Eukaryotic Algae

The temporarily or permanently wet margins of rivers, lakes, and ponds and the peaty substrates of bogs and fens are home to many freshwater algae that do not thrive far from water. These may be referred to as the hydroterrestrial algae. However, the diverse soils of temperate and tropical agriculture, grasslands, forests, arctic and alpine tundra, and even deserts also harbor a surprisingly diverse and active flora of both eukaryotic algae and cyanobacteria. These are referred to as terrestrial algae, or sometimes as "edaphic algae." Cryptobiotic crusts (formed by eukaryotic algae together with filamentous fungi, yeasts, and cyanobacteria) are termed "epedaphic." General discussion or conclusions regarding the algal flora of soil and its functioning are hampered by historic taxonomic confusion and by literature up to the present day in which the numbers and activities of cyanobac-teria are included together with those of eukaryotic algae. The roles of these two groups in the soil nitrogen cycle are vastly different, since common soil cyanobac-teria such as Nostoc, Anabaena, Tolypothrix, Scytonema, and Cylindrospermum are highly active in nitrogen fixation, with rates often 20-30kg ha-1 year-1 (Zackrisson et al., 2004); rates in desert soil crusts are lower (1.4-9kg ha-1 year-1) and dependent upon taxonomic composition, moisture, and suitable temperatures (Belnap, 2002). There is room for a great deal of research to tease out the particular roles and quantitative significance of the various eukaryotic algae in soil.

However, in general, it can be said that they play an important role in net primary production and the incorporation of organic carbon and nitrogen into soil, crucial during primary succession on land created by volcanic activity or bared by the retreat of glaciers. Upon their death, much of this organic matter is generally readily accessible to microbial decomposition and enters the actively cycling nutrient pool. A small part, made up of cell wall materials and exudates, may become com-plexed with soil phenolics of plant origin and form more stable humic substances that help to provide soil structure. Together with soil fungi and some other microbes, terrestrial algae may also be responsible for liberation of nutrients from insoluble sources in the mineral fraction or horizon of soil (Metting, 1981; Jongmans et al., 1997). Finally, in many dune or desert environments where vascular plant growth is restricted by permanent or seasonal drought, eukaryotic algae alone or in mixed cryptobiotic crusts play a vital role in stabilizing the "soil" surface, gradually adding soil organic matter that holds soil moisture and provides nutrients for plant establishment.

Soil is a common habitat for nonmotile green algae. Both filamentous and coccoid forms occur, the latter more common in desert soils. Green algae tend to dominate the algal flora of acid soils, and some are observed only following enrichment culturing. Frequent genera include Actinochloris, Ankistrodesmus, Bracteacoccus, Characium, Chlorella, Chlorococcum, Chlorosarcinopsis, Fernandinella, Hormotilla, Keratococcus, Muriella, Protosiphon, Stichococcus, Tetracystis, Apatococcus, Desmococcus, Klebsormidium, and Ulothrix. Most are limited to the surface of wet soils, and some are epiphytic on algae or mosses. Trentepohlia forms long, brilliant orange filaments on soil-free rocks and bark, often not recognized as a green alga even by those who notice it. In this and many other Chlorophyta, pho-toprotective carotenoids mask the "typical" grass green color.

Red algae are infrequent in typical soils. Species of Cyanidium are found in and around acidic hot springs and species of Porphyridium grow as reddish gelatinous masses encrusting polluted, ammonium-rich soils in shaded areas and on wet, well-decayed logs. Both are spherical unicells with a mucilaginous matrix.

Species of Euglena (fusoid, uniflagellate cells with red eyespot and with or without chloroplasts) are abundant where moisture, organic matter, and often ammonium are high, such as wet footprints in paddocks, puddles, ditches, and farm ponds. Facultative photoautotrophs, they can subsist as achlorophyllous heterotrophs. The nonphotosynthetic, phagotrophic Peranema also frequents similar habitats.

Members of the golden-green algae (Xanthophyta) are usually found on the surface of moist soils. Vegetative cells are nonmotile and exhibit a variety of growth forms, from unicellular and globose or cylindrical to colonial and coenocytic, or filamentous. Genera reported from soil include Botrydiopsis, Botrydium, Bumilleria, Bumilleriopsis, Heterococcus, Vaucheria, and Xanthonema (=Heterothrix).

