21. Biotic Manipulations Involving Belowground Animals
soil into the experimental set-up), or through air,
and confound experimental results. Laboratory and
"phytotron" experimenters need to be aware of
nontarget introductions. Nevertheless, the combination of manipulations, including laboratory or
greenhouse, offers increased information on the
role of soil biota in ecosystem processes.
Summary
Experimental manipulations of soil biota in ecological systems are difficult, especially in the field.
Relatively few variables can be effectively controlled without introducing undue artificiality, and
hence greater replication and attention to sample
sizes may be required to overcome naturally occurring, variation-inducing, effects. All of the problems to which aboveground manipulations are susceptible are magnified in the microscopic habitats
belowground. However, subterranean processes are
among the most important in virtually all ecosystems, and hence ecologists must apply new techniques and technologies, and creatively address the
important, unanswered questions in the soil. Molecularbiology (van der Knaap et al. 1993; Clegg
et al. 1995; Jones et al. 1997), image analysis systems, and isotopes (Boutton et al. 1983; Kuikman
et al. 1989; Freckman et al. 1991; Briones et al.
1999; Hobbie et al. 1999; Yeates 1999), are offering
new and exciting directions for evaluating soil organisms at the species or genus level and their roles
in the functioning in ecosystems. In particular, the
use of microbial tracers offers new strategies for
understanding the interaction of microbial "species" with other soil biota and their effect on plants
(Stephens et al. 1993; Clegg et al. 1995; Brimecombe et al. 2000). The challenge for ecologists is
to identify those techniques useful in soil biology,
such as identifying the flow of nitrogen through
micro arthropods using stable isotopes, or examining the distribution of soil biota related to water,
temperature, and vegetation with geographic information system (GIS) techniques, that will allow us
to increase our scale of understanding of the soil
biota and ecosystem processes.
References
Anderson, D.C. Belowground herbivory in natural communities: A review emphasizing fossorial animals. Q.
Rev. BioI. 62:261-286; 1987.
325
Anderson, lM.; Huish, S.A; Ineson, P.; Leonard, M.A;
Splatt, P.R. Interactions of invertebrates, microorganisms; tree roots in nitrogen; mineral element
fluxes in deciduous woodland soils. In: Fitter, AH.;
Atkinson, D.; Read, D.; Usher, M.B., eds. Ecological
Interactions in Soil. Oxford: Blackwell; 1985:377392.
Anderson, J.M.; Ingram, J.S.I. Tropical Soil Biology and
Fertility. A Handbook of Methods. 2nd ed. Wallingford, UK: CAB; 1993.
Andren, 0.; Bengstsson, l; Clarholrn, M. Biodiversity
and species redundancy among litter decomposers. In:
Collins, H.P.; Robertson, G.P.; Klug, MJ., eds. The
Significance and Regulation of Soil Biodiversity. Dordrecht, Netherlands: Kluwer; 1995:141-151.
Balogh, l; Balogh, P. The Oribatid Mite Genera of the
World. Vol. 1. Budapest: Hungarian National Museum
Pr.; 1992.
Barker, K.R.; Daughtry, B.I.; Corbett, D.W. Equipment
and techniques for establishing field microplots for the
study of soilborne pathogens. J. Nematol. 11:106107; 1979.
Beare, M.H.; Parmelee, R.W.; Hendrix, P.E; Cheng, w.;
Coleman, D.C.; Crossley, D.A, Jr. Microbial and faunal interactions and effects on litter nitrogen and decomposition in agroecosystems. Ecol. Monogr.
62:569-591; 1992.
Blair, lM. Fire, N availability and plant response in
grasslands: A test of the transient maxima hypothesis.
Ecology 78:2359-2368; 1997.
Blair, lM.; Bohlen, PJ.; Freckman, D.W. Soil invertebrates as indicators of soil quality. In: Doran, lW.;
Jones, AJ., eds. Methods for Assessing Soil Quality.
Madison, WI: Soil Science Society of America;
1996:273-291.
Boag, B.; Yeates, G.w.; Johns, P.M. Limitations to the
distribution and spread of terrestrial flatworms with
special reference to the New Zealand flatworm (Artioposthia triangulata). Pedobiologia 42:495-503; 1998.
Bohlen, P.l; Parmelee, R.W.; Blair, J.M.; Edwards, C.A.;
Stinner, B.R. Efficacy of methods for manipulating
earthworm populations in large-scale field experiments in agroecosystems. Soil BioI. Biochem.
27:993-999; 1995.
Boutton, T.W.; Arshad, M.A; Tieszen, L.L. Stable isotope analysis of termite food habits in East African
grasslands. Oecologia 59:1-6; 1983.
Bragg, T.B. The physical environment of Great Plains
grasslands. In: Joern, A; Keeler, K.H., eds. The
Changing Prairie. Oxford: Oxford University Pr.;
1995:48-81.
