Foliage Concentrations Research Articles

Assessment of the potential role of metals in sugar maple (Acer saccharum Marsh) decline in Ontario, Canada

Spatial and temporal differences in the crown condition of sugar maple (Acer saccharum Marsh) in Ontario remain largely unexplained. In this study, the potential role of metals in sugar maple dieback was explored by measuring metal concentrations in foliage and forest floor (LFH) at 35 forest stands in south-central Ontario that exhibit varying levels of decline and span a climatic, soil acidity and acid deposition gradient. Foliar and forest floor metal concentrations varied among sites by between two and ten-fold, with acidic sites exhibiting the highest concentrations of many metals in the forest floor and foliage. Sites with moderate decline symptoms (decline index (DI) > 10, averaged between 1986 and 2004) had significantly greater Cd, Zn, Cu, Pb and Mn concentrations and lower Ca concentrations in the forest floor compared with healthy sites (DI < 10). Foliar concentrations of Cd, Sr and Mn were also significantly greater and Ca was significantly lower in sites with moderate decline symptoms compared with healthy sites. However the highest metal concentrations in foliage and the forest floor found in this study are lower than critical values reported in the literature. The notable exception is Mn where values at acidic sites may be high enough to negatively impact sugar maple.

Soil heavy-metal distribution and transference to soybeans surrounding an electroplating factory

Heavy-metal pollution of soils and crops is an often overlooked issue that is becoming increasingly serious. A study of soybean production on soils surrounding an electroplating factory in the Yangtze River Delta of China was conducted to identify heavy-metal mobility and spatial distribution in soils, their transfer to plant tissues, and subsequent changes in plant enzymatic activities. The results indicated systematic Ni and Zn contamination of soils and soybean crops in this region. Zinc and Cu were distributed along a gradient and their concentrations in soil and soybean foliage were closely related, suggesting that their similar spatial distribution in soil and soybean foliage was affected by factory contamination. The combinations of soil heavy-metal pollutants influenced the total amounts of heavy-metal pollutants in soybean foliage. In soybean foliage, the activity of peroxidase was significantly correlated with Ni, Cu, Zn, and their ionic impulsion (an index of plant-soil pollution). Peroxidase activity may be an appropriate biomarker for heavy-metal accumulation in soybean foliage.

Long-term trends of phosphorus nutrition and topsoil phosphorus stocks in unfertilized and fertilized Scots pine ( Pinus sylvestris) stands at two sites in Southern Germany

For two Scots pine ( Pinus sylvestris) ecosystems in S Germany with different atmospheric N deposition ( Pfaffenwinkel, intermediate N deposition; Pustert, large N deposition), the supply with phosphorus (P) has been monitored for unfertilized and fertilized plots over more than four decades by foliar analysis (1964–2007). Additionally, topsoil concentrations and stocks of total P and plant-available P (citric-acid-extractable phosphate) were quantified in 10-year intervals (1982/1984, 1994, 2004). At both sites, fertilization experiments, including the variants control, NPKMgCa + lime, PKMgCa + lime + introduction of lupine, corresponding to an addition of 75 and 90 kg ha −1 P in Pustert and Pfaffenwinkel, respectively had been established in 1964. Our study revealed different trends of the P nutritional status for the pines at the two sites during the recent four decades: At Pustert, elevated atmospheric N deposition together with small topsoil P pools resulted in significant deterioration of Scots pine P nutrition and in an increasingly unbalanced N/P nutrition. At Pfaffenwinkel a trend of improved P nutrition from 1964 to 1991 was replaced by an opposite trend in the most recent 15 years. For our study sites, which are characterized by acidic soils with thick O layers, the forest floor stock of citric-acid-extractable phosphate showed a strong and significant correlation with the P concentration in current-year pine foliage, and thus was an appropriate variable to predict the P nutritional status of the stands. Total P stocks as well as the concentrations of total P in the forest floor or in the mineral topsoil were poorly correlated with pine foliar P concentrations and thus inappropriate predictors of P nutrition. P fertilization in the 1960s sustainably improved the P nutritional status of the stands. At Pfaffenwinkel, foliar P concentrations and topsoil stocks of citric-acid-extractable phosphate were increased at the fertilized plots relative to the control plots even 40 years after fertilization; at Pustert, foliar P concentrations were increased for about 20 years.