Diatoms form beautiful exoskeletons (frustules) of silica; deposits of millennia form diatomaceous earth, which can be used as a natural insecticide. Marine diatoms are probably the single largest primary producers in the world, and diatoms are also abundant in freshwater ecosystems. In terrestrial ecosystems, diatoms occur primarily in neutral to slightly alkaline soils, where their populations may reach 105 cells per gram dry weight of soil (Berard et al., 2004). Members of the genera Achnanthes, Cymbella, Fragilaria, Hantzschia, Navicula, Pinnularia, Stauroneis, and Surirella (many of which are admittedly artificial) are frequently reported. These are organisms of moist surfaces, including plants, other algae, litter, and bare mineral or organic soil.

For reviews of terrestrial algae, see Metting (1981) and Hoffmann (1989); useful taxonomic references include Foged (1978), Dodd (1987), Entwisle et al. (1997), Ling and Tyler (2000), John et al. (2002), and Wehr and Sheath (2003). As with much of biology, much more is known about these organisms in temperate (especially north temperate) regions of the world, but the biological roles of terrestrial algae everywhere deserve considerably more study.

references and suggested reading

Agrios, G. N. (1997). "Plant Pathology." 4th ed. Academic Press, San Diego.

Alexopoulos, C. J., Mims, C. W., and Blackwell, M. (1996). "Introductory Mycology." 4th ed. Wiley, New York.

Baldauf, S. L. (2003). The deep roots of eukaryotes. Science 300, 1701-1703.

Baldauf, S. L., and Doolittle, W. F. (1997). Origin and evolution of the slime molds (Mycetozoa). Proc.

Natl. Acad. Sci. USA 94, 12007-12012. Barnett, J. A., Payne, R. W., and Yarrow, D. (1990). "Yeasts: Characteristics and Identification."

2nd ed. Cambridge Univ. Press, Cambridge, UK. Barr, D. J. S. (2001). Chytridiomycota. In "The Mycota," Vol. VII, "Systematics and Evolution" (D. J. McLaughlin, E. G. McLaughlin, and P. A. Lemke, eds.), Part A, pp. 93-112. Springer-Verlag, Berlin.

Bass, D., and Cavalier-Smith, T. (2004). Phylum-specific environmental DNA analysis reveals remarkably high global biodiversity of Cercozoa (Protozoa). Int. J. Syst. Evol. Microbiol. 54, 2393-2404.

Belnap, J. (2002). Nitrogen fixation in biological soil crusts from southeast Utah, USA. Biol. Fertil. Soils 35, 128-135.

Belnap, J., and Lange, O. L. (2001). "Biological Soil Crusts: Structure, Function, and Management."

Ecological Studies 150. Springer-Verlag, Berlin. Benny, G. L. (2001). Trichomycetes. In "The Mycota," Vol. VII, "Systematics and Evolution" (D. J.

McLaughlin, E. G. McLaughlin, and P. A. Lemke, eds.), Part A, pp. 147-160. Springer-Verlag, Berlin. Benny, G. L., Humber, R. A., and Morton, J. B. (2001). Zygomycetes. In "The Mycota," Vol. VII, "Systematics and Evolution" (D. J. McLaughlin, E. G. McLaughlin, and P. A. Lemke, eds.), Part A, pp. 113-146. Springer-Verlag, Berlin. Bérard, A., Rimet, F., Capowiez, Y., and Lebulanger, C. (2004). Procedures for determining the pesticide sensitivity of indigenous soil algae: a possible bioindicator of soil contamination? Arch. Environ. Contam. Toxicol. 46, 24-31. Bigelow, D. M., Olsen, M. W., and Gilbertson, R. L. (2005). Labyrinthula terrestris sp. nov., a new pathogen of turf grass. Mycologia 97, 185-190. Bills, G. F., and Polishook, J. D. (1994). Abundance and diversity of microfungi in leaf litter of a lowland rain forest in Costa Rica. Mycologia 86, 187-198. Braselton, J. P. (2001). Plasmodiophoromycota. In "The Mycota," Vol. VII, "Systematics and Evolution" (D. J. McLaughlin, E. G. McLaughlin, and P. A. Lemke, eds.), Part A, pp. 81-91. Springer-Verlag, Berlin.

Brodo, I. M., Sharnoff, S. D., and Sharnoff, S. (2001). "Lichens of North America." Yale Univ. Press, New Haven, CT.

Brundrett, M. C. (2002). Coevolution of roots and mycorrhizas of land plants. New Phytol. 154, 275-304.

Cavalier-Smith, T. (2004). Only six kingdoms of life. Proc. R. Soc. B-Biol. Sci. 271, 1251-1262.

