High Mountain Range Research Articles

Neogene uplift of the Tian Shan Mountains observed in the magnetic record of the Jingou River section (northwest China)

The Tian Shan Mountains constitute central Asia's longest and highest mountain range. Understanding their Cenozoic uplift history thus bears on mountain building processes in general, and on how deformation has occurred under the influence of the India‐Asia collision in particular. In order to help decipher the uplift history of the Tian Shan, we collected 970 samples for magnetostratigraphic analysis along a 4571‐m‐thick section at the Jingou River (Xinjiang Province, China). Stepwise alternating field and thermal demagnetization isolate a linear magnetization component that is interpreted as primary. From this component, a magnetostratigraphic column composed of 67 polarity chrons are correlated with the reference geomagnetic polarity timescale between ∼1 Ma and ∼23.6 Ma, with some uncertainty below ∼21 Ma. This correlation places precise temporal control on the Neogene stratigraphy of the southern Junggar Basin and provides evidence for two significant stepwise increases in sediment accumulation rate at ∼16–15 Ma and ∼11–10 Ma. Rock magnetic parameters also undergo important changes at ∼16–15 Ma and ∼11–10 Ma that correlate with changes in sedimentary depositional environments. Together with previous work, we conclude that growth history of the modern Tian Shan Mountains includes two pulses of uplift and erosion at ∼16–15 Ma and ∼11–10 Ma. Middle to upper Tertiary rocks around the Tian Shan record very young (<∼5 Ma) counterclockwise paleomagnetic rotations, on the order of 15° to 20°, which are interpreted as because of strain partitioning with a component of sinistral shear that localized rotations in the piedmont.

Spatial distribution and optical properties of Saharan dust observed by airborne high spectral resolution lidar during SAMUM 2006

Airborne measurements of pure Saharan dust extinction and backscatter coefficients, the corresponding lidar ratio and the aerosol optical thickness (AOT) have been performed during the Saharan Mineral Dust Experiment 2006, with a high spectral resolution lidar. Dust layers were found to range from ground up to 4–6 km above sea level (asl). Maximum AOT values at 532 nm, encountered within these layers during the DLR Falcon research flights were 0.50–0.55. A significant horizontal variability of the AOT south of the High Atlas mountain range was observed even in cases of a well-mixed dust layer. High vertical variations of the dust lidar ratio of 38–50 sr were observed in cases of stratified dust layers. The variability of the lidar ratio was attributed to dust advection from different source regions. The aerosol depolarization ratio was about 30% at 532 nm during all measurements and showed only marginal vertical variations.

