With the continuing deposition of atmospheric nitrogen (N), N has become a major factor affecting ecosystem carbon (C) balance and N cycles. However, it is still unclear how increasing N deposition alters above- and below-ground biomass allocation, especially among different order roots. Pinus tabuliformis Carrière is an important native species in the Loess Plateau of China, as well as the preferred species for artificial afforestation in this area. Methods: One-year-old P. tabuliformis seedlings were treated with six different N concentrations (0, 0.02, 0.04, 0.08, 0.16, and 0.32 g N kg−1 soil year−1) for 3 years. Individual P. tabuliformis seedlings were separated into leaves, shoots, and roots in May 2011. Variations in leaf morphology, root characteristics, and their biomasses were investigated. Results: (1) The highest N fertilizer level (0.32 g N kg−1 soil year−1) significantly decreased leaf area, root length, and specific root area. (2) Lower levels of N significantly reduced root length, root diameter, and specific root area in the first- and second-order roots. (3) Leaf biomass increased significantly in the higher N treatments (0.02–0.08 g N kg−1 soil year−1). However, total seedling biomass under the highest treatment decreased significantly due to excessive N. Biomass of the roots and leaves in the 0.04 g N kg−1 soil year−1 treatment increased compared with that in the control. Conclusions: (1) The lower-order roots (and leaves) were more sensitive than the higher-order roots (and stems) to N application. (2) The specific root area to specific leaf area ratio might be more suitable than area or biomass indices in explaining the utilisation of N by plants. (3) The functional balance hypothesis did not adequately explain the distribution of photosynthetic products among P. tabuliformis organs, but the source-sink relationship hypothesis did. This indicates that roots were the main sink and received a greater distribution of photosynthetic products.

Establishment of exotic forest on erosion-prone pastoral hill country in the East Coast region of New Zealand escalated following a major cyclonic storm in 1988. Pinus radiata D.Don is the predominant species used for erosion control. It has been suggested that planting densities could be reduced if faster growing P. radiata seedlings and cuttings from genetically improved seed lots were used. Methods: A field-based trial was established to measure and compare annual growth rates between P. radiata seed lots (GF 16 and GF 19 seedlings and cuttings grown from GF 23 seed) used during the period of early forest establishment (1960s onwards) in this region and genetically improved seed lots (GF 27 seedlings and GF 28 cuttings) developed at a later date. Over a 4-year period, the above-ground parameters (diameter at breast height, root collar diameter, tree height and canopy diameter) were measured before whole trees (canopy and root systems) were destructively sampled. Results: Root collar diameter (over bark) was most highly correlated with tree height, with r2 ranging between 0.95 and 0.98 for all the seed lots, and all regressions were highly significant (P < 0.001). In any year of the trial, there were no differences among seed lots with respect to root collar diameter, total above-ground biomass or total below-ground biomass. By year 4, mean below-ground biomass comprised 17% of total biomass. There was no consistently significant difference among seed lots in the distribution of total below-ground biomass or root length with distance from the root bole, relative to depth, or in either their maximum lateral root spread or maximum root depth until year 4 when GF16S and GF27S had a greater (P = 0.05) maximum root spread than GF28C while the latter had developed a significantly greater (P = 0.05) proportion of its root biomass and root length within the top 0.5 m of the soil profile. The root cross-sectional area of vertical roots increased significantly with age but decreased with depth. Root orientation formed a ‘bilateral fan-shaped’ architecture. Conclusions: The absence of consistently significant differences among seed lots suggests that during the early 4 year post-establishment period, no one seed lot would provide earlier soil reinforcement or result in a superior level of slope stability than would any of the other seed lots trialled. Thus, irrespective of seed lot preferences, any reduction in the current recommended planting density for erosion-prone hill country would further increase the period of vulnerability and risk of young plantings to damage by storm-initiated landslides.

Renewable energy sources such as biomass are an important aspect of the energy policy of the European Union. As the use of ‘full-value wood’ for energy purposes has been restricted, short-rotation forestry may be an alternative source of woody biomass. In Poland, the most promising genus is poplar (Populus spp.). Methods: Ten poplar cultivars from the Aigeiros or Tacamahaca sections of the genus Populus were compared in 5- and 6-year rotations for biomass components and yields. Additional aims were to preliminarily (a) identify a suitable rotation length and (b) evaluate the sprouting capacity of various cultivars in the climate of northern Poland. The following variables were measured: diameter at breast height (DBH), height, survival rate, single-tree dry mass, crop biomass production, and sprouting ability. Results: The cultivars ‘NE-42’ and ‘Fritzi Pauley’ showed the best growth characteristics (DBH and height) and highest biomass production (7.6 and 7.7 t ha−1 year−1, and 5.2 and 6.9 t ha−1 year−1, respectively, for cultivars in the 5- and 6-year cycles). These cultivars were also distinguished by a large number of coppice shoots and a high shoot length. Eight cultivars did well enough to produce worthwhile data, and five of these gave higher biomass production (t DM ha−1 year−1) during the 6-year, as opposed to the 5-year cycle. Of the eight cultivars analysed, ‘AF-8’ had the poorest growth parameters and produced two thirds less dry biomass than either the ‘NE-42’ or ‘Fritzi Pauley’ cultivars. Data for two Italian cultivars (‘AF-6’ and ‘MON’) were not analysed because of their cold tenderness and their high mortality. Conclusions: Rotation length is important for biomass production in energy plantations. Most of the tested poplar cultivars gave higher biomass productivity over an initial 6-year cycle than over a 5-year one. Our preliminary results suggest that the ‘NE-42’ and ‘Fritzi Pauley’ cultivars performed best among those tested. Both of these have been tested previously in Poland in medium and long rotations. The data indicate the importance of testing cultivars under local climatic conditions before planting on a commercial scale.