Early ontogenetic trajectories vary among defence chemicals in seedlings of a fast-growing eucalypt

Ontogenetic changes in leaf chemistry can affect plant–herbivore interactions profoundly. Various theoretical models predict different ontogenetic trajectories of defence chemicals. Empirical tests do not consistently support one model. In Eucalyptus nitens, a fast-growing tree, we assessed early developmental changes to seedlings, in foliage concentrations of nitrogen and the full suite of known secondary (defence) chemicals. This included the terpene, α-pinene, whose impact on marsupial herbivory is unknown. To test for the influence of abiotic conditions on the ontogenetic trajectories we overlaid a nutrient treatment. Ontogenetic trajectories varied among compounds. Sideroxylonals and cineole were barely detected in very young seedlings, but increased substantially over the first 200 days. Total phenolic concentration increased fourfold over this time. In contrast, α-pinene concentration peaked within the first 60 days and again between 150 and 200 days. Nutrients altered the degree but not the direction of change of most chemicals. A shorter trial run at a different season showed qualitatively similar patterns, although α-pinene concentration started very high. We investigated the effect of detected levels of α-pinene and cineole on food intake by two mammalian herbivores, common brushtail possums (Trichosurus vulpecula) and red-bellied pademelons (Thylogale billardierii). Under no-choice conditions neither terpene reduced intake; but with a choice, possums preferred α-pinene to cineole. The ontogenetic trajectories of most compounds were therefore consistent with models that predict an increase as plants develop. Published data from later developmental stages in E. nitens also confirm this pattern. α-Pinene, however, was the only secondary compound found at significant levels in very young seedlings; but it did not constrain feeding by marsupial herbivores. Models must allow for different roles of defensive secondary chemicals, presumably associated with different selective pressures as plants age, which result in different ontogenetic trajectories.

Calcium fertilization increases the concentration of calcium in sapwood and calcium oxalate in foliage of red spruce

Calcium cycling plays a key role in the health and productivity of red spruce forests in the northeastern US. A portion of the flowpath of calcium within forests includes translocation as Ca 2+ in sapwood and accumulation as crystals of calcium oxalate in foliage. Concentrations of Ca in these tree tissues have been used as markers of environmental change due to acidic deposition or forest management practices. We compared the effects of Ca fertilization treatment on Ca concentration in wood and Ca and oxalate (Ox) concentration in foliage at two locations with different initial concentrations of Ca in the soil. We found greater amounts of Ca in wood from the high-Ca location than from the low-Ca location. Ca concentration was greater in wood formed in the 1970s than for wood formed in the 1980s, the outermost decadal band in these samples. The Ca-treatment was detected as an increased concentration of Ca in the 1970s and 1980s decadal bands. We also found that variation in Ca and Ox in foliage was essentially stoichiometric. The appearance and response to chemical tests of crystals in foliage were consistent with identification as calcium oxalate. The increased Ca in wood after Ca-treatment of the soil supports the use of dendrochemistry of base cations to investigate environmental change. However, differences in Ca concentration between the two outermost decadal bands of wood illustrate that internal processes of translocation and storage also affect Ca concentration. Calcium oxalate production in foliage diverts carbon from ordinary biosynthesis and energy-yielding processes. This sequestration, shedding, and decomposition of foliage may represent a significant and under-recognized contribution to carbon and Ca cycling.

