Developmental disorders in buds and needles of mature Norway spruce, Picea abies (L.) Karst., in relation to needle boron concentrations

Dieback of the terminal shoot and consequently bushy growth induced by boron deficiency have been reported widely throughout the world in several tree species. Recently, similar growth damage was documented in half of the young spruce stands in eastern Finland. To clarify the role of B deficiency, the light microscopic structure of emerging buds and of developing and previous-year needles of mature Norway spruce (Picea abies L. Karst.) from damaged (D stand), partly damaged (PD stand) and healthy (H stand) stands were analysed. The samples, on which needle nutrient concentrations were also determined, were taken seven times between early spring (April) and early winter (November). Cell death characterized by precipitation of the cell content, possibly due to the release of tannins after membrane rupture, was seen in the apex of emerging buds, and this led to fatal damage in about half of the buds in the trees from the D stand, where the needle B concentration was well below the deficiency level of 4–5 mg kg⁻¹. Furthermore, an increase in living cells that accumulated tannins in the vacuoles, which is a common stress and/or defense reaction, was found in the primordial shoots of buds and in the differentiating needles in the PD and D stands. The increase in the areas of the central cylinder and of the xylem found in the needles indicate structural plasticity during needle differentiation to drought. The time frame for bud emergence from late May up to mid-September means that an adequate B supply is necessary throughout the summer in order to avoid fatal bud damage and thus bushy growth of the trees.     

Diurnal Changes in Microscopic Structures of Mesophyll Cells of Norway Spruce, Picea abies(L.) Karst., and the Effects of Ozone and Drought

Microscopy has been used to diagnose the effects of air pollutantson conifers. As sampling may be slow, it is important to knowwhether the structure of needles changes during the day. Usinglight- and electron microscopy, diurnal changes in the structureof mesophyll cells of current year needles from 6-year-old Norwayspruce saplings were studied on one day in early autumn, 1995.Saplings had been grown in open-top chambers and exposed toozone and drought stress during the 1992–1995 growingseasons. In all treatments, the proportion of cells with smallcytoplasmic vacuoles and with large cytoplasmic lipid depositsdecreased during the day. Mitochondria increased in size fromearly morning to midday, after which time they shrank progressively.Ozone affected the shape of mitochondria: the proportion oftube-shaped mitochondria decreased from early morning in controlsaplings, whereas it increased in ozone-treated saplings. Starchaccumulated during the day, but to a lesser extent in drought-stressedsaplings than well-watered controls. Microbodies were smallerin drought-stressed saplings than in controls early in the morning,but their size then increased compared to that of the controls.Cellular and sub-cellular disorganization, probably due to sub-optimalfixation procedures, were detected in all treatments, especiallyin the morning, but these decreased later, particularly in well-wateredsaplings. Results show that microscopy is a sensitive and validtool for studying stress responses in plants. However, the timeof sample collection must be considered and documented to avoidmisleading conclusions due to actual diurnal changes and fixationproblems. Copyright 2001 Annals of Botany Company Diurnal changes, drought, light microscopy, mesophyll cells, needles, Norway spruce, Picea abies, ozone, transmission electron microscopy     

Does the removal of snowpack and the consequent changes in soil frost affect the physiology of Norway spruce needles?

Climate change may cause a decrease in snow cover in northern latitudes. This, on the other hand, may result in more severe soil frost even in areas where it is not common at present, and may lead to increased stress on the tree canopy. We studied the effects of snow removal and consequent changes in soil frost and water content on the physiology of Norway spruce (Picea abies [L.] Karst.) needles and implications on root biomass. The study was conducted at a 47-year-old Norway spruce stand in eastern Finland during the two winters of 2005/06 and 2006/07. The treatments in three replicates were: (i) natural snow accumulation and melting (CTRL), (ii) artificial snow removal during the winter (OPEN), and (iii) the same as OPEN, but the ground was insulated in early spring to delay soil thawing (FROST). In spite of the deeper soil frost in the OPEN than in the CTRL treatment, soil warming in spring occurred at the same time, whereas soil warming in the FROST was delayed by 2 and 1.5 months in 2006 and 2007, respectively. The soil water content was affected by snow manipulations, being at a lower level in the OPEN and FROST than CTRL in spring and early summer. The physiological measurements of the needles (e.g. starch, carbon and nitrogen content and apoplastic electrical resistance) showed differences between soil frost treatments. The differences were mostly seen between the CTRL and FROST, but also in the case of the starch content in early spring 2007 between the CTRL and OPEN. The needle responses in the FROST were more evident after the colder winter of 2006. The physiological changes seemed to be related to the soil temperature and water content in the early growing season rather than to the wintertime soil temperature. No difference was found in the fine root (diameter < 2 mm) biomass between the treatments assessed in 2007. In the future, conditions similar to the OPEN treatment may be more common than at present in areas experiencing a thick snow cover. The present experiment took place over the course of two years. It is possible that whenever thin snow cover occurs yearly, the reduced starch content during the early spring may be reflected in the tree growth itself as a result of reduced energy reserves.     

