinas Islands. From 2000 to 2010, 2183 oiled Magellanic penguins were rehabilitated as part of the routine activities of these institutions or during emergency responses to eight oil spills in which they were involved; all rehabilitated penguins were flipper banded and released. Since their release, 41 penguins were resighted until 31 December 2011. The results demonstrate that, when combined with other prevention strategies, the rehabilitation of Magellanic penguins is a strategy that contributes to the mitigation of adverse effects of oil spills and chronic pollution to the species.  相似文献   

Lack of association between color morphs of the Jellyfish Cassiopea andromeda and zooxanthella clade     

Kathrin P. Lampert  Patrick Bürger  Sebastian Striewski  Ralph Tollrian 《Marine Ecology》2012,33(3):364-369

Understanding the ecology and evolution of the cnidarian-algal symbiosis is of major scientific interest as it is sensitive to temperature and strong light and may therefore be susceptible to climate change. The stability of this mutualism is often mediated by host color pigments that influence photosynthetic activity in symbiotic dinoflagellates either by providing the photosystem with irradiance of suitable wavelength or by protecting it from much too much and potentially damaging light. Like scleractinian corals, the upside-down jellyfish, Cassiopea andromeda, relies heavily on the nutrients provided by its symbionts of the dinoflagellate genus Symbiodinium. It occurs in several conspicuously different color morphs and is found in habitats with high levels of irradiation. We tested whether the color morphs of Cassiopea were correlated with the Symbiodinium distribution in the host and whether host color was associated with different clades of Symbiodinium. We found that the presence of color pigment did not correlate with the distribution of Symbiodinium in the host. Symbiodinium was found in both the colored tentacles of the jellyfish and the colorless feeding tentacles. At least six different color morphs co-occurred in the very shallow waters of the Red Sea, but they all hosted a single Symbiodinium clade (clade A1). Therefore, no correlation of host color morph and Symbiodinium clade could be found. Photoaccumulative or photoprotective functions of host pigments, as proposed for some scleractinian corals, thus seem unlikely in the colored tentacles (vesicles) of the upside-down jellyfish Cassiopea andromeda.  相似文献