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The Association Between Daily Physical Activity and Risk of Hypertension in Middle-Aged and Older Adults:A Nationwide Cohort Study in China
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作者 Junhua Zhang Jie Rong +1 位作者 Hui Zhang Yongmei Yan 《Journal of Clinical and Nursing Research》 2024年第9期83-92,共10页
Physical activity (PA) plays a key role in the treatment of hypertension, and moderate to vigorous PA has been documented to lower the risk of developing hypertension. However, dose-response relationships between PA a... Physical activity (PA) plays a key role in the treatment of hypertension, and moderate to vigorous PA has been documented to lower the risk of developing hypertension. However, dose-response relationships between PA and hypertension are not consistent, and little is known about this relationship within the Chinese middle-aged and older people. We investigated the relationship between PA and hypertension within this population using China Health and Nutrition Survey 1991-2015 data. Physical activity was expressed in terms of the metabolic equivalent task (MET) and participants were divided into groups according to quartiles, namely, Q1 (< 32.97 METs-h/w), Q2 (32.97-60.38 METs-h/ w), Q3 (60.38-98.95 METs-h/w), and Q4 (> 98.95 METs-h/w). Compared with the Q1 group, the odds ratio of risk with hypertension (95% CIs) after adjusting for confounding factors were 0.63 (0.35, 1.12), 0.49 (0.28, 0.86), and 0.62 (0.35, 1.09) for those in Q2, Q3, and Q4, respectively. Restricted cubic spline functions were used and a U-shaped relationship between physical activity and hypertension risk was found, indicative of an optimal level of physical activity, which was found to be 112 METs-h/w. Our data suggest maintenance of optimal levels of total daily physical activity may be important for preventing hypertension in Chinese adults over the age of 40. 展开更多
关键词 Physical activity HYPERTENSION middle age Older adults
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Radiometric Dating of Ignimbrite from Inner Mongolia Provides no Indication of a Post-Middle Jurassic Age for the Daohugou Beds 被引量:30
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作者 GAO Ke-Qin REN Dong 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2006年第1期42-45,共4页
Lacustrine deposits exposed at Daohugou, Inner Mongolia, China, have yielded superbly preserved vertebrate fossils. The fossil beds were first misinterpreted as of Early Cretaceous age, based on alleged occurrences of... Lacustrine deposits exposed at Daohugou, Inner Mongolia, China, have yielded superbly preserved vertebrate fossils. The fossil beds were first misinterpreted as of Early Cretaceous age, based on alleged occurrences of key fossils of the Jehol Biota. Compelling evidence revealed by more rigorous research involving regional biostratigraphy, radiometric dating, and paleontology supports the Middle Jurassic age of the fossil beds. Despite the awesome evidence for the Middle Jurassic age of the Daohugou beds, the age dispute has been resurrected recently by invoking an overturned stratigraphic sequence. A careful review of the data, however, found no evidence that this sequence has been overturned. In addition, many of the assumptions, on which the conjecture of the fossil beds being post- Middle Jurassic is imprudently based, are self-contradictory or otherwise misleading. Thus, the post- Middle Jurassic age of the Daohugou beds as an unfounded conclusion can readily be dismissed. 展开更多
关键词 Daohugou beds Inner Mongolia middle Jurassic age dispute radlometric dating
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Shift work aggravates metabolic syndrome development among early-middle-aged males with elevated ALT 被引量:4
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作者 Yu-Cheng Lin Tun-Jen Hsiao Pau-Chung Chen 《World Journal of Gastroenterology》 SCIE CAS CSCD 2009年第45期5654-5661,共8页
