关键词: 琯溪蜜柚, 琯溪蜜柚, 山地果园, 立地条件, 径流, 氮, 磷

Abstract: Based on the daily precipitation data of 80 meteorological stations in Heilongjiang, the variation characteristics of summer rainfall and rainstorm in recent 55 years (1961 to 2015) were analyzed to provide a basis for grain production. The study was carried out by using trend coefficients and GIS spatial interpolation techniques from the aspects of summer rainfall, the trend of rainfall variation, rainstorm frequency and the trend of rainstorm variation. The results showed that the Lesser Khingan Mountains and the Zhangguangcai Mountains had the highest summer rainfall of above 360 mm, the lowest was in the Sanjiang Plain and the Songnen Plain, which was between 300 to 320 mm. The summer rainfall increased in the Songnen Plain and the Great Khingan Mountains, and decreased in the Lesser Khingan Mountains and Sanjiang Plains. The average summer rainfall of Heilongjiang showed a decreasing trend, with an average decrease of 2 mm every 10 years, the lowest was in the 1970s and the highest was in the 1980s. The most average number of rainstorm days occurred in the southwest of the Lesser Khingan Mountains and the west of Zhangguangcai Mountains, followed by the Sanjiang Plain and the Songnen Plain, the Great Khingan Mountains had the least rainstorm days. Rainstorm occurrence stations showed a significant upward trend, increased by 2.3 stations every 10 years, the number of rainstorm occurrence stations was the least in 1970s and the most after 2010. The maximum daily rainfall basically decreased from southwest to northeast. The maximum daily rainfall in most areas of southwest was above 120 mm, and that in northeast was below 120 mm.