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CHEN J H, YANG M, LIU Y D, et al. Comparative study on different structural adjustment models of artificial cypress plantation in hilly areas of central Sichuan[J]. Journal of Sichuan Forestry Science and Technology, 2022, 43(6): 11−17 doi: 10.12172/202206010003
Citation: CHEN J H, YANG M, LIU Y D, et al. Comparative study on different structural adjustment models of artificial cypress plantation in hilly areas of central Sichuan[J]. Journal of Sichuan Forestry Science and Technology, 2022, 43(6): 11−17 doi: 10.12172/202206010003

Comparative Study on Different Structural Adjustment Models of Artificial Cypress Plantation in Hilly Areas of Central Sichuan


doi: 10.12172/202206010003
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  • Corresponding author: 897629220@qq.com
  • Received Date: 2022-06-01
    Available Online: 2022-09-22
  • Publish Date: 2022-12-30
  • Two structural adjustment and transformation models of artificial cypress plantation in hilly areas of central Sichuan, that is, the “strip cutting + replanting” model (with the cutting-strip zone and reserved zone were 8m, and the replanted broad-leaved trees were Alnus cremastogyneToona sinensisCinnamomum camphoraCamptotheca acuminata), the “ecological thinning” model (the thinning intensity was 25%~30% in standing volume), the control stand (no cutting treatment) and the natural secondary oak-cypress mixed forest were taken as the research objects, the biodiversity, tree growth, coverage of shrubs and herbs, and the number of regenerated seedlings were analyzed. The results showed that: (1) The oak-cypress mixed forest had the highest tree layer richness and Shannon-Wiener diversity index, followed by the “strip cutting + replanting” model. The richness of shrubs and herbs were the highest in oak-cypress mixed forest, followed by the “ecological thinning” model. The shrub diversity index was the highest in the “ecological thinning” model, followed by the oak-cypress mixed forest. The Shannon-Wiener diversity index of the herbaceous species was the highest in oak-cypress mixed forest, followed by the “ecological thinning” model. However, the species richness and diversity index of the tree, shrub and herb layer of the control stand were the lowest. (2) The average DBH of trees was in the order of the “ecological thinning” model > the “strip cutting + replanting” model > oak-cypress mixed forest > control, and the average tree height was ranked as: the oak-cypress mixed forest > the “strip cutting + replanting” model > the “ecological thinning” model > control. (3) The first and the second highest coverage of shrubs and herbs were the “strip cutting + replanting” model and the oak-cypress mixed forest, and the lowest was the control. (4) In terms of regenerated seedlings under the forest, the largest number was in the oak-cypress mixed forest, and the least was in the control. But, there was little difference between the “strip cutting + replanting” model and the “ecological thinning” model. (5) The forest management plan for the artificial cypress plantation in the hilly areas of central Sichuan should be scientifically formulated according to different management objectives, and multi-functional management approach should be carried out so as to perform its multiple benefits.
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Comparative Study on Different Structural Adjustment Models of Artificial Cypress Plantation in Hilly Areas of Central Sichuan

doi: 10.12172/202206010003
  • 1. Sichuan Key Laboratory of Ecological Restoration and Conservation for Forest and Wetland, Sichuan Academy of Forestry, Chengdu 610081, China
  • 2. Liangshan Modern Forestry Industry Development Guidance Service Center, Xichang 615000, China
  • 3. College of Earth Science , Chengdu University of Technology, Chengdu 610059, China
  • Corresponding author: 897629220@qq.com