AIM: To examine whether shift work accelerates metabolic syndrome (MetS) development among early middle-aged males with elevated alanine aminotransferase (e-ALT).METHODS: A retrospective, observational followup study ... AIM: To examine whether shift work accelerates metabolic syndrome (MetS) development among early middle-aged males with elevated alanine aminotransferase (e-ALT).METHODS: A retrospective, observational followup study on MetS development at a 5-year interval was conducted using health examination data. Nine hundred and ninety six male employees not fulfi lling MetS criteria at screening were enrolled. Age, MetScomponents, liver enzymes, serological markers for viral hepatitis, abdominal ultrasound, insulin resistance status, lifestyles, and workplace factors were analyzed.RESULTS: The prevalence of elevated serum ALT (> 40 U/L, e-ALT) at baseline was 19.1%. There were 381 (38.3%) workers with long-term exposures to day-night rotating shift work (RSW). 14.2% of subjects developed MetS during follow-up. After 5 years, the workers with e-ALT had significantly unfavorable changes in MetS-components, and higher rates of MetS development, vs subjects with normal baseline ALT levels. Workers with both baseline e-ALT and 5-year persistent RSW (pRSW) exposure had the highest rate of MetS development. Also, e-ALT-plus-pRSW workers had a significant increase in MetS-components atfollow-up, compared with the other subgroups. After controlling for potential confounders, e-ALT-plus-pRSW workers posed a signifi cant risk for MetS development (odds ratio, 2.7; 95% confi dence interval, 1.4-5.3, vs workers without baseline e-ALT nor pRSW). CONCLUSION: We suggest that all early middle-aged male employees with e-ALT should be evaluated and managed for MetS. Particularly in terms of job arrangements, impacts of long-term RSW on MetS development should be assessed for all male employees having baseline e-ALT. 展开更多
关键词 Alanine aminotransferase Early middle aged MALE Metabolic syndrome Shift work
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Influencing factors analysis of spontaneous knee joint osteoarthritis among middle aged and old aged pople in Xi'an 被引量:4
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作者 王伟 王坤正 +4 位作者 党晓谦 柏传毅 王春生 时志斌 马树强 《Journal of Medical Colleges of PLA(China)》 CAS 2007年第3期179-184,共6页
Objective:To explore the prevalence rate of knee joint osteoarthritis and its pathogenetic fea- tures among the middle-aged and old aged people in the urban and rural area of Xi'an.Methods:From May to October 2005... Objective:To explore the prevalence rate of knee joint osteoarthritis and its pathogenetic fea- tures among the middle-aged and old aged people in the urban and rural area of Xi'an.Methods:From May to October 2005,1538 Han nationality above 40 years in Xi'an were investigated according to strati- fied and cluster random sampling.The same questionnaire was delivered to subjects who had been given normotopia and lateral position radiographic examination in both knees.Excluded from etiological arthri- tis,some subjects with clinical symptoms and a radiographic grade (beyond Kellgren & Lawrence gradeⅡ) were finally diagnosed as spontaneous knee joint osteoarthritis.All analyses were performed with SPSS 13.0 and t test,U test.Single factor analysis and multiple logistic regression analysis were used to analyze dates.Results:The total prevalence of spontaneous knee joint osteoarthritis was 12.1% with 2.5% and 2.1% for right and left knees,respectively.The prevalence of knee joint osteoarthritis in wom- en was 2.5 times of that in men (17.2% vs 6.8%,P=0.000).the osteophyte prevalence in women was 2.3 times of that in men (26.5% vs 11.4%,P=0.000).The prevalence of knee joint osteoarthritis and osteophyte increased with the growth of age.So did the symptomatic knee,except for the age group of 56- 60 years and 66-70 years.The prevalence of symptomatic knee joint for urban area was significantly higher than that for rural area (56.3% vs 45.3%,P=0.003).In women,the prevalence of knee joint os- teoarthritis increased significantly with the increasing of body mass index,which had not been observed in men.Female and obesity are the risk factors for osteoarthritis,but bean and its products and meat could prevent the osteoarthritis.Conclusion:Old age,female and obesity serve as risk factors for knee joint os- teoarthritis. 展开更多
关键词 OSTEOARTHRITIS KNEE SPONTANEOUS EPIDEMIOLOGY middle and old aged
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How forest age impacts on net primary productivity: Insights from future multi-scenarios
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作者 Lei Tian Yu Tao +2 位作者 Simms Joanna Annikki Mäakelä Mingyang Li 《Forest Ecosystems》 SCIE CSCD 2024年第5期708-719,共12页
