Dual Damage To Trees From Climate Warming And Extreme Low Temperature In Late Spring In Shanxi

Increasing average temperature, especially winter and spring temperature and more events of extreme low temperature under global warming will lead to more serious dual damage to plant growth and development, however, there has been no many study reports on this issue. This project was designed to study the dual damage to trees from climate warming and extreme low temperature in late spring on the basis of analyzing the climate warming characteristics of Shanxi and through analyzing both the damage to trees caused by the extreme low temperatures in late spring in Gaoluo Forest Farm located in Zhongtiaoshan in April 2013 and the damage to trees from the extreme late frost in the tree nursery of Shanxi Agricultural University in May 2014. The results show that:(1) In the past 50 years or so, the average air temperature, especially the winter and spring temperature has been increasing greatly in Shanxi, as same as the global and national trend. Over 30 years since 1990, the average temperature in winter and spring in Taigu increased by more than 1℃. The significant increase of temperature in winter and spring inevitably leads to tree phenophase earlier and accordingly causes more severe damage to trees from extreme low temperatures in late spring. The severe damage to forest trees, rare in decades, from extreme low temperature in late spring occurred in Gaoluo Forest Farm in 18-20 April 2013 and the rare seedlings frost damage occurred in the tree nursery of Shanxi Agricultural University in May 4,2014, were just dual damages from both climate warming and extreme low temperature in late spring.(2) During the winter and early spring of 2012-2013 the temperature was higher than usual in Gaoluo Forest Farm, which leaded to plant spring phenophases earlier. Even more, growth and development like sprouting, leafing, flowering and fruiting were greatly promoted due to the extreme high temperature from April 10 to 17,2013. The advanced plant phenophase caused more severe frost damage to trees following the continuous extreme low temperatures from April 18 to 20. This frost damage was rare in decades in this area. The investigated plants were total 54 species belonging to 30 families and 49 genera, including 27 tree species,11 shrubs,3 vines and 13 herbs. Of the 54 species 28 suffered from frost damage, where the trees, up to 21 species, were the most damaged. The main vegetation species were damaged most seriously, such as Juglans cathayensis, Quercus aliena, Quercu dentata, Diospyros lotus, Cotinus coggygria var. pubescens, Toxicodendron vercifluum, Evodia daniellii. Five shrub and two vine species were damaged, but the herbs were not damaged by frost. The damage degree of the main vegetation species increased with altitude increase of their distribution. The damaged degree of Juglans cathayensis, and Diospyros lotus was more serious than Quercus aliena and Quercus variabilis.(3) The main feature of the frost in May 4-5 in Taigu was it occurred extreme late when the phenophases of all species in the nursery Shanxi Agricultural University have entered the late spring phase, with trees sprouted, leafed or flowered and fruited, as a result, suffered a higher degree of frost damage. There were examined 55 tree species belonging to 25 families and 39 genera survey, where 31 species did not suffer damage and the other 24 species suffered from varying degrees of frost damage. There were 10 species suffered level-1 frost damage, including Zelkova sinica, Zelkova schneideriana, Ulmus davidiana var. japonica, Ulmus laevis, Ulmus macrocarpa, Gleditsia japonica, Fraxinus pennsylvanica, Acer truncatum and Hippophae rhamnoides ssp. sinensis. Six species suffered level-2 frost damage, including Amygdalus triloba, Picea meyeri, Pinus tabulaeformis, Sophora japonica f. pendula, Xanthoceras sorbifolia and Sophora japonia. Other 8 species had level-3 frost damage, includng Quercus variabilis, Quercus acutissima, Quercus acutissima, Quercus aliena, Queercus dentata, Picea wilsonii, Juglans regia, Catalpa ovate and Hibiscus syriacus. The tree seedlings suffered damage more than the shrubs, with the damage ratios of 46.5% and 33.3% respectively. More species that naturally distribute in mountainous area suffered frost damage than the species that naturally distribute in hilly and plain areas and the species that naturally distribute in both the above two areas, with the damage ratios of 85.7%,40.0% and 33.3% respectively. The ratio of both alien and native species suffered from frost damage were similar, being 44.4% and 42.1% respectively.The scientific significance of this study is to understand the dual influence on plants, especially trees by global warming and extreme low temperatures in late spring. This study also have important practical production significance. Through the study, frost resistance of the tree species to extreme low temperatures in late spring can be comprehensively determined, which provides a scientific basis for selecting afforestation and greening tree species, and also provides references for prevention and protection of trees from frost damage in late spring.