Search

Highlights • Novel exotic tree species bring elevated economic, biosecurity and ecological risks. • Limited exotic introduction is justified to fulfil specific commercial objectives. • There is no justification for novel exotic introduction for conservation objectives. • Exotic introduction requires comprehensive risk assessment across forestry sectors. Abstract Both plantation forests and native woodlands are currently facing challenges in the form of rapid climatic change and unprecedented increases in damage by exotic pests and diseases. To combat these problems it has been proposed that a range of novel exotic tree species (non-native species that have not yet undergone thorough operational testing or previously been grown at a forestry scale) should be grown as part of an adaptive management strategy, and that non-native (including novel) species should be introduced into native woodland. Justifications for this policy are that novel exotic species are required to maintain forest productivity under climate change, to create a more diverse, and by implication more resilient forest, and to substitute for native species threatened by introduced pests and pathogens. Here we examine these arguments in the context of British forestry, where there is a long history of utilising non-native species. On the basis of this documented experience we conclude that in the commercial sector of British forestry, where production is the main objective, there are strong arguments for undertaking a programme of rigorous testing and domestication of a very limited number of the most promising novel exotics which, in addition to good timber and growth, also have attributes that will allow the development of more naturalistic silvicultural systems and a move away from current clear-fell regimes. However this must be undertaken within a comprehensive risk assessment framework, where candidate species are rigorously screened both for any biosecurity threats, and their potential for causing ecological damage if they become invasive outside their initial planting sites. Widespread planting of candidate species should only be recommended after the completion of full species and provenance trials, and when reliable sources of appropriately adapted seed have been established. Conversely where conservation of biodiversity is an objective we find no support for introduction of any non-native species. This is based on the greater ecological and economic risk they pose compared to the use of native species. Use of non-natives is likely to lead to an increase rather than a decrease in pest and disease problems, and to hinder rather than support the retention of threatened native tree species and their associated biodiversity. [ABSTRACT FROM AUTHOR]

Integrated Pest Management (IPM) offers a suite of ways by which to reduce the need for pesticide use, thus minimising environmental damage and pathogen resistance build-up in crop production. Farmers and agronomists active in the Scottish spring barley sector were surveyed to determine the extent to which they currently use or are open to implementing three IPM measures – varietal disease resistance, crop rotation, and forecasting disease pressure – in order to control three important fungal diseases. Overall, the survey results demonstrate that farmers and agronomists are open to using the three IPM techniques. However, gaps between actual and perceived recent practice were large: despite over 60% of farmers stating that they sowed varieties highly resistant to Rhynchosporium or Ramularia, less than one third of reportedly sown varieties were highly resistant to these diseases. Similarly, over 80% of farmers indicated that they used crop rotations, yet 66% of farmers also reported sowing consecutive barley often/always. Further research is needed in order to understand why these gaps exist, and how they can be reduced in future in order to increase IPM uptake and optimise pesticide use. [ABSTRACT FROM AUTHOR]

In recent years, numerous articles have addressed management strategies aimed at assisting forests to adapt to climate change. However, these seldom take into account the practical and economic implications of implementing these strategies, notably, supply of forest plants and seed. Using semi-structured interviews with practitioners involved in the plant and seed supply chain in Great Britain, we highlight a series of practical and economic bottlenecks commonly encountered in the supply of locally sourced seed and domestically produced planting stock for native woodland and hedging markets. We find that adoption of alternative seed sourcing strategies, designed specifically to account for directional climate warming, is likely to exacerbate existing problems by adding further complexity to decisions nurseries make about tree species and seed origins to produce. The lack of long-term market predictability brought about by the current configuration of forestry grants and regulations and, in particular, the administrative systems for processing grant applications is identified as a major impediment to having a sustainable and competitive supply of home-grown and currently adapted planting stock. Finally, the time and effort it takes to supply healthy plants for native woodland creation projects deserves much wider recognition throughout the industry and will be crucial if planting objectives are to be met sustainably. [ABSTRACT FROM AUTHOR]

