1960-2009年西南地区极端干旱气候变化(英文)

Based on the daily data of temperature and precipitation of 108 meteorological stations in Southwest China from 1960 to 2009, we calculate the monthly and yearly surface humid indexes, as well as the extreme drought frequency. According to the data, the temporal and spatial characteristics of the extreme drought frequency in inter-annual, inter-decadal, summer monsoon period and winter monsoon period are analyzed. The results are indicated as follows. (1) In general, the southwestern Sichuan Basin, southern Hengduan Mountains, southern coast of Guangxi and northern Guizhou are the areas where the extreme drought frequency has significantly increased in the past 50 years. As for the decadal change, from the 1960s to the 1980s the extreme drought frequency has presented a decreasing trend, while the 1990s is the wettest decade and the whole area is turning wet. In the 2000s, the extreme drought frequency rises quickly, but the regional differences reduce. (2) During summer monsoon period, the extreme drought frequency is growing, which generally occurs in the high mountains around the Sichuan Basin, most parts of Guangxi and "the broom-shaped mountains" in Yunnan. It is distinct that the altitude has impacts on the ex-treme drought frequency; during winter monsoon period, the area is relatively wet and the extreme drought frequency is decreasing. (3) During summer monsoon period, the abrupt change is observed in 2003, whereas the abrupt change during winter monsoon period is in 1989. The annual extreme drought frequency variation is a superposition of abrupt changes during summer monsoon and winter monsoon periods. The departure sequence vibration of annual extreme drought frequency is quasi-5 years and quasi-12 years.     

Multi-scale temperature variations and their regional differences in China during the Medieval Climate Anomaly

The Medieval Climate Anomaly(MCA, AD950–1250) is the most recent warm period lasting for several hundred years and is regarded as a reference scenario when studying the impact of and adaptation to global and regional warming. In this study, we investigated the characteristics of temperature variations on decadal–centennial scales during the MCA for four regions(Northeast, Northwest, Central-east, and Tibetan Plateau) in China, based on high-resolution temperature reconstructions and related warm–cold records from historical documents. The ensemble empirical mode decomposition method is used to analyze the time series. The results showed that for China as a whole, the longest warm period during the last 2000 years occurred in the 10 th–13 th centuries, although there were multi-decadal cold intervals in the middle to late 12 th century. However, in the beginning and ending decades, warm peaks and phases on the decadal scale of the MCA for different regions were not consistent with each other. On the inter-decadal scale, regional temperature variations were similar from 950 to 1130; moreover, their amplitudes became smaller, and the phases did not agree well from 1130 to 1250. On the multi-decadal to centennial scale, all four regions began to warm in the early 10 th century and experienced two cold intervals during the MCA. However, the Northwest and Central-east China were in step with each other while the warm periods in the Northeast China and Tibetan Plateau ended about 40-50 years earlier. On the multi-centennial scale, the mean temperature difference between the MCA and Little Ice Age was significant in Northeast and Central-east China but not in the Northwest China and Tibetan Plateau. Compared to the mean temperature of the 20 th century, a comparable warmth in the MCA was found in the Central-east China, but there was a little cooling in Northeast China; meanwhile, there were significantly lower temperatures in Northwest China and Tibetan Plateau.     

Research for length change of four seasons over China in recent 47 years

Using daily temperature data from 599 Chinese weather stations during 1961–2007, the length change trends of four seasons during the past 47 years were analyzed. Results show that throughout the region, four seasons’ lengths are: spring becomes shorter (-0.8 d/10yrs), summer becomes longer (3.2 d/10yrs), autumn (-0.5 d/10yrs) and winter (-1.6 d/10yrs) becomes shorter. This trend is different in spatial distribution, namely it is very obvious in northern than southern China, and also remarkable in eastern than western China. Summer change is most obvious, but autumn has little change comparatively. This trend is highly obvious in North, East, Central and South China. In the Southwest starting in the 21st century, summer becomes longer and winter shortens. The trend in the Plateau region since the 1980s is that spring becomes longer and winter shortens. The average annual temperature increased during the past 47 years, and the change of the average annual temperature precedes seasons’ length. Thus, the average annual temperature has a certain influence on the length change of seasons.     

