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Volume 36 Issue 3
Jun.  2023
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Differences in the Water-retention Function of Humus Layer between Two Typical Forests with Different Densities in the Qinling Mountains

  • Corresponding author: WANG Ya-ping, wangyaping0410@163.com
  • Received Date: 2022-07-20
    Accepted Date: 2022-07-29
  • Objective The differences in water-retention function of humus layer in typical forests with different densities in the Qinling Mountains were explored to provide basis for the vegetation construction. Methods Three plots with different densities (low, medium, and high) of Pinus tabulaeformis forest and Quercus aliena va.acuteseata forest were selected in Huoditang of Qinling Mountains. The indoor soaking and entropy weight methods were used to quantitatively analyze and comprehensively evaluate the water-retention function of humus layer. Results ①The thickness of humus in Pinus tabulaeformis and Quercus aliena va.acuteseata was 3.48~5.14 cm and 6.54~9.48 cm, respectively. The weight was the largest when the density was mediumwith 9.09 and 5.61 t·hm−2, respectively. The humus of Pinus tabulaeformis forest was mainly semi-decomposed layer (56.5%~60.55%), while that of Quercus aliena va.acuteseata forest was mainly undecomposed layer (63.58%~74.53%); ②The maximum water holding capacity of humus in Pinus tabulaeformis forest was found in medium density (24.55 t·hm−2), while that in Quercus aliena va.acuteseata forest was found in high density, which reached 17.8 t·hm−2 . The semi-decomposed layer of Pinus tabulaeformis forest and the undecomposed layer of Quercus acutissima forest played a major role in the absorption and retention of water by humus in the two forests; ③The accumulated water holding capacity of humus increased rapidly within 10 minutes after soaking, and the water holding growth rate of humus in Quercus aliena va.acuteseata forest was better than that of Pinus tabulaeformis forest. With the increase of soaking time, the water absorption rate of humus first decreased rapidly, then gradually decreased and tended to 0. The water holding rate(capacity), water absorption rate and soaking time of humus showed logarithmic and power function, respectively. Conclusion The water retention function of the semi-decomposed layer in Pinus tabulaeformis and undecomposed layer in Quercus aliena va.acuteseata forest can be complement each other, and the best performance of the Quercus aliena va.acuteseata forest can be reached when the density was 725 trees·hm−2. It is suggested to build a Pinus tabulaeformis Quercus aliena va.acuteseata mixed forest and control the density reasonably, so as to fully contribute to the hydrological function of humus.
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  • [1]

    SUN G, MCNULTY S G, AMATYA D M, et al. A comparison of the watershed hydrology of coastal forested wetlands and the mountainous uplands in the Southern US[J]. Journal of Hydrology, 2002, 263(1): 92-104.
    [2]

    ZHANG M F, WEI X H. Deforestation, forestation, and water supply[J]. Science, 2021, 371(6533): 990-991. doi: 10.1126/science.abe7821
    [3] 余新晓. 森林生态水文研究进展与发展趋势[J]. 应用基础与工程科学学报, 2013, 21(3):391-402. doi: 10.3969/j.issn.1005-0930.2013.03.001

    [4]

    SUN J, YU X, WANG H, et al. Effects of forest structure on hydrological processes in China[J]. Journal of Hydrology, 2018, 561: 187-199. doi: 10.1016/j.jhydrol.2018.04.003
    [5]

    BAI Y, ZHOU Y, DU J, et al. Effects of a broadleaf-oriented transformation of coniferous plantations on the hydrological characteristics of litter layers in subtropical China[J]. Global Ecology and Conservation, 2021, 25: e01400. doi: 10.1016/j.gecco.2020.e01400
    [6]

    SATO Y, KUMAGAI T, KUME A, et al. Experimental analysis of moisture dynamics of litter layers - The effects of rainfall conditions and leaf shapes[J]. Hydrological Processes, 2004, 18(16): 3007-3018. doi: 10.1002/hyp.5746
    [7] 袁秀锦, 肖文发, 潘 磊, 等. 马尾松林分结构对枯落物层和土壤层水文效应的影响[J]. 林业科学研究, 2020, 33(4):26-34.

    [8]

    DU J, NIU J, GAO Z, et al. Effects of rainfall intensity and slope on interception and precipitation partitioning by forest litter layer[J]. Catena, 2019, 172: 711-718. doi: 10.1016/j.catena.2018.09.036
    [9] 王盛琦, 傅文慧, 寇建村, 等. 黄土高原水蚀风蚀交错区沙地枯落物的水源涵养功能[J]. 水土保持通报, 2021, 41(5):30-37.

    [10] 吴 迪, 辛学兵, 赵明扬, 等. 北京九龙山不同林分枯落物及土壤水文效应[J]. 林业科学研究, 2014, 27(3):417-422.

