The Association Between Litterfall And Variation Of Climate Factors And Population In An Evergreen Broad-leaved Forest In Tiantong,Zhejiang Province

Litterfall as one of the important components of the forest ecosystem,detecting the driving factors of litter production is of important for studying the material cycle of forest ecosystem.Meteorological factors and population change are two categories of common factors for affecting the litter production,but the targeted studies which based on long-term data are still lacking.For this purpose,we analysed 1)the association between total litterfall and meteorological factors based on the data which is collected during 2012 to 2016,2)the influence of population variation which near the litter traps between 2010 and 2015 on leaf litterfall.The main results of this study are as follows:(1)Totally 331.94 kg litterfall are collected in 187 litterfall traps during 5 years.The average is 686.84 g m-2 a-1.The proportion of leaf,debris,branch,reproductive organ and bark are 72%,16%,6.4%,3.8%and 2%of the total litterfall respectively.The rhythm of total litterfall and leaf litterfall are similar.The branch,reproductive organ,and bark litterfall do not find obviously rhythm.These results indicate that leaf litterfall is the most important component of total litterfall.(2)The responses of total litterfall and other part of litterfall to meteorological factors are different.The total and leaf litterfall are mainly under the positive influence of half month average temperature.The branch litterfall is mainly under the positive influence of half month minimum temperature,half month average precipitation and 10 min average wind speed.The bark litterfall is mainly under the positive influence of 1 h maximum wind speed,half month average precipitation and half month minimum temperature.The reproductive organ litterfall is mainly under the positive influence of half month average temperature and 1 h maximum wind speed.These results represent that temperature is the important factor for total litterfall and other part of litterfall.Because the total litterfall and leaf litterfall are only influence by temperature,and the changes of temperature are of obvious rhythmicity,the litter rhythm of total litterfall and leaf litterfall are obvious.However,bark and reproductive organ litterfall were influence by temperature,wind and precipitation,and these two meteorological factors are random.So the rhythm of branch,bark and reproductive organ litterfall are not obvious.In addition,due to the different litter rhythm of evergreen and deciduous trees,the leaf litterfall of these two life form trees was influence by different meteorological factors.The leaf litterfall of evergreen trees was mainly positive influenced by half month average temperature,and the leaf litter fall of deciduous trees was mainly positive influenced by half month average precipitation.(3)Compared with 2010,the number and biomass of evergreen tree around the litter frame increased significantly in 2005.Among them,the litter yield was affected by the population growth which the evergreen tree species were increased significantly.However,the population species and biomass of deciduous trees had no significant effect on its’ leaf litter yield.In addition,the variation of population numbers and biomass of the spices which less increased or reduced in its’s population number and biomass had no significant effect on leaf yield.So the population growth could increase its leaf yield in the evergreen tree species.In summary,the whole litterfall and leaf litterfall are mainly affected by external temperature with a season rhythm in the evergreen broad-leaved forest in Tiantong.While the evergreen tree species with faster growth of biomass could increase the leaf litterfall in the years.Thus,the litterfall may be affected by both external meteorological factors and internal population changes.