Abstract: Two structural adjustment and transformation models of artificial cypress plantation in hilly areas of central Sichuan, that is, the “strip cutting + replanting” model (with the cutting-strip zone and reserved zone were 8m, and the replanted broad-leaved trees were Alnus cremastogyneToona sinensisCinnamomum camphoraCamptotheca acuminata), the “ecological thinning” model (the thinning intensity was 25%~30% in standing volume), the control stand (no cutting treatment) and the natural secondary oak-cypress mixed forest were taken as the research objects, the biodiversity, tree growth, coverage of shrubs and herbs, and the number of regenerated seedlings were analyzed. The results showed that: (1) The oak-cypress mixed forest had the highest tree layer richness and Shannon-Wiener diversity index, followed by the “strip cutting + replanting” model. The richness of shrubs and herbs were the highest in oak-cypress mixed forest, followed by the “ecological thinning” model. The shrub diversity index was the highest in the “ecological thinning” model, followed by the oak-cypress mixed forest. The Shannon-Wiener diversity index of the herbaceous species was the highest in oak-cypress mixed forest, followed by the “ecological thinning” model. However, the species richness and diversity index of the tree, shrub and herb layer of the control stand were the lowest. (2) The average DBH of trees was in the order of the “ecological thinning” model > the “strip cutting + replanting” model > oak-cypress mixed forest > control, and the average tree height was ranked as: the oak-cypress mixed forest > the “strip cutting + replanting” model > the “ecological thinning” model > control. (3) The first and the second highest coverage of shrubs and herbs were the “strip cutting + replanting” model and the oak-cypress mixed forest, and the lowest was the control. (4) In terms of regenerated seedlings under the forest, the largest number was in the oak-cypress mixed forest, and the least was in the control. But, there was little difference between the “strip cutting + replanting” model and the “ecological thinning” model. (5) The forest management plan for the artificial cypress plantation in the hilly areas of central Sichuan should be scientifically formulated according to different management objectives, and multi-functional management approach should be carried out so as to perform its multiple benefits.

  • 森林的多功能经营强调森林是一种多资源、多效益的综合体,符合可持续发展战略的需求[1]。森林具有多种功能是全世界的共识,《联合国千年生态系统评估报告》将森林的功能分为4大类,即供给、调节、文化、支持。在林分层次上同时实现上述4类功能中的2个以上功能为经营目标的就被认为是多功能森林经营[2-4]。川中丘陵区地处亚热带地区,现存植被主要为上世纪80—90年代为改善生态环境和解决农民薪材问题营造的人工柏木纯林和由桤柏混交林退化而来的柏木纯林[5]。由于密度过大,树种单一,林下植被稀疏,林分的水土保持等生态功能不能充分发挥。针对该区域的人工柏木林,国内专家进行了大量的研究,主要集中在群落结构和多样性[6-7]、结构调整[8-10]等方面。对于柏木林分的结构调整,大多集中在单一方式研究,多种经营模式的对比鲜见报道。本文以“生态疏伐”改造林分、“带状改造+补阔”林分、自然演替林分(对照,不改造)以及处理演替阶段的天然次生栎柏混交林4种林分作为研究对象,对植被构成、结构特征与生物多样性的变化、林木生长、林下天然更新状况等进行对比分析,以期为该区域的人工柏木林多功能经营提供科学依据,从而指导经营单位对其进行结构调整和质量精准提升。

    • 研究区位于四川盆地中部的盐亭县、剑阁县、简阳市、金堂县、阆中市等地,地处亚热带湿润季风气候区,四季分明,降雨主要集中在每年的5~10月。年均雨量1 000 mm 以上,年均气温17℃ ,日照数1 300 h~1 400 h,无霜期 300 d 以上。土壤类型以紫色土和老冲积黄壤为主,少部分为姜石黄壤和灰白砂土[6]。现存植被主要是上世纪 70~80 年代长江防护林建设工程营建的人工柏木纯林和由人工桤柏混交林演变而来的柏木纯林。另有少量松柏混交(Pine-Cypress)、栎柏混交(Oak-Cypress)次生林[5]

    2.   研究方法
    • 选择了不同改造模式的林分(见表1)。其中,栎柏混交林(I)样地位于剑阁县、盐亭县、金堂县、简阳市。“带状改造+补阔”改造(II)林分位于盐亭县林山乡,于2010年改造,采伐带与保留带均为8m。补植的阔叶树种为2年生桤木(Alnus cremastogyne)、香椿(Toona sinensis)、香樟(Cinnamomum camphora)、喜树(Camptotheca acuminata),补植株行距均为2 m×3 m。“生态疏伐”改造(III)林分位于盐亭县、阆中市,于2012年改造,经过两次疏伐,疏伐强度分别为按蓄积25%~30%、15%~20%,疏伐后按自然状态经营。对照林分(CK,不改造)分别位于剑阁县、金堂县、简阳市。同一类型林分的样地设置时考虑坡度、海拔、坡向、土壤类型、土层深度等基本条件保持一致,并根据地形条件设置20 m×20 m、10 m×10 m、10 m×20 m、20 m×30 m 4种规格,共计39个样地。在每个样地的四角及中间各设置1个2 m×2 m的灌木样方,在灌木样方内设置1 m×1 m的草本样方。