    [11] 张淑兰, 韩 勇, 杨 盼, 等. 汉江上游不同林龄麻栎林枯落物的水文功能评价[J]. 生态环境学报, 2022, 31(1):44-51. doi: 10.16258/j.cnki.1674-5906.2022.01.006

    [12] 冯英杰, 刘佩伶, 刘效东, 等. 鼎湖山季风常绿阔叶林枯落物层自然含水量的长期动态变化[J]. 林业科学研究, 2022, 35(2):89-96. doi: 10.13275/j.cnki.lykxyj.2022.02.010

    [13]

    ZHU X, ZHANG W, JIANG X, et al. Conversion of primary tropical rainforest into rubber plantation degrades the hydrological functions of forest litter: Insights from experimental study[J]. Catena, 2021, 200: 105172. doi: 10.1016/j.catena.2021.105172
    [14] 周巧稚, 毕华兴, 孔凌霄, 等. 晋西黄土区不同密度刺槐林枯落物层水文生态功能研究[J]. 水土保持学报, 2018, 32(4):115-121.

    [15] 宣立辉, 佟彦国, 张 军, 等. 冀北山区油松人工林林分密度对枯落物层和土壤层水文特征的影响[J]. 林业与生态科学, 2019, 34(1):15-23.

    [16] 吴雪铭, 余新晓, 陈丽华, 等. 间伐强度对坝上樟子松林下持水能力的影响[J]. 应用生态学报, 2021, 32(7):2347-2354.

    [17] 孟庆旭, 张胜利, 李 侃, 等. 秦岭华山松林间伐强度对其水源涵养功能的影响[J]. 西北林学院学报, 2016, 31(2):1-7 + 85.

    [18] 任 成, 南夷非, 马晨歌, 等. 秦岭松栎混交林土壤水源涵养功能评价[J]. 陕西农业科学, 2016, 62(8):40-44.

    [19] 刘 宇, 郭建斌, 邓秀秀, 等. 秦岭火地塘林区3种土地利用类型的土壤潜在水源涵养功能评价[J]. 北京林业大学学报, 2016, 38(3):73-80.

    [20] 张洪江, 程金花, 史玉虎, 等. 三峡库区3种林下枯落物储量及其持水特性[J]. 水土保持学报, 2003, 17(3):55-58 + 123.

    [21] 赵 鹏, 马佳明, 李艳茹, 等. 太行山典型区域不同林分类型枯落物水文效应[J]. 水土保持学报, 2020, 34(5):176-185.

    [22]

    VAN STAN II J T, Coenders-Gerrits M, Dibble M, et al. Effects of phenology and meteorological disturbance on litter rainfall interception for a Pinus elliottii stand in the Southeastern United States[J]. Hydrological Processes, 2017, 31(21): 3719-3728. doi: 10.1002/hyp.11292
    [23] 刘少冲, 段文标, 赵雨森. 莲花湖库区几种主要林型枯落物层的持水性能[J]. 中国水土保持科学, 2005, 3(2):81-86.

    [24]

    CUI Y, PAN C, ZHANG G, et al. Effects of litter mass on throughfall partitioning in a Pinus tabulaeformis plantation on the Loess Plateau, China[J]. Agricultural and Forest Meteorology, 2022, 318: 108908. doi: 10.1016/j.agrformet.2022.108908
    [25]

    WU G, ZHANG M, LIU Y, et al. Litter cover promotes biocrust decomposition and surface soil functions in sandy ecosystem[J]. Geoderma, 2020, 374: 114429. doi: 10.1016/j.geoderma.2020.114429
    [26] 徐 娟, 余新晓, 席彩云. 北京十三陵不同林分枯落物层和土壤层水文效应研究[J]. 水土保持学报, 2009, 23(3):189-193.

    [27]

    DON A, KALBITZ K. Amounts and degradability of dissolved organic carbon from foliar litter at different decomposition stages[J]. Soil Biology and Biochemistry, 2005, 37(12): 2171-2179. doi: 10.1016/j.soilbio.2005.03.019
    [28] 马晓至, 毕华兴, 王珊珊, 等. 晋西黄土区典型林分枯落物层水文生态特性研究[J]. 水土保持学报, 2020, 34(6):77-83 + 88.

    [29] 王 玲, 赵广亮, 周红娟, 等. 八达岭林场不同密度油松人工林枯落物水文效应[J]. 生态环境学报, 2019, 28(9):1767-1775.

    [30] 王忠禹, 黄土丘陵区典型植被枯落物分布特征及其水文效应[D]. 杨凌, 西北农林科技大学, 2019.

