Long-term dynamics of leaf and root decomposition and nitrogen release in a grey alder (Alnus incana (L.) Moench) and silver birch (Betula pendula Roth.) stands

The decomposition of the leaf litter, fine roots (d?<?2?mm) and coarser roots (2?≤?d?<?5?mm) of grey alder and silver birch, as well as of α-cellulose sheets using the litterbag method was studied in two experimental stands on Podzoluvisol soils in Southern Estonia. For both tree species, the coarser roots decomposed faster than the fine roots, (p?<?.05), tree species did not affect the decomposition rate of the roots (p?>?.5). The nitrogen (N) input to soil from aboveground litter was multiple times higher than the N flux from roots. The remaining relative ash-free mass of the leaves of grey alder and silver birch after three and a half years was similar. After 11 years the remaining relative ash-free mass of the fine and coarser roots of grey alder still accounted for around 10% of the initial value. For silver birch the remaining value was around 20% after 9 years. The litterbag method to underestimates in fertile soils the decomposition of organic matter and thus did not reflect the actual dynamics of decomposition.     

Histological Investigation of Pelvic Symphysis in Holstein-Friesian Cattle

Knowledge of the changes in cattle pelvic symphysis during gestation and obstetrics gives valuable information about the age of optimal primary calving of cows. The aim of the study was to investigate the histological changes of pelvic symphysis in Estonian Holstein-Frisian＇s （EHF） of different ages. Eight EHF cows up to five years of their age were divided into three age groups： calved, in-calved and after calved bovines. Material for histological and histochemical investigation was taken from four places： （1） cranial part ofpubic bone; （2） pubo-ischiadic junction; （3） symphyseal eminence; （4） body of the interischiadic bone. In all study-groups, the cranial part of pubic bone consisted of cartilage. In pubo-ischiadic junction of calves connective tissue proper, fibrous and hyaline cartilage were noted. In in-calved cattle with gestation of 4-5 months and in after calved cattle group hyaline cartilage and bone tissue were noted, however in in-calved cattle with gestation of 7.5 months fibrous cartilage and connective tissue proper prevalated. In sympyseal eminence of calves connective cartilage osseous tissue was present. The region of interischiadic tissue proper and cartilage were noted; in other groups besides bone of calves consisted of connective tissue proper and fibrous cartilage, meanwhile in in-calved and after calved EHF＇s in the region hyaline cartilage and osseous tissue prevalated. These preliminary results demonstrate that the main changes in the pelvic symphysis histology, retardation of ossification, of EHF kines occur during the second-half of gestation in the pubo-ischiadic junction.