Study On Prediction Of Surface Dead Fuel Moisture Content In Maoershan Forestry Farm

Dead fuel moisture content(DFMC) prediction is a very important component in fire weather and fire behavior forecast.Methods based on timelag and equilibrium moisture content are the most important ones in DFMC prediction,among of those,Catchpole et al.method, which was based on Nelson model,has been used widely and opened up a broad prospect.But there are still several questions need to be solved:①Model performance was high in Catchpole et al.(2001) paper because validation was made by modelling data,whether it would be the same or not when using other data has never be known.②The impact of data length on modelling has also never be known③There are four models at present.Method in Catchpole et al.(2001) paper was based on Nelson(1984) model which had been shown(Liu Xi et al.2007) had a worse performance than Simard(1968) model which is used in NFDRS.So the performance has never be known when any other model is used in Catchpole et al.(2001) method.According to continous observations,the questions above are discussed in this paper. The application of Catchpole et al.(2001) method of different kinds of fuels' Timelag and EMC estimates of Betula platyphylla,Meadow,Hard-width,Shrubs,Mongolian oak and Fraxinus mandshurica were made,and moisture content was predicted on the basis.The results indicate that:1) Catchpole et al.method(When modelling data length is 84)performs well in fuel moisture prediction,It shows Catchpole et al.(2001) method has a strong applicability in estimating fuel moisture form field data.At least eghity data or more is advised to be used in application and thirty data can also be used when error standard is not high(3%,for example.).2) The predicting results based on Nelson(1984) model perform better than that based on Simard model when data length is short,but when it is over 84,the two performances are not significant different.3) forest types of delay and little effect on equilibrium moisture content;stratified significant impact on the delay at a temperature of 20℃,relative humidity 25%～45%of the scope of the impact on the equilibrium moisture content significantly.4) The moisture content of different forest types was not obvious difference between the forecast error;different layered moisture prediction:litter＜duff＜mixed fuel＜humus,upper and middle error generally are outside the scope of 3%lower and 1%in the mixed layer are outside the scope of.5) The moisture content of litter forecast,based on the Nelson model is better than the overall effect of model Simard.