Spatial pattern of grassland aboveground biomass and its environmental controls in the Eurasian steppe

Vegetation biomass is an important component of terrestrial ecosystem carbon stocks. Grasslands are one of the most widespread biomes worldwideplaying an important role in global carbon cycling. Thereforestudying spatial patterns of biomass and their correlations to environment in grasslands is fundamental to quantifying terrestrial carbon budgets. The Eurasian steppean important part of global grasslandsis the largest and relatively well preserved grassland in the world. In this studywe analyzed the spatial pattern of aboveground biomass(AGB)and correlations of AGB to its environment in the Eurasian steppe by meta-analysis. AGB data used in this study were derived from the harvesting method and were obtained from three data sources(literatureglobal NPP database at the Oak Ridge National Laboratory Distributed Active Archive Center(ORNL)some data provided by other researchers). Our results demonstrated that:(1) as for the Eurasian steppe overallthe spatial variation in AGB exhibited significant horizontal and vertical zonality. In detailAGB showed an inverted parabola curve with the latitude and with the elevationwhile a parabola curve with the longitude. In additionthe spatial pattern of AGB had marked horizontal zonality in the Black Sea-Kazakhstan steppe subregion and the Mongolian Plateau steppe subregionwhile horizontal and vertical zonality in the Tibetan Plateau alpine steppe subregion.(2) Of the examined environmental variablesthe spatial variation of AGB was related to mean annual precipitation(MAP)mean annual temperature(MAT)mean annual solar radiation(MAR)soil Gravel contentsoil p H and soil organic content(SOC) at the depth of 0–30 cm. NeverthelessMAP dominated spatial patterns of AGB in the Eurasian steppe and its three subregions.(3) A Gaussian function was found between AGB and MAP in the Eurasian steppe overallwhich was primarily determined by unique patterns of grasslands and environment in the Tibetan Plateau. AGB was significantly positively related to MAP in the Black Sea-Kazakhstan steppe subregion(elevation 3000 m)the Mongolian Plateau steppe subregion(elevation 3000 m) and the surface(elevation ≥ 4800 m) of the Tibetan Plateau. Neverthelessthe spatial variation in AGB exhibited a Gaussian function curve with the increasing MAP in the east and southeast margins(elevation 4800 m) of the Tibetan Plateau. This study provided more knowledge of spatial patterns of AGB and their environmental controls in grasslands than previous studies only conducted in local regions like the Inner Mongolian temperate grasslandthe Tibetan Plateau alpine grasslandetc.     

Mycobiota of the disused ore mine of Marcinków in?nie?nik Masiff(western Poland)

Marcinków(Lower Silesia, ?nie?nik Masiff,south-western Poland) has been a well-known mining centre since the mid-15 th century. Mineral extraction ended in 1949 with the ores of Pb, Ag, Cu and occasionally Au, U or graphite mined there. The mine is surrounded by metamorphic graphite and mica schist. It is not open to the public and no bats have been recorded living in. The aim of this study was the mycological analysis of the air, the rock surface and the water of the disused ore mine of Marcinków.Additionally, the chemical composition of rocks and water, and microclimate conditions of the adit were determined. Fungi were identified using a combination of phenotypic and molecular methods.Six taxa of fungi were cultured from the indoor air samples of the adit, whereas the outdoor air samples contained only five taxa. On the other hand, nine taxa were isolated from both the rocky walls and the water.The Aspergillus group was present only on the rocks and in the water, whereas Cladosporium herbarum,Dumontinia tuberosa, Epicoccum nigrum, Hirsutella sp., were found exclusively in the air. The mycobiota found in the ore mine were mostly similar to those recorded in other mines and natural caves. However,it should be noted that the internal microclimate and chemical compounds of the rocks.     

山地灾害沉积物的测年综述

山地灾害事件发生的年代是理解其发育机制并作出预测的基础.在长时间尺度上,常用的测牟方法有光释光、14C、宇宙成因核素和火山灰测年等,其中的关键是能否在剖面中寻找到合适的测年物质.短时间尺度的测年方法以树轮为主,辅以地衣测年.在山地灾害中,不仅灾害沉积本身,其相关沉积物对事件年代也具有指示意义.在实际应用中,根据测年材料...     

