993 resultados para Rocky Mountain locust.


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From left to right: Ursula, Walter, Hal, Kurt, Fritz, and Elizabeth Gottschalk; the lake is probably the Titisee near the Swiss border in the Black Forest, Germany

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Front left to right: Ursula and Walter; back left to right: Kurt, Elizabeth, and Hal

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From left to right: Ursula, Walter, Hal, Kurt, Fritz, and Elizabeth Gottschalk; the lake is probably the Titisee near the Swiss border in the Black Forest, Germany

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Aims of this thesis This study is part of a larger hare project in Finland, which provides answers to basic ecological questions regarding the mountain hare. This study of the ecology of the mountain hare focuses in particular on different levels of managed boreal forest. The feeding habits and intensity of mountain hares in winter are explored, and the connections between mountain hares versus the forest structure are also studied (e.g. habitat use and the importance of different forest layers for hares). The use of the environment by hares at the landscape level was examined (forest patch structures), and the home ranges of mountain hares were studied. Finally, the productivity and survival rate of mountain hare populations were also studied (discussion e.g. predator effects on hare populations). Conclusions Feeding intensity seemed to be highest in the spring-winter, when home ranges were also largest. Favourable food species are covered by snow in winter and the mobility of hares is highest during late winter. A shortage of suitable food species may be problematic for hares, especially during the winter period. In this study mountain hares preferred a dense shrub layer at local level and deciduous and mixed tree forest over coniferous forest at the landscape level. Food and shelter are vital for hares and the preference for particular habitats may also affect the population dynamics of the mountain hare. It would be possible to improve the quality of food and shelter or at least prevent the most negative habitat changes through forest management. At a local level it is also possible to add supplementary food for hares through the winter period. The intensive clearing of young sapling stands and especially the removal of deciduous shrubs and trees reduces the quality of habitats for the mountain hare. Mountain hares primarily live in forest habitat and it is possible that changes in the forest structure play a crucial role in mountain hare habitat preference. Ecological knowledge of the mountain hare is vital to create habitat structure more suitable for the species. More deciduous trees should be saved in managing forests and the mechanical clearing of the shrub layer should be done carefully.

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The objective of this study is to examine the social impacts of the integrated conservation and development project (ICDP) aimed at biodiversity conservation and local socio-economic development in the Ranomafana National Park (RNP), Madagascar. Furthermore, the study explores social sustainability and justice of the ICDP in Ranomafana. This ethnographically informed impact study uses of various field methods. The research material used consists of observation, interviews (key-person and focus group), school children's writings, official statistics and project documents. Fieldwork was conducted in three phases in 2001, 2002 and 2004 in twelve villages around the park, as well as in neighbouring areas of Ranomafana. However, four of those twelve villages were chosen for closer study. This study consists of five independent articles and a concluding chapter. Social impacts were studied through reproductive health indicators as well as a life security approach. Equity and distribution of benefits and drawbacks of ICDP were analysed and the actors related to the conservation in Ranomafana were identified. The children and adolescents' environmental views were also examined. The reproductive health indicators studied showed a poor state of reproductive health in the park area. Moreover, the existing social capital in the villages seemed to be fragmented due to economic difficulties that were partly caused by the conservation regulations. The ICDP in Ranomafana did not pay attention to the heterogeneity of the affected communities even though the local beneficiaries of the ICDP varied according to their ethnicity, living place, wealth, social position and gender. In addition, various conservation actors (local people in various groups, local authorities, tourist business owners, conservation NGOs and scientists) contest their interests over the forest, conservation and its related activities. This study corroborates the same type of evidence and conclusions discussed in other similar cases elsewhere: so called social conservation programmes still cannot meet the needs of the people living near the protected areas; on the contrary, they even have a reverse impact on the people's lives. A fundamental misunderstood assumption in the conservation process in Ranomafana was to consider the local people as a problem for biodiversity conservation. Major reasons for the failure of the ICDP in Ranomafana include a lack of local institutions that would have been able to communicate as equals with the conservation NGOs as well as to transfer the tradition of the authoritarian governance in conservation management together with the over-appreciation of scientific biodiversity, and lack of will to understand the local people's rights to use the forest for their livelihoods.

