• 中国中文核心期刊
  • 中国科学引文数据库(CSCD)核心库来源期刊
  • 中国科技论文统计源期刊(CJCR)
  • 第二届国家期刊奖提名奖
Volume 34 Issue 3
Jun.  2021
Article Contents
Turn off MathJax

Citation:

Effects of Thinning Intensity on Soil Quality and Growth of Teak Plantation

  • Corresponding author: ZHOU Zai-zhi, zzzhoucn@21cn.com
  • Received Date: 2020-09-17
    Accepted Date: 2021-03-03
  • Objective To explore the effects of thinning intensity on the growth of teak, on soil physicochemical properties and on enzyme activity. Method Taking 15 years old pure forest of teak (Tectona grandis) as trial object, four thinning intensity treatments, including low, moderate, heavy thinning and the control were set. The growth, soil properties and enzyme activities of teak plantation were measured 3.5 years after thinning, and the difference of these indexes with different intensity treatment was analyzed. Redundant analysis method (RDA) was used to study the relationship between tree growth, soil enzyme activity and soil property. Result The effects of thinning on soil physicochemical properties and enzyme activities were showed mainly in 0-20 cm soil layer. The soil moisture content of the surface soil increased and soil pH reduced after thinning. The contents of soil organic matter and alkali-hydrolyzed nitrogen was positively correlated with the intensity of thinning treatment, In 0-20 cm soil layer, the organic matter contents under moderate and heavy thinning increased by 18.2% and 19.0% compared with the control, and the alkali-hydrolyzed nitrogen content was respectively 15.7% and 16.6% higher than that of the control. The contents of total nitrogen and exchangeable calcium also increased after thinning. The activity of invertase and acid phosphatase in 0-20 cm soil layer was significantly enhanced by thinning, but there was no significant difference in urease and catalase contents. The average breast-height diameter and the volume of individual trees of teak plantation increased with the intensity of thinning treatment, and the stand basal area and volume were higher than those of the control. Under heavy thinning treatment, the annual increment of growth indexes of teak was the largest and significantly higher than that of the control, while both the individual volume and stand volume increment were higher than of the control by 80.0% and 90.2% respectively. There was a positive correlation between soil organic matter, available phosphorus and tree growth indexes. Soil water holding capacity, density and total porosity were the main environmental factors affecting soil enzyme activity. Conclusion Thinning can improve soil nutrient and water status, promotes the growth of teak, and the productivity of forest land can increase obviously. Thinning significantly enhances the C cycle-related invertase activity and increases the activity of N, P cycle-related enzymes. Total nitrogen, soil bulk density are the key factors affecting enzyme activity. The suitable thinning intensity of 15-year-old teak plantation is 40%-45%.
  • 加载中
  • [1]

    Peng D, Yang G, Liu J, et al. Effects of thinning intensity on understory vegetation and soil microbial communities of a mature Chinese pine plantation in the Loess Plateau[J]. Science of the Total Environment, 2018, 630(15): 171-180.
    [2] 张文雯, 韩海荣, 程小琴, 等. 间伐对华北落叶松人工林土壤活性有机碳含量及酶活性的影响[J]. 应用生态学报, 2019, 30(10):3347-3355.

    [3] 祁金虎, 杨会侠, 丁国泉, 等. 抚育间伐对辽东山区人工红松林土壤物理性质及持水特性的影响[J]. 东北林业大学学报, 2016, 44(5):48-51.

    [4] 马芳芳, 贾 翔, 赵 卫, 等. 间伐强度对辽东落叶松人工林土壤理化性质的影响[J]. 生态学杂志, 2017, 36(4):971-977.

    [5] 沈雅飞. 除灌、采伐处理对马尾松人工林土壤有机碳及其相关过程的影响[D]. 北京: 中国林业科学研究院, 2018.

    [6]

    Wang W W, Dumroese D P, Lv R H, et al. Soil enzyme activities in Pinus tabuliformis (Carriére) plantations in northern China[J]. Forests, 2016, 7(6): 1-12.
    [7]

    Zhou Z H, Wang C K, Jin Y, et al. Impacts of thinning on soil carbon and nutrients and related extracellular enzymes in a larch plantation[J]. Forest Ecology and Management, 2019, 450: 117523. doi: 10.1016/j.foreco.2019.117523
    [8]

    Lull C, Bautista I, Lidón A, et al. Temporal effects of thinning on soil organic carbon pools, basal respiration and enzyme activities in a Mediterranean Holm oak forest[J]. Forest Ecology and Management, 2020, 464: 118088. doi: 10.1016/j.foreco.2020.118088
    [9] 沈国舫, 翟明普. 森林培育学[M]. 北京: 中国林业出版社, 2001: 264-265.

