The Study On Validation Of Understory Shrubs's Biomass Equations And Biomass Distribution Patterns For Understory Shrubs

Forests shrub is one part of the forest structure as well as important potential carbon. It gradually became a main method of estimating shrubs biomass by constructing the shrub biomass equation. Validating is a significant step of constructing the shrub biomass equation while a foundation for the application of equation. Constructing the shrub biomass equations in natural secondary forest in northeast of China by choosing a number of standard wood, the best single species and mixed species biomass equation were selected using the absolute main relative error and average relative error indexes as shrubs biomass equation screen and validation of biomass equation, meanwhile they were validated among species-specific scale and quadrat scale which provided the basis for the application of shrub biomass equation at single species-scale applied at multiple scales.The result of screening and validation of biomass equation indicated as follows:1,The best biomass equation form was mainly power function while partial equations were linear regression equation such as Spiraea ussuriensis, Deutzia amurensis, Viburnum burejaetioum. Selecting of equation variables was related to shrub type, variable of tree-type shrub was mainly D10 or D102H; However, variables of representative shrub were CAH or CA.2,At species-specific scale,the estimating effects of all the pecies-specific biomass equation were better than mixed species as for tree-type shrub, according to representative shrub,more than 40% of the mixed species biomass equation were better than single species. The estimated error of all the best biomass equation of the shrub organ at single species-scale were in the reasonable scope.3,The estimated error of single species and mixed species biomass equations were significantly increased. The number of the quadrat whose estimated error of biomass equation for single species exceeded reasonal range was little which cannot effect the application of the equation. On the contrary, the number of the sample whose estimated error of biomass equation for mixed species exceeded reasonal range was much. Thus, It was not suitable for estimating shrub biomass at quadrat scale.Spatial distribution pattern is one of the most remarable feature of plant flora. Digital elevation model was applied in the study of spatial distribution pattern in shrub biomass. The result showed that terrain was a important factor for the spatial distribution pattern in shrub biomass. The differentiation of terrain resulted in the difference at the distribution of shrub species as well as individual size which caused distinction of spatial distribution pattern in shrub biomass. At different slope position, shrub biomass at downhill were significantly higher than middle and uphill while uphill was a little more higher than at middle, they have little differences. At different slope degrees ,shrub biomass was gradually declined associated with increase of slope degree;There existed obvious differences among spatial distribution pattern at slope degree of all kinds of shrub biomass; At various slope directions, shrub biomass that had no slope direction was dramatically higher than the other slope direction, the biomass at half-sunny slope was the smallest, It was little difference among sunny slope direction, half-sunny slope and half shaded slope.This study partition the forest type following slope position in order to eliminate effect of slope position on the spatial distribution pattern in shrub biomass at different forest type to come to a transverse comparision. At uphill, shrub biomass of different types according to the order were forest of Mongolia>populas>Betula platyphylla>Miscellaneous wood; At middle slope position, shrub biomass of different types according to the order were hard broadly> Mongolica> populas; At downhill, the order were hard broadly> Miscellaneous wood> Betula platyphylla. There were large differences of shrub biomass among different forest types (weighed average biomass in area) the shrub biomass of hard broadly was the biggest, populas was the smallest, meanwhile Mongolia and Miscellaneous wood had no difference.Estimating method of average biomass is a common method for estimating biomass in area, This paper put forward a estimated method of weighing average biomass in area which was based on slope-forest type that was according to undergrowth biomass shrubs at different factors of terrain and the spatial distribution patterns in forest types. When to compare the estimated method of average biomass with weighed average biomass which was based on slope position -forest type, Betula platyphylla, populas and Mongolia had little difference, Hard broadly was underestimated for 10.25%, Miscellaneous wood was overestimated 22.66%.The estimating method of weighed average biomass based on slope position -forest type made full consideration that the influence of terrain and forest type to the spatial distribution pattern of shrub biomass. It reflected shrub biomass in the same forest type more authentic and objective, at the same time ,It could provide a more efficient approach for estimating undergrowth biomass shrubs and Carbon amount more exactly.