The change characteristics and trends of the regional climate in the source region of the Yellow River, and the response of runoff to climate change, are analyzed based on observational data of air temperature, precip...The change characteristics and trends of the regional climate in the source region of the Yellow River, and the response of runoff to climate change, are analyzed based on observational data of air temperature, precipitation, and runoff at 10 main hydrological and weather stations in the region. Our results show that a strong signal of climate shift from warm-dry to warm-humid in the western parts of northwestern China (Xinjiang) and the western Hexi Corridor of Gansu Province occurred in the late 1980s, and a same signal of climate change occurred in the mid-2000s in the source region of the Yellow River located in the eastern part of northwestern China. This climate changeover has led to a rapid increase in rainfall and stream runoff in the latter region. In most of the years since 2004 the average annual precipitation in the source region of the Yellow River has been greater than the long-term average annual value, and after 2007 the runoff measured at all of the hydrologic sections on the main channel of the Yellow River in the source region has also consistently exceeded the long-term average annual because of rainfall increase. It is difficult to determine the prospects of future climate change until additional observations and research are conducted on the rate and temporal and spatial extents of climate change in the region. Nevertheless, we predict that the climate shift from warm-dry to warm-humid in the source region of the Yellow River is very likely to be in the decadal time scale, which means a warming and rainy climate in the source region of the Yellow River will continue in the coming decades.展开更多
Carex brunnescens, a pioneer plant that has an excellent ability to fix sand in the source region of the Yellow River (Maqu), plays an important role in maintaining the ecosystem stability of alpine grassland in Maq...Carex brunnescens, a pioneer plant that has an excellent ability to fix sand in the source region of the Yellow River (Maqu), plays an important role in maintaining the ecosystem stability of alpine grassland in Maqu. In this study, the biological characteristics (phonological characters, the growth process of overground and underground organs, and the morphological characters of underground organs) of C. brunnescens were studied by a field observation experiment. The results showed that C. brunnescens had the characteristics of turning green earlier than other plants, a long growth period, and two flowering and fruiting cycles. The leaf width, length and number of a single plant, and the density, coverage and leaf density of community increased significantly from the leaf extension period to the fruit mature period and then tended to be stable in the withering period, while the plant height and leaf area of a single plant and the leaf area of community rose significantly at first and then decreased. Underground stems (horizontal and vertical stems) and roots of C. brunnescens could survive in sand at a depth of 0-60 cm. The number of middle roots (0.2-0.5 mm in diameter) was the largest in all soil layers (0-20, 20-40 and 40-60 cm), and the total length of fine roots (〈0.2 mm) were the maximum in the sand at a depth of 20-40 cm, while the total length of middle roots was the maximum in the sand layer at a depth of 0-20 cm. The length, fresh weight and dry weight of the main root, horizontal and vertical stems was the maximum in the sand layer at a depth of 10-30 cm and was the minimum in the sand layer at a depth of 40-50 cm. It is concluded that C. brunnescens can well adapt to the alpine sand habitat of Maqu, can be used as the constructive species for ecological restoration in the alpine desertified grassland of Maqu, and has good popularization and application prospects.展开更多
基金supported by the Key Deployment Project of the Chinese Academy of Sciences (Grant No. Y322G73001)the Major Research Projects of the National Natural Science Fund Project (Grant No. 91225302)the National Natural Science Foundation of China (NSFC) (Grant Nos. 41240002 and 91225301)
文摘The change characteristics and trends of the regional climate in the source region of the Yellow River, and the response of runoff to climate change, are analyzed based on observational data of air temperature, precipitation, and runoff at 10 main hydrological and weather stations in the region. Our results show that a strong signal of climate shift from warm-dry to warm-humid in the western parts of northwestern China (Xinjiang) and the western Hexi Corridor of Gansu Province occurred in the late 1980s, and a same signal of climate change occurred in the mid-2000s in the source region of the Yellow River located in the eastern part of northwestern China. This climate changeover has led to a rapid increase in rainfall and stream runoff in the latter region. In most of the years since 2004 the average annual precipitation in the source region of the Yellow River has been greater than the long-term average annual value, and after 2007 the runoff measured at all of the hydrologic sections on the main channel of the Yellow River in the source region has also consistently exceeded the long-term average annual because of rainfall increase. It is difficult to determine the prospects of future climate change until additional observations and research are conducted on the rate and temporal and spatial extents of climate change in the region. Nevertheless, we predict that the climate shift from warm-dry to warm-humid in the source region of the Yellow River is very likely to be in the decadal time scale, which means a warming and rainy climate in the source region of the Yellow River will continue in the coming decades.
文摘Carex brunnescens, a pioneer plant that has an excellent ability to fix sand in the source region of the Yellow River (Maqu), plays an important role in maintaining the ecosystem stability of alpine grassland in Maqu. In this study, the biological characteristics (phonological characters, the growth process of overground and underground organs, and the morphological characters of underground organs) of C. brunnescens were studied by a field observation experiment. The results showed that C. brunnescens had the characteristics of turning green earlier than other plants, a long growth period, and two flowering and fruiting cycles. The leaf width, length and number of a single plant, and the density, coverage and leaf density of community increased significantly from the leaf extension period to the fruit mature period and then tended to be stable in the withering period, while the plant height and leaf area of a single plant and the leaf area of community rose significantly at first and then decreased. Underground stems (horizontal and vertical stems) and roots of C. brunnescens could survive in sand at a depth of 0-60 cm. The number of middle roots (0.2-0.5 mm in diameter) was the largest in all soil layers (0-20, 20-40 and 40-60 cm), and the total length of fine roots (〈0.2 mm) were the maximum in the sand at a depth of 20-40 cm, while the total length of middle roots was the maximum in the sand layer at a depth of 0-20 cm. The length, fresh weight and dry weight of the main root, horizontal and vertical stems was the maximum in the sand layer at a depth of 10-30 cm and was the minimum in the sand layer at a depth of 40-50 cm. It is concluded that C. brunnescens can well adapt to the alpine sand habitat of Maqu, can be used as the constructive species for ecological restoration in the alpine desertified grassland of Maqu, and has good popularization and application prospects.