Forest fragmentation is considered as one of the major conservation issue. The purpose of this study is to contribute to the understanding of the national assessment of spatial patterns of forest ...fragmentation and influence of deforestation on fragmentation in the Indian forests during three decade interval (1975-2005). Mapping of forest cover was carried out based on Landsat MSS and IRS P6 AWiFS data using hybrid classification techniques on 1:250,000 scale. The present study considered biogeographic zones as a major stratum for national level assessment. The forest fragmentation was analysed based on landscape indices which allow quantification and categorisation of complex forest landscapes and depict landscape composition, structure and scenario of fragmentation. The analysis revealed that in all biogeographic zones, more than 90% of total number of forest fragments consists of patches having area less than 1km2. At national level the mean forest patch size stands at 187ha. The total core area was highest for Islands (87.4%) followed by Eastern Himalayas (82.5%), Deccan (78.9%), Deserts (76.4%) and Eastern Ghats (76%). The temporal analysis shows that the loss of Indian forest area as 5.8% during 1975–2005. The annual rate of deforestation has been computed as 0.20% at national level. The decreased mean patch size, increased edge density and increased number of patches from 1975 to 2005 indicates ongoing fragmentation in biogeographic zones. The very high fragmentation in Trans Himalayas is contributed mostly by the natural factors while in other biogeographic zones, increased fragmentation is due to deforestation.
We report results from in‐situ measurements of lattice expansion during flash sintering of 3 mol% yttria stabilized tetragonal zirconia taken at the Advanced Photon Source, Argonne National ...Laboratory. The expansion is anisotropic, with the relative expansion of the a‐lattice constant exceeding that of the c‐lattice constant. The anisotropic expansion cannot be explained by thermal expansion and is consistent with predictions from ab‐initio calculations based upon the generation of vacancy‐interstitial pairs of zirconium and oxygen.
A deadly cascade
A catastrophic landslide in Uttarakhand state in India on February 2021 damaged two hydropower plants, and more than 200 people were killed or are missing. Shugar
et al.
describe the ...cascade of events that led to this disaster. A massive rock and ice avalanche roared down a Himalayan valley, turning into a deadly debris flow upstream from the first of the two hydropower plants. The sequence of events highlights the increasing risk in the Himalayas caused by increased warming and development.
Science
, abh4455, this issue p.
300
A cascade of events starting with a massive avalanche eventually triggered a deadly debris flow in the Indian Himalaya.
On 7 February 2021, a catastrophic mass flow descended the Ronti Gad, Rishiganga, and Dhauliganga valleys in Chamoli, Uttarakhand, India, causing widespread devastation and severely damaging two hydropower projects. More than 200 people were killed or are missing. Our analysis of satellite imagery, seismic records, numerical model results, and eyewitness videos reveals that ~27 × 10
6
cubic meters of rock and glacier ice collapsed from the steep north face of Ronti Peak. The rock and ice avalanche rapidly transformed into an extraordinarily large and mobile debris flow that transported boulders greater than 20 meters in diameter and scoured the valley walls up to 220 meters above the valley floor. The intersection of the hazard cascade with downvalley infrastructure resulted in a disaster, which highlights key questions about adequate monitoring and sustainable development in the Himalaya as well as other remote, high-mountain environments.
India, a mega-diverse country, possesses a wide range of climate and vegetation types along with a varied topography. The present study has classified forest types of India based on multi-season IRS ...Resourcesat-2 Advanced Wide Field Sensor (AWiFS) data. The study has characterized 29 land use/land cover classes including 14 forest types and seven scrub types. Hybrid classification approach has been used for the classification of forest types. The classification of vegetation has been carried out based on the ecological rule bases followed by Champion and Seth’s (1968) scheme of forest types in India. The present classification scheme has been compared with the available global and national level land cover products. The natural vegetation cover was estimated to be 29.36 % of total geographical area of India. The predominant forest types of India are tropical dry deciduous and tropical moist deciduous. Of the total forest cover, tropical dry deciduous forests occupy an area of 2,17,713 km² (34.80 %) followed by 2,07,649 km² (33.19 %) under tropical moist deciduous forests, 48,295 km² (7.72 %) under tropical semi-evergreen forests and 47,192 km² (7.54 %) under tropical wet evergreen forests. The study has brought out a comprehensive vegetation cover and forest type maps based on inputs critical in defining the various categories of vegetation and forest types. This spatially explicit database will be highly useful for the studies related to changes in various forest types, carbon stocks, climate-vegetation modeling and biogeochemical cycles.
An ecosystem approach is the only way to conserve habitats and the enormous number of species. The related area-based Aichi biodiversity target of the convention on biological diversity aims to ...conserve at least 17% of terrestrial environment by 2020. This is the first regional study to recognize a network of key habitats to achieve conservation goals. It is essential to have a spatial framework by creating the indicator using existing remote sensing-based data. In this work, conservation principles were integrated at the ecosystem level covering irreplaceability and vulnerability along with representativeness. Forest persistence, ecosystem rarity, forest intactness, landscape-level ecosystem, biomass carbon stocks, and biological richness were among the biological criteria used to analyze ecosystem irreplaceability. The proxies used for ecosystem vulnerability are high fragmentation, fire hotspots and proximity to disturbance factors. A unique value is assigned to each individual pixel in the prioritization map. Overall representation of habitat coverage in protected area network of South Asian countries indicates under-representation of several forest types with less than 17% coverage. The overlay of the priority areas proposes that there is a possibility of conserving many species with the notification of protected areas. This study demonstrates the conservation priorities by identifying key habitats based on multiple conservation principles.
