The objective of this study was to compare the utility of combinations of data from airborne laser scanning (ALS), RapidEye satellite imagery and auxiliary environmental data to predict stand structure in a plantation forest. Both parametric and non-parametric modelling techniques that could simultaneously predict a multivariate response were employed and found to produce predictions with similar levels of accuracy. Response variables were derived from 463 field measurement plots that were used during model development; a further 60 randomly selected plots were set aside for validation of model performance. Candidate predictor variables were extracted from the ALS data, satellite data and auxiliary environmental data, and the variables with the greatest explanatory power were used to create six separate models based on combinations of the data sources. Model validation showed that models using RapidEye data only were the least precise and that adding auxiliary environmental data only led to a moderate improvement in model precision. The model precision observed was similar to those reported previously from studies using satellite data to predict stand structure. Models developed using data from ALS were by far the most precise and adding information from satellite data or auxiliary environmental data led to negligible improvement in the prediction of stand structure. Although the outputs of both model types were similar, the practical efficiencies of using the non-parametric approach make it appealing to meet the demands of managers of industrial plantation forest managers.

We studied biophysical (biotic and abiotic) factors correlating with dominant height and basal area (BA) development within 110 ha of evergreen mixed conifer forest dominated by coast redwood (Sequoia sempervirens (D. Don) Endl.) in north coastal California. Various descriptors of species composition, topography, soil properties and moisture, light and harvest disturbance were assessed in a grid of 234 permanent sample plots. Within the study area characterized by heterogeneous topography and variable species composition, site descriptors alone were poor predictors of stand volume production in multiple linear regressions. Multivariate canonical correlation analysis revealed that redwood height growth was related to a different suite of biophysical variables than BA growth. Greater stand volume production was measured in areas with less hardwood, more Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirbel) Franco), higher soil pH and at lower slope positions. Sheltered lower slopes were more amenable to redwood height growth. Exposed upper slopes and ridges receiving more light favoured BA over height growth in redwood. Our analysis provides a framework for refining estimates of forest growth, yield and carbon stocks in natural forests in accordance with divergent dimensions of productivity and allied biophysical gradients.

Norway spruce (Picea abies (L.) Karst.) understory seedlings, growing in partially harvested plots with different canopy cover in a boreal spruce stand, were spot fertilized (Hydro 15-4-12) 9 years after planting. The principal aim was to test the hypothesis that nitrogen (N) availability influences growth of understory seedlings at intermediate but not at low levels of irradiance. In addition, we tested the combined influences of N and light availability on selected morphological and phenological traits, covering a 2-year period after treatment. Diffuse radiation (DIFR) at the seedling level was estimated from hemispherical photographs and ranged from 19 to 46 per cent of DIFR in open conditions. Fertilizer application was associated with a marked increase in foliar N concentration. The fertilized seedlings grew better in height and root collar diameter compared with unfertilized controls. While the absolute growth in both diameter and height increased with increasing DIFR, seedlings also responded to improved nutrient availability across the range of light conditions studied. Fertilizer treatment did not affect the number of nodal buds, but we observed a higher apical dominance ratio and advanced bud burst in fertilized seedlings. In conclusion, nutrient availability influenced growth and bud phenology of understory Norway spruce seedlings at least down to 20 per cent DIFR.

Megaplatypus mutatus (syn. Platypus sulcatus) is an ambrosia beetle native to South America, which represents the main forest pest in Argentina of Poplar plantations and is also an emerging pest in Europe, representing a potential risk to forest and fruit plantations globally due to its low specificity. Knowledge of the interactions this insect has with microbes will be important in understanding its impacts and management. In this study, we characterized the fungal diversity associated with M. mutatus in Populus trees in Argentina. The fungal community of 28 attacked trees was studied by evaluating 1104 gallery fragments and 110 fragments of insects. Fungal isolates were identified using morphology and phylogenetic analysis of the internal transcribed spacer region of nDNA. Nineteen taxa were identified, the most relevant Fusarium solani species complex, three species of Raffaelea and Graphium basitruncatum. Despite the lower frequency occurred by Raffaelea spp. and G. basitruncatum, we detected a specificity between male/female and location in the gallery. Additionally, the topology of the galleries is described based on analyses with computed tomography and nuclear magnetic resonance. Enhancing these techniques, an image combining both data was produced, suggesting that the water circulation across outer sections might be involved in the modulation of the gallery topology.