Beyond Brinkmanship: Geographical Constraints and North Korea's Evolving Tactics

IntroductionKorean history has seen the rise and fall of numerous kingdoms and states on the peninsula, competing against each other and battling external threats. In many ways, North Korea today faces similar challenges to the preceding kingdoms in the northern half of the peninsula, challenges shaped in large part by geography and locations. In looking at these deeper structural elements, and the way various Korean states adapted to the geographical constraints, North Korean behavior appears less erratic and less dogmatic. The recent shift in North Korean behavior at the negotiating table, then, becomes one predicated on how far along Pyongyang is in meeting its strategic imperatives.These imperatives are less choice than necessities for survival, and in the case of North Korea, or any other preceding or succeeding Korean state in the northern half of the peninsula, they can be summed up in just a few short points:1. Maintain strong internal cohesion of the population.2. Reduce or eliminate the threat to the weak southern border, where there are few defensible geographical boundaries.3. Reduce or remove the threat to the weak points of the northern border, particularly near the western border with China.4. Use larger external powers to balance each other in order to deal with the dual security threats from maritime and land-based neighbors.How North Korea or any other Korean state deals with these issues is a matter of choice, though not all choices work equally well. That North Korea must contend with its geographical and spatial vulnerabilities, however, is not a choice if the regime and state has any plan to survive.For North Korea in the modern world, the key to nearly all its core challenges is the United States. If North Korea eventually succeeds in reshaping relations with the United States, it will have significantly reduced, if not removed, the threat from the south. It will also be able to call on the United States to act as a buffer between Korea's more immediate historical threats; Japan and China. Finally, breaking free from the constraints of the current relationship with the United States could give Pyongyang greater access to international economic, development and technology resources, which, if used effectively, could both maintain internal social cohesion and strengthen the state.Geography and Place: Constraints and ChallengesThe Korean Peninsula is a narrow, mountainous appendix on Northeast Asia, stretching out from the Chinese-Russian border into the sea, aimed at Japan. In the North is a high plateau and mountains, with two rivers stretching to the east and west coasts (the Tumen and Yalu respectively) providing definition to the border. Figure 1 shows that in the east, a series of mountain ranges, most notably the Taebaek Range, stretches not far inland along the coast, providing a natural barrier to forces invading by sea. In the south, numerous islands guard the access to the weaker lowlands of the southwest. And along the west coast stretch the more fertile plains of Korea, though high tidal fluctuation have served as a hindrance to maritime invasion (though not a foolproof hindrance, as shown by the U.S. forces landing at Incheon in 1950).North Korea, like preceding northern-Korean states, faces a more immediate challenge from the south. Rather than having a clearly defined, if somewhat vulnerable, coastline as its border, North Korea's southern border sits along ill-defined geographical barriers. There is no defensible high mountain range like in the north or east, just the relatively low rolling hills and plains that stretch from the Taedong River in Pyongyang down through the Imjin River to the Han River flowing through Seoul. In the north, the primary vulnerability is near the mouth of the Yalu River, which creates a gap in the mountainous barriers to the North and opens a historically trod pathway to the peninsula from China and Manchuria. …

Regional Contrasts in Mountain Tourism Development in the Drakensberg, South Africa

The Drakensberg is the highest mountain range in southern Africa and is considered a valuable natural and economic resource; it is also a primary tourist destination in the region. The present article compares recent tourism development and management in the well-established Royal Natal National Park (RNNP) and the adjoining Mnweni Valley, which is a developing center and former apartheid homeland. Trends in tourist characteristics, governance, and revenue streams are presented for the two centers. Although the Mnweni region has experienced significantly greater percentage growth in visitor numbers than the RNNP over the last few years, it currently lacks the capacity to ensure adequate conservation of the mountain environment. Given the considerable contrasts in mountain tourism development in the Drakensberg, it is essential to establish mountain sustainability networks and collaboration between local and regional “actors.”

MIDDLE MIOCENE GLOBAL CHANGE AND PALEOGEOGRAPHY OF PANAMA

Fossil leaves in the middle Miocene Cucaracha Formation along the Panama Canal are 10–15 cm long, thick, and entire-margined; fossil pollen is also dicot dominated, as expected for wet tropical forests. Fossil woods include palms and ring-porous dicots, with smooth bark as is found in weakly seasonal tropical climates. In contrast, late Hemingfordian to early Barstovian mammals of the Cucaracha Formation are the same as those found in Nebraska, Kansas, and Florida, where climate was drier and cooler and vegetation more open. Cucaracha paleosols reconcile these differences as evidence of a mosaic of swamps to mangal (mangrove forests) preserving plants and dry uplands preserving mammals. A dozen pedotypes represent as many vegetation types, including mangrove, fresh-water and marine-influenced swamp, early successional riparian woodland, colonizing forest, dry tropical forest, and woodland. Many paleosols have calcareous nodules, and some have pedogenic barite nodules. Depth to carbonate and paleosol thickness with carbonate indicate mean annual precipitation of 573–916 ± 147 mm and mean annual range of precipitation of 27–65 ± 22 mm. Chemical analyses of paleosol Bt horizons confirm mean annual precipitation of 296–1142 mm and mean annual temperature of 15–16 ± 4.4°C. Low precipitation and temperature estimates imply a rain shadow from a high (1400–4000 m) volcanic mountain range to the west, with continuous land connection to allow immigration of mammals from North America. Partial enclosure of the Caribbean Sea by a mountainous Panama peninsula, as well as by Antillean arcs, initiated high Caribbean marine temperature and salinity well before Pliocene isthmian closure.

