Species ecology determines the role of nitrogen nutrition on the frost tolerance of pine seedlings

Frost determines the evolution and distribution of plants in temperate and cold regions. Several environmental factors can influencefrost acclimation of woody plants but the magnitude and direction of the effect of nitrogen (N) availability is controversial.We studied the effect of N availability on root and shoot frost tolerance in mid-fall and in winter in seedlings of four pines of contrastingecology: Pinus nigra J.F. Arnold, P. pinaster Ait., P. pinea L. and P. halepensis Mill.. Organ N and soluble sugar concentration,and timing of cessation of shoot elongation were measured to assess the physiological mechanisms underlying frostacclimation. Nitrogen was supplied at high and low rates only during the pre-hardening period and at a moderate N rate duringhardening in the fall. Shoot frost tolerance increased over winter while root frost tolerance did not change in any species. PrehardeningN availability affected the frost tolerance of both roots and shoots, although the effect was species-specific: high Nreduced the overall root and shoot frost tolerance in P. pinea and P. halepensis, and increased the frost tolerance in P. nigra, buthad no effect in P. pinaster. Nitrogen supply in the fall consistently increased frost tolerance in all speciesComunidad de Madri

Root uptake of inorganic and organic N chemical forms in two coexisting Mediterranean forest trees

Background and aims Plants differ in their ability to usedifferent nitrogen (N) chemical forms, these differencescan be related to their ecology and drive communitystructure. The capacity to uptake intact organic N hasbeen observed in plants of several ecosystems. However,soil organic N uptake by Mediterranean plants is unknowndespite organic N being abundant inMediterranean ecosystems. We compare the uptake ofdifferent N forms in two widespread coexistingMediterranean forest trees with contrasting ecophysiologicalcharacteristics: Quercus ilex and Pinus halepensis.Methods To estimate root uptake rate of eachN form weused equimolar solutions (1 mM N) of 15NO3-, 15NH4+ and 15N-13C glycine.Results NH4+ and glycine were taken up at a similarrate, but faster than NO3− in both species. Intact duallabeled glycine was found in both species, demonstratingthat both species can absorb intact organic N. Conclusions: Despite their ecological differences, both species had similar preference for N forms suggesting no niche complementarity for N uptake. The higher preference for NH4 + and glycine over NO3 - possibly reflects adaptation to the differing proportions of N forms in Mediterranean soils.Ministerio de Educación y CienciaMinisterio de Ciencia e InnovaciónMinisterio de Economía y CompetitividadComunidad de Madri

Foliar absorption and root translocation of nitrogen from different chemical forms in seedlings of two Mediterranean trees.

Along with root uptake, plants can also absorb N through leaves. There are few comparative studieson the foliar absorption of N from different chemical forms of N in forest tree species. We comparedthe foliar N absorption capacity in seedlings of two forest trees widespread in the Mediterranean basin,Quercus ilex and Pinus halepensis. Plants were sprayed with the following individual N forms at 40 mMN:15N-nitrate (NO3−),15N-ammonium (NH4+),15N-urea or13C and15N dual-labeled glycine. Cuticularconductance was used as a surrogate of cuticle permeability to water. Q. ilex had higher N foliar absorp-tion than P. hapelensis. Neither cuticular conductance nor shoot surface area explained N differences inabsorption rate between species, which were instead likely linked to differences in stomatal density andpresence of trichomes. In both species, foliar N absorption rate and N recovery differed among N forms:urea > NH4+≥ glycine ≥ NO3−. Differences in N absorption rate among N forms were correlated with theirphysico-chemical properties. The strong positive relationship between15N and13C uptake together withdetection in shoots of intact dual-labeled glycine (measured by gas chromatography&#-mass spectrome-try), indicated that a significant fraction of glycine was absorbed intact by the seedlings. In both species,higher cuticular conductance was related to faster N absorption from all forms except NO3&;8722#. Cuticularconductance had a stronger effect on N absorption from urea and NH4+than N absorption from glycine,and the effects were more intense in Q. ilex than in P. halepensis.Comunidad de MadridAustralian Research Counci

Nitrogen form and concentration interact to affect the performance of two ecologically distinct Mediterranean forest trees