The structural attributes of an old-growth forest remnant of Pinus nigra subsp. salzmannii located in southern Spain and those from nearby managed forests were compared. Data on environmental and structural variables were collected in 74 forest inventory plots. Significant differences were tested by means of the Mann–Whitney U-test. A partial redundancy analysis was conducted to assess the relative contribution of both environmental and management variables in explaining differences in the current structure of old-growth and managed stands. Additionally, 25 trees of different size (range 25.4–98 cm) and age (67–803 years) were cored and dendrochronological methods and bootstrap linear regression were used to study the effects of size and age on tree growth. The old-growth stand exhibited a higher density of large trees (diameter at breast height >50 cm) and greater variability in tree size than managed stands, but lower tree density and, consequently, similar values of stand basal area and volume. Environmental variables accounted for 5.7 per cent of the total variance observed in structural attributes, while the contrasting silvicultural condition (old-growth vs managed) accounted for 10.2 per cent. Growth, measured in units of stand basal area, increased continuously with tree size.

While there is considerable interest in transforming even-aged stands into species-diverse, irregular structures, the rarity of stands close to the end of the transformation process has resulted in a lack of knowledge on optimum target structures that are considered sustainable. This study examined this problem in a mixed-species selection stand that has undergone transformation for over 60 years. Complete inventories of a one-hectare permanent sample plot were carried out in 2015 and previously in 2009, 2003 and 1997. The diameter distribution remained relatively static with the q factor remaining at 1.4 since the 2009 inventory. An improvement in the number of regenerating seedlings and saplings available for recruitment from previous inventories suggests that the current structure is relatively stable although shade-tolerating conifers are gradually dominating the stand. Not all the sustainability criteria were met; however, the stand could be described as having reached a balanced condition. It is recommended that the current stocking density and basal area (~350 stems ha–1 and 26–27 m2 ha–1, respectively) should be maintained and that future harvesting interventions should aim to reduce the number of large diameter stems (>55 cm DBH), which represent 14 per cent of the stocking but 48 per cent of the stand basal area.

The inclusion of quadratic mean diameter (QMD) and relative spacing index (RSI) substantially improved the predictive capacity of height–diameter at breast height (d.b.h.) and crown ratio models (CR), respectively. Data were obtained from 208 permanent plots established in western Arkansas and eastern Oklahoma during 1985–1987 and remeasured for the sixth time (2012–2014). Existing height–d.b.h. and CR estimation models for naturally occurring shortleaf pine forests (Pinus echinata Mill.) were updated and modified for improved performance. Additionally, eight height–d.b.h. relationship models that use only d.b.h. (fundamental local models) were modified using covariates. The model performance was evaluated using fit statistics [root mean square error (RMSE), Fit index and Akaike information criteria (AIC)]. The results showed that the best model form which was an extended non-linear model with autoregressive first order AR (1) structure and power variance function performed better than extended mixed-effects models and predicted well as an ordinary least squares non-linear model. The autocorrelation within individual trees was larger for the height–d.b.h. relationship than for CR estimation. The addition of QMD to mean dominant height (HD) greatly improved height–d.b.h. relationship with a reduction of 8 per cent in RMSE, compared with the use of basal area per hectare. Similarly, multiplying a fundamental local model by using QMD raised to a parametric power reduced RMSE by 16 per cent, improved Fit index by 12 per cent and decreased the AIC value by 7 per cent. D.b.h., HD and RSI best explained the crown ratio relationship with an improved Fit index by 6.7 per cent compared with alternative non-linear models without RSI. The logistic model for CR also provided prediction accuracy similar to that of a commonly used non-linear model. A non-linear model with an application of remedial measures to enhance adherence to modelling assumptions can provide better parameter estimates than mixed-effects modelling approach.

Dendrolimus pini L. is a common and widespread moth in Europe, where severe outbreaks can defoliate Pinus sylvestris L. stands. Outbreaks are thought to be climate driven and may become more frequent and widespread with climate warming. The recent discovery of breeding populations of the moth in P. sylvestris plantations in Scotland has highlighted the importance of predicting outbreaks both within the core areas and at the margins of its current range. In this investigation, we used published data of damaging outbreaks plus historical climate data from Germany to build a relationship between climate conditions and outbreaks, and to develop a prediction model. Our analytical approach used principal component analysis and decision-tree data mining. German historical outbreaks showed relationships with climate variables, and provided evidence for a new damaging outbreak prediction model. The model uses the Seljaninov hydrothermal coefficient and decision-tree models on climate observations to predict where and when outbreaks may occur. The model was applied to European observed climate data and two climate projections using a GIS. In Europe, the model predicted future outbreaks in the Baltic States, Scandinavia, Russia and Scotland. In Scotland, more detailed analysis with probabilistic climate change projections showed an increasing risk of outbreaks through the twenty-first century.

