Foliar Chemical Composition Research Articles

Foliar chemical composition and respiration rates of sugar maple (Acer saccharum) and American beech (Fagus grandifolia) trees across a gradient of soil acidification

Foliar chemical composition and respiration rates of sugar maple (Acer saccharum) and American beech (Fagus grandifolia) trees across a gradient of soil acidification

Growth and chemical composition of silver birch: Comparative study between Lithuania and Romania

The effects of different climatic conditions on growth and chemical composition of Betula pendula in geographically different European regions, Lithuania and Romania, were compared. Birch species in the entire area have a wide natural distribution, but B. pendula is commercially more important in Lithuania than in Romania. Here we evaluated tree ring width, wood density and foliar chemical composition of mature birch trees in two European regions. Trees at the Lithuanian sites had greater radial growth and wood density with no clear changes in foliar chemistry than those at the Romanian sites. Mean wood density was 600–700 kg m−3 at Lithuanian and 350–450 kg m−3 at Romanian sites. Mean width of wood ring, earlywood and latewood for Lithuanian birch trees were several times higher than the means for Romanian birch trees. We hypothesized that the main differences in birch radial growth and wood density were due to the different climatic conditions in the studied regions. Ca, K and Mg concentrations were significantly higher and Fe and Mn were lower in the birch foliage at the Lithuanian sites compared those at the Romanian sites. Overall assessment of growth showed that silver birch cultivation is more appropriate for colder climate regions and that birch growth may change in the context of a warming climate.

Nitrogen rate and source effects on foliar sugar, glycoalkaloid, and amino acid composition of potato Russet Burbank

The foliar chemicals in potatoes (Solanum tuberosum L.) could affect the growth and development of agricultural pests, such as Colorado potato beetle Leptinotarsa decemlineata (Say) and aphid Macrosiphum euphorbiae (Thomas). Thus, altering the chemical composition of potato leaves could potentially supplement integrated pest management (IPM). In this study, field experiments were conducted in Quebec, Canada, to investigate the effects of nitrogen (N) rate and source on foliar sugar, glycoalkaloid, and amino acid concentrations and tuber yield of potato cultivar Russet Burbank. Three N fertilizer sources of ammonium nitrate, ammonium sulfate, and polymer-coated urea were used at four rates of 60, 120, 200, and 280 kg N ha−1 plus an unfertilized control in a randomized complete block design. The fourth leaves from the top of 20 randomly selected plants in each plot were collected at 54, 68, and 82 d after planting for sugar, glycoalkaloid, and amino acid analysis. Tubers were collected at harvest, and the total and marketable yields were determined. Results showed that N fertilization linearly decreased sugar concentrations and these reduced sugars were conveyed and stored in tubers as starch. Glycoalkaloid concentrations in leaves were influenced by N source and rate. Both total and marketable yields quadratically varied with increasing N rates regardless of N sources, with average values of 36.4 and 28.3 Mg ha−1, respectively. As N rate affected potato foliar chemical composition and tuber yield, N fertilization could be considered as a supplemental tool to the IPM strategy for potato pest control.

Multivariate interpretation of the foliar chemical composition of essential nutrients in mango under Peninsular India

The nutrient concentration vs yield performance data bank was established for Alphonso mango grownin Peninsular India to develop multivariate diagnostic norms with high diagnostic sensitivity. Well performingorchards in Ramanagara, Srinivaspur, Chittoor, Krishnagiri, Vengurla and Ratnagiri regions were intensivelysurveyed to develop the data bank. The diagnostic norms for N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, b and Mo weredeveloped by using compositional nutrient diagnosis (CND) technique. The interactions among different nutrients were elucidated by principal component analysis (PCA). It was evident that wide variation in plant nutrientconcentration exists in different geographic locations. The mean N concentration showed wide variations from1.03% to 2.87%, P from 0.09 to 0.33% and that of K from 0.78 to 1.35% depending upon the geographic location. Among the micronutrients, Zn concentration showed variation from 14.01 to 24.97 mg kg−1 and b from 3.50 to 16.63 mg kg−1. The CND norms showed higher diagnostic precision compared to the bivariate techniques. Theapplication of PCA indicated that as many as eight nutrient elements were found integrated with first principal component in many locations. Involvement of several nutrients in a single principal component indicated thatit was not possible to diagnose nutrient imbalance of any particular nutrient in isolation in mango and multinutrient involvement on governing yield potential. The extent to which a particular nutrient interacting with other nutrients was a function of nutrient in question and geographic location. The nutrient interaction observed fordifferent locations in general mimicked nutrient behaviour reported earlier. There is a need for integration of the all nutrients for diagnosis of nutrient imbalance in high performing fruit crop like mango.