Total Phenolic Content of Asian Elm Leaves and Host Plant Suitability for Gypsy Moth

Abstract The total phenolic content of foliage from 11 elm species and 2 cultivars was measured, and the relationship to gypsy moth developmental studies was determined. The 13 elms, Ulmus wilsoniana (Schneid.), U. japonica (Rehd.), U. glaucesens (Franch), ‘Accolade’, ‘Triumph’, U. davidiana (Planch), U. parvifolia (Jacq.), U. szechuanica (Fang), U. macrocarpa (Hance), U. chenmoui (Cheng), U. lamellosa (C. Wang et S.L. Chang, ex L.K. Fu), U. castaneifolia (Hemsl.), and U. gaussenii (Cheng), were grown at the Morton Arboretum, Lisle, IL and analyzed at the Pesticide Toxicology Laboratory, Iowa State University, Ames, IA. Significant differences were found in the phenolic content of the 13 elms surveyed. No significant differences were identified between gypsy moth larval longevity, pupal fresh weight, or percentage adult emergence with respect to total leaf phenolic content.

A COMPARATIVE STUDY FOR IMPACT OF LOW PHOSPHORUS FERTILIZATION IN DIFFERENT COMBINATIONS WITH SULPHUR, GYPSUM AND PHOSPHOREIN ON TOMATO GROWTH, MINERAL STATUS AND PRODUCTIVITY.

Two field experiments were conducted at Kalabshow district, Dakahlia Governorate during two successive summer seasons of 2007 and 2008 to study the effect of phosphorus fertilizers,i.e., super phosphate and rock phosphate in different combination with gypsum, sulphur and phosphorein on growth ,mineral composition and productivity of tomato cv. Super marmand . The experiment included fourteen treatments arranged in randomized complete block design. The treatments contained two sources of phosphorus (P) fertilizers [super phosphate (SP) and rock phosphate (RP) at 100% from recommended dose (RD),i.e,75KgP2O5] and different combination of SP or RP at low rate (65%),i.e,52.5 KgP2O5 of RD) with gypsum (G),sulphur (S)and phosphorein(Phn). The main results were as follows: 1- Addition of super phosphate(SP) at 65 % of the recommended phosphorus rate(RD) with gypsum(G) and phosphorein(Phn) as soil amendment had a significant effect on number of leaves per plant, plant height , roots& shoots and total dry weights per plant as well as relative dry weight (%)during the two seasons. 2-Application of rock phosphate (RP) at 65 % of the recommended phosphorus rate RD) resulted in significant decrease of foliage concentration of N and P as well as the N, P ,K total uptake from N,P,K in both seasons. 3- The highest significant N and P concentration and N, P and K uptake were resulted from application of super phosphate (SP) at 65 %from RD in the presence of gypsum (G) and phosphorein (Phn) at both seasons. 4- Addition of the recommended phosphorus rate as super phosphate(SP) or applying (SP) at 65% from RD with gypsum and phosphorein showed the most superior effect regarding average fruit weight, number of fruits and fruit yield of tomato plant as well as total yield per feddan. 5- Application of super phosphate (SP) at 65 %with gypsum (G) and phosphorein (Phn) resulted in 6.45 % increment in the total yield comparing to the control treatment (average of the two seasons) . 6- Applying super phosphate (SP) at 65% from RD with gypsum (G) and phosphorein (Phn) showed the superior significant values for most fruit quality, i.e., T.S.S %, Vit C and total carbohydrates content of tomato fruits. In general, this study demonstrated that it is possible to produce highest growth, yield and quality of tomato plants by applying super phosphate at 65 % of the recommended phosphorus rate with 2.5 ton/feddan of gypsum and 1 kg/feddan of phosphorein. Moreover, the phosphatic fertilization can be reduced by 35 % of the recommended rate beside reduction of chemical pollution.

