Regeneration and tree species diversity of Sitakund Botanical Garden and Eco-park,Chittagong, Bangladesh

Anthropogenic disturbances influence plant regeneration and species diversity, which impact the conservation status of protected areas. A study was conducted in the Sitakund Botanical Garden and Eco-park （SBGE）, Chittagong, Bangladesh to analyze the natural regeneration and tree species diversity in disturbed and less disturbed zones. Stratified and systematic random sampling was used to select 50 sample plots from each of the two zones. A total number of 109 plant species from 43 families were recorded in the study; of which 93 species were of natural origin while the rest were planted. From the species with natural origin 66 were tree species, 9 were shrub species and 28 were climbers. Species richness, density of regeneration and disturbance index in the height classes （0- 0.5 m） and {dbh 〉 6 cm） indicated significant differences between the zones. The study analyzed how disturbances affect species diversity in the area. It was found that species richness and basal area are negatively related with disturbances. Moreover, density （N/ha） of trees was more likely to decrease with increasing tree height that reflects the huge demand of local people to harvest large trees as part of their income generating activities. The study findings have implications for future managementdecisions of the SGBE. To restore these ecosystems, management should focus on both biodiversity eonservation and providing benefits to local people without hampering forest ecosystems.     

An enhanced strategy for GNSS data processing of massive networks

Although the computational burden of global navigation satellite systems (GNSS) data processing is nowadays already a big challenge, especially for huge networks, integrated processing of denser networks with data of multi-GNSS and multi-frequency is desired in the expectation of more accurate and reliable products. Based on the concept of carrier range, in this study, the precise point positioning with integer ambiguity resolution is engaged to obtain the integer ambiguities for converting carrier phases to carrier ranges. With such carrier ranges and pseudo-ranges, rigorous integrated processing is realized computational efficiently for the orbit and clock estimation using massive networks. The strategy is validated in terms of computational efficiency and product quality using data of the IGS network with about 460 stations. The experimental validation shows that the computation time of the new strategy increases gradually with the number of stations. It takes about 14 min for precise orbit and clock determination with 460 stations, while the current strategy needs about 82 min. The overlapping orbit RMS is reduced from 27.6 mm with 100 stations to 24.8 mm using the proposed strategy, and the RMS could be further reduced to 23.2 mm by including all 460 stations. Therefore, the new strategy could be applied to massive networks of multi-GNSS and multi-frequency receivers and possibly to achieve GNSS data products of higher quality.     

New VLBI2010 scheduling strategies and implications on the terrestrial reference frames

In connection with the work for the next generation VLBI2010 Global Observing System (VGOS) of the International VLBI Service for Geodesy and Astrometry, a new scheduling package (Vie_Sched) has been developed at the Vienna University of Technology as a part of the Vienna VLBI Software. In addition to the classical station-based approach it is equipped with a new scheduling strategy based on the radio sources to be observed. We introduce different configurations of source-based scheduling options and investigate the implications on present and future VLBI2010 geodetic schedules. By comparison to existing VLBI schedules of the continuous campaign CONT11, we find that the source-based approach with two sources has a performance similar to the station-based approach in terms of number of observations, sky coverage, and geodetic parameters. For an artificial 16 station VLBI2010 network, the source-based approach with four sources provides an improved distribution of source observations on the celestial sphere. Monte Carlo simulations yield slightly better repeatabilities of station coordinates with the source-based approach with two sources or four sources than the classical strategy. The new VLBI scheduling software with its alternative scheduling strategy offers a promising option with respect to applications of the VGOS.     

On the breakdown of the westerlies

The dynamics of the ultra‐long Rossby waves are studied with the aid of a primitive equation numerical model. The investigation is focused on a study of the breakdown of a high‐index circulation. Different idealized flow patterns are used as initial conditions and forecasts are made with the numerical model. The influences of oceans and mountains are studied by incorporating them into the model. The results indicate that barotropic and baroclinic instabilities as well as the structure of the earth's surface are of importance for the development, but the experiments do not clearly indicate which one of these factors is most important.     

Future mitigation commitments: differentiating among non-Annex I countries

Abstract

In the long term, any definition of adequacy consistent with UNFCCC Article 2 will require increased mitigation efforts from almost all countries. Therefore, an expansion of emission limitation commitments will form a central element of any future architecture of the climate regime. This expansion has two elements: deepening of quantitative commitments for Annex B countries and the adoption of commitments for those countries outside of the current limitation regime. This article seeks to provide a more analytical basis for further differentiation among non-Annex I countries. To be both fair and reflective of national circumstances, it is based on the criteria of responsibility, capability and potential to mitigate. Altogether, non-Annex I countries were differentiated in four groups, each including countries with similar national circumstances: newly industrialized countries (NICs), rapidly industrializing countries (RIDCs), ‘other developing countries’, and least developed countries (LDCs). Based on the same criteria that were used for differentiating among non-Annex I countries, a set of decision rules was developed to assign mitigation and financial transfer commitments to each group of countries (including Annex I countries). Applying these decision rules results in (strict) reduction commitments for Annex I countries, but also implies quantifiable mitigation obligations for NICs and RIDCs, assisted by financial transfers from the North. Other developing countries are obliged to take qualitative commitments, but quantifiable mitigation commitments for these countries and the LDC group would be not justifiable. As national circumstances in countries evolve over time, the composition of the groups will change according to agreed triggers.     