Schima superba outperforms other tree species by changing foliar chemical composition and shortening construction payback time when facilitated by shrubs.

A 3.5-year field experiment was conducted in a subtropical degraded shrubland to assess how a nurse plant, the native shrub Rhodomyrtus tomentosa, affects the growth of the target trees Pinus elliottii, Schima superba, Castanopsis fissa, and Michelia macclurei, and to probe the intrinsic mechanisms from leaf chemical composition, construction cost (CC), and payback time aspects. We compared tree seedlings grown nearby shrub canopy (canopy subplots, CS) and in open space (open subplots, OS). S. superba in CS showed greater growth, while P. elliottii and M. macclurei were lower when compared to the plants grown in the OS. The reduced levels of high-cost compounds (proteins) and increased levels of low-cost compounds (organic acids) caused reduced CC values for P. elliottii growing in CS. While, the levels of both low-cost minerals and high-cost proteins increased in CS such that CC values of S. superba were similar in OS and CS. Based on maximum photosynthetic rates, P. elliottii required a longer payback time to construct required carbon in canopy than in OS, but the opposite was true for S. superba. The information from this study can be used to evaluate the potential of different tree species in the reforestation of subtropical degraded shrublands.

Foliar chemical composition of two oak species grown in a free-air enrichment system with elevated O<sub>3</sub> and CO<sub>2</sub>

Foliar chemical composition of two oak species grown in a free-air enrichment system with elevated O<sub>3</sub> and CO<sub>2</sub>

Alteration of Microbial Communities Colonizing Leaf Litter in a Temperate Woodland Stream by Growth of Trees under Conditions of Elevated Atmospheric CO 2

Elevated atmospheric CO(2) can cause increased carbon fixation and altered foliar chemical composition in a variety of plants, which has the potential to impact forested headwater streams because they are detritus-based ecosystems that rely on leaf litter as their primary source of organic carbon. Fungi and bacteria play key roles in the entry of terrestrial carbon into aquatic food webs, as they decompose leaf litter and serve as a source of nutrition for invertebrate consumers. This study tested the hypothesis that changes in leaf chemistry caused by elevated atmospheric CO(2) would result in changes in the size and composition of microbial communities colonizing leaves in a woodland stream. Three tree species, Populus tremuloides, Salix alba, and Acer saccharum, were grown under ambient (360 ppm) or elevated (720 ppm) CO(2), and their leaves were incubated in a woodland stream. Elevated-CO(2) treatment resulted in significant increases in the phenolic and tannin contents and C/N ratios of leaves. Microbial effects, which occurred only for P. tremuloides leaves, included decreased fungal biomass and decreased bacterial counts. Analysis of fungal and bacterial communities on P. tremuloides leaves via terminal restriction fragment length polymorphism (T-RFLP) and clone library sequencing revealed that fungal community composition was mostly unchanged by the elevated-CO(2) treatment, whereas bacterial communities showed a significant shift in composition and a significant increase in diversity. Specific changes in bacterial communities included increased numbers of alphaproteobacterial and cytophaga-flavobacter-bacteroides (CFB) group sequences and decreased numbers of betaproteobacterial and firmicutes sequences, as well as a pronounced decrease in overall gram-positive bacterial sequences.

