1,720,961 research outputs found
Response of grassland net primary productivity to dry and wet climatic events in four grassland types in Inner Mongolia
No full textAbstract Increasing frequency and intensity of climate extremes have profound impacts on grassland biodiversity functioning and stability. Using Moderate Resolution Imaging Spectroradiometer (MODIS) net primary productivity (NPP) data and standardized precipitation evapotranspiration index, we assessed the response of NPP to growing‐season and annual climate extremes and time‐lag of climatic conditions across four grassland types (meadow steppe, typical steppe, steppe desert, and desert steppe) in Inner Mongolia, China from the period 2000 to 2019. Results showed that annual NPP varied significantly across four grassland types, with the highest NPP in meadow steppe and the lowest in desert steppe. Annual NPP of all grassland types increased over the past 20 years, but NPP in meadow steppe and typical steppe decreased for the period 2012–2019. Irrespective of grassland type, the 1‐ and 2‐month time‐lag of climatic conditions showed significant effects on annual NPP. Growing‐season climate was found the better predictor of annual NPP in all grassland types than the annual climate. Compared with growing‐season normal climates, annual NPP was lowest in extreme dry events in all grasslands, while highest in extreme wet events in meadow steppe and typical steppe, and in moderate wet events in steppe desert and desert steppe. Typical steppe and steppe desert are highly vulnerable to the increasing intensity of climate extremes, as we found that the losses of NPP in these grasslands in extreme dry were almost double than that of moderate dry events. Surprisingly, for meadow steppe and desert steppe, the losses of NPP for both moderate and extreme dry events were almost the same, which highlights that a low‐intensity drought may have profound impacts on the annual NPP of these grasslands. The study provides the key insight in scientific basis to improve our understanding of the effects of climate extremes on grassland NPP, which is critical to sustainable management of grassland and maintain ecosystem stability
Dynamics of greenhouse gas fluxes and soil physico-chemical properties in agricultural and forest soils
No full textAbstract Examination of greenhouse gas (GHG) fluxes (CO2, CH4, and N2O) in soils is crucial for developing effective strategies to mitigate climate change. In this study, we investigated the GHG fluxes in agricultural and forest soils to explore the changes in soil GHG fluxes, and assess the relationships of GHGs with other physico-chemical properties. Results show that forest soils have a higher CO2 flux, while agricultural soils have a higher N2O flux due to fertilizer application and heterotrophic nitrification. Forest soils act as a CH4 sink, which are connected with increased porosity and decreased bulk density. In agricultural soils, CO2 and N2O were strongly linked with NH4+, soil temperature, pH, soil organic carbon, total nitrogen, plant-available phosphorous, and microbial biomass nitrogen (mbN) but were negatively connected with bulk density and microbial biomass carbon (mbC). In contrast to CO2 and N2O, CH4 in agricultural soils exhibited inverse relationships with all physico-chemical properties. In forest soils, CO2 and CH4 were positively correlated with soil temperature and mbC, and mbN and N2O were negatively correlated with bulk density and pH. This study highlights the critical need to comprehend the complex relationship between soil physico-chemical properties and GHG fluxes for effective climate change mitigation.Guangdong-Hong Kong Joint Laboratory for Water Securit
The Riparian Tree Species Composition and Diversity of the Midstream of Halda River in Chittagong, Bangladesh
No full textRiparian vegetation has been depleting in the many river basins of Bangladesh. Consequently, this study assessed the tree species composition, structure and diversity of the midstream area of the Halda River in Bangladesh. Twenty two quadrats (20 × 20m in size) were sampled. A total of 414 individual tree stems of ≥10 cm DBH of 36 tree species belonging to 31 genera and 15 families were enumerated. Density, Basal area and volume of the tree species were measured. Different diversity indices, i.e. Shannon-Wienners Diversity Index, Simpson's Dominance Index, Pielou’s Species Evenness Index, Margalef's and Menhinick’s richness index were calculated. Fabaceae was the most represented family with nine species, followed by Moraceae, Meliaceae and Anacardiaceae. Density, basal area and volume of the trees were 470.45 stem/ha, 19.09m²/ha and 139.42m³/ha, respectively. Samanea saman was found to be dominant, showing a maximum IVI, followed by v, Mangifer aindica, Eucalyptus camaldulensis and Artocarpus heterophyllus. The findings of the study will be helpful for the posterior researchers in their research work and their future tree based planning programs and conservation. So it is recommended that greater emphasis should be taken to proper management and conservation against over extraction and illegal felling for the maintenance of existing tree species composition and density