Cyclaneusma needle cast (CNC) is a pine disease caused by the ascomycetous fungus Cyclaneusma minus (Butin) DiCosmo, Peredo and Minter. The pathogen occurs worldwide but is of particular significance in New Zealand where it infects Pinus radiata D. Don plantations. There are two morphological types of C. minus, termed C. minus ‘simile’ and C. minus ‘verum’, recently shown by multigene phylogenetic analysis to belong to distinct clades and therefore proposed to be two separate species. It is currently unknown whether one or both of these molecular operational taxonomic units (MOTUs) are responsible for CNC. Methods: In this study, DNA analysis of the rDNA internal transcribed spacer (ITS) region was carried out on 120 isolates of C. minus collected in New Zealand since 1969 to distinguish C. minus simile from C. minus verum. Specific primers for C. minus simile and C. minus verum were developed for molecular differentiation from pure cultures and direct amplification from infected needles. Using these specific primers, the distribution of C. minus simile and verum was determined from isolates collected throughout New Zealand. Results: The C. minus simile and C. minus verum primers developed were specific to these morphotypes only and were successfully used to identify simile and verum MOTUs from culture. Morphological typing of cultures was consistent with specific primer results in only 56% of isolates tested, demonstrating the high level of skill and experience required for accurate morphotyping from culture alone. C. minus simile was more common throughout New Zealand including regions where CNC is known to be more prevalent. From a collection of 120 isolates, 89% of North Island isolates and 59% of the South Island isolates were C. minus simile. The C. minus simile and verum specific primers were used to detect Cyclaneusma DNA in symptomatic P. radiata needles. C. minus simile was detected in 39% of the needle samples and C. minus verum was only detected in 11%. However, Cyclaneusma DNA was not detected by PCR in 50% of the sampled needles. Conclusions: The molecular methods developed for differentiation of C. minus simile and C. minus verum can be used to rapidly identify these morphotypes from cultures or from infected needles, which reduces the time otherwise required for morphological identification. Analysis using these tools for characterisation of C. minus sensu lato, isolated from P. radiata plantations in New Zealand since 1969, revealed that C. minus simile was more common than C. minus verum.

Increasing demand for renewable energy resources and the need to mitigate climate change have raised interest in short-rotation forestry with fast-growing deciduous trees like hybrid aspen (Populus tremula L. × P. tremuloides Michx.) in northern Europe. Given that climate warming has already considerably extended the growing season in this region, northward transfer of genotypes could improve forest plantation productivity and enable more efficient mitigation of climate change. We studied the spring and autumn phenology of hybrid aspen genotypes of different geographic origin (European P. tremula parent from 51° to 60° N and North American P. tremuloides parent from 45° to 54° N) 3 and 6 years after planting in a progeny trial established in Estonia at 58° N. Findings: The effect of geographic origin on spring and autumn phenology of hybrid aspen was evident at the age of 3 and 6 years. Geographic origin did not affect spring phenology. However, hybrids with P. tremula parents of northern origin, with bud-burst occurring some days later, were able to unfold and develop full-sized leaves faster than genotypes with early bud-burst. The main differences between different geographic origins appeared in the autumn of year 6, when genotypes of northern origin (60° N) started autumn defoliation significantly earlier than those of southern origin (51° to 57° N). The genotypes of southern origin (55° 53′ to 57° 31′ N) had a period from bud-burst to defoliation 27 days longer than that of genotypes of northern origin (60° 22′ N). The interval between spring and autumn phenological processes showed significant positive correlation with current annual height growth for both study years. Conclusions: Hybrid aspen genotypes from 55° to 57° N responded well to northward transfer, having a longer leafy period and greater height increment than southward transferred genotypes. Northward-transferred genotypes were apparently better adapted to climate-change-induced extension of the growing season at higher latitudes.

