L'evoluzione della cerchia legnosa in Quercus Pubescens W. Ein Quercus Ilex L. nel clima di Firenze

Summary

The evolution of the wood ring in Quercus pubescens W. and in Quercus Ilex L. in Florence (from June 1946 to June 1947).

The present study deals with the anatomical characters of the wood ring of Q. pubescens and of Q. Ilex. In both the specimens the wood of the stem and of the young branch has been investigated.

In both plants studied the cambial tissue of the stem starts dividing at the end of April, reaching its maximum activity from May to June.

On the contrary the cambium of the branch differentiates in Q. pubescens a month earlier (18 March-18 April) than in Q. Ilex (18 April-18 May). While in the branch of Q. Ilex a false ring can be seen corresponding to the autumn months, nothing of the kind is found in the branch of Q. pubescens; though it presents a false ring in the stem.

It is difficult to date clearly the period when the cambium stops its activity, but probably it happens at the end of August in the samples of the stem.

The leaf buds of Q. pubescens and of Q. Ilex open during April-May and the young branch is completely developed at the end of June. In both oaks some buds open in autumn, but the small branches are prevented to develop because of the cold.

No comparison can be made between the opening of the buds and the beginning of the cambial activity in the stem and in the branch.

Considering the evolution of these woods and their relationship to climatic factors, we can see that the cambial activity starts during a period of remarkable rainfall and of regular increase of temperature, and stops almost completely at the end of July, when temperature and dryness reach their highest values.

The autumn rainfall would favour again a cambial activity, but the values of the temperature, regularly decreasing, do not allow it.     

Ricerche biochimiche,biofisiche e istochimiche intorno al problema della metacromasia

Con 10 Figure in bianco-nero e 5 a colori nel TestoIl presente lavoro è stato eseguito usufruendo in parte anche di un contributo del Consiglio Nazionale delle Ricerche.     

Arbutus unedo L. communities in southern Iberian Peninsula mountains

Arbutus unedo L. communities in the southern part of the Iberian Peninsula (Spain and Portugal) were studied, highlighting the differences regarding their floristic composition, biological diversity and plant dynamics according to the dominant geological substratum. Firstly, this type of formation on the little-known decarbonated calcareous substrata was analysed using classification techniques. Later, they were compared to the remaining phytocoenoses in the southern part of the Iberian Peninsula using an ordination analysis. As a result, a new suballiance is proposed together with two plant associations, which will enable us to characterize the strawberry tree groves growing on carbonated substrata and those already proposed for siliceous substrata are confirmed.     

Tommaso Saivadori's Ornithologia della Papuasia e delle Molucche, Vol. II

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