    [31] 陈 婷, 郗 敏, 孔范龙, 等. 枯落物分解及其影响因素[J]. 生态学杂志, 2016, 35(7):1927-1935.

    [32] 段文标, 刘少冲, 陈立新. 莲花湖库区水源涵养林水文效应的研究[J]. 水土保持学报, 2005, 19(5):28-32.

    [33]

    XIA L, SONG X, FU N, et al. Effects of forest litter cover on hydrological response of hillslopes in the Loess Plateau of China[J]. Catena, 2019, 181: 104076. doi: 10.1016/j.catena.2019.104076
    [34] 罗 航, 何介南, 康文星, 等. 湘南红壤区互叶白千层人工林枯落物层及土壤水源涵养能力研究[J]. 中南林业科技大学学报, 2021, 41(5):102-109 + 132.

    [35] 高 迪, 郭建斌, 王彦辉, 等. 宁夏六盘山不同林龄华北落叶松人工林枯落物水文效应[J]. 林业科学研究, 2019, 32(4):26-32. doi: 10.13275/j.cnki.lykxyj.2019.04.004

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Differences in the Water-retention Function of Humus Layer between Two Typical Forests with Different Densities in the Qinling Mountains

    Corresponding author: WANG Ya-ping, wangyaping0410@163.com
  • 1. School of Tourism, Resources and Environment, Ankang University, Ankang 725000, China
  • 2. Academician and Expert Workstation of Shaanxi Association for Science and Technology, Ankang 725000, China

Abstract:  Objective The differences in water-retention function of humus layer in typical forests with different densities in the Qinling Mountains were explored to provide basis for the vegetation construction. Methods Three plots with different densities (low, medium, and high) of Pinus tabulaeformis forest and Quercus aliena va.acuteseata forest were selected in Huoditang of Qinling Mountains. The indoor soaking and entropy weight methods were used to quantitatively analyze and comprehensively evaluate the water-retention function of humus layer. Results ①The thickness of humus in Pinus tabulaeformis and Quercus aliena va.acuteseata was 3.48~5.14 cm and 6.54~9.48 cm, respectively. The weight was the largest when the density was mediumwith 9.09 and 5.61 t·hm−2, respectively. The humus of Pinus tabulaeformis forest was mainly semi-decomposed layer (56.5%~60.55%), while that of Quercus aliena va.acuteseata forest was mainly undecomposed layer (63.58%~74.53%); ②The maximum water holding capacity of humus in Pinus tabulaeformis forest was found in medium density (24.55 t·hm−2), while that in Quercus aliena va.acuteseata forest was found in high density, which reached 17.8 t·hm−2 . The semi-decomposed layer of Pinus tabulaeformis forest and the undecomposed layer of Quercus acutissima forest played a major role in the absorption and retention of water by humus in the two forests; ③The accumulated water holding capacity of humus increased rapidly within 10 minutes after soaking, and the water holding growth rate of humus in Quercus aliena va.acuteseata forest was better than that of Pinus tabulaeformis forest. With the increase of soaking time, the water absorption rate of humus first decreased rapidly, then gradually decreased and tended to 0. The water holding rate(capacity), water absorption rate and soaking time of humus showed logarithmic and power function, respectively. Conclusion The water retention function of the semi-decomposed layer in Pinus tabulaeformis and undecomposed layer in Quercus aliena va.acuteseata forest can be complement each other, and the best performance of the Quercus aliena va.acuteseata forest can be reached when the density was 725 trees·hm−2. It is suggested to build a Pinus tabulaeformis Quercus aliena va.acuteseata mixed forest and control the density reasonably, so as to fully contribute to the hydrological function of humus.

  • 森林生态系统在涵养水源、蓄水保土、固碳增汇及调节气候等方面发挥着关键作用[1-3]。在不同地形、气候和植被条件下,林冠层、枯落物层及土壤层对降水的截留和再分配、地表径流及蒸散发等过程发挥的作用有别[4]。其中枯落物层在拦蓄降水、防止土壤溅蚀和减少水分蒸发等方面有着重要作用[5-7]。受气候条件、时间尺度、树种和立地条件等因素影响,枯落物蓄积量及持水功能差异较大[8-10]。目前研究集中在某一地区多个树种或同一树种不同林龄阶段的枯落物及土壤持水功能差异上[11-13],而针对典型林分不同密度时的枯落物持水功能差异研究较少[14]。此外,已有研究证实不合理密度会影响水源涵养功能,强调适宜密度对提高森林水文功能的重要性[15-16]

