Herbaceous layer development during spring does not deplete soil nitrogen in the Portuguese montado

• Main Author: Otieno, D.O.
• Publication Date: 2010
• Other Authors: Mirzaei, H., Hussain, M.Z., Li, Y.L., Schmidt, M.W.T., Wartinger, M., Jung, E., Ribeiro, N., Pereira, J.S., Tenhunen, J.
• Format: Article
• Language: por
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://hdl.handle.net/10174/10188
• topic: Biomass development of the herbaceous vegetation; Mediterranean ecosystems; Portuguese montado; Pasture; Plant and soil nitrogen pools; Root distribution and nutrient uptake; Soil moisture

Nitrogen (N) content in the soil and in the herbaceous biomass were monitored during spring of 2004-2006 to determine how the herbaceous layer development influences soil N availability in the montado ecosystem of southern Portugal. Highest (246.6 ± 52.7 g m-2) and lowest (123.2 ± 89.5 g m-2) peak biomass occurred in 2006 and 2005 respectively. Total soilNwithin the top 20 cmsoil profile ranged between 0.2 0.1% in February and 0.41 0.2% inMay,while available soil N was lowest (5 ± 2 μg g-1soil) in February but increased three-to-five fold in March and was >17.5 μg g-1 soil at senescence in May. Significant (p < 0.001) increase in total N in the aboveground pool occurred between February and May. There was however, no decay in soil N content. Instead, the herbaceous vegetation enhanced soil N input and N retention in the ecosystem. Most of the herbaceous plants were annuals with large reserves of organic N at senescence, which returned to the soil as detritus. The herbaceous vegetation is a critical component of the montado that contributes to N recharge and cycling within the ecosystem.