Forest net primary productivity(NPP)constitutes a key flux within the terrestrial ecosystem carbon cycle and serves as a significant indicator of the forests carbon sequestration capacity,which is closely related to f... Forest net primary productivity(NPP)constitutes a key flux within the terrestrial ecosystem carbon cycle and serves as a significant indicator of the forests carbon sequestration capacity,which is closely related to forest age.Despite its significance,the impact of forest age on NPP is often ignored in future NPP projections.Here,we mapped forest age in Hunan Province at a 30-m resolution utilizing a combination of Landsat time series stack(LTSS),national forest inventory(NFI)data,and the relationships between height and age.Subsequently,NPP was derived from NFI data and the relationships between NPP and age was built for various forest types.Then forest NPP was predicted based on the NPP-age relationships under three future scenarios,assessing the impact of forest age on NPP.Our findings reveal substantial variations in forest NPP in Hunan Province under three future scenarios:under the age-only scenario,NPP peaks in 2041(133.56TgC·yr^(−1)),while NPP peaks three years later in 2044(141.14TgC·yr^(−1))under the natural development scenario.The maximum afforestation scenario exhibits the most rapid increase in NPP,with peaking in 2049(197.95TgC·yr^(−1)).However,with the aging of the forest,NPP is projected to then decrease by 7.54%,6.07%,and 7.47%in 2060,and 20.05%,19.74%,and 28.38%in 2100,respectively,compared to their peaks under the three scenarios.This indicates that forest NPP will continue to decline soon.Controlling the age structure of forests through selective logging,afforestation and reforestation,and encouraging natural regeneration after disturbance could mitigate this declining trend in forest NPP,but implications of these measures on the full forest carbon balance remain to be studied.Insights from the future multi-scenarios are expected to provide data to support sustainable forest management and national policy development,which will inform the achievement of carbon neutrality goals by 2060. 展开更多
关键词 Net primary productivity forest age NPP-age relationships NPP projections AFforestATION
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Effects of Warm Needling at Zusanli(ST 36)on NO and IL-2 Levels in the Middle-Aged and Old People 被引量:2
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作者 李苏 陈开阳 +3 位作者 吴英 焦健慧 陶立富 王友京 《Journal of Traditional Chinese Medicine》 SCIE CAS CSCD 2003年第2期127-128,共2页
42 middle-aged and old people at the age between 55-70 years were selected and given the warm needling at Zusanli (ST 36), and their IL-2 and NO contents of peripheral blood before and after acupuncture were determine... 42 middle-aged and old people at the age between 55-70 years were selected and given the warm needling at Zusanli (ST 36), and their IL-2 and NO contents of peripheral blood before and after acupuncture were determined. The results showed that IL-2 and NO contents increased significantly after the warm needling (P<0.01). 展开更多
关键词 Acupuncture Therapy Acupuncture Points aged Female Humans Hypertension INTERLEUKIN-2 Male middle aged MOXIBUSTION Nitric Oxide Sleep Initiation and Maintenance Disorders
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One Hundred and Seven Middle-Aged and Senile Cases of Coronary Heart Disease with Ventricular Premature Beat Treated by Qing Xin An Shen Fang 被引量:1
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作者 贾钰华 孙学刚 +3 位作者 贾满盈 崔志英 李崇信 刘煜 《Journal of Traditional Chinese Medicine》 SCIE CAS CSCD 2001年第4期247-251,共5页
The therapeutic principle of clearing away the heart-heat to induce tranquilization was adopted in 107 middle-aged and senile patients with ventricular premature beat of coronary heart disease on the basis of pathogen... The therapeutic principle of clearing away the heart-heat to induce tranquilization was adopted in 107 middle-aged and senile patients with ventricular premature beat of coronary heart disease on the basis of pathogenic features of phlegm, heat, blood stasis and deficiency in this condition. Qing Xin An Shen Fang ([symbol: see text] a formula for clearing away the heart-heat to induce tranquilization) was used in the treatment group and compared with mexiletine and Fu Fang Dan Shen Tablets ([symbol: see text] Compound Salvia Tablets) used in the control group. The results turned to be that the markedly effective rate was 85.1% and the total effective rate 96.3% in the treated group, better than that in the control group, with the former having a good antihypertensive and antihyperlipemic effect and an effect of improving microcirculation and clinical symptoms. 展开更多
关键词 aged aged 80 and over Coronary Disease Drugs Chinese Herbal Female Humans Male middle aged Ventricular Premature Complexes
