Seasonal variation of inorganic nitrogen and net mineralization in a salt marsh ecosystem |
| |
| Authors: | Cartaxana P Caçador I Vale C Falcão M Catarino F |
| |
| Institution: | (1) Instituto de Oceanografia, Faculdade de Ciências da, Universidade de Lisboa, Campo Grande, 1700 Lisboa, Portugal;(2) Instituto de Investigação das Pescas e do Mar (IPIMAR), Av.Brasília, 1400 Lisboa, Portugal |
| |
| Abstract: | Inorganic nitrogen pools and net mineralization were estimated in three sites of a Tagus estuary salt marsh in Portugal throughout 1 year. Ammonium (NH4
+) was the major form of inorganic nitrogen found in the salt marsh soil. Extractable NH4
+ concentrations showed a marked seasonal pattern with a concentration peak during the hotter months of July/August. The great majority (>99%) of the total nitrogen in the soil was found in sedimented organic matter, not readily available for plant uptake. Net nitrogen mineralization, determined using a field incubation method, showed a peak during the months of June/July which resulted in an increase on nitrogen availability. With the exception of the lower salt marsh, estimated rates of in situ net nitrogen mineralization in the soil during summer were well related to the increase in plant above ground biomass and plant nitrogen pools, indicating that the process is an important source of available nitrogen for plant uptake and growth. Annual net nitrogen mineralization ranged between 2.4 and 4.5 gNm–2yr– 1 being significantly higher for the lower salt marsh site. Rates of net nitrogen mineralization were relatively low during most of the year with a particularly active period from June to August, possibly due to an effect of temperature on soil microbial activity. |
| |
| Keywords: | ammonium availability cycling nitrate Tagus estuary |
| 本文献已被 SpringerLink 等数据库收录！ |
|
