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目前,二氧化碳(CO2)升高导致的全球变暖已成为人类生存所面临的重要生态问题,土壤呼吸作为大气最大的CO2排放源之一,已成为科学界研究的热点。土壤呼吸在陆地生态系统碳循环和碳收支中占有重要地位[1],其任何微小变化都将影响大气CO2的排放[2]。土壤作为森林生态系统中的最大碳库[3],其呼吸作用占森林生态系统碳排放的30%~80%[4],是森林参与全球碳循环的关键部分。因此,探究森林生态系统土壤呼吸动态变化特征对评估陆地生态系统碳循环具有重要意义。林下植被通过影响森林生态系统的地上及地下过程,在驱动森林生态系统的结构和功能方面发挥了重要作用[5−6]。研究表明:桉树Eucalyptus人工林林下植被根系呼吸占土壤总呼吸的11%~36%[7],对土壤总呼吸具有重要贡献。林下植被去除是人工林经营中一种常见的管理措施。一般而言,去除林下植被可以减少林冠与林下物种的竞争,促进种苗萌芽和生长[8−9],改变林地土壤微环境及养分有效性[10−11]。林地土壤环境的改变会引起土壤呼吸速率不同程度的升高或降低,进而影响森林生态系统土壤碳循环[12−15]。
桉树是中国南方速生丰产林的重要造林树种之一。现全球桉树人工林面积2 000多万hm2,占世界人工林面积的15%,截至2015年中国桉树人工林面积超过450万hm2,仅次于印度和巴西[16]。目前,对桉树人工林土壤呼吸的研究多集中在林型、环境因子、氮添加及林下植被去除的响应等方面[17−20],而物理去除和施用除草剂[13, 21−22]引起的土壤呼吸组分动态差异的研究少见报道。本研究以雷州半岛北部10年生尾巨桉Eucalyptus urophylla × E. grandis人工林为研究对象,分析物理和化学2种方式去除林下植被后林地土壤呼吸组分动态变化及其驱动因素,以期深入了解桉树人工林土壤碳循环过程,为经营干扰下森林土壤碳排放估算提供科学依据。
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2017年12月,选取10年生尾巨桉人工林,林分密度为667株·hm−2,郁闭度为47%,平均树高为22.66 m,平均胸径为22.70 cm。采用随机区组设计,设置物理、化学2个林下植被去除处理,以未去除为对照。每个处理各布置3块40 m×40 m重复样地,样地间隔10 m,在每个样地中心设置1个20 m × 20 m的样方。物理去除使用割灌机贴地割除灌草并作移除处理,移除前在每个20 m × 20 m样方内随机设置3个2 m × 2 m的灌草收集样方,收集林下植被地上部分,并分别称取鲜质量,测定含水量(将植被新鲜样品放置于烘箱内,在65 ℃条件下烘至恒量),换算为单位面积干质量。化学去除喷施除草剂(草甘膦铵盐水剂,草甘膦铵盐质量分数为33%,草甘膦质量分数为30%,用量为7 500 mL·hm−2),植被残体不移除。3次林下植被去除时间分别为2017年12月、2018年6月、2018年12月,每次在物理去除和对照喷施与化学去除等量的不含除草剂的水,以去除施药导致土壤水分增大带来的差异。3次物理去除处理的灌草地上部分生物量均值分别为5.94、5.70、4.56 t·hm−2。试验地处理前后土壤基本概况见表1。
表 1 试验地基本概况
Table 1. Survey of sample plots
采样时间(年-月) 处理 有机碳/(g·kg−1) 全氮/(g·kg−1) 全磷/(g·kg−1) pH 2017-12 − 33.37±0.30 a 2.50±0.06 a 0.89±0.01 a 4.48±0.02 a 2019-03 物理 30.03±0.73 b 2.09±0.08 b 0.85±0.01 ab 3.97±0.01 c 化学 32.65±0.52 a 2.54±0.06 a 0.80±0.04 b 4.12±0.01 b 对照 33.76±0.58 a 2.48±0.09 a 0.90±0.02 a 4.40±0.01 a 说明:数值均为0~20 cm土层均值±标准误。不同小写字母表示不同处理间差异显著(P<0.05);−表示林下植被去除处理之前的本底调查 -
