Trophic status of Tilitso,a high altitude Himalayan lake

The trophic status and water quality of Lake Tilitso (4920 m above sea level) in a high altitude region in central Nepal were surveyed in September, 1984. The lake is rather large with a maximum depth of 95 m and a surface area of 10.2 km². The lake water was turbid due to glacier silt and the euphotic layer was only 5 m deep. The nutrient concentration was very low with total phosphorus concentration 1–6 μg l⁻¹, and DTN concentration 0.10–0.22 mg l⁻¹. The phytoplankton biomass and chlorophyll-a concentration were also low. Primary production was estimated to be about 12 mg C m⁻² d⁻¹. The concentrations of particulate matter and most cations and bacterial number were higher in the epilimnion than in the hypolimnion. The trophic status of this lake was estimated as ultraoligotrophic.     

Environmental vulnerability assessment of eco-development zone of Great Himalayan National Park,Himachal Pradesh,India

The Great Himalayan National Park (GHNP), located in western Himalaya, is a key mountainous ecosystem prone to environmental vulnerability because of anthropogenic stress and the natural disasters, viz., landslide and forest fire. We assessed the environmental vulnerability of the eco-development zone of GHNP using remote sensing (RS) and geographic information system (GIS) technologies. To quantify the environmental vulnerability, a numerical model using spatial principal component analysis (SPCA) was developed. This model considered five factors: land use/land cover, forest canopy density, forest fire risk, landslide susceptibility and human population density. The environmental vulnerability integrated index (EVSI) calculated for the 1990, 2000 and 2010 periods was found to be 2.00, 2.72, and 3.40, respectively. The results showed temporal increase in the environmental vulnerability in the zone. Based on the numerical outputs, the vulnerability of the region was categorized into five classes: potential, slight, medium, high, and severe. The primary factor responsible for the increase in vulnerability overtime was land use/land cover change in the study area due to hydro-electric power projects, construction of roads, and other infrastructure developments. Forest fire and decreased forest canopy density are other major contributing factors responsible for the increase in the environmental vulnerability. Our results indicated that integration of RS, GIS and SPCA can effectively quantify and assess environmental vulnerability.     

利用3S技术对梅里雪山地区植被制图的精度检验分析

在野外考察的基础上,应用3S技术,完成了云南西北部梅里雪山地区的1：50000的植被图．对已完成的植被图通过野外收集的GPS点进行校正,GPS样点数的多少依据统计学抽样调查的样本大小计算而得,用这些校正样点数建立混淆矩阵进行植被图精度计算,最后利用计算成数方差进行检验．混淆矩阵计算得出植被图总的判对精度即整体精度OA为84．7％,利用计算成数方差检验,结果表明大部分类型为90％以上．基于3S技术完成的植被图精度取决于区域面积大小和植被分类等级,而利用遥感技术来划分的植被等级与传统的植被分类等级不完全一致．     

Fluxes and chemistry of nitrogen oxides in the Niwot Ridge,Colorado, snowpack

The effect of snow cover on surface-atmosphere exchanges of nitrogen oxides (nitrogen oxide (NO) + nitrogen dioxide (NO₂); note, here ‘NO₂’ is used as surrogate for a series of oxidized nitrogen gases that were detected by the used monitor in this analysis mode) was investigated at the high elevation, subalpine (3,340 m asl) Soddie site, at Niwot Ridge, Colorado. Vertical (NO + NO₂) concentration gradient measurements in interstitial air in the deep (up to ~2.5 m) snowpack were conducted with an automated sampling and analysis system that allowed for continuous observations throughout the snow-covered season. These measurements revealed sustained, highly elevated (NO + NO₂) mixing ratios inside the snow. Nitrogen oxide concentrations were highest at the bottom of the snowpack, reaching levels of up to 15 ppbv during mid-winter. Decreasing mixing ratios with increasing distance from the soil–snow interface were indicative of an upwards flux of NO from the soil through the snowpack, and out of the snow into the atmosphere, and imply that biogeochemical processes in the subnival soil are the predominant NO source. Nitrogen dioxide reached maximum levels of ~3 ppbv in the upper layers of the snowpack, i.e., ~20–40 cm below the surface. This behavior suggests that a significant fraction of NO is converted to NO₂ during its diffusive transport through the snowpack. Ozone showed the opposite behavior, with rapidly declining levels below the snow surface. The mirroring of vertical profiles of ozone and the NO₂/(NO + NO₂) ratio suggest that titration of ozone by NO in the snowpack contributes to the ozone reaction in the snow and to the ozone surface deposition flux. However, this surface efflux of (NO + NO₂) can only account for a minor fraction of ozone deposition flux over snow that has been reported at other mid-latitude sites. Neither (NO + NO₂) nor ozone levels in the interstitial air showed a clear dependence on incident solar irradiance, much in contrast to observations in polar snow. Comparisons with findings from polar snow studies reveal a much different (NO + NO₂) and ozone snow chemistry in this alpine environment. Snowpack concentration gradients and diffusion theory were applied to estimate an average, wintertime (NO + NO₂) flux of 0.005–0.008 nmol m⁻² s⁻¹, which is of similar magnitude as reported (NO + NO₂) fluxes from polar snow. While fluxes are similar, there is strong evidence that processes controlling (NO + NO₂) fluxes in these environments are very different, as subnivial soil at Niwot Ridge appears to be the main source of the (NO + NO₂) efflux, whereas in polar snow (NO + NO₂) has been found to be primarily produced from photochemical de-nitrification of snow nitrate.     

