Tree Nutrition Research Articles

Total vs. internal element concentrations in Scots pine needles along a sulphur and metal pollution gradient

Analysis of foliar elements is a commonly used method for studying tree nutrition and for monitoring the impacts of air pollutants on forest ecosystems. Interpretations based on the results of foliar element analysis may, however, be different in nutrition vs. monitoring studies. We studied the impacts of severe sulphur and metal (mainly Cu and Ni) pollution on the element concentrations (Al, Ca, Cu, Fe, K, Mg, Mn, Ni, P, Pb, S and Zn) in Scots pine ( Pinus sylvestris L.) foliage along an airborne sulphur and metal pollution gradient. Emphasis was put on determining the contribution of air-borne particles that have accumulated on needle surfaces to the total foliage concentrations. A comparison of two soil extraction methods was carried out in order to obtain a reliable estimate of plant-available element concentrations in the soil. Element concentrations in the soil showed only a weak relationship with internal foliar concentrations. There were no clear differences between the total and internal needle S concentrations along the gradient, whereas at the plot closest to the metal smelter complex the total Cu concentrations in the youngest needles were 1.3-fold and Ni concentrations over 1.6-fold higher than the internal needle concentrations. Chloroform-extracted surface wax was found to have Ni and Cu concentrations of as high as 3000 and 600 μg/g of wax, respectively. Our results suggest that bioindicator studies (e.g. monitoring studies) may require different foliar analysis techniques from those used in studies on the nutritional status of trees.

INFLUENCE OF FOLIAR NUTRITION WITH MACROELEMENTS ON APPLE TREE GENERATIVE ACTIVITY: PHYSIOLOGICAL ASPECTS

In orchards of southern horticultural zones of Russia (alluvial-meadow and chernozemic-alkaline soils) studies of foliar nutrition of apple trees with different macroelements (N, P, K) were carried out aimed at regulating their generative activity. It was observed that foliar nutrition with urea and nitroammophoska exerted a positive influence оn the photosynthetic activity of apple trees and increased the transfer of metabolites from leaves to absorption sinks (seeds and fruit tissues). Nitroammophoska influenced the generative activity of apple trees more effectively than urea. Treatment of trees with nitroammophoska at an early fruit stage (organogenesis stages X-XI) increased substantially seed viability and improved tree productivity in terms of both total yield and fruit size. Moreover, this mineral fertilizer applied at the stage of decreasing shoot growth (before organogenesis stages III and IV) provided varieties of different ripening periods with substantial improvement of flower bud formation. Thus, foliar application of nitroammophoska at defined organogenesis stages gives the possibility to specifically regulate the production process; it may increase annual fruit yield and quality of seeds.

Influence of edaphic factors and tree nutritive status on the productivity of Pinus radiata D. Don plantations in northwestern Spain

Relationships among soil parameters, tree nutrition and site index (SI) were examined in Pinus radiata plantations growing on soils developed from different parent materials (acid schist, granitic rocks and basic rocks) in a climatically homogeneous areas of NW Spain. Soil depth, in association with soil water balance and nutrient store, had the greatest influence on the productivity of these plantations. Although foliar N and K were sufficient in every stand studied, widespread deficiencies of P, Mg and, to a lesser extent, Ca were diagnosed. Foliar concentrations of Ca and Mg were positively correlated with soil nutrient concentrations. The main factors affecting site quality were identified with principal component analysis. The SI was positively correlated with foliar P concentrations, soil depth and pH, and negatively correlated with soil total N. Approximately 60% of the observed SI variation was accounted for by these soil properties. The results suggest the importance of site selection and fertilizer treatments in reforestation programmes.

