Differential response of radial growth and δ^(13)C in Qinghai spruce(Picea crassifolia) to climate change on the southern and northern slopes of the Qilian Mountains in Northwest China

Tree radial growth can have significantly differ-ent responses to climate change depending on the environ-ment.To elucidate the effects of climate on radial growth and stable carbon isotope(δ^(13)C)fractionation of Qing-hai spruce(Picea crassifolia),a widely distributed native conifer in northwestern China in different environments,we developed chronologies for tree-ring widths and δ^(13)C in trees on the southern and northern slopes of the Qilian Mountains,and analysed the relationship between these tree-ring variables and major climatic factors.Tree-ring widths were strongly influenced by climatic factors early in the growing season,and the radial growth in trees on the northern slopes was more sensitive to climate than in trees on the southern.Tree-ring δ^(13)C was more sensitive to climate than radial growth.δ^(13)C fractionation was mainly influenced by summer temperature and precipitation early in the growing season.Stomatal conductance more strongly limited stable carbon isotope fractionation in tree rings than photosynthetic rate did.The response between tree rings and climate in mountains gradually weakened as climate warmed.Changes in radial growth and stable carbon isotope fractionation of P.crassifolia in response to climate in the Qilian Mountains may be further complicated by continued climate change.

1991-2020 climate normal in the European Alps:focus on high-elevation environments

Alps are an important geographical area of the European continent and,in this area,temperature increase is most evident.However,the 1991-2020 climate normal in the Alps has still not been thoroughly investigated.Aiming to fill this gap with a focus on high-elevation environments,minimum and maximum daily air temperature acquired by 23 automatic weather station were used.The results show that the mean annual values of minimum and maximum temperature for the 1991-2020 climate normal in the Alps are-2.4℃ and 4.4℃,respectively,with a warming rate of 0.5℃/10 years.The mean annual temperature comparison between 1961-1990 and 1971-2000,1961-1990 and 1981-2010,1961-1990 and 1991-2020 climate normal show an increase of 0.3℃,0.5℃ and 0.9℃,respectively.The results also confirm that seasonal and annual temperatures are rising through the whole Alpine arc,mainly in summer and autumn.This work highlights that annual minimum and maximum temperature do not seem to be affected by a positive elevation-dependent warming.Instead,a positive elevation-dependent warming in the maximum values of the annual minimum temperature was found.If anthropogenic emissions maintain the trend of the last decades,the expected mean annual temperature of the 2001-2030 climate normal is-0.2℃,with an increase of 0.5℃ if compared to the 1991-2020 climate normal and with an increase of 1.5℃ if compared to the 1961-1990 climate normal.This study highlights the warming rate that is now present in the European Alps,provides indications on the warming rate that will occur in the coming years and highlights the importance of carrying out investigations that consider not only the last 30-year climate normal,but also the most recent 30-year climate normal by comparing them with each other.

Spatial variability of glacial changes and their effects on water resources in the Chinese Tianshan Mountains during the last five decades

Changes in glaciers in the Chinese Tianshan Mountains have been analyzed previously. However, most previous studies focused on individual glaciers and/or decentralized glacial basins. Moreover, a majority of these studies were published only in Chinese, which limited their usefulness at the international level. With this in mind, the authors reviewed the previous studies to create an overview of glacial changes in the Chinese Tianshan Mountains over the last five decades and discussed the effects of glacial changes on water resources. In response to climate change, glaciers in the Tianshan Mountains are shrinking rapidly and are ca. 20% smaller on average in the past five decades. Overall, the area reduction of glacial basins in the central part of the Chinese Tianshan Mountains is larger than that in the eastern and western parts. The spatial differentiation in glacial changes are caused by both differences in regional climate and in glacial factors. The effects of glacial changes on water resources vary in different river basins due to the differences in glacier distribution, characteristics of glacial change and proportion of the glacier meltwater in river runoff.

Comparison of the spatio-temporal dynamics of vegetation between the Changbai Mountains of eastern Eurasia and the Appalachian Mountains of eastern North America

The Changbai Mountains and the Appalachian Mountains have similar spatial contexts.The elevation,latitude,and moisture gradients of both mountain ranges offer regional insight for investigating the vegetation dynamics in eastern Eurasia and eastern North America.We determined and compared the spatial patterns and temporal trends in the normalized difference vegetation index(NDVI)in the Changbai Mountains and the Appalachian Mountains using time series data from the Global Inventory Modeling and Mapping Studies 3^(rd) generation dataset from 1982 to 2013.The spatial pattern of NDVI in the Changbai Mountains exhibited fragmentation,whereas NDVI in the Appalachian Mountains decreased from south to north.The vegetation dynamics in the Changbai Mountains had an insignificant trend at the regional scale,whereas the dynamics in the Appalachian Mountains had a significant increasing trend.NDVI increased in 55% of the area of the Changbai Mountains and in 95% of the area of the Appalachian Mountains.The peak NDVI occurred one month later in the Changbai Mountains than in the Appalachian Mountains.The results revealed a significant increase in NDVI in autumn in both mountain ranges.The climatic trend in the Changbai Mountains included warming and decreased precipitation,and whereas that in the Appalachian Mountains included significant warming and increased precipitation.Positive and negative correlations existed between NDVI and temperature and precipitation,respectively,in both mountain ranges.Particularly,the spring temperature and NDVI exhibited a significant positive correlation in both mountain ranges.The results of this study suggest that human actives caused the differences in the spatial patterns of NDVI and that various characteristics of climate change and intensity of human actives dominated the differences in the NDVI trends between the Changbai Mountains and the Appalachian Mountains.Additionally,the vegetation dynamics of both mountain ranges were not identical to those in previous broader-scale studies.

