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对川西高山树线红杉新鲜凋落物中有机组分于11月进行自然条件(对照)、加氮(2g N·m~(-2))、增温(顶开式培养室)、加氮+增温4个处理的原位培养,并监测凋落物中有机组分的分解动态.结果表明:在试验开始后4个月内,增温、加氮以及加氮+增温处理比对照显著促进了红杉凋落物中水溶性糖、水溶性酚和多酚的分解,但随着培养时间的延长,累积分解量的差异逐渐缩小.与对照相比,增温、加氮和增温+加氮处理均抑制红杉凋落物中CH_2Cl_2提取组分、酸溶碳水化合物、酸溶木质素和非酸溶木质素分解,其中增温处理抑制作用最强,加氮处理抑制效果最弱,增温+加氮处理介于二者之间;增温处理对非酸溶木质素和CH_2Cl_2提取组分的半分解周期延长1倍以上,热水溶组分的半分解周期延长50%以上.在原位培养条件下,红杉新鲜凋落物中水溶性糖、水溶性酚、多酚、酸溶碳水化合物、酸溶木质素是较容易分解的有机组分,半分解周期分别为182、159、127、154和190 d;热水溶组分、CH_2Cl_2提取组分和非酸溶木质素是较难分解的有机组分,半分解周期分别是209、302和318 d;尽管低温季节(11月至次年3月)极其寒冷,气温均低于0℃,常被认为是微生物活性最弱、有机物分解最慢的时期,但结果显示低温季节期间红杉凋落物各有机组分却分解最快.因此,氮沉降和升温将迟滞该区域高寒红杉林凋落物的分解.这将有利于高寒森林生态系统的土壤碳固持.
The organic components of fresh litter of sequoia highland in western Sichuan were subjected to natural conditions (control), nitrogen (2g N · m -2), warming (open top chamber), nitrogen + Warming four treatments in situ and monitoring the decomposition dynamics of organic components in litter.The results showed that in the four months after the start of the experiment, warming, adding nitrogen and adding nitrogen + Promoted the decomposition of water-soluble sugars, water-soluble phenols and polyphenols in sequoia litter, but gradually decreased with the increase of incubation time.Compared with the control, the warming, nitrogen and warming + Adding nitrogen could inhibit the decomposition of CH_2Cl_2, acid-soluble carbohydrates, acid-soluble lignin and non-acid-soluble lignin in the litter of sequoia, with the strongest inhibition of warming and the weakest of adding nitrogen, Temperature + plus nitrogen treatment in between the two; warming treatment of non-acid-soluble lignin and CH_2Cl_2 extraction components of the semi-decomposition cycle more than doubled, hot water-soluble components of the semi-decomposition cycle longer than 50% Under the condition of bit culture, water-soluble sugars, water-soluble phenols, polyphenols, acid-soluble carbohydrates, Acid-soluble lignin is a more easily decomposed organic component with semi-decomposition cycles of 182, 159, 127, 154 and 190 days, respectively. Hot-water soluble components, CH 2 Cl 2 -extracted components and non-acid soluble lignin are more difficult to decompose organic Components and semi-decomposition cycles were 209, 302 and 318 days respectively; although the cold season (November to March) was extremely cold with temperatures below 0 ° C, it was often considered to be the weakest in microbial activity with the slowest decomposition of organic matter , But the results showed that the decomposition of organic components of Sequoia litters was the fastest during the low temperature season.So the nitrogen deposition and temperature rise would delay the decomposition of the litter in the alpine redwoods in this region.This would be beneficial to the soil of the alpine forest ecosystem Carbon hold.