Thesis (Ph. D.)--Swedish University of Agricultural Sciences, 1999. / Includes bibliographical references.

Continental scale analysis of the savanna biome indicated that fire did not spread at tree canopy cover above 40%. This study investigates this relationship in a field study. It is possible that the type of tree (forest vs. savanna) may influence the amount of shade experienced by the understory and therefore this study also explores differences in LAI between congeneric pairs of forest and savanna tree species. Data were collected in two major South African savanna parks. Plots were set out to measure grass biomass in reference to canopy cover in both Kruger National Park (n=60) and the Hluhluwe-iMfolozi Game Reserve (n=82). Seven congeneric pairs were selected to compare leaf area and LAI between forest and savanna tree species using a destructive method. Against expectations, it was only when canopy cover reached 80% that grass fuel load was too low to support fire spread in all Kruger National Park plots (Pr=O) and 89% of the Hluhluwe-iMfolozi Game Reserve plots (Pr=0.11). No consistent, general relationships were evident with leaf area or LAI in comparisons between forest-savanna congeneric pairs. The significance of these findings and future direction is discussed.

Thesis deals with renewables resources, potential of biomass and plants phytomass. We focused on the cultivation of selected energy crops, as perennial grasses Elymus elongatus (subsp. ponticus, cv. Szarvasi-1), reed canary grass, miscanthus sinensis and annual crops of maize and sorghum. The practical part is aimed to the establishment of small plot trials with a variety Szarvasi-1, reed canary grass and miscanthus. We described the methods of field experiment establishing with crop Szarvasi-1 of their treatment and harvest. The results of our own experiments we compared with the literature data. The last part deals with the economy of growing selected crops.