9种典型荒漠植物生态化学计量学特征分析

Ecological Stoichiometric Differences of Nine Typical Eremophyte Species

化学计量学是研究生态过程中能量平衡和多重化学元素平衡的科学,能够定量化研究活有机体重要组成元素碳（C）、氮（N）、磷（P）之间的关系,有助于解决植物和生态系统养分供应与需求等方面的难题为解决生态系统养分供求与循环问题提供了新思路。化学计量学已成为研究生态系统元素平衡和生物地球化学循环的重要手段之一。为了厘清极端环境条件下荒漠植物在逆境适应与元素循环的反馈能力,对东阿拉善-西鄂尔多斯荒漠生态系统中9种优势植物霸王（Sarcozygium xanthoxylon）、胡杨（Populus euphratica）、四合木（Tetraena mongolica）、白刺（Nitraria tangutorum）、蒙古扁桃（Amygdalus mongolica）、沙冬青（Ammopiptanthus mongolicus）、沙拐枣（Calligonum mongolicum）、细枝岩黄芪（Hedysarum scoparium）和沙棘（Hippophae rhamnoides）根、茎、叶的C、N、P含量和生态化学计量学特征进行了分析。结果表明：（1）9种荒漠植物根、茎、叶的C、N、P含量的均值分别为：418.96 mg·g^-1、15.07 mg·g^-1、1.10 mg·g^-1,460.88 mg·g^-1、12.99 mg·g^-1、1.03 mg·g^-1,435.07 mg·g^-1、23.40 mg·g^-1、1.18 mg·g^-1。根、茎、叶的C∶N∶P化学计量比分别为381∶14∶1、447∶13∶1和369∶20∶1。表明其C的相对过量和P元素的限制性。（2）植物根部的C储备能力较弱,与其处于荒漠生态系统土壤贫瘠,日照强,年降水量较低有关。（3）四合木的N∶P（9.45）计量学较全球陆生植物（12.6）、中国陆生植物（16.3）中国北方典型荒漠及荒漠化地区植物（15.8）显著偏低,表现出我国特有孑遗珍稀植物四合木化学计量学特征的独特性。（4）与已有的荒漠植物化学计量学研究结果相比,9种荒漠植物根、茎、叶N含量均显著偏高,茎和叶P含量显著偏低,根的P含量无显著差异。生物与环境的协同进化,使得荒漠植物在温度逆境、干旱胁迫、营养限制、物质代谢和辐射损伤的条件下,经过长期的进化适应形成了自身独特的生理生态和生态化学计量特征。该研究结果可为我国西北荒漠区植物化学元素循环以及生物多样性保护中限制性营养的判定与维护生态系统元素平衡提供案例借鉴。

Chemometrics is normally utilized for studying the energy balance and mass balance in ecological process. It can be used to quantify the relationship between C,N and P in living organisms. In recent years,some studies indicate that the introduction of chemometrics avails the solution of various scientific issues associated with the nutrient demand and supply of plants and ecosystems. In other words,chemometrics provides a novel methodology for addressing issues in terms of nutrient demand,supply and cycle of ecosystem. Chemometrics has become as one of the major methods in studying the balance of chemical elements of ecosystem and the biogeochemical cycle.In order to elucidate the adaptation ability in adversity of eremophytes and clarify how chemical element cycle under extreme environmental conditions,this paper carried out a research on nine dominant eremophytes in desert ecosystem in the east Alxa-west Erdos,including Sarcozygium xanthoxylon,Populus euphratica,Tetraena mongolica,Nitraria tangutorum,Amygdalus mongolica,Ammopiptanthus mongolicus,Calligonum arborescens,Hedysarum scoparium and Hippophae rhamnoides,to figure out the contents of C,N and P in their roots,stems and leaves,and to analyze the characteristics of ecological stoichiometry. The results are as follows：（1） The average contents of C,N and P in roots,stems and leaves of the nine eremophytes were 418. 96 mg · g-1,15. 07 mg·g^-1 and 1. 10 mg · g-1;460. 88 mg·g^-1,12. 99 mg·g^-1 and 1. 03 mg·g^-1; and 435. 07 mg·g^-1,23. 40 mg·g^-1 and 1. 18 mg·g^-1,respectively. The stoichimetric ratios of C∶ N∶ P were 381∶ 14∶ 1,447∶ 13∶ 1 and 369∶ 20∶ 1 respectively. These figures showed that the amount of C in these nine eremophytes was excessive,but that of P was limited;（2） The reserve capacity of C in roots of eremophytes was low due to the infertile soil,strong sunshine and low annual precipitation in the desert ecosystem;（3） The average stoichimetric ratio of N∶ P of global terrestrial plants is 12. 6,of that in China is 16. 3,and of plants in typical desert and desertification areas in north China is 15. 8. Compared with them,the stoichimetric ratio of N∶ P of T. mongolica was significantly lower and only 9. 45. This result showed the peculiarity of chemometrics of T. mongolica,and it is one of endemic and rare plants in China;（4） Compared with the available results of the studies on chemometrics of eremophytes,the contents of N in roots,stems,and leaves of these nine eremophytes were significantly higher,and the contents of P in stems and leaves were significantly lower. There was no remarkable difference in the content of P in roots. The long-term biological and environmental co-evolution allows eremophytes to establish their unique stoichiometric characteristics under specific environmental stress,such as extreme temperature,drought,nutrient limitation and radiation damage. The results of this study provide a reference for analyzing the cycle of chemical elements in eremophytes growing in desertification areas in northwest China,and also provide a case for determining the limit nutrient at the respect of conservation of biological diversity.