The effects of slash management on nutrient cycling and tree growth in Eucalyptus plantations in the Congo

Since 1978, 42,000 ha of clonal Eucalyptus plantations have been established around Pointe-Noire. These plantations are growing on sandy and acidic soils with small reserves of available nutrients; therefore, risks of nutrient deficiencies exist in the medium or long-term. The effects of slash and litter management practices on soil properties, tree nutrition and growth were quantified to evaluate harvesting methods with respect to sustainable management of the replanted sites. The experimental design was a randomized complete block with four replications and six treatments: R, all aboveground organic residues removed; WTH, whole-trees harvested and removed; SBH, stemwood and bark removed; SH, stemwood-only removed; DS, double slash retained; B, stemwood-only removed and all organic residues burned. After 12 months removal of all slash material (R) had a marked negative effect on total biomass (5.9 t ha −1 vs a mean of 7.2 t ha −1 for the other treatments). During the first 18 months of the study no significant differences among treatments were detected ( P<0.05), but at 24 months, tree growth was significantly reduced where all organic residues were removed (R), compared to DS (12.9 m 3 ha −1 per year vs 22.2 m 3 ha −1 per year). The best growth was measured in plots with the highest organic residues (treatments DS and SH). Nutrient content in the aboveground biomass of the 1-year-old stand was strongly dependent on the type of slash and litter management. Differences in tree nutrient concentrations in various treatments demonstrated the ability of trees to store available nutrients in aboveground biomass. The rate of decomposition of organic residues during the first 8 months after harvesting ranged from 36% (WTH) to 56% (SH). Between 7 and 24 months, the annual production of inorganic nitrogen in the top soil (0–13 cm layer) was 71.6, 66.7, and 85.7 kg ha −1 per year for R, SH, and DS, respectively. The rate of soil nitrification was high, and therefore nitrogen leaching may have occurred in the early development stage when trees are not able to take up all the available nitrogen.

Atmospheric deposition in oligotrophic Quercus pyrenaica forests: implications for forest nutrition

The aim of this study was to analyze the contribution of atmospheric input of elements to tree nutrition in an oligotrophic forest ecosystem of Quercus pyrenaica, located in a low polluted area. The work was conducted over 3 years in four permanent plots, in the “ Sierra de Gata” mountains (CW Spain). To calculate total (wet and dry) atmospheric deposition, we measured element inputs via bulk precipitation (BP), throughfall (TF), stemflow (SF), and dry deposition (DD) (filter gauge method). Available soil and leaf nutrient contents were also analyzed. Aboveground tree nutrient demand was estimated from annual tree growth and nutrient concentrations in trunks, branches, and leaves. Atmospheric depositions were low, especially for N (5.9 kg N ha −1 per year) and S (7 kg S ha −1 per year), as expected in an unpolluted area. BP dominated atmospheric deposition, but DD represented an important input of nutrients, especially for N, S, P, K, Mg, and Ca (2.2, 2.2, 0.6, 3.6, 1.4, and 3.4 kg ha −1 per year, respectively). Low soil contents of N, P, and exchangeable cations were related to low canopy leaching rates, or even to canopy uptakes, showing a certain degree of self-regulation. In fact, the differences in canopy exchange (CE) found between the plots were strongly correlated to leaf contents ( r>0.9, for Mn, Mg, K and P). Comparison of annual aboveground accumulation of nutrients with total annual atmospheric deposition showed that the deposition amount was much higher than the annual demand of the trees for Na, S, and Zn. For P, K, Mn, and Mg annual atmospheric deposition matched the annual tree demand for aboveground growth. For N and Ca, atmospheric depositions reached between 58 and 31%, respectively, of the annual demands. This contribution by atmospheric depositions would explain why these forest ecosystems have persisted in poor soils subjected to permanent and long-lasting losses of nutrients through biomass removal (i.e. leaves, timber, and grazing).