    [10] 姚甲宝, 曾平生, 袁小平, 等. 间伐强度对木荷–萌芽杉木中龄混交林生长和林分结构的影响[J]. 林业科学研究, 2017, 30(3):511-517.

    [11] 囤兴建. 间伐对杨树人工林生产力和养分循环的影响[D]. 南京: 南京林业大学, 2013.

    [12] 商添雄, 韩海荣, 程小琴, 等. 华北落叶松人工林生长对抚育间伐的响应及其与土壤因子的关系[J]. 林业科学研究, 2019, 32(6):40-47.

    [13] 龚固堂, 牛 牧, 慕长龙, 等. 间伐强度对柏木人工林生长及林下植被的影响[J]. 林业科学, 2015, 51(4):8-15.

    [14]

    Zhou L L, Cai L P, He Z M, et al. Thinning increases understory diversity and biomass, and improves soil properties without decreasing growth of Chinese fir in southern China[J]. Environmental Science and Pollution Research, 2016, 23(23): 24135-24150. doi: 10.1007/s11356-016-7624-y
    [15] 王春胜, 唐 诚, 赵志刚, 等. 桂西南地区西南桦中龄林生长对间伐和施肥的响应[J]. 中南林业科技大学学报, 2018, 38(5):28-32.

    [16] 张金文. 巨尾桉大径材间伐试验研究[J]. 林业科学研究, 2008, 21(4):464-468.

    [17]

    Albaugh T J, Fox T R, Rubilar R A, et al. Post–thinning density and fertilization affect Pinus taeda stand and individual tree growth[J]. Forest Ecology and Management, 2017, 396: 207-216. doi: 10.1016/j.foreco.2017.04.030
    [18]

    Yahya A Z, Saaiffudin K A, Hashim M N. Growth response and yield of plantation grown teak (Tecatona grandis) after low thinning treatments at Pagoh, Peninsular Malaysia[J]. Journal of Tropical Forest Science, 2011, 23(4): 453-459.
    [19]

    Zhou Z Z, Liu S C, Liang K N, et al. Growth and mineral nutrient analysis of teak (Tectona grandis) grown on acidic soils in south China[J]. Journal of Forestry Research, 2017, 28(3): 503-511. doi: 10.1007/s11676-016-0324-0
    [20] 周树平, 梁坤南, 杜 健, 等. 不同密度柚木人工林林下植被及土壤理化性质的研究[J]. 植物研究, 2017, 37(2):200-210.

    [21]

    Kanninen M, Pérez D, Montero M, et al. Intensity and timing of the first thinning of Tectona grandis plantations in Costa Rica: results of a thinning trial[J]. Forest Ecology and Management, 2004, 203(1-3): 89-99. doi: 10.1016/j.foreco.2004.07.054
    [22]

    Quintero–Méndez M A, Jerez–Rico M. Optimizing thinnings for timber production and carbon sequestration in planted teak (Tectona grandis L. f.) stands[J]. Forest Systems, 2019, 28(3): 1-14.
    [23] 中国科学院南京土壤所. 土壤理化分析[M]. 上海: 科学技术出版社, 1978: 62–132.

    [24] 关松荫. 土壤酶及其研究法[M]. 北京: 农业出版社, 1987: 274–328.

    [25] 邝炳朝. 柚木良种选育及配套技术[R]. 广州: 中国林业科学研究院热带林业研究所, 1996.

    [26] 顾振宽, 杜国祯, 朱炜歆, 等. 青藏高原东部不同草地类型土壤养分的分布规律[J]. 草业科学, 2012, 29(4):507-512.

    [27] 许彦明. 抚育间伐对水曲柳落叶松混交林土壤氮矿化的影响[D]. 哈尔滨: 东北林业大学, 2014.

    [28] 朱书豪, 刘丽媛, 袁浩凌, 等. 稻田冬闲期土壤酶活性及理化性质对不同是施肥响应[J]. 中国农学通报, 2020, 36(36):50-57.

    [29]

    Zhang X C, Dippold M A, Kuzyakov Y, et al. Spatial pattern of enzyme activities depends on root exudate composition[J]. Soil Biology and Biochemistry, 2019, 133: 83-93. doi: 10.1016/j.soilbio.2019.02.010
    [30]

    Allison V J, Condron L M, Peltzer D A, et al. Changes in enzyme activities and soil microbial community composition along carbon and nutrient gradients at the Franz Josef chronosequence, New Zealand[J]. Soil Biology & biochemistry, 2007, 39(7): 1770-1781.
    [31]

    Xu Y X, Du A P, Wang Z C, et al. Effects of different rotation periods of Eucalyptus plantations on soil physiochemical properties, enzyme activities, microbial biomass and microbial community structure and diversity[J]. Forest Ecology and Management, 2020, 456: 1-10.
    [32] 潘秉林, 王振宇, 杨 梅, 等. 间伐对光皮桦人工林生长及土壤化学性质的影响[J]. 北华大学学报: 自然科学版, 2020, 21(3):398-404.