      代码
      Code
      林分类型
      Stand type
      样地个数
      Number of plots
      面积/m2
      Area /m2
      郁闭度
      Canopy density
      平均胸径/cm
      Mean DBH /cm
      平均树高/m
      Average tree height /m
      I栎柏混交林
      oak-cypress mixed forest
      1243000.40~0.7514.43±3.269.42±1.33
      II“带状改造+补阔”改造林分
      “strip cutting + replanting” stand
      936000.50~0.6012.82±2.489.37±1.35
      III“生态疏伐”改造林分
      “ecological thinning” stand
      925000.50~0.7012.38±2.049.48±0.97
      CK对照林分(不改造)
      Control stand
      927000.75~0.9011.16±3.389.29±1.29

      Table 1.  Basic information of sample plots

    • 对样地内胸径5 cm以上的乔木进行每木检尺,记录种名、胸径、树高、冠幅等;灌木记录种名、株(丛)数、平均高、盖度等;草本记录种名、平均高、盖度等。对样地内胸径小于5 cm,树高小于2 m的记录为幼苗,树高大于2 m的记录为幼树,记录全部幼树、幼苗的种名、高、株数等。

    • 将野外记录的数据录入WPS office 表格,建立数据文件,进行统计分析。采用重要值作为测定多样性的指标。丰富度采用样地内的物种数,多样性选用Shannon-Wiener指数,均匀度采用Pielou群落均匀度指数,优势度采用Simpson优势度指数。方差分析和多重比较(LSD检验)在IBM SPSS Statistics 20中进行(α=0.05)。制图选用WPS office软件。各指数计算公式参见文献[11-12]

    3.   结果与分析
    • 调查结果表明,4种林分共收集到种子植物70科、103属133种。其中乔木17科、20属22种,灌木38科、46属54种,草本29科、46属57种。从乔木层看,样地内出现频度较高的树种有桤木、女贞(Ligustrum lucidum)、化香树(Platycarya strobilacea )、黄连木(Pistacia chinensis)、麻栎(Quercus acutissima )。灌木出现频度较高的种有菝葜(Smilax china)、黄荆(Vitex negundo)、 铁仔(Myrsine africana)、 野蔷薇(Rosa multiflora)、烟管荚蒾(Viburnum utile)。草本出现频度较高的种有凤尾蕨(Pteris cretica)、金星蕨(Parathelypteris glanduligera)、栗褐苔草(Carex brunnea)、团羽铁线蕨(Adiantum capillus-junonis)。

      不同林分的生物多样性差异较大(见表2)。从乔木层来看,物种丰富度和多样性由大到小排列为栎柏混交林>“带状采伐+补阔”改造林分>“生态疏伐”改造林分>对照。灌木层和草本则表现不同规律。从物种丰富度来说,灌木层:以栎柏混交林最高,其次是“生态疏伐”改造林分,最低的是改造林分。从Shannon-Wiener指数来看,“生态疏伐”改造林分最高,其次是栎柏混交林,最低的是对照林分;草本层:物种丰富度的规律与灌木层一致,Shannon-Wiener指数以栎柏混交林最高,其次是“生态疏伐”改造林分。各林分乔、灌、草优势度按大小排列为“生态疏伐”改造林分>对照>栎柏混交林>“带状采伐+补阔”改造林分、“带状采伐+补阔”改造林分>对照>栎柏混交林>“生态疏伐”改造林分、“生态疏伐”改造林分>对照>“生态疏伐”改造林分>栎柏混交林。

      林分
      Stand type
      乔木 Trees灌木 Shrubs草本 Herbs
      SH'CJswSH'CJswSH'CJsw
      I142.09360.17900.7933403.06380.07200.8306463.46120.04180.9040
      II112.06720.17540.8620222.50310.13970.8098242.28860.17150.7201
      III71.44560.42580.7212343.23370.05000.9170292.88880.082000.8579
      CK30.95620.34560.7426111.78390.11280.8234132.47820.08640.9146
        注:S:丰富度;H':Shannon-Wiener指数;C:Simpson优势度指数;Jsw:Pielou群落均匀度指数。
        Note: S: richness; H': Shannon-Wiener index; C: Simpson dominance index; Jsw: Pielou community evenness index.

