Temporal variations in carbon stock of Pinus roxburghii Sargent forests of Himachal Pradesh,India

The present study was conducted in Solan Forest Division of Himachal Pradesh covering an area of about 57,158 ha. The aim was to estimate and assess the temporal change in carbon stock of the Chil Working Circle, in two forest ranges of the Division, Solan and Dharampur, over the period of 1956-2011. The inventory data of the working plans of Solan Forest Division from 1956-1957, 1984-1985 and 2002- 2003 were used in the present study while field data for biomass estimation was collected for the year 2011. The results showed a declining trend in carbon stock over 1956-1984 period, however, an increasing trend over 1984-2002 was observed, which showed a further increase for the period 2002-2011. These fluctuating trends in the forest carbon stock can be related to increasing anthropogenic pressure on forests and the subsequent introduction of a ban on green felling envisaging efficient forest management, both of which affect the forest carbon pool significantly.     

Time variant analysis of geomagnetic signals describes the volcanic activity of Mt. Etna between early 2000 and late 2002

Volcanomagnetic anomalies have been mostly observed during strong eruptions. Our aim is to improve the geomagnetic data analysis to evidence the anomalies occurring in a larger time span, especially in the phases preceding the eruptive events. We developed a time variant statistical approach and applied it to the 2000–2002 Etna geomagnetic temporal series. It is based on an algorithm that statistically predicts the geomagnetic field at the station on the volcanic edifice by that recorded at the remote one. In such a way a number of significant changes in the time series (called statistical innovations), marking the local magnetic field change, were detected. The distribution of such statistical innovations accurately describes the Etna volcanic evolution: we note a progressive increase of the innovation occurrence as the eruptive cycles were approaching and only few and weak innovations at times between the various eruptive cycles. The significance of this analysis is further confirmed by the close agreement among the mean square prediction error, strain release and the volcanic activity behavior. On the contrary, the geomagnetic field at a single station or its difference at two stations do not have any clear correlation with other measured physical quantities. The complex pattern of the prediction error was also investigated by a multifractal analysis. We found that the Holder regularity increases with the intensification of the volcanic activity, implying that innovations tend to be less sporadic and correlated during the major volcanic phases.     

Measuring daytime CO2 fluxes from the inter-tidal mangrove soils of Indian Sundarbans

The aim of this research was to measure the rate of carbon dioxide (CO₂) exchange between the soil and atmosphere in the inter-tidal forest floor of the Indian Sundarbans mangrove ecosystem and to study its response with soil temperature and soil water content. Soil CO₂ effluxes were monitored every month at two stations (between April, 2011 and March, 2012); one situated at the land–ocean boundary of the Bay of Bengal (outer part of the mangrove forest) and the other lying 55 km inshore from the coast line (inner part of the mangrove forest). The static closed chamber technique was implemented at three inter-tidal positions (landward, seaward and bare mudflats) in each station. Fluxes were measured in the daytime every half an hour by circulating chamber headspace air through a sampling manifold assembly and a closed-path non-dispersive infrared gas analyser. The fluxes ranged between 0.15 and 2.34 μmol m^?2 s^?1 during the annual course of sampling. Effluxes of higher magnitude were measured during summer; however, it abruptly decreased during the monsoon. CO₂ flux from the forest floor was strongly related to soil temperature, with the highest correlation found with temperature at 2 cm depth. No such significant relationship between soil water content and CO₂ efflux could be properly ascertained; however, excessively high soil water content was found to be the only reason which hampered the rate of effluxes during the monsoon. On the whole, landward (LW) sites of the mangrove forest emitted more than the seaward (SW) sites. Q ₁₀ values (obtained from simple exponential model) which denote the multiplicative factor by which the efflux rate increases for a 10 °C rise in temperature ranged between 2.07 and 4.05.     

Palynology and sedimentology of the Miocene series in the north-east of Tunisia: the climatic and eustatic signature

The Saouaf syncline is located in Tunisia Centre north-east, south-east of the Tunisian dorsal. The sedimentary series, starting with limestone and marlstone, is essentially an alternation of three terms, sandstone, clay and lignite. It is in this basin that the Saouaf Formation was defined as a siliciclastic and lignite series dating back to the Serravallian-Tortonian age. The pollen associations identified in this series allowed for the organization of the vegetation in the era in altitudinal levels (coastal environment, rivers edges, plains, high zones). The evolution of vertical micro-floristic associations through the detailed analysis of the palynological diagram reflects the fluctuation of climatic and ecological parameters during this period. Moreover, the facies associations reflect an evolutionary curve in the depositional environment, showing its fluctuation over time. Accordingly, the synthesis of palynological data, correlated with lithosedimentological ones, suggests the type of environment prevailing at that time. This is a coast-lagoon fluvio-deltaic environment with a significant detrital influence in a subsiding context controlled by a fluctuating but generally warm climate.     