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Tectonic Environments of the Yan-Liao Rift during Earth's Middle Age(1.7~0.75 Ga): Evidence from Mafic Dyke Swarms in Eastern Hebei, North China 被引量:1
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作者 WANG Chong PENG Peng +1 位作者 WANG Xinping YANG Shuyan 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第S1期45-46,共2页
During the past decade,generations of Precambrian mafic dykes/sills have been investigated and revealed in the North China Craton(NCC).Researchers identified more than 20 episodes of Precambrian dyke swarms,
关键词 North China Tectonic Environments of the Yan-Liao Rift during Earth’s middle age Evidence from Mafic Dyke Swarms in Eastern Hebei Ga
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Effects of Ving Tsun sticking-hand training on upper-limb sensorimotor performance in community-dwelling middle-aged and older adults: A randomized controlled trial
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作者 Joanne W.Y.Chung Shirley S.M.Fong +4 位作者 Yang Gao Timothy T.T.Yam Yvonne T.C.Chak Joyce C.Y.Leung Thomas K.S.Wong 《International Journal of Nursing Sciences》 CSCD 2020年第1期29-34,共6页
Objective:To evaluate the effects of Ving Tsun(VT)sticking-hand training on upper-limb joint position sense and muscular performance in community-dwelling middle-aged and older adults.Methods:Thirty-three adults were ... Objective:To evaluate the effects of Ving Tsun(VT)sticking-hand training on upper-limb joint position sense and muscular performance in community-dwelling middle-aged and older adults.Methods:Thirty-three adults were randomly allocated to either a VT group or a control group.The VT group received VT sticking-hand training twice per week for 3 months.Measurements were taken before and after the intervention period.The primary outcome was elbow-joint repositioning error,which was measured by an elbow-joint passive positioning and active repositioning test using a universal goniometer.Secondary outcomes were upper-limb muscles'peak force and time taken to reach peak force as measured by a hand-held dynamometer.Results:No significant time,group or time-by-group interaction effects were found for elbow-joint repositioning error or upper-limb muscle peak force outcomes.Shoulder flexor time to peak force decreased by 33.8%from pre-test to post-test in the VT group(P=0.007).Shoulder abductor,internal and external rotator,and elbow extensor times to peak force decreased by 30.0%-35.9%in the VT%roup(P<0.05)and by 30.4%-37.1%in the control group(P<0.05).Conclusions:VT sticking-hand training does not improve elbow-joint position sense or the maximum strength of upper-limb muscles in middle-aged and older adults.However,VT can improve shoulder flexor muscles'time to reach peak force in these populations.VT had no obvious effect on the time required to reach peak force in other shoulder muscles and elbow extensors. 展开更多
关键词 aged Exercise movement techniques Joint position sense middle aged Muscle strength UPPER EXTREMITIES
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Analysis of the Variations of Body Build of Middle-and Old-aged and Research on the Prototype
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作者 李兴刚 沈卫勤 《Journal of China Textile University(English Edition)》 EI CAS 2000年第4期61-65,共5页
The characteristics of body build of middle - and old -aged women and its rule of variations as well as the basic sizes of various parts are discussed. All these are based on the body measurements of this age group, a... The characteristics of body build of middle - and old -aged women and its rule of variations as well as the basic sizes of various parts are discussed. All these are based on the body measurements of this age group, and also on the statistical studies of the measurement data. By setting the regression equation, the calculating formulae of various control parts are obtained, thus establishing the prototype of this age group for women. 展开更多
关键词 middle - and old - aged characteristics of BODY BUILD APPAREL sizes and types PROTOTYPE
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Study on Body Form and Garment Size Series of the Middle Age and Aged People
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作者 刘瑜 郁进明 《Journal of Donghua University(English Edition)》 EI CAS 2003年第4期60-63,共4页