    秦岭作为我国中部的重要生态屏障及南水北调中线工程的水源地,在保障区域生态安全和社会经济持续发展方面有重要作用。20世纪60年代,该区森林被大量砍伐,现存森林主要是恢复的天然次生林,近年来出现生长滞缓、地力衰退等问题[17],亟待调控改造以提升水源涵养功能。有学者探讨了间伐对华山松(Pinus armandii Franch.)林水源涵养功能的影响,指出间伐20%时的水源涵养效能最佳[17]。油松(Pinus tabulaeformis Carr.)林和锐齿栎(Quercus aliena var.acuteseata Maxim. ex Wenz.)林是秦岭地区的主要森林类型,近些年来由于缺乏管理,普遍存在衰退问题。尽管大量学者探讨了该区多个典型林分的水源涵养功能差异[18-19],然而较少研究秦岭地区不同密度的油松林和锐齿栎林枯落物水文功能差异,尚不清楚合理林分密度。因此,本文在秦岭火地塘林区选择了不同密度的油松林和锐齿栎林样地,定量测定枯落物层的厚度、组成、蓄积量和持水性能,通过熵权法探究枯落物层持水能力最佳的林分类型和密度,以期为该区水源涵养林可持续经营等提供理论依据。

    • 本研究区位于陕西省宁陕县火地塘林场,也是陕西秦岭森林生态系统国家野外科学观测研究站所在地,地处秦岭南坡,北亚热带北缘, 33º18′~33º28′ N, 108º21′~108º39′ E,研究区总面积约2 037 hm2,海拔1 470~2 473 m。林区气候类型属于暖温带湿润山地气候,多年平均降水量1 023 mm,多集中在7—9月,年均气温12 ℃。林区内沟道纵横,地形较陡峻,平均坡度30º。土壤主要为花岗岩母质发育起来的山地棕壤,土层较薄,平均厚度约50 cm。区域内森林覆盖率93.8%,植被类型具有由暖温带向亚热带过渡的特征,现有森林主要是天然次生林,建群树种主要有锐齿栎、油松、华山松、光皮桦(Betula luminifea H. Winkl.)、巴山冷杉(Abies fagesii Franch.)等,森林质量总体较高,野生动植物资源丰富。

    • 2022年3至4月,在充分勘查后,在远离道路且人为扰动较小的区域,分别选择油松林和锐齿栎林的3个不同密度样地。在每个样地中随机选择10株林木测定胸径,并随机选择3个样点人工打钻采集0~50 cm深度土层样品,并用烘干法测定其土壤水分状况。此外,调查记录样地编号、地理位置(经纬度)、海拔、坡度、郁闭度等基本信息,具体见表1

      森林样地
      Sample stands
      密度
      Density/
      (trees·hm−2)
      样地编号
      Sample plot number
      坡度
      Slope/(°)
      坡向
      Aspect
      海拔
      Altitude/m
      树龄
      Tree
      age/a
      平均胸径
      Average diameterat
      breast height/cm
      郁闭度
      Canopy
      density
      平均土壤含水量
      Mean soil
      water content/%
      油松林1450YS45010阳坡1 7604525.74 ± 3.030.6526.33
      油松林2700YS70010阳坡1 7054525.32 ± 2.260.7024.37
      油松林31 250YS125010阴坡1 7654524.97 ± 2.500.7522.14
      锐齿栎林1475RCL47528阳坡1 5903023.67 ± 1.970.7038.92
      锐齿栎林2725RCL72530阳坡1 5983022.37 ± 1.780.7529.77
      锐齿栎林31 250RCL125035阳坡1 6203018.91 ± 1.580.8030.10
      注:数据为平均值 ± 标准差,YS和RCL分别表示油松林和锐齿栎林。
        Notes: The values were mean ± standard deviation, YS and RCL indicate Pinus tabulaeformis forest and Quercus aliena va.acuteseata forest, respectively.

      Table 1.  Basic information of the sampling site in this study

    • 在每块样地随机选择3个50 cm × 50 cm的样方,根据枯落物分解腐烂程度[20],分别收集半分解层和未分解层的全部枯落物,装入塑料袋做好标记带回实验室;同时在样方附近随机选择10个不同位置点,用钢尺测定未分解层及半分解层厚度并做好记录。在室内,用电子天平称取枯落物鲜质量,然后装入档案袋,放入85 ℃烘箱烘干至质量恒定,称量干质量,计算枯落物自然含水率及单位面积枯落物蓄积量。

    • 采用室内浸泡法测定枯落物持水能力,在尽量保持枯落物原状条件下,将烘干后枯落物样品装入已知质量的细孔尼龙网袋内,置于装满水的容器中,分别在累积浸水5、10、20、30、40 min和1、1.5、2、4、6、8、12、24 h时取出,静置至不滴水后迅速称量质量并记录。每次样品湿质量与干质量之差即为该时段的枯落物持水量,其中24 h后为最大持水量。持水量与浸水时间的比值为该时段枯落物持水速率,并进一步计算枯落物的持水率和拦蓄率(量),相关计算公式参见文献[11, 21]