Christensen, M. (1981). Species diversity and dominance in fungal communities. In "The Fungal Community" (D. T. Wicklow and G. C. Carroll, eds.), pp. 201-232. Dekker, New York.

Cooke, R. C., and Rayner, A. D. M. (1984). "Ecology of Saprotrophic Fungi." Longman, London.

Corradi, N., Hijri, M., Fumagalli, L., and Sanders, I. R. (2004). Arbuscular mycorrhizal fungi (Glomeromycota) harbour ancient fungal tubulin genes that resemble those of the chytrids (Chytridiomycota). Fungal Genet. Biol. 41, 1037-1045.

Dick, M. W. (2001). "Stramenipilous Fungi." Kluwer Academic, Dordrecht.

Dighton, J. White, J. F., and Oudemans, P., eds. (2005). "The Fungal Community: Its Organization and Role in the Ecosystem." 3rd ed. Taylor & Francis, Boca Raton. [1st ed. (1981), D. T. Wicklow, and G. C. Carroll, eds., Dekker, New York, and 2nd ed. (1992), G. C. Carroll, and D. T. Wicklow, eds., Dekker, New York, are both useful and independent volumes.]

Dix, N. J., and Webster, J. (1995). "Fungal Ecology." Chapman & Hall, London.

Dodd, J. J. (1987). "Diatoms: Illustrated Flora of Illinois" (R. H. Mohlenbrock, ed.). Southern Illinois Univ. Press, Carbondale.

Domsch, K. H., Gams, W., and Anderson, T.-H. (1993). "Compendium of Soil Fungi." Academic Press, New York.

Ellis, M. B. (1971). "Dematiaceous Hyphomycetes." Commonwealth Mycol. Inst., Kew, UK.

Ellis, M. B. (1976). "More Dematiaceous Hyphomycetes." Commonwealth Mycol. Inst., Kew, UK.

Entwisle, T. J., Sonneman, J. A., and Lewis, S. H. (1997). "Freshwater Algae in Australia: a Guide to Conspicuous Genera." Sainty, Potts Point, NSW, Australia.

Erwin, D. C., Bartnicki-Garcia, S., and Tsao, P. H., eds. (1983). "Phytophthora: Its Biology, Taxonomy, Ecology, and Pathology." Am. Phytopathol. Soc., St. Paul, MN.

Farr, D. F., Bills, G. F., Chamuris, G. P., and Rossman, A. Y. (1989). "Fungi on Plants and Plant Products in the United States." Am. Phytopathol. Soc., St. Paul, MN.

Fell, J. W., Boekhout, T., Fonseca, A., and Sampaio, J. P. (2001). Basidiomycetous yeasts. In "The Mycota," VII, "Systematics and Evolution" (D. J. Mclaughlin, E. G. McLaughlin, and P. A. Lemke, eds.), Part B, pp. 1-36. Springer-Verlag, Berlin.

Foged, N. (1978). Diatoms in eastern Australia. Bibl. Phycol. 41, 1-242.

Fuller, M. S. (2001). Hyphochytriomycota. In "The Mycota," Vol. VII, "Systematics and Evolution" (D. J. McLaughlin, E. G. McLaughlin, and P. A. Lemke, eds.), Part A, pp. 73-80. Springer-Verlag, Berlin.

Fuller, M. S., and Jaworski, A. (1987). "Zoosporic Fungi in Teaching and Research." Southeastern Pub., Athens, GA.

Gargas, A., Depriest, P. T., Grube, M., and Tehler, A. (1995). Multiple origins of lichen symbioses in fungi suggested by SSU rDNA phylogeny. Science 268, 1492-1495.

Garrett, S. D. (1963). "Soil Fungi and Soil Fertility." Pergamon, Oxford, UK.

Gerdemann, J. W., and Trappe, J. M. (1974). The Endogonaceae in the Pacific Northwest. Mycol. Mem. 5, 1-76.

Gilbertson, R. L., and Ryvarden, L. (1986-1987). "North American Polypores," Vols. 1 and 2. Fungiflora, Oslo.

Hale, M. E. (1983). "The Biology of Lichens." 3rd ed. Arnold, London.

Hibbett, D. S., and Thorn, R. G. (2001). Homobasidiomycetes. In "The Mycota," Vol. VII, "Systematics and Evolution" (D. J. McLaughlin, E. G. McLaughlin, and P. A. Lemke, eds.), Part B, pp. 121-168. Springer-Verlag, Berlin.