The severity of Sirococcus shoot blight in mature Norway spruce stands with regard to tree nutrition, topography and stand age

In this study the impact of tree nutrition, topography and stand age upon incidence and severity of Sirococcus shoot blight was evaluated in a research area located in the Kobernaußerwald in Upper Austria. Investigations were carried out in uniform, even aged mature Norway spruce stands that were severely affected with Sirococcus conigenus. The impact of tree nutrition on the severity of Sirococcus shoot blight was tested in a fertilization experiment. Results indicated that disturbances in tree nutrition, especially lack of magnesium and calcium coupled with enhanced N/Mg and N/Ca ratios—increased susceptibility of mature Norway spruce to Sirococcus shoot blight. Furthermore, there were striking differences concerning Ca and Mg contents in green needles between trees on the fertilized and the control plot. Nutrient deficiencies were also found on non-affected unfertilized trees but nutrition was most unfavorable for Sirococcus damaged trees on the control plot. The application of a magnesite derived fertilizer amended with organic compounds balanced tree nutrition and mitigated severity of Sirococcus shoot blight. Terrestrial inventories indicated that intensity of the disease was highest on west exposed upper slopes as well as on hilltops. Stands of different age classes were severely affected by the disease.

The Integrated and Combined (I&C) evaluation system to detect status and trends of the CONECOFOR Permanent Monitoring Plots

CONECOFOR is the Italian program for the intensive monitoring of forest ecosystems sponsored by the Ministry for Agricultural and Forest Policy and the European Commission. It is based upon a series of investigations carried out on 20 (27 from 1999) plots located throughout Italy. The investigations collect data on various ecosystem compartments (soil, ground vegetation, trees, atmosphere) and processes (atmospheric inputs, tree nutrition and growth). A major benefit of intensive monitoring programs is the opportunity they provide to organize integrated studies aimed at understanding the driving forces acting at the ecosystem level. In Italy, the Integrated and Combined (I&amp;C) evaluation system within the CONECOFOR program involves three major approaches: (i) the evaluation of risk status in relation to air pollution, (ii) the quantification of the ecosystem’s status and changes, and (iii) the evaluation of the relationship between pressure and status indicators through time. The I&amp;C project involves scientists from many institutions; major emphasis is placed on the evaluation of data quality and precision. These are regarded as the basic steps in the whole project and a likely source of information about the suitability of the current sample sizes for providing a proper estimation of the parameters under consideration. The paper will provide information on the conceptual and methodological background of the I&amp;C project

Increased boron concentrations of Scots pine foliage induced by green pruning

The responses of Scots pine (Pinus sylvestris L.) foliar boron (B) concentrations to artificial defoliation by green pruning were studied by examining sample trees for 3 years after the treatments. In winter, concentrations of boron in foliage were determined individually from needles on the lateral top shoots of 168 sample trees (at the beginning 2–8 m, at the end 4–10 m tall). To prevent the pruning residues from affecting the nutrition of the sample trees, all pruned branches were transported away from the research area. Before pruning, there were no differences in foliar B among the pruning classes. Reduction of the living crown by pruning (LCRP, % of the initial crown ratio) 50% or more increased the concentrations of foliar B drastically for 3 years. The increase was greatest in the largest trees with the highest LCRP (about 70%), where the mean concentrations of foliar B one year after pruning were nearly 180% higher than in the unpruned trees. Pruning of the dead branch whorls or only the few lowest living whorls did not affect the boron nutrition of the trees. In the current study, the ability of rapid and sufficiently large defoliation to increase B concentrations for several years in the Scots pine foliage was confirmed experimentally; earlier suggestions have been based on analyses made after defoliation. The potential suitability of green pruning is discussed as a method for improving the boron status of trees in boron-deficient areas.

