Phosphorus fraction characteristics and influencing factors of soil aggregates in pure and mixed forests.

Phosphorus components in the soil aggregates of different particle sizes is critical for improving phosphorus availability in north subtropical regions. We investigated two representative stand types, pure stands and the mixed stands of and in Lishui District, Nanjing. We measured soil aggregates from two soil layers (0-20 cm and 20-40 cm) to determine the stability of soil aggregates, labile phosphorus fraction content and the acid phosphatase activity of each particle size, as well as litter biomass and fine root biomass, to analyze the differences of active phosphorus fractions of soil aggregates between different stand types.

[Effects of thinning on fine-root morphology, biomass and N concentration of different branch orders of Chinese fir].

Taking a 25-year old Chinese fir (Cunninghamia lanceolata) plantation as the object, this paper studied the effects of thinning on the biomass, morphological traits, and nitrogen concentration of the first five orders roots. With the increase of root order (from the first to the fifth order), there was a significant increase in the fine-root biomass, diameter, and tissue density, and a significantly decrease in the specific root length (SRL), root length density (RLD), and root number (RN). Thinning increased the biomass, RLD, and RN of the first and second orders roots as well as the tissue density of the first, third, fourth, and fifth orders roots significantly, but had no effects on the SRL and nitrogen concentration of each order root.