How do trees affect spatio-temporal heterogeneity of nutrient cycling in mediterranean annual grasslands? uri icon

abstract

  • Contrary to what was expected, plant nutrient concentrations did not directly reflect those found in the soil, with the exception of K. The studied grassland responded to increased nutrient availability by enhancing growth and changing botanical composition rather than by increasing plant nutrient concentrations. Hence, the total amount of accumulated nutrients in the ecosystem was larger below the tree than outside it, although this is mainly a consequence of plant growth enhancement. The levels of Ca, Mg, and Na in plants decreased during the driest year, and the N content was mostly determined by the composition of the grass.
  • In this study we analyzed heterogeneity in nutrient cycling induced by trees in Mediterranean annual grasslands, comparing years of higher and lower than average precipitation and analyzing the effects of two different solar radiation scenarios.
  • Organic matter and consequently upper soil N, K, Ca and Mg were significantly greater in those locations receiving the highest levels of solar radiation, and as expected from many other studies in the literature, there was an increase in all macronutrients ( except P) as well as pH below the canopy.
  • Temporal nutrient variability, particularly within-years, explained most of the variability in plant nutrient concentration, while spatial variability induced by trees was determined to be of secondary importance. These results are significant for ecosystem nutrient modelling.

publication date

  • 2010
  • 2010