IRE1 couples endoplasmic reticulum unfolded protein load to RNA cleavage events that culminate in the sequence-specific splicing of the Xbp1 mRNA and in the regulated degradation of diverse ...membrane-bound mRNAs. We report on the identification of a small molecule inhibitor that attains its selectivity by forming an unusually stable Schiff base with lysine 907 in the IRE1 endonuclease domain, explained by solvent inaccessibility of the imine bond in the enzyme-inhibitor complex. The inhibitor (abbreviated 4μ8C) blocks substrate access to the active site of IRE1 and selectively inactivates both Xbp1 splicing and IRE1-mediated mRNA degradation. Surprisingly, inhibition of IRE1 endonuclease activity does not sensitize cells to the consequences of acute endoplasmic reticulum stress, but rather interferes with the expansion of secretory capacity. Thus, the chemical reactivity and sterics of a unique residue in the endonuclease active site of IRE1 can be exploited by selective inhibitors to interfere with protein secretion in pathological settings.
The focus of the study was to develop a nation-wide forest cover database of Myanmar by assessing and predicting the forest cover changes in the period of 1950 to 2027. This study estimated the net ...changes in forests at regional level along with spatial patterns of forest fragmentation using multi-source data. The results indicate forest area representing as 77.1%, 65.3%, 54.1% and 50.6% of the total geographical area of Myanmar during 1950, 1975, 2005 and 2016 respectively. This study predicted the forest cover changes in Myanmar using Module for Land use change evaluation. The five spatial variables were used to determine the relationship between deforestation and explanatory variables. The predicted forest cover of Myanmar for 2027 shows 48.4% of total geographical area under forest. The model predicted a further decrease of 14,878 km
2
of forest area in Myanmar between 2016 and 2027. The forest cover loss analysed using the classified maps of 1950 and 2016 indicated an overall loss of 34.4% of the forest cover. Ayeyarwady, Mandalay and Nayi Pyi Taw were found to be showing the highest rate of deforestation in the recent period of 2005–2016. This study has provided an insight for understanding of long-term deforestation trends of Myanmar. It offers a valuable inputs for effective management of forest resources and restoration programs as it delineates and forecast the spatial changes in forests from past to future.
ABSTRACT
We present photometric and spectroscopic observations of the unusual Type Ia supernova ASASSN-18tb, including a series of Southern African Large Telescope spectra obtained over the course of ...nearly six months and the first observations of a supernova by the Transiting Exoplanet Survey Satellite. We confirm a previous observation by Kollmeier et al. showing that ASASSN-18tb is the first relatively normal Type Ia supernova to exhibit clear broad (∼1000 km s−1) H α emission in its nebular-phase spectra. We find that this event is best explained as a sub-Chandrasekhar mass explosion producing $M_{\mathrm{ Ni}} \approx 0.3\,\, \rm {M}_\odot$. Despite the strong H α signature at late times, we find that the early rise of the supernova shows no evidence for deviations from a single-component power-law and is best fit with a moderately shallow power law of index 1.69 ± 0.04. We find that the H α luminosity remains approximately constant after its initial detection at phase +37 d, and that the H α velocity evolution does not trace that of the Fe iii λ4660 emission. These suggest that the H α emission arises from a circumstellar medium (CSM) rather than swept-up material from a non-degenerate companion. However, ASASSN-18tb is strikingly different from other known CSM-interacting Type Ia supernovae in a number of significant ways. Those objects typically show an H α luminosity two orders of magnitude higher than what is seen in ASASSN-18tb, pushing them away from the empirical light-curve relations that define ‘normal’ Type Ia supernovae. Conversely, ASASSN-18tb exhibits a fairly typical light curve and luminosity for an underluminous or transitional SN Ia, with MR ≈ −18.1 mag. Moreover, ASASSN-18tb is the only SN Ia showing H α from CSM interaction to be discovered in an early-type galaxy.
Deforestation and fragmentation are important concerns in managing and conserving tropical forests and have global significance. In the Indian context, in the last one century, the forests have ...undergone significant changes due to several policies undertaken by government as well as increased population pressure. The present study has brought out spatiotemporal changes in forest cover and variation in forest type in the state of Odisha (Orissa), India, during the last 75 years period. The mapping for the period of 1924–1935, 1975, 1985, 1995 and 2010 indicates that the forest cover accounts for 81,785.6 km
2
(52.5 %), 56,661.1 km
2
(36.4 %), 51,642.3 km
2
(33.2 %), 49,773 km
2
(32 %) and 48,669.4 km
2
(31.3 %) of the study area, respectively. The study found the net forest cover decline as 40.5 % of the total forest and mean annual rate of deforestation as 0.69 % year
−1
during 1935 to 2010. There is a decline in annual rate of deforestation during 1995 to 2010 which was estimated as 0.15 %. Forest type-wise quantitative loss of forest cover reveals large scale deforestation of dry deciduous forests. The landscape analysis shows that the number of forest patches (per 1,000) are 2.463 in 1935, 10.390 in 1975, 11.899 in 1985, 12.193 in 1995 and 15.102 in 2010, which indicates high anthropogenic pressure on the forests. The mean patch size (km
2
) of forest decreased from 33.2 in 1935 to 5.5 in 1975 and reached to 3.2 by 2010. The study demonstrated that monitoring of long term forest changes, quantitative loss of forest types and landscape metrics provides critical inputs for management of forest resources.
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