1736–2010年华南前汛期始日变化(英文)

The starting dates of the pre-summer rainy season during historical times(1736– 1911) in Fuzhou and Guangzhou of South China, were determined and reconstructed on the basis of historical documents in the Yu-Xue-Fen-Cun archive, together with observed features of precipitation during the pre-summer rainy season. In addition, starting dates of the pre-summer rainy season from 1953 in Fuzhou and from 1952 in Guangzhou were reconstructed for the instrumental period. These data allowed for analyses of inter-annual and inter-decadal changes in the starting dates of the pre-summer rainy season in South China over the past 300 years. Results show that the mean starting date of the pre-summer rainy season in South China was the first pentad of May; in addition, periodicities in the starting dates of 2–3 years, 10 years, and 40 years were detected during the period 1736–1911, and of 2–3 years, 10 years, and 22 years during the instrumental period. From 1736 to 1911, the earliest starting dates at Fuzhou and Guangzhou both occurred at the fourth pentad of April, while the latest starting dates were at the sixth pentad of May in Fuzhou and the first pentad of June in Guangzhou. During the instrumental period, the earliest and latest starting dates were at the fourth pentad of April and the first pentad of June, respectively, in both Fuzhou during 1953–2010 and Guangzhou during 1952–2010. The maximum difference between neighboring decades during 1736–1911 was 2.2 and 1.6 pentads in Fuzhou and Guangzhou, respectively, and during the instrumental period it was 2.5 and 2.4 pentads in Fuzhou and Guangzhou, respectively.     

Variations in the starting date of the pre-summer rainy season in South China, 1736–2010

The starting dates of the pre-summer rainy season during historical times （1736- 1911） in Fuzhou and Guangzhou of South China, were determined and reconstructed on the basis of historical documents in the Yu-Xue-Fen-Cun archive, together with observed features of precipitation during the pre-summer rainy season. In addition, starting dates of the pre-summer rainy season from 1953 in Fuzhou and from 1952 in Guangzhou were reconstructed for the instrumental period. These data allowed for analyses of inter-annual and inter-decadal changes in the starting dates of the pre-summer rainy season in South China over the past 300 years. Results show that the mean starting date of the pre-summer rainy season in South China was the first pentad of May; in addition, periodicities in the starting dates of 2-3 years, 10 years, and 40 years were detected during the period 1736-1911, and of 2-3 years, 10 years, and 22 years during the instrumental period. From 1736 to 1911, the earliest starting dates at Fuzhou and Guangzhou both occurred at the fourth pentad of April, while the latest starting dates were at the sixth pentad of May in Fuzhou and the first pentad of June in Guangzhou. During the instrumental period, the earliest and latest starting dates were at the fourth pentad of April and the first pentad of June, respectively, in both Fuzhou during 1953-2010 and Guangzhou during 1952-2010. The maximum difference between neighboring decades during 1736-1911 was 2.2 and 1.6 pentads in Fuzhou and Guangzhou, respectively, and during the instrumental period it was 2.5 and 2.4 pentads in Fuzhou and Guangzhou, respectively.     

