Variations in C, N and P stoichiometry of leaf-litter-soil associated
with Mongolian pine by stand origin, Northern China
Abstract
Ecological stoichiometry is an important approach to understand the
nutrient cycling and balance through the leaf-litter-soil system of
Mongolian pine among different stand origins in desert regions. To
reveal the variations in Mongolian pine carbon (C), nitrogen (N), and
phosphorus (P) stoichiometry and stoichiometric homeostasis among
different stand origins, we measured C, N, and P concentrations of
leaves, litter, and soil, and analyzed the nutrient resorption
efficiencies of leaves in differently aged plantations and natural
forests from semi-arid and dry sub-humid regions. The results showed
that (a) the stand origin had a significant effect on the C-N-P
stoichiometry, and also significantly affected leaf N and P reabsorption
efficiencies. Leaf N/P ratios indicated that Mongolian pine was
co-limited by N and P in the NF, HB and HQ, and was mainly limited by P
in MU. (2) With increasing stand age, C concentrations in the
leaf-litter-soil system initially increased and then decreased, the N
and P concentrations and reabsorption efficiencies in the
leaf-litter-soil system were gradually increased. Overall, stand age had
a significant effect on N concentrations, C/N and C/P ratios in the
leaf-litter-soil system. (3) The C and N elements between the
leaf-litter-soil system had a strong coupling relationship, and the P
element between litter-soil had a strong coupling relationship. In
addition, plantations exhibited greater N/P homeostasis than natural
forests, and N/P exhibited greater homeostasis than N and P alone, which
may be a nutrient utilization strategy for forests to alleviate N or P
limitation. (4) Environmental factors have a significant influence on
C-N-P stoichiometry in the leaf-litter-soil system, the most important
soil properties and meteorological factors being soil water content and
precipitation, respectively. These results will be essential to provide
guidance for plantation restoration and management in desert regions.