Improved nutritional status of Cupressus lusitanica when grown adjacent to Pinus radiata

We examined how a mixture of Pinus radiata D. Don and Cupressus lusitanica Mill. influences foliage element concentrations at 20 sites, covering a fertility gradient. Foliage element concentrations of plants at plot boundaries, where the two species grew adjacent to each other, were compared with those of plants at plot centres, where they were surrounded by plants of the same species. For C. lusitanica, plot position significantly affected nitrogen (N), phosphorus (P), and sulphur (S) with concentrations of these elements at the plot boundary exceeding concentrations at the plot centre by 10%–14%. For P. radiata, plants at the plot boundary had a significantly greater P concentration and lower N/P ratio than plants at the centre, but differences between positions were less than that for C. lusitanica (&lt;7%). For C. lusitanica, the difference between foliage concentrations of N and P at the plot boundary and centre significantly declined as the mean plot concentrations of these elements increased. It is likely that C. lusitanica at the boundary benefited from the greater availability of N, P, and S in the root rhizosphere, where they were mobilized from soil organic matter by the ectomycorrhizae of P. radiata. We also suggest that P. radiata at the plot boundary may have benefited from mobilization of P by the endomycorrhizae of C. lusitanica.

Simplified method for determining cadmium concentrations in rice foliage and soil by using a biosensor kit with immunochromatography

AbstractBACKGROUND: The behavior of cadmium in ecosystems needs to be monitored because of the human toxicity of this heavy metal. The need recently arose for a simple and quick on‐site test for trace levels of Cd in food and environmental samples. In response, an immunochromatographic assay kit for detecting Cd was manufactured by Kansai Electric Power Co. of Japan. This kit uses the antigen–antibody complex reaction between the Cd–EDTA complex and an anti‐Cd–EDTA antibody and shows the results in terms of the degree of color developed on a test paper. We previously reported the successful use of this kit to determine Cd concentrations in brown rice. Here, we applied the kit to the determination of Cd concentrations in rice foliage and soil.RESULTS: Cadmium in rice foliage was not extracted successfully by the method used for brown rice. However, it was successfully extracted by 0.1 mol L−1 HCl solution at a rice foliage:HCl ratio of 1:20, and coexisting metals were removed sufficiently by the column treatment. The Cd concentrations determined by immunochromatographic assay were well correlated with the values obtained by acid decomposition and inductively coupled plasma mass spectrometry. The 0.1 mol L−1 HCl‐extractable Cd concentration in soil was also determined successfully with the kit.CONCLUSION: Approximate Cd concentrations in rice plants and 0.1 mol L−1 HCl‐extractable Cd concentrations in soil can be monitored easily and quickly by this method at locations where facilities for acid digestion and precision analysis are not available. Copyright © 2009 Society of Chemical Industry

Indirect effects of invasive predators on litter decomposition and nutrient resorption on seabird‐dominated islands

Despite recent interest in the ecosystem impacts of invasive aboveground organisms, most work in this area has focused on effects of invasive plants, and the effects of invasive herbivores and predators remain poorly understood. We studied 18 forested, offshore islands in northern New Zealand. Nine of these host high densities of burrowing seabirds that serve as ecosystem drivers by transporting nutrients from the ocean to land. The other nine have been invaded over the past 50-150 years by rat species introduced from Europe which serve as predators of seabird eggs and chicks and severely reduce their densities. We collected fully expanded leaves and fresh leaf litter from invaded and uninvaded islands for each of 12 perennial plant species that represent a wide spectrum of life forms from ground dwelling to emergent canopy species. We found that, across these species, invasion by rats significantly reduced nitrogen (N) but not phosphorus (P) concentrations of foliage and litter, promoted N but not P resorption from leaves before litter fall, and reduced the release of N but not P from decomposing litter. Rat invasion also negatively affected litter decomposability but had no overall effects on litter quality variables other than N. Our results provide evidence that rat invasion causes more conservative cycling of N but not P through foliage and litter and limitation of ecological processes by N but not P. We found few instances in which the effects of rat invasion on response variables varied significantly across plant species, meaning that invasion had similar effects for species that varied greatly in growth form and foliar and litter quality. Further, correlation analyses across the 12 species showed that foliar and litter quality traits were poor predictors of how invasion effects on resorption and decomposition variables varied among species. Our results show that the effects of invasive predators on native prey can have substantial indirect effects on variables relevant for ecosystem functioning. These types of effects are probably widespread, especially given the role of seabirds in improving soil fertility in many coastal ecosystems worldwide and the wide global distribution of predators of seabirds.

