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Effects of conversion of evergreen broad-leaved forest to Chinese chestnut plantation on soil organic carbon pools.

天然常绿阔叶林改造为板栗林对土壤有机碳库的影响


天然林改造为人工林后,由于植被覆盖类型和经营管理措施发生改变,从而显著影响土壤有机碳库的特征.测定浙江省临安市相邻的天然常绿阔叶林和板栗林(板栗林由常绿阔叶林改造而来,集约经营10年)表层(0~20 cm)和亚表层(20~40 cm)土壤有机碳储量和不同形态活性有机碳库,用固态核磁共振方法分析土壤有机碳的化学结构特征,研究天然常绿阔叶林改造为板栗林对土壤有机碳库的影响.结果表明: 常绿阔叶林改造为板栗林后,土壤表层有机碳储量、水溶性有机碳、热水溶性有机碳、微生物生物量碳和易氧化碳含量分别下降19.7%、34.4%、25.8%、30.4%和25.2%,土壤亚表层的各指标分别下降13.5%、38.4%、19.8%、34.1%和22.2%.土壤表层烷氧碳含量、芳香碳含量以及芳香度显著降低,而烷基碳含量、羰基碳含量以及A/O-A值均显著增加;土壤亚表层烷氧碳含量显著降低,而烷基碳含量和A/O-A值显著增加,而芳香碳含量、羰基碳含量以及芳香度无显著变化.天然常绿阔叶林改造为板栗林并长期集约经营后,土壤有机碳储量和活性有机碳库均显著下降,有机碳的化学结构发生显著变化.

Converting natural forests to plantations significantly affects the characteristics of soil organic carbon (C) pools, due to the changes of vegetation cover and management practices. In this paper, to investigate the effects of conversion from evergreen broadleaved forest (EBF) to Chinese chestnut plantation (CP) on soil organic C pool, the soils from surface (0-20 cm) and subsurface (20-40 cm) layers were sampled from the above two forests (the CP was converted from the EBF and had been intensively managed for 10 years) in Lin’an City, Zhejiang Province. The soil organic C storage, labile organic C pools, and other basic soil properties were determined. The chemical composition of soil organic C was determined by nuclear magnetic resonance (NMR) technique. Results showed that the soil organic C storage, water soluble organic C (WSOC), hot water soluble organic C (HWSOC), microbial biomass C (MBC) and readily oxidizable C (ROC) concentrations in the surface layer decreased by 19.7%, 34.4%, 25.8%, 30.4% and 25.2%, respectively, after the conversion from EBF to CP. Such values for the subsurface layers decreased by 13.5%, 38.4%, 19.8%, 34.1% and 22.2%, respectively. The Oalkyl C content, aromatic C content and aromaticity of soil organic C in the surface layer decreased significantly by the landuse conversion, while alkyl C content, carbonyl C content and alkyl C to O-alkyl C (A/O-A) ratio increased significantly. The O-alkyl C content of soil organic C in the subsurface layer decreased significantly by the landuse conversion, alkyl C content and A/OA ratio increased significantly, and aromatic C content, carbonyl C content and aromaticity of soil organic C were not changed. In conclusion, converting EBF to CP and subsequent intensive management significantly decreased the soil organic C storage and labile C pool contents and altered the chemical composition of soil organic C.


全 文 :天然常绿阔叶林改造为板栗林对
土壤有机碳库的影响
岳  天1  李永夫1,2∗  肖永恒1  李永春1,2  何  洁1  姜培坤1,2  周国模1,2  刘  娟1, 2
( 1浙江农林大学浙江省森林生态系统碳循环与固碳减排重点实验室, 浙江临安 311300; 2浙江农林大学亚热带森林培育国家
重点实验室培育基地, 浙江临安 311300)
摘  要  天然林改造为人工林后,由于植被覆盖类型和经营管理措施发生改变,从而显著影
响土壤有机碳库的特征.测定浙江省临安市相邻的天然常绿阔叶林和板栗林(板栗林由常绿
阔叶林改造而来,集约经营 10 年)表层(0 ~ 20 cm)和亚表层(20 ~ 40 cm)土壤有机碳储量和
不同形态活性有机碳库,用固态核磁共振方法分析土壤有机碳的化学结构特征,研究天然常
绿阔叶林改造为板栗林对土壤有机碳库的影响.结果表明: 常绿阔叶林改造为板栗林后,土壤
表层有机碳储量、水溶性有机碳、热水溶性有机碳、微生物生物量碳和易氧化碳含量分别下降
19.7%、34.4%、25.8%、30.4%和 25.2%,土壤亚表层的各指标分别下降 13.5%、38.4%、19.8%、
34.1%和 22.2%.土壤表层烷氧碳含量、芳香碳含量以及芳香度显著降低,而烷基碳含量、羰基
碳含量以及 A / O⁃A值均显著增加;土壤亚表层烷氧碳含量显著降低,而烷基碳含量和 A / O⁃A
值显著增加,而芳香碳含量、羰基碳含量以及芳香度无显著变化.天然常绿阔叶林改造为板栗
林并长期集约经营后,土壤有机碳储量和活性有机碳库均显著下降,有机碳的化学结构发生
显著变化.