    • 为直观比较,采用熵权法对不同密度油松林和锐齿栎林枯落物水文功能进行综合评价[9]。首先,对选择的水文功能指标进行标准化处理,包括枯落物的厚度、蓄积量、最大持水率、最大持水量、有效拦蓄率和有效拦蓄量6个指标,通过极值法标准化处理,然后根据公式计算各指标的熵值及权重,进而评价不同样地枯落物的水源涵养功能差异,具体计算过程如下:

      (假设Sij = 0时,$ {S_{ij}}\ln {S_{ij}}{\text{ = }}0 $i = 1,2,…,mj = 1,2,…,n

      式中:i表示样地类型(m = 6),j表示评价指标(n = 6);rij为样地i在第j个指标上的实测值;rij(max)rij(min)分别为第j个指标中的极大值和极小值;RijSij分别为样地i在第j个指标上的标准化值和贡献度;k为常数,Gi为各指标的熵值,Wj为各评价指标的权重,Vi为最终评价得分。

    • 采用Excel 2016进行数据整理,利用SPSS 26.0进行数据统计分析,采用单因素方差分析方法比较不同密度及不同林分类型枯落物的持水功能差异,事后检验采用Tukey检验,采用Origin 2016软件作图。

    2.   结果与分析
    • 表2可看出,两个林分不同密度样地的枯落物层厚度呈显著差异(p < 0.05),而蓄积量则无明显差异。对同一密度水平样地来讲,尽管锐齿栎林枯落物厚度大于油松林,但是二者的总蓄积量却差别不大,甚至在低密度时的总蓄积量显著低于油松林( p < 0.05)。就不同林分样地而言,油松林枯落物总厚度变化在3.48~5.14 cm,呈现为随密度增加而增大,且中高密度的枯落物层厚度显著高于低密度林地(p < 0.05),其中半分解层的厚度变化在2.02~3.25 cm,而未分解层厚度较小。在锐齿栎林样地中,枯落物层厚度变化在6.54~9.48 cm,中密度的枯落物层厚度最大,其次为高密度和低密度样地,枯落物以未分解层为主,半分解层厚度均小于1 cm。在枯落物蓄积量方面,油松和锐齿栎两个林分类型均以中密度样地最大,分别达9.09、5.61 t·hm−2,而高密度油松林和低密度锐齿栎林样地的蓄积量最小。进一步分析表明,油松林枯落物蓄积量以半分解层为主,占56.5%~60.55%,而锐齿栎林以未分解层为主(63.58%~74.53%)。

      采样地
      Sample plots
      枯落物厚度
      Thickness of
      humus layer/cm
      总厚度
      Total
      thickness/
      cm
      蓄积量
      Weight of humus/
      (t·hm−2)
      总蓄积
      Total weight/
      (t·hm−2)
      占蓄积量比例
      Proportion of
      the weight/%
      未分解层
      Undecomposed
      layer
      半分解层
      Semi-decomposed
      layer
      未分解层
      Undecomposed
      layer
      半分解层
      Semi-decomposed
      layer
      未分解层
      Undecomposed
      layer
      半分解层
      Semi-decomposed
      layer
      YS4501.46 ± 0.35 Bb2.02 ± 0.31 Ab3.48 ± 0.55 Bb2.71 ± 0.45 B3.99 ± 0.85 A6.70 ± 1.30 A40.3659.64
      YS7001.72 ± 0.39 Bab3.32 ± 0.43 Aa5.04 ± 0.53 Ba3.59 ± 0.52 B5.50 ± 1.86 A9.09 ± 2.3839.4560.55
      YS12501.89 ± 0.18 Ba3.25 ± 0.60 Aa5.14 ± 0.53 Ba2.76 ± 0.31 B3.58 ± 0.91 A6.34 ± 1.2243.5056.50
      RCL4756.54 ± 0.69 Ab0.18 ± 0.05 Bb6.54 ± 0.69 Ab3.28 ± 0.28 A1.58 ± 0.41 B4.86 ± 0.69 B67.5232.48
      RCL7259.48 ± 1.23 Aa0.42 ± 0.19 Ba9.48 ± 1.23 Aa3.57 ± 0.61 A2.04 ± 0.45 B5.61 ± 1.0563.5836.42
      RCL12507.08 ± 0.49 Ab0.36 ± 0.06 Bab7.44 ± 0.49 Ab4.16 ± 0.91 A1.42 ± 0.09 B5.58 ± 0.9974.5325.47
      注:数据为平均值 ± 标准差,小写字母不同表示不同密度间差异显著,大写字母不同表示相同密度不同林分间差异显著(p < 0.05),未标注字母表示无显著性差异,下同。
       Notes: The values were mean ± standard deviation. Different lowercase letters within a column indicate significant difference among the different densities, and different uppercase letters indicate significant difference among different forest types (p< 0.05), and no letters indicate no significant difference, the same below.

