不同株高的柠条生物量分配格局及其估测模型构建

采用整株挖掘法测量小株（0< h≤ 50cm）、中株（50< h≤ 100cm）、大株（h>100cm）3个株高的柠条（Caragana korshinskii）地上与地下器官生物量，分析其地上与地下生物量分配格局，并利用易测指标对其地上、地下和全株生物量构建估测模型，旨在揭示不同株高柠条的生物量空间结构特征。结果表明：柠条地上各器官生物量所占比例为老龄枝 >叶 >新生枝，随着株丛高度的增加，老龄枝生物量所占比例呈升高趋势，而叶和新生枝生物量呈现降低趋势；柠条地下生物量随着土壤层次增加而呈降低趋势，3个株高柠条的地下生物量主要集中在0~30cm，其中0~5cm所占比例最高，且同一层不同株高的柠条地下生物量所占比例不同；柠条地上、地下生物量呈幂函数生长关系，地上生物量所占比例高于地下生物量，随株高增大老龄枝所占比例呈升高趋势，而叶、新生枝和地下生物量所占比例呈降低趋势。利用冠幅直径、高和冠幅体积构建的柠条地上、地下及全株生物量的模型较好，小珠和中株建立的估测模型为二次函数，大株建立的估测模型为幂函数，所筛选出来的3个株高最优生物量模型总相对误差（RS）范围为-3.9~-18.08，平均相对误差绝对值（RMA）范围为10.12~18.67，满足要求。

Biomass Allocation Pattern and Estimation Model Building of Caragana korshinskii with Different Plant Heights

Caragana korshinskii is one of the important sand-fixation plants in loess plateau ecosystem. The biomass allocation patterns of Caragana korshinskii with different plant heights were analyzed and the estimation model of above-ground, below-ground and whole plant biomass using simple indicators were simultaneously built. Results showed that the proportion of above-ground biomass was ordered as older branch > leaf > new branch. The proportion of older branch biomass increased with increasing cluster height, while leaf and new branch biomass decreased. The underground biomass of Caragana korshinskii decreased along with the increase of soil layers. Root biomass mainly located in 0~30 cm soil layer, especially 0~5 cm, and the proportion of underground biomass differed from different plant heights in the same soil layer. The proportion of older branch biomass increased with the increase of plant height, while leaf, new branch and underground biomass were decreased. In addition, optimal estimation model was built using crown width diameter (C), height (CH) and crown width volume (V). Estimation model built with small-and medium-sized plants presented quadratic function, while estimation model built with large plants showed exponential function. The RS and RMA ranges of the optimal biomass estimation model were-3.9~-18.08 and 10.12~18.67.