Whereas there is evidence that mixed-species approaches to production forestry in general can provide positive outcomes relative to monocultures, it is less clear to what extent multiple benefits can be derived from specific mixed-species alternatives. To provide such insights requires evaluations of an encompassing suite of ecosystem services, biodiversity, and forest management considerations provided by specific mixtures and monocultures within a region. Here, we conduct such an assessment in Sweden by contrasting even-aged Norway spruce (Piceaabies)-dominated stands, with mixed-species stands of spruce and birch (Betula pendula or B. pubescens), or spruce and Scots pine (Pinussylvestris). By synthesizing the available evidence, we identify positive outcomes from mixtures including increased biodiversity, water quality, esthetic and recreational values, as well as reduced stand vulnerability to pest and pathogen damage. However, some uncertainties and risks were projected to increase, highlighting the importance of conducting comprehensive interdisciplinary evaluations when assessing the pros and cons of mixtures.

The rotation length is a key component of even-aged forest management systems. Using Fennoscandian forestry as a case, we review the socio-ecological implications of modifying rotation lengths relative to current practice by evaluating effects on a range of ecosystem services and on biodiversity conservation. The effects of shortening rotations on provisioning services are expected to be mostly negative to neutral (e.g. production of wood, bilberries, reindeer forage), while those of extending rotations would be more varied. Shortening rotations may help limit damage by some of today’s major damaging agents (e.g. root rot, cambium-feeding insects), but may also increase other damage types (e.g. regeneration pests) and impede climate mitigation. Supporting (water, soil nutrients) and cultural (aesthetics, cultural heritage) ecosystem services would generally be affected negatively by shortened rotations and positively by extended rotations, as would most biodiversity indicators. Several effect modifiers, such as changes to thinning regimes, could alter these patterns.

Because of the limited spatial extent and comprehensiveness of protected areas, an increasing emphasis is being placed on conserving habitats which promote biodiversity within production forest. For this reason, alternative silvicultural programs need to be evaluated with respect to their implications for forest biodiversity, especially if these programs are likely to be adopted. Here we simulated the effect of varied rotation length and associated thinning regimes on habitat availability in Scots pine and Norway spruce production forests, with high and low productivity. Shorter rotation lengths reduced the contribution made by production trees (trees grown for industrial use) to the availability of key habitat features, while concurrently increasing the contribution from retention trees. The contribution of production trees to habitat features was larger for high productivity sites, than for low productivity sites. We conclude that shortened rotation lengths result in losses of the availability of habitat features that are key for biodiversity conservation and that increased retention practices may only partially compensate for this. Ensuring that conservation efforts better reflect the inherent variation in stand rotation lengths would help improve the maintenance of key forest habitats in production forests.

Genetic parameters were estimated for traits observed in one short-term "farm-field" test and in seven long-term field trials of Norway spruce (Picea abies (L.) Karst.). The trials, located in southern and central Sweden, were based on subsets of 201 open-pollinated families derived from plus trees grafted in seed orchards. Observations of height growth and phenology in the farm-field test were made during years 2-4, and trees in field trials were assessed for height and damage at 9-14 years of age. Narrrow-sense heritabilities for height-growth traits in the field trials varied from 0.05 to 0.47. Heritabilities in the farm-field test were approximately 0.80 for date of bud burst, 0.35 for leader lignification, and 0.20 for frequency of seedlings with free growth. Early bud burst and a high degree of free growth in the farm-field test were genetically correlated with lower height and higher frequency of ramicorns and frost damage in the field trials. Height in the farm-field test was poorly and inconsistently correlated with height in the field. Genetic correlations for final heights among the field trials were usually significant and in the range of 0.7 and above. Correlations did not decline with distance between trials, suggesting that local climate is more important than regional climatic zones when matching site and genotype.

A retrospective early test of Picea abies (L.) Karst. was conducted under two temperature ("high" and "low") and two irrigation ("well-watered" and "drought") regimes. Height, dry mass, and phenological traits were assessed for seedlings from 36 open-pollinated families grown in a growth chamber for two growth periods. The attributes measured were compared with the growth traits of three 24-year-old field progeny trials propagated from the same parents. Heritabilities for biomass and height were mainly moderate to strong (0.1–0.8) in the well-watered treatments, while they were weaker in the drought treatments (0.0–0.5). Juvenile-mature (J–M) genetic correlations for growth traits were generally weak. There were, on average, stronger J–M correlations in the drought treatments than in the well-watered treatments. Similarly, there were stronger J–M correlations in the high- than in the low-temperature treatment. The results suggest that genotype × environment (G×E) interaction between the juvenile and mature environment is one of the reasons for low J–M correlations. This supports the hypothesis that higher J–M correlations can be obtained by mimicking natural growth-limiting factors in the juveniles' growth chambers. We conclude that further development of more efficient early selection methods for P. abies should include periodic drought and the development of optimal temperature regimes.