A comparative analysis of foliar chemical composition and leaf construction costs of beech (Fagus sylvatica L.), sycamore maple (Acer pseudoplatanus L.) and ash (Fraxinus excelsior L.) saplings along a light gradient

• Construction cost (g glucose g −1 ), chemical composition and morphology of leaves of beech ( Fagus sylvatica L.) and two co-occurring valuable broadleaved species (sycamore maple – Acer pseudoplatanus L. – and ash – Fraxinus excelsior L.) were investigated along a horizontal light gradient (3–60% of above canopy radiation) and from top to bottom within the crowns in a fairly even-aged mixed-species thicket established by natural regeneration beneath a patchy shelterwood canopy.• Construction cost and carbon concentration increased with irradiance in ash and sycamore maple and were independent of irradiance in beech. Leaf traits expressed on an area basis, like construction cost, nitrogen content and leaf mass (LMA) increased significantly with irradiance in all three species and decreased from top to bottom within crowns.• The shade tolerant beech invested more glucose to produce a unit foliar biomass, but less to build a unit foliar area due to lower LMA. Thereby beech was able to display a greater total leaf area, what at least in parts counterbalanced the lower values of N a as compared to ash and sycamore maple.

Oxidation of Ingested Phenolics in the Tree-Feeding Caterpillar Orgyia leucostigma Depends on Foliar Chemical Composition

Tannins are believed to function as antiherbivore defenses, in part, by acting as prooxidants. However, at the high pH found in the midguts of caterpillars, the oxidative activities of different types of tannins vary tremendously: ellagitannins >> galloyl glucoses > condensed tannins. Ingested ascorbate is utilized by caterpillars to minimize phenolic oxidation in the midgut. Thus, leaves that contain higher levels of reactive tannins and lower levels of ascorbate were hypothesized to produce higher levels of phenolic oxidation in caterpillars. We tested this hypothesis with eight species of deciduous trees by measuring their foliar phenolic and ascorbate compositions and measuring the semiquinone radical (oxidized phenolic) levels formed in caterpillars that ingested each species. When the generalist caterpillars of Orgyia leucostigma (Lymantriidae) fed on the leaves of tree species in which condensed tannins were predominant (i.e., Populus tremuloides, P. deltoides, and Ostrya virginiana), semiquinone radical levels were low or entirely absent from the midgut contents. In contrast, species that contained higher levels of ellagitannins (or galloyl rhamnoses; i.e., Quercus alba, Acer rubrum, and A. saccharum) produced the highest levels of semiquinone radicals in O. leucostigma. Low molecular weight phenolics contributed relatively little to the overall oxidative activities of tree leaves compared with reactive tannins. Ascorbate levels were lowest in the species that also contained the highest levels of oxidatively active tannins, potentially exacerbating phenolic oxidation in the gut lumen. We conclude that the tannin compositions of tree leaves largely determine the effectiveness of foliar phenolics as oxidative defenses against caterpillars such as O. leucostigma.

Análise da composição química foliar do ipê-amarelo (<i>Tabebuia chrysotricha</i> (Mart) Standl) na arborização urbana de Curitiba, PR.

O conhecimento do estado nutricional das árvores urbanas tem uma grande importância para a avaliação e adoção de práticas de manejo. Este trabalho tem como objetivo investigar a composição química foliar da Tabebuia chrysotricha (Mart) Standl no meio urbano. A análise das árvores foi feita em locais com diferentes níveis de poluição e de impermeabilização do canteiro. Com a análise química foliar foi possível constatar que os elementos fósforo (P) e zinco (Zn) diferenciaram os padrões de árvores superiores e inferiores enquanto os elementos cobre (Cu) e zinco (Zn) diferenciaram as condições onde as árvores são plantadas.