MINERAL NUTRITION, GROWTH AND YIELDS OF ANNATTO TREES (BIXA ORELLANA) IN AGROFORESTRY ON AN AMAZONIAN FERRALSOL

Permanent tree crop agriculture and multi-strata agroforestry are among the most promising options for the agricultural use of the mostly nutrient-poor and physically fragile soils of central Amazonia. In general, though, information on the optimum management of local tree crops under these conditions is inadequate. Annatto (Bixa orellana) is a small tree of tropical American origin whose seeds contain a non-toxic, carotenoid dye that is used widely in food and cosmetic products. The authors studied seed yields at ages four to seven years, biomass at seven years, nutrient accumulation and mineral nutrition of annatto trees growing in multi-strata agroforestry with different inputs of fertilizer and lime on a xanthic Ferralsol in central Amazonia. Leaf samples of three age classes were collected four times during one year, and nutrient concentrations were related to soil nutrient status, growth and yield of the trees in order to develop an optimum sampling scheme for foliar analysis. Growth and yields of the trees showed a pronounced response to increased fertilizer and lime input, which seemed to be due mainly to improved availability of phosphorus. Nitrogen fertilizer had no effect and may not be necessary for well-established trees on this soil. High litter quality and substantial nutrient recycling with annual pruning make annatto a valuable component for agroforestry systems. In this experiment, however, yields were low and decreased after the fifth year, presumably as an effect of infertile soil, shading by larger trees and, possibly, a negative effect of the drastic annual pruning with removal of the entire leaf and small-branch biomass on the vitality of the trees. Annatto is probably best suited for associations with small tree crops. Less drastic pruning treatments than those practiced in this experiment may be preferable.

Lodgepole pine nutrition and growth on grazed forest cutblocks in southern British Columbia

Forest grazing occurs on replanted or naturally regenerated cutblocks, giving temporary grazing opportunities for British Columbia's beef industry. However, grazing on forest cutblocks sometimes results in conflicts between the different interests of the timber and ranching industries. The forester's primary concern about cattle grazing and forage seeding on cutblocks is tree damage by trampling and browsing, followed by soil compaction and altered tree nutrition. This study evaluated the effect of long-term cattle grazing and forage seeding on growth and nutrition of lodgepole pine on three grazed forest cutblocks near Kamloops and Merritt, B.C.Grazing regimes consisted of ungrazed exclosures and pastures grazed at 50% forage utilization during 1989–1998. Forage seeding treatments were 0 and 12 kg/ha. Tree measurements and foliage samples were obtained in September 1999. Tree height, current-year growth (length of leader internode), and foliar nutrient levels of regenerating lodgepole pine have not been significantly affected by forage seeding rate and 9 years of cattle grazing. The absence of significant effects on tree growth and nutrition is particularly noteworthy because of the marginal or somewhat deficient status of several nutrients (N, P, B, Fe, and Cu) on these study sites.The management implications of this study relate to the benign effects of 9 years of cattle grazing on lodgepole pine nutrition and growth. The study provides evidence that cattle grazing is compatible with forestry. These results support the integrated use of forested rangelands in southern British Columbia. Attempting to extrapolate these findings to other site conditions should be done with caution.

Organic Citrus: Soil Fertility and Plant Nutrition

ABSTRACT Increasing realization of the ill effects of long sustained, exclusive use of chemical fertilizers, and consistent growing demand from the consumers for fruit quality, coupled with unsustainable productivity of citrus, have fostered experimentation with some alternative cultural practices. Organic culture is claimed to be the most benign alternative. Use of organic materials such as farmyard manure, cakes of plant origin, vermicompost, and microbial bio-fertilizers on one hand, and exploiting the synergism between citrus-vesicular arbuscular mycorrhizal fungus on the other hand, are important components of the bio-organic concept of citrus cultivation. Mycorrhizae were observed to be highly effective in low fertility, coarse textured soils. Mycorrhizal-treated trees had better plant growth and uptake of nutrients like P, Ca, Zn, Cu, and Fe compared to non-mycorrhizal trees. Inoculation of soil with mycorrhizae also helped in regulating the water relations and carbohydrate metabolism of citrus trees. Phosphorus nutrition of mycorrhizal-treated citrus trees was best improved by using rock phosphate as a source of P as opposed to other sources.