    [33] 全 锋, 周超凡, 段光爽, 等. 基于蓄积生长率的蒙古栎天然次生林抚育间伐研究[J]. 林业科学研究, 2020, 33(2):61-68.

  • 加载中
通讯作者: 陈斌, bchen63@163.com
  • 1. 

    沈阳化工大学材料科学与工程学院 沈阳 110142

  1. 本站搜索
  2. 百度学术搜索
  3. 万方数据库搜索
  4. CNKI搜索

Figures(2) / Tables(5)

Article views(4339) PDF downloads(67) Cited by()

Proportional views

Effects of Thinning Intensity on Soil Quality and Growth of Teak Plantation

    Corresponding author: ZHOU Zai-zhi, zzzhoucn@21cn.com
  • Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou 510520, Guangdong, China

Abstract:  Objective To explore the effects of thinning intensity on the growth of teak, on soil physicochemical properties and on enzyme activity. Method Taking 15 years old pure forest of teak (Tectona grandis) as trial object, four thinning intensity treatments, including low, moderate, heavy thinning and the control were set. The growth, soil properties and enzyme activities of teak plantation were measured 3.5 years after thinning, and the difference of these indexes with different intensity treatment was analyzed. Redundant analysis method (RDA) was used to study the relationship between tree growth, soil enzyme activity and soil property. Result The effects of thinning on soil physicochemical properties and enzyme activities were showed mainly in 0-20 cm soil layer. The soil moisture content of the surface soil increased and soil pH reduced after thinning. The contents of soil organic matter and alkali-hydrolyzed nitrogen was positively correlated with the intensity of thinning treatment, In 0-20 cm soil layer, the organic matter contents under moderate and heavy thinning increased by 18.2% and 19.0% compared with the control, and the alkali-hydrolyzed nitrogen content was respectively 15.7% and 16.6% higher than that of the control. The contents of total nitrogen and exchangeable calcium also increased after thinning. The activity of invertase and acid phosphatase in 0-20 cm soil layer was significantly enhanced by thinning, but there was no significant difference in urease and catalase contents. The average breast-height diameter and the volume of individual trees of teak plantation increased with the intensity of thinning treatment, and the stand basal area and volume were higher than those of the control. Under heavy thinning treatment, the annual increment of growth indexes of teak was the largest and significantly higher than that of the control, while both the individual volume and stand volume increment were higher than of the control by 80.0% and 90.2% respectively. There was a positive correlation between soil organic matter, available phosphorus and tree growth indexes. Soil water holding capacity, density and total porosity were the main environmental factors affecting soil enzyme activity. Conclusion Thinning can improve soil nutrient and water status, promotes the growth of teak, and the productivity of forest land can increase obviously. Thinning significantly enhances the C cycle-related invertase activity and increases the activity of N, P cycle-related enzymes. Total nitrogen, soil bulk density are the key factors affecting enzyme activity. The suitable thinning intensity of 15-year-old teak plantation is 40%-45%.

  • 间伐作为一种重要的森林经营措施,能够改变林内的小气候环境。林下光照、土壤温湿度的变化引起土壤性质和酶活性等的改变,且不同林分不同强度间伐效应不同。Dang等[1]对油松(Pinus tabuliformis Carrière)研究表明,土壤养分含量均随间伐强度的增加而增加。张文雯等[2]对华北落叶松(Larix principis-rupprechtii Mayr.)、祁金虎等[3]对红松(Pinus koraiensis Sieb.et Zucc.)林间伐研究得出,中度间伐有利于土壤养分的累积及土壤透气性和土壤湿度的改善。适当的间伐强度有利于土壤碳氮养分的积累[45]。土壤养分含量的变化与酶活性密切相关,土壤酶作为土壤中重要的生物活性物质,其活性直接影响土壤养分的循环、转化和利用。大量研究表明,间伐对土壤酶活性产生影响,但结论不一[68],缺少酶活性与土壤理化性质变化内在关系的研究。探究不同间伐强度土壤酶活性与土壤理化性质的关系,有助于了解不同间伐强度土壤质量的变化规律,从而揭示间伐对林木生长的作用机制。

