MICROCALORIMETRIC INVESTIGATIONS OF MICROBIAL ACTIVITIES - DECOMPOSITION OF NEEDLE LITTER UNDER LABORATORY CONDITIONS

Microcalorimetric experiments on litter degradation included in a forestal amelioration program are reported. Abolition of water limitation in needle litter induced a strong initial peak in heat evolution. This transitory activation is due to easily degradable substrates utilized equally well by fungi and bacteria as shown by the addition of selective inhibitors. Degradation proceeded in three phases of changing activity depending on individual additives (lime, ammonium chloride, cellulose). Addition of cellulose alone stimulated degradation while nitrogen supply had no significant effect. Addition of lime always reduced the degradation rate. Particularly in combination with nitrogen addition, lime strongly inhibited the microbial activity by a release of ammonia, total weight loss after seven months being also reduced. No physical reactions were found interfering with true metabolic heat production, thus proving the validity of the method.