      Table 2.  Thickness and weight of humus layer in Pinus tabulaeformis and Quercus aliena var.acuteseata forest with different densities

    • 两类林分不同枯落物组分的自然含水率均存在明显差异,其中未分解层介于9.30%~55.81%,半分解层则为18.85%~102.59%,除低密度油松林之外,其他样地下半分解层枯落物的自然含水率均高于未分解层(表3)。6个样地的枯落物总最大持水量变化在14.41~24.55 t·hm−2,中密度油松林(24.55)>高密度锐齿栎林(17.8)> 低密度锐齿栎(15.94)> 中密度锐齿栎(15.76)> 低密度油松林(15.15)> 高密度油松林(14.41)。3个密度油松林的枯落物半分解层最大持水率均高于未分解层,而锐齿栎样地未呈现明显差别。

      采样地
      Sample plots
      自然含水率
      Natural moisture content/%
      最大持水率
      Maximum water
      holding rate/%
      最大持水量
      Maximum water holding
      capacity/(t·hm−2)
      总最大持水量
      Total maximum water
      holding capacity/
      (t·hm−2)
      未分解层
      Undecomposed
      layer
      半分解层
      Semi-decomposed
      layer
      未分解层
      Undecomposed
      layer
      半分解层
      Semi-decomposed
      layer
      未分解层
      Undecomposed
      layer
      半分解层
      Semi-decomposed
      layer
      YS45055.81 ± 53.4139.30 ± 29.39162.44 ± 1.83 271.25 ± 26.314.39 ± 0.7610.75 ± 1.8715.15
      YS70020.70 ± 8.0565.12 ± 5.90238.79 ± 15.08290.48 ± 14.158.56 ± 1.4815.99 ± 5.8424.55
      YS125034.47 ± 7.85102.59 ± 49.97185.93 ± 14.62259.12 ± 30.345.13 ± 0.279.28 ± 1.9814.41
      RCL47510.00 ± 1.5231.58 ± 17.89311.78 ± 13.32361.74 ± 62.4310.23 ± 1.245.71 ± 1.1215.94
      RCL7259.30 ± 3.5928.38 ± 14.43305.76 ± 28.02237.66 ± 12.7710.90 ± 1.674.85 ± 0.7915.76
      RCL125012.54 ± 1.0718.85 ± 7.19320.84 ± 21.40313.41 ± 19.2713.34 ± 3.794.45 ± 0.0217.80

      Table 3.  Water holding capacity of humus in Pinus tabulaeformis and Quercus aliena var.acuteseata with different densities

    • 图1可看出,油松林枯落物未分解层的最大拦蓄率和有效拦蓄率均在中密度最高,分别为217.83%和182.05%;在低密度的拦蓄率则最低,且与中密度呈显著差异( p < 0.05);而半分解层的枯落物拦蓄率对3个密度无显著差异。对锐齿栎林样地,未分解层枯落物的最大拦蓄率和有效拦蓄率在3个密度之间无显著差异,其值变化在298.16~305.47%和252.04~257.77%;而半分解层枯落物的拦蓄率则在中密度最低,其最大拦蓄率和有效拦蓄率分别为211.10%和175.18%。

      Figure 1.  Maximum interception rate (capacity) and effective interception rate (capacity) of humus in different sample plots

      此外,油松林枯落物的最大拦蓄量及有效拦蓄量的最大值均出现在中密度,其未分解层的最大拦蓄量为7.83 t·hm−2,显著高于高密度和低密度样地(p < 0.05)。锐齿栎林样地未分解层枯落物拦蓄量随着密度增加而增大,半分解层的拦蓄量则无明显的密度差异,其最大拦蓄量和有效拦蓄量分别为4.19~5.17 t·hm−2和3.51~4.32 t·hm−2

    • 不同密度油松林和锐齿栎枯落物的持水过程见图2。可以看出,6个样地的未分解层和半分解层枯落物的累计持水率(量)均在浸泡10 min内迅速增加,然后增速有所降低,2 h后开始缓慢增加,直至24 h达到最大值。

      Figure 2.  Change of water holding rate, water holding capacity and absorption rate with soaking time in different sample plots