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ABSTRACT The Baltic Sea is a vulnerable ecosystem currently undergoing a number of changes, both natural and human induced. The changes are likely to affect the species found on these shores, e.g. their distribution and interactions with other species. Blue mussels (Mytilus trossulus x Mytilus edulis) provide one of the main biogenic hard structures on the shallow shores of the Baltic Sea where they aggregate into dense beds and provide a number of resources for over 40 associated macrofaunal species, thus functioning as ecosystem engineers. The blue mussel, being a marine species, is highly likely to be affected by any changes in sea water salinity, circulation and/or water balance. These changes could trickle down also to affect the associated macrofaunal communities. The aims of this thesis were three-fold: first, I examined and described the macrofaunal communities found within blue mussel patches since the fauna associated with mussel patches had never been described in the study area prior to this thesis. Second, I explored how changes in mussel density, size as well as patch size and shape would affect the mussel communities. Finally, I tested how general landscape theories derived from terrestrial studies function in blue mussel systems. Theories included the structural heterogeneity hypothesis, species-area relationships, edge effects and patch isolation effects. The work shows that blue mussels in the northern Baltic Sea have an indisputable function as diversity hotspots and that the faunal assemblages found in mussel patches are extremely rich and unique. Further on, it shows that changes in mussel biomass, size, patch size and amount of edge have the potential to alter the faunal assemblages and diversity within patches. Finally, it shows that although some landscape theories, such as the structural heterogeneity hypothesis, seem to apply also in blue mussel communities, others cannot be directly applied due to the different prevailing conditions in the study system. This is a pioneering work looking at diversity shaping processes on the rocky shores of the Gulf of Finland, making up over 40% of the total water basin. A focus on niche construction, positive facilitation effects and ecosystem engineering could provide new insights and methods for conservation biology, but before this can be done, we need to fully understand the circumstances under which a species becomes an ecosystem engineer and recognize the systems in which it functions.

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Mountain waves in the stratosphere have been observed over elevated topographies using both nadir-looking and limb-viewing satellites. However, the characteristics of mountain waves generated over the Himalayan Mountain range and the adjacent Tibetan Plateau are relatively less explored. The present study reports on three-dimensional (3-D) properties of a mountain wave event that occurred over the western Himalayan region on 9 December 2008. Observations made by the Atmospheric Infrared Sounder on board the Aqua and Microwave Limb Sounder on board the Aura satellites are used to delineate the wave properties. The observed wave properties such as horizontal (lambda(x), lambda(y)) and vertical (lambda(z)) wavelengths are 276 km (zonal), 289 km (meridional), and 25 km, respectively. A good agreement is found between the observed and modeled/analyzed vertical wavelength for a stationary gravity wave determined using the Modern Era Retrospective Analysis for Research and Applications (MERRA) reanalysis winds. The analysis of both the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis and MERRA winds shows that the waves are primarily forced by strong flow across the topography. Using the 3-D properties of waves and the corrected temperature amplitudes, we estimated wave momentum fluxes of the order of similar to 0.05 Pa, which is in agreement with large-amplitude mountain wave events reported elsewhere. In this regard, the present study is considered to be very much informative to the gravity wave drag schemes employed in current general circulation models for this region.

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Mountain waves in the stratosphere have been observed over elevated topographies using both nadir-looking and limb-viewing satellites. However, the characteristics of mountain waves generated over the Himalayan Mountain range and the adjacent Tibetan Plateau are relatively less explored. The present study reports on three-dimensional (3-D) properties of a mountain wave event that occurred over the western Himalayan region on 9 December 2008. Observations made by the Atmospheric Infrared Sounder on board the Aqua and Microwave Limb Sounder on board the Aura satellites are used to delineate the wave properties. The observed wave properties such as horizontal (lambda(x), lambda(y)) and vertical (lambda(z)) wavelengths are 276 km (zonal), 289 km (meridional), and 25 km, respectively. A good agreement is found between the observed and modeled/analyzed vertical wavelength for a stationary gravity wave determined using the Modern Era Retrospective Analysis for Research and Applications (MERRA) reanalysis winds. The analysis of both the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis and MERRA winds shows that the waves are primarily forced by strong flow across the topography. Using the 3-D properties of waves and the corrected temperature amplitudes, we estimated wave momentum fluxes of the order of similar to 0.05 Pa, which is in agreement with large-amplitude mountain wave events reported elsewhere. In this regard, the present study is considered to be very much informative to the gravity wave drag schemes employed in current general circulation models for this region.

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In this paper, the analytical model coupling the convective boundary layer (CBL) with the free atmosphere developed by Qi and Fu (1992) is improved. And by this improved model, the interaction between airflow over a mountain and the CBL is further discussed. The conclusions demonstrate: (1) The perturbation potential temperatures in the free atmosphere can counteract the effect of orographic thermal forcing through entraining and mixing in the CBL. If u(M)BAR > u(F)BAR, the feedback of the perturbation potential temperatures in the free atmosphere is more important than orographic thermal forcing, which promotes the effect of interfacial waves. If u(M)BAR < u(F)BAR, orographic thermal forcing is more important, which makes the interfacial height and the topographic height identical in phase, and the horizontal speeds are a maximum at the top of the mountain. (2) The internal gravity waves propagating vertically in the free atmosphere cause a strong downslope wind to become established above the lee slope in the CBL and result in the hydraulic jump at the top of the CBL. (3) With the CBL deepening, the interfacial gravity waves induced by the potential temperature jump at the top of the CBL cause the airflow in the CBL to be subcritical.

