Comparative analysis of genetic diversity in Norway spruce (Picea abies) clonal seed orchards and seed stands

Norway spruce, Picea abies (L.) Karst. is the most important conifer species in Romania and the most planted tree species in the Carpathian Mountains. Here we compare the genetic diversity of four Norway spruce clonal seed orchards and two seed stands located in the Eastern Carpathians. A set of highly polymorphic nuclear microsatellite markers was used. The analysis of genotypic identity of ramets for each Norway spruce clone in all seed orchards indicated that nearly all sampled ramets (97%) were genetically identical. The genetic diversity in seed orchards (He=0.700) was slightly smaller compared to the seed stands (He=0.718). Allelic richness was higher in seed stands (10.874), compared to clonal seed orchards (8.941). The Bayesian analysis indicated a genetic structure with two clusters, one corresponding to the clonal seed orchards and a second one consisting of the two seed stands. Our results provide valuable information for the management of Norway spruce seed orchards in Romania.

Post-fire early successional vegetation buffers surface microclimate and increases survival of planted conifer seedlings in the Southwestern United States

Climate change and fire-exclusion have increased the flammability of western United States forests, leading to forest cover loss when wildfires occur under severe weather conditions. Increasingly large high-severity burn patches limit natural regeneration because of dispersal distance, increasing the chance of conversion to non-forest. Post-fire planting can overcome dispersal limitations, yet warmer and drier post-fire conditions can still reduce survival. We examined how two shrub species with different structures affect below-shrub microclimate and survival rates of planted tree seedlings (Pinus ponderosa, P. edulis, P. strobiformis, Pseudotsuga menziesii) following a high-severity fire in northern New Mexico. We expected that Gambel oak (Querus gambelii), with its denser canopy, would buffer below-shrub climate causing higher survival rates of planted seedlings more than the lower canopy density New Mexico locust (Robinia neomexicana). Seedlings planted under Gambel oak had survival rates 10% to 35% greater than those planted under New Mexico locust. Higher light availability beneath New Mexico locust corresponded to higher temperatures, lower humidity, and higher vapor pressure deficit, impacting the mortality of planted tree seedlings. These results indicate that by waiting for post-fire shrub establishment, selective use of shrubs can buffer microclimate and increase post-fire planting success in the southwestern United States.

Yield table for selected black locust (Robinia pseudoacacia L.) cultivars

In Hungary, the black locust (Robinia pseudoacacia L.) can be considered as the most important fast-growing, stand-forming introduced tree species. Due to its positive growing technological characteristics as well as wood utilization possibilities, at the present, black locust is the most widely planted tree species in Hungary, covering 25% of the country’s total forest area. One of the important tasks ahead of Hungarian black locust growers is to improve the quality of black locust stands with introducing selected cultivars. For the estimation of the growth rate and yield a numerical yield table has been constructed on the basis of surveys of the experimental plots established in pure,managed ’Nyirségi’ ,’Üllői’ and ’Jászkiséri’ black locust cultivars’ plantations which can be suitable for sawlogs production. In the course of 56 stand surveys the key stand characteristics were measured, and then, were reconsidered the average height, diameter (DBH), volume, basal area and stem number given separately for the main (remaining), secondary (removal) and total stands per hectare. The programmable editing procedure allows to extention and formal change of information content of the yield table according to different demands.

Growing Energy Conservation Through Residential Shade Tree Planting

Urban residential shade trees extenuate the heating of buildings in the summertime by intercepting insolation and by evapotranspirative cooling of their immediate surroundings. By modifying location-specific climate data, and tree growth characteristics, this research adapts the Sacramento Municipal Utility District’s (SMUD) Tree Benefits Estimator for application in Toronto, Canada. This tool is then put to use modeling the energy conservation savings delivered by 577 trees planted in Toronto backyards between 1997 and 2000. This study’s results estimate that the trees contributed 77,139 kWh of electricity savings as of 2009, 54.4% of which was due to shading of neighbouring houses. This study’s findings indicate that urban residential tree planting programs should not focus exclusively on location-driven strategic planting to yield large energy conservation benefits. Instead, it is argued that priority should be given to selecting planting locations that will maximize tree survival as neighbourhood energy conservation benefits of a tree that achieves mature stature often outweigh the homeowner-specific benefit of a strategically planted tree.

Growing Energy Conservation Through Residential Shade Tree Planting

Urban residential shade trees extenuate the heating of buildings in the summertime by intercepting insolation and by evapotranspirative cooling of their immediate surroundings. By modifying location-specific climate data, and tree growth characteristics, this research adapts the Sacramento Municipal Utility District’s (SMUD) Tree Benefits Estimator for application in Toronto, Canada. This tool is then put to use modeling the energy conservation savings delivered by 577 trees planted in Toronto backyards between 1997 and 2000. This study’s results estimate that the trees contributed 77,139 kWh of electricity savings as of 2009, 54.4% of which was due to shading of neighbouring houses. This study’s findings indicate that urban residential tree planting programs should not focus exclusively on location-driven strategic planting to yield large energy conservation benefits. Instead, it is argued that priority should be given to selecting planting locations that will maximize tree survival as neighbourhood energy conservation benefits of a tree that achieves mature stature often outweigh the homeowner-specific benefit of a strategically planted tree.

Eucalyptus tereticornis (forest red gum).

Eucalyptus tereticornis is a versatile, fast growing and widely planted tree species. It has been especially successful in areas with summer rainfall followed by a moderate to severe dry season, although fast-growing provenances adapted to a winter rainfall are also available from its extensive natural distribution. The species is marginally less drought tolerant than its close relative E. camaldulensis but appears to be less susceptible than this species to leaf pathogens and stem cankers when planted in areas of seasonally-high humidity. Provenances have been identified from the southern, temperate part of the species distribution that are moderately frost and salt tolerant. Eucalyptus tereticornis is proving a valuable partner in various hydrid combinations with other fast growing eucalypts, including E. grandis and E. urophylla. The wood is used for a wide range of purposes including fuel, charcoal, paper, poles, posts, mining timber, hardboard and particleboard while the tree is used for shelterbelts, shade and in apiculture.

Exploring the potential of two-aged white spruce plantations for the production of sawlog volume with simulations using SORTIE-ND

The main objective for even-aged plantation (EAP) management of producing sawlog material has driven practices towards low initial planting densities and lower post thinning densities. For semi-shade tolerant species, the resulting stand density potentially leaves enough growing space for the introduction of a second cohort of trees in the understory, making it a two-aged plantation (TAP). TAP could have many silvicultural benefits, especially in sensitive areas where intensive treatments associated with EAP are incompatible with local management objectives. White spruce (Picea glauca) is a good candidate species for modeling TAP because it is the most widely planted tree species in Canada and has proven tolerance to understory planting. SORTIE-ND, a single-tree spatially explicit growth model was used to explore the yield of variable density and rotation length scenarios when each white spruce cohort is introduced mid rotation, compared to traditional even-aged management. All TAP scenarios tested produced more sawlog volume and more merchantable volume than equivalent densities of EAPs. The lowest density tested, 400 stems ha-1 planted every 35 years, had the highest sawlog yields (3.23 m3 ha-1 yr-1). Considering smaller size products changes the optimum TAP scenario but maintains the advantage over EAPs.