2018年3月至2019年3月,每月月中和月底测定2次(避开阴雨天气)土壤呼吸速率,测定时间为9:00—12:00。测定采用LI-8100A土壤碳通量自动测量系统(Li-COR),系统配套的土壤温度和湿度传感器测定土壤5 cm深处的温度和湿度(体积含水率)。为降低断根呼吸的影响[23],于测定开始前3个月,在每个20 m × 20 m样方中随机设置9个1 m×1 m小区(相互间隔最小为2 m),作3类观测小区:断根去凋(切断根系+去除凋落物层)、去凋(去除凋落物层)、对照(保留根系和凋落物层)。每类小区重复3次。断根小区采用壕沟法(宽度20 cm,深度100 cm),硬质聚氯乙烯板置于沟中用以阻隔林木根系,并按原土壤层次进行回填。壕沟距离树干2~3 m,故可认为死根分解对土壤呼吸影响较小[24]。去凋小区移除现有凋落物层,上方放置塔形尼龙网筛阻止凋落物进入。每个小样方中心位置埋设1个PVC环(内径20 cm,高10 cm),垂直压入土壤5 cm深处。每次测定前剪除环内活地被物,并保证在整个观测期间对土壤环无扰动。
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土壤呼吸组分计算公式为:RM=R1;RR=R2−R1;RL=R3−R2;RA=R3。其中:RM为矿质土壤呼吸速率(μmol·m−2·s−1);RR为根系呼吸速率(μmol·m−2·s−1);RL为凋落物层呼吸速率(μmol·m−2·s−1);R1为断根去凋小区土壤呼吸速率(μmol·m−2·s−1);R2为去凋小区土壤呼吸速率(μmol·m−2·s−1);R3对照小区土壤呼吸速率,即土壤总呼吸速率RA(μmol·m−2·s−1)。
采用指数方程描述土壤呼吸及其组分与土壤温度的关系:
$ R=a{\mathrm{e}}^{bT} $ 。其中:R为土壤总呼吸速率或各组分呼吸速率(μmol·m−2·s−1);T为对应处理的土壤温度(℃,5 cm);a为温度0 ℃时的土壤呼吸速率(μmol·m−2·s−1);b为温度反应系数。采用二次函数方程描述土壤呼吸及其组分与土壤湿度的关系:
$ R={c}_{1}+{c}_{2}W+{c}_{3}{W}^{2} $ 。其中:R为土壤总呼吸速率或各组分呼吸速率(μmol·m−2·s−1);W为土壤湿度(%,5 cm),c1、c2、c3为拟合参数。采用线性模型描述土壤呼吸及其组分土壤温度、湿度的叠加效应:
$ \mathrm{l}\mathrm{n}R=\alpha +\beta T+\gamma W+\delta {T}^{2}+\varepsilon {W}^{2} $ 。其中:R为土壤总呼吸速率或各组分呼吸速率(μmol·m−2·s−1);T为对应处理的土壤温度(℃,5 cm);W为土壤湿度(%,5 cm);α、β、γ、δ、ε为拟合参数。土壤呼吸温度敏感性系数(Q10)计算公式为:
$ {Q}_{10}={\mathrm{e}}^{10b} $ 。其中:b为温度反应系数。采用重复测量方差(ANONA)检验土壤呼吸速率及其组分和土壤温度、湿度变化的差异显著性;单因素方差分析(one-way ANOVA)检验土壤呼吸速率及土壤温度、湿度年均值差异性。
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从表2可见:与对照相比,物理和化学去除分别使土壤总呼吸速率降低了33.27%和19.73%,且三者存在显著差异(P<0.05)。物理和化学去除使矿质土壤呼吸速率分别降低了35.40%和31.68%(P<0.05)。仅物理去除使根系呼吸速率降低了25.55%,化学去除对根系呼吸速率无显著影响。物理和化学去除分别使凋落物层呼吸速率降低了36.53%和23.74% (P<0.05)。矿质土壤呼吸速率、根系呼吸速率和凋落物层呼吸速率对土壤总呼吸速率的贡献率分别为26.34%~31.29%、30.10%~35.26%和36.45%~39.40%,凋落物层呼吸速率和根系呼吸速率占主要部分。与对照相比,仅化学去除显著降低了矿质土壤呼吸速率对土壤总呼吸速率的贡献率(26.34%)(P<0.05)。
表 2 土壤呼吸及其组分、土壤温湿度、土壤有机碳储量平均值多重比较
Table 2. One way ANOVA for the means of soil respiration components, soil temperature, soil moisture, and soil organic carbon storage
处理 RA/
(μmol·m−2·s−1)RM RR RL T1/℃ 数值/
(μmol·m−2·s−1)贡献率/% 数值/
(μmol·m−2·s−1)贡献率/% 数值/
(μmol·m−2·s−1)贡献率/% 物理 3.45±0.14 C 1.04±0.06 B 31.29±1.56 A 1.02±0.07 B 32.26±2.28 A 1.39±0.13 B 36.45±2.28 A 24.32±0.36 Aa 化学 4.15±0.15 B 1.11±0.06 B 26.34±1.08 B 1.37±0.11 A 35.26±2.76 A 1.67±0.13 B 38.39±2.57 A 24.94±0.39 Aa 对照 5.17±0.23 A 1.61±0.12 A 30.51±1.65 A 1.37±0.09 A 30.10±2.27 A 2.19±0.17 A 39.40±1.83 A 25.28±0.41 Aa 处理 T2/℃ T3/℃ W1/% W2/% W3/% SOCs1/