Mathematical modelling is often used to investigate phenomena difficult or impossible to measure experimentally. Findings: This paper presents the constants needed to mathematically model green Pinus radiata D.Don core- and outerwood. The constants include all three elastic and shear moduli along with the six Poisson ratios needed for describing orthotropic materials in the elastic domain. Further proportional limit surfaces are presented. Conclusions: The constants provided allow for an increase in realism of mathematical models examining the mechanical performance of standing trees.

Like most pines, radiata pine (Pinus radiata D.Don) is conventionally considered resistant to defoliation by European gypsy moth, i.e. it is only consumed by late larval stages, or when susceptible species are not available or are scarce. The ability of this moth to complete development on this host in field conditions has never been reported. Findings: A gypsy moth outbreak in a pure radiata pine plantation was observed in north-western Spain, where this insect is endemic. During the 2 years of outbreak culmination (2012 and 2013), approximately 46 ha of radiata pine were severely defoliated (>75 % of leaf area removed) and no defoliation was evident in nearby stands of susceptible species. Large numbers of egg masses were present on stems of pine trees. Larvae were observed feeding exclusively on radiata pine needles beginning with the first instar and continuing to pupation. Nearly 100 % tree mortality occurred in stands severely defoliated. Conclusions: The occurrence of a European gypsy moth outbreak in a pure radiata pine plantation contradicts previous observations that larvae of this species cannot complete development in stands comprised entirely of pines. These results suggest that European strains of the gypsy moth hold great potential for damage to commercial radiata pine plantations where this species is utilised in plantation forestry, such as in New Zealand or Australia.

The use of herbicides for weed control in New Zealand planted forestry is important for primary production. The objective of this study was to assess the environmental fate of terbuthylazine and hexazinone in a Recent Soil following an aerial post-plant herbicide application in a New Zealand planted forest. Methods: Soil and forest litter were collected from four plots within a recently harvested and replanted Pinus radiata experimental sub-catchment. Samples were taken before and up to 6 months after the aerial application of terbuthylazine and hexazinone. Findings : There was no drainage below 1-m depth in the first month after spray application. On the following month, there were six drainage events ranging from 12 to 36 mm. Both terbuthylazine and hexazinone were located predominantly in the 0–10 cm soil depth, followed by the litter layer with only small amounts detected below 10 cm soil depth. Following a month of drainage events, hexazinone showed an increase at a soil depth of 10–50 cm. Both terbuthylazine and hexazinone rapidly dissipated with time after spray application, and predicted half-lives for both active ingredients were less than 1 day. Conclusions: The first 2 weeks after spray application were found to pose the greatest potential risk of movement off-site, after which the risks were low. Organic matter management practices that influence the amount and distribution of forest floor, litter and harvest residue have an important role in determining the environmental fate of both terbuthylazine and hexazinone.

The use of herbicides to control competing vegetation in planted forests is an important component of forest management. The increasing public aversion to herbicide use includes the possible contamination of receiving aquatic environments. The risk of surface run-off, leaching and erosion processes transporting herbicide residues to waterways, is potentially higher in steepland forests containing soils with high leaching potential. The purpose of this study was to measure the concentrations of terbuthylazine and hexazinone, two herbicides commonly used in post-plant weed control in New Zealand, in waterways, when aerially applied in a steepland forest catchment with Recent Soils. Methods: Terbuthylazine and hexazinone were applied, at 6 and 1.5 kg ha−1, respectively, to 30 ha distributed over a 193-ha catchment. Herbicide concentrations were measured in stream water and sediment in a 12-ha headwater sub-catchment (W1) (57 % sprayed) and in stream water at two sites further down the catchment. These sites were monitored prior to, and for 5 months after, herbicide application. Results: The highest concentrations in stream water were recorded on the day of herbicide application at W1 (terbuthylazine, 9.6 μg L−1; hexazinone, 5.3 μg L−1). Terbuthylazine concentrations were above drinking water standards for several hours, well below the decadal time frame required to exceed these standards. Thereafter, concentrations rapidly declined, with the highest concentrations recorded 1 month after herbicide application, 2 days after a 50-mm (24 h) rainfall event. Concentrations declined downstream and were <5 μg L−1 where the stream exited the forested catchment. Terbuthylazine only was detected in sediment for up to 60 days after herbicide application. Concentrations and persistence of both herbicides in stream water were well below toxic levels for aquatic organisms. Conclusions: The potential risks to aquatic environments from herbicide application in steepland conditions were partially mitigated by the 30-m ‘no-spray’ zone along the stream margins, along with logging slash in the stream channel and the spatial distribution of the treated areas within the catchment. Under these operational conditions, and when applied according to manufacturer’s instructions, the downstream risks to human health and aquatic environments appeared to be low.

