阔叶红松林不同演替阶段灌木器官的N、P分配特征

Abstract

氮（N）、磷（P）是植物生长发育重要的限制元素，N、P以及N、P间的关系是化学计量学研究的重要内容。植物不同器官对N、P的需求存在差异，因此N、P的分配与权衡对植物的生长发育起到重要的调节作用。为了探究阔叶红松（Pinus koraiensis）林不同演替阶段主要灌木器官的N、P化学计量特征及其分配格局，了解灌木的养分限制因子及其分配策略，在黑龙江凉水国家级自然保护区的阔叶红松林四个演替阶段——白桦（Betula platyphylla）次生林、阔叶混交林、针阔混交林和阔叶红松林内，选取主要灌木种，分析了叶片、枝条、茎干和根的N、P化学计量特征以及异速生长关系。结果发现：灌木不同器官之间的N、P含量差异显著，其中叶的N、P含量均为最高，茎干的N、P含量均为最低。所有器官中，叶的N ： P最高，为7.59；根的N ： P最低，为5.47。灌木叶、茎干、根之间的N ： P存在显著差异，而茎干、根与枝条之间的N ： P没有显著差异。阔叶红松林不同演替阶段对灌木同一器官N、P化学计量的影响不同，灌木叶片的N含量在不同演替中具有显著差异，其他器官的差异不显著；不同演替阶段灌木器官的P含量均无显著差异。在不同演替阶段中各器官的N ： P均小于14，说明N元素是阔叶红松林各演替阶段灌木生长的限制因子，而P对灌木的生长没有起到限制作用。研究表明在不同演替阶段中，N、P的异速生长关系普遍存在于灌木器官中，呈现显著的正相关关系；整体上各器官之间的斜率没有显著差异，说明灌木采取保守分配策略，以此来适应环境和满足自身生长发育的需要。;Nitrogen (N) and phosphorus (P) were important limiting elements for plant growth and development in the nature. N, P and their relationship were essential contents in stoichiometry. Different plant organs had different demands for N and P, therefore the allocation and trade-off of N and P played an important role in the growth and development of plants. In order to explore the N and P stoichiometric characteristics and allocation patterns of shrub organs in different successional stages of the mixed broadleaved-Korean pine (Pinus koraiensis) forest, and to understand the nutrient limiting factors and allocation strategies, the dominant shrub species in four successional stages (secondary birch forest, mixed broad-leaved forest, mixed broadleaved-conifer forest and the mixed broadleaved-Korean pine forest) were selected in Liangshui National Nature Reserve, Heilongjiang. In this study, to research the N and P stoichiometric characteristics and allometric relationship, leaves, twigs, stems and roots of shrubs were collected to analyzed. The results showed that the contents of N and P in different organs were significantly different. In addition, the contents of N and P in leaves were the highest, while those in stems were the lowest among all shrub organs. The N:P ratio of leaves was the highest (7.59), and that of roots was the lowest (5.47). N:P ratio in leaves, stems and roots were significantly different, but N:P ratios in stems, roots and twigs were not significantly different. The effects on N and P stoichiometry of the same organ in different successional stages of the mixed broadleaved-Korean pine forest were different. Specifically, the N content in leaves had a significant difference, though the difference in other organs was not significant. There was no significant difference in P content of shrub organs among the four successional stages. In fact, all of N:P ratios were less than 14, which showed that N was always a limiting factor for shrub growth in different successional stages of the mixed broadleaved-Korean pine forest. However, P had no limiting effect on the growth of shrubs. Our research revealed that the allometric relationship of N and P generally existed in shrub organs in different successional stages, presenting a significantly positive correlation. In general, there was no significant difference among the allometric slopes of shrub organs in the mixed broadleaved-Korean pine forest, indicating that the shrub adopted a conservative allocation strategy to adapt to the environment change and satisfy the needs of its own growth and development.