Changes in bark properties and hydrology following prescribed fire in Pinus taeda and Quercus montana

In the eastern United States, the use of prescribed fire as a silvicultural technique to manage for desirable upland tree species is increasing in popularity. Bark physical properties such as thickness, density, and porosity have known associations with fire tolerance among species. These physical properties simultaneously influence rainfall interception and canopy storage and thus are of interest across a range of disciplines. Furthermore, while these characteristics are innate to a species, it is unknown whether repeated exposure to fire facilitates physical change in bark structure and whether these changes are consistent among species. To answer these questions, bark samples were collected from mature pine (Pinus taeda L.) and oak (Quercus montana Willd.) trees from sites across the Bankhead National Forest in Alabama, USA under three different burn regimes: 3-year cycle, 9-year cycle, and no fire. Samples were analysed in the laboratory for bulk density, porosity, water storage capacity, and hygroscopicity (the amount of atmospheric water vapour absorbed by bark during non-rainfall conditions). Drying rates of saturated samples under simulated wetting conditions were also assessed. Oak bark had higher bulk density, lower porosity, and dried slower than pine bark. Interestingly, bark from both species had lower bulk density, higher porosity, greater water storage capacity, and dried faster in stands that were burned every 3 years compared to other fire regimes (p < 0.001). In summary, this study demonstrates that prescribed fire regimes in an eastern US forest alter bark structure and thus influence individual tree control on hydrological processes. The increase in bark water storage capacity, coupled with faster bark evaporation times may lead to less water inputs to the forest floor and drier overall conditions. Further investigation of this fire-bark-water feedback loop is necessary to understand the extent of these mechanisms controlling landscape-scale conditions.     

Insights into Holocene relative sea-level changes in the southern North Sea using an improved microfauna-based transfer function

In light of global warming and rising relative sea level (RSL), detailed reconstructions of RSL histories and their controlling processes are essential in order to manage coastal-protection challenges. This study contributes to unravelling Holocene RSL change on the East Frisian North Sea coast in high resolution and with a new approach for the German Bight. For the first time, a transfer function (vertical error: 29.7 cm ? ~11% of the mean tidal range) for RSL change based on a combined training set of benthic foraminifers and ostracods from the back-barrier tidal basin of Spiekeroog is applied to the Holocene record of the back-barrier tidal basin of Norderney. The resulting RSL curve for the Norderney tidal basin is corrected for decompaction and shows a deceleration in RSL rise between 6000 and 5000 cal bp. The smallest possible error envelope (~1 m) results from the good suitability of salt-marsh layers between 5000 and 4000 cal bp. The RSL curve provides an approach towards the closure of the common data gap of peat-based curves for the southern North Sea related to a lack of basal peats in the youngest age range, and verifies regional differences in glacial isostatic adjustment.     

Hydrogeological origin of the CO2-rich mineral water of Vilajuïga in the Eastern Pyrenees (NE Catalonia,Spain)

The mineral water of Vilajuïga village in Alt Empordà (NE Catalonia, Spain) owes its uniqueness to an emanation of geogenic CO₂ that modifies groundwater hydrochemistry to produce a differentiated HCO₃–Na- and CO₂-rich groundwater among the usual Ca–HCO₃ type found in this region. A hydrogeological conceptual model attributes its occurrence to the intersection of two faults: La Valleta and Garriguella-Roses. The former provides a thrust of metamorphic over igneous rocks, formed during the Paleozoic, over a layer of ampelitic shale that, from a hydrogeological perspective, acts as a confining layer. The Garriguella-Roses normal fault, which originated during the Neogene, permits the degassing of geogenic CO₂ that is attributed to volcanic activity occurring in the Neogene. Groundwater mixing from the metamorphic and igneous rock units plus the local occurrence of CO₂ creates a HCO₃–Na water that still holds free-CO₂ in solution. Interaction with the gas phase is restricted at the intersection of the two faults. Radiocarbon dating, after correcting for geogenic dead carbon, estimates an age of 8,000 years BP. The low tritium content (0.7 TU) indicates that Vilajuïga water is a mix of “older” groundwater recharged in the metamorphic rocks of the Albera range and “younger” groundwater from the igneous rocks of the Rodes range, over a recharge area of 45 km² and a maximum elevation of 600 m. Given its origin as rare groundwater in the southern slope of the Eastern Pyrenees, purposeful monitoring is necessary to evaluate the groundwater vulnerability and anticipate impacts from nearby wells and climate-change effects.