A ‘sampling frame’ identifies the sampling units in a population and their locations. It may consist of a listing of sampling units, or it may be based on a map of the population area within which sampling units can be observed. For inventory of large forests or other populations, it is common for no list of individual plants to exist, but it is common to have available a map of the area. When such a map is the only available sampling frame, methods are well established for drawing a simple random sample of fixed area plots. Less well-known methods are available if the sample is to consist of individual population members rather than groups of them in plots. Through simulation studies, the efficacies of two methods devised by Dr. K. Iles are considered for drawing a simple random sample of individuals given a map of the population area. Findings: It is shown that simple random samples of individuals can be drawn satisfactorily using such a map. Further, the estimates obtained from the population mean of individuals, and its precision, are the same as those obtained when a sampling frame consisting of a list of individuals is available. Estimates of the population total can be obtained also, but their precision will be lower than those obtained when a list is available. Conclusions: The absence of a list of individuals in a population does not preclude simple random sampling of individuals as long as a map of the population area is available. However, a preliminary survey of the population must then be made before sampling starts, and it may be necessary to visit many more sampling units to obtain the required sample than is the case when a list is available. The more complex the spatial arrangement of individuals within the population, the greater will be the number of sampling units that must be visited.

Polynomial taper models are the tree profile equation types that are most commonly used to describe stem profiles of New Zealand radiata pine (Pinus radiata D.Don). Among these equations are model forms that include an upper stem diameter measurement as a predictor. Such taper functions may be more costly to use given the need to measure the additional stem diameter. Therefore, it is important to have an insightful understanding of the contribution of the additional diameter measurement to taper model prediction bias and precision to better inform decisions on whether to develop advanced technology for, or invest in, tree upper stem diameter measurements(s) for taper equation use. Methods: Prediction precision and bias for diameter and volume were evaluated for a regular polynomial taper model with dbh and total height as tree-level predictors (DH model) and eight taper models that included an upper stem diameter as an additional tree-level predictor (DH+ models). Two sets of radiata pine stem sectional data from 66 stands across New Zealand were used in the investigation. Seventy percent of the trees in the larger one of the two sets were used for model fitting. The rest of the trees in the larger data set, and those in the remaining data set, were used for model validation. Results: A DH+ taper equation that included an upper stem diameter measured at half the distance between breast height and the tree tip exhibited the lowest prediction error for stem diameters. Most of the reductions in diameter prediction error, from use of this equation, occurred in the upper half of the tree bole. Tree-level volume predictions from both DH and DH+ taper models were unbiased across the range of tree sizes investigated, but DH+ models exhibited greater precision in volume prediction. Conclusions: Including an outside bark upper stem diameter, measured at half the distance between breast height and the tree tip, in a polynomial taper equation for New Zealand radiata pine may result in a considerable improvement in tree volume prediction precision especially for total aboveground volume. Use of a diameter measured at 6 m may not result in prediction precision that is different from that of a DH taper equation.

Broom (Cytisus scoparius (L.) Link) is an invasive weed in many commercial radiata pine (Pinus radiata D.Don) plantations throughout New Zealand. A variety of herbicides are available to selectively control young established broom plants during the first year after planting pines, but there is little published information describing which are safest for pines and most effective as the broom grows older. Methods: A pot experiment was conducted to assess the efficacy of six selective herbicide treatments applied at three rates (recommended (medium) rate, half (low) rate and double (high) rate) for controlling broom of various ages (3, 6, 9 and 12 months old). Five treatments involving registered herbicides were compared with fluroxypyr, which is not registered for use in radiata pine or on broom. As broom is a major competitor in plantation forestry, the adverse effects of these herbicides on 12-month-old radiata pine were also assessed. Results: The high rate of each treatment killed all the 3-, 6-, and 9-month-old broom plants, but only the high rate of hexazinone or the clopyralid/triclopyr mixture killed the 12-month-old broom plants. In addition, the medium rate of clopyralid/triclopyr, terbuthylazine or clopyralid/triclopyr/picloram/aminopyralid killed all 3-, 6-, and 9-month-old broom plants. The remaining treatments were not completely effective (i.e. median injury rating was less than 10). All of the registered herbicides caused minimal damage to radiata pine, but the damage caused by fluroxypyr to radiata pine was considered too great to recommend operational use of this chemical on its own. Conclusions: Mixtures based on clopyralid with triclopyr gave the best selective control of potted broom plants up to 12 months old. Such mixtures will also preserve grass ground covers. Although fluroxypyr is unsuitable for use by itself, it could be assessed in further work for use with clopyralid.