    间伐调整了林分密度,进而缓解林木间的竞争,为保留木分配合理的营养空间[9]。适度间伐能够改善林木的生长条件,扩大林冠层的光照面积,明显促进胸径、冠幅和单株材积的增长[10],年平均生长量也随间伐强度的增加而增大[1112]。林分密度的减小,导致林分蓄积量下降,在柏木(Cupressus funebris Endl.)[13]和杉木(Cunninghamia lanceolata Hook.)[14]林分中,蓄积量随间伐强度的增加呈下降趋势,间伐后的西南桦(Betula alnoides Buch-Ham.)人工林林分蓄积量无显著变化[15],而巨尾桉(Eucalyptus grandis × E. urophylla Coppice)[16]、火炬松(Pinus taeda Linn.)[17]、柚木(Tectona grandis Linn. f.)[18]等人工林间伐后,林分蓄积量均有明显提高。间伐对林分蓄积的影响程度因树种、林龄、间伐强度、立地条件等的不同而异。

    柚木属马鞭草科高大乔木,材质优良,用途广泛,在国际市场上具有极高的经济价值。近年来,伴随优质柚木材需求的大幅度上升,国内人工林种植面积迅速增加[19]。柚木生长对立地条件要求较高,培育优质大径材周期较长,对密度的合理调控尤为重要。适宜的林分密度下柚木生长良好,而过高或过低的林分密度不利于其生长及土壤肥力的维持[20]。然而,在生产实践中面临高密度种植及管理等问题,致使国内柚木生长受限,林分质量和土壤养分含量偏低,柚木人工林可持续经营面临挑战。确立合理的间伐强度对促进柚木林分生长和改善林地质量至关重要。目前,国外对柚木人工林间伐的研究多集中在林木生长、材质、木材产量及C固定方面[2122],而国内对柚木间伐研究尚未见报道。本文以15年生的柚木人工林为研究对象,通过系列间伐处理,探究间伐后柚木生长及土壤理化性质和酶活性的差异,旨在为柚木大径材高效培育和立地管理提供基础数据和科学依据。

1.   试验地概况
  • 试验地位于云南省西双版纳傣族自治州勐腊县勐伴镇坝连龙村(101°36′40″ E,21°40′9″ N),属亚热带湿润季风气候,年平均气温21℃,≥ 10℃活动积温7 500℃以上,年降水量1 600~1 800 mm,平均相对湿度84%,6—10月为雨季。试验林地地貌类型以低山为主,海拔810~820 m,坡度15°~25°;土壤以砂壤土为主,土层深厚,pH值5.4。试验林为2000年营建的柚木纯林,初值密度900株·hm−2,保存率82%,林下植被主要有山芝麻(Helicteres angustifolia Linn.)、蔓生莠竹(Microstegium vagans (Nees ex Steud) A.Camus)、淡竹叶(Lophatherum gracile Brongn.)、矛叶荩草(Arthraxon lanceolatus (Roxb.) Hochst.)等。

2.   研究方法
  • 2015年10月,于长势较均匀的15年生柚木纯林内铺设间伐试验。设置4个不同处理:轻度间伐(LT:15%~20%)、中度间伐(MT:30%~35%)、重度间伐(HT:40%~45%)和对照(CK:卫生伐),随机区组排列,3次重复,总计12个小区,每个小区面积0.067 hm2。间伐后林分的基本特征见表1

    处理
    Treatment
    平均胸径
    Mean DBH0/cm
    平均树高
    Mean H0 /m
    保留密度
    Density/(株·hm−2)
    CK18.48 ± 0.1916.86 ± 0.25665
    LT19.53 ± 0.2816.79 ± 0.58630
    MT20.04 ± 0.5117.17 ± 0.39485
    HT20.03 ± 0.5317.13 ± 0.34420
      注:CK,对照;LT,轻度间伐;MT,中度间伐;HT,重度间伐,下同。
      Notes: CK, control; LT, low thinning; MT, moderate thinning; HT, high thinning, the same as below.

    Table 1.  Growth of teak plantation before thinning

  • 2019年6月,对不同处理小区进行土壤采取,每个小区内随机设置3个土壤采样点,挖40 cm深的剖面,分别在0~20、20~40 cm土层,用环刀取原状土,带回实验室测定土壤密度、田间持水量、总孔隙度、毛管孔隙度和非毛管孔隙度[23]。采用多点混合取样法,每个土壤采样点用自封袋取散土,即将同一小区同一土层的3个土样等量混匀为一个混合样,去除土壤样品中的根系、石块等杂物,用四分法将土样分成两部分,一部分样品进行自然风干、过筛,用于土壤化学性质的测定;另一部分鲜土放置于4℃冰箱中保存,用于土壤酶活性的测定。

