不同入侵程度肿柄菊生态化学计量特征

Ecostoichiometric characteristics of Tithonia diversifolia with different invasion degrees

  • 摘要: 【目的】研究不同入侵程度下肿柄菊植株不同器官及根际土壤化学计量特征,剖析肿柄菊资源利用和分配策略,为肿柄菊入侵防控提供理论参考。【方法】在云南省普洱市思茅区郊区公路边选取有肿柄菊入侵至少4年的研究样地,设15个试验区,包括5个重度入侵区(肿柄菊盖度占70%以上)、5个中度入侵区(肿柄菊盖度占30%~70%)和5个轻度入侵区(肿柄菊盖度占30%以下),分别采集肿柄菊根、茎、叶样品及根际土壤样品,检测植株和土壤中全磷(TP)、全氮(TN)和有机碳(SOC)含量,并分析化学计量特征。【结果】随入侵程度的增加,肿柄菊生境土壤TN和SOC含量呈显著降低趋势(P<0.05,下同),而TP含量无显著变化(P>0.05,下同);从轻度入侵到重度入侵,TN含量下降54.2%,SOC含量下降53.1%,肿柄菊入侵地土壤SOC和TN贫乏。3种入侵程度的肿柄菊各器官TP和TN含量均为叶>根>茎,SOC含量为根>叶>茎。重度入侵有利于肿柄菊植株TP含量积累,轻度入侵有利于肿柄菊茎TN含量积累。从轻度入侵到重度入侵,肿柄菊根、茎C∶N显著升高,根、茎C∶P显著降低,茎N∶P显著降低;同一入侵程度的肿柄菊C∶N和C∶P均为茎>根>叶;N∶P在轻度入侵为叶>茎>根,在中度和重度入侵为叶>根>茎。入侵程度对肿柄菊TN和TP含量及C∶N、N∶P具有显著或极显著影响(P<0.01,下同),不同器官对肿柄菊SOC、TN和TP含量及C∶N、C∶P、N∶P均具有极显著影响;器官与入侵程度交互作用仅对N∶P有极显著影响,对其他指标无显著影响。肿柄菊根、茎与土壤的TP、TN和SOC含量及化学计量比之间部分存在显著或极显著相关性。【结论】肿柄菊入侵对研究样地的土壤产生一定影响,土壤的改变同时反馈于肿柄菊。肿柄菊将N、P元素更多分配给叶,C元素更多分配给根,生长受到N元素限制;肿柄菊的根和叶具有相对快速的生长能力,以扩张种群、增大入侵性。

     

    Abstract: 【Objective】In this paper,the stoichiometric characteristics of different organs and rhizosphere soil of Tithonia diversifolia plants with different invasion degrees were investigated,and the resource utilization and allocation strategies of T. diversifolia were analyzed,which provided theoretical reference for the prevention and control of T. diversifolia invasion. 【Method】A study site with at least 4 years of T. diversifolia invasion was selected along the suburban highway in Simao District,Pu’er City,Yunnan Province. Fifteen experimental areas were set up, including five severely invaded areas(T. diversifolia coverage>70%), five moderately invaded areas(T. diversifolia coverage 30%-70%),and five mildly invaded areas(T. diversifolia coverage<30%). Samples of roots, stems and leaves of T. diversifolia and its rhizosphere soil were collected to detect the contents of the total phosphorus(TP), total nitrogen(TN),and soil organic carbon(SOC),and to analyze the stoichiometric characteristics. 【Result】With the increase of invasion degree,the contents of TN and SOC in soil of T. diversifolia habitat decreased significantly(P<0.05,the same below), while the content of TP did not change significantly(P>0.05,the same below). From mild to severe invasion, the content of TN decreased by 54.2%, and the content of SOC decreased by 53.1%, indicating that the soil in the invaded areas was poor in SOC and TN. The contents of TN and TP in different organs of T. diversifolia with three degrees of invasion were leaf>root>stem,and the content of SOC was root>leaf>stem,indicating that severe invasion was beneficial to the accumulation of TP content in the plants of T. diversifolia,and mild invasion was beneficial to the accumulation of TN content in the stems of T. diversifolia.As the degree of invasion increased,the C∶N value of root and stem increased significantly,the C∶P value of root and stem decreased significantly,and the N∶P value of stem decreased significantly. The C∶N,C∶P values of T. diversifolia were stem>root>leaf;N∶P value in mild invasion was leaf>stem>root,in moderate and severe invasion was leaf>root>stem. The degree of invasion had significant or extremely significant(P<0.01,the same below) influence on the contents of TN and TP and C∶N and N∶P values, and different organs had extremely significant influence on the contents of SOC, TN and TP and C∶N, C∶P and N∶P values.The interaction between the organs and the degree of invasion only had extremely significant influence on N∶P, and had no significant influence on other indicators. There were significant or extremely significant correlations between the contents of TP, TN and SOC and stoichiometric ratios of roots, stems, leaves and soil of T. diversifolia. 【Conclusion】The invasion of T. diversifolia has certain influence on the study of local soil, and the change of soil also gives feedback to T. diversifolia. The N and P elements are more allocated to the leaves, and the C element is more allocated to the roots, and the growth is limited by the N element. The roots and leaves of T. diversifolia have relatively rapid growth ability to expand the population and increase the invasiveness.

     

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