Release and uptake of volatile inorganic and organic gases through the snowpack at Niwot Ridge,Colorado

Whole air drawn from four heights within the high elevation (3,340 m asl), deep, winter snowpack at Niwot Ridge, Colorado, were sampled into stainless steel canisters, and subsequently analyzed by gas chromatography for 51 volatile inorganic and organic gases. Two adjacent plots with similar snow cover were sampled, one over bare soil and a second one from within a snow-filled chamber where Tedlar/Teflon-film covered the ground and isolated it from the soil. This comparison allowed for studying effects from processes in the snowpack itself versus soil influences on the gas concentrations and fluxes within and through the snowpack. Samples were also collected from ambient air above the snow surface for comparison with the snowpack air. Analyzed gas species were found to exhibit three different kinds of behavior: (1) One group of gases, i.e., carbon dioxide (CO₂), chloroform (CHCl₃), dimethylsulfide (CH₃)₂S, carbondisulfide (CS₂), and dichlorobromomethane (CHBrCl₂), displayed higher concentrations inside the snow, indicating a formation of these species and release into the atmosphere. (2) A second group of compounds, including carbon monoxide (CO), carbonyl sulfide (COS), the hydrocarbons methane, ethane, ethyne, benzene, and the halogenated compounds methylchloride (CH₃Cl), methylbromide (CH₃Br), dibromomethane (CH₂Br₂), bromoform (CHBr₃), tetrachloromethane (CCl₄), CFC-11, CFC-12, HCFC-22, CFC-113, 1,2-dichloroethane, methylchloroform, HCFC-141b, and HCFC-142b, were found at lower concentrations in the snow, indicating that the snow and/or soil constitute a sink for these gases. (3) For 21 other gases absolute concentrations, respectively concentration gradients, were too low to unequivocally identify their uptake or release behavior. For gases listed in the first two groups, concentration gradients were incorporated into a snowpack gas diffusion model to derive preliminary estimates of fluxes at the snow-atmosphere interface. The snowpack gradient flux technique was found to offer a highly sensitive method for the study of these surface gas exchanges. Microbial activities below this deep, winter snowpack appear to be the driving mechanism behind these gas sources and sinks. Flux results were applied to a simple box model to assess the potential contribution of the snowpack uptake rates to atmospheric lifetimes of these species.     

Temperature-dependent phosphate solubilization by cold- and pH-tolerant species of Aspergillus isolated from Himalayan soil

Ten species of Aspergillus isolated from soil samples collected from different locations in the Indian Himalayan region have been studied for their growth requirements and tricalcium phosphate solubilization at different temperatures. The Aspergillus species could grow at low temperature and tolerated a wide range of pH. Phosphate solubilization by various Aspergillus species ranged between 374 μg/ml (A. candidus) to 1394 μg/ml (A. niger) at 28°C, 33 μg/ml (A. fumigatus) to 2354 μg/ml (A. niger) at 21°C, 93 μg/ml (A. fumigatus) to 1452 μg/ml (A. niger) at 14°C, and 21 μg/ml (A. wentii) to 83 μg/ml (A. niger) at 9°C. At 21 and 28°C, phosphate solubilization showed a decrease within 4 weeks of incubation, whereas at 9°C and 14°C, it continued further up to 6 weeks of incubation. In general, phosphate solubilization by different Aspergillus species was recorded at a maximum of 28°C or 21°C; biomass production was favored at 21°C or 14°C. Conversely, A. nidulans and A. sydowii exhibited maximum phosphate solubilization at 14°C and produced maximum biomass at 21°C. Data suggest that suboptimal conditions (higher or lower temperature) for fungal growth and biomass production were optimal for the production of metabolites involved in phosphate solubilization. Significant negative correlations were obtained between pH and phosphate solubilization for eight species at 28°C, for seven at 21°C, and for nine at 14°C. Extracellular phosphatase activity was exhibited only in case of A. niger, whreas intracellular phosphatase activity was detected in all species, the maximum being in A. niger. Statistically significant positive or negative correlations were obtained between phosphate solubilization and other parameters in most cases at different temperatures.     

