全 文 ：开放式空气 CO2 浓度增高对中国稻田生态
系统线虫营养类群产生的影响 3
梁文举1 3 3 　李　琪1 　陈立杰1 　黄国宏1 　朱建国2
(1 中国科学院沈阳应用生态研究所 , 沈阳 110016 ;2 中国科学院南京土壤研究所 ,南京 210008)
【摘要】　土壤动物在农田生态系统腐屑食物网中占有重要地位 ,它们参与土壤有机质分解、植物营养矿化
及养分循环作用. 国内外许多研究表明 ,土壤动物对全球变化 ,尤其是大气 CO2 浓度升高能够产生正向、
中性和负向的影响. 土壤线虫是这类土壤动物的典型代表 ,因为它们在大多数土壤中分布是丰富的 ,而且
营养类群是多样的. 应用自由空气 CO2 浓度增高 ( FACE) 技术设计 3 个处理水稻圈暴露在大气 CO2 增高
(浓度为 570μmol·mol - 1)条件下 ,3 个对照水稻圈为环境中的 CO2 浓度 (370μmol·mol - 1) . 在中国无锡稻田
生态系统水稻生长期内 ,本项研究监测了 0～5cm 和 5～10cm 土层中线虫营养类群. 研究结果显示 ,线虫
总数、食细菌线虫、植物寄生线虫、杂食2捕食类线虫在取样深度和取样日期上存在显著差异 ;在整个取样
日期中 ,FACE处理 5～10cm 深度中线虫总数、食细菌线虫数量比对照中的高 ;在 0～5cm 深度中 , FACE
处理食细菌线虫数量比对照中的高 ,而杂食2捕食类线虫数量则表现出相反的趋势. 食真菌线虫在 FACE
处理与对照之间也存在极显著差异.
关键词 　CO2 浓度增高 　土壤线虫 　营养类群 　稻田生态系统
文章编号 　1001 - 9332 (2002) 10 - 1269 - 04 　中图分类号 　S511 　文献标识码 　A
Effects of elevated atmospheric CO2 on nematode trophic groups in a Chinese paddy2f ield ecosystem. L IAN G
Wenju1 ,L I Qi1 ,CHEN Lijie1 , HUAN G Guohong1 ,ZHU Jianguo2 (1 Institute of A pplied Ecology , Chinese A2
cademy of Sciences , S henyang 110016 , P. R . China ;2 Institute of Soil Science , Chinese Academy of Sciences ,
N anjing 210008 , P. R . China) . 2Chin. J . A ppl . Ecol . ,2002 ,13 (10) :1269～1272.
Soil fauna plays significant roles in the detritus food webs of agroecosystems , they are the essential contributors to
the decomposition of soil organic matter , mineralization of plant nutrients and nutrient cycling. Some evidences
indicate that soil fauna of the detritus food webs appears to show positive , neutral or negative responses to global
change , especially atmospheric CO2 enrichment across different studies. Soil nematodes are representative of a
large portion of this fauna , since they are abundant and trophically diverse in most soils. The free2air CO2 enrich2
ment ( FACE) technology was used to expose three plots of rice ( Oryz a sativa) under elevated (ambient +
200μmol·mol - 1) atmospheric CO2 , while three control plots were outfitted with FACE apparatus under ambient
CO2 . Nematode trophic groups were monitored in this study at depths of 0～5 cm and 5～10 cm during rice
jointing and ripening stages in Wuxi site , China. Significant differences were found between depths and sampling
dates in the total numbers of nematodes , bacterivores , plant parasites and omnivores2predators during the study
period. The total numbers of nematodes and bacterivores at the 5～10 cm depth were higher in treatment plots
than in control plots across all sampling dates. At 0～5 cm depth , the numbers of bacterivores were higher in
treatment plots than in control plots , while those of omnivores2predators exhibited an inverse trend during the
study period. Significant differences were also observed between treatment plots and control plots in the numbers
of fungivores in our experiment .
Key words 　Free2air CO2 enrichment , Soil nematodes , Trophic groups , Paddy2field ecosystem.3 中国科学院知识创新重要方向项目 ( KZCX22408) 、国家自然科学
基金重大国际合作研究资助项目 (40120140817) .
