Plus Tree Resource Survey and Genebank Construction for Cunninghamia lanceolata

Based on a largescale investigation into Cunninghamia lanceolata stands in Lechang area of Guangdong Province, a total of 104 plus trees of C. lanceolata were screened out, and the trait indexes including height, DBH, form index, standing volume, wood quality and growth properties of the plus trees were measured and analyzed. The results showed that the average values of tree height, DBH, and standing volume of the plus tree population were all significantly (P<0.01) higher than those of the sample plot population, whose phenotype level was above 77.0. Further analyses revealed that the real gain of tree height, DBH, and standing volume indexes of the plus trees could achieve to 0.4%-97.1%, 32.3%-131.8%, and 82.6%-712.5% respectively. The heightDBH ratio and the crownDBH diameter ratio ranged from 38.9 to 76.5, and from 8.7 to 21.9 individually. The basic wood density(DEN), redheartwood ratio(RHR), shrinkage (SH) and hygroscopicity (HY) of the plus trees changed in amplitudes of 0.2511-0.3931g/cm3, 29.2%-72.3%, 0.8%-32.4%, and 189.0%-332.9% respectively. Notably, the trait of SH varied most significantly among the plus trees with phenotypic variation coefficient (CV) of 100%, while the DEN index varied much less with a CV of 11%. By using the meantrees as controls, a considerable number of plus trees with qualified wood were herein identified. Currently, the germplasm resources of C. lanceolata plus trees were well conserved by both in situ and ex situ methods. The compacted ex situ conservation ratio appeared to be 981%.