Characteristic on the Stability of Haloxylon Ammodendron Plantation in the Southern Fringe of Gurbantunggut Desert, Northwest China

Using chronosequence theory and method, the characteristics of vegetation-soil coupling and structure stability of Haloxylon ammodendron plantations in the southern fringe of Gurbantunggut Desert were analyzed. The results showed, the canopy storey of H. ammodendron plantation experienced three stages, rapid growth (the age of 7 to 20), then slow growth (the age of 20 to 28) and last decline (over the age of 28). The best natural regeneration started from 17-yr-old plantation. Vegetation-soil system coupling degree (C) and coupling coordinative degree (D) of plantations with different age were not one-to-one correspondence. The system of H. ammodendron plantations always stayed in disorder recession, vegetation and soil were prone to loss type during the process of sand-fixation. Five principal components evaluated that the first rank was 42-yr-old plantation. It was inferred that the trend of the vegetation and soil system was from senescence to harmonious development. So the trend of coordinated development between vegetation and soil would be promoted, if the artificial tending and management measures strengthened.

Modelling the productivity of Siberian larch forests from Landsat NDVI time series in fragmented forest stands of the Mongolian forest-steppe

The monitoring of the spatial and temporal dynamics of vegetation productivity is important in the context of carbon sequestration by terrestrial ecosystems from the atmosphere. The accessibility of the full archive of medium-resolution earth observation data for multiple decades dramatically improved the potential of remote sensing to support global climate change and terrestrial carbon cycle studies. We investigated a dense time series of multi-sensor Landsat Normalized Difference Vegetation Index (NDVI) data at the southern fringe of the boreal forests in the Mongolian forest-steppe with regard to the ability to capture the annual variability in radial stemwood increment and thus forest productivity. Forest productivity was assessed from dendrochronological series of Siberian larch (Larix sibirica) from 15 plots in forest patches of different ages and stand sizes. The results revealed a strong correlation between the maximum growing season NDVI of forest sites and tree ring width over an observation period of 20 years. This relationship was independent of the forest stand size and of the landscape’s forest-to-grassland ratio. We conclude from the consistent findings of our case study that the maximum growing season NDVI can be used for retrospective modelling of forest productivity over larger areas. The usefulness of grassland NDVI as a proxy for forest NDVI to monitor forest productivity in semi-arid areas could only partially be confirmed. Spatial and temporal inconsistencies between forest and grassland NDVI are a consequence of different physiological and ecological vegetation properties. Due to coarse spatial resolution of available satellite data, previous studies were not able to account for small-scaled land-cover patches like fragmented forest in the forest-steppe. Landsat satellite-time series were able to separate those effects and thus may contribute to a better understanding of the impact of global climate change on natural ecosystems.

Reconstructing LGM paleoglaciers and their ELAs along the southern fringe of the Eastern European Alps

<p>The reconstruction of paleoglaciers and specifically the calculation of their equilibrium line altitude (ELA) is an important source of quantitative paleoclimatic information in mountainous regions. During the Last Glacial Maximum (LGM), the prealpine massifs in the south-eastern part of the Alpine chain (Venetian Prealps, Carnic Prealps and Julian Prealps) hosted several small valley glaciers and local ice caps that were isolated from the larger ice-streams occupying the major valleys. Because of their small size and independent dynamics these glaciers can be considered as excellent indicators of local climatic conditions. Although this potential has long been recognised and the sediments and landforms related to these glaciations have been mapped in a few areas, a regional perspective on this type of glaciation is still lacking. This is primarily due to the wide range of methods of ELA reconstructions that has been applied historically, which makes a solid comparison between different localities difficult.</p><p>Here, we present a detailed re-evaluation of local LGM glaciation in the south-eastern Alps based on a large-scale survey of remote sensing data and targeted field work at selected localities. Recently developed GIS tools were applied for the reconstruction of paleoglacier geometries and ELAs (Pellitero et al. 2015, 2016). The obtained values are used both to discuss regional climatic patterns during the LGM and site-specific topographic factors. A specific focus is set on the Monte Cavallo group, where glacial sediments from the LGM are covering a thick sequence of interstadial lacustrine deposits. A set of new radiocarbon dates from this succession provides a first chronological control on the onset of glacier expansion in this part of the Alpine chain.</p><p> </p><p>References:</p><p>Pellitero, R. et al. 2015. A GIS tool for automatic calculation of glacier equilibrium-line altitudes. Computers & Geosciences 82: 55-62.</p><p>Pellitero, R. et al. 2016. GlaRe, a GIS tool to reconstruct the 3D surface of palaeoglaciers. Computers & Geosciences 94: 77-85.</p>

Implication of mantle dynamics beneath North-East India through the perspective of SKKS splitting analysis