  • 采用水土比为2.5∶1的水溶液浸提–电位法测定pH;采用重铬酸钾氧化法测定有机质含量;采用HClO4-H2SO4消煮法测定全氮含量;采用碱解扩散法测定碱解氮含量;采用H2SO4-HCl法提取–钼锑抗比色法测定有效磷含量;采用乙酸铵浸提法–火焰光度计法测定速效钾含量;交换性钙、交换性镁含量采用乙酸铵提取–原子吸收分光光度法测定[23]

  • 碱皿扩散-HCl滴定法测定脲酶活性,以1 h后1 g土壤中NH3-N的毫克数表示;采用硫代硫酸钠滴定法测定蔗糖酶活性,以1 h后1 g土壤中0.1 mol·L−1 Na2S2O3的毫克数表示;采用高锰酸钾滴定法测定过氧化氢酶活性,以1 h后1 g土壤中0.1 mol·L−1高锰酸钾的毫克数表示;采用磷酸苯二钠-4-氨基安替比林比色法测定酸性磷酸酶活性,以1 h后1 g土壤中消耗的P2O5的毫克数表示[24]

  • 2019年6月,对每个小区内全部林木进行每木检尺,记录不同间伐强度下柚木树高(H1)、胸径(DBH1),计算平均单株材积(V1)、林分断面积(BA)和林分蓄积(V2),计算公式如下[25]

      式中:n为每个小区林木株数,N为林分每公顷保留木株数。

    间伐3.5 a后,计算各生长指标的年平均增量:

    年平均增量 = (2019年测定均值 − 2015年保留木均值)/3.5。

  • 采用SPSS25.0软件对单株林木和林分生长量以及土壤理化性质和酶活性进行单因素(one–way ANOVA)方差分析和最小显著差异法(LSD)多重比较,显著水平设置为α = 0.05。采用Canoco5.0软件,以林木生长量、土壤酶活性作为响应变量,土壤理化性质为解释变量进行冗余分析(RDA)。

3.   结果与分析
  • 表2可看出:随土层深度的增加,不同间伐强度处理的柚木林地土壤密度呈增大趋势(HT处理除外);MT、CK处理的0~20 cm和20~40 cm土层间土壤密度均差异显著(p < 0.05),而LT和HT处理的差异不显著(p > 0.05);4个处理中,MT处理的土壤密度最大,分别为1.29、1.36 g·cm−3。0~20 cm土层中,不同间伐强度的土壤密度均差异不显著,仅MT和HT 处理的土壤密度高于CK。

    间伐强度
    Thinning intensity
    土层深度
    Soil depth /cm
    土壤密度
    Soil density/(g·cm−3
    土壤含水率
    Soil water content/%
    田间持水量
    Filed moisture capacity/%
    总孔隙度
    Total porosity/%
    毛管孔隙度
    Capillary porosity /%
    非毛管孔隙度
    Non–capillary porosity/%
    CK0~201.23 ± 0.01 Ba22.26 ± 0.46 Ab33.06 ± 0.67 Aa53.51 ± 0.68 Aa42.63 ± 0.44 Aa10.88 ± 0.76 Aa
    20~401.30 ± 0.02 Aab21.68 ± 0.47 Aa33.06 ± 0.69 ABa51.10 ± 0.78 Bab42.26 ± 0.31 Aa8.84 ± 0.63 ABb
    LT0~201.22 ± 0.03 Aa22.59 ± 0.33 Aab33.40 ± 1.15 Aa54.07 ± 1.30 Aa41.93 ± 0.42 Aa12.14 ± 1.25 Aa
    20~401.31 ± 0.03 Aab20.05 ± 1.03 Ba30.76 ± 2.01 Aa50.64 ± 2.07 Aab41.07 ± 0.47 Aa9.57 ± 1.78 Aab
    MT0~201.29 ± 0.02 Ba24.63 ± 0.65 Aa31.90 ± 0.80 Aa51.46 ± 0.89 Aa42.40 ± 0.60 Aa9.06 ± 1.00 Aa
    20~401.36 ± 0.03 Aa22.08 ± 0.77 Ba28.86 ± 0.89 Ba48.51 ± 0.96 Ba40.67 ± 0.61 ABa7.85 ± 0.80 Ab
    HT0~201.26 ± 0.03 Aa23.36 ± 0.99 Aab32.57 ± 1.01 Aa52.62 ± 1.24 Aa42.31 ± 0.28 Aa10.31 ± 1.39 Aa
    20~401.24 ± 0.03 Ab21.83 ± 0.98 Aa31.73 ± 1.05 Aa53.05 ± 1.13 Aa40.81 ± 0.63 ABa12.24 ± 1.01 Aa
      注:同列不同小写字母代表不同间伐强度间差异显著(p < 0.05),同列不同大写字母代表同一间伐强度不同土层间差异显著(p < 0.05),下同(表3图1)。
      Notes: Different small letters in the same column meant significant difference among different thinning intensities at 0.05 level. Different capital letters in the same column significant difference among different soil layers under the same thinning intensity at 0.05 level,the same as below (Table3, Fig.1).