Combined Effects of Elevated Co2and Herbivore Damage on Alfalfa and Cotton

We examined herbivore-induced responses of alfalfa (Medicago sativa) and cotton (Gossypium hirsutum) under different CO2 conditions. Plants were grown under ambient (350 ppm) or elevated (700 ppm) CO2 levels, and were either damaged or undamaged by Spodoptera littoralis larvae. At harvest, growth of undamaged (control) plants was determined, and foliar chemical composition of both undamaged and damaged plants was analyzed. Cotton grew faster overall and showed a greater increase in growth in response to CO2 enrichment than did alfalfa. Elevated CO2 levels increased starch and decreased nitrogen levels in damaged alfalfa and undamaged cotton plants. Alfalfa saponin levels were significantly increased by elevated CO2 and damage. Regarding specific saponins, medicagenic acid bidesmoside (3GlcA,28AraRhaXyl medicagenate) concentrations were reduced by high CO2, whereas zanhic acid tridesmoside (3GlcGlcGlc,23Ara,28AraRhaXylApi Za) levels were unaffected by the treatments. Soyasaponin I (3GlcAGalRha soyasapogenol B) was only detected in minute amounts. Alfalfa flavonoid analyses showed that total flavonoid levels were similar between treatments, although free apigenin increased and apigenin glucoside (7-O-[2-O-feruloyl-beta-D-glucuronopyranozyl (1-->2)-O-8-D-glucuronopyranozyl]-4'-O-beta-D-glucuronopyranozide apigenin) decreased in CO2-enriched plants. In cotton, herbivore damage increased levels of total terpenoid aldehydes, gossypol, hemigossypolone, the heliocides H1 and H4, but not H2 and H3, whereas CO2 enrichment had no effect. These results demonstrate that combined effects of CO2 and herbivore damage vary between plant species, which has implications for the competitive balance within plant communities.

Air pollution, global change and forests in the new millennium

Introduction to the Book Series. List of Contributors. Foreword and Acknowledgements. Preface (R.A. Birdsey, USFS Global Change Program). Issues, Challenges and Risks. 1. Air pollution and global change: A double challenge to forest ecosystems (D.F. Karnosky, K.E. Percy et al.). 2. What is the role of demographic factors in air pollution and forests? (D.S. Shriner, D.F. Karnosky). 3. Changing atmospheric carbon dioxide: A threat or benefit? (D.F. Karnosky, P. Sharma et al.). 4. Tropopsheric ozone: A continuing threat to global forests? (K.E. Percy, A.H. Legge, S.V. Krupa). Tropospheric Ozone. 5. Regional scale risk assessment of ozone and forests (G. Gerosa, A. Ballarin-Denti). 6. Limitations and perspectives about scaling ozone impacts in trees (T.E. Kolb, R. Matyssek). 7. Simulating the growth response of aspen to elevated ozone: A mechanistic approach from leaf-level photosynthesis to complex architecture (M.J. Martin, G.E. Host et al.). 8. Ozone affects the fitness of trembling aspen (D.F. Karnosky, K. Percy et al.). 9. Responses of Aleppo pine to O3 (R. Alonso, S. Elvira et al.). 10. Ozone affects Scots pine phenology and growth (S. Manninen, R. Sorjamaa et al.). 11. Ozone affects leaf surface-pest interactions (K.E. Percy, B. Mankovska et al.). 12. Ultrastructural response of a Mediterranean shrub species to O3 (F. Bussotti, E. Gravano et al.). 13. Ozone injury symptoms on vegetation in an alpine valley, North Italy (F. Bussotti, C. Mazzali et al.). Acidic Deposition. 14. Forest growth and critical air pollutant loads in Scandinavia (C. Nellemann, M.G. Thomsen et al.). 15. Norway spruce mortality and critical air pollutant loads (M.G. Thomsen, C. Nellemann). 16. Beech foliar chemical composition: A bioindicator of air pollution stress (G. Amores, J.M. Santamaria). 17. Atmospheric contamination of a wilderness park near a smelter in northern Michigan (W. Beer, E. Jepsen, J. Roth). 18. Mycorrhizal community structure of Scots pine trees exposed to acidic deposition (M. Rudawska, B. Kieliszewska-Rokicka et al.). Interaction of Air Pollutants and Climate Change. 19. Responses of forests in the northern U.S. to air pollution and climate change (R.A. Mickler, S.G. McNulty et al.). 20. An intensive monitoring study of air pollution stress in a beech forest in Spain (J.M. Santamaria, G. Amores et al.). 21. Effects of elevated carbon dioxide and acidic rain on the growth of Holm oak (E. Paoletti, F. Manes). 22. Effects of elevated CO2 and O3 on aspen clones of varying O3 sensitivity: Can CO2 ameliorate the harmful effects of O3? (B. Wustman, E. Oksanen et al.). 23. Growth responses of aspen clones to elevated carbon dioxide and ozone (J.G. Isebrands, E.P. McDonald et al.). Conclusions and Research Needs. 24. State of science and gaps in our knowledge in relation to air pollution (M. Ferretti, J. Bucher et al.). 25. Air pollution and global change impacts on forest ecosystems: Monitoring and research needs (D.F. Karnosky, K.E. Percy et al.). Author Index. Subject Index.

