Physico-chemical properties of soils associated with logged forest and areas converted to teak (Tectana grandis Linn. F)

This rapid and extensive introduction of teak to satisfy a predicted wood shortage in Ghana has given rise to the question of the short/long-term effects that management of teak plantations might have on soil properties. No research data is currently available to answer this question

Characterizing fertility targets and multi-element interactions in nursery culture of Quercus rubra seedlings

We quantified and characterized fertility targets for nursery culture of container northern red oak (Quercus rubra L.) seedlings. Plants were supplied with a 15N-5P2O5-15K2O fertilizer at eight rates ranging from 0–150 mg N plant–1 and reared for 18 wk in a greenhouse. Plant growth and nutritional response to increased fertilization followed a curvilinear pattern depicting phases that ranged from deficiency to toxicity. Seedling dry mass production was maximized at sufficiency (25 mg N plant–1 season–1) while optimum N and P uptake occurred at 100 mg N plant–1 season–1. The 150 mg N plant–1 seasonal dose rate induced N and P toxicity, but resulted in antagonistic K interaction. Nutrient loading raised plant N and P contents by 27 and 55%. This new approach demonstrates promise to help refine fertility targets for nursery production of Q. rubra planting stock and may have application to other hardwood species or cultural systems.Caractérisation des objectifs de fertilité et des interactions multiéléments chez des semis de Quercus rubra cultivés en pépinière. Des objectifs de fertilité ont été quantifiés et caractérisés pour des semis de chêne rouge d’Amérique (Quercus rubra L.) cultivés en pépinière. Les semis ont été alimentés avec un engrais 15N-5P2O5-15K2O selon huit taux de 0–150 mg N plant–1 et ont poussés pendant 18 semaines dans une serre. La croissance des semis, leur réponse nutritionnelle à un accroissement de la fertilisation a suivi un modèle curvilinéaire décrivant des phases rangées depuis la carence jusqu’à la toxicité. La production en matière sèche des semis a été maximale à la dose suffisante correspondant à 25 mg N plant–1 saison–1, tandis que l’optimum de consommation s’est situé à 100 mg N plant–1 saison–1. La dose saisonnière de 150 mg N plant–1a induit une toxicité N et P, mais il en est résulté une interaction antagoniste avec K. Le prélèvement de nutriments par les plants a augmenté le contenu en N et P de 27 % et 55 %. Cette nouvelle approche démontre la possibilité d’espérer perfectionner les objectifs de fertilité pour une production en pépinière de plants de Quercus rubra et peuvent avoir une application pour d’autres espèces feuillues et d’autres systèmes culturaux

Drought susceptibility and recovery of transplanted Quercus rubra seedlings in relation to root system morphology