This paper was designed to analyze on the data, which was obtained from 'National Physique Fitness Investigation Report (2000)'. In order to get the typical body form and figure type of the middle age and aged... This paper was designed to analyze on the data, which was obtained from 'National Physique Fitness Investigation Report (2000)'. In order to get the typical body form and figure type of the middle age and aged people, it was focused on the body form data of this group (age 40 - 60). After calculation and analyzing, the distinguishing feature of body form and the distribution of figure type were deduced. Finally, the re-classification of body form for Chinese middle age and aged people was suggested. It as also suggested that a new garment size series especially for the middle age and aged should be built to fit for these people. This conclusion would be useful and significant to design and production for clothing company, especially that who take the aged people as their target consumer. 展开更多
关键词 Body form body form classification garment size and series middle age and aged people
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Georgia and Europe in the Early Middle Ages
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作者 Bejan Javakhia 《Journal of Literature and Art Studies》 2018年第12期1702-1712,共11页
The article deals with relations of Georgia to Europe in the late antique period and the early Middle Ages.The analyses rests on the Byzantium and the Western European,as well as on Georgian written sources:historical... The article deals with relations of Georgia to Europe in the late antique period and the early Middle Ages.The analyses rests on the Byzantium and the Western European,as well as on Georgian written sources:historical chronicles,hagiographic texts and other information,reflecting political relations of the Iberia and Lazika—those-days kingdoms,located on the territory of Georgia—to the Western European and Byzantine space.The offered analysis will concentrate on the shared characteristics of European space in the Middle Ages and will compare them to the general tendencies of development of Georgia in the same period.This enables to draw conclusion that Georgia was the part of the unified Christian space of the early Middle Ages. 展开更多
关键词 Georgia EUROPE middle ageS LATE ANTIQUE
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The Issue of Genealogy of Armenians, Georgians and Other Caucasian Nations in the Historiography of the Middle Ages
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作者 Manana Sanadze 《Journal of Literature and Art Studies》 2017年第2期207-225,共19页
The paper shows that the story about the origin of Armenians, Georgians and other Caucasians from a common ancestor, namely, from Targamos (Togormah)—The Life of the Fore-Patriarchs and Ancestors of the Georgian King... The paper shows that the story about the origin of Armenians, Georgians and other Caucasians from a common ancestor, namely, from Targamos (Togormah)—The Life of the Fore-Patriarchs and Ancestors of the Georgian Kings, which is represented in the introductory part of The Georgian Chronicles and is dated back to the end of the11th, is a compiled work that mainly contains, on the one hand, an old Georgian genealogical-geographical story about Tarshish’s son Kartlos (Iber) and his six brothers ( Egros, Movakan, Heros, Bardos, Lekan and Caucas)created at the end of the 6th c.-first half of the 8th c. based on Byzantine works, and on the other hand, a genealogical story created in old Armenian historiography about Targamos and his son Hayk that went through certain steps of development as well. In the process of synthesizing, Togormah (Targamos) and his son Hayk (Haos)were inserted between Tarsish and his son Kartlos (Iber), which violated the Biblical scheme as well as the structure of the sentence in which the insertion was made. The goal of developing the synthesized scheme was to bring evidence of the common origin of Georgians and Armenians, as long as quite a large number of Armenians,because of the incorporation of a large part of Armenian territories within Georgian borders, became citizens of Georgia. At the same time, the story also offers a justification in the eyes of the Muslim world for the claims of Georgia for Armenian territories. According to the newly-created synthesized scheme, Georgia was “the successor brother” of Armenia(Haos//Hayk) and considering the absence of Armenian states, i.e., “the elder brother”,Georgia was the only legal heir of Armenian territories. 展开更多
关键词 Georgians Armenians CAUCASIANS middle ageS GENEALOGY
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Research on the Gender and Age Differences of Middle School Students' Shame Sense
