民勤荒漠绿洲过渡带优势植物地上和地下生物量的估测模型

荒漠优势物种生物量的定量测量是荒漠土壤管理的重要依据。为精确估计民勤典型绿洲-荒漠过渡带中优势物种生物量,我们用随机选取的82个10 m×10 m的样方进行优势物种调查。结果显示试验地物种结构简单,而且总盖度仅为16.12%。选取5种荒漠优势物种(白刺(Nitraria tangutorum)、沙拐枣(Calligonum mongolicum)、梭梭(Haloxylon ammodendron)、沙蓬(Agriophyllum squarrosum)和盐生草(Halogeton arachnoideus)),利用全挖法测定其地上和地下生物量。用测定生物量80%的数据分析每一种植物地上和地下干、鲜生物量与其自身的形态参数地径、高度和冠幅之间的相关关系,再利用线性回归分析方法,以相关性显著的形态参数为自变量确定了预测试验地每一优势物种最适宜的地上及地下干、鲜生物量的回归模型。研究结果证实包括地茎(除白刺)和盖度为自变量的回归方程和5种优势荒漠植物的生物量拟合度很好,用测定生物量20%的数据对所有模型进行检验,证实所有生物量的估测模型能够精确预测优势荒漠物种生物量。

ESTIMATION OF ABOVE- AND BELOW-GROUND BIOMASS OF DOMINANT DESERT PLANT SPECIES IN AN OASIS- DESERT ECOTONE OF MINQIN, CHINA

Most desert soil management decisions are based on quantitative measurements of the biomass of thedominant plant species. The biomass of the dominant plant species in a typical oasis-desert ecotone (ODE) ofMinqin was measured in 82 plots ( 10 m × 10 m). The results showed that the distribution and total cover wasapproximately 16.12%. Above- and below-ground biomass of five dominant desert species (Nitraria tanguto-rum, Calligonuum mongolicum, Haloxylon ammodendron, Agriophyllum squarrosum and Halogeton arach-noideu) was measured by excavation. Linear regressions were used to analyze the relationships among all thebiomass components for each plant (fresh and dry weight of above- and below-ground biomass) and the basaldiameter, total height and canopy cover. Best fit models were constructed for each species using 80% of thedata. Our results showed that basal diameter (excluding N. tangutorum) and canopy cover were the best pre-dictors of biomass for all five desert plant species. A validation test using the other 20% of the data not usedfor estimating the regression equations indicated that these equations made accurate predictions of desert plantspecies biomass.