(t·hm−2)SOCs2/
(t·hm−2)SOCs3/
(t·hm−2)物理 24.56±0.36 Aa 24.00±0.32 Aa 18.00±0.75 Bc 20.86±0.83 Ab 24.03±0.94 Aa 55.93±1.19 Cb 63.02±0.76 Ba 55.18±0.47 Cb 化学 24.00±0.33 Aa 24.39±0.35 Aa 18.45±0.75 Bb 21.47±0.89 Aa 21.60±0.81 Aa 59.46±0.72 Bb 65.66±0.38 Aa 62.89±1.14 Ba 对照 24.80±0.36 Aa 24.53±0.33 Aa 22.80±0.90 Aa 20.50±0.90 Aa 22.42±0.89 Aa 63.98±0.95 Ab 61.60±0.85 Bb 69.01±0.69 Aa 说明:不同大写字母表示不同林下植被处理方式间差异显著(P<0.05),不同小写字母表示不同试验小区间差异显著(P<0.05)。RA、RM、RR、RL分别为土壤总呼吸速率、矿质土壤呼吸速率、根系呼吸速率、凋落物层呼吸速率。T1、T2、T3分别表示断根去凋小区、去凋小区、对照小区土壤温度。W1、W2、W3分别表示断根去凋小区、去凋小区、对照小区土壤湿度。SOCs1、SOCs2、SOCs3分别表示断根去凋小区、去凋小区、对照小区0~20 cm土壤有机碳储量。数值为平均值±标准误 不同处理间土壤温度无显著差异(P>0.05),说明土壤温度对林下植被和凋落物去除未产生明显变异。植被去除显著降低了断根去凋小区土壤湿度(P<0.05)。物理去除中,土壤湿度从大到小依次为对照小区(24.03%)、去凋小区(20.86%)、断根去凋小区(18.00%)。化学去除中,对照小区(21.60%)和去凋小区(21.47%)土壤湿度显著高于断根去凋小区(18.45%)(P<0.05)。
物理和化学去除林下植被显著降低了断根去凋小区和对照小区0~20 cm土壤有机碳储量(P<0.05),保留林下植被时,对照小区(保留根系和凋落物)0~20 cm土壤有机碳储量显著高于其他小区(P<0.05),说明去除林下植被和凋落物均减少了土壤碳输入。
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由图1可见:化学去除和对照处理的土壤总呼吸速率月均值在6月最大,物理去除有所推迟,在8月最大。对照样地土壤总呼吸速率月均值在2月最小,物理、化学去除均提前到12月达到最低值。物理、化学去除的矿质土壤呼吸速率及根系呼吸速率在7月骤降,凋落物层呼吸速率则在7月有较大幅度升高,升降幅度差异使得物理、化学去除的土壤总呼吸速率出现差异性变化趋势。
图 1 不同林下植被处理方式土壤呼吸及其组分月动态
Figure 1. Inter-monthly change of soil respiration and its components in different understory treatments
土壤温度、湿度月动态变化均表现出先升后降的趋势(图2)。物理去除的各小区土壤温度均在6月最高,化学去除及对照各小区均在5月最高。不同处理土壤温度最低值均出现在12月。各处理土壤湿度最高值均出现在7—8月,最低值出现在3月和翌年1—2月。
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土壤总呼吸速率、矿质土壤呼吸速率、凋落物层呼吸速率与土壤温度呈极显著正相关(P<0.01),根系呼吸速率与土壤温度无显著相关性(P>0.05)。由图3可知:不同处理土壤温度对呼吸速率变化的解释能力差异较大。物理和化学去除的土壤温度分别能解释土壤总呼吸速率变化的61.2%和54.8%,高于对照(34.7%);化学去除的土壤温度能解释矿质土壤呼吸速率变化的41.1%,高于对照(36.7%)和物理去除(12.1%);物理和化学去除的土壤温度分别能解释凋落物层呼吸速率变化的29.0%和25.4%,高于对照(10.7%)。与对照相比,林下植被去除增大了土壤总呼吸速率和凋落物层呼吸速率的温度敏感性系数,减小了矿质土壤呼吸速率温度敏感性系数。矿质土壤呼吸速率和凋落物层呼吸速率温度敏感性系数均为化学去除高于物理去除,土壤总呼吸速率温度敏感性系数为物理去除高于化学去除。