Equitable access to sustainable development: operationalizing key criteria

Equitable access to sustainable development (EASD) is crucial for the future of the climate regime as it applies to adaptation, mitigation, and the means of implementation. An approach to allocating effort and deriving carbon budgets is presented here based on the United Nations Framework Convention on Climate Change (UNFCCC) principles of responsibility, capability, and sustainable development. A transparent model to operationalize EASD is applied by applying quantitative proxies for these criteria, and results for selected countries and groups are presented. A robust result is that the mitigation burden calculated by the model is significantly greater for developed than developing countries. For individual countries the results vary depending on the parameters chosen. A middle value of the mitigation burden for South Africa of 15 GtCO₂e over the first half of the 21st century is reported, with the greatest effort required when a starting year of 1970 is chosen and historical land-use, land-use change and forestry (LULUCF) emissions are excluded when accounting for responsibility. In a regime applicable to all, it is clear that although all countries must do more, some must do more than others.

Policy relevance

Equitable access to sustainable development is crucial to the climate negotiations. Quantified allocations are presented for South Africa and other countries, based on the UNFCCC principles of responsibility, capability, and sustainable development. It is shown that the mitigation burden given these principles must be significantly greater for developed than developing countries. The results are relevant to, inter alia, the upcoming 2013–2015 review and the negotiations under the Durban Platform.     

High-Latitude Springtime Photochemistry. Part I: NOx, PAN and Ozone Relationships

Springtime measurements of NO_x, ozone, PAN,J(NO₂), and other compounds were made near Ny-Ålesund,Svalbard (78°54N, 11°53E), in 1994 and Poker Flat,Alaska (65°08N, 147°29W), in 1995. At Svalbard medianmixing ratios for PAN and NO_x of 237 and 23.7 pptv,respectively, were observed. The median mixing ratios at Poker Flat for PANand NO_x were 79.5 and 85.9 pptv, respectively. These data areused to estimate thermal PAN decomposition using several differentapproaches. At Svalbard PAN decomposition was very small, while at PokerFlat up to 30 pptv/h PAN decomposed. At both sites the NO_x/PANratio increased with temperature between –10 and 20°C implyingthat PAN decomposition is an important NO_x source. In-situozone production was calculated from the measured NO, NO₂,O₃, J(NO₂), and temperature data, using thesteady state assumption Median ozone production was 605 pptv/h at PokerFlat, and one order of magnitude smaller at Svalbard during the daytime.Only at Poker Flat could a direct influence on the diurnal ozone cycle beobserved from in-situ production. These results imply that PAN decompositionis a major source of NO_x in the high latitude troposphere, andthat this contributes to the observed spring maximum in surface ozone.     

Upscaling of Land-Surface Parameters Through Inverse Stochastic SVAT-Modelling

A novel approach for upscaling land-surface parameters based on inverse stochastic surface-vegetation-atmosphere transfer (SVAT) modelling is presented. It allows estimation of effective parameters that yield scale invariant outputs e.g. for sensible and latent heat fluxes and evaporative fraction. The general methodology is used to estimate effective parameters for the Oregon State University Land-Surface Model, including surface albedo, surface emissivity, roughness length, minimum stomatal resistance, leaf area index, vapour pressure deficit factor, solar insolation factor and the Clapp–Hornberger soil parameter. Upscaling laws were developed that map the mean and standard deviation of the distributed land-surface parameters at the subgrid scale to their corresponding effective parameter at the grid scale. Both linear and bi-parabolic upscaling laws were obtained for the roughness length. The bi-parabolic upscaling law fitted best for the remaining land-surface parameters, except surface albedo and emissivity, which were best fitted with linear upscaling laws.     

贵州瓮安陡山沱组剖面碳同位素生物地球化学研究

在对扬子地台贵州瓮安陡山沱组剖面干酪根碳同住素组成进行分析后发现其变化显示了一定的规律性。碳同住素规律变化反映了最初的沉积信息,特别是有机质埋藏量的变化。获得的陡山沱期沉积岩中碳同位素组成研究结果初步反映了震旦一寒武交变期沉积环境的面貌;碳同位素组成变化规律可以用于反映扬子地台沉积层序和世界同期地层全球碳循环的对比和参考。为扬子区陡山沱期环境变化和生物演化提供了证据。δ^13Cker值在-32．3‰和-24．5‰(PDB)间漂移与δ^13Ccarb值在-4．9‰和3．6‰(PDB)间的变化,反映了当时海水的碳同位素组成。无机和有机碳同位素组成之差的△δorg-carb值沿剖面不断变化,是由于沉积有机质中有促进发酵功能的细菌数量比例变化所致。     

Banded structure of drifting macroalgae

A massive bloom of macroalgae occurred in the western Yellow Sea at the end of May, 2008, and lasted for nearly 2 months. The surface-drifting macroalgae was observed to accumulate in a pattern dominated by linear bands. The maximum length of individual algal bands exceeded 10 km and the distance between neighboring bands ranged from hundreds of meters to 6 km. Seven satellite images were analyzed to determine the distances between neighboring bands. Proportions of about 24%, 38%, and 22% are responsible for the separation distances smaller than 1 km, between 1 and 2 km, and between 2 and 3 km, respectively. The separation of about five percent of the bands exceeds 4 km. The probability distribution of the separation distance is quite close to log-normal which is that found in Langmuir circulation. However, the observed algal band separation greatly exceeds the distances between convergence lines reported in Langmuir circulation.