Trends in precipitation over the low latitude highlands of Yunnan, China

The precipitation regime of the low latitude highlands of Yunnan in Southwest China is subject to the interactions between the East Asian Summer Monsoon and the Indian Summer Monsoon, and the influence of surface orography. An understanding of changes in its spatial and temporal patterns is urgently needed for climate change projection, hydrologi- cal impact modelling, and regional and downstream water resources management. Using daily precipitation records of the low latitude highlands over the last several decades （1950s-2007）, a time series of precipitation indices, including annual precipitation, number of rainy days, mean annual precipitation intensity, the dates of the onset of the rainy season, degree and period of precipitation seasonal concentration, the highest 1-day, 3-day and 7-day precipitation, and precipitation amount and number of rainy days for precipitation above dif- ferent intensities （such as 〉~10 mm, 〉~25 mm and 〉~50 mm of daily precipitation）, was con- structed. The Trend-Free Pre-Whitening Mann-Kendall trend test was then used to detect trends of the time series data. The results show that there is no significant trend in annual precipitation and strong seasonal differentiation of precipitation trends across the low latitude highlands. Springs and winters are getting wetter and summers are getting drier. Autumns are getting drier in the east and wetter in the west. As a consequence, the seasonality of pre- cipitation is weakening slightly. The beginning of the rainy season and the period of the highest precipitation tend to be earlier. In the meantime, the low latitude highlands has also witnessed less rainy days, more intense precipitation, slightly longer moderate and heavy precipitation events, and more frequent extreme precipitation events. Additionally, regional differentiation of precipitation trends is remarkable. These variations may be associated with weakening of the East Asian summer monsoon and strengthening of the South Asian summer monsoon, as well as the ＂corridor-barrier＂ effects of special mountainous terrain. However, the physical mechanisms involved still need to be uncovered in the future.     

Wavelet analysis of quasi-3-year temperature oscillations in China in last 50 years, and predicted changes in the next 20 years

The wavelet analysis method is used to analyze the annual and winter temperature data of 98 observation stations in China in eight climate zones during the last 50 years （1961-2009）. The periodicities of temperature changes are investigated, and the possible temperature change trends in China in the next 20 years （2012-2029） are also predicted. Our results show that in the inter-annual temperature variability there are pervasive quasi-3- to quasi-4-year cycles, and these cycle changes are relatively steady. The periodic characteristics of the annual temperature changes are clearly different between northern and southern China, and our period superimposition extrapolation shows that both annual and winter temperatures in China will continue to increase in the next 20 years, more so in northern China and in the Qinghai-Xizang Plateau （QXP） than in the southern region, except in the southwest. If temperatures follow historic increasing linear trends, the overall temper- ature is expected to increase by 1℃ between 2010 and 2029.     

1960-2015年中国绿洲胡杨生长季对全球变暖的时空响应及原因（英文）

Daily average temperature data from 48 meteorological stations in Chinese oases that are within the distribution area of Populus euphratica were analyzed to determine the spatiotemporal responses of this tree to climate change. Specifically, the start and end date as well as the number of days that comprised the growing season were analyzed with a multi-year trend line and using the Mann-Kendall mutation test, inverse distance weighted interpolation(IDW) in the software Arc GIS, a Morlet wavelet power spectrum, and correlation analysis. The results of this study show that, over the last 56 years, the start date of the P. euphratica growing season has advanced, while the end date has been postponed, and the number of days that comprise the growing season have gradually increased. The changing trend rates recovered in this analysis for these three time slices are –1.34 d/10 a, 1.33 d/10 a, and 2.66 d/10 a(α≥ 0.001), respectively. Data show that while spatial disparity is extremely significant, it is nevertheless the case that along a southwest-to-northeast transect of Chinese oases, the later the start date of the P. euphratica season, the sooner the end data and the shorter the growing season. Mutations points in start and end date, as well as for the growing season overall were observed in 2001, 1989, and 1996, respectively, and the data presented in this paper show that, in particular, the date of this end of this period is most sensitive to climate warming. Growing season cycles for P. euphratica are between 3.56 years and 7.14 years, consistent with the periodicity of El Ni?o events, while a start date cycle between 3.56 years and 4.28 years is consistent with atmospheric circulation cyclicity. The causal analysis presented in this paper shows that the Asian polar vortex area index(APVAI), the Qinghai-Tibet Plateau index(TPI), the westerly circulation index(WCI), and carbon dioxide emissions(CDE) are the main factors influencing spatiotemporal changes in the growth of P. euphratica, the effect of latitude during the growing season is more significant than altitude, and the start date of the growing season is more significantly influenced by these factors than end date. In addition, data show that the start date, end date, and length of the growing season are all significantly correlated with their average corresponding monthly temperature(corre-lation coefficients are –0.875, 0.770, and 0.897; α≥0.001). Thus, if the average temperature in March increases by 1℃, the start date of the growing season will advance by 2.21 days, while if the average temperature in October increases by the same margin then the seasonal end date will be delayed by 2.76 days. Similarly, if the average temperature between March and October increases by 1℃, the growing season will be extended by 7.78 days. The results of this study corroborate the fact that changes in the P. euphratica growing are sensitive to regional warming and are thus of considerable theoretical significance to our understanding of the responses of Chinese vegetation to climate change as well as to ecological restoration.     