Abstract: Environment-driven genetic differentiation among populations is a common feature among forest trees, and an understanding of how populations have adapted to their home site conditions is essential for management and conservation practices. In Scotland, 84 native Scots pine (Pinus sylvestris L.) woodlands are recognised by the Forestry Commission and they occupy highly diverse environments from the maritime west coast to continental sites in eastern Scotland. However, it is not known whether adaptations to local environments along sharp temperature and rainfall gradients have occurred in different populations and as a result, the seed transfer guidelines of the species are based only on data from isozymes and monoterpenes. In this study of an outdoor common-garden trial, we used chlorophyll fluorescence to examine whether seedlings from 32 open-pollinated families and eight populations from sites experiencing contrasting annual temperature regimes differed in their response to variation in natural outdoor temperatures between September 2009 and May 2010. In addition, growth initiation in spring was recorded. Photochemical capacity at photosystem II Fv/Fm showed a distinct seasonal trend and remained at relatively high levels (∼0.7) until November. Following a period of over 2weeks with temperatures below or close to 0°C, Fv/Fm started decreasing towards its minimum values recorded in early March when population means varied between 0.35 and 0.45. By early May and along with rising temperatures, photochemical capacity had recovered to the same level as observed in early November. Populations were found to respond differently to the cold period starting in December. The largest drop in photochemical capacity was observed in seedlings from a low-altitude population located in the maritime western Scotland, while in seedlings from higher-altitude locations in the cooler eastern Scotland, the response was smaller. In March, the recovery of photochemical capacity was slowest in seedlings from the mildest and coolest sites. Evidence of adaptive genetic differentiation was also found in spring phenology. Initiation of shoot elongation and needle flush were earlier in families from higher altitudes (cooler areas), but population differences were not significant at the α =0.05 level. These results suggest that adaptation to the spatially heterogeneous environment in Scotland has taken place in Scots pine and that in order to minimise the risk of planting maladapted seed stock, the patterns of environmental and adaptive genetic variation should be taken into account in the management of genetic resources in this species. [Copyright &y& Elsevier]

Forest restoration programmes aim to use material for re-planting that is genetically diverse and not inbred. However, restricted seed sampling, high variance in reproductive output, and the production of inbred seeds that survive in the nursery but not in the wild can lead to forest restoration stock being genetically compromised. The aim of this study was to evaluate whether the reproductive biology of the New Caledonian endemic conifer Araucaria nemorosa makes it susceptible to these genetic problems and to assess whether there is evidence for genetic bottlenecks and elevated inbreeding in nursery stock compared to seedlings and adults from wild source populations. Reproductive output was low with high variance among trees (only 14% of adult trees surveyed produced mature cones, >50% of examined cones had <10 viable seeds). Evidence for an extreme genetic bottleneck was detected in a nursery population established from cones collected from adult trees. A second nursery population established with seed collected from the forest floor showed no evidence of a genetic bottleneck, but was inbred compared to its wild source population. In light of these results, we do not recommend collecting cones directly from A. nemorosa as an efficient means of establishing genetically diverse stock for restoration programmes. Collecting seed from the forest floor is likely to be more effective, but the planting stock may contain a high proportion of inbred individuals. Collecting established wild seedlings already subjected to natural selection is suggested as an alternative method of maximising the diversity captured, whilst minimising sampling effort and proportion of inbred individuals. [Copyright &y& Elsevier]

Traditional species-based conservation programmes are appropriate in situations where species are readily identifiable. However, in certain taxonomically complex groups of organisms, generally characterized by the presence of uniparental lineages and reticulate evolution, it is not possible to classify biodiversity into discrete and unambiguous species. Attempts to impose species-based conservation on such taxonomically complex groups are proving untenable, and threaten to divert scarce resources and taxonomic expertise from the conservation of other priority groups. We argue here that a new approach should be adopted for taxonomically complex groups. We advocate the conservation of evolutionary processes that generate taxonomic biodiversity, rather than the preservation of a limited number of poorly defined taxa arising from this evolution. [Copyright &y& Elsevier]

