荒漠草原人工草地豆科与禾本科牧草生物量分配模型研究

利用荒漠草原人工草地豆科与禾本科牧草地上和地下生物量及根长数据,分析并建立生物量分配比例模型。结果表明:两种牧草地上-地下生物量分配模型明显不同,豆科牧草单株生物量明显高于禾本科牧草,地上-地下生物量具有明显的线性关系,拟合参数R2优于禾本科牧草,符合等速生长模型,而禾本科牧草地上-地下生物量呈幂数异速生长关系,异速生长模型的相关系数均在0.368 0以上,与WBE预测模型3/4次幂函数出现偏差;豆科牧草根冠比(R/S)为0.75,接近于中国草地R/S均值0.78,禾本科牧草R/S(1.73)明显高于中国草地R/S均值,表明豆科牧草倾向于将更多的生物量分配到地上,禾本科牧草将更多的生物量分配到地下;不同大小个体的两种牧草R/S均存在明显的可塑性,表现出种内和种间差异,均未出现最优分配理论调节地上-地下生物量分配模式;豆科牧草随个体的增大R/S逐渐变小,禾本科牧草随个体的增大R/S逐渐变大;利用牧草根长拟合其生物量模型,最优预测模型为三次曲线,相关系数在0.511 2~0.906 0。

Allocation Models of Biomass of Legume and Grass Forages of Artificial Grassland in Desert Steppe

Analyzed and established the allocation of above- and below-ground biomass allocation models using legume and grass forages aboveground, underground biomass and root length data of artificial grassland in desert steppe .The results showed that above- and below-ground biomass allocation of two forages were obviously different. Legume forages biomass were significantly higher than grass forages, fitting parameters R2 was better than that of grass forages which means the allocation patterns between above-and belowground biomass were similar at both levels and indicated an isometric allocation relationship between above- and below-ground biomass. However, relationships between the root and the shoot of grass forages characterized by the allometry model, their correlation coefficients were larger than 0.3680 with a bias against the predicted modes of WBE. Legume forages allocated more biomass into roots with root / shoot (R/S) ratio of 0.75 which was close to the average of R/S ratio of China(0.78), On the contrary, grass forages allocated more biomass into shoots with R/S ratio of 1.73 which was significantly higher than 0.78. Two different size of individual forages R/S ratio were obvious plasticity, showed the intraspecific and interspecific differences, and R/S ratio of these legume and grass forages accord with the results predicted with the optimal theory and model. The R/S ratio of legume forages became smaller with the increase of individual, and the trends were opposite in grass forages. The biomass as well as its component were more relevant to root length, and the cubic curve was the optimal predictive model with correlation coefficient between 0.5112 and 0.9060