The Change Character Of Climate And It's Influence On Forest Related Climate Variables

Climate change and it's influence on ecological systems is one of main concerns recently. These study use 34 weather station's daily temperature, precipitation and evaporation data, analysis the spatial and temporal change character of main climate variables in Northeast China, and its influence on forest related climate indicators. Main conclusion is:(1) Annual average daily maximum air temperature increased at the rate of 2.33℃(100a-1); annual average daily minimum temperature increased at the rate of 4.48℃(100a-1); diurnal temperature range decreased at the rate of 2.15℃(100a-1); annual average daily mean air temperature increased at the rate of 3.61℃(100a-1)(2) The temporal change character of diurnal temperature range can be divided into two distinct regimes. During the first regimes, diurnal temperature range decreased rapidly during 1960 to 1990, mainly caused by the temperature increase at faster rate in the night time than in the day time. During the second regimes, diurnal temperature range reversed to increasing trend, mainly caused by temperature increased at faster rate at these time. The changes of diurnal temperature is mainly correspond with solar irradiance. As these two variables highly related each other, it seems that the changes of solar irradiance influence the changes of diurnal temperature range through it's effect on daytime temperature.(3) The annual total precipitation amount with slightly decreasing trend, with the rate of 7.07mm per decade; the annual total precipitation frequency decreased rapidly, with the rate of 3.15n per decade. The main change character of precipitation in northeast China is rapid decrease of precipitation frequency, and the rate of change of precipitation frequency is higher than precipitation amount. The average precipitation intensity for rain days with a increase trend. The changes of precipitation amount is mainly caused by the changes of heavy precipitation events, especially for the highest decile. The changes of precipitation frequency is mainly caused by the changes of the lowest decile. The changes character of precipitation intensity is decrease of heavy precipitation frequency and increase of heavy precipitation intensity.(4) Pan evaporation amount with decrease trend, with the rate of 10.96mm per decade. The rapid decrease of pan evaporation amount is from the end of 70s to the end of 80s, during 90s the pan evaporation amount with increase trend. Our research support the interpretation that the change of pan evaporation is mainly caused by the changes of solar irradiance. The water condition influence the sensitivity of pan evaporation amount to the changes of solar irradiance.(5) Annual number of frost days with decreased trend, with the rate of 2.5d per decade. Analysis based on the annual and seasonal number of frost days relationship with other climate variables, water vapor pressure show high and consistent relationship with the number of frost days. The temporal changes of frost day and frost free season seen the transition year to rapid change are later than temperature. Our analysis support the result that decrease in the number of frost days and lengthen of frost free season.(6) The growing degree days showed rapid increase trend for each base temperature. Lower base temperature with higher magnitude of change and the change rate difference between differ base temperature is obvious. Longer growing season length always means higher growing degree days.(7) The increase of dry days caused increased in length of prolonged dry episodes, and the decrease of dry days caused decreased in length of prolonged dry episodes...