Geographic Variation Trend For Tracheid Morphological And Microfibril Angle In Plantation Forest Of Loblolly Pine

Loblolly pine was one of the most important short-rotation industrial forest species which was introduced successful in China. Its growth characteristics and wood properties had great relationships with cultivation environments. The variation in them had great differences as the different climate in the introduction and cultivation areas of Loblolly pine. The research on geographic variation trend for wood properties of plantation and pulpwood of Loblolly pine had important significances in determining the best planted areas and cultivating high-quality timber. Wood properties for plantation wood of Loblolly pine planted in 11 major growing areas which were determined by longitude and latitude were studied in this paper. The research would provide the scientific basis for directiving cultivation and rational using of the timber resources.The annual ring width of Loblolly pine introduced the maximum in the 3-4a at radial direction, then decreased gradually, and generally stabilized after 9a. The latewood percent increased in the early period, leveled off after 9a. Regression equation can be determined according to the relationship between annual ring width, latewood percent and the age. It can be used to predict the.values of annual ring width and latewood percent by the age of the Loblolly pine. There were great differences on the latewood percent among locations and tree-ages from two-factor analysis of variance on 1-9a of Loblolly pine planted in 11 areas. Multiple comparisons showed that the diversity of annual ring width was more significant with the increasing of the tree-age.Tracheid length, tracheid width, tracheid double wall thickness, tracheid length-width radio and tracheid wall thickness-diameter ratio increased obviously from pith to park. The above features in 1-5a increased rapidly than that in other ages. Loblolly pine planted in China belonged to finest grade pulpwood from the morphological numerical value. Multiple comparisons showed some geographic variations. Variation coefficient in annual rings of tracheid morphological features demonstrated that the region was more obvious, and the growth is instability in the early periods. While the coefficient of variation within locations was lower than that among locations after 7a.From the latewood percent of Loblolly pine planted in Henan, Hubei, Hunan, Jiangxi and Guangdong where the latitude is quite different but the longitude is similar, it can be found that a significant tendency decreasing with the function of latitude’s lower. Tracheid length in Jiangxi and Guangdong were larger than that in the other areas. Differences on tracheid width and tracheid diameter were not obvious. The radial variations in tracheid double wall thickness and tracheid wall thickness-diameter ratio’s differences in 1-4a were not significant, but the trends were obviously different with the latitude’s lower, which were Guangdong〉Jiangxi〉Hunan〉Hubei〉Henan. The annual ring width and the latewood percent of Loblolly pine in Guangxi were slighter lager than that in Chongqing. Tracheid length and tracheid double wall thickness in Loblolly pine-planted in Guangxi were significant lager than that in Chongqing. The variation trends of Loblolly pine planted in the eastern coastal regions were the same as the above mainlines. The annual ring width and the latewood percent of Loblolly pine in Shandong were significant less than that in Zhejiang and Fujian.The difference on annual ring width and the latewood percent of Loblolly pine in Chongqing, Hubei, Anhui and Zhejiang where the latitude is similar but the longitude is different was not significant. The variation trend along longitude was not obvious. Tracheid length of Loblolly pine in Chongqing and Zhejiang were obviously longer than those planted in Hubei and Anhui. The radial variation on tracheid width, tracheid diameter and tracheid double wall thickness were relatively stable along longitude.The radial variation of MFA in Loblolly pine was decreased at the early growing years, and then generally stabilized. There was significant negative correlation between MFA and tracheid length. There were great differences at the level 0.01 of MFA among locations and tree-ages from two-factor analysis of variance on Loblolly pine planted in 8 areas. The correlations between MFA and meteorological factors were stable, but could not reach a significant level. Geographical characters variation trend along the latitude and longitude was showed from MFA. The correlation between MFA and latitude was positive, which was different from that between tracheid length and latitude.There were some correlations between tracheid morphological features, annual ring width, latewood percent and meteorological factors for wood properties of Loblolly pine. The correlation was not remarkable in 1-3a, and then it would become higher after 4a. There were significant positive correlations between latitude and tracheid length, tracheid double wall thickness, latewood percent. And the correlation between latitude and tracheid diameter-width radio was negative. The correlations between mean annual temperature and the above features were opposite. Tracheid length and latewood percent could be determined by minimum temperature and frost-free season. Longitude, maximum temperature and annual precipitation had low correlation coefficients with tracheid morphological features, annual ring width and latewood percent in Loblolly pine. Some correlations between tracheid morphological features and wood properties were significant in Loblolly pine planted in Henan, Hubei, Hunan, Jiangxi and Guangdong where the latitude is quite different but the longitude is similar. There were significant negative correlations between latitude and tracheid double wall thickness. The correlation between latitude and tracheid diameter-width radio was positive. There were significant positive correlations between average temperature and tracheid double wall thickness, latewood percent, and the correlation between average temperature and tracheid diameter-width radio was opposite. Maximum temperature, minimum temperature, annual precipitation and frost- free season had low correlation coefficients with tracheid morphological features, annual ring width and latewood percent. The correlations in Loblolly pine planted in the eastern coastal regions were similar with the above mainlines. The correlation between mean annual temperature and tracheid length was significant positive. The correlation between annual precipitation and tracheid double wall thickness, and the correlation between frostless periods and tracheid length-width radio were significant positive.From the correlation of Loblolly pine among Chongqing, Hubei, Anhui and Zhejiang where the latitude is similar but the longitude is different, there were non-significant correlations between longitude and morphological features, which could show that growth characteristics and wood properties of Loblolly pine were not obvious influence on longitude.