Investigation and Analysis of Parasitic Characteristics of <i>Taxillus thibetensis</i> in Kunming Haikou Forest Farm

Abstract

Mistletoes (Loranthaceae) is well known as a common hemi-parasitic shrub and its excessive reproduction can limit the function of natural forest and plantation on ecology, economy and society. By investigation, mistletoes were found in some area of Kunming Haikou Forest Farm, and the main type is Taxillus thibetensis . To monitor the spread of parasite and understand the choice preference, our study had focused on the enrichment areas of T .  thibetensis in Kunming Haikou Forest Farm and conducted sample surveys from the center and four adjoining areas. The host selection of T. thibetensis  was investigated and the regression relation between parasitic intensity and host growth characteristics was constructed. The results showed that the quadrat Two (M2; enrichment center) characterized by minimum canopy density (30%) and maximum slope gradient had a serious damage, while a few influence was found in others four quadrats (M1, M3, M4, and M5; adjoining areas), suggesting an initial stage of parasite spread. T. thibetensis  showed a strong host selection and Quercus aliena was main host plants. There was no clear correlation between the spread of T. thibetensis  and proportion of  Q. aliena in community. The stepwise regression reveals the linear relationship between parasitic intensity and host characteristics. Crown width and diameter of Q. aliena  were introduced into regression model under corrected R 2  fitting of 0.526, and the equation was y=-0.467+0.152x 1 +0.110x 2 . The parasitic position of T. thibetensis  in M2 and M1 focused on the 40%~80% of host plants height, while the parasites were scattered over the trees in M3, M4 and M5. This work lays a scientific foundation for ecological control of T .  thibetensis .