Survival and vitality of Gremmeniella abietina on Pinus sylvestris slash in northern Sweden

Survival and vitality of Gremmeniella abietina on Pinus sylvestris slash was studied in northern Sweden during 2003 and 2004. Once a month between September 2003 and April 2004, two to three trees were cut down and debranched. Shoots with pycnidia were sampled at the felling date and then at every consecutive month. The percentage of germinated conidia from each shoot was calculated after 24, 48 and 72 h incubation. The vitality of G. abietina pycnidia in the slash remained high the whole period. Intact pycnidia were found on slash several months after the time of conidial sporulation, which indicates that new pycnidia may be produced on dead pine branches. Sampling of shoots from slash on 13‐ to 18‐month‐old clear‐cuts showed conidial germination capacity as high as in pycnidia collected in fresh slash. Due to survival of G. abietina in slash it is recommended to postpone planting of P. sylvestris seedlings in northern boreal areas to the third vegetation period after sanitary clear‐cuts.     

Gremmeniella-infected Pinus contorta as raw material in the production of kraft pulp

Pinus contorta, logs with occluded cankers caused by the pathogen Gremmeniella abietina, as well as logs from unaffected trees were sampled from a 23-year-old plantation in Sweden and compared in terms of their paper properties. Damaged wood gave kraft pulp with poor paper properties: it required a larger amount of beating energy and resulted in paper with low tear strength, air permeability, tensile stiffness, burst strength, and poor light-scattering properties. However, small amounts of damaged wood mixed in with a large amount of healthy wood can pass almost unnoticed. The use of trees with a larger content of damaged wood will lead to serious processing problems and give a pulp with poor paper properties. Thus, wood damaged by Gremmeniella should be sorted out and classed as low-grade raw material.     

Sugar beet extract induces defence against Phytophthora infestans in potato plants

The aim of this study was to find a natural and cheap agent that could induce defence responses in potato plants to combat Phytophthora infestans, which causes late blight disease that is one of the most devastating plant pathogens in agriculture. We tested whether a sugar beet extract (SBE), derived through a simple extraction procedure from a large-scale plant waste product, induced resistance under green-house conditions. In three potato genotypes differing in their level of resistance to P. infestans (two susceptible genotypes: Desiree and Bintje and one partially resistant: Ovatio), treatment with SBE resulted in significant reduction of the size of the infection lesions in a pattern similar to that seen with application of a known defence-inducing compound, β-aminobutyric acid (BABA). Lower sporangial production was also observed on SBE-treated leaves, but the reduction in sporangial production was more pronounced after BABA treatment. SBE had no apparent toxic effect on the hyphal growth of the pathogen or on the germination of sporangia. Instead, SBE triggered pathogenesis-related protein (PR-1 and PR-2) induction which suggests that the protection conferred by SBE could be via induced resistance. An array of phenolic metabolites was found in the SBE that may contribute to the defence response.     

Does biological quality matter? Direct and reflected appraisal of biodiversity in temperate deciduous broad-leaf forest

Using a multilevel approach, this study investigates direct (perceptual, emotional, and physiological responses [qEEG]) and reflected (preference, attitude, and intention to accept conservation measures) appraisal of different levels of biodiversity in temperate deciduous broad-leaf forest biotopes. Thirty-five participants viewed three series of zoomed pictures from biotopes assessed according to biological criteria to be of High, Intermediate, and Low level of biodiversity. Participants’ appraisal differed between the biotopes, and partly between the conceptualisation of appraisal, but overall there was a consistency across direct and reflected levels of appraisal. The most prominent result of the analysis of qEEG was a higher brain activity in the Theta frequency for the Low biotope. The Theta frequency has amongst others been associated with on-set of sleep and in the present context probably indicating that the Low biotope was less stimulating. The Low biotope was perceived to have the lowest degree of biodiversity followed by the Intermediate and the High biotopes. The Intermediate biotope elicited the most positive emotional response, and was rated highest in preference and in importance to conserve, whereas the intention to accept conservation measures did not differ between the biotopes. Thus biodiversity related criteria presently favoured in forest conservation management schemes are not necessarily prioritised by the public. Emotional components are likely to be at stake tending to favour the conservation of biotopes of an intermediate level of biodiversity.     

Formation and growth of stem cankers caused by Gremmeniella abietina on young Pinus contorta

From 1990 to 1995, the formation and growth of stem cankers caused by Gremmeniella abietina on Pinus contorta var. latifolia was studied in three stands in northern Sweden. The stands were planted in 1976–80. The total number of cankers on 756 trees that were individually followed increased from 233 to 477 during the 5‐year period. With 42.0% of the cankers, the pathogen entered through or from the base of diseased branches, and 33.6% through visually undamaged bark. Most of the cankers were within 100 cm of the ground. In one of the three areas, the cankers were evenly distributed within 180 cm of the ground. The frequency of cankers facing north exceeded those facing south. The average vertical length of cankers had increased, 55.6% of cankers had increased their percentage coverage of the stem girth; 13.8% had fully girdled the stem. At two of the sites, there was a negative correlation between canker coverage of the stem circumference and tree height increment.     

Restoring forests: regeneration and ecosystem function for the future

Conventions and policies for biodiversity conservation and climate change mitigation state the need for increased protection, restoration and climate change adaptation of forests. Much degraded land may be targeted for large-scale forest restoration, yet challenges include costs, a shortage of regeneration material and the need for restored forests to serve as a resource for communities. To ensure ecosystem function for the future, forest restoration programs must: (1) learn from the past; (2) integrate ecological knowledge; (3) advance regeneration techniques and systems; (4) overcome biotic and abiotic disturbances and (5) adapt for future forest landscapes. Historical forest conditions, while site-specific, may help to identify the processes that leave long-term legacies in current forests and to understand tree migration biology/population dynamics and their relationship with climate change. Ecological theory around plant–plant interactions has shown the importance of negative (competition) and positive (facilitation) interactions for restoration, which will become more relevant with increasing drought due to climate change. Selective animal browsing influences plant–plant interactions and challenges restoration efforts to establish species-rich forests; an integrated approach is needed to simultaneously manage ungulate populations, landscape carrying capacity and browse-tolerant regeneration. A deeper understanding of limiting factors that affect plant establishment will facilitate nursery and site preparation systems to overcome inherent restoration challenges. Severe anthropogenic disturbances connected to global change have created unprecedented pressure on forests, necessitating novel ecological engineering, genetic conservation of tree species and landscape-level approaches that focus on creating functional ecosystems in a cost-effective manner.