怒江云南段高山峡谷区泥石流堵河危险研究

正怒江流域云南段山高谷深,地质条件复杂,泥石流多发频发,常形成堵河事件,严重威胁区内人民生命财产安全。针对怒江云南段泥石流堵河现象,通过理论分析、数值模拟及野外验证,探讨怒江泥石流堵河类型及泥石流堵河危险性评价。怒江云南段泥石流堵河以部分堵塞类型为主,泥石流主沟两侧为高危险区,建议重点防护或安全避让。     

Modelling evapotranspiration in an alpine grassland ecosystem on Qinghai‐Tibetan plateau

Thus far, measurements and estimations of actual evapotranspiration (ET) from high‐altitude grassland ecosystems in remote areas like the Qinghai‐Tibetan plateau are still insufficient. To address these issues, a comparison between the results of the eddy covariance (EC) measurements and the estimates, considering the Katerji and Perrier (KP), the Todorovic (TD) and the Priestley–Taylor (PT) models, was carried out over an alpine grassland (38^o03'1.7'' N, 100^o 27’ 26'' E; 3032 m a.s.l.) during the growing seasons in 2008 and 2009. The results indicated that the KP model after a particularly simple calibration gave the most effective ET values in different time scales, the PT model slightly underestimate ET at night and the TD model significantly overestimated ET at noon. In addition, the canopy resistance calculated by the TD model was completely different from that calculated using the inverted EC‐measured data and the KP model, which may be due to some unrealistic assumptions made by the TD model. The KP parameters were a = 0.17 and b = 1.50 for the alpine grassland and appeared to be interannually stable. However, the PT parameter showed some interannual variations (α = 0.83 and 0.74 for 2008 and 2009, respectively). Therefore, the KP model was preferred to estimate the actual ET at both hourly and daily time scales. The PT model, being the simplest approach and field condition dependent, was recommended when available weather data were rare. On the contrary, the TD model always overestimated the actual ET and should be avoided in case of the alpine grassland ecosystems. Copyright © 2012 John Wiley & Sons, Ltd.     

A field,laboratory, and literature review evaluation of the water retention curve of volcanic ash soils: How well do standard laboratory methods reflect field conditions?

Accurate determination of the water retention curve (WRC) of a soil is essential for the understanding and modelling of the subsurface hydrological, ecological, and biogeochemical processes. Volcanic ash soils with andic properties (Andosols) are recognized as important providers of ecological and hydrological services in mountainous regions worldwide due to their large fraction of small size particles (clay, silt, and organic matter) that gives them an outstanding water holding capacity. Previous comparative analyses of in situ (field) and standard laboratory methods for the determination of the WRC of Andosols showed contrasting results. Based on an extensive analysis of laboratory, experimental, and field measured WRCs of Andosols in combination with data extracted from the published literature we show that standard laboratory methods using small soil sample volumes (≤300 cm³) mimic the WRC of these soils only partially. The results obtained by the latter resemble only a small portion of the wet range of the Andosols' WRC (from saturation up to −5 kPa, or pF 1.7), but overestimate substantially their water content for higher matric potentials. This discrepancy occurs irrespective of site-specific land use and cover, soil properties, and applied method. The disagreement limits our capacity to infer correctly subsurface hydrological behaviour, as illustrated through the analysis of long-term soil moisture and matric potential data from an experimental site in the tropical Andes. These findings imply that results reported in past research should be used with caution and that future research should focus on determining laboratory methods that allow obtaining a correct characterization of the WRC of Andosols. For the latter, a set of recommendations and future directions to solve the identified methodological issues is proposed.     

THE DENDROCLIMATOLOGICAL POTENTIAL OF AN ALPINE SHRUB,CASSIOPE MERTENSIANA,FROM MOUNT RAINIER,WA, USA

The application of dendrochronological techniques to shrubs found in arctic and alpine plant communities is opening previously untapped regions to the exploration of plant‐climate ecological relationships and climate reconstruction. In this pilot study, we present growth (1963–2004), reproduction (1963–2004), and stable carbon isotope ratio (1975–2004) chronologies for Cassiope mertensiana from a subalpine site in Mount Rainier National Park, Washington, USA. Based on simple linear correlation analysis, positive correlations characterize plant growth and previous year mean maximum temperature in April and June, suggesting the influence of temperature on snowpack and, in turn, on growing season length, plant and soil insulation, and nutrient and moisture availability. Plant growth and reproduction are significantly correlated with current year July mean maximum temperature and total precipitation, indicating the importance of a warm and extended growing season for optimal plant development. Using step‐wise multiple linear regression analysis, we developed a preliminary calibration model for July mean maximum temperature (R = 0.63), extending over the 1974–2004 time period. This archive has the potential to elucidate multi‐scale, spatially‐explicit, ecological and climatic information for alpine ecosystems situated along a north‐south transect from the southern Yukon to the Pacific Northwest of the United States.     