Community Mangrove Aqua-Silviculture (CMAS Culture): An Innovation and Climate Resilient Practice by the Sundarbans Mangrove Forest Dependent Rural Communities of Bangladesh
No full textTo adapt to the emergent global climate impacts, the local communities of Khulna, Satkhira and Bagerhat districts in South-Western Bangladesh have spontaneously promoted a number of social innovation using their innovative ideas and traditional knowledge. The present study highlights on this practice called as Community Mangrove Aqua-Silvi-Culture (CMAS) to cultivate some floral and faunal species of the Sundarbans mangrove ecosystem. CMAS is a plot of swampy land with 1 to 1.5 feet deep water bordered by a dyke of 0.5 to1.5 feet height from the water level. The mangrove plant species in CMAS includes Goalpata (Nypa fruticans), Goran (Ceriops tagal), Keora (Sonnerata species), Hargoza (Alanthus ilicifolius), and Baen (Avicennia Species). Besides, there is a canal of about 2-2.5 feet depth that runs along the farm dykes where fish (Telapia, Vetki, Amadi, Tengra, Carps), shrimp (Bagda) and crabs are cultured. For in depth analysis of CMAS, face-to-face interview was conducted in 18 CMAS farms to know about the cultivation method, cost-benefit aspects, environmental and social impact of this unique culture. The farm owners opined that after 13 to 14 months of plantation, which is the shortest in comparison with traditional practice, Golpata and Goran can be harvested usually in January to February. On the other hand, farming seasonality of fish and shrimps varies species to species. However, most of the fish species can be harvested in between May to June in each year. Interestingly, CMAS culture doesn’t need much care and maintenance costs. It is expected that the detailed analysis of CMAS will help the Sundarbans depended local communities more climate resilient
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Resilience to natural disasters: A case study on southwestern region of coastal Bangladesh
Get PDFBangladesh is one the disaster-prone countries in the world and has been suffering from different negative impacts. However, over the years, the coastal communities have developed their resilience capacity. This research assessed the local peoples’ resilience against natural disasters at Kazirchar village in Muladi Upazila of Barishal district of the coastal region. In this study, an extensive literature review on disaster resilience, well-structured questionnaire survey, and focus group discussions were conducted to collect primary data. Most of the indicators like show low values for socioeconomic resilience. The index value of literacy rate (1.12), primary health care facility (1.25), food consumption (1.30) and income (1.30) showed low disaster resilience. The result from the survey area implies a low level of institutional resilience (1.75). The reason behind low institutional resilience was weak disaster management activities. The index value of training (1.42), school/college (1.92), public awareness programme (2.14), and coordination (1) showed medium to very low of disaster resilience index. Results also showed that the villagers have low physical resilience. From the survey, Electricity supply (1.08), dependency on rainfall (1.08), cyclone and flood warning system (2.10), water bodies (1.56) and housing pattern (2.94) were the physical indicators of this village showed medium to low disaster resilience index. The overall disaster resilience ranges from 1 to 2.94. Depending on the score, disaster resilience level is divided into five categories from high (3>2.5), medium (2.5>2), low (2>1.5) to very low (1.5>1.0). Based on the resilience index the overall disaster resilience of Kazirchar village is low because of its low socio- economic (1.67), institutional (1.75) and physical (1.68) resilience values. The findings of this study will help to take necessary actions for building a more disaster resilient coastal Bangladesh
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