Micro-site conditions of epiphytic orchids in a human impact gradient in Kathmandu valley, Nepal

We studied distribution and site conditions of epiphytic orchids in a gradient of human interference in Kathmandu valley, central Nepal. The aim was to understand the recent distribution pattern of epiphytic orchids, with respect to (i) the micro-site conditions and (ii) the type and intensity of land use. The occurrence of epiphytic orchids was recorded for a grid with 1.5 km cell size. The cells represent different types and intensities of human impact. Site factors such as bark rugosity, bark pH, diameter at breast height (dbh; 1.3 m) of host trees, exposure to wind and sunlight intensity were recorded. With regard to the species richness and abundance of epiphytic orchids, we compared different human impact categories from very strong human impact (settlement area) to very low human impact (national park). Remote sensing was used for a supervised classification of land cover. Ficus religiosa turned out to be the most important host species for orchids in urban areas, while Schima wallichii and Alnus nepalensis significantly host orchids in the other categories. Both species richness and abundance of epiphytic orchids were significantly higher under very low human impact (forest in national park) and also some remaining patches of primary forest than the other regions. Micro-climate is crucial for orchid populations. Host bark pH, bark rugosity, sunlight intensity and host exposure were significantly different for all human impact categories in order to harbour epiphytic orchid species. Habitats with a mixture of mature trees are suitable and essential for the conservation of viable populations of epiphytic orchids in settled areas. The study reveals that to improve the population size of orchids it is essential for future urban forestry to: (i) Protect old trees as carriers of existing epiphytic orchid diversity, (ii) protect medium old trees to ensure that they may become old trees, (iii) plant new host trees for the future, (iv) plant in groups instead of single isolate trees. Trees should especially be planted in areas where orchids still exist to provide more trees for orchid population enlargement (e.g. along riparian system). Native species should be favoured; the pool of such native host species is wide.     

Observations of the 7 March, 1970 total solar eclipse at wavelengths of 3.2 and 8.3 mm

The 7 March, 1970 total solar eclipse was observed at wavelengths of 3.2 and 8.3 mm; the object being to use the knife edge of the Moon as it passed across the Sun to improve angular resolution on the Sun. This in turn would provide a radial brightness distribution of the Sun with an angular resolution of a few seconds of arc.Excellent eclipse curves were obtained at 3 mm; however, some external interference marred the 8 mm record near totality.The 8 mm brightness distribution is subject to some uncertainty, but tends to show limb brightening. The 3 mm brightness distribution shows a well defined complex limb brightening within about 1 arc min of the optical limb. The maximum brightening is approximately 30% above the average disc temperature.     

The Bidjovagge copper-gold deposits of Western Finnmark,Norway

The Bidjovagge copper-gold deposits occur in the Svecokarelian Caskias Group. The rocks in the mineralized district consist of greenstones, carbonate rocks, albite felsite and graphite felsite. Four ore bodies are found in albite felsite and graphite felsite over a strike length of 2.5 km. The ore bodies represent remobilizations from syngenetic, stratabound mineralization. Ore minerals of economic significance are chalcopyrite and native gold. An assemblage of gold and tellurides in the country rock occurs as a late stage mobilization product.

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Zusammenfassung Das Bidjovagge Kupfer-Gold-Vorkommen liegt in der Svecokarelischen Caskias-Gruppe. Die Gesteine innerhalb des mineralisierten Distriktes bestehen aus Grünsteinen, Karbonatgesteinen, Albitfelsiten und Graphitfelsiten. Vier Erzkörper wurden innerhalb der Albitfelsite und Graphitfeisite über eine streichende Länge von 2,5 km gefunden. Die Erzkörper repräsentieren Remobilisate von syngenetischen, schichtgebundenen Mineralisierungen. Erzmineralien von wirtschaftlicher Bedeutung sind Kupferkies und Gold. Verwachsungen von Gold mit Telluriden findet man in den Nebengesteinen als Mobilisationsprodukte einer späteren Phase.

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Résumé Les gisements de cuivre et d'or de Bidjovagge se trouvent dans le groupe svécokarélidien de Caskias. Les roches de ce district minier consistent en roches vertes, roches carbonatées et felsites albitiques et graphitiques. Quatre gisements de minerai ont été trouvés dans les felsites albitiques et graphitiques sur une distance de 2,5 kilomètres. Ces gisements représentent des remobilisations d'une minéralisation syngénétique sédimentaire. La chalcopyrite et l'or sont les seuls minéraux d'importance économique. Des émissions d'or et de tellurures dans les épontes paraissent être le produit d'une phase de mobilisation tardive.

