全 文 ：Journal of Forestry Research, 13 (1): 33-36 (2002) 33
Composition and properties of soil humus in a mixed forest of
Cunninghamia lanceolata and Tsoongiodendron odorum
YANG Yu-sheng, GUO Jian-fen, LIU Yan-li, LIN Rui-yu, CHEN Guang-shui
(Fujian Agricultural and Forestry University, Nanping 353001, P. R. China)
Abstract: This study was conducted in Xinkou Experimental Forestry Farm of Fujian Agricultural and Forestry University,
Sanming, Fujian Province in January 1999. Taking pure stand of Chinese fir as control, the authors measured and studied the
content of organic carbon, content of humic acid (HA), ratio of HA to fulvic acid (FA), and the characteristics of infrared light
spectrum and visible light spectrum of soil humus in the mixed forest of Chinese fir and Tsoong’ tree. Compared to humus
composition in the pure stand of Chinese fir, the content of soil organic C, HA content, and the E4 value of HA for different layers
of soil, except for the ratio of HA to FA, showed a significant increase in the mixed forest, while the ratios of E4 to E6 had a little
decrease. The infrared light spectrum of humic acid had an absorptive peak at 1650 cm-1. It is concluded that the levels of
humification and aromaticity of soil humus are higher in the mixed forest, which is favorable for the improvement of soil structure
and nutrient supply, thus improving the soil fertility to a certain degree.
Keywords: Chinese fir; Tsoong’s tree; Mixed forest; Soil humus fraction; Optical properties
CLC number: S714.5; S791.27.02 Document code: A Article ID: 1007-662X(2002)01-0033-04
Introduction1
Chinese fir (Cunninghamia lamcealata (Lamb.) Hook) is
one of the most important plantation tree species in China
in terms of planting area, yield and timber usage. The
continuous monoculture of Chinese fir is a traditional
silvicultural practice. However, yield decline and soil
degradation have widely occurred in Chinese fir stands
with such a forestry practice. This problem has caused
considerable attentions.
In order to preserve long-term site productivity or to
restore soil fertility in a degraded site, mixing broad-
leaveds in a stand have been tried as silvicultural
measures (Yang 1998; Yu 1996; Zheng et al. 1998). Some
characteristics of soil feritlity have been reported in the
mixed stands of Chinese fir and several broad-leaveds (Yu
1996; Yang et al. 1996). However, study on composition
and propertie of soil humus in these forests was limited.
Soil humus was involved in many of the soil chemical,
physical and biological processes determining the capacity
of a soil to support plant growth, and, an assessment of
humus properties is critical to define overall soil quality.
Although there was great interest in the role of humus in
soil nutrition and ecosystem function, there have been few
studies providing unequivocal identification and
Foundation item： This paper was supported by Natural Science
Foundation of Fujian Province (B0110025) and Foundation for
University Key Teacher by the Ministry of Education.
Biography： YANG Yu-sheng (1964-), male, professor in Fujian
Agricultural and Forestry University, Nanping 353001, P. R. China.
Received date: 2001-12-12
Responsible editor: Zhu Hong
quantification of humus because of the heterogeneous and
polydisperse nature of humic substances, and the
complexity of the inter- and intramolecular reactions. In this
study, we focused attention on the organic C, humic and
fulvic acid, and optical properties of humus to compare the
difference of humic substances extracted from soils in a
mixed forest of Chinese fir with Tsoong’ tree
(Tsoongiodendron odorum Chun) and an adjacent pure
Chinese fir forest.
Sites
The study was conducted in Xiaohu experimental area
of Xinkou Experimental Forestry Farm of Fujian
Agricultural and Forestry University, Sanming, Fujian
Province (26°11¢30² N, 117°26¢00² E). The sites are on the
slope of 35° in facing northeast in the mixed forest of
Chinese fir and Tsoong’ tree, and in the pure Chinese fir
stand, respectively. The climate is characterized by sub-
tropical monsoon, with an annual mean temperature of
19.1 °C, an annual mean precipitation of 1 749 mm, an
annual mean evaporation of 1 585 mm, an annual mean
relative humidity of 81%, and a frost-free period of 300 d.
