闽江口秋茄红树林凋落物产量及分解动态

于2017年以闽江口粗芦岛秋茄(Kandelia obovata)红树林为研究对象,分别采用凋落物收集框和分解袋法,研究秋茄凋落物产量及其碳(C)、氮(N)、磷(P)含量月动态及凋落叶分解过程中C、N、P含量与水解酶活性.结果表明:①秋茄凋落物年产量为618.79 g·m~(-2)·a~(-1),其中,叶占61.2%,果、枝和花分别占23.7%、10.5%和4.6%.②凋落叶总氮(TN)含量8月显著高于其他月份(p0.05),而TP含量在1—3月显著高于其他月份;C/N在8月显著低于其他月份(p0.05),而C/P及N/P在9月显著升高(p0.05).③在凋落叶分解过程中,C、N、P含量及其化学计量比随时间存在明显差异(p0.01),并且地上组TC、TN、C/N和C/P明显不同于地下组(p0.05).④在分解过程中,4种水解酶随时间存在明显差异(p0.01).⑤凋落叶酸性磷酸酶活性与土壤温度、电导率和凋落叶TP含量存在显著相关关系(p0.01).这些结果说明,秋茄凋落物产量及元素含量随季节变化存在明显差异;沉积作用对凋落叶分解过程中元素含量有显著影响,水解酶活性主要受凋落叶元素含量和土壤环境因子的控制.

Litter production and decomposition dynamics of Kandelia obovata from a mangrove swamp in Min River estuary

Using litter collection box and litter bag techniques, the production and decomposition dynamics of Kandelia obovata from an estuarine mangrove swamp in Min River estuary were measured in 2017. The results showed that the annual litter production of K. obovata was 618.79 g·m^-2·a^-1, of which the leaf was the most abundant, accounting for an average of 61.2% of all production, followed by fruit, branch and flower, with contributions of 23.7%, 10.5%, and 4.6%, respectively. The total nitrogen (TN) content of litter was highest in August 2017, while the total phosphorus (TP) content was significantly higher in January-March than in other months. The litter carbon/nitrogen (C/N) ratios were lowest in August, while the carbon/phosphorus (C/P) ratios and nitrogen/phosphorus (N/P) ratios were significantly higher in September than in other months. During the decomposition of leaf litter, the C, N, P contents and its stoichiometric ratios showed significant differences with time. The TC, TN, C/N and C/P of the aboveground groups were significantly different from those of the underground groups. The acid phosphatase activity was significantly correlated with soil temperature, soil electric conductivity and litter TP content. These results indicated that the production and elemental content of K. obovata litter were significantly different with seasons; sedimentation significantly affected the element content during leaf litter decomposition, and soil environment factors and litter element content were important factors controlling hydrolase activity.