Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Polish Journal of Ecology

2 2006

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Response of silver birch (Betula pendula Roth.) seedlings to experimental variation in aluminum concentration

Bojarczuk Krystyna, Oleksyn Jacek, Karolewski Piotr, Żytkowiak Roma

Polish Journal of Ecology

2006

Vol. 54, nr 2

189-200

The process of soil degradation and destabilization of forest ecosystem by industrial pollution is frequently associated with mobilization of toxic. Al^3+ ions. Both these processes exert a negative influence on tree root systems and may even result in the decline of whole forest stands. One-year-old seedlings of silver birch (Betula pendula Roth.) grown in pots were treated with a range of aluminum sulfate concentrations in order to test the effects of Al on growth, root structure, content of phenolic compounds and mineral nutrition of roots and foliage. Plants exposed to Al concentrations exceeding 50 mg Al dm^-3 had reduced growth, root structure and a substantial increase of Al concentration occurred in foliafe and roots. Concentration of several elements in the foliage and roots declined with increasing Al concentration, including Mg and Ca , and to a lesser extent, P, K, and Na. Most root traits such as root mass or root growth rate were more strongly affected by Al than the foliage. Changes in root Ca, Al and Ca:Al ratio, and root morphology were detected at the lowest Al concentration (50 mg Al dm^-3) indicating usefulness of these traits as early indicators of adverse aluminum effects on plants.

Differences in defence strategies against herbivores between two pioneer tree pecies: Alnus glutinosa (L.) Gaertn. and Betula pendula Roth.

Giertych Marian J., Karolewski Piotr, Żytkowiak Roma, Oleksyn Jacek

Polish Journal of Ecology

2006

Vol. 54, nr 2

181-187

The different defence strategies of trees against herbivores are very often connected with succession status, leaf life span and the level of secondary metabolites. We examined the effect of simulated leaf grazing on the differences in the leaf life span and defence chemistry of two pioneer tree species that belongs to the same family (Betulaceae), black alder (Alnus glutinosa (L.) Gaertn.) and European white birch (Betula pendula Roth.). At the beginning of the growing season, mature leaves were perforated using a paper punch. The holes removed about 10% of the leaf surface. Each species was represented by six trees - one branch was chosen for perforation and one branch as a control. All leaves were counted every week until their abscission. Additional damages caused by grazing insects were also noted.Undamaged birch leaves were held much longer than those of alder. The average difference in half leaf life span between control and perforated leaves was 28 days in birch and 6 in alder. The control unperforated alder leaves were significantly (P <0.05) more often grazed by insects than those that were perforated. Leaf perforation in alder increase phenolic concentrations in the new, young leaves. In birch we did not observe these changes.The comparison of alder and birch indicate that the species with similar successional status can have different strategies of leaf defence. The birch leaves were characterized by a longer leaf life span, constitutive defence, a lack of induced defence accumulation of phenolics and earlier shedding of damaged leaves in comparison to the control. The black alder foliage had a shorter leaf life span, induced defence reaction (producedmore phenolics after perforation), and only slightly earlier shedding of damaged leaves than the control.