An alternative explanation for the post-disturbance NO3- flush in some forest ecosystems
An alternative explanation for the post-disturbance NO3- flush in some forest ecosystems
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DOI：
10.1046/j.1461-0248.2001.00243.x
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发表时间：
2001-09-01
期刊：
影响因子：
8.8
通讯作者：
Bradley, RL
中科院分区：
文献类型：
--
作者：
Bradley, RL
森林干扰后土壤NO3-的出现通常归因于自养硝化菌对NH 4+的有效性增加，或有效C减少导致微生物对NO3-的同化作用降低。或者，已经提出，增加NH 4+池干扰后，可以通过减少微生物同化NO3-增加净硝化作用。从防护林收获地块，表现出低有效碳和低NH 4+池，并在以前的实验表明异养硝化的患病率的森林地面材料收集。子样品进行了修订与葡萄糖-C或NH 4+的增量率，和总NO3-转化率进行了测量同位素稀释。葡萄糖-C添加对总NO3-生产和消费率之间的净差异影响不大。另一方面，NH 4+的添加导致总NO3-消耗过程急剧减少，而总NO3-生产过程保持不变。结果表明，NH 4+可以通过抑制NO3-同化和吸收系统对净硝化速率产生直接的积极影响。
The appearance of soil NO3- after forest disturbance is commonly ascribed to a higher availability of NH4+ to autotrophic nitrifiers, or to a reduction in available-C resulting in lower microbial assimilation of NO3-. Alternativelv, it has been proposed that increasing NH4+ pools following disturbance could increase net nitrification by reducing microbial assimilation of NO3-. Forest floor material was collected from shelterwood harvest plots which displayed both low available-C and low NH4+ pools, and where previous experiments had suggested the prevalence of heterotrophic nitrification. Subsamples were amended with incremental rates of glucose-C or NH4+, and gross NO3- transformation rates were measured by isotope dilution. Glucose-C additions had little effect on the net difference between gross NO3- production and consumption rates. On the other hand, NH4+ additions caused gross NO3- consumption processes to decrease sharply, while gross NO3- production processes remained constant. The results suggest that NH4+ can have an immediate positive effect on net nitrification rates by suppressing NO3- assimilation and uptake systems.