从图4可知:根系呼吸速率与土壤湿度存在显著负相关关系(P<0.05),矿质土壤呼吸速率、凋落物层呼吸速率和土壤总呼吸速率均与土壤湿度存在极显著正相关关系(P<0.01)。土壤总呼吸速率、凋落物层呼吸速率与土壤水分的拟合模型优于矿质土壤呼吸速率和根系呼吸速率。物理去除的土壤水分能解释土壤总呼吸速率变化的52.3%,高于对照(41.5%),而化学去除(27.6%)则低于对照。
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由表3可知:不同处理土壤温度与湿度的协同作用能更好地解释矿质土壤呼吸速率、根系呼吸速率、土壤总呼吸速率的变化规律,但土壤湿度对凋落物层呼吸速率变化的解释能力高于土壤温度以及土壤温湿度的协同作用。物理和化学去除降低了土壤温湿度协同作用对矿质土壤呼吸速率变化的解释能力,分别降低了29.9%和15.9%。物理和化学去除土壤温湿度协同作用对根系呼吸速率变化的影响相反,物理去除使土壤温湿度对根系呼吸速率的解释能力提高了21.9%,化学去除使土壤温湿度对根系呼吸速率的解释能力降低了8.1%。物理和化学去除提高了土壤温湿度协同作用对土壤总呼吸速率的解释能力,分别是对照的1.32和1.07倍。
表 3 土壤呼吸速率与土壤温度、湿度叠加效应模型的拟合参数
Table 3. Relation model of soil respiration against soil temperature and soil moisture
项目 物理 化学 对照 α β γ δ ε α β γ δ ε α β γ δ ε 矿质土壤呼吸 数值 2.199 −0.344 9.420 0.009 −22.165 −2.261 0.055 5.728 0.001 −10.379 −4.440 0.136 12.418 −0.001 −17.571 标准误 1.432 0.119 3.871 0.003 9.052 1.287 0.103 3.343 0.002 7.436 1.484 0.120 3.092 0.003 6.010 R2 0.318 0.458 0.617 P <0.001 <0.001 <0.001 根系呼吸 数值 −9.304 0.721 7.645 −0.015 −21.526 −0.933 0.022 6.023 0.001 −16.117 −2.291 0.152 7.296 −0.003 −21.126 标准误 2.016 0.167 4.539 0.004 9.288 4.259 0.362 7.759 0.008 15.188 3.562 0.294 6.064 0.006 12.192 R2 0.343 0.043 0.124 P <0.001 0.510 <0.05 凋落物层呼吸 数值 0.637 −0.172 −1.395 0.005 12.206 −4.334 0.315 −6.974 −0.005 19.906 2.809 −0.287 2.957 0.006 2.835 标准误 2.386 0.206 3.879 0.005 7.263 3.480 0.290 6.326 0.006 12.451 4.207 0.349 5.758 0.008 10.948 R2 0.594 0.329 0.261 P <0.001 <0.001 <0.001 土壤总呼吸 数值 −0.709 0.064 2.636 0.001 −2.196 −2.115 0.239 0.184 −0.004 1.263 0.303 0.001 4.312 0.001 −4.640 标准误 0.764 0.066 1.242 0.001 2.326 0.863 0.072 1.568 0.002 3.086 1.372 0.114 1.878 0.002 3.571 R2 0.751 0.609 0.571 P <0.001 <0.001 <0.001 说明:R2表示关系模型的拟合优度,即决定系数
Response of soil respiration to understory vegetation management in Eucalyptus urophylla × E. grandis plantation
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摘要:
