Abstract: In this paper, the biomass, caloric value, ash content, and carbon content of natural Pinus tabulaeformis and Quercus aliena var. acuteserrata communities along an altitudinal gradient on the southfacing slope of middle Qinling Mountains, China were determined, aimed to explore the distribution patterns of the two communities’ biomass and energy at different altitudes. With the increase of altitude, the standing biomass and energy of the two communities decreased after an initial increase. The total biomass of P. tabulaeformis and of Q. aliena var. acuteserrata was the highest at altitude 1500-1600 m and 1400-1500 m, being 263.94
 t·hm^-2 and 278.71 t·hm^-2, respectively, while the total energy was all the highest at altitude 1400-1500 m, being 5715.38 GJ·hm^-2 and 5756.13 GJ·hm^-2, respectively. At the same altitudes, the caloric value and carbon content of P. tabulaeformis were higher than those of Q. aliena var. acuteserrata, but the ash content was in opposite. The caloric value and average caloric value of different organs of P. tabulaeformis increased with increasing altitude, while those of the bark of Q. aliena var. acuteserrata were in adverse. The average carbon content of P. tabulaeformis and of Q. aliena var. acuteserrata increased with increasing altitude, while the ash content had no regularity. The caloric value, ash content, and carbon content of P. tabulaeformis at different altitudes were 2039-21.47 kJ·g^-1, 2.81%-3.54%, and 46.20%-50.50%, while those of Q. aliena var. acuteserrata were 19.69-20.18 kJ·g^-1, 6.15%-7.77%, and 42.06%-44.15%, respectively. For P. tabulaeformis, significant differences were found in the caloric value and carbon content at different altitudes, but little difference was observed in the ash content. For Q. aliena var. acuteserrata, significant differences were found in the ash content and carbon content at different altitudes, but little difference was observed in the caloric value. It was considered that the microhabitat at medium altitude was more appropriate for the growth of P. tabulaeformis and Q. aliena var. acuteserrata.

Key words: pheromones, biological control., Apis mellifera, Varroa destructor