Abstract: [objectice] Dalbergia odorifera is an endemic tree species in Hainan, and listed as the second class rare and endangered species by the state. With the increase of D. odorifera plantation scale in Hainan province, the disease problems of D. odorifera has become increasingly prominent, of which mainly occur on foliage. Colletotrichum gloeosporioides and Phyllachora dalbergiicola are the most harmful pathogens. In order to investigate the occurrence mechanism of the main foliage diseases in D. odorifera and provide a theoretical basis, this research studies the correlation between community structure characteristics and D. odorifera foliage diseases. [Method] Based on D. odorifera distribution and the diseases occurrence in Hainan province, 41 sample plots were set up in Hainan province. Both field survey and plot survey was used to investigate diseases. Eight stand factors were selected as investigation index. They were height, ground diameter, stand age, stand density, canopy cover, herb cover, herb height, and crown. Stepwise regression was used to select dominant factors affecting the foliage diseases occurrence on D. odorifera plantations. One-way ANOVA, two-factor analysis of variance, correlation analysis, multiple comparisons and other methods were used to further analyze the relationships between significant factors and foliage diseases.[Result] Results from regression analysis showed that there were five dominant factors affecting the diseases. They were stand density, stand age, canopy cover, stand herb cover and stand crown. Stand density was the key factor, affecting the disease incidence (DI) and disease severity index (DIS) significantly (P < 0.01). DI and DIS were positively correlated with stand density (R=0.852,P=0.000; R=0.851, P=0.000). The stand age(1-12 a)significantly affected DI and DIS, and DI and DIS were negatively correlated with stand age (R=-0.797, P <0.01; R=-0.653, P <0.01). Stand canopy cover affected DI and DIS significantly, and DI and DIS was positively correlated with different stand canopy cover (R=0.644, P=0.024; R=0.646, P=0.023). DI and DIS varied in different stand canopy cover. The higher the stand canopy cover was, the much more severe the disease was found. The effect of stand herb cover on DI and DIS showed the same trend with stand canopy cover (R=0.560, P=0.010;R=0.533, P=0.006). DI and DIS varied in Ⅰ, Ⅱ, and Ⅲ level stand herb cover. The higher the stand herb cover was, the much more severe the disease was found. Stand crown affected DI and DIS significantly, DI and DIS was negatively correlated with different stand crown (R=-0.544, P=0.027; R=-0.621, P=0.012). With the increase of stand crown, DI and DIS of stand decreased inversely. These results indicated that stand density was the most important factor to D. odorifera foliage diseases (P < 0.01). [Conclusion] Thus, it is suggested that regulation of stand density, and rational close planting in afforestation are the dominant measures, and simultaneously other four stand factors should also be taken into consideration to reduce the diseases occurrence of D. odorifera.

Key words: Dalbergia odorifera, plantation, community structure, foliage diseases