Foliar Nutrient Contents in Tree Species of the Atlantic Rain Forest as Influenced by Air Pollution from the Industrial Complex of Cubatão, SE-Brazil

Air pollutant emissions from the industrial complex of Cubatao, SE-Brazil, have caused a severe decline of the Atlantic Forest in that region. In order to test the influenceof air pollution on the mineral nutrition of trees, leaves of the native species Tibouchina pulchra Cogn. (Melastomataceae), Miconia pyrifolia Naud. (Melastomataceae) and Cecropia glazioui Snethl. (Cecropiaceae) were sampled during winter and summer seasons at four sites with different pollution characteristics. Additionally, saplings of T. pulchra were cultivated in uniform soil and exposed to ambient air at the same experimentalsites for periods of 16 weeks. In both kinds of leaf samples, the concentrations of macro-nutrients were determined and nutrient ratios calculated. In leaves of mature T. pulchraand C. glazioui growing at polluted sites N, P and S levels were significantly higher than in trees from the reference area. With respect to K contents, C. glaziouishowed an increase, T. pulchra a decrease when compared to reference trees. Mg and Ca concentrations generally did not exhibit great variations. As a consequence of the changes in mineral contents nutrient ratios (N/K, N/Ca, S/K, S/Ca) shifted to higher values. The results of the exposure experiments together with data on pollutant concentrations inambient air and rain water demonstrated that atmosphericdeposition to the plants and pollution effects on the soilchemistry are the main reasons for the observed alterations inmineral nutrition of trees.

Air pollution and environmental chemistry – what role for tree-ring studies?

Summary Tree-rings are a unique source of long-term data and have often been used in studies aimed at understanding and quantifying the impact of air pollution on forests. A variety of approaches have been used, ranging from traditional dendrochronology to studies focussing on the chemical and physical properties of tree-rings. However, there are some issues to be considered when attempting to use tree-rings as a response indicator in air pollution studies and when inferences over large geographical scales are being made. These issues include the inherent ambiguity of tree-ring width as indicator of air pollution effects, the absence of reference data, the problems associated with integrating traditional dendrochronology with more complex ecosystem studies and the relatively poor attention paid to sound statistical design in some air pollution impact studies. Together with progress in specific disciplines like climatology, biochemistry, genetics, tree physiology, tree nutrition and soil science, the interdisciplinary and international collaboration in the analysis of environmental effects on tree growth will increase the research potential of tree-rings.

Do admixed broadleaves improve foliar nutrient status of conifer tree crops?

We investigated three Douglas fir–red alder stands in Oregon, USA, and five Norway spruce–European beech stands in Bavaria, Germany, to test the hypothesis that admixtures of broadleaved trees improve nutritional status of conifers. At each site needle samples from 20 to 30 conifer trees with varying proportions of broadleaves adjacent to the sample trees were taken and analysed for needle mass and the macronutrients N, P, K, Ca and Mg. The neighbourhood of each tree was described by the proportion of deciduous basal area within an 8 m circle. Ordination methods (principal component analysis; redundancy analysis) were used to test the dependency of the multivariate nutritional pattern in conifers on deciduous neighbours and rank correlation and regression were used to analyse bivariate relationships between tree species composition and descriptors of needle status. The statistical analyses yielded no evidence that deciduous admixtures improve foliar nutrition of conifers. Alongside with other empirical studies this shows that beneficial effects of broadleave admixtures on conifer nutrition are less common than postulated. Future research investigating the whole causal path relevant for tree nutrition and growth is necessary to improve our knowledge in the complex field of nutrition of mixed species forests.

Organic fruit production in Switzerland: Research and development to resolve cultural, management, and marketing problems

AbstractThe area devoted to organic table fruit production in Switzerland remained virtually unchanged from the 1930s to the mid-1980s. However, during the last decade there has been a fivefold increase in the production area, approaching a total of 340 ha in 2000 (4.8% of the total area of table fruit production). Factors contributing to this dramatic increase include (1) new and effective non-chemical methods for pest and disease control, (2) improved management and production techniques from research and extension programs, (3) increased marketing of organic produce by supermarkets due to consumer demand, and (4) change in Swiss government policy that began to subsidize ecological performance rather than farm production. A 1994 poll of consumer demand indicated that 3 to 5% of the total apples marketed in Switzerland was organically grown, and projected a total market share of 10% in the near future. Despite this, conventional fruit growers are hesitant to convert to organic production methods because of certain risks involving (1) selection of varieties, (2) pest and disease control, (3) crop hectarage controls, (4) weed control, and (5) tree nutrition. Research and development programs are attempting to deal with these problems, to reduce the level of risk with organic production. Nevertheless, ecological considerations to optimize fruit production are strongly dictated by market conditions and consumer demand. Finally, the development of a stable organic fruit production sector will require that retailers and supermarkets make certain concessions for marketing organic fruit.