The soil is red soil derived from sandy shale.
The mixed forest and pure stand were established with
seedling in 1973, with an initial planting density of 3 000
stems per hectare. The mixed pattern is strip spacing,
three rows of Chinese fir spaced by one row of Tsoong’
tree. At the time of survey, the pure stand (at age of 27)
had a density of 1 100 stems per hectare, with a crown
density of 0.80 and undergrowth coverage of 95%. The
mean tree height and diameter at breast height were 19.61
m and 23.6 cm respectively. In the surface soil (0-20 cm),
the contents of hydrolysable N, available P, and available
YANG Yu-sheng et al. 34
K were 86.21 mg·kg -1, 4.92 mg·kg-1 and 82.31 mg·kg -1,
respectively. The mixed stand had a density of 907 stems
per hectare for Chinese fir and 450 stems per hectare for
Tsoong’ tree. The mean tree height and DBH were 20.88
m and 25.1 cm for Chinese fir, 17.81 m and 17.0 cm for
Tsoong’ tree, respectively. The crown density was of 0.95
and the undergrowth coverage was of 80%. The contents
of hydrolysable N, available P, and available K in the
topsoil at 0-20 cm, were 106.80 mg·kg -1, 5.42 mg·kg -1 and
92.65 mg·kg-1, respectively.
Materials and methods
Soil collection
Six plots (20 m × 20 m) were established in each stand.
For determination of soil humus, soil samples were
collected in January 1999 from five sampling locations
following a sigmoid route across each plot. Soil was
divided into three layers, 0-20 cm, 20-40 cm and 40-60 cm.
Soil samples at the same layer in each plot were equally
mixed.
Soil analysis
Soil organic C content was determined by the procedure
of heating oxidation with the mixture of K2Cr2O7 and H2SO4
at (180±5) °C for five minutes. For determination of soil
humus fractionation, each sample was extracted with the
mixture of 0.1 mol/L NaOH and 0.1 mol L-1 Na4P2O7 in a
airtight container, which was made of polyethylene and
filled with nitrogen, at (20±1) °C for 16 h, then the
suspension was filtrated the next day. 10-25-mL alkaline
extract was subsampled from the filtrate and added with 6
mol/L HCl to pH 1.5, vaporized; then humus C content was
determined with the oxidizing method. Another 10-50-mL
alkaline extract was subsampled, added with 6 mol/L HCl
to pH 3, heated at (80±1) °C for half an hour, cooled, and
then centrifuged the next day. HA precipitate was obtained
and dissolved in 0.05 mol/L NaOH. 10-25-mL subsample
dissolved in 0.05 mol/L NaOH was made to determine
humic acid C content. C content of all samples was also
determined as the method described above. In addition, in
order to purified humic acids, the raw humic acids were
treated with 0.5%HF: 0.5%HCl (removal of SiO2) and
dissolved in 0.05 mol/L NaOH, dialysed until no Cl- can be
examined by 1% AgNO3 solution, then dialysed with a self-
made electric dialysed equipment to pH (6.5-7.0) and
freeze-dried (Kononoba 1966). The values of E4 and E6
were determined by dissolving HA in 0.05 mol/L NaHCO3
and measuring optical densities at 465 nm and 665 nm
with an UV-120-02 ultraviolet–visible spectrometer (Chen
et al. 1977). FT-IR spectra were obtained from KBr-pellets
of freeze-dried samples on a Perkin-Elmer-Spectrum-2000
FTIR spectrophotometer (Takacs et al. 1999).
Statistical analysis
Significant differences in various parameters of soil
humus (e.g. soil organic C, humic C, percentage HA and
FA) at each soil layer between the mixed and pure stands
were determined by Students t-tests, which was at a
significant level of 0.05.
Results
Soil humus composition
The contents of organic C and humus C in the topsoil of
the mixed forest were 19% and 36% higher than those of
the pure stand, respectively. The degree of humification,
an index of soil humus property referred to the proportion
of soil humic acid (HA) in total soil C, was 1.25 times, and
the content of humic acid was 1.49 times, as much as
those of the pure stand, respectively. In addition, HA/FA
ratio in the surface soil of the mixed forest was higher than
that of the pure stand, although this difference was not
statistically significant (Table 1). The same trends occurred
in soil depths of 20-40cm and 40-60 cm.