<p>SKKS phase being an unique one among other core refracted phases like PKS, SKS etc. is capable of imaging the anisotropic contribution from lower mantle as per its raypath is considered. Its unique property of reflection at the core-mantle boundary enables it to carry forward the lower mantle contribution in case of seismic anisotropy is concerned. The lower mantle as a whole is assumed to be isotropic except the lowermost 200-300km (D’’ layer) which pertain a distinct diversity in the raypath of SKKS phases beyond 130<sup>o</sup> epicentral distance and thereby manifest the possible influence of lower mantle in the deformation pattern of any region. The present study of SKKS splitting analysis comprising an epicentral range of 140<sup>o</sup>-180<sup>o</sup> is primarily intended to complement the existing shear wave splitting dataset associated with north east India as well as to understand the effect of lower mantle on the splitting parameters (fast polarization direction (FPD, ϕ) and delay time (δt)). The motive of the study can be further extended to decipher the implication of such narrow epicentral range on splitting analysis. The analysis suggests that, beneath sub-Himalaya, the Indo-Eurasia collision derived lithospheric force along major thrust faults is the prime source behind the deformation, while Assam foredeep is somewhat influenced by the seismogenic Kopili Fault. There exist a striking difference in anisotropic directions between northern and southern fringe of Shillong plateau where deformations are governed by the absolute plate motion (APM) of Indian plate driven asthenospheric flow and seismically active Dauki and Dapsi faults respectively. Such disparity in splitting attributes can be inferred as the interplay of constricted back-azimuthal distribution and lean range of epicentral distance of seismic events, though the probability of lower mantle involvement cannot be ignored completely.</p>

Assessment And Detection Of Land Cover Changes In The Southern Fringe Of Kolkata Using Remotely Sensed Data

Continual, historical, and precise information about the land use and land cover (LULC) changes of the Earth’s surface is extremely important for any kind of sustainable development program, in which LULC serves as one of the major input criteria. In this study, a supervised classification was applied to five types of Landsat images collected over time (1980, 1990, 2000, 2010 and 2015) that provided recent and historical LULC conditions for the area. Four LULC categories were identified and mapped. Post-classification comparisons of the classified images indicated that the major change consisted of barren land changing into agricultural land. This analysis revealed that substantial growth of built-up areas in the south eastern part of Kolkata over the study period resulted in significant decrease in the area of water bodies, cultivated land, vegetation and wetlands. Urban land transformation has been largely driven by large number of population and high population growth rate with rapid economic and infrastructural development like the extension of metro railway, flyovers and hence huge real estate development.

Simultaneous Dual-Doppler and Mobile Mesonet Observations of Streamwise Vorticity Currents in Three Supercells

Recent high-resolution numerical simulations of supercells have identified a feature referred to as the streamwise vorticity current (SVC). Some have presumed the SVC to play a role in tornadogenesis and maintenance, though observations of such a feature have been limited. To this end, 125-m dual-Doppler wind syntheses and mobile mesonet observations are used to examine three observed supercells for evidence of an SVC. Two of the three supercells are found to contain a feature similar to an SVC, while the other supercell contains an antistreamwise vorticity ribbon on the southern fringe of the forward flank. A closer examination of the two supercells with SVCs reveals that the SVCs are located on the cool side of boundaries within the forward flank that separate colder, more turbulent flow from warmer, more laminar flow, similar to numerical simulations. Furthermore, the observed SVCs are similar to those in simulations in that they appear to be associated with baroclinic vorticity generation and have similar appearances in vertical cross sections. Aside from some apparent differences in the location of the maximum streamwise vorticity between simulated and observed SVCs, the SVCs seen in numerical simulations are indeed similar to reality. The SVC, however, may not be essential for tornadogenesis, at least for weak tornadoes, because the supercell that did not have a well-defined SVC produced at least one brief, weak tornado during the analysis period.

Deltaic Expansions of the Mahanadi Tri-delta and the Chilika Lagoon: Geospatial Approach

Prelude: The major river deltas are sinking, shrinking which accommodate ≈40% of global population. The Mahanadi tri-delta along the east coast of India consists of three river deltas i.e. the Mahanadi, the Bramhani and the Baitarani. The tri-delta encompasses many ecological hubs and the 2nd largest lagoon of Asia, the Chilika Lagoon lies in the southern corner of the delta. Presently the Mahanadi tri-delta and its coastal environments are under threat due to coastal vulnerability, population growth, urbanization and industrialization but the expansion of the delta towards south is observed. Scope: Present research is ubiquitous to know the quantity of sinking, shrinking and subsidence of the Mahanadi tri-delta under congregation of different geological setting, damming, LULC changes, soil erosion, regional sea level rise, and anthropogenic pressure. Also geospatial geomorphic changes in the anastomosis of the rivers and drainage channels are studied along with expansion of the delta to its southern fringe Methodology: The causes of vulnerability of the delta are estimated from sediment inflow and marine transgression is evaluated. The land use and land cover changes has been evaluated and analyzed by using satellite imageries, remote sensing, GIS tools and ERDAS softwares. Results: The study revealed that due to effect of relative sea-level rise, paucity of sediment influx @ 66.7% to the delta are the main causes for the delta vulnerability accompanied by geo-mining and urbanization. The extention of delta to the south is due to emergence of the Makara river system which carries more flood flow than the existing Daya river. Prominent changes in LU & LC are observed from the satellite imageries of two different period. Changes in the LU &LC of the tri-delta has shown the extension of the Mahanadi tri-delta towards south and shifting of deltaic boundary from 20 m to 50 m contour line in l landward direction during last four to five decades (recasted).