FRAGILARIA NEVADENSIS SP. NOV., A NEW DIATOM TAXON FROM A HIGH MOUNTAIN LAKE IN THE SIERRA NEVADA (GRANADA, SPAIN)

A new diatom taxon, Fragilaria nevadensis Linares-Cuesta &Sanchez-Castillo, was described based on light- and electron-microscope examination. It was isolated from a high-mountain lake in the Sierra Nevada (Granada, Spain), the highest mountain range in the Iberian Peninsula. The new taxon was characterised by its valve morphology and number of striae. Morphometric analysis suggested a relationships between F. nevadensis and the F. capucina complex, which is well represented in the Sierra Nevada by the variety rumpens. The comparison of F. nevadensis morphometric data of with those of other similar species showed that they are closely related to F. capucina var. austriaca. The ecological conditions of F. nevadensis and F. capucina var. austriaca are similar, both species growing in cold mountain waters (while F. heidenii and other similar species live in different kinds of water with a wider salinity spectrum).

Atmospheric Fronts along the East Coast of Taiwan Studied by ERS Synthetic Aperture Radar Images

Abstract The existence of quasi-stationary alongshore atmospheric fronts typically located 30–70 km off the east coast of Taiwan is demonstrated by analyzing synthetic aperture radar (SAR) images of the sea surface acquired by the European Remote Sensing Satellites ERS-1 and ERS-2. For the data interpretation, cloud images from the Japanese Geostationary Meteorological Satellite GMS-4 and the American Terra satellite, rain-rate maps from ground-based weather radars, sea surface wind data from the scatterometer on board the Quick Scatterometer (QuikSCAT) satellite, and meteorological data from weather maps and radiosonde ascents have also been used. It is shown that these atmospheric fronts are generated by the collisions of the two airflows from opposing directions: one is associated with a weak easterly synoptic-scale wind blowing against the high coastal mountain range at the east coast of Taiwan and the other with a local offshore wind. At the convergence zone where both airflows collide, air is forced to move upward, which often gives rise to the formation of coast-parallel cloud bands. There are two hypotheses about the origin of the offshore wind. The first one is that it is a thermally driven land breeze/katabatic wind, and the second one is that it is wind resulting from recirculated airflow from the synoptic-scale onshore wind. Air blocked by the mountain range at low Froude numbers is recirculated and flows at low levels back offshore. Arguments in favor of and against the two hypotheses are presented. It is argued that both the recirculation of airflow and land breeze/katabatic wind contribute to the formation of the offshore atmospheric front but that land breeze/katabatic wind is probably the main cause.

Nocturnal Meso-Beta Basin and Katabatic Flows on a Midlatitude Island

Abstract A mesoscale simulation for the island of Majorca, Spain, in the western Mediterranean Sea is used to study the nocturnal system of winds under weak synoptic pressure gradients. A very high vertical resolution is used in the first 500 m above ground level to characterize with large detail the thin circulations close to ground, namely, basin and katabatic flows. It is found that the island, the basin, and the slope scales interact strongly, especially when a quasi-steady state is reached in the second part of the night. A high mountain range creates a high pressure area upwind where local winds can develop. Katabatic flows converge to the valleys where they interact with a cold pool, which is advected slowly to sea by the land–sea night-breeze effect combined with a topographic forcing. The katabatic flows experience small entrainment at the top and have well-defined characteristics. The results are partially confirmed by the observations and some satellite images.

Local nocturnal circulations in the island of Majorca: mesoscale modelling and verification

A mesoscale simulation for the island of Majorca in the Western Mediterranean Sea is used to study the nocturnal system of winds under weak synoptic pressure gradients. A very high vertical resolution is used in the first 500 meters above ground level to characterize with large detail the thin circulations close to ground, namely basin and katabatic flows. It is found that the island, the basin and the slope scales interact strongly, especially when a quasi-steady state is reached in the second part of the night. A high mountain range creates a high pressure area upwind where local winds can develop. Katabatic flows converge to the valleys, where they interact with a cold pool, which is advected slowly to sea by the land-sea night-breeze effect combined with a topographic forcing. To see how realistic is this run, the outputs are compared against available observations: data from Automatic Weather Stations and satellite images. Although verification is a difficult task, the modelled patterns of wind and temperature agree with the observed ones.