Progress in China’s climate change study in the 20th century

IPCC (2001) pointed out that the earth's climate was undergoing a remarkable change with characteristics of global warming over the past 100 years. The latest research showed that the global mean surface temperature has increased by about 0.6 oC since 1861. It is very likely that the last 20 years in the 20th century was the warmest decades. The Northern Hemisphere temperatures in the 20th century appeared to have been unprecedented during the past millennium. The research also indicates th…     

Precipitation cycles in the middle and lower reaches of the Yellow River （1736-2000）

Based on the long-term precipitation series with annual time resolution in the middle and lower reaches of the Yellow River and its four sub-regions during 1736-2000 reconstructed from the rainfall and snowfall archives of the Qing Dynasty, the precipitation cycles are analyzed by wavelet analysis and the possible climate forcings, which drive the precipitation changes, are explored. The results show that： the precipitation in the middle and lower reaches of the Yellow River has inter-annual and inter-decadal oscillations like 2-4a, quasi-22a and 70-80a. The 2-4a cycle is linked with El Nino events, and the precipitation is lower than normal year in the occurrence of the El Nino year or the next year; for the quasi-22a and the 70-80a cycles, Wolf Sun Spot Numbers and Pacific Decadal Oscillation （PDO） coincide with the two cycle signals. However, on a 70-80a time scale, the coincidence between solar activity and precipitation is identified before 1830, and strong （weak） solar activity is generally correlated to the dry （wet） periods; after 1830, the solar activity changes to 80-100a quasi-century long oscillation, and the adjusting action to the precipitation is becoming weaker and weaker; the coincidence between PDO and precipitation is shown in the whole time series. Moreover, in recent 100 years, PDO is becoming a pace-maker of the precipitation on the 70-80a time scale.     

Climate change inferred from aeolian sediments in a lake shore environment in the central Tibetan Plateau during recent centuries

Studies of the past climate variation on the Tibetan Plateau(TP) are currently limited in number and low in density and temporal resolution. We investigated the climate condition from about 400 years before present(B.P.) in the central TP at the shore of Co(means "lake") Nag using aeolian sediments. A 2.7-m sand profile with 57 sediment samples and six optically stimulated luminescence(OSL) samples were studied through grain-size analysis, geochemical elements and parameters, and depositional rate estimation. A previous assumption was verified that sand deposition at the shore of Lake Co Nag originated from hills to the east. Two significant wet periods between 90–140 and about 380 years B.P. were indicated by the variation of element profiles and sediment depositional rates. Aeolian activity is sensitive to variations from different seasonal changing patterns of climate factors in the study area, and aeolian sediments respond differently to climate conditions during the cold little ice age(LIA) and the warm 20 th century. Present day dry seasons of winter and spring might be much warmer and drier compared to seasons of 400 years ago although summer precipitation has increased, resulting in significantly more aeolian activity and higher depositional rate(about 6 times compared to 380–240 years ago) of sandy sediments. Aeolian problems like blown-sand deposition and desertification may be worse in a projected warming future in the central TP as well as other cold and high altitude regions. Our results suggest an agreement with environmental evolution during the little ice age and the 20 th century in a broader scale on the TP.     

中国近代北方极端干湿事件的演变规律

Using monthly precipitation and monthly mean temperature, a surface humid index was proposed. According to the index, the distributed characteristics of extreme dryness has been fully analyzed. The results indicated that there is an obvious increasing trend of extreme dryness in the central part of northern China and northeastern China in the last 10 years, which shows a high frequency period of extreme dryness; while a low frequency period in the regions during the last 100 years. Compared with variation trend of the temperature in these regions, the region of high frequent extreme dryness is consistent with the warming trend in the same region.     