    Table 2.  Soil physical properties of teak plantation after 3.5 years of thinning

    间伐后0~20 cm土层的土壤含水率呈增大趋势,MT处理的土壤含水率最大,为24.63%,且显著高于CK。随着土层深度的增加,各间伐强度的土壤含水率、田间持水量和毛管孔隙度均呈下降趋势。0~20 cm土层,不同间伐强度的土壤毛管孔隙度和非毛管孔隙度的变化差异均不明显。

  • 表3可看出:随土层深度的增加,不同间伐强度的土壤有机质、碱解氮、有效磷、交换性钙含量以及土壤pH值均显著降低(p < 0.05);0~20 cm土层的土壤有机质含量随间伐强度的增加而增大,LT、MT和HT处理分别比CK 提高了12.3%、18.2%和19.0%,其中,MT和HT处理与CK之间差异显著;与CK相比,间伐后,0~20 cm土层的土壤全氮含量均增加,其中,LT和HT处理的土壤全氮含量增幅较大,分别比CK提高了17.6%和17.2%;相同土层不同间伐强度的林分土壤全氮含量差异不显著(p > 0.05)。

    指标
    Index
    土层深度
    Soil depth/cm
    间伐强度 Thinning intensity
    CKLTMTHT
    有机质 SOM/(g·kg–10~2050.36 ± 2.70 Ab56.54 ± 1.74 Aab59.53 ± 3.19 Aa59.94 ± 1.03 Aa
    20~4027.32 ± 0.94 Ba23.34 ± 1.61 Ba24.55 ± 0.85 Ba25.98 ± 1.62 Ba
    全氮 TN/(g·kg–10~202.21 ± 0.15 Aa2.60 ± 0.05 Aa2.25 ± 0.23 Aa2.59 ± 0.23 Aa
    20~401.11 ± 0.06 Ba1.66 ± 0.47 Aa0.94 ± 0.21 Ba1.19 ± 0.10 Ba
    碱解氮 AN/(mg·kg–10~20165.00 ± 3.89 Ab172.37 ± 8.96 Ab190.84 ± 8.32 Aa192.33 ± 4.79 Aa
    20~4094.58 ± 3.26 Ba89.30 ± 4.23 Ba94.95 ± 12.60 Ba93.46 ± 5.98 Ba
    有效磷 AP/(mg·kg–10~209.20 ± 2.36 Aa5.49 ± 0.70 Aa5.79 ± 0.65 Aa8.33 ± 1.42 Aa
    20~401.02 ± 0.09 Ba0.59 ± 0.07 Ba0.90 ± 0.04 Ba1.42 ± 0.55 Ba
    交换性钙 ECa/(g·kg–10~202.62 ± 0.22 Aa2.84 ± 0.13 Aa3.01 ± 0.08 Aa2.99 ± 0.14 Aa
    20~401.39 ± 0.19 Ba1.34 ± 0.19 Ba1.54 ± 0.11 Ba1.47 ± 0.25 Ba
    交换性镁 EMg/(g·kg–10~200.46 ± 0.02 Aa0.46 ± 0.02 Aa0.46 ± 0.01 Aa0.47 ± 0.01 Aa
    20~400.41 ± 0.05 Aa0.37 ± 0.01 Ba0.41 ± 0.01 Aa0.39 ± 0.02 Ba
    pH值0~206.46 ± 0.10 Aa6.33 ± 0.09 Aa6.39 ± 0.10 Aa6.41 ± 0.11 Aa
    20~405.60 ± 0.12 Ba5.54 ± 0.08 Ba5.65 ± 0.09 Ba5.63 ± 0.08 Ba

    Table 3.  Effects of thinning on soil chemical properties of teak plantations

    0~20 cm土层的土壤碱解氮含量随间伐强度的增大而增加,其中,HT、MT处理与CK、LT处理差异均显著(p < 0.05),HT和MT处理的碱解氮含量分别比CK提高了16.6%和15.7%,比LT处理提高了11.6%、10.7%。LT处理碱解氮含量比CK增加了4.5%。0~20、20~40 cm土层土壤有效磷、交换性钙、交换性镁含量及pH值在不同间伐强度间均差异不显著。0~20 cm土层的土壤有效磷含量和pH值与CK 相比,均呈下降趋势,而交换性钙的含量增加。