Hoffmann, L. (1989). Algae of terrestrial habitats. Bot. Rev. 55, 77-105.

Holliday, P. (1989). "A Dictionary of Plant Pathology." Cambridge Univ. Press, Cambridge, UK.

James, T. Y., Kauuf, F., Schoch, C. L., Matheny, P. B., Hofstetter, V., Cox, C. J., Celio, G., Gueidan, C., Fraker, E., Miadlikowska, J., Lubsch, H. T., Rauhut, A., Reeb, V., Arnold, A. E., Amtoft, A., Stajich, J. E., Hosaka, K., Sung, G. H., Johnson, D., O'Rourke, B., Crockett, M., Biner, M., Curtis, J. M., Slot, J. C., Wang, Z., Wilson, A. W., Schuessler, A., Longcore, E., O'Donnell, K., Mozley-Standridge, S., Porter, D., Letcher, P. M., Powell, M. J., Taylor, J. W., White, M. M., Griffith, G. W., Davies, D. R., Humber, R. A., Morton, J. B., Sugiyama, J., Rossman, A. Y., Rogers, J. D., Pfister, D. H., Hewitt, D., Hansen, K., Hambleton, S., Shoemaker, R. A., Kohlmeyer, J., Volkmann-Kohlmeyer, B., Spotts, R. A., Serdani, M., Crous, P. W., Hughes, K. W., Matsuura, K., Langer, E., Langer, G., Untereiner, W. A., Lucking, R., Budel, B., Geiser, D. M., Aptroot, A., Diederich, P., Schmitt, I., Schulz, M., Yahr, R., Hibbett, D. S., Lutzoni, F., McLaughlin, D. J., Spatafora, J. W., and Vilgalys, R. (2006). Reconstructing the early evolution of Fungi using a six-gene phylogeny. Nature 443, 818-822.

John, D. M., Whitton, B. A., and Brook, A. J. (2002). "The Freshwater Algal Flora of the British Isles: an Identification Guide to Freshwater and Terrestrial Algae." Cambridge Univ. Press, Cambridge, UK.

Jongmans, A. G., van Breeman, N., Lundstrom, U., van Hees, P. A. W., Finlay, R. D., Srinivasan, M., Unestam, T., Giesler, R., Melkerud, P. A., and Olsson, M. (1997). Rock-eating fungi. Nature 389, 682-683.

Jülich, W., and Stalpers, J. A. (1980). "The Resupinate Non-poroid Aphyllophorales of the Temperate Northern Hemisphere." North-Holland, Amsterdam.

Karling, J. S. (1977). "Chytridiomycetarum Iconographia." J. Cramer, Vaduz, Liechtenstein.

Kirk, P. M., Cannon, P. F., David, J. C., and Stalpers, J. (2001). "Dictionary of the Fungi." 9th ed. CAB Int., Wallingford, UK.

Klich, M. A. (2002). "Identification of Common Aspergillus Species." Centraalbureau voor Schimmelcultures, Utrecht.

Kurtzman, C. P., and Fell, J. W., eds. (1998). "The Yeasts: a Taxonomic Study." 4th ed., Elsevier, Amsterdam.

Kurtzman, C. P., and Sugiyama, J. (2001). Ascomycetous yeasts and yeastlike taxa. In "The Mycota," Vol. VII, "Systematics and Evolution" (D. J. McLaughlin, E. G. McLaughlin, and P. A. Lemke, eds.), Part A, pp. 179-200. Springer-Verlag, Berlin.

Lachance, M. A., and Starmer, W. T. (1998). Ecology and yeasts. In "The Yeasts, a Taxonomy Study." 4th ed. (C. P. Kurtzman and J. W. Fell, eds.), pp. 21-30. Elsevier, Amsterdam.

Levesque, C. A., and de Cock, A. W. (2004). Molecular phylogeny and taxonomy of the genus. Pythium. Mycol. Res. 108, 1363-1383.

Ling, H. U., and Tyler, P. A. (2000). Australian freshwater algae (exclusive of diatoms). Bibl. Phycol. 105, 1-643.

