Consequences Of Global Environmental Change

The effects of global environmental change, including climate change, UV-B radiation, atmospheric and terrestrial pollutants and genetic engineering, on fungi were considered in detail in Frankland et al. (1996). In the final section of this chapter we highlight some of the issues pertaining to the effects of current predicted climate change on Basidiomycota and, in particular, on the interactions between these fungi and invertebrates.

With increased frequency of summer drought, damage caused by Armillaria spp. is expected to become more prevalent (Rishbeth, 1982; Wargo, 1984). Other Basidiomycota that are dispersed, in some way or another, by invertebrate vectors (see examples above) may see this expansion expedited by the effects of climate. For many invertebrates, particularly insects, geographic ranges are determined largely by climate, while their behaviour, activity and to a large extent abundance are determined by weather variations. Changes in dispersal, migration and distribution patterns may have major consequences.

Invertebrates may exhibit considerable selectivity in their diet preference (Setala et al., 2005). Changes in invertebrate community composition will cascade onto lower trophic levels changing patterns of dominance and composition. Jones et al. (1998), in a study in the Ecotron controlled environment facility at Silwood Park (Lawton, 1996), found that the species composition of a springtail (Collembola) community responded strongly to elevated atmospheric carbon dioxide (CO2). One species, P. minuta, dominated communities at present day

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Proportion in soil community

Figure 3 Effect of elevated CO2 on communities of collembola in soil. Composition of the collembola community at the end (9 months) of ecotron experiments is shown. Microcosm communities were established in soil that was relatively poor in nutrients; They consisted of primary producers, herbivores, secondary consumers (parasitoids) and soil micro- and macroorganisms. All chambers were initiated with the same community; equal densities of each of the five collembola species. For further details see Jones et al. (1998). Data (mean + SEM) from ambient (~350 ppm; open bars) and elevated (ambient+200 ppm; stippled) CO2; n — 8 for each treatment. Pa, Pseudosinella alba; Sp, Sphaeridia pumilis; Pm, Proisotoma minuta; Pra, Protaphorura armata; Fc, Folosmia candida.

CO2 concentrations, while another, F. candida, dominated when the carbon dioxide concentration was increased (Figure 3). This change in Collembola populations coincided with differences in the species of soil fungi present in the microcosm (in this experiment mainly Ascomycota). Fungal decomposers of cellulose were present at higher biomass in the elevated CO2 treatments. Only 14 of the 33 species isolated were common to both treatments, whereas 9 and 10 species, respectively, were restricted to present day and elevated CO2 treatments, a pattern unlikely to occur by chance alone. Elevated CO2 in this study appeared to have major effects on the fungal and springtail soil decomposer components of the food chain. The results were very similar in a Swiss grassland study using a Free-Air CO2 Enrichment (FACE) facility (Jones et al., 2000). No comparable study has been carried out centred on Basidiomycota but with the degree of invertebrate grazing known to occur it would seem that increases in CO2, and other associated changes, will undoubtedly modify biotic community composition.

The yellow dunes, where marram grass (Ammophila arenaria) is more or less completely dominant, are characterized by a group of saprotrophic fungi able to thrive at this early stage of succession. They appear to be confined to sand dunes and to require continuous input of newly deposited sand, often using marram or buried rabbit dung as a resource. They are rarely or never found inland. Species include Psathyrella ammophila, Phallus hadriani and the rare taxa Coprinus ammophilae and Hohenbuehelia culmicola (Rotheroe, 1996). Yellow dune, along with dune slack, are the two low lying habitats most likely to be affected by rising sea-levels in Britain; as well as losing rare fungal communities associated invertebrate populations may also decline.

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