本文于 2002 年 8 月 11～18 日在韩国汉城举行的第八届国际生态学
大会上做了发言. This research was supported by the Foundation of
Knowledge Innovation Program of the Chinese Academy of Sciences
( KZCX22408) . Presented to Ⅷ International Congress of Ecology , Au2
gust 11～18 , 2002 , COEX Convention Center , Seoul , Korea.3 3 通讯联系人 Corresponding author. Tel. : + 86224223916236 ;fax :
+ 86224223843313. E2mail : liangwj @iae. ac. cn
Received 2002 - 06 - 12 ,Accepted 2002 - 08 - 18.
1 　INTROD UCTION
Soil fauna plays significant roles in the detritus
food webs of agroecosystems. They are the essential
contributors to the decomposition of soil organic mat2
ter , mineralization of plant nutrients and nutrient cy2
cling. Some evidences indicate that soil fauna of the
detritus food webs appears to show positive , neutral
or negative responses to global change , especially at2 mospheric CO2 enrichment across different stud2ies[4 ,13 ] . The direct impact of elevated concentrations
应 用 生 态 学 报 　2002 年 10 月 　第 13 卷 　第 10 期 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　
CHIN ESE JOURNAL OF APPL IED ECOLO GY ,Oct . 2002 ,13 (10)∶1269～1272
of CO2 on the soil fauna are likely to be negligible be2
cause these organisms are already adapted to the al2
ready high CO2 concentration in the soil [11 ] . Howev2
er , indirect effects , such as changes in the quality and
quantity of litter , and global warming are expected to
affect their density , biomass and the communities[1 ] .
Soil nematodes are representative of a large portion of
this fauna , since they are abundant and trophically di2
verse in most soils[2 ] .
The effects of elevated CO2 on rhizosphere pro2
cesses , including the response of soil faunal popula2
tions and community st ructure , have so far received
little attention [15 ] . Previous work looking at the ef2
fects of elevated CO2 on soil nematodes has generally
focused on only grassland and forest ecosys2
tems[2 ,3 ,8 ,9 ,12 ,14 ,16 ] . Most studies examining respons2
es of soil nematodes to increased root production re2
sulting from experimentally elevated atmospheric CO2
have reported increased total densities[3 ,10 ,16 ] . Popu2
lations of saprophagous nematodes increased at elevat2
ed CO2 in a FACE experiment with cotton[10 ] . So
far , there is little information about the effects of ele2
vated CO2 on soil nematode trophic groups in Chinese
farmland ecosystems.
The purpose of this work was to determine the
effects of elevated CO2 on soil nematode trophic
groups in a Chinese paddy2field ecosystem , where rice
( O ryz a sativa ) was grown under both ambient
(370μmol·mol - 1) and elevated (ambient + 200μmol·
mol - 1) atmospheric CO2 .
2 　MATERIALS AND METHODS
The field work in this study was conducted at
the Nianyu Farm (31°37′N , 120°28′E) , Wuxi Mu2
nicipality , J iangsu Province , China. The station is in
the subtropical marine climatic zone. Annual mean
temperature is 16 ℃. Annual precipitation averages
1000～1200 mm. The length of annual non2f rost pe2
riod is around 230 days. The soil at the study site is
classified as anthropogenic2alluvial soil. Rice2wheat
rotation system is dominant in this region. The field
site was planted in rice . Chemical N2and P2fertilizers
for rice were utilized at a rate of 250 kg·hm - 2 and 35
kg·hm - 2 , respectively. The free2air CO2 enrichment
( FACE) technology was used to expose three plots of
rice under elevated (ambient + 200μmol·mol - 1) at2
mospheric CO2 , while three control plots were outfit2
ted with FACE apparatus under ambient CO2 .
During rice growing season , the samplings were
taken at depths of 0～5 cm and 5～10 cm on 3 Au2
gust ( rice jointing stage ) , 27 August ( heading
stage) , 24 September (filling stage) , and 27 October
(ripening stage) , respectively. Each soil sample com2
prised 5 cores (5cm diameter) ; subsamples were tak2
en from each such bulk sample for estimation of ne2
matode populations and soil chemistry. The samples
were protected against overheating , and processed
within 7 days. Soil moisture was determined gravi2
metrically by drying samples at 105 ℃ for 48 h and
expressed as a percentage of dry weight [5 ] .