Table 1. Composition and optical property of soil humus (mean±SE, n=6)
Stands type Soil layer /cm OM-C /g·kg-1 Humus-C /g·kg-1 HA-C /g·kg-1 FA-C /g·kg-1
0-20 15.68±0.47* 8.60±0.28* 2.47±0.20* 6.13±0.18*
20-40 8.70±0.45* 5.65±0.29* 0.90±0.06* 4.75±0.09*
Mixed forest
40-60 6.37±0.24 * 3.67±0.51 0.52±0.05* 3.15±0.15
0-20 13.18±0.39 6.33±0.24 1.66±0.18 4.67±0.22
20-40 5.84±0.42 3.58±0.38 0.44±0.06 3.14±0.27
Pure forest
40-60 4.70±0.27 2.75±0.47 0.22±0.03 2.53±0.12
Stands type Soil layer /cm HA (%) FA (%) HA/ FA E4 E4/E6
0-20 15.75±0.05* 39.09±0.09* 0.40 0.36±0.03* 5.26
20-40 10.34±0.07* 54.60±0.10* 0.19 0.30±0.02* 6.12
Mixed forest
40-60 8.16±0.03* 49.45±0.08 0.17 0.21±0.01* 6.50
0-20 12.59±0.09 35.43±0.11 0.36 0.27±0.02 5.41
20-40 7.53±0.05 53.77±0.09 0.14 0.14±0.01 6.36
Pure forest
40-60 4.68±0.07 53.83±0.06 0.09 0.11±0.01 6.71
Notes: OM-C, HA-C, and FA-C stand for carbon content of organic matter, humic acid, and fulvic acid respectively. HA-humic acid, FA stand for
fulvic acid. HA%=HA-C/MO-C×100, FA%= FA-C/MO-C×100. HA/FA is ratio of carbon content of humic acid to fulvic acid. E4 and E6 are extinct
coefficient of HA at 465 nm and 665 nm, respectively. Significant differences (p<0.05) in the same soil layer between the mixed and pure forests are
indicated with an asterisk.
Journal of Forestry Research, 13 (1): 33-36 (2002) 35
4 0 0 0 3 0 0 0 2 0 0 0 1 5 0 0 1 0 0 0 5 0 0 3 7 0
T
ra
n
s
m
is
s
iv
it
y
(
%
)
W a v e - n u m b e r ( c m
- 1
)
M i x e d f o r e s t
4 0 - 6 0 c m
M i x e d f o r e s t
2 0 - 4 0 c m
M i x e d f o r e s t
0 - 2 0 c m
P u r e f o r e s t
4 0 -6 0 c m
P u r e f o r e s t
2 0 - 4 0 c m
P u r e f o r e s t
0 - 2 0 c m
Optical properties of soil humus
The E4 value (the optical density at 465 nm wavelength)
of humic acid in the surface soil of the mixed forest was
33% higher than that of the pure stand, while lower E4/E6
ratio of soil HA was observed in the mixed forest (Table 1).
The FT-IR spectra of soil humic acids showed structural
difference of HAs from the two stands (Fig. 1). The spectra
showed the following absorbances: broad-leaved band in
the 3 350-3 450 cm-1 region, due to H-bonded OH stretch;
sharp peaks at 2 920 cm-1, attributed to aliphatic C-H
stretch; broad-leaved bands at 1 640-1 665 cm-1, originated
from quinone C=O and aromatic C=C stretch; bands at
1 380-1 390 cm-1, produced by COO- groups and/or
aliphatic C-H stretch; absorption bands around 1 240 cm-1;
produced by C-O stretch and/or O-H deformation
vibrations of carboxyl groups, sharp peaks around 1 050
cm-1 due to silicates and/or polysaccharides; The
absorption bands at 465 cm-1 are probably due to the
present of silicate. Most infrared spectra of soil HAs in the
mixed forest were coincident with those in the pure stand
(Fig.1), it is suggested that their HAs had similar molecular
structure and functional groups (Liu 1990). However, the
former having characteristic absorption peak around 1 720
cm-1 was representative of its undissociated COOH and
COOR groups, absorption bands at 1 650 cm-1 also
indicated higher degree of polycondensation.
