马尾松与阔叶树种混合凋落叶分解过程中总酚和缩合单宁的变化

Changes of total phenols and condensed tannins during the decomposition of mixed leaf litter of Pinus massoniana and broad-leaved trees

采用凋落物分解袋法,研究四川低山丘陵区马尾松与檫木、香椿、香樟3种阔叶树种的混合凋落叶及纯马尾松凋落叶分解过程中总酚和缩合单宁的变化特征.设置马尾松∶檫木质量比为6∶4、7∶3、8∶2,马尾松∶香椿质量比为6∶4、7∶3、8∶2,马尾松∶香樟质量比为6∶4、7∶3、8∶2混合处理.结果表明:经过180 d的分解,纯马尾松凋落叶缩合单宁的降解率为84.4%,混合凋落叶缩合单宁的降解率均高于纯马尾松凋落叶.在所有组合中,马尾松∶香樟6∶4混合凋落叶的缩合单宁和总酚降解率最高,分别为90.3%和68.6%,凋落叶的混合促进了马尾松凋落叶缩合单宁和总酚的分解.随着分解时间的延长,马尾松与3种阔叶凋落叶所有混合处理缩合单宁的降解率均呈现先上升后趋于稳定的趋势.而纯马尾松凋落叶、马尾松∶香樟(7∶3)和马尾松与香椿的所有混合处理总酚的降解率呈现在分解前90 d上升此后下降的趋势;马尾松与檫木的所有混合处理及马尾松∶香樟6∶4和8∶2混合处理总酚降解率呈现上升趋势.混合凋落叶分解过程中,单宁和总酚的变化特征还与凋落物基质质量、凋落物分解相关酶(多酚氧化酶、过氧化物酶、亮氨酸氨基肽)的活性有关.

A field litterbag experiment was conducted to investigate dynamics of total phenols and condensed tannin in the mixed leaf litter of Pinus massoniana（ P） with other three broad-leaved species,i.e.,Sassafras trumu（ S）,Cinnamomum camphora（ C）,Toona sinensis（ T） during decomposition in low hilly lands,Sichuan Province,China. The mass ratio of P. massoniana ： S.trumu（ PS） was 6： 4,7： 3,8： 2,P. massoniana ： C. camphora（ PC） was 6： 4,7： 3,8： 2 and P.massoniana ： T. sinensis（ PT） was 6： 4,7： 3,8： 2,respectively. The results showed that the degradation rate of condensed tannin in pure P. massoniana litter was 84.4%,being significantly lower than that in the mixed litters after 180 d. The degradation rate of condensed tannin and total phenols were the highest in PC 6： 4,with 90.3% and 68.6%,respectively. The mixed litters promoted the decomposition of condensed tannin and total phenols in the P. massoniana litter. With decomposition time,the degradation rate of condensed tannin in mixed litters between P. massoniana and broadleaved species initial increased,and then remained stable. The degradation rate of total phenols in pure P. massoniana litter,PT 7： 3 and all the PC treatments increased significantly and then decreased during the 90 d decomposition. The degradation rate of total phenols in all the PS,PT6： 4 and 8： 2 treatments increased with the decomposition time. The dynamics of total phenols and condensed tannin were closely related to litter quality,and the enzyme activities of polyphenol oxidase,peroxidase and leucine aminopeptidase.