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Persistence of clear-water,shallow-lake ecosystems: the role of protected areas and stable aquatic food webs

The roles of both landscape alteration and in-lake processes need to be considered in conservation strategies for shallow lakes in the prairie regions of North America. Here we focus on shallow lakes in west-central Minnesota, USA, highlighting the long-term ecological history and response to known landscape changes of a clear-water, macrophyte-dominated, shallow lake. Contemporary limnological data suggest the aquatic ecosystem has been very stable and fishless for the last ~15 years. Sediment proxies for primary production and ecological change confirm that a stable ecosystem likely prevailed for the last ~200 years. However, sedimentary indicators of catchment erosion detail a distinct response to land-use change during the conversion of native grassland to agricultural land, and following establishment of a protected waterfowl production area (WPA) around the lake. Post-WPA, the rate of sediment accrual decreased dramatically within 5–10 years and sources of organic matter were similar to those of the pre-settlement period. The aquatic ecosystem has been able to withstand nutrient enrichment and allochthonous inputs because stable trophic interactions have likely been in place for more than 200 years. We conclude that lack of hydrologic connectivity and isolated, small catchments are important factors in the promotion of clear-water shallow lake ecosystems, mainly because they prevent colonization by fish and associated ecological consequences. This study highlights the importance of managing both the landscape and in-lake processes to maintain stable, clear-water, shallow lakes.     

Diversity,composition and host-species relationships of epiphytic orchids and ferns in two forests in Nepal

Epiphytic plant species are an important part of biological diversity. It is therefore essential to understand the distribution pattern and the factors influencing such patterns. The present study is aimed at observing the patterns of species richness, abundances and species composition of epiphytic orchids and ferns in two subtropical forests in Nepal. We also studied the relationship of host plants (Schima wallichii and Quercus lanata) and epiphyte species. Data were collected in Naudhara community forest (CF) and the national forest (NF) in Shivapuri Nagarjun National Park. The data were analyzed using univariate and multivariate tests. In total, we recorded 41 species of epiphytes (33 orchid and 8 fern species). Orchid species abundance is significantly higher in CF compared to NF. Orchid species richness and abundance increased with increasing southern aspect whereas it decreased with increasing canopy cover, and fern species richness increased with host bark roughness. Orchid abundance was positively correlated with increasing bark pH, stem size, tree age and tree height and negatively correlated with increasing steepness of the area. Likewise, fern abundances were high in places with high canopy cover, trees that were tall and big, but decreased with increasing altitude and southern aspect. The composition of the orchid and fern species was affected by altitude, aspect, canopy cover, DBH, number of forks and forest management types. We showed that the diversity of orchid and fern epiphytes is influenced by host characteristics as well as host types. The most important pre-requisite for a high epiphyte biodiversity is the presence of old respectively tall trees, independent of the recent protection status. This means: (i) for protection, e.g. in the frame of the national park declaration, such areas should be used which host such old tall trees; and (ii) also in managed forests and even in intensively used landscapes epiphytes can be protected by letting a certain number of trees be and by giving them space to grow old and tall.     

Platinum-group metals and their alloys in nuggets from alluvial deposits in Finnish Lapland

Alluvial nuggets of PGE alloys from the rivers Miessijoki, Sotajoki, Puskuoja, Palsinoja and Ivalojoki at Kolmosenkoski rapids and from the Härkäselkä area have been investigated with a microprobe and a scanning electron microscope. Pt---Cu, Pd---Cu---Au and Os---Ir---Ru alloys occur as well as the main Pt---Fe alloys, both as inclusions in the Pt---Fe alloys and as separate nuggets or crystals. Limited optical properties are given. From the inclusions and associated minerals it is assumed that some of the nuggets are magmatic in origin and that others are a result of oxidative weathering. The material is rounded through transport, although the original euhedral form can often be observed.     

Large aerosol particles in cirrus type clouds

Research flights in November 1990 over the central parts of the United States, Wyoming and Colorado, were aimed to the investigation of the properties and microstructure of cirrus clouds (mainly cirrocumulus lenticularis). Among the other parameters measured on board the NCAR Saberliner were the concentration and size distribution of submicron particles and, in some cases, the particle deliquescence. For coarse insoluble particles found inside and outside of cloud elements, size distributions and morphology information were obtained by evaluating inertial impactor samples with an optical microscope and scanning electron microscope. In addition, the coarse particle composition was determined by x-ray energy spectrum analysis. The following conclusions from these measurements are:The large and coarse particle size distribution can be roughly simulated by a log-normal function with the modus around r=0.5 μm. Particle concentrations are very variable between several tenths and several particles per cm³. Particle volume distribution features a distinct maximum around 0.75 μm without a broad plateau which was observed in the case of sampling at lower altitude. Aerosol composition heterogeneity at cirrus cloud level is well documented by the evaluation of the fine particle sampling taken with the UMR sampling system. This heterogeneity can be partly explained by the interaction between aerosol and cloud elements, which is documented by the measured particle size distribution curves inside and outside of cloud elements. Assuming that particle deliquescence is caused by H₂SO₄ and/or by (NH₄)₂SO₄, particle soluble mass fractions were found to be around 30% in the first case and about 40% in the second. The most frequently occurring elements in large and coarse particles at cirrus cloud level were Si, Cl, Ba, S, Ca and C.