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This study was designed to compare the quality of veal produced from ‘Tudanca x Charolais’ cross (n=6) and Limousin (n=6) breeds when allowed to feed freely on mountain pastures and suckle naturally from birth to 7 months of age. After 80 days of age calves also had access to concentrate (maximum of 3 Kg/day), while mothers did not. At slaughter, Limousin calves were heavier (P<0.01) and provided better carcass yield (P<0.05) and conformation (P<0.001) than Tudanca calves. Tudanca beef provided higher fat content (P<0.05) was less tough (P<0.05), and was scored as more tender and juicy (P<0.1) with higher acceptability than Limousin beef (P<0.1). In general, Tudanca had a better fatty acid profile than Limousin beef, especially in terms of the content of polyunsaturated (P<0.05), long-chain polyunsaturated fatty acids (P<0.05) and their n-6/n-3 ratios (P<0.1), as well as vaccenic acid (P<0.1) and the overall trans-18:1 isomer profile.

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Rhythmic motor behaviors in all animals appear to be under the control of "central pattern generator" circuits, neural circuits which can produce output patterns appropriate for behavior even when isolated from their normal peripheral inputs. Insects have been a useful model system in which to study the control of legged terrestrial locomotion. Much is known about walking in insects at the behavioral level, but to date there has been no clear demonstration that a central pattern generator for walking exists. The focus of this thesis is to explore the central neural basis for locomotion in the locust, Schistocerca americana.

Rhythmic motor patterns could be evoked in leg motor neurons of isolated thoracic ganglia of locusts by the muscarinic agonist pilocarpine. These motor patterns would be appropriate for the movement of single legs during walking. Rhythmic patterns could be evoked in all three thoracic ganglia, but the segmental rhythms differed in their sensitivities to pilocarpine, their frequencies, and the phase relationships of motor neuron antagonists. These different patterns could be generated by a simple adaptable model circuit, which was both simulated and implemented in VLSI hardware. The intersegmental coordination of leg motor rhythms was then examined in preparations of isolated chains of thoracic ganglia. Correlations between motor patterns in different thoracic ganglia indicated that central coupling between segmental pattern generators is likely to contribute to the coordination of the legs during walking.

The work described here clearly demonstrates that segmental pattern generators for walking exist in insects. The pattern generators produce motor outputs which are likely to contribute to the coordination of the joints of a limb, as well as the coordination of different limbs. These studies lay the groundwork for further studies to determine the relative contributions of central and sensory neural mechanisms to terrestrial walking.

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I. Foehn winds of southern California.
An investigation of the hot, dry and dust laden winds occurring in the late fall and early winter in the Los Angeles Basin and attributed in the past to the influences of the desert regions to the north revealed that these currents were of a foehn nature. Their properties were found to be entirely due to dynamical heating produced in the descent from the high level areas in the interior to the lower Los Angeles Basin. Any dust associated with the phenomenon was found to be acquired from the Los Angeles area rather than transported from the desert. It was found that the frequency of occurrence of a mild type foehn of this nature during this season was sufficient to warrant its classification as a winter monsoon. This results from the topography of the Los Angeles region which allows an easy entrance to the air from the interior by virtue of the low level mountain passes north of the area. This monsoon provides the mild winter climate of southern California since temperatures associated with the foehn currents are far higher than those experienced when maritime air from the adjacent Pacific Ocean occupies the region.

II. Foehn wind cyclo-genesis.
Intense anticyclones frequently build up over the high level regions of the Great Basin and Columbia Plateau which lie between the Sierra Nevada and Cascade Mountains to the west and the Rocky Mountains to the east. The outflow from these anticyclones produce extensive foehns east of the Rockies in the comparatively low level areas of the middle west and the Canadian provinces of Alberta and Saskatchewan. Normally at this season of the year very cold polar continental air masses are present over this territory and with the occurrence of these foehns marked discontinuity surfaces arise between the warm foehn current, which is obliged to slide over a colder mass, and the Pc air to the east. Cyclones are easily produced from this phenomenon and take the form of unstable waves which propagate along the discontinuity surface between the two dissimilar masses. A continual series of such cyclones was found to occur as long as the Great Basin anticyclone is maintained with undiminished intensity.

III. Weather conditions associated with the Akron disaster.
This situation illustrates the speedy development and propagation of young disturbances in the eastern United States during the spring of the year under the influence of the conditionally unstable tropical maritime air masses which characterise the region. It also furnishes an excellent example of the superiority of air mass and frontal methods of weather prediction for aircraft operation over the older methods based upon pressure distribution.

IV. The Los Angeles storm of December 30, 1933 to January 1, 1934.
This discussion points out some of the fundamental interactions occurring between air masses of the North Pacific Ocean in connection with Pacific Coast storms and the value of topographic and aerological considerations in predicting them. Estimates of rainfall intensity and duration from analyses of this type may be made and would prove very valuable in the Los Angeles area in connection with flood control problems.

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Skates (family Rajidae) are oviparous and lay tough, thick-walled eggs. At least some skate species lay their eggs in spatially restricted nursery grounds where embryos develop and hatch (Hitz, 1964; Hoff, 2007). After hatching, neonates may quickly leave the nursery grounds (Hoff, 2007). Egg densities in these small areas may be quite high. As an example, in the eastern Bering Sea, a site <2 km2 harbored eggs of Alaska skate (Bathyraja parmifera) exceeding 500,000/km2. All skate nursery grounds have been identified over soft sea floors (Lucifora and García, 2004; Hoff, 2007).