Lutzoni, F., Kauff, F., Cox, C. J., McLaughlin, D. J., Celio, G., Dentinger, B., Padamsee, M., Hibbett, D. S., James, T. Y., Baloch, E., Grube, M., Reeb, V., Hofstetter, V., Schoch, C., Arnold, A. E., Miadlikowska, J., Spatafora, J., Johnson, D., Hambleton, S., Crockett, M., Shoemaker, R., Sung, G.-H., Luecking, R., Lumbsch, T., O'Donnell, K., Binder, M., Diederich, P., Ertz, D., Gueidan, C., Hansen, K., Harris, R. C., Hosaka, K., Lim, Y.-W., Matheny, B., Nishida, H., Pfister, D., Rogers, J., Rossman, A. Y., Schmitt, I., Sipman, H., Stone, J., Sugiyama, J., Yahr, R., Vilgalys, R. (2004). Assembling the fungal tree of life: progress, classification and evolution of subcellular traits. Am. J. Bot. 91, 1446-1480.

Lynch, M. D. J., and Thorn, R. G. (2006). Diversity of Basidiomycetes in Michigan agricultural soils. Appl. Environ. Microbiol. 72 (11) (in press).

Maggi, O., Persiani, A. M., Casado, M. A., and Pineda, F. D. (2006). Effects of elevation, slope position and livestock exclusion on microfungi isolated from soils of Mediterranean grasslands. Mycologia 97, 984-995.

Martin, F. N. (1992). Pythium. In "Methods for Research on Soilborne Phytopathogenic Fungi" (L. L. Singleton, J. D. Mihail, and C. M. Rush, eds.), pp. 39-49. APS Press, St. Paul.

Martin, G. W., and Alexopoulos, C. J. (1969). "The Myxomycetes." Univ. of Iowa Press, Iowa City.

McLaughlin, D. J., and McLaughlin, E. G. (2001). Preface. In "The Mycota," Vol. VII, "Systematics and Evolution" (D. J. McLaughlin, E. G. McLaughlin, and P. A. Lemke, eds.), Part A, pp. xi-xiv. Springer-Verlag, Berlin.

Mendoza, L., Taylor, J. W., and Ajello, L. (2002). The class Mesomycetozoea: a heterogeneous group of microorganisms at the animal-fungal boundary. Annu. Rev. Microbiol. 56, 315-344.

Metting, B. (1981). The systematics and ecology of soil algae. Bot. Rev. 47, 195-312.

Moncalvo, J. -M., Vilgalys, R., Redhead, S. A., Johnson, J. E., James, T. Y., Aime, M. C., Hofstetter, V., Verduin, S. J. W., Larsson, E., Baroni, T. J., Thorn, R. G., Jacobsson, S., Clemencon, H., and Miller, O. K. Jr. (2002). One hundred and seventeen clades of agarics. Mol. Phylogenet. Evol. 23, 357-400.

Morton, J. B., and Benny, G. L. (1990). Revised classification of arbuscular mycorrhizal fungi (Zygomycetes): a new order, Glomales, two new suborders, Glomineae and Gigasporineae, and two new families, Acaulosporaceae and Gigasporaceae, with an emendation of Glomaceae. Mycotaxon 37, 471-491.

Moser, M. (1983). "Keys to Agarics and Boleti: Polyporales, Boletales, Agaricales, Russulales." Roger Phillips, London.

Mueller, G. M., Bills, G. F., and M. S., Foster, eds. (2004). "Biodiversity of Fungi: Inventory and Monitoring Methods." Elsevier, Amsterdam.

Nash, T. H., ed. (1996). "Lichen Biology." Cambridge Univ. Press, New York.

O'Donnell, K. L. (1979). "Zygomycetes in Culture." Department of Botany, Univ. of Georgia, Athens.

Palmer, J. D., Soltis, D. E., and Chase, M. W. (2004). The plant tree of life: an overview and some points of view. Am. J. Bot. 91, 1437-1445.

Pitt, J. I. (1979). "The Genus Penicillium and Its Teleomorphic States Eupenicillium and Talaromyces." Academic Press, London.

Pugh, G. J. F. (1974). Terrestrial fungi. In "Biology of Plant Litter Decomposition" (C. H. Dickinson, and G. J. F. Pugh, eds.), Vol. 2, pp. 303-336. Academic Press, London.

Raper, K. B. (1984). "The Dictyostelids." Princeton Univ. Press, Princeton, NJ.

Rayner, A. D. M., and Boddy, L. (1988). "Fungal Decomposition of Wood: Its Biology and Ecology." Wiley, Chichester.

Rillig, M. C. (2004). Arbuscular mycorrhizae, glomalin, and soil aggregation. Can. J. Soil Sci. 84, 355-363.

Roberts, P. (1999). "Rhizoctonia-Forming Fungi: a Taxonomic Guide." Royal Botanic Gardens, Kew, UK.