Late Pleistocene and early Holocene glaciations in Taiwanese mountains

The high mountain range of Taiwan is unglaciated at present, but numerous glacial landforms and sediments in three mountain massifs, the Nanhuta Shan, the Hsueh Shan and the Yushan, support the concept of repeated glaciations of these areas during the Pleistocene and Early Holocene. Optically stimulated luminescence (OSL) data derived from glacial and glacier-related sediments suggests a glaciation about 8.9±0.5 ka called the Nanhuta glacier advance, which could be correlated either to the Younger Dryas or the global 8.2 ka cooling event (Alley et al., 1997. Holocene climatic instability: a prominent, widespread event 8200 yr ago. Geology 25(6), 483–486). Absolute data from pre-Holocene sediments are still rare, although glacial evidence (valley shape, erratic boulders, glacial trimlines and sediments) indicates a larger extent of valley glaciers during the Pleistocene.

Present and former equilibrium line altitudes in the Taiwanese high mountain range

Previously reported values of former equilibrium line altitudes (ELA) for Taiwan are based on sparse field data or extrapolations from Japan or China. This paper presents new calculations based on recently obtained geological data (Hebenstreit, R, Böse, M, 2003. Geomorphological evidence for a Late Pleistocene glaciation in the high mountains of Taiwan dated with age estimates by optically stimulated luminescence (OSL). Zeitschrift für Geomorphologie N.F. Suppl.-Bd.130, 31–49; Hebenstreit, R., Murray, A.S., Böse, M., this vol. Late Pleistocene and Early Holocene glaciations in Taiwanese mountains. Quaternary International) from three Taiwanese mountain massifs ( Nanhuta Shan, Hsueh Shan and Yushan) using established calculation methods (Benn, D.I., Lehmkuhl, F., 2000. Mass balance and equilibrium-line altitudes of glaciers in high-mountain environments. Quaternary International 65–66, 15–29; Porter, S.C., 2001. Snowline depression in the tropics during the Last Glaciation. Quaternary Science Reviews 20(10), 1067–1091). The relationship of annual precipitation and summer (JJA) temperature (Ohmura, A., Kasser, P., Funk, M., 1992. Climate at the equilibrium line of glaciers. Journal of Glaciology 38(130), 397–411) obtained from a 30 year meteorological database is used to estimate the present theoretical (virtual) equilibrium line altitude (ELA t) at about 4000 m over the southern and 3900 m over the northern part of Taiwan. The ELA was 3350–3500 m during Late Glacial to Early Holocene time (11–8 ka). Including a minimum post-glacial mountain uplift rate of 5 mm/a (Lundberg, N., Dorsey, R.J., 1990. Rapid Quaternary emergence, uplift, and denudation of the Coastal Range, eastern Taiwan. Geology 18(7), 638–641); Lin, C.-H., 1998. Tectonic implications of an aseismic belt beneath the eastern central range of Taiwan: crustal subduction and exhumation. Journal of the Geological Society of China 41(3), 441–460) in the calculation, the ELA depression (ΔELA) was 400–550 m during this period. Data from LGM or earlier are still rare, but glacial landforms and deposits indicate the ELA position at 2775–3195 m and the ΔELA of 705–1125 m.

Simulium (Psaroniocompsa) stellatum (Diptera: Simuliidae), a new black fly from a high mountain range in southeastern Brazil

The larva, pupa, female, and male of Simulium (Psaroniocompsa) stellatum sp. n. are described and illustrated. The pupa of this new species has four gill filaments, with the dorsal primary branch bifurcating at about half the length of the ventral branch. The adult and immature stages are similar to those of species in the S. auristriatum group. Up to date, Simulium stellatum sp. n. has been found only in the high mountain range of Itatiaia National Park in southeastern Brazil. It is the second species of the subgenus S. (Psaronicompsa) recorded at elevations above 2000 m.

