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Research To Variation Of Growth, Wood Characters And The Provenance Test Of Schima Superba

Posted on:2011-10-22Degree:MasterType:Thesis
Country:ChinaCandidate:X H WangFull Text:PDF
GTID:2143360308982265Subject:Forest cultivation
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In this article, six natural stands of S. superba with latitude and elevation gradient in Zhejiang and Fujian provinces and the fully distributed provenance test of S. superba at age seven including 33 seed sources conducted at Jian'ou of Fujian were used to study individual phenotypic variation, provenance differences and geographic hereditary variation pattern for individual type, stem form and wood density, and carried on the provenance regions regionalization and the fast-growing high quality provenance choice based on the cultivation objective. Meanwhile, to propose the necessary cultural technique on how to promote early time fast-growing, high quality and bumper crop of craft timber stands, several S. superba pure stands and S. superba - Chinese fir mixed stands afforested during 1968-1997 were selected to study the effect of site condition and mix planting with Chinese fir on growth, form and wood basic density of S. superba plantation in Jian'ou, Fujian province. The main results are as follows:1. Among natural stands of S.superba, types of bark traits and wood color were various, there were significant differences in stem form, bark type and wood basic density, but not in wood texture distortion degree among different stands. In contrast, the largest within-stand variation in wood texture distortion degree and the lesser within-stand variation in stem fullness, stem straightness and wood basic density were observed. Radial analysis in wood property showed that wood basic density decreased from pith to bark gradually. The ring width was increased at first and followed by a reduction, with a stable growth phase during 15th to 25th rings. Results also demonstrated that natural stands from higher latitudes exhibited higher stem fullness and straightness, thinner bark and lighter wood color relatively, whereas no clear regularity were observed for other characters. The effect of elevation was significant in comparison with latitude, as increased trunk fullness, thinner and smoother bark, as well as decreased trunk straightness, ring width and wood basic density were observed in natural stands from higher elevation.The individual correlation analysis based on two natural stands from different elevation in the central production region showed that the correlation among traits were quite different and depending on different elevation of stands. In high-elevation stands, bark traits could be used as morphological indicators for wood properties and diameter growth. Individuals with higher stem fullness usually exhibited less wood basic density, as well as bark with lighter color and smooth surface. Meantime, individuals with higher stem straightness and dark bark usually exhibited faster grew speed in diameter. For stands from low-elevation, bark thickness was a good indication on wood basic density and other traits, as decreased wood texture distortion degree and increased wood basic density were observed in individuals with higher stem straightness, lighter bark color and large DBH increment.2. The results revealed a significant effect of slope position and slope direction on the growth and stem form of S. superba, but lower effect on wood basic density. The increment of crown and height was enhanced, and stem form was improved at sunny slope and down-slope, compared with shady slope and mid-slope, whereas DBH increment was higher in shady slope with higher soil water content. When S. superba were mixed with Chinese fir at appropriate ratio (such as the ratio of 1:3), stem form and the growth of DBH, height and crown all were improved significantly.The probability of stem forking (SF) of S. superba was fluctuating within 22.50%~35.75%, which mainly was single fork lower than 0.5m. In pure stands on sunny slope or down-slope and mixed stands (ratio of 1:3), the probability of stem forking was lower. Moreover, slope position had larger influence on stem fork formation than slope direction. The wood basic density was gradually decreased from pith to bark, and the reduction velocity of wood basic density from pith to bark was increased with the increasing of the diameter increment. The ring width was increased at first and followed by a reduction, with the largest wood formation speed during 5th to 15th rings.3. The result of provenance test demonstrated , variation in DBH, height, clear bole height, volume index and wood basic density among provenances was significant or very significant, of which the variation in volume index was the largest. A typical latitude variation pattern was found for growth traits and wood basic density of S.superba, and the local temperature of provenances was the main climatic factor which led to the variation, as the provenance came from the lower latitudes and higher temperature region, its height, diameter and volume index was greater, but wood basic density was smaller. Also, the traits were correlated, wood basic density was negatively correlated with growth traits. Besides the provenance effect, the effect of micro-environment of different repetition was also very significant, the provenances'growth of S.superba was smaller in the poor site condition, but the wood basic density showed an increasing tendency.Based on clustering of growth and wood basic density, the provenances of S.superba could be approximately divided into three provenance regions such as central, middle and northern provenance one. Meanwhile, seventeen superior provenances with superior growth and eleven provenances with both superior growth and wood properties were preliminarily selected by mean of volume index and wood basic density, and most of which originated from central provenance region of the Nanling-Wuyi Mountains.
Keywords/Search Tags:Schima superba, provenance, growth, stem form, wood basic density, natural phenotypic variation, provenance variation, provenance selection
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