Fungal communities : relation to resource succession

An example of substrate succession: the colonization of pine needles by fungus flora Perhaps the most widely studied substrate succession was the successive development of fungal strains and other decomposer organisms at the inside of pine needles, from tree foliage to humified litter. Using litter bags and moist chamber cultures, Kendrick & Burges (1962) followed the fate of Scots pine needles (Pinus sylvestris L.) in the course of seasons and years and recognized several well-marked steps in the fungal succession. Their study was exemplary inasmuch as they displaced studies on fungal successions from the field of mycology to that of soil ecology. From their results, it appeared that needles, as leaves (Kinkel et al. 1987), were small temporary islands, the inhabitants of which evolved together with their habitat both in space (vertical litter transfer) and time (season, year), while internal resources became progressively depleted. This scheme was reminiscent of patterns and processes observed in the successional development of plant communities by Watt (1947). Other authors described similar sequences in other pine species, pointing on the worldwide occurrence of a few number of more or less pine-specific fungal colonizers succeeding each other in a linear way (Watson et al. 1974, Mitchell & Millar 1978a, Soma & Saitô 1979). Other interesting results of pine studies were that the course of fungal succession was strongly influenced by i) the start of colonization when the needle was still living (Mitchell et al. 1976, 2 Mitchell and Millar 1978b), iii) climate (Van Maanen et al. 2000, Gourbière et al. 2001), but did not seem to be affected by surface grazing of the needles (McLean et al. 1996). A more complete pattern, including penetration of pine needles by mycorrhizal fungi and soil micro-and mesofauna, was scrutinizing successive layers within a small surface of Scots pine litter (5x5 cm). The succession of organisms, both microbial and animal, which took place in pine needles, from death of foliage to disappearance in humus, was summarized in Figure 1, taking into account numerous possible shortcuts which were found to occur currently. It should be highlighted that all organisms involved in this successional course mineralized organic matter, through excretory as well as respiratory pathways. In the course of this successional process, which can be considered at first sight as a processing chain sensu Heard (1994), the substrate was observed to change, as long as resources were exploited by successive inhabitants of …