The development of strategies for in situ, ex situ conservation and reforestation of the monkey puzzle tree (Araucaria araucana), a vulnerable tree endemic to southern South America, has led to an interest in the level and distribution of the genetic diversity of the species. Neutral DNA markers (RAPDs) and quantitative genetic techniques were used to characterise genetic heterogeneity within and among populations from throughout the natural range of the species. Both the level and pattern of genetic variation estimated using the different techniques were essentially uncorrelated. An important discrepancy was found with the neutral markers failing to detect an important quantitative genetic divergence across the Andean Range relating to drought tolerance. This study clearly demonstrates the potential problems associated with making recommendations for conserving the genetic resource of threatened species based solely on neutral marker studies. Alternative approaches are discussed, including a stronger focus on ecologically important traits and the potential use of surrogate measures of genetic variability. [Copyright &y& Elsevier]

Evaluates pathogenic consequences of introducing lodgepole pine in Sweden. Risk posed by the introduction of lodgepole pine to native forests; Concern regarding the possibility of evolution of aggressive population of native Scots pine pathogens on highly stressed lodgepole pine plantations; Impact of introduction of lodgepole pine pathogen in Sweden on native Scott pine and lodgepole pine growing as an exotic.

Studies the ecological effects and management aspects of an exotic North American lodgepole pine tree Pinus contorta in Sweden. Area covered by the lodgepole pine tree plantation in Sweden; Suggestion on management of the plantations of these species to minimize the harmful effects of their introduction on ecosystem; Strategy to observe the adverse effects from the plantations for better Pinus contorta management.

Whole genome resequencing of 25 isolates of the ascomycete pine pathogen Dothistroma septosporum revealed the presence of three genetically distinct races in Scotland, confirming previous results based on microsatellite markers. The genetically uniform indigenous race from Scotland (NPR), is closely related to an introduced and genetically diverse southern race (SR) from England and France. Race LPR, confined to lodgepole pine, is genetically divergent from these, but has close affinity with Canadian (CAN) isolates. Genome comparisons between individuals within CAN and SR races revealed short and scattered regions of near sequence identity, indicating significant sexual reproduction. Sequence identity patterns within LPR suggest that it derives from introduction of a single sexual fruit body from North America. Finally a first generation interracial hybrid between indigenous NPR and introduced SR was identified, signalling an increase in the evolutionary potential of D. septosporum in Scotland, and an enhanced risk to native Scots pine (Pinus sylvestris). • Whole genome resequencing reveals three Dothistroma septosporum races in Scotland. • Indigenous race NPR is asexually reproducing with very low genetic diversity. • Introduced race SR practices some sexual reproduction and is genetically diverse. • Race LP introduced from North America is probably derived from a single ascocarp. • Hybridisation has occurred between races NPR and SR within native Scots pinewoods. [ABSTRACT FROM AUTHOR]

• Canopy leaf angle from vertical increased in landraces with latitude of origin. • Northern European landraces reach canopy closure before Southern European landraces. • Chlorophyll content varied significantly between the landraces unrelated to climate. Improving the efficiency of photosynthesis is a potential strategy for increasing crop yields in the future, but this is only possible if genetic variation exists for this attribute within crop germplasm resources. A key component of photosynthetic efficiency is the plant's ability to intercept light. This study examined the extent of genetic variation, available within barley landraces from Europe, for parameters affecting light interception. Landraces varied in time spent between emergence and full canopy establishment, with those from Northern latitudes reaching canopy closure between 2 and 8 days faster than those from Southern latitudes. There was significant variation in leaf chlorophyll content between the landraces, but this was unrelated to site of origin. Landraces originating from locations with cooler temperature over the growing season held their leaves in a more planophile manner than those from warmer climates, resulting in a negative relationship between leaf angle and mean temperature at site of origin. We conclude that substantial genetic variation in key parameters affecting light interception have evolved among barley landraces in Europe that could be utilised in future breeding programmes to improve the efficiency of photosynthesis and increase crop yields. [ABSTRACT FROM AUTHOR]

