Liu Hongyan

Tree-ring based PDSI reconstruction since AD 1842 in the ortindag sand land, east inner mongolia

Based on three Chinese pine (Pinus tabulaeformis Carr.) and one Meyer spruce (Picea meyeri Rehd. et Wils.) ring-width chronologies, a 163-year drought history was reconstructed in the eastern Ortindag Sand Land. All tree-ring chronologies show large inter-annual variations and strong common signals and fairly consistent variation between different chronologies, indicating that they are excellent proxy of regional climate. A regional chronology (RC) was established by averaging the four standard chronologies and further employed for the analysis and climatic reconstruction. The analysis revealed that tree growth is primarily limited by low precipitation in February–March and June–July and high temperature in May–July. In addition, RC has high correlations with the monthly Palmer drought severity index (PDSI) prior to and during the growing season because the PDSI considers the accumulation of the droughts. Response function analysis revealed that RC only exhibits significant correlations with the PDSI in June and July (close to the 95% significance level in May). Because May–July is a critical period for tree growth, the average May–July PDSI (PDSI5–7) was reconstructed back to 1842 using RC in the Ortindag Sand Land. The reconstruction can explain 52% of the PDSI variance and the equation was rather stable over time. It agrees well with the variation of the average dryness/wetness indices in North China, and captures the decline process of the East Asian summer monsoon since the mid-1960s. It is worth noting that the Ortindag Sand Land has experienced the most severe drought in the recent 40 years based on the 163-year drought reconstruction. Like summer precipitation in North China the reconstructed PDSI5–7 also displays a 20-year oscillation.

Water-saving and drought-resistance rice and its development strategy

Water-saving and drought-resistance rice (WDR) is a new type of rice with not only high yields and good quality, but also water-saving and drought-resistance characteristics. When this crop is irrigated, its grain yields and quality are equivalent to those of paddy rice, but its water requirement is only half that of paddy rice. It retains good yields in uplands because of its drought resistance. Furthermore, the sowing and cultivation of this rice requires lower inputs and less energy, and thus, it is very environmentally friendly. Here, we summarize the physiological and genetic mechanisms of water saving and drought resistance in WDR varieties, and the achievements in WDR breeding and genetics in the past decade. We discuss: 1) drought avoidance and drought tolerance, both of which improve yields under drought stress; 2) methods to evaluate drought resistance that have been used in breeding programs; 3) analysis and discovery of drought-resistance gene resources; and 4) analysis of the molecular mechanism of WDR in WDR varieties.

Artemisia pollen-indicated steppe distribution in southern China during the Last Glacial Maximum

Abstract The Last Glacial Maximum (LGM) was the coldest period during the previous 20,000xa0years. There have been different points of views on steppe distribution during the LGM period in southern China, partly due to the different interpretations of Artemisia occurrences. To make a reliable interpretation of the pollen fossil Artemisia , the modern distribution of Artemisia species and the relationship of pollen with climate and vegetation over a large spatial scale in China was thoroughly analyzed. Information about Artemisia species and pollen distributions used in this paper were collected from published works completed by other researchers as well as ourselves. The southern limit of steppe vegetation during the LGM period was interpreted from the published contour map of Artemisia pollen percentages during the LGM. Artemisia species in China are mostly distributed either in the horizontally distributed steppe regions or in the vertically distributed desert-steppe in the desert region, which indicates a cold and dry climate. The steppe is a distribution center of Artemisia pollen. Fractions of Artemisia in surface pollen assemblages are lower in both the desert and the temperate forest. Neither high Artemisia species cover nor high percentages of Artemisia pollen were found in the coast areas of China. Twenty-five percent of Artemisia pollen in sediments might indicate a local occurrence of steppe vegetation. Percentages of Artemisia pollen in the subtropical and tropical forest are less than 10%. A close relationship between Artemisia pollen and temperate steppe in China is demonstrated. The southern edge of the steppe vegetation during the LGM might be along the middle reach of the Yangtze River. Our results support the hypothesis that the isolated high fraction of Artemisia pollen along the northern edge of the South China Sea was transported from a large source area.

Impact of Climate Change on Urban Agglomerations in China’s Coastal Region

Abstract Climate change and urbanization issues are the two key factors that make humans liable to be affected by disasters, which are overlapped in urban agglomeration. The five big urban agglomerations of China with strong economic power are the important engines for national economic and social development. However, being in the sea-land mutual interaction belts with a vast hazard-bearing body, they are affected by sea-land compound disasters, and are liable to suffer heavy disaster losses with climate change. It is suggested that government departments concerned should fully recognize the impact of climate change on coastal urban agglomerations, propose strategies as soon as possible, and integrate the impact of climate change and adaptation countermeasures into the various kinds of social-economic development plans for coastal urban regions.

The Deserts of China

This chapter provides features of environmental factors and phytogeographical divisions for desert vegetation in China. There are three kinds of desert vegetation in China: semi-desert, true desert, and extremely arid desert. The desert vegetation is distributed on different land forms with diversified soil feature, extending in NW China with mean annual precipitation less than 200 mm. Dominant species in the desert vegetation in China include eight life forms.

Vegetation and Environment

This chapter provides an overview of desert flora and plant communities. The vegetation-environment relationships were explained with two case studies, true desert in the Jungar Basin and extremely arid desert in the Anxi Extremely Arid Desert National Nature Reserve. There are 610 species in the desert of China, which can be classified into Central Asian element and Inner Asian element. The plant communities are abundant caused by diversified topography and soil features.