关键词  常绿阔叶林; 板栗林; 土壤碳库; 土地利用变化
本文由国家自然科学基金项目(31170576)和浙江省自然科学基金项目(LY14C160007, LY15C160006)资助 This work was supported by the Na⁃
tional Natural Science Foundation of China (31170576) and the Natural Science Foundation of Zhejiang Province (LY14C160007, LY15C160006).
2015⁃12⁃23 Received, 2016⁃05⁃03 Accepted.
∗通讯作者 Corresponding author. E⁃mail: yongfuli@ zafu.edu.cn
Effects of conversion of evergreen broad⁃leaved forest to Chinese chestnut plantation on soil
organic carbon pools. YUE Tian1, LI Yong⁃fu1,2∗, XIAO Yong⁃heng1, LI Yong⁃chun1,2, HE
Jie1, JIANG Pei⁃kun1,2, ZHOU Guo⁃mo1,2, LIU Juan1,2 ( 1 Zhejiang Province Key Laboratory of
Carbon Cycling in Forest Ecosystems and Carbon Sequestration, Zhejiang A&F University, Lin’ an
311300, Zhejiang, China; 2Nurturing Station for the State Key Laboratory of Subtropical Silvicul⁃
ture, Zhejiang A&F University, Lin’an 311300, Zhejiang, China) .
Abstract: Converting natural forests to plantations significantly affects the characteristics of soil or⁃
ganic carbon (C) pools, due to the changes of vegetation cover and management practices. In this
paper, to investigate the effects of conversion from evergreen broad⁃leaved forest (EBF) to Chinese
chestnut plantation (CP) on soil organic C pool, the soils from surface (0-20 cm) and subsurface
(20-40 cm) layers were sampled from the above two forests (the CP was converted from the EBF
and had been intensively managed for 10 years) in Lin’an City, Zhejiang Province. The soil orga⁃
nic C storage, labile organic C pools, and other basic soil properties were determined. The chemical
composition of soil organic C was determined by nuclear magnetic resonance (NMR) technique. Re⁃
sults showed that the soil organic C storage, water soluble organic C (WSOC), hot water soluble
organic C (HWSOC), microbial biomass C (MBC) and readily oxidizable C (ROC) concentra⁃
tions in the surface layer decreased by 19.7%, 34.4%, 25.8%, 30.4% and 25.2%, respectively,
after the conversion from EBF to CP. Such values for the subsurface layers decreased by 13.5%,
38.4%, 19.8%, 34.1% and 22.2%, respectively. The O⁃alkyl C content, aromatic C content and
aromaticity of soil organic C in the surface layer decreased signi⁃ficantly by the land⁃use conversion,
while alkyl C content, carbonyl C content and alkyl C to O⁃alkyl C (A / O⁃A) ratio increased signi⁃
ficantly. The O⁃alkyl C content of soil organic C in the subsurface layer decreased significantly by
应 用 生 态 学 报  2016年 7月  第 27卷  第 7期                                            http: / / www.cjae.net
Chinese Journal of Applied Ecology, Jul. 2016, 27(7): 2181-2188                  DOI: 10.13287 / j.1001-9332.201607.035
the land⁃use conversion, alkyl C content and A / O⁃A ratio increased significantly, and aromatic C
content, carbonyl C content and aromaticity of soil organic C were not changed. In conclusion,
conve⁃rting EBF to CP and subsequent intensive management significantly decreased the soil organic
C sto⁃rage and labile C pool contents and altered the chemical composition of soil organic C.