Initial response on nutritional status of a young Pinus radiata D.Don plantation to wood-ash application

The aim of the present study was to evaluate the effects of the application of wood-bark ash as a amendment and fertilizer of a young plantation of Pinus radiata grown on an acid soil. Two different doses of ash (5.000 and 10.000 kg ha-1) and one dose of 8:24:16 NPK fertilizer (200 g in hole) were applied at establishment. The response of the soil solid fraction and foliar chemical composition was studied throughout 28 months. Fertilization of the soil with wood-bark ash produced an increase in soil pH, at the same time increasing the availability of Ca, Mg, P and K. Related to this increase, the needle levels of Ca and, in a lower extent, Mg were also higher. Possible diagnosis of vector analysis of foliar nutrient contents and concentrations showed that these two elements limited the species growth.

Atmospheric CO2 enrichment alters leaf detritus: impacts on foraging decisions of crayfish (Orconectes virilis)

AbstractMany tree species demonstrate altered foliar chemical composition when grown under elevated CO2 conditions, decreasing the nutritional quality of leaves for herbivores and detritivores. Leaf litter comprises a substantial portion of the organic input into some headwater stream ecosystems, so changes in the chemistry of leaf detritus may affect the food-selection behavior of organisms, such as crayfish, that feed on it. Detritus from trembling aspen (Populus tremuloides) was produced under either the current CO2 concentration of 360 ppm (ambient, AMB) or twice the current concentration, 720 ppm (elevated, ELEV). A Y-maze was used to determine crayfish preference for AMB or ELEV detritus. Experimental conditions consisted of: 1) fresh detritus, 2) detritus that had been leached in water for 24 h, and 3) leachate from detritus (dissolved organic matter, DOM) made into a slow-releasing gelatin block. Pairwise combinations of stimuli (AMB, ELEV, and a no-stimulus control, CON) were compared within each...

Response of quaking aspen genotypes to enriched CO2: foliar chemistry and tussock moth performance

Abstract Genetic variation in the phytochemical responses of plants to CO2 enrichment is likely to alter trophic dynamics, and to shift intraspecific selection pressures on plant populations. We evaluated the independent and interactive effects of atmospheric CO2 and quaking aspen (Populus tremuloides Michx.) genotype on chemical composition of foliage and performance of the whitemarked tussock moth (Orgyia leucostigma J. E. Sm.). This research was conducted at the Aspen FACE (Free Air CO2 Enrichment) site in northern Wisconsin, U.S.A. Leaf samples were collected periodically from each of three genetically variable aspen genotypes growing under ambient and elevated CO2, and analysed for levels of primary and secondary metabolites. Tussock moth larvae were reared in situ on experimental trees, and development times and pupal masses were recorded. Foliar chemical composition varied among aspen genotypes and in response to CO2 enrichment. However, chemical responses of trees to elevated CO2 were generally consistent across genotypes. Larval development times varied among host genotypes and increased slightly for insects on high‐CO2 plants. Enriched CO2 tended to reduce insect pupal masses, particularly for females on one of the three aspen genotypes. CO2 × genotype interactions observed for plant chemistry and insect performance in this study with a small number of genotypes are probably too few, and too weak, to shift selection pressures in aspen populations. These results differ, however, from earlier work in which more substantial CO2 × genotype interactions were observed for plant chemistry.