Cenozoic vertical motions of the Catalan Coastal Ranges (NE Spain): The role of tectonics, isostasy, and surface transport

We analyze the Cenozoic topographic evolution of the Catalan Coastal Ranges (NE Spain) and the role of fault activity, erosion, sedimentation, and isostasy in controlling uplift and subsidence. A forward numerical model constrained by an extensive geological and geophysical data set is used to examine the temporal and spatial record of Cenozoic vertical motions. We show that the effect of isostasy, erosion, and sedimentation is as important as the contribution of fault deformation to the topography of the Catalan Coastal Ranges. The model predicts that Paleogene topography generation by thrusting was compensated by erosion (up to 1.3 km) and isostatic subsidence (up to 1.2 km), resulting in a 1.2–1.9 km high mountain range by the end of compression (29 Ma). During the Neogene, strong tectonic subsidence related to normal faulting and the consequent flexural uplift (of 0.7–1.2 km), surface erosion (as much as 1.6–2.3 km), and sedimentation (up to 4.5 km) led to the present landscape configuration. Extension rates along the Barcelona fault controlled flexural uplift and, in combination with erosion and sedimentation processes, led to the migration of the topographic maximum of the Prelitoral Range toward the easternmost Ebro Basin.

The impact of glaciers on the runoff and the reconstruction of mass balance history from hydrological data in the tropical Cordillera Blanca, Perú

A 41 years series of runoff and precipitation data from the Peruvian Cordillera Blanca demonstrates the high hygric seasonality in this tropical high mountain range. In this area, glaciers have a crucial impact on runoff which is of essential importance for the highly populated and cultivated valley of the Callejon de Huaylas particularly during the dry season. Whereas the mid latitudes glacier runoff amplifies the seasonal variation of runoff, the effect of glaciers in the low latitudes is a smoothing one. It decreases clearly with the decreasing degree of glaciation. In addition, particular circumstances of this tropical environment allow the reconstruction of a glacier mass balance history from the hydrological data for the second half of the 20th century. It shows a high synchronicity with the global trend of periods with glacier mass loss and gain. Comparison with length variations of three individual glaciers indicate a rather fast reaction of these glaciers to changes in mass balance. Although the mass balance variations show some differences among the individual catchment basins, the over all trend is uniform. A general positive correlation of mass balance variations with SOI is obvious but not regular.

Ixodes (Ixodes) dicei, a new tick species (Acari: Ixodida: Ixodidae) from a lagomorph in a restricted high-altitude habitat in talamanca, Costa Rica

Ixodes (I.) dicei n. sp. (Acari: Ixodidae) is described and illustrated from males and females collected from a cottontail rabbit. This species of cottontail is poorly known and is found only in a restricted high mountain range of central Costa Rica and western Panama.

Quaternary environmental change in New Zealand: a review

The discovery that orbital variations are the driving force behind Quaternary climate change provides an impetus to set local and regional records of environmental change into the global context, a principle that has been strongly embraced by Quaternary scientists working in New Zealand. Their major achievements and significant current initiatives are reviewed here. The importance of the New Zealand Quaternary stems from its geographical context: a climatically sensitive, remote oceanic, southern location spanning 17 degrees of the mid-latitudes; an obliquely convergent plate boundary setting resulting in a high mountain range athwart the prevailing westerlies, active volcanism, a youthful and dynamic landscape, and mountains high enough to maintain glaciers today; and a remarkably short prehistory. The resultant records show marked environmental changes due not only to climatic oscillations but also to vigorous, active tectonism and volcanism. The Taupo Volcanic Zone, containing the world's strongest concentration of youthful rhyolitic volcanoes, has produced at least 10 000 km3 of magma in the last 2 Ma. Climatic interpretations of records from marine sediments in the New Zealand region, together with several long sequences of alternating marine and terrestrial sediments, indicate broad synchrony with Northern Hemisphere events (within limitations of dating), although there are differences in detail for shorter-term climatic events. It is not yet certain that glacial advances coincided precisely with those in the Northern Hemisphere or were of similar duration. Late Cainozoic glaciation commenced c. 2.6-2.4 Ma but the record of glacial deposits is fragmentary and poorly dated except for the most recent events. The Last (Otira) Glaciation, from c. 100-10 ka, was characterized by at least five glacial advances including during the Last Glacial Maximum from 25 to 15 ka, when snowlines fell by 600-800 m. New Zealand evidence for cooling during the Younger Dryas stade is equivocal whilst isotopic records from speleothems, and other data, indicate warmer and wetter conditions from 10-7 ka, broadly conforming with records from mid-latitude Northern Hemisphere locations. Future advances will require sampling at shorter timescales, improvements in the accuracy and precision of existing dating methods and the development of new ones, extension of palaeoecological techniques to cover the full potential of new Zealand's diverse biota, and a stronger emphasis on quantification of palaeoclimatic parameters.

