|Otieno, DO; Mirzaei, H; Hussain, MZ; Li, Y; Schmidt, MWT; Wartinger, M; Jung, EY; Ribeiro, N; Pereira, JS; Tenhunen, J: Herbaceous layer development during spring does not deplete soil nitrogen in the Portuguese montado, Journal of Arid Environments, 75(3), 231-238 (2011), doi:10.1016/j.jaridenv.2010.10.011|
|Key words: Biomass development of the herbaceous vegetation, Mediterranean ecosystems, Portuguese montado, PasturePlant 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 soil N within the top 20 cm soil profile ranged between 0.2 ± 0.1% in February and 0.41 ± 0.2% in May, 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−1soil 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.