1956-2000年云南红河流域径流的时空分布

This paper studies the variation of runoff of Red River Basin and discusses the influence of＂corridor-barrier＂functions of valleys and mountains on variation of runoff by using GIS and statistic methods based on the monthly precipitation,temperature and evaporation data from 1960 to 2000 at 32 meteorological stations in Red River Basin,and the annual runoff data of Yuanjiang River,Lixian River and Panlong River from 1956 to 2000.The results show out：（1）Under the effect of＂corridor-barrier＂functions of valleys and mountains in Red River Basin,the patterns of annual precipitation and runoff depth distribution in spatial change a NW-SE direction,which is similar with the trend of the Red River valley and Ailao mountains.（2）In the long temporal scale averaged over years,the most obvious effects of the＂corridor-barrier＂functions is on runoff variation,and the second is on the precipitation, but not obvious on the temperature.（3）Under the superposed effect of climate changes and the＂corridor-barrier＂functions of valleys and mountains in Red River Basin,the difference of runoff variation is obvious in the east-west direction：the runoff variation of Yuanjiang River along the Red River Fault present an ascending trend,but the Lixian River on the west side of the Fault and the Panlong River on the east present a descending trend;the annual runoff in Yuanjiang River and Panlong River had a quasi-5a periods,and Panlong River had a quasi-8a periods;the runoff variation are quite inconsistent in different periods among the three river basins.     

1901–2013年中亚季节降水时空变化特征及其与ENSO的关系（英文）

The vulnerable ecosystem of the arid and semiarid region in Central Asia is sensitive to precipitation variations. Long-term changes of the seasonal precipitation can reveal the evolution rules of the precipitation climate. Therefore, in this study, the changes of the seasonal precipitation over Central Asia have been analyzed during the last century(1901–2013) based on the latest global monthly precipitation dataset Global Precipitation Climatology Centre(GPCC) Full Data Reanalysis Version 7, as well as their relations with El Ni?oSouthern Oscillation(ENSO). Results show that the precipitation in Central Asia is mainly concentrated in spring and summer seasons, especially in spring. For the whole study period, increasing trends were found in spring and winter, while decreasing trends were detected in summer and fall. Inter-annual signals with 3–7 years multi-periods were derived to explain the dominant components for seasonal precipitation variability. In terms of the dominant spatial pattern, Empirical orthogonal function(EOF) results show that the spatial distribution of EOF-1 mode in summer is different from those of the other seasons during 1901–2013. Moreover, significant ENSO-associated changes in precipitation are evident during the fall, winter, spring, and absent during summer. The lagged associations between ENSO and seasonal precipitation are also obtained in Central Asia. The ENSO-based composite analyses show that these water vapor fluxes of spring, fall and winter precipitation are mainly generated in Indian and North Atlantic Oceans during El Ni?o. The enhanced westerlies strengthen the western water vapor path for Central Asia, thereby causing a rainy winter.     

基于方志资料重建1644-1949年长江三角洲地区台风频次序列(英文)

The proxy records on typhoons in the Yangtze River Delta from 1644 to 1949AD were extracted from historical chorographies in the Qing Dynasty and the Republic of China Period.In reference to the basic principles for identifying historical typhoons,time series on the Yangtze River Delta over a period of 306 years were developed.The conclusions are as follows.(1) There were a total of 241 typhoons from 1644 to 1949AD.Using the historical chorographies from 1884 to 1949AD,the number of typhoons was 65,equal to 87.8% recorded by meteorological observation.The number of years with differences in typhoon activities reconstructed using two ways no more than once is 55,reaching 83.3% in the period from 1884 to 1949AD.This result means the series of historical typhoons reconstructed using historical chorographies can represent the change of typhoon activities over years.(2) The average number of typhoon activities is 0.79 times per year from 1644 to 1949AD,and they show an increasing trend.These 306 years can be divided into three periods by the average number of typhoon activities:it is low from 1644 to 1784AD,and more typhoon activities are found from 1785 to 1904AD.It is worth noting that the number of typhoon activities reaches the summit in the last period,which is 1.2 times per year from 1905 to 1949AD.(3) Before the 20th century,the number of typhoon activities in warm periods is less than the number of cold periods.However,the number of typhoon activities increased dramatically in the early 20th century.Comparing the typhoon activities with El Ni o events,the data show that the number of typhoon activities did not increase when El Ni o occurred.     