Key words: evergreen broad⁃leaved forest; Chinese chestnut plantation; soil carbon pool; land⁃use
change.
    气候变暖是人类当前面临的最严峻的全球性生
态环境问题,而 CO2和 CH4等温室气体浓度的上升
与全球气候变暖有着密不可分的关系[1] .土壤作为
陆地生态系统最大的碳库,其碳库的动态变化与大
气 CO2浓度的动态变化有着非常紧密的联系[2
-3] .土
地利用方式的改变,会引起植被覆盖类型和经营管
理措施发生改变,从而对土壤碳储量与温室气体排
放产生显著影响[4-6] .周程爱等[7]研究表明,天然林
转变为人工林后,土壤呼吸速率随着土壤有机碳含
量下降而下降. Pötzelsberger 等[8]研究表明,天然挪
威云杉林(Picea abies)转变为人工林显著影响土壤
矿化态碳含量与有机质矿化作用.另外,土壤碳库的
变化也与土壤水污染、水土流失、水富营养化等问题
有着直接或间接的联系[9-11] .因此,研究土地利用变
化对土壤有机碳库的影响机理可以为决策者解决全
球气候变暖、环境污染等生态问题提供基础资料.
土壤碳库储量巨大,又相对稳定,在短期内变化
幅度较小.因此,研究土地利用变化对土壤总有机碳
库的影响意义不大[12-13] .近年来,越来越多的学者
利用活性碳库指标,如水溶性有机碳(WSOC) [14]、
热水溶性有机碳 (HWSOC) [15]、微生物生物量碳
(MBC) [16]和易氧化碳(ROC) [17]等来表征土壤有机
碳库的变化.尽管上述活性碳库只占土壤总有机碳
库的一小部分,但因为其直接或间接地参与了养分
循环、物质转化等重要的生态过程[18-19],可以在短
期内迅速有效地反映土壤碳库中组分的转化和变
化[20-21] .因此,利用活性有机碳库指标研究土地利
用变化对土壤碳库的影响,对阐明土地利用变化对
土壤有机碳库的影响机制具有重要意义.
板栗(Castanea mollissima)是我国的主要经济
作物之一,其具有药用价值和经济价值高等特点.因
此,近年来,其种植面积日趋增加.目前,我国的板栗
种植面积已达 125×104 hm2,占世界板栗种植面积的
38%,已成为部分地区农民收入的主要来源[22] .天然
常绿阔叶林生态系统生物资源多,土壤肥沃、有机质
含量丰富,可以给板栗林的生长提供较好的土壤肥
力供给[23] .因此,为了追求较高的经济效益,营林者
将天然常绿阔叶林改造为板栗林,并采取施肥、翻耕
以及去除林下杂草等经营措施来提高板栗林产量.
但研究发现,常绿阔叶林改造为板栗林后会产生水
土流失增加、土壤温室气体排放增加以及土壤微生
物活性下降等问题[24] .土壤有机碳数量与质量是影
响土壤肥力的重要因素.天然阔叶林改造为板栗林
后,对土壤有机碳储量、活性有机碳库以及有机碳的
化学结构特征影响,目前尚未见报道.本研究选取相
邻的天然常绿阔叶林和板栗林样地(由常绿阔叶林
改造而来,集约经营 10 年),对土壤基本理化性质、
有机碳含量以及活性有机碳库含量进行分析,采用固
态核磁共振波谱技术测定土壤有机碳的化学结构特
征,研究天然常绿阔叶林改造为板栗林对土壤有机碳
库的影响,为深入研究土壤碳库对土地利用变化的响
应机制和板栗林的可持续经营提供基础资料.
1  研究地区与研究方法
1􀆰 1  研究区概况
试验地位于浙江省临安市三口镇(30°14′ N,
119°42′ E),处于临安和富阳的交界地.试验区属于
中亚热带季风气候,温暖湿润,四季分明,雨量充沛
(年降水量为 1556 mm),平均气温 15.5 ℃ .具有春
多雨、夏湿热、秋气爽、冬干冷的气候特征.试验样地
原为天然常绿阔叶林,其主要优势树种为青冈(Cy⁃
clobalanopsis glauca)、甜槠(Castanopsis eyrei)、苦槠
(Castanopsis sclerophylla)等,林龄约 25年,平均胸径
为 13.9 cm,郁闭度为 70%.林下灌木主要有山苍子
(Litsea cubeba)、山胡椒( Lindera glauca)和连蕊茶
(Camellia cuspidate)等.营林者为提高经济收益,将
部分天然常绿阔叶林改造为板栗林,并集约经营管
理 10 年.每年 5 月中下旬进行施肥,施肥量为尿素
(188 kg·hm-2)、过磷酸钙(488 kg·hm-2)和氯化
钾(135 kg·hm-2),施肥后翻耕,深度为 0.3 m 左
右,林下留有少量灌木与杂草.
