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Wang F.,Shandong Forestry Research Academy | Yamamoto H.,Yamaguchi University | Li X.,Shandong University | Zhang J.,Northeast Normal University
Ecological Informatics | Year: 2014

The ornamental value of many trees is often based on their special colour, shape and structures. Its autumn leaf colour makes sweet gum (Liquidambar styraciflua L.) a favourable ornamental tree species for landscape beautification and urban greening. In addition to specific genetic control, to some extent, environment plays an important role in sweet gum colour changes. In this study, leaf-reddening events in the individual leaves and crowns of sweet gum trees were studied by analysing the ecology of sweet gum trees planted on a gradient of soil types, by comparing pruned and unpruned trees, by severing certain leaf veins and by measuring the snapping strength of the petiole. High-temperature areas on the severed leaves were detected using thermography. Low stomatal conductance and high leaf temperature rapidly appeared at the stressed area in severed lobes because of water stress and a related transpiration-cooling failure, especially in direct sunshine or on dry, hot summer days. The consistent relationship between the reddened and high-temperature areas indicates that a persistent transpiration-cooling failure resulted in local-area reddening on sweet gum leaves and the formation of a protective layer with high anthocyanin content. A significant relation between the snapping strength of the petiole and leaf reddening suggests that a persistent water imbalance during the formation of the abscission zone accelerates the sweet gum leaf reddening. Namely, a persistent transpiration-cooling failure during the defoliation process induces protective responses of the leaf. The rapid water loss of sweet gum juvenile leaves indicates that the reddening of the leaves may be a sensitive response to the changing properties of the leaf cuticle. © 2013 Elsevier B.V. Source

Wang F.,Shandong Forestry Research Academy | Zhang J.,Northeast Normal University
Natural Hazards | Year: 2015

During the process of climate change in East Asia since the 1980s, increasing climate influence and meteorological hazardous events occurred, such as persistent drought, strong typhoon, and intercurrent meteorological extremes. The maximum temperature and persistence of rain-free days rose during the most recent 30 years in many cities in China. The combination of these extremes may evidently decrease the threshold of tree responses to the extreme stresses, even cause pine wilt in the area. By studying the geographic distribution of pine wilt disease, climate change characteristics, and the relationship between resin excretion and meteorological hazardous events, the relationship between pine wilt events and the summer droughts and strong typhoons in East Asia was investigated. The spatial and temporal consistency of the prevalence of pine wilt disease with climate change characteristics in both China and Japan suggests that pine wilt is related to local environmental variance. After extreme summer drought and strong typhoons, the ability of pines to excrete oleoresin was often reduced, and deaths were observed. The special adaptive characteristics of pines to meteorological hazard events during climate change, such as stopping or reducing resin excretion, may be the key of their wilt. © 2015, Springer Science+Business Media Dordrecht. Source

Wang F.,Shandong Forestry Research Academy
Journal of Forestry Research | Year: 2010

The effects of major veins severing on morphological and physiological features of sweetgum (Liquidambar styraciflua L.) leaves were investigated by observing leaf color change and measuring leaf temperature, green/luminance (G/L) value of half-lobes, leaf stomata conductance, and water content in Yamaguchi University, Japan. The palmately veined leaves of sweetgum (Liquidambar styraciflua L.) were found more sensitive to the major vein severing than that of other species. Major veins severing resulted in serious water stresses, as indicated by the persistent reddening and/or advanced reddening of local leaf, lower leaf stomatal conductance, and higher leaf temperature, etc. Severed leaf can be clearly divided into non-severed area, transitional area, and stressed area, which the three areas have different colours and temperature. The major vein barrier can also be seen clearly. The persistent reddening and advanced reddening seem consistent with the phenomenon of red crown top of some sweetgum trees and may have similar mechanism. © 2010 Northeast Forestry University and Springer-Verlag Berlin Heidelberg. Source

Wang F.,Shandong Forestry Research Academy
Chinese Journal of Applied Ecology | Year: 2012

The occurrence and prevalence of pine wilt disease cause huge losses to Japan, China, and South Korea in East Asia, and have received concerns from many countries. By the methods of field observation and meteorological data analysis, this paper studied the characteristics of the occurrence and prevalence of pine wilt disease and their relations to the meteorological disaster events. In Japan, China and South Korea, the meteorological extreme events of persistent summer drought and strong typhoon could trigger the occurrence of pine wilt. In extremely dry and hot environment, pine trees often appeared energy metabolism imbalance and entire tree wilt. However, in the years with lower temperature and more rainfall, less or nearly no pine wilt event occurred. It was suggested that before the attack by pine wood nematode and its vectors, the vigor of the pines had already declined, and thus, pine wilt disease could be confined in the areas often hit by summer drought and strong typhoon events. In the areas with suitable natural environment characterized by less summer drought and strong typhoon events and no improperly enlarged pine planting, there would be little possibility of widespread occurrence of pine wilt disease. Source

Wang F.,Shandong Forestry Research Academy
Natural Hazards | Year: 2014

Environment plays an important role in the interaction between host and pathogen and in the expression of diseases. Climatic differences among East Asia, Eastern USA, the Mediterranean and Northern Europe were compared against differences in the prevalence of pine wilt disease. This disease was prevalent in East Asia where there are frequent summer droughts and typhoons. Northern Europe (EEM) has a mild climate with very few summer droughts and tropical cyclone impacts and no pine wilt disease. The Mediterranean occasionally suffers climatic extremes, and pine wilt disease occurs infrequently and in localized area. The Eastern USA has climatic variability intermediate between Northern Europe and East Asia. Hurricanes are fewer and weaker compared to typhoons in Japan, China and Korea. Pine wilt disease occurs only in exotic pines in the USA. The climate of Hokkaido in Japan, where there is no pine wilt disease, is similar to that of the Eastern USA. With special stress adaptability, pines (Pinus spp.) usually respond to the meteorological extremes entirely and excrete large amount of resin. Disturbing by the hazardous summer drought and strong rainless typhoons (foehn-like typhoon), water and energy imbalance of pines often occurred so as to halt the resin excretion and trigger them into wilt. © 2014 Springer Science+Business Media Dordrecht. Source

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