The role of permanent site factors in the assessment of soil treatment effects: A case study with a site preparation trial in jack pine plantations on glacial outwashes

In silvicultural trials, the confounding influence of permanent soil properties is assumed to be minimal. A covariance analysis using total elemental concentrations of parent material (geochemistry) and soil particle size distribution (texture) was used to understand the role that these variables could play in tree growth and foliar nutrient status, and in the growth response to site preparation of 16- to18-yr-old jack pine plantations growing on seemingly homogeneous glacial outwash deposits. Three treatments were tested in a replicated design: direct plantation, and site preparation with TTS or with Bräcke. The combination of particle size distribution and soil geochemistry explained the site quality index (SQI) in control plots (R2 = 0.94) better than soil texture alone. In all plots, SQI was strongly related to K and Mg concentrations in foliage and in humus and, to a lesser degree, to foliar N concentrations. A covariance analysis using soil texture and geochemical composition indicated that while site preparation had an effect on tree growth, the sites that responded the most to site preparation were the ones with the lowest growth potential as determined by soil texture and geochemistry. Key words: Silviculture, site preparation, site quality index, growth, permanent soil factors, texture, geochemistry, nutrition

Imperata cylindrica, an alien invasive grass, maintains control over nitrogen availability in an establishing pine forest

In a field experiment in Florida, USA, 15N-labeled Ammonium Sulfate was used to compare how Pinus taeda seedlings take up and use N in the presence of I. cylindrica and native vegetation using three treatments: 1) vegetation free 2) native competition, and 3) I. cylindrica competition. Imperata cylindrica competition led to smaller pine seedlings with significantly less N content in the pine foliage and roots than those in the native treatment. Competition from I. cylindrica for N contributed to the pine seedlings taking up a greater percentage of the applied fertilizer than the seedlings competing with native vegetation; however, because of their reduced growth they were less efficient in utilizing the fertilizer N. The belowground biomass of I. cylindrica on average was seven times higher than the native species. Despite its lower N concentration in foliage and roots, it retained significantly more N per hectare compared to the native vegetation. While the native species retained more N aboveground, I. cylindrica held significantly more belowground, thus invasion by this grass would lead to a shift of N pools from above to belowground. The fact that we were able to account for 81.5% of the applied fertilizer in the I. cylindrica treatment compared to 62.2% in the native treatment suggests that I. cylindrica tightly retains most of the available N on site making it a particularly good invader.

Effects of experimental acidification and alkalinization on soil and growth and health of Acer saccharum Marsh.

AbstractExperimental application of eight acidifying, neutral, or alkalizer compounds (range: –16 to 16 kmol ha–1 of acid‐neutralizing capacity [ANC]) was realized in two northern hardwood stands having significantly different soil base saturation (BS) (a “poor” and a “rich” site) to assess responses of soil physico‐chemical properties, and nutrition, growth, and health of sugar maple (Acer saccharum Marsh.) trees in the short (3 y) and longer term (10 y). The treatments influenced the main indicators of acidity in the forest floor (soil exchangeable‐Ca saturation [SCa], BS, exchangeable‐acidity saturation [SH+Al], and the SCa/SH+Al ratio) at both sites, their values increasing (decreasing for SH+Al) along the ANC treatment gradient in both the short and longer term, except for pH. Base saturation of the upper 15 cm of the mineral B horizons of soils was influenced at the two sites 10 y after treatment application. Although ANC treatments affected nutrient concentrations of tree foliage in the short term, their effect was no longer detectable after 10 y at the two sites. Growth, however, was strongly related to ANC treatments after 10 y, but only at the poor site. From 1990 to 2000, the basal‐area growth rate of trees at the poor site was (mean ± SE) –0.62 ± 0.28 cm2 y–2 tree–1 for the most negative ANC treatment to +0.90 ± 0.20 cm2 y–2 tree–1 for the most positive ANC treatment. A climatic‐stress episode occurring in 1995/96 appeared to accentuate the growth decline of trees subjected to the most negative ANC treatment at the poor site. The experimental results support the hypothesis that atmospheric acid deposition load can cause forest soil base‐cation depletion, acidification, and predispose sugar maple to health and growth decline in the longer term in base‐cation‐poor soils, and that the phenomenon may be reversible by adding alkalizers.