•  Transplant shock, implicated by depressed seedling physiological status associated with moisture stress immediately following planting, limits early plantation establishment. Large root volume $(Rv)$ has potential to alleviate transplant shock because of higher root growth potential and greater access to soil water. • We investigated impacts of drought and transplant $Rv$ on photosynthetic assimilation ($A$), transpiration ($E$), stomatal conductance $(g_{\rm s})$, predawn leaf xylem water potential $(\Psi _{\rm L})$, and growth of northern red oak (Quercus rubra L.) seedlings to explain mechanisms associated with susceptibility to transplant shock. One year-old barerooot seedlings were graded into four $Rv$ categories and either well watered or subjected to drought consisting of low, medium, or high moisture stress by discontinuing irrigation at 22-day intervals for 3 months. Thereafter, all treatments were re-watered to examine recovery. • Transplant shock was signified by reduced $A$, $E$, $g_{\rm s}$, and $\Psi _{\rm L}$, which generally increased with increasing moisture stress and $Rv$. Physiological status improved during recovery, though stress was still evident in seedlings exposed to medium or high moisture stress and in larger $Rv$ seedlings. Growth declined with increasing moisture stress but was generally similar among $Rv$ treatments, likely reflecting greater $A$ at the whole plant level and/or reliance upon stored reserves in large $Rv$ seedlings. • The most effective drought avoidance mechanisms were root growth, stomatal regulation, reduced leaf area, and higher growth allocation to roots relative to shoots. Our results suggest that large initial $Rv$ does not enhance drought avoidance during the first season after transplant in northern red oak seedlings.Sensibilité à la sécheresse et reprise des semis transplantés de Quercus rubra en relation avec la morphologie racinaire. • Le choc de transplantation, lié à l'état physiologique déprimé des plants associé à un stress hydrique, immédiatement après la plantation, limite le début de l'installation des plants. Un important volume racinaire ($Rv$) a le potentiel d'atténuer le choc de transplantation en raison du fort potentiel de croissance racinaire et d'un meilleur accès à l'eau du sol. Nous avons étudié les impacts de la sécheresse et des transplants $Rv$ sur l'assimilation photosynthétique ($A$), la transpiration ($E$), la conductance stomatique $(g_{\rm s})$, le potentiel hydrique de base $(\Psi _{\rm L})$, et la croissance des plants de chêne rouge (Quercus rubra L.) pour expliquer les mécanismes associés à la sensibilité à un choc de transplantation. Des plants de un an à racines nues ont été classés en quatre catégories $Rv$ et soit bien arrosés, ou soumis à une sécheresse, consistant à un faible, moyen ou fort stress hydrique en cessant l'irrigation à 22 jours d'intervalle(27, 49 et 72 après la transplantation) pour 3 mois. Par la suite, tous les traitements ont été arrosés afin d'examiner la reprise. • Le choc de transplantation qui généralement a augmenté avec l'augmentation du stress hydrique et $Rv$ , a été significatif par la réduction de $A$, $E$, $g_{\rm s}$, and $\Psi _{\rm L}$. L'état physiologique s'est amélioré lors de la reprise, même si le stress est encore évident chez les plants exposés à un stress hydrique moyen ou élevé et chez les plants à $Rv$ les plus importants. La croissance a diminué avec l'augmentation du stress hydrique, mais elle a été généralement similaire chez les traitements $Rv$, reflétant probablement une plus grande $A$ au niveau du plant entier et / ou le recours à des réserves stockées dans les plants à $Rv$ important. • Les mécanismes d'évitement de la sécheresse les plus efficaces ont été la croissance des racines, la régulation stomatique, une surface foliaire réduite et une allocation de la croissance plus élevée aux racines par rapport aux pousses. Nos résultats suggèrent que les grandes $Rv$ initiales n'améliorent pas l'évitement de la sécheresse durant la première saison après transplantation chez les plants de chêne rouge

Nitrogen Recovery from Enhanced Efficiency Fertilizers and Urea in Intensively Managed Black Walnut (Juglans nigra) Plantations

Intensively managed forest plantations often require fertilization to maintain site fertility and to improve growth and yield over successive rotations. We applied urea-based “enhanced-efficiency fertilizers” (EEF) containing 0.5 atom% 15N at a rate of 224 kg N ha−1 to soils under mid-rotation black walnut (Juglans nigra L.) plantations to track the fate of applied 15N within aboveground ecosystem components during the 12-month period after application. Treatments included Agrotain Ultra (urea coated with a urease inhibitor), Arborite EC (urea coated with water-soluble boron and phosphate), Agrium ESN (polymer-coated urea), uncoated urea, and an unfertilized control. Agrotain Ultra and Arborite EC increased N concentrations of competing vegetation within one month after fertilization, while neither Agrium ESN nor uncoated urea had any effect on competing vegetation N concentrations during the experiment. Agrotain Ultra and Arborite EC increased δ15N values in leaves of crop trees above those of controls at one and two months after fertilization, respectively. By contrast, Agrium ESN and uncoated urea had no effect on δ15N values in leaves of crop trees until three months after fertilization. Fertilizer N recovery (FNR) varied among ecosystem components, with competing vegetation acting as a sink for applied nutrients. There were no significant differences in FNR for all the urea-based EEF products compared to uncoated urea. Agrium ESN was the only EEF that exhibited controlled-release activity in this study, with other fertilizers behaving similarly to uncoated urea