      从吸水速率来看,在浸水10 min内,未分解层和半分解层枯落物均有较大的瞬时吸水速率,其值约在30~61.74 t·hm−2·h−1,20 min后开始迅速降低,在2 h以后逐渐减少并接近于0。未分解层枯落物的持水率和持水量均为锐齿栎林高于同时段的油松林,且高密度锐齿栎林的值最大。半分解层枯落物的持水率,在各样地之间分布无明显规律,而持水量表现为油松林优于锐齿栎林,中密度油松林的持水量最佳,锐齿栎林半分解枯落物层持水量随浸水时间的变化在3个密度之间无明显差别。

      表4可以看出,枯落物的持水率、持水量与浸水时间呈明显的对数关系(y=aln(t) + b,y为持水率/%或持水量/(t·hm−2),t为浸水时间/h,a为系数,b为常数项),拟合关系的决定系数R2为0.867~0.965。枯落物的吸水速率与浸水时间符合幂函数关系(y=atby为枯落物的吸水速率/(t·hm−2·h−1),a为方程系数,b为指数),拟合关系式的决定系数R2为0.943~0.992。

      采样地
      Sample plots
      枯落物层
      Humus layer
      持水率
      Water holding rate
      持水量
      Water holding capacity
      吸水速率
      Water absorption rate
      拟合方程
      Fitted equation
      R2 拟合方程
      Fitted equation
      R2 拟合方程
      Fitted equation
      R2
      YS450 未分解 y=25.03ln(t) + 98.74 0.946 y=0.669ln(t) + 2.71 0.944 y=2.416t−0.724 0.975
      半分解 y=30.13ln(t) + 194.62 0.917 y=1.217ln(t) + 7.72 0.916 y=7.397t−0.931 0.991
      YS700 未分解 y=33.31ln(t) + 150.08 0.963 y=1.199ln(t) + 5.40 0.961 y=4.962t−0.756 0.980
      半分解 y=32.88ln(t) + 203.32 0.925 y=1.831ln(t) + 11.13 0.930 y=10.665t−0.825 0.991
      YS1250 未分解 y=30.06ln(t) + 115.74 0.945 y=0.826ln(t) + 3.16 0.947 y=2.76t−0.690 0.943
      半分解 y=30.84ln(t) + 193.53 0.867 y=1.101ln(t) + 6.88 0.868 y=6.548t−0.823 0.985
      RCL475 未分解 y=38.76ln(t) + 195.98 0.964 y=1.281ln(t) + 6.43 0.965 y=6.04t−0.792 0.992
      半分解 y=42.86ln(t) + 247.72 0.940 y=0.675ln(t) + 3.82 0.945 y=3.609t−0.808 0.988
      RCL725 未分解 y=39.82ln(t) + 192.19 0.960 y=1.409ln(t) + 6.82 0.959 y=6.310t−0.774 0.984
      半分解 y=30.28ln(t) + 158.96 0.938 y=0.615ln(t) + 3.22 0.935 y=2.999t−0.788 0.984
      RCL1250 未分解 y=38.86ln(t) + 210.97 0.961 y=1.650ln(t) + 8.79 0.961 y=8.258t−0.797 0.988
      半分解 y=39.11ln(t) + 205.61 0.938 y=0.55ln(t) + 2.921 0.937 y=2.726t−0.789 0.979

      Table 4.  Relationship between water holding rate, water holding capacity and absorption rate and soaking time of humus layer

    • 前面的分析表明,不同森林样地的枯落物厚度、蓄积量、持水性能等指标分布存在差别。为了更直观了解不同样地的枯落物持水能力情况,用熵权法对6个指标进行综合评价(表5)。可以看出,不同密度油松林的枯落物持水功能表现为中密度>高密度>低密度,锐齿栎林在不同密度之间相差不大,其中以中密度表现最佳,综合得分83.38。整体来看,在密度接近情况下,锐齿栎林枯落物持水功能优于油松林。

      样地
      Sample
      plots
      厚度
      Thickness of
      humus
      总蓄积量
      Weight of
      humus
      最大持水率
      Maximum water
      holding rate
      最大持水量
      Maximum water
      holding capacity
      有效拦蓄率
      Effective interception
      rate
      有效拦蓄量
      Effective interception
      capacity
      评价得分
      Evaluation
      score
      YS4500.002.612.297.111.851.0514.92
      YS70015.346.003.7119.665.325.0055.02
      YS125016.322.102.336.130.000.0026.88
      RCL47530.090.005.578.1712.002.8058.63
      RCL72559.001.064.067.938.662.6783.38
      RCL125038.941.025.2810.6511.663.7271.28

      Table 5.  Comprehensive evaluation score of hydrological function of humus in different sample plots

