Breeding increases the efficacy of Chondrostereum purpureum in the sprout control of birch.

We tested whether the pairing of selected isolates could be used to increase the efficiency of a decay fungus Chondrostereum purpureum (Pers. Ex Fr.) Pouzar to control hardwood sprouting in Finland. We paired C. purpureum strains efficient in sprout control or highly active in laccase production, and tested the efficacy of their progeny in spout control experiments. This procedure resulted in a strain with an efficacy superior to that of the parental strains. The mortality of birch (Betula pendula Roth. and B. pubescens Ehrh.) 1 cm in stump diameter was 78%, 56% and 9% for the best progeny, the best parental strain and the control, respectively. Mortality was only slightly higher for B. pendula than for B. pubescens but no significant differences were found between the number or maximum height of stump sprouts. Our results showed that cross breeding of this decay fungus is a good alternative in attempts to produce efficient biocontrol agents against hardwood sprouting.

The seeds quality of Betula pndula Roth and Betula oscura Kotula from semi-natural and anthropogenic habitats.

This research presents the results of the study of seeds quality of two Polish native species of the genus Betula L. (Betula pendula Roth and Betula obscura Kotula), growing on the semi-natural (low human activities) and anthropogenic (high human activities) habitats. In this study the generative phase has been investigated to find differences between studied taxa and try to find out why population of B. obscura is very rare. In this research we have checked the quality of the seeds from B. obscura and B. pendula and test the survival of seedlings sowed into the ground researched in laboratory conditions. Results of germination capacity shown significant difference between trees from the anthropogenic and semi-natural sites; the energy capacity indicated significant difference between trees: B. pendula and B. obscura from all study areas. Mixed-model ANOVA/MANOVA for seedlings growth showed statistically important effects of factors (species, area, months). The results show that B. obscura grows better on the anthropogenic habitats than B. pendula, but the latter had more of the fully developed seeds and higher germination and seeds energy capacity.

Impacts of elevated atmospheric CO2 and O3 on paper birch (Betula papyrifera): reproductive fitness.

Atmospheric CO2 and tropospheric O3 are rising in many regions of the world. Little is known about how these two commonly co-occurring gases will affect reproductive fitness of important forest tree species. Here, we report on the long-term effects of CO2 and O3 for paper birch seedlings exposed for nearly their entire life history at the Aspen FACE (Free Air Carbon Dioxide Enrichment) site in Rhinelander, WI. Elevated CO2 increased both male and female flower production, while elevated O3 increased female flower production compared to trees in control rings. Interestingly, very little flowering has yet occurred in combined treatment. Elevated CO2 had significant positive effect on birch catkin size, weight, and germination success rate (elevated CO2 increased germination rate of birch by 110% compared to ambient CO2 concentrations, decreased seedling mortality by 73%, increased seed weight by 17%, increased root length by 59%, and root-to-shoot ratio was significantly decreased, all at 3 weeks after germination), while the opposite was true of elevated O3 (elevated O3 decreased the germination rate of birch by 62%, decreased seed weight by 25%, and increased root length by 15%). Under elevated CO2, plant dry mass increased by 9 and 78% at the end of 3 and 14 weeks, respectively. Also, the root and shoot lengths, as well as the biomass of the seedlings, were increased for seeds produced under elevated CO2, while the reverse was true for seedlings from seeds produced under the elevated O3. Similar trends in treatment differences were observed in seed characteristics, germination, and seedling development for seeds collected in both 2004 and 2005. Our results suggest that elevated CO2 and O3 can dramatically affect flowering, seed production, and seed quality of paper birch, affecting reproductive fitness of this species.