Abstract: Spruce-fir forest was one main type of subalpine dark coniferous forest in Southeast Tibet.After a comprehensive investigation on spruce-fir forest distributed in Gongbu Nature Reserve of Southeast Tibet by transects and quadrats,spatial distribution and spatial associations of Picealikiangensis var.linzhiensis and Abiesgeorgei var.smithiipopulation were analyzed and explored by Ripley function.The results showed that the spatial distribution pattern of two populations were discrepant with different altitude and scale.The pattern of A.georgei var.smithii population in four plots was as follows:aggregated distribution (P1)→random distribution (P2)→aggregated distribution (P3)→random distribution (P4),and there was aggregated distribution in small scale.The pattern of P.likiangensis var.linzhiensispopulation in four plots was aggregated distribution (P1)→random distribution (P2)→random distribution (P3)→aggregated distribution (P4),and the aggregated distribution appeared in low altitude and small scale,or in high altitude and large scale.The interspecific relationship of two populations in four plots was in order of no significant correlation(P1)→significant negative correlation in small scale(P2)→significant positive correlation in large scale(P3)→significant negative correlation in large scale(P4).The research results provided a theoretical basis for management and sustainable utilization of spruce-fir forest,and enriched the assessment content of the national ecological security barrier in Tibet plateau.

Key words: subalpine dark coniferous forest, spatial distribution, interspecific relationship, Southeast Tibet