The diseased wood, agarwood, from the tropical tree taxa Aquilaria, is famed for its unique fragrance and medicinal values, mainly due to its richness in secondary metabolites such as the sesquiterpenes. The presence of sesquiterpenes in high numbers and amounts correlates with agarwood of high quality. Methods: To understand the synthesis of this important compound, we cloned two candidate genes in the terpenoid synthesis pathway from Aquilaria malaccensis Lam., a major agarwood tree speciesThe genes encoding sesquiterpene synthase (AmSesTPS1) and δ-guaiene synthase (AmGuaiS1) were successfully cloned from callus RNA, using specific primers derived from transcriptomic data, in a reverse transcription PCR reaction. Results: The full-length complementary DNA (cDNA) sequence of AmSesTPS1 was 1632 bp encoding for 544 amino acids, and AmGuaiS1 was 1644 bp encoding for 547 amino acids. Sequence alignment analysis showed that AmSesTPS1 shared between 99 to 100 % identity with sesquiterpene synthase from Aquilaria sinensis (Lour.) Sprengwhile AmGuaiS1 shared between 95 to 99 % identity with δ-guaiene synthases from Aquilaria crassna Pierre ex Lecomte and Asinensis. The genes were functionally characterised in a time course wounding experiment using 3-year-old living trees. Two types of wood samples were collected: (1) from wounded area (S1) and (2) from 5 cm below the wounded area (S2)AmSesTPS1 was highly expressed after 6 h post wounding for both S1 and S2, at a level three- to six-fold higher than that of the unwounded control (0 h), while AmGuaiS1 was induced after just 2 h of wounding (18- and 5.5-fold at S1 and S2, respectively), after which the expression of both genes was lowered. The average normalised expression of both genes at S1 and S2 indicates the genes were also unregulated in the distal area from the wounding site. Conclusions: It can be deduced that wounding triggers these two genes in the sesquiterpene synthesis pathway, which ultimately leads to agarwood formation.

Acoustic tools have simplified estimation of wood modulus of elasticity (MOE). Strong relationships between acoustic velocity and MOE of logs have encouraged use of acoustics at earlier points in the value chain, culminating in the development of acoustic harvesting systems. With accurate estimates of MOE of individual trees, improvements in efficiency along the value chain and increased value recovery will result. Our aim was to quantify the accuracy of MOE estimates at three distinct points: pre-harvest (standing trees), during harvest (merchantable boles), and post-harvest (5-m logs). We hypothesised that: (1) MOE estimated from acoustic velocity and wood density would provide greatest accuracy; and (2) bole estimates with a resonance tool would be more accurate than tree estimates with a time-of-flight tool. Methods: A sample of 168 Douglas-fir (Pseudotsuga menziesii [Mirb. Franco]) trees, representing the variability in acoustic velocity of 700 standing 36–51-year-old trees, was harvested from three sites. Prior to harvest, time-of-flight and breast-height diameter were recorded. After felling, resonance velocities of boles and subsequent 5-m logs were recorded. Discs, cut from log ends, were immersed, and green wood density determined. Half the logs were processed into boards, the other half into veneer sheets, and all products (in excess of 6000) non-destructively tested for MOE. MOE of parent trees, boles, and logs was then calculated from the mean MOE of derived products. Predictive mixed-effects models of tree, bole, and log MOE were developed using data from 139 trees. Fixed effects comprised combinations of velocity squared, wood density, acoustic MOE (derived from the wave equation), diameter, height, taper, and age. Random effects comprised site, plot, and, at the log level, tree. The models were validated using data from the remaining trees and compared using multiple performance metrics. Results: For estimating tree MOE, a model with velocity squared, wood density, and taper as predictors is recommended. For estimating MOE of boles and logs, models with velocity squared and wood density are recommended. The models have an accuracy, as determined by RMSE, of about ± 2 GPa. Conclusions: For accurate MOE estimation, velocity alone is insufficient. Knowledge of wood density is necessary for improved accuracy.

Russia’s boreal forests are a major source of timber as well as being a large terrestrial sink for carbon. Planted forests have played an important role in increasing the overall area of the Russian boreal forest. The total area of planted stands in republics and oblasts of the Middle Volga Region is about 3.2 million ha. Scots pine (Pinus sylvestris L.) is the most widespread species in planted forests of the Middle Volga Region. As a result of its mass planting since the 1950s, the proportion of pine forests increased from 21 to 29 %. In order to justify the continued use of artificial regeneration to re-establish forests after harvest, more information is required on the growth and yield of planted and natural Scots pine forests. Therefore, the main objective of this study was to quantify and compare the productivity of planted Scots pine forests with that of natural forests in the Middle Volga Region. Methods: Data were obtained from seven representative forests in the republics and oblasts of the Middle Volga Region spanning the period between 1961 and 2007. The relationship between total standing volume and stand age was modelled for both planted and natural stands of Scots pine using the nonlinear Mitscherlich equation. Results: Planted Scots pine forests generally have a higher relative stand density than natural forests, due to the presence of natural regeneration in planted stands. Mean annual volume increment of planted Scots pine forests was 5.6–9.2 m3/ha, which is approximately 15 % greater than the volume increment of natural Scots pine forests. Conclusions: Artificial stands are of high importance for maintenance of resource potential of Russian boreal forests. Mathematical and statistic calculations show benefits of planted Scots pine in comparison with natural pines in height, volume, density, productivity and growing stock increment. The achieved results suggest that wood can be obtained at an earlier age from planted forests thus preserving natural boreal forests.

