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檫木(Sassafras tzumu)又名檫树,樟科檫木属落叶乔木,主要分布于中国长江流域及以南地区。檫木材质优良,叶型奇特,树型美观,具有重要的经济价值和生态价值。近年,随着造林理念的变化,乡土和彩叶树种越来越受到重视,檫木造林具有广阔的前景。在福建等东南沿海地区,由于高温和强日照等因素影响,檫木裸根苗造林初期成活率偏低,造林三年苗木保存率仅65%左右,导致林分郁闭慢,影响了檫木造林成效。有关檫木造林技术研究主要集中在混交林营造、栽植密度、土壤立地条件影响、抚育和施肥管理等方面[1-8],同时一些造林技术有关文献指出檫木截干造林成活率高[9-10],适宜推广。虽然这些研究为檫木造林提供了重要理论指导,但这些报道文献一般为经验性总结或者是综述性质,没有试验数据支撑。有研究表明五角枫、构树、刺槐等树种[11-16]截干造林成活率提高25%以上,个别树种(如丝棉木)成活率提高80%以上,且生长表现优异,截干造林效果良好。在生产实践上也发现造林风折后的檫树更易成活,长势良好,因此设计檫木截干造林试验,研究截干造林对檫木造林成活率及生长量的影响程度,探讨造林效果,以期为檫木造林提供技术指导及理论支撑。
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由表1调查统计数据可知,檫木截干造林当年全部成活,成活率100%,第二年8月调查,3个样地共死亡6株,平均每个样地2株,平均成活率为98%。未截干造林当年10月底调查3个样地合计死亡54株,成活率平均为82%,第二年8月死亡数量累计达到74株,成活率平均为75.3%。由此可见,截干造林第一年100%成活,第二年成活率可提高30.15%。
调查时间 截干 未截干 保存株数 死亡株数 成活率/% 保存株数 死亡株数 成活率/% 2019 样地1 100 0 100 80 20 80 样地2 100 0 100 83 17 83 样地3 100 0 100 83 17 83 平均 100 0 100 82 18 82 2020 样地4 99 1 99 75 25 75 样地5 97 3 97 79 21 79 样地6 98 2 98 72 28 72 平均 98 2 98 75.3 24.6 75.3 Table 1. Statistical analysis on the survival rate of Sassafras tzumu in stem-cutting afforestation study
对两个年度造林成活率数据分别进行T检验(见表2),表明截干与未截干造林成活率差异显著,截干造林可大幅度提高檫木造林成活率。
年度 t Value Pr > |t| 2019 8.1 <.0001 2020 9.48 <.0001 Table 2. T test of survival rate of Sassafras tzumu in stem-cutting afforestation study
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对地径、树高和抽梢等性状进行方差分析,由表3可知,2019年地径、树高和抽梢性状均差异极显著,2020年地径和抽梢差异极显著,树高差异显著,截干造林对檫木的生长产生明显的影响。
时间 性状 DF F Value Pr > F 地径 1 34.6 <.0001 2019 树高 1 55.8 <.0001 抽梢 1 188.9 <.0001 地径 1 25.96 <.0001 2020 树高 1 4.59 0.0335 抽梢 1 37.55 <.0001 Table 3. Variance analysis results of Sassafras tzumu in stem-cutting afforestation study
(1)地径生长量差异分析
由表4可知,檫木截干造林当年(2019年)地径均值1.82 cm,未截干地径均值1.41 cm,截干造林地径生长量增加0.41 cm,增幅29.21%;造林第二年(2020年)地径均值2.26 cm,未截干地径均值1.76 m,地径生长量增加0.5 cm,增幅29%。可见,截干造林后地径生长量明显提高,截干促进了檫木地径的快速增长。
时间 截干情况 均值/cm Std Dev 最小值 最大值 增幅/% 2019 截干 1.82 0.492336 0.6 3 29.21 未截干 1.41 0.412314 0.7 2.6 2020 截干 2.26 0.757403 0.9 5.4 29 未截干 1.76 0.507258 0.8 2.9 Table 4. Ground diameter growth of Sassafras tzumu in stem-cutting afforestation study
(2)树高生长量差异分析
由表5可知,檫木截干造林当年(2019年)树高为0.74 m,未截干树高1 m,截干造林树高相比降幅26.32%;造林第二年(2020年)树高为1.07 m,未截干树高1.17 m,截干造林树高相比降幅8.86%。檫木截干造林第二年后树高均值还未超过未截干造林树高。但从檫木苗个体看,截干造林的苗高最高值已经高于未截干造林的最大苗高。造成这种情况的原因主要是由于截干后苗木主干高度降低,导致整个苗木在树高生长起点上有较大的差距。但这不能说明截干对树高生长产生不利影响,相反截干还会进一步促进苗木的生长,具体影响还应还结合苗木年度抽梢生长量情况进行进一步分析确定。