Identification of genes for lignin peroxidases and manganese peroxidases in ectomycorrhizal fungi.

• Genes for ligninolytic enzymes, normally associated with white-rot fungi, are shown to be widespread in a broad taxonomic range of ectomycorrhizal (ECM) fungi. • ECM fungi were screened for lignin peroxidase (LiP) and manganese peroxidase (MnP) genes by PCR using primers specific for known isozymes in the white-rot fungus Phanerochaete chrysosporium, with DNA sequencing used to confirm the identity of the amplified fragments. • Genes for LiPs were detected in ECM fungi representing the orders Agaricales, Aphyllophorales, Boletales, Cantharellales, Hymenochaetales, Sclerodermatales, Stereales and Thelephorales. MnP genes were detected in only Cortinarius rotundisporus and three ECM Stereales taxa. • The presence of genes for decomposer activities supports putative evolutionary relationships between ECM and saprotrophic fungi. Expression of the lignolytic genes may facilitate ECM fungal access to nutrients associated with dead plant material in soil and potentially a supplementary carbon supply. Strict functional boundaries between ECM and decomposer fungi may be less clear-cut than previously thought.

Molecular characterization of two ammonium transporters from the ectomycorrhizal fungus Hebeloma cylindrosporum

Heterologous expression of the yeast triple Mep mutant has enabled the first molecular characterization of AMT/MEP family members in an ectomycorrhizal fungus. External hyphae, which play a key role in nitrogen nutrition of trees, are considered as the absorbing structure of the ectomycorrhizal symbiosis and therefore molecular studies on ammonium transport in hyphae are urgently needed. The kinetic properties of AMT2 and AMT3 from Hebeloma cylindrosporum were studied in Saccharomyces cerevisiae. Expression of HcAmts in the yeast triple Mep mutant restored ammonium retention within cells. The HcAmts did not complement the ammonium sensing defect phenotype of Mep2Δ cells during pseudohyphal differentiation. Northern blot analysis in H. cylindrosporum showed that the HcAMTs were up-regulated upon nitrogen deprivation and down-regulated by ammonium.

Mycorhization contrôlée et fertilisation phosphatée : applications à la domestication du jujubier

Introduction. Le jujubier, Zizyphus mauritiana Lam., est un arbre fruitier forestier tres recherche pour ses fruits par les populations du Sahel. La domestication de cette espece a ete abordee a partir de techniques sylvicoles comme la mycorhization controlee et la fertilisation phosphatee avec des phosphates naturels (PN). Le document presente une synthese des resultats acquis sur ces sujets. Materiel et methodes. La dependance mycorhizienne du jujubier et de douze autres especes d'arbres fruitiers forestiers vis-a-vis de deux champignons mycorhiziens a arbuscules Glomus aggregatum et G. intraradices a ete etudiee. Par ailleurs, la capacite de l'arbre a mobiliser du phosphore a partir de PN d'Afrique de l'Ouest a ete evaluee dans un sol sableux, pauvre en phosphore assimilable et a pH faiblement acide. Des jujubiers inocules avec G. aggregatum ont ete ensuite mis au champ afin de suivre des parametres de croissance. Resultats et discussion. Parmi les treize especes d'arbres fruitiers forestiers etudies, le jujubier s'est revele etre le plus dependant de la symbiose mycorhizienne avec G. aggregatum qui agit sur sa croissance et son alimentation en phosphore assimilable. Les jujubiers mycorhizes mobilisent plus efficacement le phosphore des PN de Tilemsi (Mali) que celui des PN de Taiba (Senegal) et de Kodjari (Burkina Faso). En pepinieres, la mycorhization controlee a des effets benefiques sur la croissance de jujubiers de differentes provenances. Cet effet benefique de l'inoculation a aussi ete observe en plantation sur des arbres de 20 mois. Conclusion. Les techniques de mycorhization controlee et de fertilisation avec des PN sont aptes a ameliorer la croissance et la nutrition phosphatee des jujubiers en pepinieres et au champ. Cependant, elles devront etre testees dans d'autres sites forestiers afin d'evaluer leurs effets sur la production fourragere et fruitiere des jujubiers.