An understanding of how plantation productivity varies spatially is important for forest planning, management and projection of future plantation yields and returns. The 300 Index is a volume productivity index developed for Pinus radiata D.Don that has been widely used within New Zealand to assess site productivity. Although the 300 Index is routinely characterised at the stand level, little research has investigated if remotely sensed data sources can be used in combination with environmental layers to precisely predict this metric at fine spatial resolution. Methods: This study uses an extensive dataset obtained from P. radiata plantations in the central North Island, New Zealand. Using this dataset, the objective of this research was to compare the precision of parametric and non-parametric models of the 300 Index that included explanatory variables extracted from aerially acquired light detection and ranging (LiDAR), satellite imagery (RapidEye) at 5-m resolution or environmental layers and combinations of these three data sources. Models were constructed both with and without stand age as an explanatory variable as managers may not always have access to stand age. A total of 28 models (14 data sources × two model methods) were constructed using data from 433 plots. Precision and bias of these models was determined using an independent dataset of 60 plots. Results: Of the non-parametric methods tested (k-most similar neighbour (k-MSN), k-nearest neighbour (k-NN)), k-NN using an optimised value of k-most precisely predicted the 300 Index for 11 of the 14 constructed models. The use of k-NN was found to be more precise than parametric models when age was not available but of overall similar precision to parametric models when stand age was available as a predictor. For models including stand age, the inclusion of LiDAR resulted in the most precise model (mean R2 = 0.789; root mean square error (RMSE) = 2.48 m3 ha−1 year−1) while for models without stand age, metrics extracted from both satellite imagery and environmental layers produced the most precise model of the 300 Index (R2 = 0.65; RMSE = 3.21 m3 ha−1 year−1). Conclusions: Results clearly show that models constructed from LiDAR provide the most precise means of estimating the 300 Index. However, in many situations, LiDAR is too expensive to acquire or stand age, which is used as a reference for linking LiDAR to 300 Index, is not available as an independent variable. Under these circumstances, results show that precise models can be constructed from variables derived from the combination of satellite imagery and environmental surfaces.

Density is a key wood quality trait, which is moderately to highly heritable, and has been the focus of selective breeding efforts in radiata pine (Pinus radiata D.Don) in New Zealand. Forest managers require information on realised gain in wood density in order to help them make decisions about which tree stocks to plant, how to manage stands and when to harvest in order to achieve certain wood quality outcomes. The aim of this study was to quantify realised genetic gain in radiata pine wood density and to incorporate it into existing modelling systems for predicting growth and wood quality. Methods: A national model of radiata pine wood density, which predicts wood density at breast height as a function of ring number from the pith and a “local parameter”, was modified to account for the effects of genetic improvement. The value of this local parameter was estimated for 679 radiata pine families with differing levels of genetic improvement (as quantified by their GF Plus rating for wood density) that were growing in 18 trials established by the Radiata Pine Breeding Company. The value of Wood Density Index (defined as the breast height outerwood density at age 20 years) was calculated from the estimate of the local parameter. Simulations were performed to show the impact of genetic improvement on whole-log average density and the variation in density within a log. Results: There was a strong positive relationship between GF Plus rating for wood density and Wood Density Index (R2 = 0.73), with a one-unit increase in GF Plus corresponding to a 2.16 kg m−3 increase in wood density. An increase in GF Plus density rating from 18 to 27 would result in an increase in breast height outerwood density at age 20 years of 18.5 kg m−3. Over the same range of genetic improvement, average whole-log density is predicted to increase by 14–16 kg m−3. Validation of the model using independent data from older trees showed that it was able to correctly predict the effect of genetic improvement. It also indicated that the assumption that the expression of genetic gain is constant across sites with different wood density potentials is valid, although data from additional trials located across a wider range of sites is required to confirm this. Conclusions: The effect of genetic improvement on wood density has been quantified and included in growth and yield modelling systems. This enables forest managers to estimate wood density in radiata pine plantations for any site and management regime established using tree stocks with a specific wood density rating.

