Seasonal Dynamics And Characteristics Of The Leaf Area Index In The Mixed Broad-Leafed Korean Pine Forest In Xiaoxing'an Mountains, China

Forest leaf area index is one of the most important vegetation parameters, it takes an important role in meteorology, agriculture and ecological environment research. The accurate measurement of LAI is the hot topic of research.The mixed broad-leafed Korean pine forest is the climax vegetation types in the Eastern Mountainous Region of Northeast China. In this paper, hemispherical photography, leaf fall collection and leaf opening survey were used to determine the seasonal dynamics and the character of the LAI in mixed broad-leafed Korean pine forest, and revealed the relationship between hemispherical photography and true-LAI. The litter fall was collected in litter traps system is considered to be reference, The LAI Of the forest and each broad-leaved species provided a basis for further study and reference data.Some conclusions have been drawn as the following:1) In the leaf fall period of 2007, Pinus koraiensis accounted for the largest share (37.7%) of the total LAI value of reduction, and all the broad-leaved tree species accountfor 52.8%. Survey in 2008, the proportion of Pinus koraiensis dropped to 30.3%, The LAI-valueof other species also had changes in LAI-value. The total proportion of broad-leaved species rose to 61.3 percent out. Compared to the DBH, height, crown area of unit area in the stand, LAI of broad-leaved species have the strongest correlation with BA. In 2007 compared with 2008, litter period about 15-20 days in advance.2) Leaf area index was in a single peak growing season curve. In the 2007 survey, the highest value appeared in July to 4.23, the LAI-value between July and September tended to be stabilized in September begin to decline, November 15 reached the minimum value 2.99, Survey in 2008, the maximum measured LAI-value was 4.07, minimum was 2.72 and also found in the November.3) The LAI which was analyzed from hemispherical photograph using Hemiview2.1 had a better fit with the true value, when the zenith was 87.5°. The regression curves with R~2=0.906. The hemispherical photography introduced a underestimated LAI-values, about 23% on average..4) The leaf opening survey in 2008, the LAI growth curves of each broad-leaved species coincided with the logistic curve. Different species had a different leaf unfolding prime, all achieved the maximum in July.