Late-season fertilization of Picea mariana seedlings: intensive loading and outplanting response on greenhouse bioassays

Traditional greenhouse culture involves a late-season hardening period that withholds irrigation and fertilization from black spruce seedlings to promote frost-hardiness. Since nutrient uptake is limited without supplemental fertilization, growth during hardening may lead to internal nutrient dilution, a condition detrimental to field performance of seedlings. We examine whether late-season fertilization, applied as intensive loading, will counter dilution and build up nutrient reserves in seedlings reared conventionally or nutrient loaded before hardening. A mixed NPK fertilizer delivering 0, 12, 24, or, 48 mg N·seedling–1 for 9 weeks after bud set was tested. Root and shoot dry mass increased as much as 104 and 42% during hardening. Seedling biomass, however, was unchanged by late-season fertilization, but N uptake was increased 44–167% signifying induced luxury consumption. Extra K supplementation of treatments averted K dilution in plant tissues often occurring with high N addition. A 13-week outplanting trial on intact soil bioassays retrieved from a boreal site showed that growth and nutrient allocation were significantly enhanced by larger N reserves built up after intensive nutrient loading. About 72–80% of N required for new shoot growth was met from internal cycling, demonstrating the capacity of loading to enhance retranslocation. Intermediate loading (24 mg N) was most effective in promoting N accumulation and outplanting growth of both seedling types. Survival was reduced (30%) only at the highest dose. Study results demonstrate the potential advantage of these practices to improve growth of newly planted seedlings on northern forest sites.Fertilisation tardive de semis de Picea mariana : apport intensif et réponse après plantation en serre d’essais biologiques. Les cultures traditionnelles en serre comportent une période tardive d’endurcissement qui retarde l’irrigation et la fertilisation des semis de Picea mariana pour promouvoir l’endurcissement au froid. Puisque le prélèvement de nutriments est limité sans supplémentation de fertilisation, la croissance pendant la période d’endurcissement peut conduire à une dilution interne des nutriments, une situation préjudiciable pour les performances au champ des plants. Nous avons examiné si la fertilisation tardive, appliquée par des apports massifs peut contrebalancer la dilution et accroître les réserves de nutriments dans les semis élevés conventionnellement ou les nutriments apportés avant l’endurcissement. On a testé un mélange de fertilisant NPK libérant 0,12, 24 ou 48 mg d’azote par semis pendant 9 semaines après le débourrement. Le poids sec des racines et des pousses s’est accru de 104 et 42 % pendant l’endurcissement. Cependant la biomasse des semis a été inchangée par une fertilisation tardive, mais le prélèvement d’azote s’est accru de 44 à 167 %, indiquant une consommation de luxe. Une supplémentation en K évite une dilution en K des tissus, ce qui arrive souvent avec un apport important d’azote. Un essai à 13 semaines sur un sol pour essais biologiques, extrait d’une station boréale, a montré que la croissance et l’allocation des nutriments étaient significativement augmentées par de grandes réserves d’azote accumulé après des apports intensifs de nutriments. Environ 72 à 80 % de N requis pour la croissance des nouvelles pousses provenaient du cycle interne, démontrant l’importance des apports pour augmenter les retranslocations. Un apport intermédiaire (24 mg N) était plus efficace pour promouvoir l’accumulation de N et la croissance des deux types de semis. La survie a été réduite (30 %) seulement pour la plus forte dose. Les résultats de cette étude ont démontré l’avantage potentiel de ces pratiques pour l’amélioration de la croissance des semis dans les stations forestières du Nord

Performance of Nutrient-Loaded Red Oak and White Oak Seedlings on Mine Lands in Southern Indiana

