关键词: N₂O, 稳定同位素, SP值, 灌溉, 反硝化作用, 硝化作用

Abstract: There distributes typical elfin forest community in Shikengkong of Nanling Mountains, but little is known about the interspecific relationships between the dominant tree species in the community. By using 2×2 contingency table, variance analysis, association index, χ²text, Pearson’s correlation coefficient, and Spearman’s rank correlation test, this paper quantitatively studied the interspecific associations of 120 species pairs of 16 dominant tree populations with higher importance value. The results of variance analysis showed that there existed significant positive correlations among the 16 dominant species, suggesting that this community was at a more stable climax stage. The χ² test illustrated that there were 66 species pairs in positive association, and 54 species pairs were in negative association, with the ratio of positive to negative association being 1.22. The Pearson’s correlation coefficient test displayed that 65 species pairs were in positive association, and 55 species pairs were in negative association, with the positive/negative association ratio being 1.18. The Spearman’s rank correlation coefficient test reflected that 64 species pairs were in positive association, while 56 species pairs were in negative, with the positive/negative association ratio being 1.14. The association index showed that most species pairs had lower degree of association. Among the 120 species pairs, most pairs did not show significant association, which could be due to their ecological characteristics and the seral stage of the community. This forest community was at the late-successional stage and quite stable.

Key words: stable isotope, site preference value, nitrification, N₂O, irrigation., denitrification