黄顶菊凋落物的分解特性及其对模拟氮沉降的响应

发布时间：2017-12-26 20:13

本文关键词：黄顶菊凋落物的分解特性及其对模拟氮沉降的响应　出处：《沈阳农业大学》2017年硕士论文　论文类型：学位论文

【摘要】：生物入侵和氮沉降加剧作为两种全球变化因子,可能共同影响入侵植物凋落物分解过程。了解植物入侵和氮沉降单独或二者对凋落物分解的复合影响,有助于揭示全球变化背景下的植物入侵机理,并为降低入侵植物危害提供理论依据。本试验先以入侵植物黄顶菊(Flaveria bidentis)和共生本地植物狗尾草(Setaria viridis)叶片凋落物为对象,采用凋落袋法研究了氮添加和埋土处理对其残留率、含C量、含N量和C/N的影响。由于凋落物的物种组成和凋落物的类型是影响凋落物分解的主要因素,并且它们的影响受到外部养分可利用性的调控,进一步我们研究了氮添加是否影响入侵植物黄顶菊不同器官凋落物(叶、细根和茎)的分解速率和养分释放特征。结果显示,施氮明显降低了黄顶菊叶片凋落物的分解速率,施氮处理叶片黄顶菊凋落物的分解常数k值为1.68,显著的小于对照2.26,而对狗尾草凋落物分解有一定的促进作用,但差异不显著。埋土处理对两种植物凋落物分解均表现显著促进。埋土以及埋土和施氮共同处理两个物种叶片凋落物的分解均有显著的促进作用,埋土处理部分抵消了氮添加对黄顶菊凋落物的抑制作用。特别地,倍增氮沉降单一因素并未影响黄顶菊叶片凋落物N固持,而埋土和二者综合作用显著促进了N固持。一方面,施氮处理对入侵植物凋落物的分解影响表现出器官差异,倍增氮沉降抑制了叶凋落物的分解,其叶凋落物的分解速率比对照减少了 25%,但是对其它器官凋落物的分解速率没有影响。这一差异导致在施氮后入侵植物和本地植物叶凋落物的分解常数趋同。因此,植物器官对氮沉降响应的差异远大于物种之间的差异。另一方面,施氮引起凋落物质量的改变,但是没有导致凋落物更多的氮释放,表明施肥水平通过改变分解者养分可利用性对分解的直接影响显著大于通过改变凋落物的质量的间接影响。总之,氮素沉降水平倍增以及入侵种凋落物不同管理方式(埋土或土表)均可影响凋落物的分解速率和养分循环,但存在物种差异,这种差异主要由于凋落物质量的差别。未来氮沉降情形下,黄顶菊入侵地凋落物的较低的分解速率常数会导致土壤碳库增加,促进其成功入侵。伴随着氮沉降水平的增加,地下土壤碳库在入侵植物与氮循环的正反馈方面将变的更加明显。鉴于埋土对黄顶菊凋落物分解和养分释放的促进作用,可采取清除凋落物等的方法阻断植物-土壤正反馈机制,实现对入侵植物的控制。
[Abstract]:Biological invasion and nitrogen deposition are two global change factors, which may affect the decomposition process of invasive plant litter together. Understanding the combined effects of plant invasion and nitrogen deposition alone or two on litter decomposition is helpful to reveal the mechanism of plant invasion in the context of global change, and to provide a theoretical basis for reducing the harm of invasive plants. The first test in invasive plant Flaveria bidentis (Flaveria bidentis) and symbiosis of native plants (Setaria viridis) johnswort leaf litter as the object, studies the influence of soil nitrogen addition and the residual rate, C content, N content and C/N using the litter bag method. Because of the type species and litter litter are major factors affecting litter decomposition, and their influence can be controlled by the external nutrient, we further studied whether the addition of nitrogen effects of invasive weed flaveriabidentis in different organs (leaf litter and fine root and stem) of the decomposition rate and nutrient release characteristics. The results showed that nitrogen fertilizer significantly reduces the decomposition rate of flaveriabidentis leaf litter, decomposition constant k of nitrogen in leaves of Flaveria bidentis litter was 1.68, significantly less than the control 2.26, while the Setaria litter decomposition has certain stimulative effect, but the difference was not significant. The buried soil treatment significantly promoted the litter decomposition of the two plants. Were buried, buried soil decomposition and nitrogen treatment of two species of leaf litter significantly promoted, buried soil treatment partially offset the inhibitory effect on nitrogen addition of flaveriabidentis litter. In particular, double single factor did not affect flaveriabidentis leaf litter nitrogen deposition and N immobilization, the comprehensive effect of soil and buried two significantly promoted N holding. On the one hand, the effect of Nitrogen Application on the decomposition of invasive plants showed different organs. The doubled nitrogen deposition inhibited the decomposition of leaf litter, and the decomposition rate of leaf litter decreased by 25% compared with the control, but it had no effect on the decomposition rate of other organs. This difference leads to the convergence of decomposition constants of invasive plants and local plant leaf litter after nitrogen application. Therefore, the difference in the response of plant organs to nitrogen deposition is far greater than the difference between species. On the other hand, nitrogen application caused changes in litter quality, but did not cause more nitrogen release from litter. It indicated that the direct effect of fertilization level on decomposition was significantly greater than that by changing litter quality indirectly. In conclusion, different levels of nitrogen deposition and different management modes of buried species and litter can affect litter decomposition rate and nutrient cycling, but there are species differences. The difference is mainly due to the difference of litter quality. The future of nitrogen deposition conditions, the decomposition rate constants of low F.bidentis invasion of litter will lead to increased soil carbon pool, promote its successful invasion. With the increase of nitrogen deposition level, the underground soil carbon pool will become more obvious in the positive feedback of the invasive plants and nitrogen cycle. In view of the fact that buried litter decomposition of flaveriabidentis and nutrient release promotion method can take a clear litter blocking plant soil positive feedback mechanism, realize the control of invasive plants.
【学位授予单位】：沈阳农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q948

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