The multi-locus phylogenetic species recognition approach and population genetic analysis of Amplified Fragment Length Polymorphism (AFLP) markers were used to delineate Lophodermium taxa inhabiting needles of Scots pine ( Pinus sylvestris ) in native pinewoods within Scotland. These analyses revealed three major lineages corresponding to the morphological species Lophodermium seditiosum and Lophodermium conigenum , fruiting on broken branches, and Lophodermium pinastri , fruiting on naturally fallen needles. Within L. pinastri three well supported sister clades were found representing cryptic taxa designated L. pinastri I, L. pinastri II, and L. pinastri III. Significant differences in mean growth rate in culture were found among the cryptic taxa. Taxon-specific primers based on ITS sequences were designed and used to classify over 500 Lophodermium isolates, derived from fallen needles of P. sylvestris in three Scottish and one French pinewood site, into the three L. pinastri cryptic taxa. Highly significant differences in the relative abundance of the three taxa were found among the Scottish pinewood sites, and between the French and all of the Scottish sites. [ABSTRACT FROM AUTHOR]

Self-incompatible species with restricted seed and pollen flow are considered the most vulnerable to the deleterious genetic effects of habitat fragmentation. Immediate effects of fragmentation are expected to be loss of allelic diversity and differentiation of fragments by genetic drift. Later, loss of S allele diversity may lead to restricted mate availability, increased relatedness of genotypes within patches, accelerated loss of genetic diversity and eventual loss of capacity for seed production. We studied the self-incompatible clonal shrub Linnaea borealis within the Cairngorms National Park, Scotland, whose pinewood habitat has been fragmented for an extensive period, possibly millennia. Exhaustive sampling revealed 123 patches (median length 15 m), 91% of which were further than the maximum pollen flow distance from their nearest neighbours (30 m). Using ten microsatellite markers, only 21% of the patches produced more than one multilocus genotype. Individual genotypes extended from 1 to 74 m. Bayesian clustering of the 179 multilocus genotypes revealed six clusters. One cluster occupied a geographically distinct area where seed production still occurs and showed significant genetic differentiation from (F st = 0.164, P < 0.01) and significantly lower allelic richness (A R = 4.0 vs A R = 7.0 P < 0.01) than the remainder of the sample set. Spatial genetic structure in the total sample set indicated significant relatedness of clones within the first 1.5 km. Overall, L. borealis in Scotland seems to be experiencing extreme genetic effects of chronic population fragmentation with only 16% of patches having the capacity for seed production. Genetic rescue is being undertaken by transplanting unrelated clones from > 1.5 km distance into extant monoclonal patches. [ABSTRACT FROM AUTHOR]

Abstract: Rare and threatened subarctic willow scrub communities in the UK are the subject of ongoing conservation programmes, yet little is known about the diversity of fungal taxa that they support. Isolates of the rust genus Melampsora were sampled from 112 leaves of eight subarctic willow (Salix) taxa and their hybrids from twelve sites in the UK. In order to determine the number of Melampsora taxa present in the samples, isolates were sequenced for the Internal Transcribed Spacer (ITS) region of rDNA and data were subject to phylogenetic analysis. Maximum likelihood and Bayesian analysis indicated that the isolates fell into three strongly supported host-associated clades. Clade I contained only isolates from Salix herbacea and was distinguished morphologically by dense urediniospore echinulation and thin cell walls. Clade II contained isolates from Salix arbuscula and Salix reticulata only. These could not be distinguished morphologically from isolates in Clade III which were found on Salix lapponum, Salix myrsinites, Salix myrsinifolia, Salix aurita, Salix lanata, and their hybrids. Clade II was most distinct in ITS sequence, differing by 50 bases from Clades I and III, while the latter clades differed in sequence by only 24 bases on average. Clades I and III are likely to represent the previously recognised taxa Melampsora alpina Juel 1894 and Melampsora epitea Thüm. 1879 respectively, but Clade II has not apparently been described before. Significant differences in the intensity of infection by isolates of Clade III were found among different Salix species at a single site, suggesting either differences in resistance among Salix taxa, or the presence of further cryptic taxa within Clade III. The study illustrates the power of molecular phylogenetic analysis to reveal cryptic biodiversity within Melampsora, and suggests that conserving Salix host diversity within subarctic willow communities will ensure that a diversity of associated Melampsora taxa is maintained. [Copyright &y& Elsevier]