Bacteria made up an average of 90 per cent of the microbial populations of twenty-four soil samples, mainly of the &H horizon, from four peat-podzol transitions. Bacillus spp., which averaged 67 per cent of these bacteria, were usually the predominant group. Gram-negative non-spore-forming organisms (I 5 per cent), Streptomyces (8 per cent), and Gram-positive cocci (5 per cent) occurred irregularly and Arthrobacter and Nocardia strains rarely. A large proportion of the strains utilized glucose and malate, and a smaller proportion starch, citrate, and protein. A few strains liquefied pectin but none decomposed cellulose or xylan. In eight populations examined, 80 per cent of the bacteria required yeast extract for growth. Fungi usually formed only a small proportion of the populations. All the species, except Penicillium nigricans and Trichodermu viride, were isolated from only one transition. Yeasts occurred irregularly, usually in small numbers. Whilst no microbial group responded to the addition of glucose, nitrate, and phosphate to two soil samples, bacterial numbers increased after the addition of peptone and yeast extract.
A study of growth rings in relatively fast-grown rimu trees from terrace forest in south Westland revealed a number with conspicuously dark latewood bands. These have been called marker rings. The regular occurrence of these marker rings in the same sequence in a number of trees indicates that growth rings are formed contemporaneously in all relatively fast growing trees. A good correlation between the occurrence of marker rings and cool autumn temperatures in the years in which they were formed is very strong evidence that the rings are formed annuaIly. Discontinuous false rings were found in some fast-grown trees. but continuous false rings were not discovered. Discontinuous growth rings were found in strongly fluted trees. in leaning trees. and in very slow-growing trees. No evidence of missing rings was found. but it is possible that growth rings could be absent from slow-growing tree'!. * Stationed at Forest apd Range Experiment Station, Rangiora.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.