Abstract: Nutrient resorption, one of the important mechanisms for nutrient conservation in plant species, plays an important role in litter decomposition and nutrient cycling. To clarify the nutrient resorption between Larix spp. in the plantation forest and four native broadleaved tree species (i.e., Quercus mongolica, Acer mono, Juglans mandshurica and Fraxinus rhynchophulla) in the secondary forests, we measured N, P and K concentrations in mature and senescent leaves of these five tree species in a montane region of eastern Liaoning Province, China. The results showed that the N, P and K concentrations of senescent leaves were significantly lower than those of mature leaves, except for the K concentration of Larix spp. (P<0.05). The N resorption efficiency of J. mandshurica was significantly different from that of the other three broadleaved tree species (P<0.05). The P resorption efficiency of F. rhynchophulla was significantly different from that of Q. mongolica and A. mono (P<0.05). Furthermore, the K resorption efficiency of A. mono was significantly different from that of the other three broadleaved tree species (P<0.05). N, P and K resorption efficiencies of Larix spp. were generally lower than those of the broadleaved tree species, especially its P resorption efficiency was significantly lower than that of F. rhynchophulla (P<0.05) and its K resorption efficiency was significantly lower than that of J. mandshurica and F. rhynchophulla (P<0.05). All of these indicated that the larch made a positive feedback on soil nutrient availability via reducing the nutrient resorption efficiency and improving the litter nutrient input.

Key words: target enzyme, pesticide, multi-pesticide resistance, ecological equilibrium