暖温带森林生态系统林下灌木生物量相对生长模型

灌木层作为暖温带森林生态系统的重要组成部分,其生物量估算的精确性及便捷性,成为森林生态系统能量流动、物质循环研究的重要环节。目前可用于暖温带森林生态系统灌木层生物量估算的相对生长模型较少。以河北雾灵山国家级自然保护区暖温带森林生态系统为研究对象,建立了该区域15种常见灌木的相对生长模型。研究发现:15种灌木全株和单一器官的最优相对生长方程均以D2H为自变量,分别以幂函数W=a(D2H)b或二项式函数W=a+b D2H+c(D2H)2为最优化回归方程。统计分析结果显示:判断系数R2值介于0.7331—0.9992之间,显著性检验各参数P0.01,满足回归模型的适用性要求。对研究区域常见灌木全株生物量(WTU)的普适性研究发现:以D2H为自变量的二项式函数回归模型WTU=0.0362+297.03D2H-127.1(D2H)2,R2=0.9434,P0.01,普遍适用于除去六道木(Zabelia biflora)和照山白(Rhododendron micranthum)之外的13种灌木植物的生物量估算。此模型对以上2种植物不适用的原因有待进一步研究。

Biomass allometric models for understory shrubs of warm temperate forest ecosystem

The shrub layer is a very important component in the warm temperate forest ecosystem. Accurate and convenient estimation of shrub layer biomass is a key point in the studies of forest biomass, circulation of materials and energy flow of the whole forest ecosystem. Allometric model can serve as a good method to achieve this goal. Studies on this subject have been employed around the world, but few studies have been taken in warm temperate forest in China. Aiming at this point, an investigation on forest understory shrub allometric modeling was established during growing season in 2011 in the region of Hebei Wulingshan Natural Reserve, which has the most typical Warm Temperate forest ecosystem, in North China. Basing on research data of this investigation, biomass allometric models for 15 common shrub species are constructed. The 15 shrub species include: Deutzia grandiflora, Syringa reticulata var. mandshurica, Campylotropis macrocarpa, Rhododendron mucronulatum, Weigela florida, Corylus mandshurica, Zabelia biflora, Rhododendron micranthum, Spiraea trilobata, Hydrangea bretschneideri, Rhamnus bungeana, Philadelphus incanus, Berberis amurensis, Rosa davurica and Radix Acanthopanais. The models of W=a(D²H)^b, W=a+bln(D²H) and W=a+bD²H+c(D²H)² were employed for the selecting of the optimal allometric equation to the 15 shrub species. The research result shows that D²H (where D means basal diameter and H stands for plant height) is the optimal variable of all the biomass allometric models of single organ or total plant. Power function of W=a(D²H)^b or quadratic function of W=a+bD²H+c (D²H)² is selected as optimal allometric equation to the 15 shrub species separately. Statistic results show that R² values are between 0.7331 and 0.9992 and P values are less than 0.01, which mean that the selected optimal equations are applicable to the biomass estimation of the shrub species in our study region. For more convenient application for the shrub biomass estimation in the warm temperate forest in North China, we classified and compared the allometric models of the total 15 shrub species to get a universal model for most of the normal shrubs in this region. The study of total plant biomass universal regression model shows that the quadratic function of W_TU=0.0362+297.03D²H-127.1(D²H)², (R²=0.9434 and P < 0.01) is applicable to 13 shrub species except for Zabelia biflora and Rhododendron micranthum among the 15 species. Further research is still required to explain why this model is not applicable to the rest 2 species.