气候变化对呼伦贝尔草原生态环境的影响

浅析了气候变化对呼伦贝尔生态环境的影响效应,转型期气候对呼伦贝尔草原生态环境的严重威胁,以及生态环境发生变化和不合理人类活动的干扰;分析了引起草原植被退化、土层风蚀损失、沙漠化速度加快而失去平衡等的原因。

Social impacts of the climatic shift around the turn of the 19th century on the North China Plain

Historical case studies of climate change impacts and the resulting social responses can provide analogies for better under- standing the impacts of current and future climate changes. Around the turn of the 19th century, the climate of the North China Plain experienced a shift from a relatively warm stage in the 18th century to a colder stage in the 19th century, which was characterised by a much colder climate and more frequent and severe floods and droughts. Historical information about refu- gees, social disorder, grain transportation, and disaster relief on the North China Plain in 1780-1819 is collected from the Ver- itable Records of the Qing Dynasty （a collection of official records）. The mechanism of climate change affecting the food se- curity of the society, as indicated by the development of a refugee problem around the turn of the 19th century, is analyzed by examining the social vulnerability. There are four basic findings： （1） In the 40 years from 1780-1819, the society on the North China Plain was unstable and characterised by a significant deterioration of the refugee situation. The number of refugees in- creased markedly, and their behaviour became increasingly violent. In the 1780s, most of the disaster victims chose to stay at their residences waiting for relief. From 1790 to 1800, hundreds of thousands of refugees migrated to northeast China. In the 1810s, the frequency of farmer rebellions increased sharply. （2） The increase in instability corresponded to the climatic cooling over the same time period. The increased instability was a result of the negative impacts of climate change accumulating and transmitting to the social level. （3） For food security, a precondition for the negative impacts of climate change on human soci- ety was the vulnerability of the regional socioeconomic system, which had a high sensitivity and low capacity to respond. This vulnerability could be described by the following three observations： O The regional balance of supply and demand for food was in a critical state, which led to a high sensitivity and dramatic reduction in yield that was caused by climate change; （~ the capacity for disaster relief efforts by the government was too low to meet the needs of crisis management; （~ the capacity for refugees＇ resettlement in eastern Inner Mongolia and northeast China, which both border the North China Plain, was se- verely restricted by climatic conditions or the quarantine policy. （4） It is estimated that climate change caused the social vul- nerability to reach a critical level approximately 20 years earlier on the North China Plain.

Recent greening of grasslands in northern China driven by increasing precipitation

Aims Recent warmer and wetter climate in northern China remains a hot topic in recent years,yet its effect on vegetation growth has not been fully understood.This study investigated the temporal change of vegetation cover and its correlations with climatic variables from 1982 to 2018 for grasslands in northern China.Our aim is to clarify whether the warmer and wetter climate in recent years drives the greening of the vegetation in this region.Methods We investigated the temporal dynamic of vegetation normalized difference vegetation index(NDVI)and its driving forces based on long time-series data.Piecewise regression was used to examine whether there was a turning point of the trend of NDVI and climatic variables.Pearson correlation analyses were conducted to quantify the relationship between NDVI and climatic factors.Stepwise multivariable regression was used to quantify the contributions of climate variables to the temporal variations in NDVI.Important Findings We found a turning point of NDVI trend in 2008,with GIMMS NDVI indicating a slight increase of 0.00022 yr?1 during 1982–2008 to an increase of 0.002 yr?1 for GIMMS NDVI during 2008–2015 and 0.0018 yr?1 for MODIS NDVI during 2008–2018.Precipitation was the predominant driver,and air temperature and vapor pressure deficit exerted a minor impact on the temporal dynamics of NDVI.Overall,our results suggest a turning point of NDVI trend,and that recent warmer and wetter climate has caused vegetation greening,which provides insights for better predicting the vegetation cover in this region under changing climate.

The Ecosystem Condition of Basin of the Trans Border River Argun in Zabaikalsky Krai, Russia

Cyclic climatic changes, as well as the press of anthropogenic impact, affect ecosystems of the river Argun basin. Specialization of basin management is industrial and agricultural. The main impact is connected with the development of mining companies （including the mining of ore and placer gold）, energy facilities, and the formation of reservoirs in the basin of rivers： the Argun -- the Hailar. As a result of natural and anthropogenic pressure, the limiting factor for ecosystem exploitation in this basin is water resources （water deficiency and its quality）.