Fig. 1 Infrared absorption spectra of soil HA at three soil
layers in the mixed and pure forests
Discussion
Soil humus fraction and property
Soil organic matter content strongly affected soil fertility
on nutrient cycling and on the physical-chemical and
biological properties of soils. Humus was the most
important component of soil organic matter. Also, soil
humus represents a major pool of C in forest ecosystems.
The chemical composition of humus was understood
poorly because of the complexity of the soil-plant
interaction and the lack of reliable analytical methods. The
higher humic C content in soils of mixed forest suggested
that there are more favorable external environmental
conditions for the formation of soil humus in mixed forest
than in pure forest.
The decomposition and transformation of organic
material in soils ultimately resulted in the formation of fulvic
acids (FAs) and humic acids (HAs). Fulvic and humic acids
were important components in soil systems, and they were
able to strongly combine both essential and toxic elements.
In particular, the content and characteristic of soil HA
usually reflected humus quality. In this study, HA/FA ratios
in the mixed and pure forests were 0.40 and 0.36
respectively and both less than 0.5, which was similar to
the results of Yang (1996) for soil humus in the pure and
mixed Chinese fir stands in Nanping. The low HA/FA ratio
in this study agreed with the common findings (HA/FA ratio
less than 0.45) in red soils of subtropics (Xiong et al. 1990).
Optical properties of soil HA were often used to estimate
its molecular structure. There were higher E4 value and
lower E4/E6 ratio in the mixed forest, compared with the
corresponding parameter in the pure stand. Infrared
spectrum analysis had also exhibited relatively simple
chemical structure of soil humus in the pure Chinese fir
stand.
The composition and property of forest soil humus were
closely related to decomposability of aboveground litter
and fine roots (Yang et al.1997; 1998). However, it was
impossible to quantify the individual contribution of each of
these sources to humus formation. Differences in litter
quality in both stands played a major role in differentiating
the humus. Compared with broadleaves, needle litter with
lower N concentration, higher C/N ratio, and a higher
content of decay-resistant substrates (e.g., lignin and
tannins) decomposed slowly and allowed for the
accumulation of mor humus with a low degree of
humification (Berg et al. 1996). Especially, the amount of
acid insoluble (AIS) material in the litter would obviously
influence the proportion of the litter that became humus. In
forest floor of the mixed forest, there was more mull humus.
As well, in progressing from mor humus to mull humus,
there was a gradual increase in the degree of
decomposition. This, in turn, resulted in greater nutrient
availability. Overall, the type of humus greatly influenced
soil fertility.
Soil humus function
The importance of humus for the nutrition of forests had
been recognized for a long time. Gregorich et al. (1994)
proposed two essential functional roles of humus, which
was soil structure and nutrient storage. The addition of
humic substances to soils was effective in increasing the
YANG Yu-sheng et al. 36
amount and size of water-stable aggregates, especially in
soils with low total organic matter contents (Tisdall and
Oades 1982; Angers and Mehuys 1989). A better soil
structure in the mixed forest than that in the pure stand
could be testified by a higher content of soil water-stable
aggregates and a higher level of total porosity. Obviously,
the improvement of soil structure had a favorable effect on
soil aeration and water permeability, which benefited trees
growth. On the other hand, humus might also be view as a
nutrient sink, especially for nitrogen. This nutrient reserve
was critical to long-term site fertility, and helped to buffer
the site against disturbances that might lead to nutrient
depletion. In addition, intense biological activity resulted in
humus oxidation to CO2 and disorganization of the organo-
mineral complexes, and then available nutrients were
released correspondingly, which improved short-term
productivity.