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作者 Shenghua QI 《International Journal of Technology Management》 2013年第6期64-67,共4页
In order to ensure the existence of the gender and age differences of middle school students' shame, 1258 Shanghai middle school students are surveyed with the help of the Middle school students' shame measurement s... In order to ensure the existence of the gender and age differences of middle school students' shame, 1258 Shanghai middle school students are surveyed with the help of the Middle school students' shame measurement scale with the combination of delaminating and random sampling. The results of questionnaire show that there are significant gender differences in middle school students' shame and the average scores of male students' shame are higher than those of female students. Besides, there does exist significant age differences in middle school students' shame, but it is not simple linear relationship between the feeling of shame and ages. The feeling of shame reaches maximum at the age of 14 and intervention should be given at this age, which young students feel sensitive most. It is suggested that collective remission of the shame should be offered to middle school students with the methods such as physical exercises, persuasion etc. 展开更多
关键词 middle School Student SHAME Gender Difference age Difference
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China's National Image in Western Travels in the Middle Ages
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作者 LI Chaojun 《Journal of Landscape Research》 2019年第1期46-48,52,共4页
The cognition of the image of China in the West during the Middle Ages is a historical base map for the formation of China's image in the eyes of Western travelers in China since the 19 th century. During the Midd... The cognition of the image of China in the West during the Middle Ages is a historical base map for the formation of China's image in the eyes of Western travelers in China since the 19 th century. During the Middle Ages, with the Crusades and the Eastward March of the Mongol Empire, the exchanges between China and Europe were frequent. For political and religious purposes, Western missionaries gradually increased in China. From the expansion of the concept of time and space, Western travelers came to China to explore the world outside the Mediterranean. For the needs of literary creation, Western writers began to write Chinese travels while traveling to China. The texts about China's images created by missionaries, travelers and writers are intertwined, depicting a vivid China's national image. 展开更多
关键词 middle ageS Travels The IMage of China
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Soil Organic Carbon Pool and Its Influencing Factors in Rubber Planted Forest Ecosystem at Different Ages in West Hainan Province 被引量:4
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作者 管利民 吴志祥 +2 位作者 杨川 谢贵水 周兆德 《Agricultural Science & Technology》 CAS 2012年第10期2163-2168,共6页
In this research,the contents of organic carbon in soil profiles in rubber forests in west of Hainan were measured and storage quantity of oganic carbon was estimated.The results indicated that contents of organic car... In this research,the contents of organic carbon in soil profiles in rubber forests in west of Hainan were measured and storage quantity of oganic carbon was estimated.The results indicated that contents of organic carbon in soils of ecosystem of rubber forests at different ages were 6.20-14.36 g/kg;organic carbon in soils of rubber forests reduced upon soil depth;the contents differed signigicantly in soils at 0-60 cm in rubber forest at 33 a,but differed little in soils in rubber forests at other ages;the contents were of significant differences in soils in rubber forests at different ages;organic carbon concentrated in soils at 0-30 cm;the storage quantities of organic carbon in rubber forests at 5,10,19 and 33 a were 76.85,74.48,81.74 and 85.31 t/hm^2.Climate,soil property,accumualtion and decomposition of fallen materials,forest age and management are dominant factors influencing accumulation of organic carbon in soils of rubber forest. 展开更多
关键词 Rubber planted forest forestry age Soil organic carbon
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Forest management required for consistent carbon sink in China’s forest plantations 被引量:8
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作者 Zhen Yu Weibin You +2 位作者 Evgenios Agathokleous Guoyi Zhou Shirong Liu 《Forest Ecosystems》 SCIE CSCD 2021年第4期726-734,共9页
