Experiments were set up to assess the relative impacts of grass lamina fragment density, size and quality on the
activity and growth of four fungi in a particulate soil-like matrix. The fungi studied were Cladosporium
cladosporioides, Fusarium lateritium, Phoma exigua and Trichoderma viride, all of which are common inhabitants
of UK upland grassland soils. Resource quality was varied by using three contrasting grasses as sources of lamina
fragments: Lolium perenne, Agrostis capillaris and Nardus stricta. All the fungi were able to forage effectively
through the soil-like matrix (at a rate of 1–2 ml matrix d−1) and colonize and partially decompose available lamina
fragments (up to 40% d. wt loss). Foraging rates (ml matrix d−1) were affected by lamina fragment species but not
by fragment density or size. In general, F. lateritium and T. viride foraged at a faster rate than the other species.
Mycelial activity in the soil-like matrix was directly proportional to total lamina fragment availability and was
unaffected by fragment size. Biomass production on solid media was also directly related to substrate
(carbohydrate) availability. The results indicate that these fungi can adjust their growth patterns in response to
fragment density so as to maximize foraging efficiency (energy acquired per unit exploratory biomass production).
Differences in lamina fragment species were responsible for up to 50% reduction in mycelial activity.