Effects of Fertilization and Fungal and Insect Attack on Systemic Protein Defenses of Austrian Pine

Despite their economic and ecological importance, defense responses of conifers to pests are little understood. In a 3-year experiment, we monitored systemic fungal (Diplodia pinea)- and insect (Neodiprion sertifer)-induced defense protein activities and total soluble proteins in needles and phloem of Austrian pine (Pinus nigra) across a soil fertility gradient. In both years, total soluble protein content of foliage and phloem declined with increasing fertility across induction treatments, while defensive protein activities generally increased with increasing fertility. In 2005, total soluble protein content in branch phloem was increased by fungal inoculation of the stem. Peroxidase activity was suppressed in needles by insect defoliation in 2006, while polyphenol oxidase activity was systemically induced in branch phloem by insect attack in 2005. Trypsin inhibitor activities in phloem did not respond to any induction or fertility treatment. Nutritive quality of Austrian pine tissue declined with increasing fertility, while several protein-based defenses simultaneously increased.

Combined Effect of Intercropping and Turnip Root Fly (Delia floralis) Larval Feeding on the Glucosinolate Concentrations in Cabbage Roots and Foliage

The effects of plant competition and herbivory on glucosinolate concentrations in cabbage root and foliage were investigated in a cabbage-red clover intercropping system. Cabbage plants were grown under different competitive pressures and with varying degrees of attack by root-feeding Delia floralis larvae. Glucosinolate concentrations in cabbage were affected both by intercropping and by D. floralis density. Glucosinolate concentrations in foliage generally decreased as a response to intercropping, while the responses to insect root damage of individual glucosinolates were weaker. Root glucosinolates responded more strongly to both intercropping and egg density. Total root glucosinolate concentration decreased with clover density, but only at high egg densities. Increased egg density led to opposite reactions by the indole and aliphatic glucosinolates in roots. The responses of individual root glucosinolates to competition and root damage were complex and, on occasion, nonlinear. Reduced concentrations of several glucosinolates and the tendency towards a decrease in total concentration in cabbage foliage caused by intercropping and larval damage suggest that competing plants or plants with root herbivory do not allocate the same resources as unchallenged plants towards sustaining levels of leaf defensive compounds. This could also be true for root glucosinolate concentrations at high egg densities. In addition, the results suggest that changes occurring within a structural group of glucosinolates may be influenced by changes in a single compound, e.g., glucobrassicin (indol-3-ylmethyl) in foliage or sinigrin (2-propenyl) in roots.

Stem girdling manipulates leaf sugar concentrations and anthocyanin expression in sugar maple trees during autumn

To better understand the effects of sugar accumulation on red color development of foliage during autumn, we compared carbohydrate concentration, anthocyanin expression and xylem pressure potential of foliage on girdled versus non-girled (control) branches of 12 mature, open-grown sugar maple (Acer saccharum Marsh.) trees. Half of the study trees were known to exhibit mostly yellow foliar coloration and half historically displayed red coloration. Leaves from both girdled and control branches were harvested at peak color expression (i.e., little or no chlorophyll present). Disruption of phloem export by girdling increased foliar sucrose, glucose and fructose concentrations regardless of historical tree color patterns. Branch girdling also increased foliar anthocyanin expression from 50.4 to 66.7% in historically red trees and from 11.7 to 54.2% in historically yellow trees, the latter representing about a fivefold increase compared with control branches. Correlation analyses indicated a strong and consistent relationship between foliar red coloration and sugar concentrations, particularly glucose and fructose, in both girdled and control branches. Measures of xylem pressure potentials confirmed that girdling was a phloem-specific treatment and had no effect on water transport to distal leaves. Results indicate that stem girdling increased foliar sugar concentrations and enhanced anthocyanin expression during autumn in sugar maple foliage. Native environmental stresses (e.g., low autumn temperatures) that reduce phloem transport may promote similar physiological outcomes.