  • 间伐改变了土壤酶活性,不同间伐强度对酶活性的影响不同。由图1可知:0~20 cm土层,不同间伐强度的土壤蔗糖酶活性均与CK差异显著,LT、MT、HT处理蔗糖酶活性比CK分别提高了117.3%、89.0%、90.0%,LT处理土壤酶活性最大,为2.23 mg·g−1·h−1;LT、MT、HT处理间蔗糖酶活性差异不显著。20~40 cm土层,CK蔗糖酶活性较高为1.70 mg·g−1·h−1,而LT、MT、HT处理的蔗糖酶活性均降低,LT处理的活性最低,为1.30 mg·g−1·h−1。0~20、20~40 cm土层的土壤过氧化氢酶和脲酶活性在不同强度间伐处理间的变化差异不显著(图1)。间伐后0~20 cm土层土壤酸性磷酸酶活性均不同程度的增加,其中,LT处理活性最高,分别比CK、MT、HT提高了19.0%、5.1%、4.7%。

    Figure 1.  Changes of soil enzyme activity with different thinning intensity

  • 表4可知:间伐3.5 a后,柚木的平均胸径和单株材积随间伐强度的增大而增加,其中,LT、MT、HT处理的平均胸径显著高于CK(p < 0.05),分别比CK提高了5.4%、9.3%、12.6%;MT、HT处理的平均单株材积比CK增加了21.1%,31.6%,而LT处理与CK差异不显著(p > 0.05)。间伐对保留木平均树高影响不大,MT和HT处理分别比CK仅提高了1.6%和6.1%。随间伐强度的增大,林分平均断面积和蓄积量呈增长趋势,仅HT处理显著高于CK;LT、MT和HT处理的林分断面积分别比CK提高了25.9%、19.0%、32.2%,林分蓄积分别提高了26.5%、21.6%、39.8%。

    处理 Treatment平均胸径 DBH1/cm平均树高 H1/m平均单株材积 V1/m3林分断面积 BA/(m2·hm–2)林分蓄积 V2/(m3·hm–2)
    CK19.69 ± 0.41 c19.47 ± 0.32 a0.38 ± 0.02 c19.54 ± 1.66 b236.94 ± 23.86 b
    LT20.76 ± 0.11 b19.40 ± 0.56 a0.43 ± 0.02 bc24.61 ± 0.66 ab299.80 ± 16.42 ab
    MT21.52 ± 0.36 ab19.78 ± 0.30 a0.46 ± 0.02 ab23.26 ± 1.97 ab288.18 ± 28.26 ab
    HT22.17 ± 0.30 a20.65 ± 0.53 a0.50 ± 0.03 a25.84 ± 1.01 a331.14 ± 31.65 a
      注:同列不同小写字母表示差异显著(p < 0.05),下同。
      Note: Different small litters in the same column are significantly different(p < 0.05), the same as below.

    Table 4.  Growth status of teak plantation after 3.5 years of thinning

    间伐前后柚木各生长指标增量的变化各不相同(表5),单株林木胸径、材积、林分断面积年均增量随间伐强度的增大呈增加趋势,不同间伐强度增量的高低顺序均为HT > MT > LT > CK,其中,HT处理下的增量显著高于CK(p < 0.05),分别提高了77.5%、80.0%、102.6%。不同间伐强度的树高增量,仅HT处理比CK显著增加了35.6%。

    处理
    Treatment
    胸径增量
    Diameter increment/cm
    树高增量
    Height increment/m
    单株材积增量
    Volume increment/m3
    林分断面积增量
    Basal area increment/m2
    林分蓄积增量
    Volume increment/m3
    CK0.40 ± 0.01 b0.87 ± 0.07 b0.030 ± 0.004 b0.77 ± 0.20 b18.72 ± 2.90 b
    LT0.41 ± 0.07 b0.87 ± 0.13 b0.035 ± 0.004 b0.99 ± 0.16 b24.19 ± 1.78 b
    MT0.49 ± 0.07 ab0.87 ± 0.07 b0.038 ± 0.001 b0.99 ± 0.09 b23.81 ± 1.22 b
    HT0.71 ± 0.08 a1.18 ± 0.09 a0.054 ± 0.002 a1.56 ± 0.14 a35.60 ± 2.80 a

    Table 5.  The averageannual incremental change of growth index inthinningtreatment

  • 分别以柚木5个生长指标的增量及0~20 cm土层4种酶活性指标为响应变量,以表征土壤理化性质的主要指标为解释变量,进行冗余分析。图2A表明:第1轴和第2轴共解释了柚木年均生长增量差异的98.80%。柚木5个生长指标均与土壤的AP、SOM、TN、AN指标密切相关,其中,△DBH、△HCB、△V与AP显著正相关,△HCB、△V与SOM、TN正相关,△DBH与SD负相关。AP和SOM为主要的影响因子。

    Figure 2.  Redundancy analysis of the effects of soil physicochemical on the growth increment and soil enzyme activities under different thinning intensities.