Schadt, C. W., Martin, A. P., Lipson, D. A., and Schmidt, S. K. (2003). Seasonal dynamics of previously unknown fungal lineages in tundra soils. Science 301, 1359-1361.

Schuessler, A., Schwarzott, D., and Walker, C. (2001). A new fungal phylum, the Glomeromycota: phylogeny and evolution. Mycol. Res. 105, 1413-1421.

Seifert, K. A., and Gams, W. (2001). The taxonomy of anamorphic fungi. In "The Mycota," Vol. VII, "Systematics and Evolution" (D. J. McLaughlin, E. G. McLaughlin, and P. A. Lemke, eds.), Part A, pp. 307-348. Springer-Verlag, Berlin.

Smith, S. E., and Read, D. J. (1997). "Mycorrhizal Symbiosis." 2nd ed. Academic Press, San Diego.

Sparrow, F. K. (1960). "Aquatic Phycomycetes." Univ. of Michigan Press, Ann Arbor.

Stalpers, J. A. (1993). "The Aphyllophoraceous Fungi," I, "Keys to the Species of the Thelephorales." Centraalbureau voor Schimmelcultures, Baarn, The Netherlands.

Stalpers, J. A. (1996). "The Aphyllophoraceous Fungi," II, "Keys to the Species of the Hericiales." Centraalbureau voor Schimmelcultures, Baarn, The Netherlands.

States, J. S., and Christensen, M. (2001). Fungi associated with biological soil crusts in desert grasslands of Utah and Wyoming. Mycologia 93, 432-439.

Stephenson, S. L., and Stempen, H. (1994). "Myxomycetes: a Handbook of Slime Molds." Timber Press, Portland, OR.

Swofford, D. L. (2002). "PAUP*: Phylogenetic Analysis Using Parsimony (*and Other Methods)." Version 4. Sinauer, Sunderland, MA.

Tainter, F. H. (1996). "Principles of Forest Pathology." Wiley, New York.

Thorn, R. G. (2002). Soil fungi: nature's nutritional network. In "Encyclopedia of Environmental Microbiology" (G. Bitton, ed.), pp. 2910-2918. Wiley, New York.

Thorn, R. G., Reddy, C. A., Harris, D., and Paul, E. A. (1996). Isolation of saprophytic basidiomycetes from soil. Appl. Environ. Microbiol. 62, 4288-4292.

Vandenkoornhuyse, P., Baldauf, S. L., Leyval, C., Straczek, J., and Young, J. P. W. (2002). Extensive fungal diversity in plant roots. Science 295, 2051.

Venter, J. C., Remington, K., Heidelberg, J. F., Halpern, A. A., Rusch, D., Eisen, J. A., Wu, D., Paulsen, I., Nelson, K. E., Nelson, W., Fouts, D. E., Levy, S., Knap, A. H., Lomas, M. W., Nealson, K., White, O., Peterson, J., Hoffman, J., Parsons, R., Baden-Tillson, H., Pfannkoch, C., Rogers, Y.-H., and Smith, H. O. (2004). Environmental genome shotgun sequencing of the Sargasso Sea. Science 304, 66-74.

von Arx, J. A. (1981). "The Genera of Fungi Sporulating in Pure Culture." J. Cramer, Lehre.

Warcup, J. H. 1950. The soil plate method for isolation of fungi from soil. Nature 166, 117-118.

Wardle, D. A. (2002). "Communities and Ecosystems: Linking the Aboveground and Belowground Components." Princeton Univ. Press, Princeton, NJ.

Wehr, J. D., and Sheath, R. G. (2003). "Freshwater Algae of North America: Ecology and Classification." Academic Press, New York.

West, N. E. (1990). Structure and function of microphytic soil crusts in wildland ecosystems of arid to semi-arid regions. Adv. Ecol. Res. 20, 179-223.

Wright, S. F., and Upadhyaya, A. (1998). A survey of soils for aggregate stability and glomalin, a glycoprotein produced by hyphae of arbuscular mycorrhizal fungi. Plant Soil 198, 97-107.

Zackrisson, O., DeLuca, T. H., Nilsson, M.-C., Sellstedt, A., and Berglund, L. M. (2004). Nitrogen fixation increases with successional age in boreal forests. Ecology 85, 3327-3334.

Growing Soilless

Growing Soilless

This is an easy-to-follow, step-by-step guide to growing organic, healthy vegetable, herbs and house plants without soil. Clearly illustrated with black and white line drawings, the book covers every aspect of home hydroponic gardening.

Get My Free Ebook


Post a comment