ABS TR ACT Exponential nutrient loading was used to build nutrient reserves in northern red oak (Quercus rubra) and white oak (Q. alba) seedlings during standard bareroot nursery culture at the Vallonia State Nursery, Indiana. Nursery grown seedlings were outplanted the following year onto a mine reclamation site in southern Indiana to evaluate effects of prior nursery treatments on field performance. At the nursery stage, exponential nutrient loading improved plant dry mass production. Nutrient loading increased nitrogen uptake 40% in red oak and 35% in white oak when compared to controls. When outplanted, exponential nutrient loading enhanced shoot height and root collar diameter response in the studied species. White oak seedling survival was 92%, compared with 83% for red oak in year 1. Survival decreased to about 74% for white oak and 65% for red oak in year 2. Results suggest exponential nutrient loading has potential to promote seedling performance on harsh site conditions, and are significant for reclamation efforts in Indiana and across the US. Fertilization at planting, in combination with weed control with herbicides, can alleviate poor site fertility, reduce competition, and enhance seedling field survival and growth (Jacobs and others 2005). However, there is public sentiment against herbicide use in forests owing to potential negative impacts on the environment and on biodiversity KEYWORDS Several fertilization methods, such as conventional, exponential, or nutrient-loading models, can be used to nutritionally pre-condition plants at the nursery stage for outplanting. Conventional fertilization involves application of equal fertilizer doses at regularly spaced intervals throughout the growing season. This approach creates a surplus of nutrients to young seedlings early in the growth phase, but may cause a deficiency in larger seedlings by the end of the growing season Although the above fertilization techniques may have universal application, protocols to determine optimal target rates associated with maximum growth and seedling nutrient storage are not well defined. There is apparent need to quantify target rates for each species and cultural system owing to differences in species demand for nutrients and variations in cultural conditions. An innovative approach that can help rationalize and quantify fertility targets in tree seedling culture is illustrated in USDA Forest Service Proceedings :: RMRS-P-57 :: 2008 67 Nutrient-loaded seedlings exhibit greater survival, growth, and competitiveness over nonloaded plants on a variety of habitats Materials and Methods Nursery Phase Bareroot northern red oak and white oak seedlings were grown from seeds germinated in spring 2004 at Vallonia State Nursery, Indiana (38°85'N, 86°10'W). Seedlings were fertilized conventionally or exponentially using 10 fertility treatments that ranged from deficiency to toxicity (0 to 3.35 g N/plant/season). Higher fertility treatments were intended to build nutrient reserves in plants for later utilization when outplanted. Nitrogen was applied bi-weekly as ammonium nitrate in crystal form (34N:0P 2 O 5 :0K 2 O). Further details on the nursery study can be found in Birge and others (2006). Seedlings were mechanically lifted in December 2004 and processed for overwinter Field Study Nursery-reared seedlings were outplanted in April 2005 into an abandoned mine reclamation site in southern Indiana. The field design was a split-plot design with a 2 x 10 factorial treatment structure, and was replicated in 5 blocks. The main plot treatments were species at 2 levels and the sub-plot treatments were the 10 nursery fertility treatments. Each block measured 21 x 42 m (69 x 138 ft) and was separated from the next by 2-m (6.5-ft) buffers. Species were randomly allocated within blocks, and fertility treatments were randomly allocated within species. Each treatment consisted of 20 trees in one row within a block, and each block contained 20 rows. A total of 2500 seedlings were planted and monitored in this 68 USDA Forest Service Proceedings :: RMRS-P-57 :: 2008 experiment (10 treatments x 20 trees per treatment x 2 species x 5 replications). Trees were planted 1 x 1 m (3.3 x 3.3 ft) within rows and 2 x 2 m (6.5 x 6.5 ft) between rows. Sampling and quantification of seedling morphological and nutritional responses followed standard protocols Results and Discussion Nursery Phase Growth and nutritional data sampled at the end of nursery culture (Birge and others 2006) conformed closely to trends shown in Field Response Generally, field survival was high in year 1 Conclusions Storing nutrients in seedlings at the nursery stage provides a better rationale to promote seedling field performance. Higher pre-plant nutrient reserves have potential to reduce competitive effects and enhance internal redistribution to support new growth soon after outplanting. High survival and growth of competitive nutrientloaded seedlings will accelerate forest restoration success on degraded landscapes, which will help to conserve soil resources as well as provide habi- tat for wildlife. Early rapid growth will allow plants to reach free-to-grow status sooner and minimize potential for animal browse. Use of competitive nutrient-loaded seedlings will accelerate early growth and minimize the need to control competing vegetation with herbicides. The use of balanced fertilizer is key to successful nutrient loading. Frequent and light applications will make nutrients readily available to plants. This increases uptake efficiency and minimizes potential leaching losses associated with heavy and less frequent applications