Dynamics of low-temperature acclimation in temperate and boreal conifer foliage in a mild winter climate

To provide baseline data for physiological studies of extreme low-temperature (LT) tolerance in boreal conifers, we profiled LT stress responses, liquid nitrogen (LN(2))-quench tolerance, and sugar concentrations in foliage of boreal-temperate species pairs in the genera Abies, Picea and Pinus, growing in an arboretum in a temperate oceanic climate from August 2006 through April 2007. The boreal species acclimated more rapidly and deeply than the temperate species, acquiring LN(2)-quench tolerance by late November, despite unusually warm conditions throughout the autumn and early winter. Maximum LT tolerance in the temperate species was in the -25 to -35 degrees C range, and was reached only after a period of freezing temperatures in late January and February. During LT acclimation in the temperate species, sigmoid temperature-relative electrolyte leakage (REL) curves shifted toward lower temperatures, whereas in boreal species there was both a temperature shift and a lowering of the maximum REL until it fell below a threshold associated with irreversible injury. These differences may reflect differences in mechanisms of LT acclimation and LT tolerance. The concentrations of total and individual sugars did not show a clear pattern that could differentiate the boreal and temperate groups. Raffinose and, in three of the six species, stachyose showed the closest association with LT tolerance. Sugar concentrations, principally sucrose, decreased during mild weather, perhaps because of respiratory losses or phloem export, and increased after periods of freezing temperatures. Low-temperature acclimation in boreal species appears to follow a rigid program that may affect their ability to avoid excessive respiratory losses in the event of continued climate warming in boreal regions.

Nutrient contents and efficiencies of beech and spruce saplings as influenced by competition and O3/CO2 regime

Saplings of Fagus sylvatica and Picea abies were grown under conditions of intra and interspecific competition in a 2-year phytotron study under combinations of ambient and elevated ozone (+O3 which is 2 × O3, but <150 nl l−1) as well as carbon dioxide concentrations (+CO2 which is amb. CO2 + 300 μl CO2 l−1) in a full factorial design. Saplings were analysed for various mineral nutrients in different plant organs as well as biomass production and crown development. The study was based on the assumption that nutritional parameters important for growth and competitiveness are affected by stress defence under limiting nutrient supply. The hypotheses tested were (1) that nutrient uptake-related parameters (a) as well as efficiencies in nutrient use for above-ground competition (b) of beech rather than spruce are impaired by the exposure to elevated O3 concentrations, (2) that the efficiency in nutrient uptake of spruce is enhanced by elevated CO2 concentrations in mixed culture, and (3) that the ability to occupy above-ground space at low nutrient cost is co-determinant for the competitive success in mixed culture. Clear nitrogen deficiencies were indicated for both species during the 2-year phytotron study, although foliar nitrogen-biomass relationships were not so close for spruce than for beech. O3 stress did not impair nutrient uptake-related parameters of beech; thus hypothesis (1a). was not supported. A negative effect of elevated O3 (under amb. CO2) on the N and P based efficiencies in above-ground space occupation (i.e. lower crown volume per unit of N or P invested in stems, limbs and foliage) of beech supported hypothesis (1b). It appeared that ozone stress triggered a nutrient demand for stress defence and tolerance at the expense of above-ground competition (trade-off). Crown volume of beech under O3 stress was stabilized in monoculture by increased nutrient uptake. In general, the +CO2-treatment was able to counteract the impacts of 2 × O3. Elevated CO2 caused lower N and S concentrations in current-year foliage of both tree species, slightly higher macronutrient amounts in the root biomass of spruce, but did not increase the efficiencies in nutrient uptake of spruce in mixed culture. Therefore hypothesis (2) was not supported. At the end of the experiment spruce turned out to be the stronger competitor in mixed culture as displayed by its higher total shoot biomass and crown volume. The amounts of macronutrients in the above-ground biomass of spruce individuals in mixed culture distinctly exceeded those of beech, which had been strongly reduced by interspecific competition. The superior competitiveness of spruce was related to higher N and P-based efficiencies in above-ground space occupation as suggested in hypothesis (3).