1􀆰 2  试验设计
在研究区内选择 4 个配对小区(立地条件基本
一致),相邻的常绿阔叶林和板栗林形成一个配对
2812 应  用  生  态  学  报                                      27卷
小区,共 8 个样地,样地面积为 20 m×20 m.在每块
样地中,按照五点随机取样法分别采集 0 ~ 20 和
20~40 cm土层土壤进行混合,作为一个样品,共 4
个重复.土壤样品采集后,放置在有封口的塑料袋
里.带回实验室后,过筛(2 mm)去除可见根系后,分
成两部分.一部分土壤样品风干处理后保存,另一份
保存于冰箱(4 ℃)备用.
1􀆰 3  测定项目与方法
1􀆰 3􀆰 1土壤基本理化性质的测定  测定土壤 pH值、
容重、含水量、有机质、全氮、速效钾、有效磷等指标.
土壤容重采用环刀法测定;土壤 pH 值采用蒸馏水
(土水比为 1 ∶ 2.5)浸提,用 pH计测定;土壤含水量
将土样在 105 ℃中烘干计算得出;土壤有机质采用
重铬 酸 钾⁃浓 硫 酸 消 煮 法, 即 重 铬 酸 钾 (0.8
mol·L-1)和浓硫酸在 170 ~ 180 ℃煮沸 5 min 后用
硫酸亚铁滴定;全氮采用半微量凯氏定氮法测定;土
壤速效钾采用中性乙酸铵浸提法火焰光度计测定;
土壤有效磷采用 HCl⁃NH4F浸提法测定[23] .
1􀆰 3􀆰 2土壤活性有机碳库的测定  土壤 WSOC 含量
的测定参考 Jones等[25]的方法进行.土壤 HWSOC含
量的测定参考 Sparling等[26]的方法.土壤 MBC 含量
采用氯仿熏蒸直接提取法测定[27] .土壤 ROC 含量
的测定采用 Graeme等[28]的方法.
1􀆰 3􀆰 3土壤有机碳化学结构特征的测定  采用核磁
共振技术,固态13C 核磁共振波谱仪在分析土壤样
品有机碳含量和结构的过程中,会受到土壤中磁性
物质(如 Fe3+、Mn2+等离子)的干扰影响.因此,在本
研究中,土壤样品在进行核磁共振分析之前,使用氢
氟酸溶液进行预处理,消除干扰离子的影响,提高核
磁共振分析的信噪比.氢氟酸溶液预处理的方法参
考 Mathers 等[29]的方法进行.根据以往有关土壤有
机碳13C核磁共振分析试验的结果[29-31],各类含碳
基团所对应的13C信号化学位移如下:烷基碳(0~42
ppm)、烷氧碳 ( 42 ~ 110 ppm)、芳香碳 ( 110 ~ 160
ppm)和羰基碳(160 ~ 220 ppm).最后对核磁共振图
谱谱峰曲线进行区域积分,得到土壤样品中各种含
碳组分含量占总有机碳的百分比.另外,计算了 2 个
与土壤有机质稳定性关系密切的指标:芳香度:
C110⁃160 ppm / C0⁃160 ppm[30];A / O⁃A:C0⁃42 ppm /
C42⁃110 ppm[31] .
1􀆰 4  数据处理
采用 Excel 2010 和 SPSS 13.0 软件对数据进行
统计分析,采用单因素方差分析(one⁃way ANOVA)
和最小显著差数(LSD)法进行显著性分析和多重比
较(α= 0.05).利用 Origin 8.0 软件进行做图.图表中
数据为平均值±标准差.
2  结果与分析
2􀆰 1  常绿阔叶林改造为板栗林对土壤基本理化性
质的影响
从图 1 可见,天然常绿阔叶林的表层(0 ~ 20
cm)土壤pH显著高于亚表层(20 ~ 40 cm) .天然常
图 1  常绿阔叶林改造为板栗林对土壤基本理化性质的影响
Fig.1  Effects of conversion of evergreen broad⁃leaved forest to Chinese chestnut plantation on soil physical and chemical properties.