Progesterone 5β-reductases (P5ßRs) catalyse one step in the stereospecific biosynthesis of cardenolides (potent repellents of herbivores and pharmaceutical stimulants of disordered heart muscle cells). They were originally discovered in the genus Digitalis and have since been frequently isolated from other angiosperms. Recombinant P5ßRs engineered in Escherichia coli host cells convert a broad spectrum of compounds in vitro, sometimes with higher efficiency than with progesterone. This observation suggests additional functions for cardenolide metabolism and promises future use in sustainable chemistry and biotechnology. Methods: A tissue complementary DNA (cDNA) library was screened for orthologous P5ßRs. Candidates were subcloned into expression vectors and overexpressed in E. coli cells. The recombinant P5ßR protein was investigated for catalytic activity with several related substrates. Using spectrophotometric assays, the biochemical parameters of the enzyme were calculated. A 3D model was created and was compared to the previously published P5ßR structure of Digitalis lanata and other plant P5ßR models. Results: Performing protein similarity searches in public databases and comparison of 3D protein structure models revealed four cDNA clones in a tissue library of Picea sitchensis (Bong.) Carrière putatively encoding P5ßRs. Succeeding with the expression of one clone in E. coli, the highly purified protein was unambiguously able to enantioselectively convert progesterone into 5ß-pregnane-3,20-dione. However, the catalytic activity to reduce the small molecule 2-cyclohexen-1-one was nearly 100 times faster. Methyl vinyl ketone was reduced similar to results from previously studied angiosperm resources. Conclusions: (i) The low catalytic efficiency for progesterone conversion agrees with the fact that conifers have not been reported to accumulate cardenolides. This finding suggests that alternate metabolic processes occur whereby the newly detected enzymes could transform smaller molecules rather than large ones such as progesterone. (ii) An ancient P5ßR gene appears to have existed in the last common ancestor of seed plants approximately 300 million years ago. If the diversification of P5ßRs, including the currently detected homologous iridoid synthase activity, was related to stress encountered during the transition to growth on land, then investigation of P5ßRs from pteridophytes and bryophytes should improve our knowledge of this enzyme class and elucidate the direction of evolution.

Female parasitoids that display aggressive behaviour towards conspecifics in defence of host resources must make a trade-off between time spent on aggression and time spent on parasitism. Such a trade-off not only affects the fitness of individual females but also may affect the overall rate of parasitism in the host population. Enoggera nassaui is an egg parasitoid of the eucalypt pest, Paropsis charybdis, with females that defend batches of host eggs from conspecific females by chasing, pushing and sometimes biting their opponent. Methods: The behaviour of female E. nassaui was observed when alone (solo) and in pairs (owner-intruder) in response to a single batch of P. charybdis eggs. The first female in a pair to contact the host eggs was designated the owner and the second female the intruder. Both parasitism-related behaviour for solo and paired females and aggressive interactions between paired females were described from direct observation. Parasitism rates for solo and paired females were also measured. Results: Solo females had a consistent pattern of parasitism-related behaviour, spending 80 % of their time in contact with the host eggs. Paired females showed a similar pattern of parasitism-related behaviour when not interrupted by their competitor. Owners spent 6 % and intruders spent 17 % of their time on aggressive interactions. Intruders completed parasitism faster than solo females because intruders reduced the duration of specific parasitism-related behaviours. Yet from the host’s perspective, parasitism by solo females (69 %) was similar to that achieved by both owners and intruders together (66 %). Conclusions: By completing parasitism faster in the presence of a competitor, intruder females compensated to some extent for time spent on aggressive interactions. If E. nassaui has a similar response to intraspecific competitors under natural conditions, then aggression between conspecific females is unlikely to harm pest suppression by these parasitoids.

A large population of Paropsisterna beata (eucalyptus leaf beetle) was detected on Eucalyptus nitens (H. Deane & Maiden) Maiden (Myrtaceae) at Whitemans Valley, a suburb east of Upper Hutt, Wellington, in 2012. The suburb is a semi-rural residential area with a large number of eucalypt, planted for amenity, shelterbelt and firewood. Surveillance to delimit spread showed that the beetle population was confined to about 0.7 ha consisting of about 40 eucalypts. The Ministry for Primary Industries (MPI) initiated a response to eradicate the beetle population. Findings: Aerial applications of Dominex EC 100 (alpha-cypermethrin) and ground applications of Talstar (bifenthrin) respectively over a 15-month period targeted the adults and larvae in the foliage and the pre-pupae, larvae and emerging adults in the leaf litter. Removal of overwintering habitat by stripping loose bark from host trees further reduced the beetle population. Following these treatments, the beetle has not been detected through a series of surveys using light traps, bark inspection, sticky tapes, visual inspection from the ground, climbing and felling host trees for inspection for 2 years since the last detection of two adults on neighbouring trees. Conclusions: The P. beata population has been successfully eradicated using a combination of aerial and ground-based application of insecticides. The use of precision aerial applications (spot-spraying) has provided an additional tool for incursion response.