    图2B表明:0~20 cm层4种土壤酶活性差异在第1轴和第2轴的解释量分别为90.05%和3.17%,即2轴共解释土壤酶活性特征的93.22%,且主要由第1轴反应酶活性和环境因子的关系。由环境轴的长度及其与几种酶活性的夹角可知,酶活性主要与FMC、TOP、SD紧密相关,FMC与UR、IV、ACP、CAT四种酶均正相关,UR与pH显著正相关,与ECa、EMg正相关,而与SD负相关;ACP与TOP显著正相关,而与SD显著负相关;CAT与AN、SOM均负相关。

4.   讨论
  • 土壤有机质和有效养分含量直接反映了土壤的生产潜力。本研究中,柚木人工林间伐3.5 a后,林地0~20 cm土层土壤有机质、全氮、碱解氮含量均不同程度的提高,其中,土壤有机质和碱解氮含量随间伐强度的增加明显增大,这可能与C循环相关的酶活性有直接关系,间伐后土壤C含量和蔗糖酶活性的变化趋势一致,酶活性的提高,有利于土壤有机物质的分解与转化,促进土壤氮的矿化。土壤有机质含量的提高,表征土壤全氮含量会增加,因为土壤全氮的95%来源于土壤有机质[26]。土壤中全氮有80%以有机态的形式存在,间伐后土壤水分含量的提高,可能直接或间接的影响了土壤微生物群落和酶的活性,促进了土壤有机态氮向无机态氮的转化,进而提高了土壤碱解氮的含量[27]

    土壤酶作为表征土壤质量和健康状况的重要生物指标,参与土壤中的各种生物化学反应过程。本研究中,蔗糖酶、脲酶活性与土壤pH 呈显著正相关,这与朱书豪等[28]对土壤酶与pH相关性研究结果一致。柚木间伐后,土壤蔗糖酶活性显著增强,而脲酶活性也有所提升,且轻度、中度、重度间伐后的林分土壤pH值随着间伐强度的增加呈增大趋势。土壤pH的提高,促进了保留木细根的生长以及根系分泌物的增多[29],土壤酶活性增强,进而促进了柚木的生长。土壤酶活性的改变,可能与林内水热条件的改善和土壤有机物质含量的提高以及微生物的种类和数量增加有关[30],具体的原因还需进一步的研究。冗余分析得出,间伐后土壤酸性磷酸酶的活性与田间持水量和土壤总孔隙呈显著正相关,而与有效磷含量的相关性不明显,这与Xu等[31]“酶活性与土壤有效养分含量呈正相关关系”的结论不一致,可能与间伐时间、土壤质地等因素不同有关。可见,林地土壤酶活性的变化并不一定能完全解释间伐后土壤有效养分含量的改变。

    柚木间伐后,保留木的平均胸径和单株材积均随间伐强度的增大而增加,重度间伐处理年均增量最大,且与对照差异显著,这与对光皮桦(Betula luminifera H.Winkl.)[32]、西南桦[15]等间伐研究结论一致。间伐降低了林分密度,增加了光照强度,加之土壤物理状况的改善和土壤有机质及有效养分含量的提高,促使柚木的生长加快,特别是胸径和单株材积的生长。此外,间伐后林分断面积和蓄积及其年均增量均高于对照,弥补了林木株数的减少造成林分蓄积的下降,但这与全峰等[33]对蒙古栎(Quercus mongolica Fisch.exLedeb.)次生林研究结果不同,可能与树种、立地及间伐强度不同有关。间伐后,林下植被多样性及土壤微生物群落结构及功能的演变规律有待研究。

5.   结论
  • (1)间伐有利于改善林地表层土壤养分和水分状况,并有效促进保留木的生长,土壤有机质和有效氮含量是影响柚木人工林生长的关键因子。

    (2)间伐主要影响0~20 cm表层土壤酶的活性,间伐后的林分与未间伐林分相比,土壤蔗糖酶活性显著提高,脲酶、酸性磷酸酶和过氧化氢酶活性变化不明显;田间持水量和土壤密度及孔隙度是影响土壤酶活性的主要环境因子。

    (3)40%~45%的间伐强度更有利于柚木幼林的生长和土壤质量的改善。

Reference (33)

Catalog

    /

    DownLoad:  Full-Size Img  PowerPoint
    Return
    Return