Ⅰ: 常绿阔叶林 Evergreen broad⁃leafed forest; Ⅱ: 板栗林 Chinese chestnut plantation. 不同字母表示差异显著(P<0.05) Different letters meant sig⁃
nificant difference at 0.05 level. 下同 The same below.
38127期                        岳  天等: 天然常绿阔叶林改造为板栗林对土壤有机碳库的影响         
绿阔叶林改造为板栗林后,土壤表层和亚表层的 pH
值显著降低,酸性增强;且土壤表层和亚表层的有机
碳含量在上述土地利用方式发生后,均显著下降;而
板栗林表层土壤的全氮含量显著高于常绿阔叶林土
壤,两者亚表层土壤的全氮含量无显著差异;另外,
土地利用方式发生改变后,土壤表层和亚表层的速
效钾和有效磷含量均显著上升,变化程度均为土壤
表层高于亚土层.
2􀆰 2  常绿阔叶林改造为板栗林对土壤有机碳储量
的影响
由图 2 可见,常绿阔叶林和板栗林的土壤表层
碳储量均显著高于亚表层.常绿阔叶林改造为板栗
林后,土壤表层和亚表层中有机碳储量分别下降了
19.7%和 13.5%;从 0~40 cm土层来看,常绿阔叶林
图 2  常绿阔叶林改造为板栗林对土壤有机碳储量的影响
Fig.2  Effects of conversion of evergreen broad⁃leaved forest to
Chinese chestnut plantation on the SOC storage.
改造为板栗林后,土壤碳储量下降了 16.9%.
2􀆰 3  常绿阔叶林改造为板栗林对土壤活性有机碳
含量的影响
由图 3可以看出,常绿阔叶林改造为板栗林后,
土壤表层水溶性有机碳(WSOC)、热水溶性有机碳
(HWSOC)、微生物量碳(MBC)和易氧化碳(ROC)
含量分别下降了 34.4%、25.8%、30.4%和 25.2%.土
壤亚表层水溶性有机碳、热水溶性有机碳、微生物生
物量碳和易氧化碳含量分别下降了 38.4%、19.8%、
34.1%和 22.2%.这表明天然常绿阔叶林改造为板栗
林后,土壤表层和亚表层的活性碳库均存在一定程
度的耗竭.
2􀆰 4  常绿阔叶林改造为板栗林对土壤有机碳化学
结构的影响
由图 4 可以看出,常绿阔叶林和板栗林土壤均
包含 4个明显的共振区:烷基碳区、烷氧碳区、芳香
碳区和羰基碳区.从表 1可见,无论是常绿阔叶林还
是板栗林,有机碳的最大组分均为烷氧碳,其次为烷
基碳.常绿阔叶林改造为板栗林后,土壤表层和亚表
层的不同碳形态(烷基碳、烷氧碳、芳香碳和羰基
碳)含量显著变化.其中,土壤表层有机碳的烷氧碳
含量、芳香碳含量以及芳香度均显著降低,而烷基碳
含量和 A / O⁃A值均显著增加;土壤亚表层烷氧碳含
量显著降低,烷基碳含量和 A / O⁃A 值显著上升,而
芳香碳含量、羰基碳含量以及芳香度无显著变化.
图 3  常绿阔叶林改造为板栗林对土壤不同活性有机碳库的影响
Fig.3  Effects of conversion of evergreen broad⁃leaved forest to Chinese chestnut plantation on different labile organic C pools in the
soil.
