氮沉降对泥炭地影响的研究进展

Effects of nitrogen deposition on peatland:A review

泥炭地是全球碳循环中的重要碳库,其养分贫乏的环境特征、生态过程和生态功能正受到氮沉降的影响。本文从6个方面就氮沉降对泥炭地生态系统的影响予以综述:(1)泥炭地多受氮限制,氮沉降增加土壤氮含量,改变微生物群落组成,促进细菌数量的增加,提高微生物酶活性,改变泥炭地的土壤环境;(2)在高氮沉降的泥炭地中,泥炭藓对氮的持留能力、传输能力和耐受能力均降低,造成致毒效应,并最终被喜氮的维管植物代替;(3)氮沉降改变了泥炭地氮贫乏的状况,对植被生产力的影响主要以促进为主;(4)氮沉降增加维管植物氮的供应,促进其生长,而使泥炭藓处于光竞争的劣势地位,改变泥炭藓及其与维管植物的种间关系;(5)氮沉降改变植物体内氮磷比,影响苔藓植物的繁殖与更新,导致泥炭地植被物种组成的变化,甚至引发植被演替;(6)氮沉降通过与泥炭地地上和地下生物组分相互作用,促进泥炭地分解,严重威胁着泥炭地的碳库功能。最后,文章指出了目前泥炭地氮沉降研究中存在的一些问题,为泥炭地氮沉降进一步的研究提供参考。

Peatland is an important carbon pool in global carbon cycle. Its oligotrophic environ- ment, ecological processes, and ecological functions are affected by nitrogen deposition. This pa- per reviewed the effects of nitrogen deposition on peatland ecosystems from the following aspects ： （1） the production in peatland is generally nitrogen-limited, while nitrogen deposition can change the peatland soil environment by increasing nitrogen availability, altering microbial com- position, increasing bacterial quantity, and improving enzyme activity ; （2） in high nitrogen dep- osition peatland, the nitrogen interception, translocation, and tolerance abilities of Sphagnum will be decreased, leading to the toxic effect on Sphagnum and its replacement by nitrophilous vascular plants; （3） nitrogen deposition may change the oligotrophic soil environment, and pro- mote the productivity of peatland ; （4） the increase of nitrogen supply may improve the growth of vascular plants, leading to the inferior position of Sphagnum in light competition and the alterna- tion of interspecific relationships between Sphagnum and vascular plants ; （5） nitrogen deposition will change the N/P ratio in plants, and then, affect the reproduction and regeneration of Sphag- num, which will bring about the changes of vegetation species composition, and therefore, vege- tation succession in peatland ; and （6） through the interaction of above- and belowground biologi- cal components, nitrogen deposition will accelerate peat decomposition, and weaken the role of peatland as a carbon pool. Some issues in the present related studies were addressed, and some suggestions for the further researches were offered.