Growth, physiology, and nutrient retranslocation in nitrogen-15 fertilized Quercus rubra seedlings

We evaluated gas exchange, chlorophyll index (CI) using SPAD-502 chlorophyll meter, and leaf nutritional responses in one-year-old northern red oak (Quercus rubra L.) container seedlings transplanted into control (unfertilized) or fertilized (0.86 g N plant$^{-1})$ sand culture and grown in a greenhouse for 90 days. We labeled current nitrogen (N) uptake with ($^{15}$NH$_{4})_{2}$SO$_{4}$ and directly quantified proportional contributions of N derived from fertilizer (NF) compared with retranslocation or N derived from plant (NP) in leaf growth of red oak seedlings. NF met a greater N demand in leaf growth of fertilized plants while unfertilized seedlings relied entirely on NP for their leaf growth. Fertilization increased leaf dry mass by 67% and new stem dry mass by 253% 90 days after transplanting compared to control seedlings. Specific leaf area (SLA) was not significantly altered but CI increased 90 days after transplanting. Higher leaf N concentration and content in fertilized compared with control seedlings was linked to greater chlorophyll concentrations in the former plants. The higher coefficient of determination ($r$$^{2}$ = 0.72) noted between leaf N concentrations and CI suggests that the SPAD meter could be a useful tool for assessing leaf N status in northern red oak seedlings. Fertilized seedlings exhibited higher net assimilation, stomatal conductance, and transpiration rates compared with controls. Increased seedling growth in response to fertilization was related to maintenance of higher gas exchange and greater nutrient uptake, which could improve outplanting success.Croissance, échanges gazeux et réponses nutritionnelles de jeunes semis de Quercus rubra soumis à une fertilisation par ($^{15}$NH$_{4})_{2}$SO$_{4}$. Nous avons estimé les échanges gazeux foliaires, un index de teneurs en chlorophylles (IC) avec un chlorophylle-mètre SPAD-502 et les teneurs en nutriments dans les feuilles de jeunes plants de chêne rouge d'Amérique (Quercus rubra L.) âgés d'un an. Les plants ont été transplantés dans du substrat sableux non fertilisé (témoins) ou fertilisé avec 0.86 g N par plante, et cultivés pendant 90 jours sous serre. L'azote apporté par la fertilisation était marqué avec ($^{15}$NH$_{4})_{2}$SO$_{4}$ et nous avons directement quantifié les contributions à la croissance foliaire de N apporté par la fertilisation (NF) par rapport à celle de N remobilisé depuis les pools de réserve de la plante (NP). NF constituait la fraction la plus importante d'azote foliaire de plants fertilisés, alors que l'azote foliaire des plants non fertilisés était exclusivement constitué de NP. La fertilisation s'est traduite par une augmentation, par rapport aux plantes témoins, de 67 % de la biomasse foliaire et de 253 % de la biomasse de tiges nouvellement formées 90 jours après la transplantation. La surface spécifique des feuilles n'était pas affectée par la fertilisation alors que CI avait significativement augmenté. Des teneurs plus élevées en N foliaire en comparaison des témoins, étaient donc liées à des concentrations plus fortes en chlorophylles. Le coefficient de détermination élevé ($r$$^{2}$ = 0.72) des relations entre concentration de N et CI montrent que le SPAD-502 pourrait être un instrument utile pour l'évaluation des teneurs en N dans des semis de chêne rouge. Les semis fertilisés présentaient également des niveaux d'assimilation nette de CO$_{2}$, de conductance stomatique et de transpiration plus élevés que les plants témoins. La croissance plus forte des semis en réponse à la fertilisation était liée à des échanges gazeux plus actifs et une plus forte assimilation de nutriments, ce qui peut augmenter les chances de succès à la transplantation en forêt