      Table 2.  Biodiversity of different stands

    • 不同林分柏木的生长情况见图1。可以看出,平均树高以“生态疏伐”改造林分最大,对照林分最小,但4个林分差异不大。方差分析和多重比较(LSD)表明,栎柏混交林柏木高生长仅与“生态疏伐”改造林分差异显著(P<0.05),“带状采伐+补阔”改造林分与其他3种林分均差异不显著(P>0.05),“生态疏伐”改造林分与栎柏混交林和对照林分差异显著(P<0.05)。柏木平均胸径以栎柏混交林占较大优势,分别比“带状采伐+补阔”改造林分、“生态疏伐”改造林分、对照林分多9.98%、12.53%、15.10%。方差分析和多重比较(LSD)表明,栎柏混交林柏木平均胸径与“带状采伐+补阔”改造林分差异不显著(P>0.05),与“生态疏伐”改造林分、对照林分差异均显著(P<0.05)。“生态疏伐”改造林分、对照林分、“带状采伐+补阔”改造林分3种林分的柏木平均胸径差异均不显著(P>0.05)。

      Figure 1.  Growth status of cypress in different stands

    • 不同林分林下灌、草盖度见图2。4种林分灌、草盖度按大小排列均表现为“带状采伐+补阔”改造林分>栎柏混交林>“生态疏伐”改造林分>对照林分。“带状采伐+补阔”改造林分的灌木和草盖度分别比栎柏混交林、“生态疏伐”改造林分、对照林分高24.32%、29.39%、152.41%和37.40%、39.31%、85.75%。方差分析和多重比较(LSD)表明,“带状采伐+补阔”改造林分的灌、草盖度与其他3种林分均存在显著差异(P<0.05)。栎柏混交林的灌木、草本盖度与“生态疏伐”改造林分差异不显著(P>0.05)。“生态疏伐”改造林分的灌木盖度与对照林分差异显著(P<0.05),草盖盖度差异不显著(P>0.05)。

      Figure 2.  Coverage of shrubs and herbs in different stands

    • 林下幼苗更新成功与否直接影响或制约着群落物种组成和生态系统平衡与稳定[13]。适宜的林分郁闭度能改善林内光照、温湿条件,增加环境异质性[12],有利于新物种的进入。调查表明(见图3),林下更新幼(树)苗数量以栎柏混交林占绝对优势,达到了1 328株·hm-2,分别是“带状采伐+补阔”改造林分、“生态疏伐”改造林分、对照林分的1.64倍、1.66倍、7.03倍。“带状采伐+补阔”改造林分林下更新幼(树)苗状况与“生态疏伐”改造林分差异不大,但远远高于对照林分,前者是后者的4.29倍。“生态疏伐”改造林分的林下更新幼(树)苗是对照林分的4.23倍。从高度级分布来看,栎柏混交林的林下更新幼(树)苗主要集中在30~100 cm,占全部更新幼(树)苗的50%以上;“带状采伐+补阔”改造林分和对照林分的林下更新幼(树)苗高度主要集中在200 cm以上,特分别占全部更新幼(树)苗的80.49%、92.10%;“生态疏伐”改造林分的林下更新幼(树)苗高度以100~200 cm为主。

      Figure 3.  Natural regeneration of different stands

      不同林分林下更新幼(树)苗的种类有所不同(见表3),种类数量表现为栎柏混交林>“生态疏伐”改造林分>“带状采伐+补阔”改造林分>对照。从主要更新幼(树)苗的种类来看,低郁闭度的林分,由于林隙增多,林下光热条件得以改善,因此一些阳性树种进入。如“带状采伐+补阔”改造林分增加了强阳性树种—构树(Broussonetia papyrifera),而“生态疏伐”改造林分则除了构树外,还有黄连木(Pistacia chinensis)、桑树(Morus alba)等阳性树种,也进入了像麻栎(Quercus acutissima)此类的中性树种。郁闭度高的对照林分,由于密度过大,更新幼(树)苗主要是麻栎、女贞(Ligustrum lucidum)等中性树种或耐阴性树种。