Nematodes were extracted from 100 g ( f resh
weight) of soil f rom each sample using sugar flotation
and centrifugation[2 , 7 ] , and nematode populations
were expressed per 100 g dry weight soil [5 ,6 ] . All ex2
t racted nematodes in each sample were counted , and
up to 30 nematodes in each sample were identified us2
ing an inverted compound microscope. The classifica2
tion of t rophic groups was assigned to : (1) bacteri2
vores ; (2) fungivores ; (3) plant2parasites ; and (4)
omnivore2predators based on known feeding habitats
or stoma and esophageal morphology[5～7 ] .
All the data across 5 sampling dates were sub2
jected to statistical analysis of variance (ANOVA) .
Differences with P < 0. 05 were considered signifi2
cant .
3 　RESULTS
311 　Total numbers of nematodes
　　The total number of nematodes ranged between
66 and 615 individuals per 100 g dry soil during the
study period. The total numbers of nematodes at the
5～10 cm depth were higher in the treatment plots
than in the control plots during the study period
( Fig. 1) . Those at the 0～5 cm depth were lower in
the treatment plots than in the control plots across
rice jointing and heading stages. The total number of
nematodes at the 0～5cm depth in the treatment plots
reached a maximum value (615 ±109) at filling stage
( Fig. 1) . Significant differences were found between
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sampling dates ( P < 0. 01) and between depths ( P <
0. 01) , however , no significant differences were ob2
served between treatments in the total numbers of ne2
matodes during the study period ( Table 1) .
312 　Trophic groups
　　In this study , the populations of bacterivores at
both depths were higher in the treatment plots than
in the control plots during the study period ( Table
2) . Significant differences were found between sam2
pling dates ( P < 0. 01) , t reatments ( P < 0. 05) and
depths ( P < 0. 01) in the bacterivore group ( Table
1) .
　　The populations of fungivores at both depths
were higher in the treatment plots than in the control
plots across heading , filling and ripening stages
( Table 2) . Significant differences were found between
sampling dates ( P < 0. 01) and treatments ( P <
0. 01) , no significant differences were observed be2
tween depths in the fungivore group ( Table 1) .
　　Plant parasites were the most abundant t rophic
groups under two treatments and at both depths , and
the relative abundance averaged 53. 8 %. The popula2
tions of plant - parasites at 0～5 depth were lower in
the treatment plots than in the control plots across
jointing , heading and ripening stages. However , they
exhibited an inverse trend at filling stage ( Table. 2) .
Significant differences were found between sampling
dates ( P < 0. 01) and depths ( P < 0. 01) , and no
significant differences were obtained between treat2
ments in the plant parasite group ( Table 1) .
Fig. 1 Changes in total numbers of nematodes in both treatments and
both depths during the study period.
Table 1 ANOVA for total nematodes and trophic groups
Index Season
F2test P value TreatF2test Pvalue DepthF2test P value
Total nematodes 36. 43 < 0. 0001 2. 15 NS 50. 50 < 0. 0001
Trophic groups
BF 8. 51 0. 0003 4. 41 0. 0438 5. 25 0. 0287
FF 12. 08 < 0. 0001 9. 26 0. 0047 0. 90 NS
PP 32. 20 < 0. 0001 0. 35 NS 30. 31 < 0. 0001
OP 15. 64 < 0. 0001 0. 91 NS 38. 50 < 0. 0001
Table 2 Absolute abundance of nematode trophic groups in both treat2
ments and depths during the study period
Trophic group 3 Ambient
0～5cm 5～10cm
FACE
0～5cm 5～10cm
Jointing stage
BF 19 ±3 3 3 14 ±6 18 ±14 18 ±5
FF 7 ±5 3 ±5 3 ±2 6 ±6
PP 80 ±24 30 ±23 48 ±30 15 ±9
OP 55 ±8 18 ±19 40 ±25 8 ±26
Heading stage
BF 33 ±14 4 ±11 38 ±23 19 ±6
FF 0 ±0 2 ±3 0 ±0 2 ±4
PP 159 ±90 50 ±21 120 ±15 61 ±22
OP 137 ±68 27 ±27 71 ±28 16 ±14
Filling stage
BF 76 ±22 37 ±18 161 ±108 59 ±12
FF 3 ±5 0 ±0 19 ±33 5 ±5
PP 223 ±90 172 ±54 304 ±15 174 ±78
OP 157 ±66 20 ±4 131 ±22 45 ±8
Ripening stage
BF 6 ±7 21 ±5 52 ±41 30 ±20
FF 11 ±10 12 ±11 49 ±20 36 ±15
PP 98 ±58 70 ±15 70 ±34 55 ±9
OP 5 ±8 11 ±10 5 ±21 11 ±123Trophic groups : BF , Bacterivores ; FF , Fungivores ; PP , Plant - para2
sites ; OP , Omnivore2predators. 3 3 Each entry represents an arithmetic
mean ±standard deviation , each mean value is expressed as individuals
per 100 g dry soil.