Brimecombe, MJ.; DeLeij, EAAM.; Lynch, J.M. Effect
of introduced Pseudomonas fluorescens strains on soil
nematode and protozoan populations in the rhizo-
soil into the experimental set-up), or through air,
and confound experimental results. Laboratory and
"phytotron" experimenters need to be aware of
nontarget introductions. Nevertheless, the combination of manipulations, including laboratory or
greenhouse, offers increased information on the
role of soil biota in ecosystem processes.
Summary
Experimental manipulations of soil biota in ecological systems are difficult, especially in the field.
Relatively few variables can be effectively controlled without introducing undue artificiality, and
hence greater replication and attention to sample
sizes may be required to overcome naturally occurring, variation-inducing, effects. All of the problems to which aboveground manipulations are susceptible are magnified in the microscopic habitats
belowground. However, subterranean processes are
among the most important in virtually all ecosystems, and hence ecologists must apply new techniques and technologies, and creatively address the
important, unanswered questions in the soil. Molecularbiology (van der Knaap et al. 1993; Clegg
et al. 1995; Jones et al. 1997), image analysis systems, and isotopes (Boutton et al. 1983; Kuikman
et al. 1989; Freckman et al. 1991; Briones et al.
1999; Hobbie et al. 1999; Yeates 1999), are offering
new and exciting directions for evaluating soil organisms at the species or genus level and their roles
in the functioning in ecosystems. In particular, the
use of microbial tracers offers new strategies for
understanding the interaction of microbial "species" with other soil biota and their effect on plants
(Stephens et al. 1993; Clegg et al. 1995; Brimecombe et al. 2000). The challenge for ecologists is
to identify those techniques useful in soil biology,
such as identifying the flow of nitrogen through
micro arthropods using stable isotopes, or examining the distribution of soil biota related to water,
temperature, and vegetation with geographic information system (GIS) techniques, that will allow us
to increase our scale of understanding of the soil
biota and ecosystem processes.
References
Anderson, D.C. Belowground herbivory in natural communities: A review emphasizing fossorial animals. Q.
Rev. BioI. 62:261-286; 1987.
325
Anderson, lM.; Huish, S.A; Ineson, P.; Leonard, M.A;
Splatt, P.R. Interactions of invertebrates, microorganisms; tree roots in nitrogen; mineral element
fluxes in deciduous woodland soils. In: Fitter, AH.;
Atkinson, D.; Read, D.; Usher, M.B., eds. Ecological
Interactions in Soil. Oxford: Blackwell; 1985:377392.
Anderson, J.M.; Ingram, J.S.I. Tropical Soil Biology and
Fertility. A Handbook of Methods. 2nd ed. Wallingford, UK: CAB; 1993.
Andren, 0.; Bengstsson, l; Clarholrn, M. Biodiversity
and species redundancy among litter decomposers. In:
Collins, H.P.; Robertson, G.P.; Klug, MJ., eds. The
Significance and Regulation of Soil Biodiversity. Dordrecht, Netherlands: Kluwer; 1995:141-151.
Balogh, l; Balogh, P. The Oribatid Mite Genera of the
World. Vol. 1. Budapest: Hungarian National Museum
Pr.; 1992.
Barker, K.R.; Daughtry, B.I.; Corbett, D.W. Equipment
and techniques for establishing field microplots for the
study of soilborne pathogens. J. Nematol. 11:106107; 1979.
Beare, M.H.; Parmelee, R.W.; Hendrix, P.E; Cheng, w.;
Coleman, D.C.; Crossley, D.A, Jr. Microbial and faunal interactions and effects on litter nitrogen and decomposition in agroecosystems. Ecol. Monogr.
62:569-591; 1992.
Blair, lM. Fire, N availability and plant response in
grasslands: A test of the transient maxima hypothesis.
Ecology 78:2359-2368; 1997.
Blair, lM.; Bohlen, PJ.; Freckman, D.W. Soil invertebrates as indicators of soil quality. In: Doran, lW.;
Jones, AJ., eds. Methods for Assessing Soil Quality.
Madison, WI: Soil Science Society of America;
1996:273-291.
Boag, B.; Yeates, G.w.; Johns, P.M. Limitations to the
distribution and spread of terrestrial flatworms with
special reference to the New Zealand flatworm (Artioposthia triangulata). Pedobiologia 42:495-503; 1998.
Bohlen, P.l; Parmelee, R.W.; Blair, J.M.; Edwards, C.A.;
Stinner, B.R. Efficacy of methods for manipulating
earthworm populations in large-scale field experiments in agroecosystems. Soil BioI. Biochem.
27:993-999; 1995.
Boutton, T.W.; Arshad, M.A; Tieszen, L.L. Stable isotope analysis of termite food habits in East African
grasslands. Oecologia 59:1-6; 1983.
Bragg, T.B. The physical environment of Great Plains
grasslands. In: Joern, A; Keeler, K.H., eds. The
Changing Prairie. Oxford: Oxford University Pr.;
1995:48-81.
Brimecombe, MJ.; DeLeij, EAAM.; Lynch, J.M. Effect
of introduced Pseudomonas fluorescens strains on soil
nematode and protozoan populations in the rhizo-