The Inland Eastern Desert of Egypt

The inland part of the Eastern Desert of Egypt forms an ecosystem with characteristic habitats: (1) rocky surface, (2) erosion pavement, (3) gravel desert, (4) slopes, (5) cliffs, and (6) desert wadi, which represents a drainage system collecting water from extensive catchment area. The geographic position of the mountainous range along the Red Sea coast is very conspicuous. The flora and vegetation of the Gebel Elba mountainous group is much richer than that of the other coastal mountain, where the Palaearctic and Afrotropical regions meet. The species composition of the Gebel Elba National Park was greatly influenced by disturbances such as severe cutting of trees and shrubs either for domestic fuel or charcoal production and browsing. In terms of classification and ordination, the vegetation and environment in northern wadis and southern wadis in four transects representing three different types of desert running from the Nile Valley to the Red Sea coast were investigated. Based on the current status of flora of the Eastern Desert, a biogeographical analysis and phytogeographical divisions of the were re-assessed.

The Coastal Desert of Egypt

The coastal deserts in Egypt are found along the Mediterranean (east and west), the Red Sea, and the Gulfs of Suez and Aqaba in Sinai Peninsula. The variations in their floristic composition and vegetation structure are varied considerably. The association between the landform units and their floristic features showed significant differences. In the meanwhile, the biological spectrum and chorological analyses of the flora exhibited a general trend in both dominance and structure. Climatic variations, especially rainfall, between the different geographical areas play a profound role in the species distribution patterns. The relationships between the vegetation and the prevailing environmental characteristics indicated the importance of certain soil factors such as coarse and fine sediments, moisture content, electrical conductivity, pH, and organic matter. The distance from the sea and altitude were other significant factors in delimiting species distribution.

The Sinai Desert

The Sinai Peninsula is currently recognized as one of the central regions for biodiversity in the Middle East by the World Conservation Union. It is rich both in the number of species and the high percentage of endemics. The roughness in geomorphology leads to differentiation of enormous number of microhabitats and landforms which resulted in relatively high diversity in ecosystems and flora. The most conspicuous inhabited oasis in south Sinai is Feiran Oasis which is considered as the largest receiving amounts of runoff water from the drainage system of Wadi Feiran. The small size of Feiran Oasis, the limited water resources, the rapid development due to increased touristic and population pressures, as well as the present serious socio-economic situation may cause the destruction of the remaining natural habitats in the near future. Recently, it is subjected to severe destruction and dryness of a great deal of its characteristic date palm orchards habitat. Out of the 33 species which recorded for the first time from Feiran Oasis, 13 were invading xerophytes, growing in fields and orchards, and behaving as field weeds. Floristic analysis, species distribution, and soil–vegetation correlations in Wadi Solaf, W. El-Akhdar, and W. Romana (as inland wadis) were compared to W. Kid (a coastal wadi). In the eastern sector of Central Sinai, plant communities and vegetation analysis were performed along four tracks (unpaved and unaccessible roads): Nekhel–Al-Qasimia, Al-Qasimia–Al-Kuntella, Al-Kuntella–Al-Thamad, and Nekhel–Al-Malha.

The Deserts of Pakistan

Pakistan is a subtropical country spread over an area of 79.6 million hectares (mha) lying between 24° and 37° N and 61° and 75° E. Most of the area is semiarid to arid, extending over 70 mha (87.94% of its land mass), receiving 250 mm annual rainfall. The deserts of Pakistan cover 11 mha (13.82%) of the land situated in the central and southeastern regions. These areas are broadly separated and are located between 100 and 1000 m above sea level. These deserts are monsoon in type, referring to a wind system marked with seasonal fluctuation in response to temperature variations between continents and oceans. The southeast-directed winds of the Arabian Sea supply heavy summer rains. The aridity is characteristic of a desert, with erratic rainfall occurring in clusters. The most dominant and frequent tree species in the desert habitat include Acacia senegal, Acacia nilotica, Azadirachta indica, Capparis decidua, Prosopis cineraria, Salvadora oleoides, Tamarix aphylla, and Tecomella undulata, with Prosopis cineraria being the most dominant and frequent. Among shrubs, Acacia jacquemontii, Aerva javanica, Calotropis procera, Calligonum polygonoides, Dipterygium glaucum, Euphorbia caducifolia, Fagonia indica, Haloxylon salicornicum, Leptadenia pyrotechnica, and Crotalaria burhia are dominant. Ephemerals are an important component of the desert habitat, here represented mostly by Boerhavia procumbens, Convolvulus prostratus, Gisekia pharnaceoides, Heliotropium strigosum, Indigofera argentea, Indigofera cordifolia, Indigofera linifolia, Limeum indicum, Mollugo cerviana, Senna ialica, and Tephrosia purpurea. Grasses are very prominent inhabitants in deserts, including Aristida spp., Cenchrus biflorus, Cenchrus ciliaris, Eragrostis spp., Panicum turgidum, Pennisetum divisum, Saccharum spontaneum, and Stipagrostis plumosa. Abutilon bidentatum, Abutilon pakistanicum, Alysicarpus monilifer, Alysicarpus tetragonolobus, Caralluma edulis, Cenchrus prieurii, Commiphora wightii, Convolvulus scindicus, Gisekia pharnacioides, Ephedra ciliata, Gynandropsis gynandra, Monsonia heliotropioides, Rhynchosia schimperi, and Tecomella undulata are some of the threatened species that are used by the inhabitants to meet their various socioeconomic needs. Pragmatic conservation measures are required to protect such habitats, because they represent threatened or rare and endemic species that are of economic importance to the local communities and thus are used unsustainably.