目的 探究不同林下植被管理措施对雷州半岛尾巨桉Eucalyptus urophylla × E. grandis人工林土壤呼吸及其组分的影响,为准确评估桉树人工林土壤碳循环提供科学依据。 方法 以尾巨桉人工林为研究对象,实施物理和化学(施用除草剂)方式去除林下植被,并以未去除为对照。采用LI-8100A土壤碳通量自动测量系统,对土壤总呼吸及其组分速率、土壤温度和湿度(5 cm深处)进行为期1 a的连续监测。 结果 物理和化学去除林下植被极显著降低了土壤总呼吸及其组分(化学去除的根系呼吸除外)(P<0.01),且物理去除的土壤总呼吸速率(3.45 μmol·m−2·s−1)显著低于化学去除(4.15 μmol·m−2·s−1)(P<0.01)。2种方式的矿质土壤呼吸速率和凋落物层呼吸速率无显著差异(P>0.05),根系呼吸速率表现为物理去除(1.02 μmol·m−2·s−1)显著低于化学去除(1.37 μmol·m−2·s−1)(P<0.05)。凋落物层呼吸、矿质土壤呼吸、根系呼吸对土壤总呼吸的贡献率分别为36.45%~39.40%、26.34%~31.29%、30.10%~39.40%。土壤总呼吸速率及其组分最高值出现在雨季(4—10月),根系呼吸速率最低值出现在7—8月。土壤总呼吸速率与土壤温度、湿度双因子拟合模型最优,能解释土壤总呼吸速率变异的75.1%(物理去除)、60.9%(化学去除)、57.1%(对照);凋落物呼吸速率时间变异主要由土壤湿度调控;根系呼吸速率与土壤温度无显著相关性,与土壤湿度呈显著负相关(P<0.05)。土壤总呼吸的温度敏感性(Q10)从大到小依次为物理去除(2.12)、化学去除(1.95)、对照(1.93)。 结论 林下植被去除通过改变林内生物和非生物因素共同作用于土壤呼吸,且物理去除林下植被相比于化学去除能更大程度降低桉树人工林土壤总呼吸速率,降低森林土壤碳排放。图4表3参49 Abstract:Objective This study aims to investigate the impact of different understory vegetation management measures on soil respiration and its components in Eucalyptus urophylla × E. grandis plantation on Leizhou Peninsula, so as to provide a reference for accurate evaluation of soil carbon cycle in Eucalyptus plantation. Method Understory vegetation removal was conducted in 2 ways (physical removal and herbicide treatment) in E. urophylla × E. grandis plantation, and the non-removal group was used as the control. The LI-8100A automatic soil carbon flux measurement system was used to continuously monitor total soil respiration and its component rates, soil temperature and humidity (5 cm deep) for 1 year. Result Physical and chemical removal of understory vegetation significantly reduced total soil respiration and its components (except chemical removal of root respiration) (P<0.01). In addition, the total soil respiration rate of physical removal (3.45 μmol·m−2·s−1) was significantly lower than that of chemical removal (4.15 μmol·m−2·s−1) (P<0.01). There was no significant difference between the two approaches in mineral soil respiration rate and litter layer respiration rate. The root respiration rate showed physical removal (1.02 μmol·m−2·s−1) was significantly lower than that of chemical removal (1.37 μmol·m−2·s−1)(P<0.05). The contribution rates of litter layer respiration, mineral soil respiration, and root respiration to total