There is little information about the impacts of past Sitka spruce (Picea sitchensis [Bong.] Carr.) tree breeding on wood properties because the emphasis has traditionally been on improving stem form and growth rates. This study used both SilviScan and mechanical testing to investigate the radial variations in wood stiffness, bending strength, density and microfibril angle in defect-free samples taken from the first United Kingdom progeny trial to reach merchantable size. We tested for differences in these radial patterns of variation in half-sibling progeny of three plus trees originally selected for superior growth rate and stem form against a non-selected control. Large differences in all of the properties were observed with radial position, with properties generally being less desirable in the corewood. Significant undesirable differences between the improved families and the control were found for stiffness, strength and microfibril angle. There was no significant relationship between wood density and stiffness in samples taken from the inner part of the tree, where stiffness was more closely associated with microfibril angle. Overall, previous selections for growth rate and/or stem form have compromised timber properties. It is recommended that current breeding programmes focus on corewood stiffness to prevent further degradation in the wood properties of the future timber supply.

To predict the value of trade between countries, a differential gravity model of bilateral trade flows was formulated and estimated with panel data from 2005 to 2014 for each of the commodity groups HS44 (wood and articles of wood), HS47 (pulp of wood, fibrous cellulosic material) and HS48 (paper and paperboard). The parameters were estimated with a large database by ordinary least squares, fixed-effects and random-effects methods. For the three commodity groups, the results were stable across methods. For HS44, exports were inelastic (0.33 ± 0.19) with respect to the gross domestic product (GDP) of exporters and elastic (1.95 ± 0.15) with the GDP of importers. For HS47, exports were elastic with respect to the exporters GDP (1.67 ± 0.55) and importers GDP (1.10 ± 0.36). Exports of HS48 were inelastic with the exporters GDP (0.81 ± 0.21) and elastic with respect to the importers (1.00 ± 0.14). For all three products, there were marked decreases in exports in 2009 and 2012 independent of GDP. The estimated elasticities were used to predict the growth rate of trade flows from 2015 to 2020 based on exogenous GDP projections of the International Monetary Fund. Another application investigated the effects of the Trans-Pacific Partnership agreement on the trade of forest products between the 12 member countries.

Sustainable methods are required to protect newly planted tree seedlings from insect herbivore attack. To this end, here Norway spruce (Picea abies (L.) Karst.) seeds were treated with 2.5 mM nicotinamide (NIC), 2.5 mM nicotinic acid (NIA), 3 mM jasmonic acid (JA) or 0.2 mM 5-azacytidine (5-Aza), and 6-month-old seedlings grown from these seeds were planted at a reforestation area in central Sweden. Attack by pine weevils (Hylobius abietis) was reduced by 50 per cent by NIC treatment, 62.5 per cent by JA treatment and 25 per cent by 5-Aza treatment, when compared with seedlings grown from untreated seeds. Watering 18-month-old spruce seedlings with 2 mM NIC or 2 mM NIA did reduce attack during the first season in the field by 40 and 53 per cent, respectively, compared with untreated plants. Girdling was also reduced by the different treatments. Analysis of conifer seedlings treated with 5-Aza points at a possible involvement of epigenetic mechanisms in this defensive capacity. This is supported by a reduced level of DNA methylation in the needles of young spruce seedlings grown in a greenhouse from NIC-treated seeds. Seed treatment for seedling defense potentiation is simple, inexpensive and also a new approach for forestry with many potential applications.

This study analyzed differences between actual and modelled fire predictions for two recent fires that affected the Golestan National Park in northeastern Iran. FARSITE and FlamMap minimum travel time (MTT) fire modelling systems were used to compare spatial differences in burned area between observed and modelled fires. Then, the spatial variability in fire spread and behaviour related to differences in fuel types and topography was analyzed. Comparison between the observed and simulated fire perimeters showed a relatively good agreement. For both case studies, the simulations performed with the MTT algorithm presented slightly higher accuracy than the FARSITE ones. Although we found spatial differences in fire intensity and rate of spread modelling outputs, the average values in burned areas provided by FARSITE and FlamMap MTT simulations were very similar. The comparison of fire spread models provided a better understanding of their potential limits and differences in fire growth and behaviour predictions over heterogeneous-fuel landscapes, complex topography and changing weather conditions.

National forest inventories (NFIs) have to be properly designed in order to yield statistically representative data and make best use of limited resources. A key element to accomplish this is the knowledge of the local variability in the sampled forest stand features. In this study, we estimated the variability of tree taxonomic richness and carbon (C) stock in logged-over and unlogged lowland tropical forests of Papua New Guinea, to define the optimal plot and sample size needed to estimate these characteristics in the context of the forthcoming implementation of the new NFI. We used data from 133 one-hectare permanent sample plots to calculate the coefficient of variation (CV) of C stock and taxonomic richness at different simulated plot sizes. CV was seen to rapidly decrease with increasing plot size up to 0.2–0.3 ha for both features following an inverse-exponential trend. Optimum plot size ranged between 0.08 and 0.32 ha, with 75–164 plots needed to achieve an estimation within 5 per cent of the true mean (95 per cent confidence), depending on the stand feature and the previous silvicultural treatment. We concluded that the establishment of a network of 319 permanent sample plots between 0.2 and 0.3 ha in size would represent an efficient sampling scheme in lowland forests for the new NFI.