Forest characteristics,population structure and growth trends of threatened relict Pseudotsuga forrestii in China

Pseudotsuga forrestii is a relict evergreen coniferous tree species in Pinaceae endemic to China.P.forrestii tree numbers have greatly decreased due to deforestation,over-utilization and habitat degradation.Here we clarify P.forrestii community types,structure,species diversity,seedling recruitments and growth trends.We identified four P.forrestii community types:(1)Pseudotsuga forrestii-Quercus guyavifolia-Acer davidii evergreen coniferous and broad-leaved mixed forest;(2)Pseudotsuga forrestii-Pinus yunnanensis-Quercus guyavifolia evergreen coniferous and broad-leaved mixed forest;(3)Pseudotsuga forrestii evergreen coniferous forest;(4)Pseudotsuga forrestii-Abies georgei var.smithii evergreen coniferous forest.P.forrestii forests are characterized by both warm temperate and temperate affinities.Simpson diversity,Pielou evenness,Shannon-Wiener diversity indices ranged from 0.75 to 0.76,0.74-0.81,and 1.62-1.93,respectively,with no significant differences among the four forest types.The forest stratification was multilayered.The canopy layer was generally 10-25 m tall,with the emergent layer reached 25-42 m.DBH and age structures of P.forrestii showed multimodal distributions.Its maximum age P.forrestii was 570 years with a DBH of 143 cm.The growth of annual ring width of P.forrestii was slow,and generally decreased with age,whereas the basal area at the breast height increased with age.Established seedlings/saplings were mainly found in unstable micro-habitats.Regeneration of P.forrestii depends on moderate natural disturbances.Finally,we provide recommendations for P.forrestii conservation.

Trends of Population Growth in China:Maximum Number Will Exceed 1.5 Billion

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Effects of Climate and the Urban Heat Island Effect on Urban Tree Growth in Houston

The growing conditions of urban trees differ substantially from forest sites and are mainly characterized by small planting pits with less water, nutrient and aeration availability, high temperatures and radiation inputs as well as pollution and soil compaction. Especially, global warming can amplify the negative effects of urban microclimates on tree growth, health and well-being of citizens. To quantify the growth of urban trees influenced by the urban climate, ten urban tree species in four climate zones were assessed in an overarching worldwide dendrochronological study. The focus of this analysis was the species water oak (Quercus nigra L.) in Houston, Texas, USA. Similar to the overall growth trend, we found in urban trees, water oaks displayed an accelerated growth during the last decades. Moreover, water oaks in the city center grew better than the water oaks growing in the rural surroundings of Houston, though this trend was reversed with high age. Growth habitat (urban, suburban, rural and forest) significantly affected tree growth (p < 0.001) with urban trees growing faster than rural growing trees and forest trees, though a younger age of urban trees might influence the found growth patterns. Growing site in terms of cardinal direction did not markedly influence tree growth, which was more influenced by the prevalent climatic conditions of Houston and the urban climate. Higher temperatures, an extended growing season and eutrophication can cause an accelerated growth of trees in urban regions across, across all climatic zones. However, an accelerated growth rate can have negative consequences like quicker ageing and tree death resulting in higher costs for new plantings and tree management as well as the decrease in ecosystem services due to a lack of old trees providing greatest benefits for mitigating the negative effects of the urban climate.

THE ANALYSIS OF CHILD′S GROWTH TREND DURING 1958～1995 IN XI′AN CITY

The paper analyzed the growth level and velocity to find the growth trend with the data collected in 8 investigations on growth of children aged 7～17 years in 1958～1995 in Xi′an. The results showed that child′s growth level was elevated with the passage of years and was the lowest in 1962, the highest in 1995 during the 38 years. The height of boy of the same age in 1995 has average increased by 9 59 cm over 1958 and girl 8 38 cm. The weight of boy of the same age in 1995 has averagely increased by 8 35 kg over 1958 and girl 5 90 kg. The chest girth of boy of the same age in 1995 has average increased by 5 69 cm over 1958 and girl 4 66 cm. The growth level of children aged 9～15 years had greater increase than others in 7～17 years of age. The average increment per 10 years of boy's height was 2 57 cm and girl's 2 26 cm. The average increment of per 10 years of boy's weight was 2 17 kg and girl's 1 56 kg. The average increment of per 10 years of boy's chest girth was 1 50 cm and girl's 1 23 cm. The analysis of the growth velocity in different period during 38 years showed the velocity in 1958～1962 was a negative value and indicated a growth retard, but the velocity in 1962～1964 was the fastest and indicated a catch up growth. And then, growth velocities of height, weight and chest girth were different in different period. The analysis of the growth curves of height, weight and chest girth showed that the 2 cross ages were 1～3 years of age ahead of time and menarche and emission also were ahead of time that during the 38 years indicated there is a child's growth acceleration in Xi′an and the trend of child's growth acceleration could continue if there are more and better nourishment, sports requisites, health care and housing conditions.