soil respiration were 36.45%−39.40%, 26.34%−31.29%, and 30.10%−39.40%, respectively. The highest value of total soil respiration rate and its components occurred in the rainy season (April−October) and the lowest value of root respiration rate occurred in July and August. The fitting model of soil total respiration rate with soil temperature and humidity was the best, which could explain 75.1% (physical removal), 60.9% (chemical removal) and 57.1% (control) of the variation of soil total respiration rate. The temporal variation of litter respiration rate was mainly controlled by soil moisture; There was no significant correlation between root respiration rate and soil temperature, but a significant negative correlation with soil moisture (P<0.05). The temperature sensitivity (Q10) of total soil respiration was 2.12 for physical removal, 1.95 for chemical removal, and 1.93 for control. Conclusion The removal of understory vegetation affects soil respiration by changing biological and abiotic factors in the forest. Compared with chemical removal, physical removal of understory vegetation can reduce the total soil respiration rate and carbon emission of forest soil to a greater extent. [Ch, 4 fig. 3 tab. 49 ref.] -
表 1 试验地基本概况
Table 1. Survey of sample plots
采样时间(年-月) 处理 有机碳/(g·kg−1) 全氮/(g·kg−1) 全磷/(g·kg−1) pH 2017-12 − 33.37±0.30 a 2.50±0.06 a 0.89±0.01 a 4.48±0.02 a 2019-03 物理 30.03±0.73 b 2.09±0.08 b 0.85±0.01 ab 3.97±0.01 c 化学 32.65±0.52 a 2.54±0.06 a 0.80±0.04 b 4.12±0.01 b 对照 33.76±0.58 a 2.48±0.09 a 0.90±0.02 a 4.40±0.01 a 说明:数值均为0~20 cm土层均值±标准误。不同小写字母表示不同处理间差异显著(P<0.05);−表示林下植被去除处理之前的本底调查 表 2 土壤呼吸及其组分、土壤温湿度、土壤有机碳储量平均值多重比较
Table 2. One way ANOVA for the means of soil respiration components, soil temperature, soil moisture, and soil organic carbon storage
处理 RA/
(μmol·m−2·s−1)RM RR RL T1/℃ 数值/
(μmol·m−2·s−1)贡献率/% 数值/
(μmol·m−2·s−1)贡献率/% 数值/