Characterizing air–sea CO2 exchange dynamics during winter in the coastal water off the Hugli-Matla estuarine system in the northern Bay of Bengal, India

The distribution of the fugacity of CO₂ ( $ f_{{{\text{CO}}_{ 2} }} $ ) and air–sea CO₂ exchange were comprehensively investigated in the outer estuary to offshore shallow water region (lying adjacent to the Sundarban mangrove forest) covering an area of ~2,000 km² in the northern Bay of Bengal during the winter. A total of ten sampling surveys were conducted between 1 December, 2011 and 21 February, 2012. Physico-chemical variables like sea surface temperature (SST), salinity, pH, total alkalinity (TAlk), dissolved inorganic carbon (DIC) and in vivo chlorophyll-a along with atmospheric variables were measured in order to study their role in controlling the CO₂ flux. Surface water $ f_{{{\text{CO}}_{ 2} }} $ ranged between 111 and 459 μatm which correlated significantly with the SST (r = 0.71, p < 0.001, n = 62). Neither DIC nor TAlk showed any linear relationship with varying salinity in the estuarine mixing zone, demonstrating the significant presence of non-carbonate alkalinity. An overall net biological control on the surface $ f_{{{\text{CO}}_{ 2} }} $ distribution was established during the study, although no significant correlation was found between chlorophyll-a and $ f_{{{\text{CO}}_{ 2} }} $ (water). The shallow water region studied was mostly under-saturated with CO₂ and acted as a sink for atmospheric CO₂. The difference between surface water and atmospheric $ f_{{{\text{CO}}_{ 2} }} $ ( $ \Updelta f_{{{\text{CO}}_{ 2} }} $ ) ranged from ?274 to 69 μatm, with an average seaward flux of ?10.5 ± 12.6 μmol m^?2 h^?1. The $ \Updelta f_{{{\text{CO}}_{ 2} }} $ and hence the air–sea CO₂ exchange was primarily regulated by the variation in sea surface $ f_{{{\text{CO}}_{ 2} }} $ , since atmospheric $ f_{{{\text{CO}}_{ 2} }} $ varied over a comparatively narrow range of 361.23–399.05 μatm.     

Some Kaluza-Klein cosmological models in f(R,T) gravity theory

Algorithms are derived for constructing five dimensional Kaluza-Klein cosmological space-times in the presence of a perfect fluid source in the framework of f(R,T) gravity theory proposed by Harko et al. (Phys. Rev. D 84:024020, 2011). Starting from the solution of Reddy et al. (Int. J. Theor. Phys 51:3222-3227, 2012b) some classes of new solutions are generated which correspond to accelerating models of the Universe. The physical and kinematical behaviors of the models are studied.     

Seismic vertical uplift capacity of horizontal strip anchors using pseudo-dynamic approach

This paper presents the pseudo-dynamic analysis to determine the seismic vertical uplift capacity of a horizontal strip anchor using upper bound limit analysis. However, in the literature, the pseudo-static approach was used by few researchers to compute the seismic vertical pullout resistance, where the real dynamic nature of earthquake accelerations cannot be considered. Under the seismic conditions, the values of the unit weight component of uplift factor f_γE are determined for different magnitudes of soil friction angle, soil amplification, embedment ratio and seismic acceleration coefficients both in the horizontal and vertical directions. It is observed that the uplift factor f_γE decreases significantly with the increase in seismic accelerations and amplification but increases with the increase in embedment ratio. The results are compared with the existing values in the literature and the significance of the present methodology for designing the horizontal strip anchor is discussed. In presence of vertical earthquake acceleration and amplification of vibration, the present values of f_γE compare reasonably well with the existing pseudo-static values obtained by modifying the horizontal acceleration coefficient.     

Conservation And Conflicts In The Sundarban Biosphere Reserve,India

The Sundarban Biosphere Reserve in West Bengal, India, is part of the largest mangrove forest ecosystem in the world. The reserve is a world heritage site and the last refuge for the endangered Bengal tiger at a crucial time when global climate change threatens their existence. The mangrove ecosystem and wildlife conservation have become the priority for the state government of West Bengal. However, in becoming so, the state government imposes restrictions on catching fish in the core and buffer areas of the biosphere reserve, which intensify fishermen's everyday resource‐access struggles in the mangrove forest. This paper examines the conflict between local fishermen and conservation needs, broadening the understanding of human‐environment relationships in the Sundarbans region of India.