In view of the ways of soil humus affecting soil fertility,
proper management of this resource entailed two rather
divergent considerations, that was, to conserve soil humus
in sites to protect long-term site productivity, and to
manipulate soil humus to increase nutrient release for
short-term productivity. Growing mixtures of species might
balance the two aspects, particularly if hardwoods were
interplanted with conifers (Yang 1998). This mixture effect
might be the result of the mycorrhizal associates of some
species, which is favorable to access organic forms of
nutrients. Higher nutrient availability found in Chinese fir
and Tsoong’s tree mixed forests seemed that soils in the
mixed forest provided better nutrient supply for the trees
and this silvicultural pattern could avoid soil degradation of
the pure Chinese fir forest.
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Chinese Abstracts ii
表明珍稀植物群落结构的复杂性和群落发展的相对稳定性。
表 5参 8。
关键词：珍稀植物群落；区系；生态特征；神农架
神农架地区珍稀植物沿河岸带的分布格局/江明喜（中国科学
院武汉植物研究所，武汉 430074），邓红兵（中国科学院沈
阳应用生态研究所，沈阳 110016），蔡庆华（中国科学院水
生生物研究所，武汉 430072）//Journal of Forestry Research.
–2002, 13(1): 25-27.
在神农架香溪河流域内不同海拔高度沿河岸带共设置
42个与河岸方向相同的10 m宽、100 m长样带进行植被调查，
发现河岸带分布有珍稀保护植物 14种，占神农架地区珍稀植
物总数的 42.4%，这些珍稀植物主要分布在 1200～1800 m山
地常绿阔叶林、落叶阔叶混交林带，表明在神农架地区植物
群落的物种多样性在中等海拔高度上最大。TWINSPAN分类可
把14种珍稀物种可划分为低海拔、中等海拔和较高海拔种组
3组，DCA排序也使 14种珍稀物种在反映海拔梯度的第一轴
可以得到很好的展示。本文还对河岸带珍稀植物分布格局的
成因进行了探讨，明确指出应重视河岸带在珍稀物种保护方
面的重要作用。图 3表 1参 9。
关键词：香溪河；珍稀植物；河岸带；格局；生物多样性保
护
马尾松实生种子园五年生的植株生长与分枝/赖焕林，王章荣
（南京林业大学森林资源与环境学院，南京 210037），江瑞
荣（福建省龙岩市林木种苗站，福建 364001）//Journal of
Forestry Research. –2002, 13(1): 28-32.
本文研究了马尾松实生种子园建立第五年时植株的生长
与分枝状况，研究的性状包括树高、胸径、枝条总数、年高
生长、 年枝条生长量、年分枝数、不同分枝处树干直径等。
对总的生长与分枝性状（含树高、胸径、枝条总数）分析表
明：家系间只在胸径方面存在显著差异。对分年度的生长与
分枝性状的研究表明：家系间在年高生长、年枝条生长量、
年枝条直径方面无显著差异；年分枝数在刚建立的前两年家
系间没有显著差异，后两年则差异显著；不同分枝处树干直
径在连续的四年内，家系间均存在显著差异。不同年度的生
长与分枝的趋势分析结果发现，大部分家系的年高生长与年
枝条生长呈递增型，而大部分家系每年的分枝数却为波动型。
这些研究结果表明，该马尾松实生种子园到建立的第五年时，
家系间的差异大部分都不显著。究其原因，一方面可能是马
尾松初期生长节律；另一方面可能是因为建园家系复杂的父
本构成。因此，这个时期进行家系选择不太有效，建议在利
用优树自由授粉子代建立实生种子园时，对他们先期进行苗
期选择，而不是采用所有的子代。图 1表 4参 20。
关键词： Pinus massoniana Lamb；分枝；生长；实生苗种
子园
杉木观光木混交林土壤腐殖质组成及特性/杨玉盛，郭剑芬，
刘艳丽，林瑞余，陈光水（福建农林大学，南平 353001）
//Journal of Forestry Research. –2002, 13(1): 33-36.