Standardization of Qilian Juniper ring-width series in the eastern margin of the Qaidam Basin

Standardization is one of the important procedures in dendroclimatology. We used abundant Qilian juniper （Sabina przewalskii Kom.） tree-ring samples from the eastern margin of the Qaidam Basin to develop a new standardization method, i.e. total growth curve （TGC）. The samples that contained the complete pith and reached to the growing culmination around the 40th-60th year were used to fit TGC, and the generalized negative exponential function was used to fit the curve. Usually, most cores cannot reach the arboreal pith for some reasons and it is difficult to determine the arboreal cambial age. The empirical model of initial radial growth （IRG） was employed to estimate the number of rings missing from the pith by the same data and IRG model explained 90.9% of the variance. When developing the chronology, the cambial ages of cores that contained the complete pith were regarded as beginning from the first year and others were determined by the numbers of missing and included rings in the core. Standardization was accomplished by dividing each tree-ring series by corresponding TGC. The chronologies developed by TGC can retain more low-frequency variational information and TGC helps to develop more reliable tree-ring width chronology.

An Analysis of China’s Economic Growth Trend(1998-2002)

The growth of the world economy in 2001 featured significant slowdowns, with various developed countries plunging into economic recessions or economic downturns synchronously. Against this context, China was able to maintain a 7.3 percent growth. A simple direct comparison of economic growth of all countries shows that China outshone all the others.

Will China be Able to Avoid the Japan Syndrome？

Following the 1973 oil crisis, Japan ＇s economic growth slowed down substantially and its asset prices overshot their long-term trend. The economic performance of this episode of the Japanese history has been dubbed the ＂Japan syndrome.＂ China has followed Japan＇s export-led growth model and the the world economy following the oil crisis current worm economy very much resembles It is then a legitimate question to ask whether China is likely to follow in Japan＇s steps and experience a major slowdown in its growth. The present paper shows that China can do a better job than Japan primarily because its large size allows the country to benefit from internal convergence. Based on the estimation of a growth equation using cross-country panel data, the paper forecasts that under reasonable assumptions about the growth rate of the worm economy and China ＇s investment rate, China could maintain reasonably high growth rates in the next 10 years.

Knowledge diffusion trajectories in the Pythagorean fuzzy field based on main path analysis

Purpose-The purpose of this article is to conduct a main path analysis of 627 articles on the theme of Pythagorean fuzzy sets(PFSs)in the Web of Science(WoS)from 2013 to 2020,to provide a conclusive and comprehensive analysis for researchers in this field,and to provide a study on preliminary understanding of PFSs.Design/methodology/approach-The research topic of Pythagorean fuzzy fields,through keyword extraction and describing the changes in characteristic themes over the past eight years,are firstly examined.Main path analysis,including local and global main paths and key route paths,is then used to reveal the most influential relationships between papers and to explore the trajectory and structure of knowledge transmission.Findings-The application of Pythagorean fuzzy theory to the field of decision-making has been popular,and combinations of the traditional Pythagorean fuzzy decision-making method with other fuzzy sets have attracted widespread attention in recent years.In addition,over the past eight years,research interest has shifted to different types of PFSs,such as interval-valued PFSs.Research limitations/implications-This paper implicates to investigate the growth in certain trends in the literature and to explore the main paths of knowledge dissemination in the domain of PFSs in recent years.Originality/value-This paper aims to identify the topics in which researchers are currently interested,to help scholars to keep abreast of the latest research on PFSs.