Vc

spectrometry, real-time microscale (100 X 100 mm) multichanges in leaf surface carbohydrate chemistry caused by fungal colonization are beginning to be revealed. It has yet to be shown how this can be scaled up to ecosystem scales and related to nutrient cycling.

In addition to the changes in fungal species during colonization of a resource unit (leaf, twig, branch, etc.) the dominant fungal species in communities can be a function of the dominant type of resource entering the decomposition system. During seral succession of vegetation from herbaceous to forest ecosystems, there is a change in dominant plant species and plant form (Heal and Dighton, 1986). Along with this change in plant form, there is a general change in the diversity and complexity of resources entering the decomposer system. The initial seral stages are marked by an addition of high-quality resources to the decomposer community, consisting mainly of cellulose and a high C:N ratio and a low lignin content. Following forest canopy closure, woody resources and more recalcitrant leaf litters dominate (Attiwill and Adams, 1993). These litters have high lignin content and low C:N ratios, and therefore decompose at a slower rate. In addition to changes in the dominance of the fungal species or group with ecosystem succession, the degree of interaction between fungi and animals increases. There are more and more intimate associations between fungi and fauna in the exploitation of the more recalcitrant plant residues (Table 2.15).

In forested systems, much deadwood remains in the canopy prior to recruitment to the forest floor. This standing dead material may have a different fungal community than wood on the forest floor. The work of Boddy and Rayner (1983) on oak wood in canopies showed that 12 basidiomycete fungal species dominated in the community. Of these, Phellinus ferreus, Sterium gausapatum, and Vuilleminia comendens were pioneer species of partially living branches, Phlebia adiata and Coriolus versicolor were secondary colonizers, and Hyphoderma setigerum and Sterium hirsutum were related to insect activity. In wood, the interactions among fungi can be most clearly observed. The zones of interaction among adjacent, competing fungal colonies have been mapped in three dimensions using wood as a resource (Rayner, 1978; Rayner and Boddy, 1988). Clear demarcation zones are set up when genetically incompatible strains or species meet in a relatively homogenous resource. In an environment in which resources are patchily distributed, such as mixed litter on the forest floor, the colonization of individual resource units is more difficult to map. The colonization pattern of individual straw resource units by a range of fungal species was correlated to relative growth rates of the fungi on agar (Robinson et al., 1993a). These rates of growth allowed four species to be ranked in combative order. Mixtures of fungal species caused significant reductions in the rate of growth of less combative fungal species in the presence of combative species. The cascade of decomposition is thus related to colonization of u

Table 2.15 Changes in Plant Forms, Their Residues, the Dominant Fungal Groups Effecting Plant Litter Decomposition and the b.

Interactions Between Fungi and Animals During Plant Serai Succession from Herbaceous Ground Cover to High Forest 7

Table 2.15 Changes in Plant Forms, Their Residues, the Dominant Fungal Groups Effecting Plant Litter Decomposition and the b.

Interactions Between Fungi and Animals During Plant Serai Succession from Herbaceous Ground Cover to High Forest 7

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