【作者】 王志强；

【导师】 刘建全； 邓建明；

【作者基本信息】 兰州大学 ， 生物学·生态学， 2014， 博士

【摘要】 代谢生态理论(Metabolic Theory of Ecology)认为植物个体的代谢速率(包括呼吸异化速率和光合同化速率)与个体大小的3/4次方呈正比。自该理论提出以来,其异速指数(allometric exponent) 3/4是否具有普适性却受到了极大的挑战。随后,代谢理论创始人Brian J. Enquist等对该理论进行了修正并认为对于植物小个体其代谢速率与个体大小间的异速指数为1,而对于大个体其异速指数为3/4。但其修正后的理论预测是否具有普适性尚不得而知。本研究以云杉9个分类群幼苗为例,通过系统地测定其地上、地下呼吸速率,年均净生产力、叶生物量以及总生物量来研究各特性相互间的异速比例关系(allometric scaling relationship)。结果表明:1)在异化速率方面,云杉属植物9个分类群经环境温度修正的平均单株地上、地下呼吸速率与相应生物量的异速指数分别为0.869和0.809,两者的异速指数均介于代谢异速理论对植物小个体的理论预测值(1)和植物大个体的理论预测值(3/4)之间;2)在同化速率方面,平均单株叶生物量与平均单株年净生产力的异速指数为1.191,平均单株叶生物量与其平均总生物量的异速指数为0.983,两者的异速指数非常符合代谢异速理论对植物小个体代谢速率指数为1的预测;3)不论是植物个体平均地上生物量与地下生物量间的异速指数(1.074),还是经温度修正的平均单株地地上呼吸速率与地下呼吸速率的异速指数(1.154)均很接近理论预测值1,这表明植物个体在没有环境胁迫的条件下,其地上、地卜的物质能量分配应该遵循等速分配原则;4)另外,本研究通过对该云杉属植物9个分类群的自然群落成年树木进行分析,发现其年净生产力与个体大小间的异速指数为1,与代谢理论预测值一致。这些研究结果为代谢理论体系的进一步发展提供了非常重要的理论参考价值。人们通常认为大气中二氧化碳浓度升高是导致全球气候变暖的主要原因之一。因此,如何提高生态系统生产力以及生态系统同化效率日益成为学者们关注的热点。其中,有效方法之一是通过评估不同物种生长季碳同化效率并且为植树造林或生态恢复筛选出具有较高碳同化效率的优势物种,从而相对减少自然生态系统对大气CO2的排放量,增加对大气CO2的吸收同化。本研究基于代谢异速理论,以及直接测定的整株植物瞬时净光合速率和暗呼吸速率;建立了直接预测不同植物物种整个生长季碳同化效率的模型体系。我们利用如上所述云杉属植物9个分类群的整体光合、呼吸速率、年净生产力以及生物量等测定指标,对所建立模型体系中的4个重要假设进行了很好的检验:(ⅰ)二氧化碳通量及能量与个体大小的1次方呈正比,(ⅱ)整株净光合速率、总光合速率以及年净生产力与叶生物量呈正比;(ⅲ)无论是整株瞬时净光合速率、暗呼吸速率,还是总生长速率的异速关系都与温度无关;(ⅳ)瞬时碳同化效率与生长季碳同化效率呈正比关系;且在不同物种中,通过瞬时碳同化效率能够预测生长季碳同化效率。此外,云杉9个分类群之间的瞬时碳同化效率与生长季碳同化效率存在显著差异,且欧洲云杉具有最高的生长季碳同化效率,而天山云杉生长季碳同化效率最低。本研究的理论模型体系和实验方法对评估其他物种生长季碳同化效率以及生态系统的生产力和同化效率具有一定的理论指导意义与实践应用价值。此外,氮、磷元素作为植物代谢化学反应过程中所必需的两种重要元素,且日益受到研究者的广泛关注。植物氮、磷元素的投资策略随着物种生长的差异而变化,同时,遵循基本的化学计量法则。本研究通过测定云杉属植物9个分类群幼苗各组织(根、茎、叶)以及整株碳氮、磷元素,分析氮、磷元素在生物体各组织器官以及整株水平代谢异速关系。研究结果表明:1)各组织器官以及整株碳元素与相应组织器官以及整株氮、磷元素的1次方呈正比;2)各组织器官以及整株呼吸速率与相应组织器官以及整株氮、磷元素的1次方呈正比;3)各组织器官以及整株氮元素与相应各组织器官以及整株磷元素的1次方呈正比。总之,本研究结果并不支持经典的化学计量生长模型,但对化学计量生长模型的进一步补充做出了重要贡献并具有一定的理论指导意义。更多还原

