鄂西南亚高山湿地泥炭藓的生长与分解

Growth and decomposition characteristics of Sphagnum in a subalpine wetland, southwestern Hubei, China

泥炭藓(Sphagnum)是湿地土壤碳的重要来源,在土壤碳累积过程中发挥着关键作用,但有关亚热带湿地泥炭藓生长与分解的研究鲜有报道。该研究选择鄂西南亚高山泥炭藓湿地为研究区域,原位开展不同微生境泥炭藓的生长及其凋落物的分解实验,室内测试凋落物的化学成分,探讨亚热带亚高山湿地泥炭藓的生长与分解规律。结果表明:泥炭藓在自然状态生长12个月后,丘上和丘间两种微生境下泥炭藓的平均高度增长量分别为2.9和2.7cm,对应的净生产量分别为270.94和370.88g·m–2,生长时间与微生境对泥炭藓的高度增长量及净生产量均有显著影响,且两者之间存在交互作用,但是两种微生境下泥炭藓的生长变化过程不同;两种微生境下泥炭藓的平均生长速率(2017年7–10月)为0.33 mm·d–1,其生长速率高于寒温带地区。另外,分解时间对泥炭藓的分解量有显著影响,其残留率随时间增加表现为先减少后增加的趋势。12个月后,丘间、丘上和水坑3种微生境下最终残留率分别为100.67%、90.54%和85.63%。凋落物中碳含量、碳氮比和多酚含量相比初始值均有所下降,氮含量则为增加。同时,微生境对凋落物分解的影响取决于分解时间。分解3个月时,微生境之间凋落物的分解量差异显著,其他时间段差异不明显。

Aims We investigated the growth and decomposition of Sphagnum,a principal plant involved in peat accumulation in wetlands,in subtropical wetlands.Methods We selected a Sphagnum-dominated wetland in southwestern Hubei Province as the study area.In situ growth and litter decomposition experiments in different microhabitats were carried out,and the chemical composition of litter was measured in laboratory to examine the processes of its growth and decomposition.Important findings The average height of Sphagnum in hummock and hollow were 2.9 and 2.7 cm,and the net production was 270.94 and 370.88 g·m–2,respectively,after 12 months.Growth time and microhabitats significantly affected on the height growth and the net production,and there was an interaction between time and microhabitats.However,the growth trend in two microhabitats was significantly different.The average growth rate of Sphagnum under the two microhabitats(July to October 2017)was 0.33 mm·d–1,which was higher than that in the cold temperate zone.In addition,the decomposition time had an significant effect on the decomposition amount of Sphagnum,and the residual rate decreased first and then increased with time.By the end 12-month period,the final residual rates in hollow,hummock and pool were 100.67%,90.54%and 85.63%,respectively.The content of carbon(C),carbon nitrogen(N)ratio(C:N)and polyphenols in the litters decreased,while the nitrogen content increased.During the first 3 months of decomposition,a significant difference of decomposed litter was found between the microhabitats,but no significant difference later on.