Ectomycorrhizal trees

The growth of ectomycorrhizal trees is frequently improved by their increased phosphorus (P) accumulation (3), and this, in turn, is related to the intensity of the mycorrhizal infection. Ectomycorrhizal fungi solubilize insoluble forms of A1 and Ca phosphates as well as inositol hexaphosphates, though a wide interstrain variability has been recorded (112). These complex P forms are digested by the secretion of extracellular acid and alkaline phosphomono- and phosphodi-ester-ases. Pi in soil solutions is easily taken up by ectomycorrhizal hyphae and then translocated to the host roots. Its absorption and efflux are probably regulated... 

Blum et al. (2002) and Probst et al. (2000) have found, in areas similarly cation-depleted by acid deposition, that a considerable proportion of calcium released by weathering came from apatite dissolution. This apatite was utilized directly by ectomycorrhizal tree species (spruce and fir) bypassing the soil exchange complex. In the Blum et al. (2002) study, ectomycorrhizal fungi associated with the roots of conifers provided 95% of the calcium found in the foliage of the trees and 35% of the Ca leaving the mixed conifer hardwood watershed in stream water. 

Eeckhaoudt S, Vandeputte D, Van Praag H, et al. 1992. Laser microprobe mass analysis (LAMMA) of aluminum and lead in fine roots and their ectomycorrhizal mantles of Norway spruce (picea abies (1.) karst.). Tree Physiol 10 209-215. 

Ahonen-Jonnarth, U., Goransson, A. Finlay, R. D. (2003). Growth and nutrient uptake of ectomycorrhizal Finus sylvestris seedlings treated with elevated A1 concentrations. Tree Physiology, 23, 157-67. 

Leake, J. R., Donnelly, D. P., Saunders, E. M., Boddy, L. Read, D. J. (2001). Rates and quantities of carbon flux to ectomycorrhizal mycelium following C pulse labeling of Pinus sylvestris seedlings effects of litter patches and interaction with a wood-decomposer fungus. Tree Physiology, 21, 71-82. 

Colpaert, J., van Laere, A. van Assche, J. A. (1996). Carbon and nitrogen allocation in ectomycorrhizal and non-mycorrhizal Pinus sylvestris L. seedlings. Tree... 

Perez-Moreno, J. Read, D. J. (2000). Mobilization and transfer of nutrients from litter to tree seedlings via the vegetative mycelium of ectomycorrhizal plants. New Phytologist, 145, 301-9. 

This chapter reviews the distribution, mechanism and impact of mineral tunnelling by soil ectomycorrhizal fungi (EMF). Most trees in boreal forests live in close relation with EMF (Smith Read, 1997). These EMF mediate nutrient uptake they form an extension of the tree roots. In turn they obtain carbohydrates from the tree. Over the years ectomycorrhizal (EM) research has a strong focus on nutrient acquisition by EMF from organic sources (Read, 1991). In boreal forest systems, however, minerals could also be an important nutrient source, especially for calcium, potassium and phosphorus (Likens et al, 1994, 1998 Blum et al, 2002). Recent developments in EM research suppose a role for EMF in mobilizing nutrients from minerals (see Wallander, Chapter 14, this volume). 

Fransson, P. M. A., Taylor, A. F. S. Finlay, R. D. (2000). Effects of continuous optimal fertilization on belowground ectomycorrhizal community structure in a Norway spruce forest. Tree Physiology, 20, 599-606. 

Cline, E.T., J.F. Ammirati and R.L. Edmonds. 2005. Does proximity to mature trees influence ectomycorrhizal fungus communities of Douglas-fir seedlings New Phytologist 166 993-1009. 

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