Consequences of elevated carbon dioxide and ozone for foliar chemical composition and dynamics in trembling aspen ( Populus tremuloides) and paper birch ( Betula papyrifera)

Atmospheric chemical composition affects foliar chemical composition, which in turn influences the dynamics of both herbivory and decomposition in ecosystems. We assessed the independent and interactive effects of CO 2 and O 3 fumigation on foliar chemistry of quaking aspen ( Populus tremuloides) and paper birch ( Betula papyrifera) at a Free-Air CO 2 Enrichment (FACE) facility in northern Wisconsin. Leaf samples were collected at five time periods during a single growing season, and analyzed for nitrogen, starch and condensed tannin concentrations, nitrogen resorption efficiencies (NREs), and C:N ratios. Enriched CO 2 reduced foliar nitrogen concentrations in aspen and birch; O 3 only marginally reduced nitrogen concentrations. NREs were unaffected by pollution treatment in aspen, declined with O 3 exposure in birch, and this decline was ameliorated by enriched CO 2. C:N ratios of abscised leaves increased in response to enriched CO 2 in both tree species. O 3 did not significantly alter C:N ratios in aspen, although values tended to be higher in +CO 2+O 3 leaves. For birch, O 3 decreased C:N ratios under ambient CO 2 and increased C:N ratios under elevated CO 2. Thus, under the combined pollutants, the C:N ratios of both aspen and birch leaves were elevated above the averaged responses to the individual and independent trace gas treatments. Starch concentrations were largely unresponsive to CO 2 and O 3 treatments in aspen, but increased in response to elevated CO 2 in birch. Levels of condensed tannins were negligibly affected by CO 2 and O 3 treatments in aspen, but increased in response to enriched CO 2 in birch. Results from this work suggest that changes in foliar chemical composition elicited by enriched CO 2 are likely to impact herbivory and decomposition, whereas the effects of O 3 are likely to be minor, except in cases where they influence plant response to CO 2.

Atmospheric carbon dioxide, irrigation, and fertilization effects on phenolic and nitrogen concentrations in loblolly pine (Pinus taeda) needles.

Concentrations of total soluble phenolics, catechin, proanthocyanidins (PA), lignin and nitrogen (N) were measured in loblolly pine (Pinus taeda L.) needles exposed to either ambient CO(2) concentration ([CO(2)]), ambient plus 175 or ambient plus 350 micromol CO(2) mol(-1) in branch chambers for 2 years. The CO(2) treatments were superimposed on a 2 x 2 factorial combination of irrigation and fertilization treatments. In addition, we compared the effects of branch chambers and open-top chambers on needle chemistry. Proanthocyanidin and N concentrations were measured in needles from branch chambers and from trees in open-top chambers exposed concurrently for two years to either ambient [CO(2)] or ambient plus 200 micromol CO(2) mol(-1) in combination with a fertilization treatment. In the branch chambers, concentrations of total soluble phenolics in needles generally increased with needle age. Concentrations of total soluble phenolics, catechin and PA in needle extracts increased about 11% in response to the elevated [CO(2)] treatments. There were no significant treatment effects on foliar lignin concentrations. Nitrogen concentrations were about 10% lower in needles from the elevated [CO(2)] treatments than in needles from the ambient [CO(2)] treatments. Soluble phenolic and PA concentrations were higher in the control and irrigated soil treatments in about half of the comparisons; otherwise, differences were not statistically significant. Needle N concentrations increased 23% in response to fertilization. Treatment effects on PA and N concentrations were similar between branch and open-top chambers, although in this part of the study N concentrations were not significantly affected by the CO(2) treatments in either the branch or open-top chambers. We conclude that elevated [CO(2)] and low N availability affected foliar chemical composition, which could in turn affect plant-pathogen interactions, decomposition rates and mineral nutrient cycling.

