Effects of condensed tannin of Onobrychis viciaefolia hay on the rumen metabolism and in situ degradation of diets by sheep.

Trees from plots (22) of 2 clones of 4 and 6-8 year old Casuarina and from two species of 8 year old Acacia stands,were measured for growth and wind-resistance traits such as wood density and pilodyn penetration in a site at the Nansan coastal protection forest in Zhanjiang.Diameter at breast height (DBH),pilodyn data,wood base density (WBD) and bark thickness (BT) were made at a height of 1.3 m while WBD was measured on whole wood cores from 1.3 m height taken by increment borer.In general,growth traits such as DBH,tree height,bark thickness,crown width,and WBD increased with forest age but there were significant differences in stand growth between species.There were also significant differences in all traits between forest ages.All traits except for branch angle and DBH were significantly correlated.The traits were divided into three categories and examined by principal-component factor analysis.The results of hierarchical cluster analysis in which Euclidean distance was taken as a similarity measure and the average linkage cluster method was used as a clustering algorithm showed that there were significant differences in traits between plots:Two plots of A.mangiums and A.confuse stands were classified in a category,and No.5 and No.6 Casuarina stands were classified as the same cluster and were significantly different from the others because their plots were located in front of the protection forest belt.The stands were hit by Typhoon Kammuri and the strong Typhoon Hagupit in 2008.They were located 120-130 km from the eyes of the two storms.Almost all Casuarina stands had low grade wind damage (e.g.branch-breakage) only,but there was considerable wind damage to the Acacia stands where damage to A.mangiums and A.confuse plots was level six and five respectively.A regression model of stand wind damage with growth and wind-resistance traits was developed.The statistic R2 was 0.861 and showed the linear regression was a good fit to the data.For categorical traits,acoustic velocity (AV),WBD and pilodyn penetration value (PPV) were major while branch angle,tree height,and stem strength were minor in determining the meaning of wind damage grade.An increase in tree height,crown width,PPV,and GSV resulted in an increase in predicted wind damage grade.In terms of the regression,the plot with the worst fit was Acacia mangium,the second was Acacia confuse,and the best was Casuarina clone 701,whereas stands of two Casuarina clones were not significantly different.