新疆北塔山雪豹对秋季栖息地的选择

2004年9~10月,对新疆北塔山地区雪豹(Unicaunica)栖息地选择进行了调查。在选定的15条样带上测定了59个利用样方及30个任意样方的6种生境特征(海拔、地形、植被类型、生境平坦度、放牧状况和坡向),其结果如下:Vanderploeg和Scavia选择指数表明:雪豹对海拔、地形、植被类型、生境平坦度和坡向存在选择性:(1)雪豹偏好利用海拔2000~2200m,而避开2600~3000m区域;(2)倾向于悬崖底部和山嵴,避开山坡和山谷;(3)偏好于灌丛,避开森林;(4)避开平坦的开阔地;(5)倾向于选择非放牧区域活动;(6)倾向于选择北坡,避开南坡。对生境特征的主成分分析显示:前3个主成分(海拔、地形和植被类型)的累积贡献率达到75·76%,可以反映雪豹的栖息地特征,同时表明:影响雪豹栖息地选择的主要因素依次为放牧状况、植被类型、地形和生境平坦度。     

拉萨藏雪鸡春季栖息地选择

2005年3—4月,在拉萨曲水县雄色寺周围山上的灌丛地,对藏雪鸡栖息地选择,通过调查和测量与其有关的14个参数,发现雪鸡喜欢在灌丛盖度较低、距离民居近的地方觅食,并喜欢在灌丛盖度较低、草本种类较少、草本盖度较低、岩石较多、距民房距离较近的地方休息。另外还发现,人类保护和投食对雪鸡栖息地选择也有很大的影响。调查结果显示,研究地区的雪鸡活动在很大程度上依赖人类活动。     

Floristic patterns,ecological gradients and biodiversity in the composite channels (Central Alps,Italy)

Composite channels in the alpine region are heterogeneous environments resulting from a variety of erosive and depositional processes. They can have different ecological functions: habitats for plant species, conduits, filters, sources and sinks. They can contain sparse, intermittent vegetation cover, and are frequently free of vegetation except along the banks and levees. We hypothesised that this disturbed and fragmented landscape unit encourages biodiversity with characteristic plant species adapted to survive in the channel niches.     

Population genetics of Himalayan balsam (Impatiens glandulifera): comparison of native and introduced populations

Background: Invasive species can interfere in the structure and functioning of ecosystems. Better understanding of the evolution of such species will be useful when planning their management and eradication.

Aims: We aimed to compare patterns of genetic variability in Impatiens glandulifera in native and introduced regions.

Methods: We used native samples from India and Pakistan, and non-native samples from Canada, Finland and the UK. Genetic analyses included genotyping using 10 microsatellite markers and sequencing of the nuclear ITS region.

Results: Mean allele numbers from native and introduced samples were even, 8.8 and 8.5, respectively, while expected heterozygosities were higher in native samples (mean 0.738) than in non-native samples (mean 0.477). Hardy–Weinberg equilibrium testing indicated significant heterozygote deficiencies at 70% of the loci. Inbreeding coefficients were high in both native and introduced regions (range 0.201–0.726). STRUCTURE analyses showed that native samples from India and Pakistan possessed similar clustering patterns while non-native samples from the UK and Canada resembled each other. One of the four Finnish populations had a similar pattern with the UK and Canadian populations, while the rest showed similarly unique genetic compositions. ITS sequencing indicated in Pakistani samples two polymorphic sites not found in Indian samples but present in some samples from Canada, Finland and the UK.

Conclusions: Distinct population genetic patterns indicate that human-mediated dispersal is important in I. glandulifera.