Background:Forest is the largest biomass carbon(C)pool in China,taking up a substantial amount of atmospheric carbon dioxide.Although it is well understood that planted forests(PFs)act as a large C sink,the contributi... Background:Forest is the largest biomass carbon(C)pool in China,taking up a substantial amount of atmospheric carbon dioxide.Although it is well understood that planted forests(PFs)act as a large C sink,the contribution of human management to C storage enhancement remains obscure.Moreover,existing projections of forest C dynamics suffer from spatially inconsistent age and type information or neglected human management impacts.In this study,using developed PF age and type maps and data collected from 1371 forest plantation sites in China,we simulated biomass C stock change and quantified management impacts for the time period 2010-2050.Results:Results show that future forest biomass C increment might have been overestimated by 32.5%-107.5% in former studies.We also found that age-related growth will be by far the largest contributor to PF biomass C increment from 2010 to 2050(1.23±0.002 Pg C,1 Pg=10^(15) g=1 billion metric tons),followed by the impact of human management(0.57±0.02 Pg C),while the contribution of climate is slight(0.087±0.04 Pg C).Besides,an additional 0.24±0.07 Pg C can be stored if current PFs are all managed by 2050,resulting in a total increase of 2.13±0.05 Pg C.Conclusions:Forest management and age-related growth dominate the biomass C change in PFs,while the effect of climatic factors on the accumulation is minor.To achieve the ambitious goal of forest C stock enhancement by 3.5 Pg from 2020 to 2050,we advocate to improve the management of existing forests and reduce the requests for more lands for forest expansion,which helps mitigate potential conflicts with agricultural sectors.Our results highlight that appropriate planning and management are required for sustaining and enhancing biomass C sequestration in China’s PF. 展开更多
关键词 Planted forest Human management forest biomass carbon forest age forest expansion Climate change
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Mapping forest age using National Forest Inventory,airborne laser scanning,and Sentinel-2 data 被引量:6
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作者 Johannes Schumacher Marius Hauglin +1 位作者 Rasmus Astrup Johannes Breidenbach 《Forest Ecosystems》 SCIE CSCD 2020年第4期793-806,共14页
Background:The age of forest stands is critical information for forest management and conservation,for example for growth modelling,timing of management activities and harvesting,or decisions about protection areas.Ho... Background:The age of forest stands is critical information for forest management and conservation,for example for growth modelling,timing of management activities and harvesting,or decisions about protection areas.However,area-wide information about forest stand age often does not exist.In this study,we developed regression models for large-scale area-wide prediction of age in Norwegian forests.For model development we used more than 4800 plots of the Norwegian National Forest Inventory(NFI)distributed over Norway between latitudes 58°and 65°N in an 18.2 Mha study area.Predictor variables were based on airborne laser scanning(ALS),Sentinel-2,and existing public map data.We performed model validation on an independent data set consisting of 63 spruce stands with known age.Results:The best modelling strategy was to fit independent linear regression models to each observed site index(SI)level and using a SI prediction map in the application of the models.The most important predictor variable was an upper percentile of the ALS heights,and root mean squared errors(RMSEs)ranged between 3 and 31 years(6%to 26%)for SI-specific models,and 21 years(25%)on average.Mean deviance(MD)ranged between^(−1) and 3 years.The models improved with increasing SI and the RMSEs were largest for low SI stands older than 100 years.Using a mapped SI,which is required for practical applications,RMSE and MD on plot level ranged from 19 to 56 years(29%to 53%),and 5 to 37 years(5%to 31%),respectively.For the validation stands,the RMSE and MD were 12(22%)and 2 years(3%),respectively.Conclusions:Tree height estimated from airborne laser scanning and predicted site index were the most important variables in the models describing age.Overall,we obtained good results,especially for stands with high SI.The models could be considered for practical applications,although we see considerable potential for improvements if better SI maps were available. 展开更多
