Livestock production and population census in Pakistan:Determining their relationship with agricultural GDP using econometric analysis

Livestock is a subsector of Pakistan agriculture which contributes approximately 56%of value addition in agriculture and nearly 11%to the gross domestic product(GDP).Livestock production makes a major contribution to agriculture value added services.In order to highlight the actual performance of livestock production and livestock and poultry products,the study explored the relationship between agricultural GDP and livestock product output,including milk,beef,mutton,poultry meat,eggs,wool,hair,skins,hides and bones,in Pakistan over the 35 year period from 1980 to 2015.Time series data were collected from the National Food Security and Research,the Economic Survey of Pakistan and the Pakistan Bureau of Statistics(various publications).Livestock data were analysed using the ordinary least squares(OLS)method and the Augmented Dickey-Fuller(ADF)test,and the results were interpreted using the Johansen co-integration test.Our study found that the output of milk,fat,eggs,bones and mutton has a positive,significant relationship to the agricultural GDP of Pakistan,while the output of beef,poultry meat,wool,hair,skins and hides has a negative,insignificant relationship to the agricultural GDP of Pakistan.Therefore,the study suggests that the government of Pakistan initiates new funding schemes for the development of the livestock sector.

Population Size, Genetic Diversity and Molecular Evidence of a Recent Population Bottleneck in Hynobius chinensis, an Endangered Salamander Species

Severe population declines can reduce species to small populations, offering permissive conditions for deleterious processes. For example, following such events, species can become prone to inbreeding and genetic drift which can lead to a loss of genetic diversity and evolutionary potentials. Hynobius chinensis is a poorly studied very rare and declining endangered amphibian species endemic to China in Changyang County. We investigated adult census population size by monitoring breeding populations from 2015 to 2018, developed microsatellite markers from the transcriptome and used them to investigate genetic diversity, and a population bottleneck in this species. We found H. chinensis in 4 different localities in a total area of 2.18 km^2 and estimated the overall adult census population size at 386–404 individuals. The adult census size（mean ± SE） per breeding pond ranged from 44 ± 6 to 141 ± 8 individuals and appeared smaller than that reported in closely related species in undisturbed habitats. We developed and characterized 13 microsatellite markers in total. Analysis of data at 7 loci（N = 118） in Hardy-Weinberg equilibrium gathered from the largest population showed that genetic diversity level was low. The average number of alleles per locus was 2.14. The observed and expected heterozygosities averaged 0.38 and 0.40, respectively. The inbreeding coefficient was –0.06. All tests performed to investigate a population bottleneck, i.e. The Garza-Williamson test, Heterozygosity excess test, Mode shift test of allele frequency, and effective population size estimates detected a population bottleneck. The contemporary and the historical effective population sizes were estimated at 36 and 234 individuals, respectively. We argue that as bottleneck effects, the studied population may have become prone to genetic drift and inbreeding, losing microsatellite alleles and heterozygosity. Our results suggest that populations of H. chinensismay have been extirpated in the study area.

A 100 m population grid in the CONUS by disaggregating census data with open-source Microsoft building footprints

In the Big Data era,Earth observation is becoming a complex process integrating physical and social sectors.This study presents an approach to generating a 100 m population grid in the Contiguous United States(CONUS)by disaggregating the US cen-sus records using 125 million of building footprints released by Microsoft in 2018.Land-use data from the OpenStreetMap(OSM),a crowdsourcing platform,was applied to trim original footprints by removing the non-residential buildings.After trimming,several metrics of building measurements such as building size and build-ing count in a census tract were used as weighting scenarios,with which a dasymetric model was applied to disaggregate the American Community Survey(ACS)5-year estimates(2013-2017)into a 100 m population grid product.The results confirm that the OSM trimming process removes non-residential buildings and thus provides a better representation of population distribution within complicated urban fabrics.The building size in the census tract is found in the optimal weighting scenario.The product is 2.5Gb in size containing 800 million populated grids and is currently hosted by ESRI(http://arcg.is/19S4qK)for visualization.The data can be accessed via https://doi.org/10.7910/DVN/DLGP7Y.With the accel-erated acquisition of high-resolution spatial data,the product could be easily updated for spatial and temporal continuity.

A Proportion Analysis of City/Town Population in China's Fourth Census in 1990

On the basis of the analysis of the standards for the city/town populationstatistics in the past censuses,the author makes a proportional analysis of the city/townpopulation according to the data obtained from the fourth census,and points out the dis-crepancies in the standard for the the city/town population statistics used in the fourthcensus and proposes ways for their correction.

Spatio-Temporal Changes of Population Density and Urbanization Pattern in China(2000–2010)

Population distribution and their temporal variation are a direct proxy of urbanization. This study evaluates the population density variation of China between 2000 and 2010 at the township level by using the data of the fi fth and sixth national population censuses. The urbanization patterns of China in 2000 and 2010 are depicted based on the population densities at various levels and the urbanization process of China between 2000 and 2010 is then analyzed through a comparative approach. It also tries to visualize the population density dynamics and urbanization pattern variations of China at the township level.

From the past to the future:what we learn from China’s 2020 Census

The population of China has entered an era of low fertility and aging,with a slower growth rate in the last decade.This commentary briefly reviews demographic changes in China in the last seven decades with some important years of change in mortality,fertility and urbanization,and discusses future trends according to the information provided by the 2020 Census.China has experienced“compressed”population change,and population aging will continue to advance,meanwhile the size of the population is expected to reach its peak in the near future.To prepare proper response to the challenges proactively,institutional change which adapts to population changes is necessary.