【Abstract】 Metabolic Theory of Ecology (MTE) that describes the relationship of metabolic rate (including: assimilation rate and alienation rate) of plant individuals and body size follows a constant proportional relationship. The allometric exponent has been vigorously debated on Metabolic Theory of Ecology for many years. To test prior theoretical predictions on allomeric relationships among biological traits, a total of nine Picea taxa seedlings were used here to measure aboveground and underground respiration rate, annual net primary productivity, leaves and whole-plant biomass,respectively. Our results showed that 1) in alienation, temperature-corrected average aboveground and underground respiratory rates per plant scaled as 0.869,0.809-power of corresponding biomass per plant respectively, both of which significantly deviated from the three-quarters scaling law predicted by allometric scaling relationship; 2) in assimilation, scaling exponent of average annual net primary productivity per plant versus average leaves biomass per plant was 1.191.Average leaves biomass per plant scaled nearly isometrically (scaling exponent =0,983) with average whole-plant biomass per plant. Both of the allometric exponents mentioned above were close to theoretical prediction value of 1 for small plants; 3)the scaling exponent of average aboveground biomass per plant versus underground biomass per plant (1.074) and temperature-corrected aboveground respiration per plant versus underground respiration rate per plant (1.154) were consistent with the theoretical predictions value of 1, which indicated that the material and energy distribution of aboveground and underground for plant individual were complied by isometric distribution theory without environmental stress. Additionally, we also found that the relationship of annal net productivity per plant and body size scaled nearly 1. These results may provide theoretical references for the evolution of models of metabolic theory.It is generally accepted that increasing CO2 atmospheric levels contribute to global climate change. Accordingly, considerable attention has been paid to how ecosystem productivity and ecosystem assimilation efficiency (EAE) increase naturally. One method is to select species with high seasonal carbon assimilation efficiency (TECA) for reforestation or ecosystem reclamation and then evaluate the TECA of individual species. Here, we developed a theoretical framework based on the metabolic scaling theory to predict the whole growth seasonal carbon assimilation efficiency by directly measuring the whole-plant instantaneous net photosynthetic and dark respiratory rates. Four pivotal predictions of this framework were evaluated using seedlings of nine Picea taxa: (i) the flux rates of CO2 and energy are predicted to scale proportionally (one-to-one) as a function of plant size; (ii) the whole-plant net and gross photosynthetic rates and the net primary productivity are predicted to be directly proportional to the leaf mass; and (iii) these scaling relationships will be independent of temperature regardless of the instantaneous net photosynthetic rate,the instantaneous dark respiratory rate, or the overall growth rate; and (iv) TECA is predicted to conform to an isometric scaling relationship with respect to instantaneous efficiency of carbon assimilation (IECA) such that the latter can be used to predict the former across diverse species in practice. We found that the absolute values of IECA and TECA significantly differed among the nine taxa, with both IECA and temperature-corrected IECA being highest for P. abies and lowest for P. schrenkiana.Our data indicated that the theoretical framework can be used to access seasonal carbon assimilation efficiency of other plant species and can be used to estimate ecosystem productivity and assimilation efficiency.As essential elements for metabolic reactions, both nitrogen and phosphorus are of particular interesting for researchers. Plant investment in nitrogen relative to phosphorus varies with differences in physiological growth strategies among species,while it may follow fundamental stoichiometric rules. In this study, nitrogen and phosphorus contents of roots, stems, leaves and whole plant for seedlings of nine Picea taxa were used to test scaling relationships between these contents and the corresponding organs carbon contents and respiratory rate. Our results demonstrated that 1) the scaling of exponent nitrogen and phosphorus to carbon is not deviating from 1; 2) respiratory rate scales approximately isometrically with nitrogen and phosphorus and 3) isometric scaling of nitrogen to phosphorus per plant is observed in all data. Taken together, these findings provide no support for classic stoichiometric growth model, but gain new insights into the stoichiometric growth model.更多还原