Growth and Silvicultural Potentiality of Lomatia hirsuta Forests from Stump Shoots in the Valley of El Manso/Patagonia/Argentina

Lomatia hirsuta (Lam.) Diels is a pioneer tree species that regenerates mostly after fire and is more frequently found as a secondary species in Patagonian forests dominated by Austrocedrus chilensis and Nothofagus dombeyi. However, in the El Manso Valley, Province of Río Negro in Western Argentina, L. hirsuta forms pure stands, originated from stump shoots. The wood is very attractive for its colourful appearance and beautiful grain, suitable for fine furniture. Nevertheless, these forests are not managed for timber production, they are mostly thinned for grazing, and the wood is mainly used as firewood. The objective of this study was to evaluate the possibility to improve quality wood production in stands through silvicultural interventions in a sustainable way. Samples have been carried out in dense stands of different ages and in one less dense stand with the traditional use for pastures. We evaluated the state and quality of the trees, and their growth has been studied by means of trunk analysis. The results indicate that there is a significant potential to improve the production of quality wood in dense stands through thinning oriented to crop trees. This should start in young stands, because in older stands, good form and sound trees are already considerably reduced. It also became apparent that forest management is necessary to stabilize these nearly unattended forests, which in old stands are very vulnerable to damages caused by wind and wet snow. In such stands, the extraction of trees could be combined with the planting of seed trees, with the expectation to improve the quality and vigour of the trees at maturity.

Sitka spruce in Estonia

An overview of introduction of Sitka spruce in Estonia. First reports of cultivation of Sitka spruce in Estonia come from 1879. In 1895, Peravalla forest area (now Järvselja) obtained a small amount of seed from Thüringen. Saplings from that seed were planted in the forest in 1904, but for 1928 all trees were perished. During the 20th century, seed of Sitka spruce from different provenance of the natural distribution area was repeatedly sown and seedlings grown in Järvselja and some other places in Estonia, but all the cultivation attempts failed sooner or later. There are no Sitka spruces remained from the pre-War period in the mainland part of Estonia. In 1984, a group of saplings from seed of 1978 was planted in Järvselja. These trees are 15 m mean height with 20.6 cm mean diameter now. In 1975, a small group of large Sitka spruces was found growing in a remote forest park of Suuremõisa Manor, island of Hiiumaa. These Sitka spruces were revisited by us in spring 2018, to measure the trees and determine their age by tree rings. Nine trees out of 13 bigger spruces were cored. Age of the trees exceeded nearly 120 years. The planting time coincides with work period of Karl Ahrens, the forest officer of Suuremõisa Manor at that time. In spring 2018, the mean diameter at breast height (DBH) of the tree group was 62 cm and mean height ca 36 m. The biggest tree had DBH 101 cm (with 37 m height) while the maximum height for the tree group was 38 m. The Suuremõisa group of Sitka spruces on 0.02 ha is remarkable by its dense stand. If to extrapolate to one hectare, the growing stock of the stand would exceed 3 thousand cubic meters. The vital group of Sitka spruces at Suuremõisa have proved that this foreign tree species can grow rather well in the western islands and coastal region of Estonia. Sitka spruce can grow faster than native Norway spruce in Estonia. Future decades will show the viability of Sitka spruce cultures in the mainland of Estonia.

Impact of postfire management on forest regeneration in a managed hemiboreal forest, Estonia

Fire is a significant agent for the development of boreal and hemiboreal forests, altering soil and light conditions, affecting seedbanks, and removing seed trees. Burned areas should be managed with care, as inappropriate techniques prolong the regeneration period and reduce the diversity and resilience of stands to disturbances. To study the effects of fire and postfire management on the successional changes in regeneration abundance, species composition and tree height sample plots were established in sandy pine forests in northwestern Estonia on areas burned 2 or 22 years ago. Five types of sample plots were established: (i) areas without fire damage, (ii) burned uncleared areas, (iii) burned forest areas cleared after forest fire, (iv) burned uncleared areas with live trees, and (v) burned uncleared areas with dead trees. Three main tree species common to hemiboreal forests were analyzed: Betula spp., Pinus sylvestris L., and Populus tremula L. Results showed that clearing burned areas after wildfire significantly reduced the abundance of regeneration compared with burned uncleared areas but favored height growth of P. sylvestris in later development. To regenerate and maintain mixed stands after wildfire, retaining some residual trees can facilitate regeneration compared with complete clearing, although a dense stand with live trees or a large amount of deadwood can hinder regeneration.

Wheat Landraces Are Better Qualified as Potential Gene Pools at Ultraspaced rather than Densely Grown Conditions

The negative relationship between the yield potential of a genotype and its competitive ability may constitute an obstacle to recognize outstanding genotypes within heterogeneous populations. This issue was investigated by growing six heterogeneous wheat landraces along with a pure-line commercial cultivar under both dense and widely spaced conditions. The performance of two landraces showed a perfect match to the above relationship. Although they lagged behind the cultivar by 64 and 38% at the dense stand, the reverse was true with spaced plants where they succeeded in out-yielding the cultivar by 58 and 73%, respectively. It was concluded that dense stand might undervalue a landrace as potential gene pool in order to apply single-plant selection targeting pure-line cultivars, attributable to inability of plants representing high yielding genotypes to exhibit their capacity due to competitive disadvantage. On the other side, the yield expression of individuals is optimized when density is low enough to preclude interplant competition. Therefore, the latter condition appears ideal to identify the most promising landrace for breeding and subsequently recognize the individuals representing the most outstanding genotypes.

Relationships of grain carbon isotope discrimination (Δ) and ash content with yield and quality in dry bean

SUMMARYDry bean (Phaseolus vulgaris L.) is a traditional crop of north-western Macedonia, Greece, where two landraces (plaki Prespas and Chrisoupoli) in particular are grown. The aim of this study was to test whether the grain carbon isotope discrimination (Δ) and ash content (ASH) are related to grain yield (GY), protein content (PC) and mean grain weight (MGW) in dry bean. As a part of a honeycomb selection programme, 21 genotypes (19 lines derived via intra-landrace honeycomb selection for single plant yield at low density plus the two original populations) were grown at two densities, 1·2 and 4·8 plants/m2 under non-limiting water conditions in a glasshouse and in the field. Genotypes differed significantly for Δ, ASH and PC under the low density. In the dense stand, genotypes differed significantly only for ASH and PC. The environment (glasshouse or field conditions) affected all the traits significantly. Neither Δ nor ASH showed strong or consistent relationships with GY and thus, they cannot serve as reliable, indirect selection criteria for GY. Strong, negative relationships between Δ and PC were found especially in the dense stand, confirming analogous results in C3 cereals. Inconsistent genotypic ranking for grain physiological traits under the different densities and environments was indicative of large genotype×environment interaction. Genotypes performed consistently for GY and MGW under both densities, showing the strong stability of these traits.