Spatial and temporal distribution of storms and their activities over the Bay of Bengal

By statistically analyzing the storm data from the Joint Typhoon Warning Center(JTWC) over the Bengal Bay during the period 1945-2006,it is found that the yearly averaged tropical cyclone(TC) number over the Bay of Bengal is 8.12,which takes place in any month of the whole year;February and March have the fewest TC numbers.The TC numbers begin to increase starting in April and arrive at a peak in October.Differing from TC over the Bay of Bengal,the tropical storms(TS) over the Bay of Bengal has two peak periods,appear in May and in October or November,respectively.With regard to TS intensity,the super severe storm of H4 criterion appeared only one time during the period 1971-1986,but appeared eight times during the period 1987-2006.The monthly change of the original position,the averaged maintaining time,and the longest maintaining time of TS also have two peak values:They appear in April or May and in October or November,respectively.The peak value of the original position in October or November is bigger than that in April or May.The peak value of the average maintaining time and the longest main-taining time of the TS in April or May is bigger than that in October or November.TC landfall path is mostly moving toward northwest or west and accounts for 56.7 percent.The landfall path of the TS differs from that of TC in some respects.The main difference is that the numbers of the northwestern path and un-landfall of TS are less than those for TC,and the numbers of the western path and northeastern path of TS are greater than for TC.Because of the landfall TS in the north-east path has a peak,it and the beginning of the rainy season in Yunnan Province are closely related;it is on Yunnan Province’s early summer precipita-tion that they have a great impact.     

1981–2010年中国散射光合有效辐射的估算及时空特征(英文)

Photosynthetically active radiation(PAR) is the energy source of plant photosynthesis, and the diffuse component can enhance canopy light use efficiency, thereby increasing the carbon uptake. Therefore, diffuse PAR is an important driving factor of ecosystem productivity models. In this study, we estimated the diffuse PAR of over 700 meteorological sites in China from 1981 to 2010 using an empirical model based on observational data from Chinese Ecosystem Research Network(CERN) and China Meteorology Administration. Then we derived the spatial data set of 10 km monthly diffuse PAR using ANUSPLIN software, and analyzed the spatiotemporal variation characteristics of diffuse PAR through GIS and trend analysis techniques. The results showed that:(1) The spatial patterns of annual average diffuse PAR during 1981–2010 are heterogeneous across China, lower in the northeast and higher in the west and south. The nationwide average value for 30 years ranges from 6.66 mol m-2 d-1 to 15.27 mol m-2 d-1, and the value in summer is the biggest while the value in winter is the smallest.(2) There is an evident increasing trend of annual diffuse PAR during recent 30 years, with the increasing amplitude at 0.03 mol m-2 d-1/10a. But a significant declining trend is shown in the first 10 years, and obvious anomalies can be seen in 1982, 1983, 1991 and 1992. And there is a downtrend in spring and an uptrend in all the other seasons.(3) The spatial distribution of temporal variation rates of diffuse PAR is inhomogeneous across the country, generally decreasing in the north and increasing in the south.     

Variations in spring leaf phenology and leaf freezing damage of common woody species in China北大核心CSCD