Mosses and foliage of forest tree species as biomonitors of nitrogen pollution

The foliage N concentrations were determined in 405 permanent monitoring plots (PMP) in four National Parks (NP) and 16 Landscape Protection Areas (NPA) and were compared with 3062 PMP in Slovakia. The foliage concentration of N ranged from 9.7 to 48.7 mg kg−1 in conifers (Picea abies Karst., Pinus silvestris L.), and from 7.8 to 51.4 mg kg−1 in broadleaved forests (Fagus sylvatica L., Quercus robur L.). A low level of N was determined in one LPA and a critical increase in four NPAs. The S/N ratio ranged from 0.08 to 0.176 in conifers, and from 0.078 to 0.253 in broadleaved tree species. The S/N ratio was dislocated on 90% of localities when compared with the range limit. Concentrations of N in the foliage of three forest tree species (1101 trees) from 24 sites of the Carpathian Mountains forests – in the Czech Republic (CZ), Poland (PL), Romania (RO), Slovakia (SK) and Ukraine (U) – were evaluated and compared taking the limit values into account. The foliage concentrations of N for Fagus sylvatica L. were all over the European threshold value of 20.8 mg kg−1 (i.e. 26.24±14.47(CZ); 28.2±18.15 (PL); 23.1±2.1 (RO); 23.9±3.6 (SK); 26.6±2.7 (U)). The concentrations in the foliage of Picea abies Karst and Abies alba Mill. were also over or around the European Union limits. The results for the atmospheric deposition of N in 6 Slovak sites using the moss biomonitoring technique are also presented in this study. Concentrations of N (in g. kg−1) in the three‐year‐old segments of mosses (Pleurozium schreberi, Hylocomium splendens and Dicranum sp.) ranged from 19.6 to 27.3 (2000); from 9 to 24.9 (2005). In comparison to the year 2000, we found increased N concentrations in 2005.

Nutrient status of managed and natural forest fragments of Fagus sylvatica in southern Europe

Beech forests located in the southwestern limit of Europe have been affected by severe deforestation and long-term fragmentation. Some of these forests have been subjected to partial cutting, whereas others have been maintained with little or no active management. It has previously been shown that past management has led to substantial changes in tree structure, diversity and plant species. These perturbations, through their influence on the litterfall and forest floor, may affect nutrient cycling and the nutritional status of such fragile ecosystems. Mineral nutrition was investigated in 53 forest fragments by analysis of data corresponding to nutrient concentrations in forest floor, mineral soils and foliage. In comparison with other beech forests in Central Europe subjected to higher levels of air pollution, the stands showed fewer incidences of nutrient deficiencies and lower foliar concentrations of S and heavy metals. Partial cuts carried out in recent decades have reduced the forest floor mass proportional to the intensity of the harvesting. The effect was probably due to the lower litter input and the increased decomposition of litter as a consequence of the environmental changes in forest gaps. The partially cut stands displayed higher foliar levels of K and Mg, which could be attributed to the greater release of these elements as a consequence of the increased decomposition of litter. However, past management has brought about lower foliar concentrations of P and N. Both effects were found to be proportional to basal area and the forest floor mass, which suggests that they are related to the intensity of harvesting. Although the causes are uncertain, this negative effect may be due to a reduction in forest floor thickness, which implies the loss of preferred rooting space for trees.