1999年1月对福建三明莘口教学林场杉木观光木混交林
及对照杉木纯林土壤腐殖质的有机碳和胡敏酸(HA)含量、
HA/FA、可见光谱、红外光谱特性等进行研究。结果表明，与
杉木纯林相比，混交林各土层土壤有机碳、胡敏酸含量及胡
敏酸的 E4值均有显著增加，HA/FA比值亦有所增加(不显著)，
而 E4/E6值略有降低，胡敏酸红外光谱在 1650 cm-1处出现明
显的吸收峰。可见混交林中土壤腐殖质腐殖化程度和芳香度
较纯林的高，这对土壤结构改良和有效养分供应有利，土壤
肥力有一定程度的提高。图 1表 1参 17。
关键词：杉木；观光木；混交林；土壤腐殖质组成；光学特
性
不同浓度氮源引起的红松苗木根际 pH 变化及其对 Fe、Mn、
Cu、Zn 有效性和吸收的影响/陈永亮，韩士杰，周玉梅（中
科院应用生态研究所，沈阳 110016），程国玲（东北林业大
学， 哈尔滨 150040）//Journal of Forestry Research. –2002,
13(1): 37-40.
在中科院长白山生态系统定位站，从地表 20cm处采集土
壤样品，用两种不同形式的氮肥（NO3--N，NH4+-N和NH4NO3）
处理土壤样品，用盆栽试验研究了两年生红松苗木受不同浓
度N源影响而产生的根际pH变化及其对根际 Fe、Mn、Cu和
Zn等微量元素的有效性和吸收的影响。结果表明，与对照处
理相比，施加铵态氮使根际pH降低，而施加硝态氮则使根际
pH增加。根际 pH变化的方向与程度取决于 N源及施加的浓
度。根际 pH的变化对根际微量元素的有效性具有显著影响，
进而影响到苗木对养分的吸收利用。根际有效 Fe、Mn、Cu
和 Zn的含量与根际 pH呈负相关，而苗木叶中 Fe、Mn、Cu
和 Zn含量与根际有效养分含量呈正相关。图 5参 11。
关键词：根际 pH；N源；微量元素；有效性；吸收
贵州省建造石头梯田对限制水土流失的效益和风险分析/杰
克.麦孔其（新西兰惠灵顿维多利亚大学地球科学学院地理研
究所），马焕成（西南林学院生态工程研究所，昆明 650224）
//Journal of Forestry Research. –2002, 13(1): 41-47.
在贵州全境建造石头梯田来减少水土流失的现象十分普
遍。但此项技术本身却有其固有的风险性。石头梯田通常比
土质的梯田高，填在石头挡墙中的土壤的量更大，更易导致
梯田的垮塌，也会减少梯田上部的土壤，降低土壤的养分和
水分含量。石头的挡墙会威胁土地的长期生产力，因为一旦
石头挡墙垮塌，所有的碎石就会堆积在下部的梯田中，使耕
作十分困难。这种垮塌现象会通过增加地表径流而形成冲沟，
使向下的沉积物运输增加。尤其是梯田之间的人工排水道使
这种风险加剧。因为这种排水道使降水很难渗人土壤中，使
土壤的保水和蓄水能力下降，从而造成作物的受旱。水流通
过排水道输送的速度加快，很容易造成水流的汇集，增加洪
水泛滥的可能性。由于建造了排水道，即使一般的暴雨，也
会因为输送速度的加快而导致洪峰升高而成灾。因此，对水
土流失的工程治理方式不应该取代、而应该与好的土地管理
策略相结合。尽管土地利用方式有所改变，但通过采用新技
术和坚持可持续发展的原则，在此类的土地上仍可获得最高
的产量。图 7表 1参 14。
关键词:水土流失；造林；梯田；可持续性；滑坡；环境管理
植物群落的竞争密度效果/薛立（华南农业大学林学院，广州
510642，中国）//Journal of Forestry Research. –2002, 13(1):
48-50.
植物种群的竞争密度效应在森林经营理论和实践中都有
着重要的意义，也是长期以来的研究内容。对在无自然稀疏
和有自然稀疏状况下有关植物群落的竞争密度效应的两个倒
数方程的差异进行了理论分析。这为分析森林种群的动态和
评价森林经营效果提供了理论依据。参 20。
关键词：竞争密度效果；自然稀疏群落；非自然稀疏群落