Alan Leckie

The objectives of this study were to determine the influence of site, fertilisation and age on fibre length and develop predictive models of fibre length from a comprehensive set of climatic, edaphic and stand variables. Data were collected from a nationwide set of 22 site quality plots where Pinus radiata D. Don was established at high stand densities (40000stemsha−1) and

Resin pockets are found in the xylem of conifers belonging to four main genera and can generally be classified into two types. Type 1 are radially narrow discontinuities in the wood while Type 2 are radially flattened, contain less callus tissue, and are open to the external environment at early stages in their development. Although resin pockets are a major cause of degrade for appearance grade timber little is known about the environmental conditions that control the incidence of these defects. In this study we collected data from 15 year old Pinus radiata D. Don stands at four sites covering a wide environmental gradient. Resin pocket frequency was determined by cutting the lower 5 m of each tree into 50 mm sections. Each of these sections was then imaged and resin pockets were identified and allocated to a type, height and year of occurrence. Using these data, the objectives of this study were to (i) determine whether there is a significant relationship between the incidence of ...

Objective The aim of this study was to assess the potential use of δ13C in a future breeding program for selection of radiata pine genotypes with high water use efficiency (WUE) and better growth performance under drought-prone conditions through quantifying the genetic variation in needle δ13C (a surrogate index of WUE), height and diameter growth of 20 individual trees of 120 open pollinated radiata pine families, and determining the genetic correlations among these traits. Key Results 1. At age 7.5 years, the large phenotypic variation was found for needle δ13C, which varied over a range of -5.09‰ (28.34‰ ~ 23.25‰, equivalent to WUEi of 60-113 μmol CO2 mol−1 H2O) among individual trees. 2. The five traits measured at age 7.5 years showed variable levels of genetic control. The narrow-sense heritability estimates were very low for stem malformation (0.09 ± 0.03), low for stem straightness (0.16 ± 0.05), tree height (0.12 ± 0.03) and DBH (0.20 ± 0.04), but moderate for needle δ13C ...

ABSTRACT A recent trial found that the presence of coarse soil in fine soil increased nutrient uptake by two plant species (Smaill et al., 2014). To determine if the additional nutrient uptake was derived directly from the coarse soil, the changes in coarse soil nutrient stocks were assessed. In most cases nutrient stocks increased, despite being associated with greater plant nutrient uptake. This suggests coarse soil can promote nutrient release from fine soil through some currently unknown mechanism.

ABSTRACT Two trials established at contrasting sites with different soil nutrient and water availability at Balmoral in Canterbury and Aniseed Valley in Nelson, New Zealand were examined to (1) quantify the genotypic variation in foliar nutrient concentrations, δ13C and δ15N of 45 Pinus radiata genotypes in relation to tree growth and (2) determine the genotype by environment interactions for these traits. Significant genotypic differences were found in foliar nutrient concentrations, δ13C and δ15N. There were significant differences among the genotypes in tree growth, with some genotypes performing consistently better and some poorer across sites. The interaction of site by genotype was also highly significant for all growth variables and significant for some foliar nutrients (Ca, Mg and Mn). Significant correlations were found between growth variables and foliar nutrient concentrations or δ15N of the 45 genotypes at both sites. Stepwise multiple regression analyses of tree growth variables against foliar nutrient concentrations showed P, Fe, Mg, K, S and N at Aniseed Valley and δ15N, N, Mn and S at Balmoral contributed significantly (P < 0.05) to the models, respectively. This study indicated that foliar nutrient concentration and δ13C could be used as the potential indicators for screening Pinus radiata genotypes with better growth under the nutrient and moisture limiting conditions in New Zealand.

Biosolids management has been largely overlooked as an issue for environmental co-management, collaborative learning and public participation. This paper summarises four research projects on facilitating community involvement in biosolids management in New Zealand. The authors situate these studies both in relation to the New Zealand institutional and policy context for the management of biosolids and in relation to the themes of public participation and social learning in the literature on community involvement in environmental management. From the studies it can be concluded that: the incorporation of the knowledge and views of Māori is important from both public-participation and social-learning perspectives; both public-participation and social-learning approaches must consider the role of issue-definition in relation to willingness to participate; democratic accountability remains a challenge for both approaches; and locating biosolids management within an integrated water-and-wastewater or sustainable waste-management strategy may facilitate wider community participation as well as better-coordinated decision-making.

The objectives of this study were to determine the influence of site, fertilisation and age on fibre length and develop predictive models of fibre length from a comprehensive set of climatic, edaphic and stand variables. Data were collected from a nationwide set of 22 site quality plots where Pinus radiata D. Don was established at high stand densities (40000stemsha−1) and

Two trials, which included 5 boron (B) fertiliser rates (0, 4, 8, 16 and 32kgBha−1) and two weed control (±WC) and eight radiata pine genotypes, were established at two contrasting sites located respectively in North and South Islands of New Zealand to (i) investigate the influence of B fertiliser application rates on soil available B, foliar nutrients, tree survival and

ABSTRACT Two field trials established at contrasting sites (Kaingaroa and Rolleston) with different silvicultural treatments [magnesium (Mg) fertilizer or plus or minus weed control (±WC)] but identical clones of Pinus radiata were measured at age 6 for tree height (Ht), diameter at breast height (DBH) and ground-line (GLD), and modulus of elasticity (MOE) of standing trees. This study was undertaken to (i) quantify the main and interactive effects of clone, site, Mg fertilizer or WC on stem slenderness and corewood MOE of juvenile radiata pine, and (ii) examine the relationships between clonal means of corewood MOE and stem slenderness from 15 selected clones. At the Kaingaroa site, clone had a significant (P < 0.001) influence on stem slenderness and corewood MOE, which exhibited a 1.5-fold variation (1.48–2.33 GPa). The Mg fertilizer effect on MOE was not significant. At the Rolleston site, both WC and clone had significant (P < 0.001) influence on corewood MOE. Compared to �WC, +WC reduced MOE by 7%. The MOE exhibited a 1.7-fold variation (1.67–2.83 GPa) among the 15 clones. Across both sites, MOE exhibited a 1.5-fold variation (1.65–2.55 GPa) among the 15 clones. Overall, clonal differences in MOE were substantial and larger than the differences due to site and WC. Significant interactions were also found between clone and Mg fertilizer, clone and WC, and clone and site. This study for the first time showed the clonal means of MOE was strongly and positively correlated to clonal means of stem slenderness. This study has the important implication for forest managers that clonal material can be closely matched to site conditions and management regimes to optimise product value.

A hybrid tree growth model sensitive to competition from a diverse range of weed species was developed and validated using data from a nationwide series of 24 plots covering an extensive environmental gradient. Tree growth in plots with weeds over the first 3 years following establishment was predicted by reducing potential growth from an empirically determined optimum rate for the site (weed free) using a competition modifier, which accounts for the degree of weed competition for both light and water availability. Diameter growth of trees in plots with weeds was initially predicted by including a light competition modifier into the model developed for weed-free plots. This model accounted for 87% of the variance in diameter of trees growing with weeds. Although inclusion of this modifier provided unbiased predictions of tree diameter growth on wet sites, model predictions overestimated diameter growth on dryland sites by on average 11%. Addition of a competition index for water bas...