© 2005 Heron Publishing—Victoria, Canada
Contrasting net primary productivity and carbon distribution between neighboring stands of Quercus robur and Pinus sylvestris
J. Curiel Yuste (1, 2), B. Konôpka (1), I. A. Janssens (1), K. Coenen (1), C. W. Xiao (1) and R. Ceulemans (1)
1. University of Antwerp, Department of Biology, Research Group of Plant and Vegetation Ecology, Universiteitsplein 1, B-2610
Wilrijk, Belgium / 2. Corresponding author (jkuriel@nature.berkeley.edu) / Received March 8, 2004; accepted November 9, 2004; published online April 1, 2005
Summary
Standing biomass, net primary production (NPP) and soil carbon (C) pools were studied in a 67-year-old pedunculate oak (Quercus robur L.) stand and a neighboring 74-year- old Scots pine (Pinus sylvestris L.) stand in the Belgian Campine region. Despite a 14% lower tree density and a lower tree height in the oak stand, standing
biomass was slightly higher than in the pine stand (177 and 169 Mg ha–1 in oaks and pines, respectively), indicating that individual oak trees contained more biomass than pine trees of similar
diameter. Moreover, NPP in the oak stand was more than double that in the pine stand (17.7 and 8.1 Mg ha–1 year–1, respectively). Several observations indicated that soil organic matter accumulated at higher rates under pines than under
oaks. We therefore hypothesized that the pines were exhibiting an age-related decline in productivity due to nutrient limitation.
The poor decomposability of pine litter resulted in the observed accumulation of organic matter. The subsequent immobilization
of nutrients in the organic matter, combined with the already nutrient-poor soil conditions, resulted in a decrease in total
NPP over time, as well as in a substantial shift in the allocation of NPP toward fine roots. In the oak stand, litter is less
recalcitrant to decay and soil acidity is less severe; hence, organic matter does not accumulate and nutrients are recycled.
This probably explains why NPP was much higher in the oaks than in the pines and why only a small proportion of NPP was allocated
to oak fine roots.
Keywords:
allometric relationships, biomass distribution, NPP, nutrient stress, pedunculate oak, Scots pine, soil carbon.