　　Omnivore2predators at 0～5 cm depth were low2
er in the treatment plots than in the control plots dur2
ing the study period ( Table 2) . Significant differ2
ences were found between sampling dates ( P < 0. 01)
and between depths ( P < 0. 01) , and no significant
differences were observed between treatments in
theomnivore2predator group ( Table 1) .
4 　DISCUSSION
　　The number of total nematodes in our experi2
mental plots (212 individuals per 100 g dry soil) was
higher than that obtained in Hailun site ( 159) [7 ] .
Plant parasites were the most abundant t rophic group
in two treatments and both depths , averaging 53. 8 %
of the nematode community. Fungivores were the
least abundant group in our experimental plots
( 4. 7 %) . These results exhibited different t rends
compared with those observed in Hailun site[7 ] ,
where bacterivores were most abundant group . One
explanation for these differences is that there were
172110 期 　　　　　　　　梁文举等 :大气 CO2 浓度升高对中国稻田生态系统线虫营养类群产生的影响 　　　　　　　　　　　
differences in climate and soil types between the Wuxi
site and the Hailun site.
　　In terrest rial ecosystems , the effects of elevated
CO2 on carbon cycling result f rom pattern of t ranslo2
cation of C within the plant and its t ransformation by
microorganisms. These are , in turn , controlled by
the interactions between soil fauna and these micro2
bial communities[1 ] . Elevated concentrations of CO2
are unlikely to have any direct effects on the soil fauna
because soil biota is usually exposed to high concen2
t rations in the soil atmosphere. Nevertheless ,
changes in microbial biomass and composition have
showed a possible shift in faunal communities in re2
sponse to modification in the food supply[1 ] . In some
experiments , where plants were grown under elevat2
ed CO2 , responses of nematode trophic groups have
been examined. No significant differences in the total
abundance of nematodes and their t rophic groups in a
pasture soil were observed by Newton et al. [9 ] . No
significant differences in the densities of most types of
nematodes in the rhizosphere of cotton were also
found under 350 and 550μmol·mol - 1 in a FACE ex2
periment [10 ] . Our experiment supported the two
studies in the number of total nematodes. Bacteri2
vores and fungivores exhibited significant effects in
rice fields between ambient and elevated (ambient +
200μmol·mol - 1 ) atmospheric CO2 . The number of
bacterivores at both depths was significantly higher
under FACE in our study. This result was similar to
that observed by Yeates et al. in New Zealand[16 ] .
The absolute abundance of fungivores at both depths
was significantly higher under FACE than under am2
bient CO2 . The result did not support that reported
by Yeates et al. in grassland soil [16 ] .
　　Long2term studies are necessary to determine the
effect of soil carbon and nit rogen inputs under elevat2
ed CO2 on soil nematodes. The soil food chain re2
sponse to elevated CO2 is important to indicate the
changes in soil ecosystem process and implement nu2
t rient management in farmland ecosystems. In order
to understand the effects of elevated CO2 on soil ne2
matodes with similar habitats , further studies should
be conducted according to information on nematode
genera/ family and nit rogen input levels in farmland e2
cosystems.
Acknowledgements 　　The authors wish to express their ap2
preciation to Prof . Yosef Steinberger ( Faculty of Life Sciences ,
Bar2Ilan University , Israel ) for statistical analysis and Mr.
Weiguang Li and Mr. Guoqiang Xu ( Institute of Applied Ecolo2
gy , Chinese Academy of Sciences) for technical assistance.
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Wenju Liang is a research professor from Institute of Applied E2
cology , Chinese Academy of Sciences (CAS) , and the director
of Shenyang Experimental Station of Ecology , CAS. He got his
Ph. D. degree in 1995 in research field of agroecology. He is
currently the chief scientist on a project from China Ministry of
Science and Technology entitled“Research on New2type high2
efficiency Fertilizers and Their Industrialization”. His research
focuses on agroecosystem health , plant nutrition ,interactions be2
tween soil fauna and microbiota.
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