      林分类型及
      更新幼苗的数量
      Stand type and
      number of
      regenerated seedlings
      树种
      Tree species
      拉丁名
      Latin name
      频度
      Frequency
      林分类型及
      更新幼苗的数量
      Stand type and
      number of
      regenerated seedlings
      树种
      Tree species
      拉丁名
      Latin name
      频度
      Frequency
      I(21)柏木Cupressus funebris0.83喜树Camptotheca acuminata0.56
      麻栎Quercus acutissima0.75盐肤木Rhus chinensis0.56
      八角枫Alangium chinense0.42香椿Toona sinensis0.44
      黄连木Pistacia chinensis0.42III(16)女贞Ligustrum lucidum0.78
      枇杷Eriobotrya japonica0.42构树Broussonetia papyrifera0.67
      女贞Ligustrum lucidum0.33黄连木Pistacia chinensis0.44
      构树Broussonetia papyrifera0.25柏木Cupressus funebris0.33
      化香树Platycarya strobilacea0.25麻栎Quercus acutissima0.33
      II(12)柏木Cupressus funebris1.00桑树Morus alba0.33
      香樟Cinnamomum camphora0.89CK(9)柏木Cupressus funebris0.33
      桤木Alnus cremastogyne0.78女贞Ligustrum lucidum0.33
      构树Broussonetia papyrifera0.67麻栎Quercus acutissima0.22

      Table 3.  Species and frequency of main regeneration seedlings under the forest

    4.   结论及讨论
    • 提高人工商品林的质量,提高木材供给率,保持和发挥森林的多种生态和环境服务功能,是人工林经营中面临的一个重要问题[14]。林分结构在森林多功能经营技术中占有很重要的分量。一般认为,复层、混交、异龄的林分,由于其结构更趋向于原始天然林的结构,森林生态系统的丰富度越高,森林的多功能就能更好地发挥[15-17]。对于人工林的结构调整,主要有抚育间伐、更替改造、调整改造等方法[18-20]。抚育间伐是林分空间结构优化经营常用的手段。其实质是对森林的人为干扰来调整林分结构、降低林分密度,从而提高森林质量、增强森林的稳定性[19]。“带状采伐+补阔”是改造针叶纯林促进其天然更新的重要手段[20]。针对不同区域、不同林分进行抚育间伐改造的适宜强度和带状采伐改造的适宜宽度,得出了不同的研究成果[19-24]。本文选择两种改造模式作为研究对象,抚育间伐的强度首次是按蓄积25%~30%,第二次是15%~20%;“带状采伐+补阔”改造模式的采伐带和保留带的宽度均为8 m。

      栎柏混交林作为四川盆地丘陵区主要的天然次生林,是区域内森林演替过程中重要阶段的植被类型。有关研究已经表明,其各种生态功能明显优于人工柏木纯林[25-28]。本研究结论与之一致。栎柏混交林乔灌草物种丰富度、多样性指数、林下更新幼苗数量明显高于未改造过的人工柏木纯林,也基本上高于改造过的两种林分。从两种密度调控方式来看,与对照相比,物种丰富度、生物多样性、保留乔木生长量、灌草盖度、林下更新幼(树)苗数量均明显增加或提高,这与有关研究的结论是一致的[20-21,24]。但从本研究来看,“生态疏伐”和“带状采伐+补阔”对提升林分质量的效果有所差别。“带状采伐+补阔”改造方式由于在采伐带内补植了几种阔叶树,乔木层丰富度和多样性指数明显高于“生态疏伐”的,但由于采伐带内种植了乔木,林下空间变小,因而灌、草的丰富度和多样性低于后者。“带状采伐+补阔”改造方式林下灌、草盖度显著高于“生态疏伐”改造模式。促进保留乔木生长和林下更新幼(树)苗总数量情况来看二者之间差异均不显著。以上说明这两种方式均适合人工柏木林的结构调整。但从森林多功能经营来看,以增强林分水土保持功能、水源涵养功能、改善景观功能为目的可采用“带状采伐+补阔”改造方式;以增强林分水土保持功能、林木蓄积量为目的可采用“生态疏伐”改造方式。经营管理单位应科学编制多功能森林经营方案,评价森林资源,进行森林功能区划,制定森林经营方针与目标[1],以更好地经营、管理区域内的森林资源。

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