Most studies examining inorganic N formeffects on growth and nutrition of forest trees have beenconducted on single species from boreal or temperateenvironments, while comparative studies with species fromother biomes are scarce. We evaluated the response of twoMediterranean trees of contrasting ecology, Quercus ilex L.and Pinus halepensis Mill., to cultivation with distinctinorganic N forms. Seedlings were fertilized with differentNH4?/NO3- proportion at either 1 or 10 mM N. In bothspecies, N forms had small effects at low N concentration,but at high N concentration they markedly affected theplant performance. A greater proportion of NH4? in thefertilizer at high N caused toxicity as it reduced growth andcaused seedling death, with the effect being greater in Q.ilex than in P. halepensis. An increase in the proportion ofNO3- at high N strongly enhanced growth relative to lowN plants in P. halepensis but had minor effects in Q. ilex.Relatively more NH4? in the fertilizer enhanced plant Pconcentration but reduced K concentration in both species,while the opposite effect occurred with NO3-, and these effects were enhanced under high N concentration. We conclude that species responses to inorganic N forms were related to their ecology. P. halepensis, a pioneer tree, had improved performance with NO3 - at high N concentration and showed strong plasticity to changes in N supply. Q. ilex, a late successional tree, had low responsiveness to N form or concentration.Ministerio de Educación y CulturaMinisterio de Ciencia e InnovaciónComunidad de Madri

How can my research paper be useful for future meta-analyses on forest restoration plantations?

Statistical meta-analysis is a powerful and useful tool to quantitatively synthesizethe information conveyed in published studies on a particular topic. It allows identifyingand quantifying overall patterns and exploring causes of variation. The inclusion ofpublished works in meta-analyses requires, however, a minimum quality standard of thereported data and information on the methodology used. Our experience with conductinga meta-analysis on the relationship between seedling quality and field performance is thatnearly one third of the apparently relevant publications had to be discarded because essentialdata, usually statistical dispersion parameters, were not properly reported. In addition,we encountered substantial difficulty to explore the effect of covariates due to the poordescription of nursery cultivation methods, plantation location, and management in a significantproportion of the selected primary studies. Thus, we present guidelines for improvingmethodology detail and data presentation so that future forest restoration-orientedresearch can be more readily incorporated into meta-analyses. In general, research studiesshould report data on means, sample size, and any measure of variation even if they arenot statistically significantComunidad de MadridMinisterio de Economí

Fertilization regime interacts with fall temperature in the nursery to determine the frost and drought tolerance and nutrient status of the Mediterranean oak Quercus ilex L.

Nitrogen fertilization in the nursery usually improves the transplanting performance of Mediterraneanoaks. However, high N fertilization can reduce seedling stress tolerance, probably depending on the environmentalconditions under which plants grow. We hypothesize that high N fertilization under mild fallconditions reduces cold and drought acclimation. To assess this hypothesis, we studied if fall temperaturedifferences among cultivation locations influence the effect of N fertilization regime on cold and droughttolerance, N status and growth in the evergreen Mediterranean oak Quercus ilex subsp. ballota (Desf.) Samp.Plants were cultivated in two nurseries of distinct fall temperature conditions (mild and cold fall nurseries)under four fertilization regimes: Low and highNat constant rate (total N, 33 and 175 mg seedling 1), highNat exponential rate (175 mg N seedling 1) and fallNloading (89 mg N seedling 1). Seedling water relations,survival to a 12 C frost and leaf soluble carbohydrates concentration were assessed three times in the fall,and shoot elongation was measured weekly through the fall. Moreover, seedling mass and N concentrationwere measured at the end of the fall. Fall loaded seedlings had the highest tissue N concentration, whileseedling mass was highest in the highNconstant and exponential fertilization regimes. Seedlings at the coldfall nursery concentrated moreNbut were smaller than seedlings at the mild fall nursery.Ministerio de Ciencia, Innovación y UniversidadesComunidad de Madri

Integración vertical de un proyecto de diseño en el Grado en Ingeniería Química

Depto. de Ingeniería Química y de MaterialesFac. de Ciencias QuímicasFALSEsubmitte