    3.   讨论
    • 枯落物层对土壤保持和水源涵养功能至关重要,不但可减弱降雨对地表的冲刷,还起到拦截蓄水作用[22],因此枯落物蓄积量变化可直接影响水源涵养能力。枯落物蓄积量及其水文功能受林分类型、立地条件、气候及季节等因素影响而动态变化[23-25]。在本研究中,锐齿栎林枯落物层厚度显著高于油松林,这可能是因阔叶与针叶的差异,但枯落物蓄积量为油松林较大,这与他人[26]研究结果一致,因针叶枯落物富含油脂不易分解,阔叶枯落物表皮较薄和缺乏保护所以分解较快[27]。此外,有学者在分析不同林龄麻栎枯落物蓄积量时发现,枯落物蓄积量除林龄外更多受林分密度及累积时间影响[11]。本研究中,油松林和锐齿栎林的枯落物蓄积量均随林分密度增加呈“单峰型”变化,这和前人研究一致[15],但蓄积量有别[28-29],原因可归结为两点:一是林分密度增加会降低林内光照和温度,利于枯落物积累,但当密度过高时会加剧林木个体竞争和导致生长缓慢及凋落物减少[14];二是枯落物蓄积量会随植被生长阶段呈现季节性变化[30],本研究测样时间为春季,枯落物可能已被分解或受冬季风力影响转移到别处[31],这也说明枯落物蓄积量季节变化特征还有待进一步研究。

    • 枯落物持水量和持水率是反映枯落物水文调节能力的重要指标,体现了枯落物的持水容量及吸收地表径流的能力,有效拦蓄率则反应了枯落物对降雨的拦截能力[3, 32],其大小与枯落物的蓄积量、结构组成、立地条件及分解程度等有关[9, 33]。段文标等人分析发现,受植被类型影响,不同林型及荒草地枯落物层的厚度及储量分布有别,其持水功能也有所不同[23, 32]。一般来讲,阔叶林凋落物因其叶面积大,更容易分解,有更大吸水速率和持水率[21]。本研究中不同密度的油松林和锐齿栎林枯落物的持水过程呈现一致规律,即累积持水量在10 min内迅速增加,2 h后缓慢增加直到24 h后保持恒定,相应吸水速率则在在10 min内较高,随后迅速降低并接近与0,其中同一时段的锐齿栎林未分解枯落物的持水性能优于油松林,这进一步证实了前人研究[21, 34]。不管油松林还是锐齿栎林,枯落物的降水拦蓄有效时间主要在2 h内,原因是枯落物初期干燥导致吸水速率较高,随时间延长枯落物吸水量逐渐接近其最大值,因此吸水速率快速降低[34]。特别地,油松林半分解枯落物的持水能力优于未分解层,而锐齿栎林相反,说明油松林半分解枯落物在降水拦截中发挥着重要功能,而锐齿栎林主要依赖其疏松的未分解层,这和前人研究结论一致[15]。这表明,油松林和锐齿栎的半分解层和未分解层枯落物在降水拦截中可以作用互补。在降雨初期,枯落物通过迅速吸水来有效拦截降雨,从而保护土壤免受雨滴击溅侵蚀,枯落物蓄积量较高林分的持水能力更明显,可在短时间内快速吸水,有效发挥水源涵养功能。此外,枯落物的持水率、持水量及吸水速率均与浸水时间有较好的对数和幂函数关系,这和已有研究一致[11, 23, 34-35]。本研究还综合评价了两类典型林分不同密度时的枯落物持水能力,发现锐齿栎林优于油松林,且当锐齿栎林密度为725株·hm−2时最佳。因此建议调整林分结构,将纯林逐渐改造为混交林,这样可实现两个树种的枯落物持水性能互补,充分发挥水源涵养功能。

    4.   结论
    • 在陕西秦岭火地塘林区,油松林和锐齿栎林的枯落物层厚度分别为3.48~5.14 cm和6.54~9.48 cm,高密度油松林和中密度锐齿栎林的最大;枯落物蓄积量均为中密度时最大,分别为9.09、5.61 t·hm−2,其组成对油松林以半分解层为主(56.5%~60.55%),对锐齿栎林以未分解层为主(63.58%~74.53%)。

      两种森林的枯落物最大持水量变化在14.41~24.55 t·hm−2,对油松林是中密度的最大,主要贡献者是半分解层;对锐齿栎林则是高密度的最大,主要贡献者是未分解层。枯落物累积持水率在浸水10 min内迅速增加,且锐齿栎林的增速大于油松林;枯落物吸水速率随浸水时间增加先快速降低,在2 h后则逐渐降低并趋于0。枯落物的持水率(量)和吸水速率与浸水时间分别具有很好的对数和幂函数关系。

      通过熵权法综合评价,锐齿栎林枯落物的持水功能优于油松林,且以密度725株·hm−2时最佳。建议未来进行松栎混交造林,并且合理控制密度,以充分发挥其水文功能。

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