(μmol·m−2·s−1)贡献率/% 物理 3.45±0.14 C 1.04±0.06 B 31.29±1.56 A 1.02±0.07 B 32.26±2.28 A 1.39±0.13 B 36.45±2.28 A 24.32±0.36 Aa 化学 4.15±0.15 B 1.11±0.06 B 26.34±1.08 B 1.37±0.11 A 35.26±2.76 A 1.67±0.13 B 38.39±2.57 A 24.94±0.39 Aa 对照 5.17±0.23 A 1.61±0.12 A 30.51±1.65 A 1.37±0.09 A 30.10±2.27 A 2.19±0.17 A 39.40±1.83 A 25.28±0.41 Aa 处理 T2/℃ T3/℃ W1/% W2/% W3/% SOCs1/
(t·hm−2)SOCs2/
(t·hm−2)SOCs3/
(t·hm−2)物理 24.56±0.36 Aa 24.00±0.32 Aa 18.00±0.75 Bc 20.86±0.83 Ab 24.03±0.94 Aa 55.93±1.19 Cb 63.02±0.76 Ba 55.18±0.47 Cb 化学 24.00±0.33 Aa 24.39±0.35 Aa 18.45±0.75 Bb 21.47±0.89 Aa 21.60±0.81 Aa 59.46±0.72 Bb 65.66±0.38 Aa 62.89±1.14 Ba 对照 24.80±0.36 Aa 24.53±0.33 Aa 22.80±0.90 Aa 20.50±0.90 Aa 22.42±0.89 Aa 63.98±0.95 Ab 61.60±0.85 Bb 69.01±0.69 Aa 说明:不同大写字母表示不同林下植被处理方式间差异显著(P<0.05),不同小写字母表示不同试验小区间差异显著(P<0.05)。RA、RM、RR、RL分别为土壤总呼吸速率、矿质土壤呼吸速率、根系呼吸速率、凋落物层呼吸速率。T1、T2、T3分别表示断根去凋小区、去凋小区、对照小区土壤温度。W1、W2、W3分别表示断根去凋小区、去凋小区、对照小区土壤湿度。SOCs1、SOCs2、SOCs3分别表示断根去凋小区、去凋小区、对照小区0~20 cm土壤有机碳储量。数值为平均值±标准误 表 3 土壤呼吸速率与土壤温度、湿度叠加效应模型的拟合参数
Table 3. Relation model of soil respiration against soil temperature and soil moisture
项目 物理 化学 对照 α β γ δ ε α β γ δ ε α β γ δ ε 矿质土壤呼吸 数值 2.199 −0.344 9.420 0.009 −22.165 −2.261 0.055 5.728 0.001 −10.379 −4.440 0.136 12.418 −0.001 −17.571 标准误 1.432 0.119 3.871 0.003 9.052 1.287 0.103 3.343 0.002 7.436 1.484 0.120 3.092 0.003 6.010 R2 0.318 0.458 0.617 P <0.001 <0.001 <0.001 根系呼吸 数值 −9.304 0.721 7.645 −0.015 −21.526 −0.933 0.022 6.023 0.001 −16.117 −2.291 0.152 7.296 −0.003 −21.126 标准误 2.016 0.167 4.539 0.004 9.288 4.259 0.362 7.759 0.008 15.188 3.562 0.294 6.064 0.006 12.192 R2 0.343 0.043 0.124 P <0.001 0.510 <0.05 凋落物层呼吸 数值 0.637 −0.172 −1.395 0.005 12.206 −4.334 0.315 −6.974 −0.005 19.906 2.809 −0.287 2.957 0.006 2.835 标准误 2.386 0.206 3.879 0.005 7.263 3.480 0.290 6.326 0.006 12.451 4.207 0.349 5.758 0.008 10.948 R2 0.594 0.329 0.261 P <0.001 <0.001 <0.001 土壤总呼吸 数值 −0.709 0.064 2.636 0.001 −2.196 −2.115 0.239 0.184 −0.004 1.263 0.303 0.001 4.312 0.001 −4.640 标准误 0.764 0.066 1.242 0.001 2.326 0.863 0.072 1.568 0.002 3.086 1.372 0.114 1.878 0.002 3.571 R2 0.751 0.609 0.571 P <0.001 <0.001 <0.001 说明:R2表示关系模型的拟合优度,即决定系数 -
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