Temporal and spatial variations in extreme temperatures in the Qilian Mountains-Hexi Corridor over the period 1960-2013

Based on daily maximum and minimum temperatures at 18 meteorological stations in the Qilian Mountains and Hexi Corridor between 1960 and 2013,temporal and spatial variations in extreme temperatures were analysed using linear trends,tenpoint moving averages and the Mann-Kendall test.The results are as follows:The trends in the majority of the extreme temperature indices were statistically significant,and the changes in the extreme temperatures were more obvious than the changes in the extreme values.The trends were different for each season,and the changes in rates and intensities in summer and autumn were larger than those in spring and winter.Unlike the cold indices,the magnitudes and trends of the changes in the warm indices were larger and more significant in the Hexi Corridor than in the Qilian Mountains.Abrupt changes were detected in the majority of the extreme temperature indices,and the extreme cold indices usually occurred earlier than the changes in the extreme warm indices.The abrupt changes in the extreme temperatures in winter were the earliest among the four seasons,indicating that these temperature changes were the most sensitive to global climate change.The timing of the abrupt changes in certain indices was consistent throughout the study area,but the changes in the cold indices in the Hexi Corridor occurred approximately four years before those in the Qilian Mountains.Similarly,the changes in the warm indices in the western Hexi Corridor preceded those of the other regions.

THE CLIMATIC STUDY OF CHANGBAI MOUNTAIN BY INTEGRATION OF REMOTE SENSING INFORMATION AND GEO-CODED IMAGES

Ⅰ. INTRODUCTION Changbai Mountain is situated between E127°54′-128°08′, N40°58′-42°06′ about 2700 meters above sea level. It is the typical area of the mountainous climate in the monsoon area of the temperate zone on the globe. The well reserved primeval vertical distribution of natural landscape belts and the Natural Conservation of Changbai Mountains adopted by the UNESCO′s MAB Program cause the worldwide attention of geographers. Beside the complexity of the climatic structure itself, the mechanical effection of the high mountain body also effect the climate in the eastern part of China. In the mountain area where short of meteorological observation data, the climatic study by remote sensing is favorable for discovery and representation of climatic law in large area.

Evolution of temperature indices in the periglacial environment of the European Alps in the period 1990-2019

Air temperature in the European Alps shows warming over recent decades at an average rate of 0.3℃/10 years,therebyoutpacing the global warming rate of 0.2℃/10 years.The periglacial environment of the Alps is particularly important for several aspects(i.e.hydropower production,tourism,natural hazards,indicator of global warming).However,there is a lack of specific and updated studies relating to temperature change in this environment.In order to fill this gap,the recent temperature trends in the periglacial environment of the Alps were analyzed.Mean/maximum/minimum daily air temperatures recorded by 14 land-based meteorological stations were used,and the temperature indices for the period 1990-2019 were calculated.The periglacial environment of the Alps showed a warming rate of 0.4℃/10 years,0.6℃/10 years and 0.8℃/10 years for the mean/maximum/minimum temperatures,respectively.These warming rates are higher than that observed for the entire Alpine area.In 2050 many glaciers of the Alps below 3000 m altitude are expected to be extinct,and all the areas previously occupied by glaciers will become periglacial.In order to manage and adapt to these changes,more in-depth climate analyses are needed.This is necessary for all the mountainous areas of the world,which are undergoing similar changes.

THE NUMERICAL SIMULATION OF TWO-DIMENSIONAL DYNAMICAL CLIMATE MODEL WITH MOUNTAIN FORCING

In order to investigate the effects of trace gases on climate variation in the atmosphere, we have devel- oped a primitive equation two-dimensional dynamical climate model with five levels. A series of simula- tion results and discussions are shown in this paper, indicating that the model is useful and can correctly reproduced the main feature of the general atmospheric circulation and its seasonal changes. In addition, we have discussed the role of the Qinghai-Xizang Plateau on the formation process of summer monsoon in South Asia and found that the thermal effect of the Qjnghai-Xizang Plateau may not be the main factor controlling the onset and the variation of the summer monsoon in South Asia.

Mixed signals in trends of variance in high-elevation tree ring chronologies

Increases in climate variability, including extremes, may be expected with anthropogenic climate change, but some evidence is contrary. The issue is important because the consequences of variability can be critical for ecosystems. It has long been known and often rehearsed that ecological consequences of increased variability may be greater than those that result from expected changes in mean temperature and precipitation. Tree rings have been useful indicators of ecological response to climate change and used as proxies for climate variability;work in the Rocky Mountains, USA, has been particularly informative. Chronologies from two high elevation species ranging over 2500 km were analyzed for changes in variance through time. These spatially extensive and disaggregated tree ring records do not show a consistent pattern of change in variance over the past 500 or 100 years; heteroscedasticity has recently been greater. A lack of consistent response in growth over a period encompassing changes in mean climate indicates that mountain environments, with inconsistent trends in temperature and precipitation,may be too complex to act as sentinels.

SIMULATION OF THE SPATIAL DISTRIBUTION OF CLIMATIC ELEMENTS IN MOUNTAINOUS REGIONS

In this paper,an effective method of simulating the spatial distribution of climatic elements in mountainous areas by using the semi-empirical theory is presented.As an example,the spatial distributions of temperature, vapor pressure,relative humidity,wind speed and precipitation in the Jianyang region and the Shaxi basin of Fujian Province are computed with this method,and the simulated results are in good agreement with the observations.