4812 应  用  生  态  学  报                                      27卷
表 1  常绿阔叶林改造为板栗林对不同土层土壤不同含碳组分百分比的影响
Table 1  Effects of conversion of evergreen broad⁃leaved forest to Chinese chestnut plantation on the percentage of diffe⁃rent
C fractions in the soil
土层
Soil layer
(cm)
森林类型
Forest type
烷基碳
Alkyl C
烷氧碳
O⁃alkyl C
芳香碳
Aromatic C
羰基碳
Carbonyl C
A / O⁃A 芳香度
Aromaticity
0~20 常绿阔叶林 Evergreen broad⁃leaved forest 23.8±1.8b 48.6±1.6a 16.6±1.3a 11.0±0.7b 0.49±0.04a 18.6±1.1a
板栗林 Chinese chestnut plantation 32.5±2.1a 41.8±1.7b 12.9±0.9b 12.8±1.2a 0.78±0.07b 14.8±0.8b
20~40 常绿阔叶林 Evergreen broad⁃leaved forest 23.5±1.7b 46.2±2.1a 18.3±1.4a 12.0±0.7a 0.51±0.05a 20.8±1.2a
板栗林 Chinese chestnut plantation 31.2±2.7a 39.5±1.7b 16.3±1.1a 13.0±0.8a 0.79±0.09b 18.7±1.0a
同列不同字母表示差异显著(P<0.05) Different letters in the same column meant significant difference at 0.05 level.
图 4  常绿阔叶林和板栗林土壤有机碳固态13C⁃核磁共振
波谱
Fig.4  Solid⁃state 13C NMR spectra for soil organic carbon in
evergreen broad⁃leaved forest and Chinese chestnut plantation.
3  讨    论
在本研究中,天然常绿阔叶林改造为板栗林后,
土壤表层和亚表层的碳储量含量分别下降 19.7%和
13.5%,这与国内外有关天然林改造为人工林对土
壤碳储量的研究结果一致.如 Kasel等[32]报道,天然
林改造为松树人工林后,土壤表层有机碳储量下降
30%;Fern􀅡ndez⁃Romero等[33]研究表明,天然林改造
为橄榄人工林后,土壤表层碳储量下降 40%;
Demessie等[34]报道,天然林改造为赤桉(Eucalyptus
camaldulensis)、蓝桉 (Eucalyptus globulus)、柳叶桉
(Eucalyptus saligna)、松树(Pinus patula)、刺柏(Ju⁃
niperus formosana)和柏木(Cupressus funebris)6 种人
工林后,土壤表层有机碳储量下降 59.1% ~ 94.5%.
本研究中,天然常绿阔叶林改造为板栗林导致土壤
有机碳储量下降的原因可能是:1)与天然常绿阔叶
林相比,板栗林的集约经营措施(翻耕和去除林下
杂草)会导致土壤的水土涵养功能变差,从而更容
易发生可溶性养分(包括可溶性有机碳)的流失;2)
板栗林经营过程中采用施用化肥和翻耕等措施会促
进土壤有机质的分解[35] .天然林改造为人工林引起
土壤有机质水平的下降可能会影响人工林的可持续
经营.因此,在今后人工林的管理措施方面,应该采
用免耕、保留林下植被以及使用有机肥等方式,来提
升人工林土壤的有机碳储量.然而,Mujuru 等[36]报
道,天然林改造为松树人工林并集约经营 10 年后,
土壤有机碳储量存在回升的现象,这可能是由于不
同人工林的养分归还特征与经营措施等存在差异.
目前,很多研究表明,土地利用变化显著影响土
壤活性碳库 (水溶性有机碳、微生物生物量碳
等) [7,37] .在本研究中,天然阔叶林改造为板栗林后,
土壤表层和亚土层的 WSOC 显著下降,这与吴秀坤
等[38]的研究结果一致.本研究中,土地利用变化引
起土壤 WSOC下降的原因可能是:1)林下植被死亡
残余物是土壤 WSOC 的来源之一,而板栗林在经营
管理过程中进行林下植被去除处理.另外,板栗人工
林的水土涵养较差,也导致一部分 WSOC 通过水土
流失而损失掉;2)板栗林经营管理措施中的施肥与
翻耕会导致土壤中部分活性有机碳组分转化为难降
解的碳组分或 CO2 而损失;3)集约经营板栗林生长
速度较快,加快了植株对土壤有机营养物质的吸收,
在一定程度上引起 WSOC的下降.但肖鹏等[39]研究
表明,天然常绿阔叶林改造为雷竹 ( Phyllostachys
praecox)林后,土壤表层和亚土层中的 WSOC 含量
显著增加.这可能是因为雷竹林的集约经营措施包
括有机物料的覆盖,而有机覆盖物降解会释放大量
的水溶性有机碳化合物,从而显著增加土壤 WSOC
含量[40-41] .另外,本研究还发现,天然阔叶林改造为
板栗林后,土壤表层和亚表层的 MBC含量均显著下
58127期                        岳  天等: 天然常绿阔叶林改造为板栗林对土壤有机碳库的影响         
降,其原因可能是:长期施肥会导致板栗林土壤微生
物活性下降[42-44];板栗林土壤 pH 显著低于天然常
绿阔叶林土壤(图 1),pH值的下降会抑制土壤微生
物的生长和繁殖[45-46],从而导致土壤 MBC 含量下
降.ROC 的变化机理与 WSOC 的变化机理基本相
似,主要也是板栗林的各种经营措施所致.此外,常
绿阔叶林改造为板栗林对土壤各活性碳库的影响程
度在表层与亚表层之间存在显著差异,其原因可能
是:与亚表层相比,表层土壤的活性碳库更容易受到
经营管理措施(如施肥、翻耕等)的影响;林木的根
系较长,其根际范围也较大.林木根系生长(细根代
谢或根系分泌物)对亚表层土壤活性碳库的影响,
可能高于表层土壤[47-48] .
