首页 > 分享 > 模拟氮沉降对北京东灵山辽东栎群落林下植物物种多样性的影响

模拟氮沉降对北京东灵山辽东栎群落林下植物物种多样性的影响

花匠小妙招
2025-09-17 17:41

摘要：

氮沉降是驱动生物多样性变化的重要因素之一。一般认为氮沉降会改变物种多样性, 而且在外源氮添加条件下, 禾草类植物和落叶灌木比杂类草和常绿灌木更具竞争优势。不过该结论更多是从高寒草甸和荒漠草原等生态系统中得到, 主要是针对同一生活型内植物之间的竞争关系, 不涉及不同生活型植物之间的相互作用, 并且由于草原和草甸等生态系统没有明显的垂直结构, 同一层次中植物的高度差异较小, 有可能高估了光照因素对植物的作用。因此从森林生态系统入手, 可以进一步阐述不同生活型植物对氮沉降的响应。本文以我国北方典型的落叶阔叶林——辽东栎(Quercus wutaishanica)林为研究对象, 设置CK (0 kg N·ha -1·yr -1)、N50 (50 kg N·ha -1·yr -1)和N100 (100 kg N·ha -1·yr -1) 3个梯度氮添加实验, 模拟氮沉降对温带森林生物多样性的影响。8年连续的氮添加实验结果显示: (1)氮添加显著降低了林下植物的物种丰富度和多样性, 改变了群落的物种组成; (2)氮添加提高了灌木植物的物种丰富度和多样性; 降低了草本植物的丰富度; (3)氮添加降低了禾草类植物的重要值, 提高了杂类草的重要值。该研究表明, 长期氮添加会显著改变林下植物的物种组成, 不同生活型植物对氮添加的响应亦有所差别。造成该现象的原因可能是由土壤环境变化(如养分含量提高, pH值下降)和植物获取光照能力强弱(如灌木植物获取光资源要多于草本植物)导致。

关键词: 氮沉降, 物种丰富度, 辽东栎, 林下植物, 物种多样性

Abstract

Nitrogen deposition is one of the major driving factors for biodiversity. Generally speaking, graminoids and deciduous shrubs compete more for nitrogen than forbs and evergreen shrubs. However, previous studies have mainly focused on a single life-form of plants in alpine meadows or desert steppes, ignoring the range of different life-forms across different habitats. Furthermore, there is no obvious canopy or vertical structure in these ecosystems that might exacerbate light limitation. Hence, there need to be more nitrogen experiments in other more complicated ecosystems (e.g. forest ecosystem) to better understand how nitrogen affects understory plants. We conducted an 8-year N fertilization experiment with three treatment levels (0 kg N·ha -1·yr -1, 50 kg N·ha -1·yr -1, 100 kg N·ha -1·yr -1) in the Quercus wutaishanica forest at Mt. Dongling, Beijing to study the response of temperate forest understory plants to nitrogen deposition. We found that: (1) Nitrogen addition reduced the species richness and biodiversity of understory plants and changed the species composition and community structure significantly. (2) Nitrogen addition increased richness of the shrub layer, but decreased richness of the herbaceous layer. (3) Graminoids responded negatively to nitrogen deposition, while forbs were positively affected. The study shows that richness and species composition change differently in response to nitrogen deposition for different life-forms of plants. In fact, the entire community of understory plants may shift in response to a change in soil resources (e.g. increase in nutrient contents and decrease in pH) and light availability (e.g. shrubs can access light easier than herbs).

Key words: nitrogen deposition, species richness, Quercus wutaishanica, understory plants, biodiversity