遥感GPP模型在高寒草甸的应用比较

随着遥感数据时空分辨率的提高,大范围实时监测总初级生产力GPP(Gross Primary Productivity)的变化成为可能。本研究收集了黑河流域阿柔冻融观测站的气象观测资料和MODIS数据,驱动VPM、TG、VI和EC-LUE4个模型估算了该站点的GPP,并应用涡动相关观测的GPP验证了模拟结果,并比较了这4个模型的模拟精度。结果表明:阿柔站2009年的涡动相关观测的GPP、NEE(Net Ecosystem Exchange)和ER(Ecosystem Respiration)分别为:804.2gC/m2/yr、129.6gC/m2/yr和673.6gC/m2/yr。该站点光合作用固定的碳有83.8%通过生态系统的呼吸作用释放到大气中。基于遥感的GPP模型能够很好地模拟高寒草甸的GPP,全年的判定系数在0.94以上,生长季的判定系数大于0.84。     

The use of egg shells to infer the historical presence of copepods in alpine lakes

Copepods (Class Crustacea, Order Copepoda) are rarely included in paleoecological studies of lakes because they lack long-lasting exoskeletal remains. We describe the remains of eggs (egg shells) from Hesperodiaptomus copepods that are well preserved and abundant in alpine lake sediments. We demonstrate that the egg shells are the remains of Hesperodiaptomus eggs based on (i) the similar size and morphology of egg shells collected from sediments and those produced from the hatching of eggs obtained from laboratory-maintained Hesperodiaptomus, and (ii) the finding that diapausing eggs collected from lake sediments and hatched in the laboratory produced copepod nauplii that were morphologically indistinguishable from those hatched from eggs produced by laboratory-maintained Hesperodiaptomus. Egg shells were approximately two orders of magnitude more abundant in sediment cores than were viable diapausing eggs, making egg shells superior to viable diapausing eggs for quantifying the historical presence and abundance of Hesperodiaptomus. These results have important implications for alpine lake restoration as egg shells can be used to identify lakes in which Hesperodiaptomus was eliminated by fish introductions but has failed to return after fish eradication, lakes in which the pre-disturbance conditions are likely to be restored only by reintroductions of this important taxon.     

Chemical denudation rates in Kärkevagge, Swedish Lapland

This study examines the spatial and temporal variability of chemical denudation rates in Kärkevagge, northern Sweden. The chemical flux rates within the valley are strongly influenced by the local geology. Chemical denudation rates determined for the study period are more than double those previously reported in the literature for this valley. Rates of greater than 46t km⁻² a⁻¹ were measured at the valley mouth over the course of the melt season. This difference is likely due to differences in measurement technique compared to that used by past researchers. This rate is also much higher than for other arctic and alpine watersheds. Chemical denudation in Kärkevagge is comparable to larger temperate rivers. The rapid chemical denudation in Kärkevagge is likely due to sulfide weathering creating acid solutions.     

Geo–ecology and management of sensitive montane landscapes

Montane (alpine) areas are generally of high value for nature conservation. Such environments and the habitats they support are dynamic and often fragile. They are vulnerable to disturbance from a range of human activities and are responsive to climate changes over short and long timescales. Biodiversity and conservation values are closely linked to geological history, geomorphological processes and soils, and it is crucial that management systems are based on understanding these links.
There are many similarities between the Cairngorm Mountains (Scotland), the Giant Mountains (Czech Republic) and Abisko Mountains (Sweden) in terms of geology, geomorphology, ecology, links with biodiversity and high conservation importance. Comparable pressures and management issues involve, to varying degrees, a history of human use and impacts from deforestation, pasturing, grazing, recreation and atmospheric pollution. Landscape change therefore involves a complex interplay between natural and anthropogenic factors. Managing such change requires better understanding of the geo–ecological processes involved and the factors that determine landscape sensitivity. This is illustrated through a simple framework and examples from the three areas. Comparison of landscape sensitivity between similar montane areas, but in different geographic locations and climatic environments, should allow more informed management planning and a precautionary approach in advance of further changes in human activity and from predicted global warming scenarios.