关键词 forest age LIDAR Optical satellite images Remote sensing forest inventory
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Forest biomass carbon storage from multiple inventories over the past 30 years in Gansu Province, China: implications from the age structure of major forest types 被引量:5
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作者 Jinhong Guan Huanshui Zhou +2 位作者 Lei Deng Jianguo Zhang Sheng Du 《Journal of Forestry Research》 SCIE CAS CSCD 2015年第4期887-896,共10页
We used the forest inventory data of Gansu Province, China to quantify carbon storage and carbon density changes by regional forest cover and by typical forest types in 1979-2006. Total forest area increased from 1.77... We used the forest inventory data of Gansu Province, China to quantify carbon storage and carbon density changes by regional forest cover and by typical forest types in 1979-2006. Total forest area increased from 1.77 x 106 ha in 1979 to 2.32 x 106 ha in 2006, and the forest carbon storage, estimated by the continuous biomass expansion factor method, increased from 83.14 to 100.66 Tg, equivalent to a carbon accumulation rate of 0.0071 Tg per year during the period. Mean carbon densities were 44.83-48.50 t ha-1 and the values decreased slightly over the time period. Natural forests generated greater car- bon storage and density than did plantations. By regression analysis, forest stand age was an important parameter incarbon density studies. We developed various regression equations between carbon density and stand age for major types of natural forests and plantations in the region. Our results can be used for proper selection of re-forestation species and efficient management of young and middle-aged forests, offering great potential for future carbon sequestra- tion, especially in arid and semi-arid regions. 展开更多
关键词 age class Carbon density forest carbonstorage forest inventory data Gansu Province REforestATION
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Spatial distribution pattern of Picea schrenkiana population in the Middle Tianshan Mountains and the relationship with topographic attributes 被引量:12
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作者 YuTao ZHANG JiMei LI +2 位作者 ShunLi CHANG Xiang LI JianJiang LU 《Journal of Arid Land》 SCIE 2012年第4期457-468,共12页
The spatial distribution of plant populations is an important feature of population structure and it de- termines the population's ecological preferences, biological characteristics and relationships with environment... The spatial distribution of plant populations is an important feature of population structure and it de- termines the population's ecological preferences, biological characteristics and relationships with environmental factors. The point pattern analysis method was adopted to study the distribution pattern of Picea schrenkiana indi- viduals of different size classes and the correlations between two size classes as well as the impact of topog- raphical attributes on the population distribution. With increasing diameter at breast height, the plant density of the P. schrenkiana population showed a declining trend. Old trees showed a random distribution at a small spatial scale (0-12 m), whereas saplings, small trees and big trees all had an aggregated distribution at all scales. With the increase of tree age, the scales at which maximal aggregation occurred gradually increased and the aggregation strength decreased. At a small scale (0-16 m), all size classes showed a negative correlation and the larger the difference between tree size, the more significant the negative correlation. The number of medium, big and old trees had a significantly positive correlation with elevations, whereas the number of saplings and small trees was not significantly correlated with elevations. The numbers of saplings, small and medium trees showed a significant positive correlation with slope gradient, whereas the number of big trees was not significantly correlated, and the number of old trees was negatively correlated with gradient. With the exception of old trees, saplings, small, me- dium and big trees showed negative correlations with convexity index. The study provides a theoretical basis for the conservation, rehabilitation and sustainable management of forest ecosystems in the Tianshan Mountains. 展开更多
关键词 Picea schrenkiana coniferous forest population structure spatial correlation age class topographic attribute
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