The control of erosion processes is an important issue worldwide. In New Zealand, previous studies have shown the benefits of reforestation or bioengineering measures to control erosion. The impetus for this work focuses on linking recent research to the needs of practitioners by formulating quantitative guidelines for planning and evaluation of ground bioengineering stabilisation measures. Methods: Two root distribution datasets of ‘Veronese’ poplar (Populus deltoides x nigra) were used to calibrate a root distribution model for application on single root systems and to interacting root systems at the hillslope scale. The root distribution model results were then used for slope stability calculations in order to quantitatively evaluate the mechanical stabilisation effects of spaced trees on pastoral hillslopes. Results: This study shows that root distribution data are important inputs for quantifying root reinforcement at the hillslope scale, and that root distribution strongly depends on local environmental conditions and on the tree planting density. The results also show that the combination of soil mechanical properties (soil angle of internal friction and cohesion) and topographic conditions (slope inclination) are the major parameters to define how much root reinforcement is needed to stabilise a specific slope, and thus the spacing of the trees to achieve this. Conclusions: For the worst scenarios, effective root reinforcement (>2 kPa) is reached for tree spacing ranging from 2500 stems per hectare (sph) for 0.1 m stem diameter at breast height (DBH) to 300 sph for 0.3 m stem DBH. In ideal growing conditions, tree spacing less than 100 sph is sufficient for stem DBH greater than 0.15 m. New quantitative information gained from this study can provide a basis for evaluating planting strategies using poplar trees for erosion control on pastoral hill country in New Zealand.

The productivity of fast-growing forest plantation stands varies across short distances depending on site and forest characteristics. This indicates that forest managers would benefit from a site-specific approach to forest management. One tool used to characterise such productivity variations is a yield map, and a cost-effective source of data for these maps is automatically collected by harvesters. In order to generate such maps, it is necessary to understand the effect of geospatial accuracy of tree location recorded by the harvester. Methods: This study investigated data sets from four stands, and very accurate tree location was available for two of these. The tree-location data for the remaining two sites were collected by a harvester and contained some inaccuracies associated with Global Navigation Satellite System (GNSS) recording under forest canopy and the physical dislocation of the GNSS. The GNSS unit is on the cabin of the machine, but the tree is felled using a boom and could be up to 12 m from the cabin. Results: A suitable spatial resolution for studying variations in stand productivity, mean tree volume, and stocking rate across stands were established that enabled useful forest-yield maps from harvester data to be developed. Conclusions: By assessing variability in volume per hectare, stocking rate, and mean tree volume across a range of cell sizes from 10 × 10 to 100 × 100 m, we conclude that a cell length between 30 and 40 m is suitable for use as a reference when calculating volume per hectare and mean stem volume, while a 60-m-long cell is more suitable for evaluating stocking density. The variability pattern is consistent for the various accuracy levels. When the known positions of trees are relatively inaccurate, using mean tree volume and stocking rate per cell might be a method for mapping productivity from harvester data.

Three named species of Armillaria are currently recognised as occurring in New Zealand: Armillaria novae-zelandiae (G. Stev.) Herink, A. limonea (G. Stev.) Boesew. and Armillaria hinnulea Kile & Watling. A fourth species (Armillaria sp. nov.) has been collected in New Zealand over a period of 30 years but has not yet been named. Methods: Maximum likelihood analysis, using DNA sequence data from the internal transcribed spacer region (ITS) of the ribosomal DNA repeat, DNA sequencing of the elongation factor 1-α gene, cultural pairing studies and morphological examination were undertaken to confirm the novelty of Armillaria sp. nov. as a distinct species. Results: Armillaria sp. nov. is distinguished by the morphology of the fresh basidiocarp, cultural interfertility tests with other Armillaria species and DNA sequence data. Conclusions: Armillaria sp. nov. is here formally named Armillaria aotearoa.

Poplar trees (Populus spp.) are used widely for soil conservation. A key advantage is their ability to establish from unrooted stem sections of varying dimensions, ranging from small cuttings to large poles. This study determined root length and biomass of young trees from three different-sized stem sections and quantified clonal variation. Methods: Two concurrent field trials were conducted: trial 1 compared root attributes of trees from cuttings, stakes, and poles of a single poplar clone, while trial 2 compared those of trees from cuttings of six poplar clones. Excavations of entire trees were conducted in autumn for three (trial 1) or two (trial 2) years after planting. Results: Total root mass averaged over 3 years was in the order poles (364 g) > stakes (70 g) > cuttings (17 g), and total root length was in the order poles (73 m) > stakes (21 m) > cuttings (7 m). Maximum lateral root extension was approximately 2.6 m from poles, 1.7 m from stakes, and 0.8 m from cuttings. Clonal variation in trees from cuttings was found for both mean total root mass (10.4–45.9 g) and total root length (3.5–11.8 m). In both trials, root mass and length increased, decreased, or were unchanged with increasing 0.5-m increments of the distance from stem and soil depth, depending on year, planting material, root diameter, and their interaction. Conclusions: Early root development from poles was greater than from cuttings, with development from stakes being intermediate. Different poplar clones exhibited large variation in root biomass development within 2 years of planting. The results provide an understanding of the differences in early root development of poplar planting materials and clones used for soil conservation and other purposes and guidance on appropriate tree spacings of different planting materials to achieve root interlock.