固态13C核磁共振波谱分析技术在鉴定土壤有
机碳结构信息方面具有独特的优势,因此,该技术已
经被越来越多的研究人员采用[49-51] .本研究中,常
绿阔叶林和板栗林土壤中的有机碳组分均以烷氧碳
组分最多.这与 Mathers 等[52]在松树林土壤中的研
究结果一致.Zhang等[53]研究也表明,水稻田和集约
经营雷竹林土壤有机碳的组分也是以烷氧碳组分最
多.然而,也有一些研究与本试验结果存在显著差
异.如 Chen 等[54]通过核磁共振技术研究了杉木林
土壤的有机碳化学结构特征,发现杉木林有机碳中
的最大碳组分是烷基碳.不同研究结果之间的差异
可能是由于植物种类、管理措施、土壤类型以及研究
地气候环境等因素存在差异[53] .本研究表明,天然
常绿阔叶林改造为板栗林后,土壤的烷氧碳比例下
降,而烷基碳的比例上升.这可能是因为,板栗林采
用的集约经营措施(如施肥翻耕等)会导致土壤中
活性有机碳库分解(土壤活性碳库的化学结构主要
以烷氧碳为主),从而导致土壤烷氧碳含量下降.此
外,本研究还发现,天然常绿阔叶林改造为板栗林显
著降低土壤的芳香碳比例和芳香度.这可能是因为,
在集约经营的条件下,板栗林土壤很难形成新的芳
香碳化合物,相反原本存在于土壤中的一部分芳香
碳化合物会因集约经营措施的作用而被分解[55] .
4  结    论
天然常绿阔叶林改造为板栗林后,表层和亚表
层土壤有机碳储量显著下降,活性有机碳库指标
(WSOC、HWSOC、MBC 和 ROC)均显著降低;土壤
有机碳的固态13C 核磁共振波谱表明,天然常绿阔
叶林改造为板栗林后,表层和亚表层土壤有机碳中
烷氧碳含量、芳香碳含量以及芳香度均显著下降,而
烷基碳含量和 A / O⁃A 值显著上升.因此,上述土地
利用变化对土壤有机碳库(碳储量和活性碳库)主
要起负面效应.为了促进板栗人工林的可持续经营,
建议在营林过程中采用保留或添加林下植被、施加
有机肥和生物质炭等措施来提升土壤有机质水平.
此外,由于本试验只是比较了天然常绿阔叶林和集
约经营 10年的板栗林在土壤碳库特征上的差异,而
集约经营的时间和林龄也会对土壤碳库特征产生显
著影响.因此,今后要对不同集约经营时间板栗林土
壤的碳库变化特征进行研究,以明确天然林改造为
人工林影响土壤碳库特征的短期效应与长期效应.
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作者简介  岳  天,女,1990年生,硕士研究生. 主要从事森
林生态系统碳循环与固碳减排研究. E⁃mail: yuetianzafu@
163.com
责任编辑  孙  菊
岳天, 李永夫, 肖永恒, 等. 天然常绿阔叶林改造为板栗林对土壤有机碳库的影响. 应用生态学报, 2016, 27(7): 2181-2188
Yue T, Li Y⁃F, Xiao Y⁃H, et al. Effects of conversion of evergreen broad⁃leaved forest to Chinese chestnut plantation on soil organic
carbon pools. Chinese Journal of Applied Ecology, 2016, 27(7): 2181-2188 (in Chinese)
8812 应  用  生  态  学  报                                      27卷