时间 截干情况 均值/m Std Dev 最小值 最大值 增幅/% 2019 截干 0.74 0.28429 0.13 1.4 −26.32 未截干 1.00 0.164802 0.73 1.37 2020 截干 1.07 0.380518 0.13 1.77 −8.86 未截干 1.17 0.244987 0.76 1.71 Table 5. Tree height growth of Sassafras tzumu in stem-cutting afforestation study
(3)抽梢生长量差异分析
由表6可知,檫木截干造林当年(2019年)抽梢为0.55 m,抽梢变幅为0.11 m~1.19 m,未截干抽梢为0.17 m,抽梢变幅为0.02~0.45 m,截干造林抽梢增幅222.78%。造林第二年(2020年),截干抽梢量为0.33 m,抽梢变幅为0.010~1.21 m,未截干抽梢为0.17 m,抽梢变幅为0.02~0.43 m,截干造林抽梢增幅94.49%,截干造林抽梢增幅有逐年降低的趋势。综合两个年度的数据,檫木截干造林在造林初期能明显促进树干抽梢生长。
时间 截干情况 均值/m Std Dev 最小值 最大值 增幅/% 2019 截干 0.55 0.273012 0.11 1.19 222.78 未截干 0.17 0.109569 0.02 0.45 2020 截干 0.33 0.195622 0.01 1.21 94.49 未截干 0.17 0.09995 0.02 0.43 Table 6. Shoot growth of Sassafras tzumu in stem-cutting afforestation study
Study on Survival Rate and Growth of Sassafras Tzumu through Afforestation with Stem-cutting Method
doi: 10.12172/202009210005
- Received Date: 2020-09-21
- Available Online: 2021-01-18
- Publish Date: 2021-04-20
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Key words:
- Sassafras tzumu /
- Stem cutting /
- Afforestation /
- Survival rate
Abstract: The survival rate of afforestation with typical Sassafras tzumu is relatively low in the southeast coastal area. In this study, the stem of dry-rooted seedlings of Sassafras tzumu were cut off and afforested. The results showed that: (1) After two years of afforestation, the stem-cutting treatment significantly affected the survival rate, ground diameter, tree height, and growth indicators. Furthermore, except that the difference of tree height in the second year is significant, other indicators were extremely significant in different years and characteristics. (2) The stem-cutting treatment significantly improved the survival rate of Sassafras tzumu, which was 100% in the first year and 98% in the second year. Compared with the afforestation without stem-cutting treatment, the survival rate of the afforestation with stem-cutting was increased by 30.15%. (3) The stem-cutting treatment obviously promoted the growth of ground diameter, and the annual growth of ground diameter was over 29%. (4) The stem-cutting treatment greatly increased the shoot growth, with an increase of 222.78% in the first year and 94.49% in the second year. The results indicated that the stem-cutting afforestation had obvious effect in southeast coastal areas, and it was a promising afforestation method worth popularizing.