Petrology and provenance of the Neogene Usibelli Group and Nenana Gravel; implications for the denudation history of the central Alaska Range

ABSTRACT Neogene basins exposed along the north-central flank of the Alaska Range record the geologic development of the highest mountain range in North America. Strata from these basins consist of the Miocene Usibelli Group ( 600 m thick) and the Pliocene Nenana Gravel ( 1000 m thick). Petrographic analyses of 54 sandstone thin sections and 36 conglomerate clast counts from one of these basins, the Healy Creek basin, delineate two distinct petrofacies. A stratigraphically older, quartz-rich petrofacies defines the Healy Creek, Suntrana, and Lignite Creek Formations of the Usibelli Group. A stratigraphically younger, lithic-rich petrofacies defines the Nenana Gravel. Sandstones of the lower petrofacies are characterized by a dominance of quartz (Q60F27L12; Qm33F28Lt39) and a high proportion of polycrystalline quartz (Qp68Lvm21Lsm11). Schist and quartz clasts are common in conglomerates from this petrofacies. Imbricated conglomerate clasts and planar cross-stratification indicate southward to southwestward paleoflow for this quartz-rich petrofacies. Relative to the lower petrofacies, sandstones of the upper petrofacies are defined by a dominance of lithic fragments (Q3919L43; Qm16F21Lt63), a lower proportion of polycrystalline quartz, and a higher proportion of volcanic lithic fragments (Qp37Lvm55Lsm8). Conglomerate clast compositions in this petrofacies consist mainly of sedimentary and igneous clasts. This lithic rich petrofacies is dominated by northward paleocurrent indicators. The compositional and paleocurrent data of the Usibelli Group and Nenana Gravel suggest a regional paleodrainage reversal from southward-flowing fluvial systems transporting sediment from the quartz-rich, metamorphic Yukon-Tanana terrane, to northward-flowing fluvial systems transporting sedimentary and igneous detritus from the growing Alaska Range. Superimposed on the first-order tectonic signal are second-order compositional differences. These differences may be related to a combination of factors but appear to be consistent with well documented changes in paleoclimate. For example, sandstones deposited during the warmest and wettest paleoclimates are characterized by a relative enrichment in quartz, especially polycrystalline quartz (Healy Creek Formation, Q81F16L3, Qp93Lvm3Lsm4; Suntrana Formation, Q61F25L14, Qp66Lvm25Lsm9). Sandstones deposited during cooler and drier climates, in contrast, have lower proportions of quartz and higher proportions of feldspar and lithic fragments (Lignite Creek Formation, Q45F33L14, Qp56Lvm28Lsm17). Our analysis cannot account for all the possible influences on sandstone compositions during deposition of the Usibelli Group, but we contend that the apparent correlation between sandstone composition and changes in paleoclimate suggest that climatic modification of sandstone composition may have been significant.

Crustal Shortening on the Margins of the Tien Shan, Xinjiang, China

We present the results of mapping selected cross-sections across the margins of the Chinese Tien Shan, an intracontinental mountain belt that formed in response to the India-Eurasia collision. This belt contains significant lateral variation in topography, structure, and stratigraphy at all scales, and our estimated rates of shortening also reveal a distribution of shortening that varies laterally. At the largest scale, it consists of two major high mountain ranges in the west that merge eastward into a complex, single high mountain belt with several distinct ranges, then separates farther eastward into several low mountain ranges in the south and a single narrow high mountain range in the north. Active fold-and-thrust belts along parts of the north and south flanks of the Tien Shan involve only Mesozoic and Cenozoic sedimentary cover, which varies in both stratigraphy and structure from east to west. The southern fold-and-thrust belt decreases in width and complexity from west to east and ends before rea...