Sulfur nutrition of deciduous trees.

Sulfur in its reduced form (-II) is an essential nutrient for growth and development, but is mainly available to plants in its oxidised form as sulfate. Deciduous trees take up sulfate by the roots from the soil solution and reduce sulfate to sulfide via assimilatory sulfate reduction in both roots and leaves. For reduction in the leaves, sulfate is loaded into the xylem and transported to the shoot. The surplus of sulfate not reduced in the chloroplast or stored in the vacuole and the surplus of reduced S not used for protein synthesis in the leaves is loaded into the phloem and transported back to the roots. Along the transport path, sulfate and glutathione (GSH) is unloaded from the phloem for storage in xylem and phloem parenchyma as well as in pit and ray cells. Remobilised S from storage tissues is loaded into the xylem during spring, but a phloem to xylem exchange does not appear to exist later in the season. As a consequence, a cycling pool of S was only found during the change of the seasons. The sulfate:glutathione ratio in the phloem seems to be involved in the regulation of S nutrition. This picture of S nutrition is discussed in relation to the different growth patterns of deciduous trees from the temperate climate zone, i.e. (1) terminated, (2) periodic and (3) indeterminate growth patterns, and in relation to environmental changes.

Response of radiata pine forests to residue management and fertilisation across a fertility gradient in New Zealand

New Zealand law requires sustainable forest management. International definitions of sustainability typically include maintaining the productive capacity of forest soils, and decision tools are needed for managing harvesting and site preparation practices. Trials were established between 1986 and 1994 in different physiographic regions of New Zealand to determine the effects of management on the second-rotation performance of Pinus radiata. Main harvesting and residue treatments at three North Island sites include: whole-tree harvest plus forest floor removal, whole-tree harvest, and stem-only harvest retaining a single layer of slash. These treatments were installed in a random block split-plot design (with and without fertiliser). Additional treatments were added at specific sites (e.g., double slash addition at Woodhill; topsoil removal at Tarawera) to test hypotheses that harvesting intensity is negatively correlated with second-rotation growth, that inadequate nutrition is the reason for the negative correlation, and that fertiliser additions can compensate for the negative impact of harvesting on nutrition. Stands were thinned-to-waste to reduce stocking by 50% at Woodhill (age 7 years), Tarawera and Kinleith (age 5 years). On recent coastal sand dunes at Woodhill, foliar analyses suggest that nutrient availability to trees of N, P, K, B, Mn, and Zn were reduced during critical periods of stand establishment by forest floor removal, and improved by retention of thinning slash. Diameter at 5 years declined as forest floor C:N ratio increased. Diameter after 11 years was reduced by forest floor removal, and positively related with residue retention. On approximately 100-year-old basaltic tephra gravel at Tarawera, foliar concentrations of K and B were positively related with slash and soil nutrient retention, however, the effect of harvest removals on tree nutrition and growth was substantially less than observed on recent sand dunes due to greater native fertility of basaltic gravel. Forest floor C:N ratio at Tarawera explained less variation in tree growth than at Woodhill. On the N-rich Taupo sandy loam of Kinleith Forest, there was no correlation between forest floor C:N ratio and tree diameter to age 5 years. Fertiliser additions have increased tree diameter at all sites, and can ameliorate harvesting-related reductions in growth. However, fertiliser additions caused significant reductions in foliar concentrations of most nutrients studied except N. These trials have been useful for identifying the benefits of residue retention among sites with varying levels of native fertility. Based on the results of this study, we recommend organic matter retention during harvest and site preparation on N-deficient sites such as Pinaki Typic Sandy Recent Soil.