Chemical and mineral composition of ectomycorrhizosphere soils of subalpine fir (Abieslasiocarpa (Hook.) Nutt.) in the Ae horizon of a Luvisol

Abstract

L. 1999. Chemical and mineral composition of ectomycorrhizosphere soils of subalpine fir (Abies lasiocarpa (Hook.) Nutt.) in the Ae horizon of a Luvisol. Can. J. Soil Sci. 79: [25][26][27][28][29][30][31][32][33][34][35]. Differences in the properties of bulk forest and rhizosphere soils are often attributed to ectomycorrhizal association, or the symbiosis characterized by a fungal sheath surrounding the root (mantle) and intercellular root colonization (Hartig net). We compared the soil pH, total C, N, cation exchange capacity, and the contents of mica, chlorite, kaolinite, 2:1 expandable clays, feldspars and amorphous materials between two ectomycorrhizosphere soils (or soil environment in the vicinity of ectomycorrhizae (ECM)) and non-ectomycorrhizosphere soils to study the influence of ectomycorrhizae on chemical and mineralogical properties of soils. The two ectomycorrhizosphere soils were characterized by ectomycorrhizal colonization dominated by (1) Piloderma spp., and (2) Mycelium radicis atrovirens and cottony yellow-brown (MRA-CYB) types or where Piloderma spp. colonization was <2%. Our results showed that total C and N were higher in ectomycorrhizosphere than non-ectomycorrhizosphere soils, and the ectomycorrhizosphere soils dominated by Piloderma spp. had almost twice the total C and N as ectomycorrhizosphere soils with MRA-CYB. Soil pH was lower by half a pH unit in ectomycorrhizosphere soils compared to non-ectomycorrhizosphere soils. Cation exchange capacity as well as exchangeable Ca 2+ , Mg 2+ and K + were lower in non-ectomycorrhizosphere soil compared to ectomycorrhizosphere soils. We also found that cation exchange capacity, exchangeable Ca 2+ , Mg 2+ and K + values in soils dominated by Piloderma spp. were higher compared to ectomycorrhizosphere soils with insignificant Piloderma spp. Our results suggest that transformation rate of mica and chlorite to 2:1 expandable clays was predominant in ectomycorrhizosphere compared to non-ectomycorrhizosphere soils, likely as a result of high production of organic acids and direct extraction of K + and Mg 2+ by fungal hyphae. In ectomycorrhizoplane samples, it is suggested that K + and possibly amorphous Al 2 O 3 and Fe 2 O 3 could reconstitute the degraded mica and chlorite through the formation of hydroxy-interlayered 2:1 clays. Soil properties and biogeochemical processes in bulk forest soils are often different from those of the rhizosphere or the narrow soil environment affected by activities of living roots (Foster et al. 1983;Curl and Truelove 1986

Properties of soils influenced by ectomycorrhizal fungi in hybrid spruce [Picea glauca × engelmannii (Moench.) Voss]

“…This is similar to findings on subalpine fir (A. lasiocarpa) ECM (Arocena et al 1999) but is in contrast to other studies that report Piloderma ECM to be confined to organic materials (Brand 1991;Goodman et al 1996). The functional role of Piloderma ECM associations is largely unknown but reports suggest that ECM may be involved in granite weathering (Jongmans et al 1997).…”

“…Cenococcum geophilum ECM occurred at low to moderate levels in ECS soils and the abundance was similar to the findings of Arocena et al (1999) for rhizosphere root samples of subalpine fir. Reports suggest that it occurs between the forest floor and mineral soil in some forests in British Columbia (Harniman and Durall 1996;Hagerman et al 1999;Mah et al 2001;Khetmalas et al 2002).…”

“…Other ECM such as S. variegatus on P. sylvestris seedlings reportedly enhanced the uptake of K more from biotite than microcline (Wallander and Wickman 1999). Calcium-rich encrustations on Piloderma hyphae might prevent the buildup of toxic levels of calcium and oxalate (Arocena et al 1999(Arocena et al , 2001. Piloderma associates with subalpine fir in the same area where it was found on hybrid spruce; it is possible that it has a similar role in the rhizosphere zones of both tree species.…”

“…In Douglas-fir stands , Cromack Jr. et al (1979) reported a pH 4.9 for soils colonized by H. crassum; this was significantly lower than pH 6.1 measured in uncolonized soil. ECS soils of subalpine fir also had a lower pH than that of N-ECM soils (Arocena et al 1999). Berthelin (1983) attributed the low pH in the mycorrhizosphere zone to oxidized inorganics (e.g., sulphur) and the production of organic acids (e.g., oxalic, carbonic, citric, acetic) by the activities of ECM.…”

“…Arocena et al (1999) indicated that fungi (and other organisms) in the ECS were significant sinks for carbon assimilated by the host plant; upon death, their biomass may contribute to the high contents of total C and N in ECS soils. For example, Suillus luteus (a mycorrhizal fungus) could utilize up to 30% of the total C assimilated by P. sylvestris (Söderström and Read 1987), while Douglas-fir potentially allocates up to 73% of assimilated C to ECM (Fogel and Hunt 1983).…”