Influence of altitude on adult emergence and dynamics ofKaltenbachiola strobi (Winnertz) (Diptera: Cecidomyiidae) populations and its parasites in the Tatra National Park, Poland

A field study onKaltenbachiola strobi (Winnertz) (Diptera: Cecidomyiidae), was carried out between 1987 and 1993 in the highest mountain range in the Western Carpathians located within the Tatra National Park, in southern Poland. Rearing and analysis of 5 780 cones ofPicea abies (L.)Karst., collected from trees growing at different altitudes, yielded 30,478 individuals ofKaltenbachiola strobi, which infested 89.10% of the cones. In case of 29.81% of cones there were more than 20 larvae ofK. strobi per cone. It was shown thatK. strobi in the Tatra Mts. is more abundant in spruce stands of the upper mountain forest zone. Significant connections between the time of cone infestation byK. strobi and its parasitoids and characteristic phenophases in spruce foliage and cone development, and also the development of selected vegetation of the forest floor at different heights above sea level were determined. It was shown that the population dynamics ofK. strobi had tendency to alternate the increase and decrease in numbers every two years. It was also discovered that every two years spruce cones were inhabited by the population ofK. strobi with increased percentage of individuals having prolonged diapause. In total, the parasitoids reduced the population ofK. strobi by about 16–22.63%. Parasitism ofK. strobi in the lower mountain forest zone was higher than in the upper zone.Triplatygaster contorticornis Ratz. (Hymenoptera: Platygasteridae),Torymus azureus Boheman (Hymenoptera: Torymidae) andTetrastichus strobilanae Ratz. (Hymenoptera: Eulophidae) were most effiecient in reduction of the population ofK. strobi, and in the lower mountain forest zoneT. azureus was the dominant parasitoid species, while in the upper zoneT. contorticornis andT. strobilanae. It was shown that a considerable part of the populations ofT. azureus, T. contorticornis andT. strobilanae have their diapause prolonged and highly synchronized with the diapause of their host.

Regional Snowfall Patterns in the High, Arid Andes

Since 1990 the project ’Climate Change in the Arid Andes‘ has been focusing on past climate and environmental conditions in the high mountain range of the north Chilean Andes (18° S–28° S). The extreme aridity of this region is shown by the absence of glaciers, even at the highest altitudes above 6700 m a.s.l. More knowledge of the present climatic situation is needed to interpret the proxy data of different paleoarchives in this transition belt between tropical and extratropical circulation. Precipitation events in this arid region are mainly registered during southern hemisphere summer, when the ITCZ reaches its southernmost position. Winter precipitation (snowfall) has so far not been considered an important factor in the hydrologic system of the area, because snow is seldom accurately registered by climatic stations. To fill this gap in our information, winter snowfall activity was analysed for a period of 6 years using digital NOAA/AVHRR satellite data. The results show that snowfall during winter (May–September) is a quite regular phenomenon, mainly linked to northward displacements or cut-offs of cold air-masses from the Pacific. The areal distribution of snowfall is determined by the synoptic situation that produces precipitation. During cold frontal events, snowfall is most frequent in the southernmost part of the research area and on the western Chilean side of the Andes. Cold air that has been cut off from the westerlies often interacts with warmer and more humid air over the continent and therefore gives rise to a different snowfall distribution, with the greatest snowfall frequency between 23° S–25° S, decreasing polewards as well as towards the equator. These two winter snowfall patterns show that reconstruction of paleoclimate has to take into account the different mechanisms that may cause precipitation in the research area. Intensification of winter precipitation (e.g., the west wind zone) can induce largely different precipitation patterns, depending on which mechanisms (cut-offs, cold-fronts or both) within the west wind zone are strengthened.