Freezing damage results in the dehydration of plant cells and reduces the photosynthetic capacity of plants, which causes significant losses to ecology and economy. Over the past 40 years, global warming has reduced the frequency and intensity of frost events while bringing forward the spring phenology of plants, increasing the exposure of their leaves and flowers to harsh cold temperatures. Therefore, the dual effects of climate warming should be considered in order to accurately assess the changes of plant freezing damage. To date, there is no systematic analysis of plant freezing damage in different climatic regions of China. Based on phenological observation records from the China Phenological Observation Network, leaf frost damage of four common woody plants (Ulmus pumila, Robinia pseudoacacia, Salix babylonica, Fraxinus chinensis) in the spring over the past 40 years was calculated, and the spatio-temporal patterns were analyzed. We also investigated the change in the occurrence time of maximum frost damage (TMFD) and its relationship with plant phenology. The results show that: 1) Most species presented an overall trend towards an earlier leaf unfolding date, and the advancing trend was significant and greater than 1 d/a in about 60% of the regions (P<0.05). 2) The TMFD occurred earlier in 72.22%-83.03% of the regions, which was closely related to plants' earlier leaf unfolding date. The TMFD of all species advanced the most (8.3 days) in the temperate climate zone, followed by the warm temperate, subtropical, plateau, and cold temperate zones. 3) The leaves of U. pumila, R. pseudoacacia and S. babylonica suffered more freezing damage in the spring, and the most significant freezing damage was mainly found in the north of 50°N region and part of the west of the Qinghai-Tibet Plateau. In comparison, the leaves of F. chinensis suffered less frost damage due to later leaf unfolding date and stronger leaf frost resistance. With regard to interannual variations, the average freezing damage of U. pumila, R. pseudoacacia and S. babylonica increased significantly (P<0.05), but that of F. chinensis did not change obviously. In addition, the freezing damage of U. pumila and S. babylonica increased the most in the cold temperate zone, while that of R. pseudoacacia increased in about 10% of the regions in the plateau climate zone, and 3%-6% of the regions in the cold temperate, temperate, and warm temperate climate zones. The freezing damage of F. chinensis merely increased in the warm temperate zone. The results of this study can provide a reference for assessing the risk of plant freezing damage accurately and help develop regional-specific response and adaptation strategies to climate change. © 2023, Editorial office of PROGRESS IN GEOGRAPHY. All rights reserved.     

黑河流域气候变化对水资源的影响

1IntroductionThe climate conditions of temperature and precipitation are of primary importance for arid region and a change of climate in the direction to warmer or colder, wetter or drier would have large water resources, biological and socio-economic consequences (Raino Heino, 1994; Guido V etal., 2001).Since last century, there has been a warming trend for global climate with greenhouse gases such as CO2 continually increasing. The trend got intensified particularly in the late 20th centu…     

300年来中国森林的变化

Based on historical documents, modern survey and statistics, as well as the result of predecessor studies, the trend and main process of forest dynamics are recognized. The forest area and forest coverage rates for each province of China from 1700 to 1949 are estimated backward by every 50 years. Linking the result with modern National Forest Inventory data, the spatial-temporal dynamics of Chinese forest in recent 300 years （AD 1700-1998） is quantitatively analyzed. The study shows that in recent 300 years, the forest area in current territory of China has declined by 0.95×10^8 hm^2 （or 9.2% of the coverage rate） in total, with a trend of decrease and recovery. Before the 1960s, there was a trend of accelerated descending. The forest area was reduced by 1.66×10^8 hm^2 （or 17% of the coverage rate） in 260 years. While after the 1960s, there has been a rapid increase. The forest area increased by 0.7×10^8 hm^2 （or 8% of the coverage rate） in 40 years. The study also shows that there is a significant spatial difference in the dynamics of forest. The amplitudes of increasing and decreasing in western China are both smaller than the ones in eastern China. During the rapid declining period from 1700 to 1949, the most serious decrease appeared in the Northeast, the Southwest and the Southeast, where the coverage rate in most provinces dropped over 20%. In Heilongjiang Province, the coverage rate dropped by 50%. In Jilin Province, it dropped by 36%. In Sichuan Province and Chongqing Municipality, it dropped by 42%. In Yunnan Province, it dropped by 35%. During the recovery period 1949-1998, the western provinces, municipality and autonomous regions, including Ningxia, Gansu, Inner Mongolia, Sichuan-Chongqing, Yunnan, Tibet, Xinjiang and Qinghai, etc, the increase rates are all below 5%, while the eastern provinces, municipality and autonomous regions （except Heilongjiang, Hubei, Jiangsu-Shanghai） have achieved an increase over 5%, among which the Guangdong-Hainan, Guangxi, Anhui, Beijing-Tianjin-H