Flower and seed production as affected by axis category and shoot size in two Patagonian Nothofagus species

Flower distribution within the tree crown may affect both pollination dynamics and the costs of flowering on tree growth. For Nothofagus obliqua (Mirb.) Oerst. and Nothofagus nervosa (Phil.) Krasser, the production of flowers and viable seeds were compared among axes of contrasting size and category in the tree crown. For annual shoots arising from three axis categories (main branches, secondary branches, and twigs), the numbers of nodes, staminate flowers, pistillate flowers and axillary buds, and seed viability were evaluated. Most flowering shoots produced both staminate and pistillate flowers. The number of flowers of each type was related positively with the number of nodes of the shoot. Longer shoots had proportionally more pistillate flowers than short shoots. The three axis categories produced both flower types in direct proportion to the size of their shoots, but main branches presented more axillary vegetative buds than secondary branches and twigs. For N. obliqua, the percentage of viable seeds was lower in secondary branches than in main branches and twigs, perhaps owing to a lower probability of cross-pollination in secondary branches. The coexistence of vegetative and reproductive functions may cause interference between them. Massive allocation of meristems to flowering reduces meristem availability for growth and, especially, flowering in the following growing season.

Effects of aspect and type of competition on the early performance of Nothofagus dombeyi and Nothofagus nervosa in a mixed plantation

In the Andes of Chile, two valuable Nothofagus tree species coexist (Nothofagus dombeyi (Mirb.) Oerst. and Nothofagus nervosa (Phil.) Krasser). They could provide an opportunity for mixed plantations because of their ecological differences. In a mixed plantation with a checkerboard design on a good site where the two species naturally coexist, we evaluated their performance according to aspect and type of competition. Nothofagus dombeyi had a greater survivorship (90% vs. 65%) and growth (twice in diameter and 20% greater in height). Forking was significantly lower in N. nervosa (23% vs. 70%). Aspect did not significantly affect the performance of N. dombeyi. The north aspect had a significant negative effect on survivorship of N. nervosa, but aspect did not significantly affect growth or forking of this species. The aspect – type of competition interaction was only significant for N. nervosa in diameter and marginally significant in height. The checkerboard design allowed for a clear separation of interspecific and intraspecific competition in this mixed plantation. Interspecific competition favored growth of N. nervosa on the north aspect (facilitation) and was detrimental to N. nervosa on the south aspect (competition). These results have a direct application when planting mixtures of species of complementary ecological characteristics that can increase the value of the plantation.

Lachancea nothofagi sp. nov., a yeast associated with Nothofagus species in Patagonia, Argentina

Six strains of a novel yeast species were isolated from Nothofagus species trees in native forests in Patagonia, Argentina. The strains were isolated from bark, fluxes and the ectomycorrhizospheric soil fraction of Nothofagus antarctica, Nothofagus nervosa and Nothofagus pumilio. Analysis of the D1/D2 large-subunit rDNA sequences indicated that the novel species belonged to the genus Lachancea and is closely related to Lachancea meyersii. The name Lachancea nothofagi sp. nov. is proposed to accommodate these strains. The type strain is UWOPS 99-807.3T (=CBS 11611T=NRRL Y-48670T).