Multivariate interpretation of the foliar chemical composition of Norway spruce (Picea abies)

Twenty-four chemical elements were analysed by INAA, ICP-AES and CN in needles of Norway spruce (Picea abies (L.) Karst.). Branches were sampled from 54 trees on eight sites in Switzerland and South Germany. From each tree, twigs were sorted into the most recent four or five age classes and their needles analysed separately. All measured concentrations could be considered as log-normally distributed and statistical analyses were, therefore, performed on logarithms. Variance components were estimated by maximum likelihood and compared between elements. Non-essential elements varied more than essential nutrients (Mn was an exception). The sites and the age of the needles were the most important sources of variance. The interaction between site and age, the individual tree, the sampled branch and the residual variance were usually much smaller sources of variance. The effects of the most significant factors – site and age – were further described by principal components and cluster analyses. Mineral elements either increased or decreased with the age of the needles according to their mobility in the phloem. Two different components were identified in the effect of the sites: a geochemical component linked to soil pH and a climate component linked to altitude, temperature and precipitation. Multivariate statistics are discussed as a tool for the interpretation of complex interaction patterns between element concentrations in plants.

Effects of clone and fertilization on the seed and foliar chemical composition of Scots pine (Pinus sylvestris) grafts

Effects of clone and fertilization on the seed and foliar nutrient concentrations of Scots pine grafts were investigated in a seed orchard in southern Finland. The seed and foliar samples for chemical analyses were collected during winters 1985–86 and 1988–89 from 39 grafts per clone fertilized in spring 1986. There were 6 clones and 13 treatments for each clone with three replications. The treatments consisted of N, P, K in various combinations, micronutrients, wood ash and grass control. Macro- (N, P, K, Ca, Mg) and micronutrients (Cu, Zn, B) were analysed. There were statistically significant differences between the clones in seed nutrient concentrations. The variation of the K, Mg, Ca, Zn and Cu concentrations between the two study years was considerably larger in the seeds than in the needles. The concentrations of these elements in the seeds were low in the year of an abundant seed crop in spite of fertilization. This had, however, no negative effects on germination of seeds. The proportions of crude fat and crude protein were high in both years (34% and 35% in 1985 ; 33% and 38% in 1988). Fertilization had only minor or no effect at all on the seed chemical composition in the orchard with a satisfactory nutrient status of the soil. Also on the foliar nutrient concentrations the effect of the clone was stronger than that of fertilization. Grafts with large needles produced heavy seeds, which had more storage proteins than the lighter seeds.

Wood Volume, Foliar Chemical Composition, and Soil Nitrogen Turn Over of Metrosideros polymorpha (Myrtaceae) Stands on a Slope of Mount Haleakala, Hawaii1

ABSTRACTAn earlier study suggested that soils on the windward slope of Mount Haleakala are excessively waterlogged at low altitudes but become better drained upslope. We analyzed altitudinal changes in soil N turn over, vegetation mass, and foliar chemical composition of the dominant canopy species, Metrosideros polymorpha (Myrtaceae), on this slope. The basal areas and DBH2× height (an index for volume) of woody species ≥2 m in height increased with altitude (as opposed to a general trend elsewhere), peaked at 1800 m elev., and abruptly declined above this altitude. Foliar N and P concentrations of Metrosideros showed a similar altitudinal trend with DBH2× height values. Foliar Fe and Al concentrations steadily increased downslope, but were low again at 450 m, the lowest altitude, contrary to expectation based on waterlogging. Toxic forms of Fe and Al may retard root penetration in waterlogged soils and thus the uptake of these elements. The net N mineralization rate for topsoils incubated in situ was 78.6 μg/g/20d at 1800 m elev., while small amounts of N were immobilized at 450, 1200 and 2200 m elev. The net N mineralization rates of the topsoils, which were air‐dried to their permanent wilting points and incubated at 26°C, were greater than those of the wet samples at 26°C, only for the lowest altitude. Conversely, the net N mineralization rates of the topsoils which were kept wet and incubated at the higher temperature of 26°C were greater (P < 0.1) than those of the in situ wet samples only for 1800 m elev. The rates were the same for 450 and 2200 m elev. where the soils were waterlogged and very dry, respectively; thus, N turn over was more strongly limited by moisture than by temperature in these cases. Nutrient availability improved with altitude up to 1800 m elev. in association with the moisture gradient, and appeared to be responsible for the observed pattern in vegetation mass.