Importance of soil calcium for composition of understory vegetation in boreal forests of Finnish Lapland

To focus conservation efforts into forest areas with high biodiversity, more information is needed about soil-vegetation dependencies in Finnish Lapland. We studied understory vegetation and soil variables along a transect across a felsic?Cmafic lithological sequence in central Finnish Lapland. At 119 northern boreal forest sites, coverages of understory vegetation, several mineral soil chemical elements, soil electrical conductivity, pH, and dielectric permittivity, as a measure of soil volumetric water content, were measured. We found that soil Ca concentration and Ca:Al ratio were the main variables determining vegetation composition and diversity. Ca-rich soils were characterised by high electrical conductivity, pH, and Mg concentration, and by low concentration of Al, S, Zn, and low C:N ratio. Soil Ca concentration is a diagnostic measure of plant diversity as concentration higher than 100 mg kg^?1 resulted in a considerable increase in plant diversity. Sites with Ca concentration this high were rare, and probably important in maintaining high biodiversity. The median soil Ca:Al ratio was only 0.02, suggesting, according to general theory, a considerable risk for aluminium stress. We found Geranium sylvaticum and Rubus saxatilis to be good indicators for Ca-rich regimes and high plant diversity.     

Cell structural changes in the needles of Norway spruce exposed to long-term ozone and drought

Effects of ozone and/or drought on Norway spruce needles werestudied using light microscopy and electron microscopy. Saplingswere exposed to ozone in open-top chambers during 1992–1995and also to drought in the late summers of 1993–1995.Samples from current and previous year needles were collectedfive times during 1995. Ozone increased the numbers of peroxisomesand mitochondria, which suggests that defence mechanisms againstoxidative stress were active. The results from peroxisomes suggestthat the oxidative stress was more pronounced in the upper sideof the needles, and those from mitochondria that defence wasmore active in the younger needle generation. Possibly due tothe good nitrogen status and the active defence, no ozone-specificchloroplast alterations were seen. At the end of the season,older needles from ozone treatments had smaller central vacuolescompared with other needles. Cytoplasmic vacuoles around thenucleus were increased by ozone in the beginning of the experiment,and did not increase towards the end of the season as in thecontrols. These results from vacuoles may indicate that ozoneaffected the osmotic properties of the cells. Decreased numberand underdevelopment of sclerenchyma cells and proliferationof tonoplast were related to nutrient imbalance, which was enhancedby drought. Larger vascular cylinders and more effective starchaccumulation before and after the drought periods compensatedfor the reduced water status. Numbers of peroxisomes and mitochondriawere increased in the drought-exposed needles before the onsetof drought treatments of the study year, i.e. these changeswere memory effects. Interactions between ozone and droughtwere few.     

Predicting spring frost sensitivity by bud development and temperature sum in Norway spruce seedlings

Nurseries would benefit greatly if frost hardiness (FH) of seedlings could be predicted by some environmental variable or by bud development in spring. We investigated the FH of 1-year-old Norway spruce (Picea abies (L.) Karst.) seedlings of local origin. The seedlings were stored frozen until incubated in the growth chamber at six different temperature sums (TSs) (0, 55, 88, 142, 185 and 240 d.d., >5°C) from mid-February to mid-March. FH of the buds, stems and previous year needles was assessed on three occasions. When the TS was 88 d.d. or less, buds exhibited only microscopic signs of development, even when seedlings tolerated temperatures below −10°C. As TS increased, primordial needles and primordial stems of buds grew while FH weakened, especially in previous year needles. When the TS was at least 142 d.d., all plant parts were frost hardy to approximately −6°C. Monitoring TS and bud development can help predict FH of Norway spruce seedlings in spring. However, more studies with seedlings of different ages and from multiple locations are necessary to appreciate the generality of our results.     

Effects of rosiglitazone on gene expression in subcutaneous adipose tissue in highly active antiretroviral therapy-associated lipodystrophy

Highly active antiretroviral therapy (HAART) has improved the prognosis of human immunodeficiency virus (HIV)-infected patients but is associated with severe adverse events, such as lipodystrophy and insulin resistance. Rosiglitazone did not increase subcutaneous fat in patients with HAART-associated lipodystrophy (HAL) in a randomized, double-blind, placebo-controlled trial, although it attenuated insulin resistance and decreased liver fat content. The aim of this study was to examine effects of rosiglitazone on gene expression in subcutaneous adipose tissue in 30 patients with HAL. The mRNA concentrations in subcutaneous adipose tissue were measured using real-time PCR. Twenty-four-week treatment with rosiglitazone (8 mg/day) compared with placebo significantly increased the expression of adiponectin, peroxisome proliferator-activated receptor-gamma (PPARgamma), and PPARgamma coactivator 1 and decreased IL-6 expression. Expression of other genes involved in lipogenesis, fatty acid metabolism, or glucose transport, such as acyl-CoA synthase, adipocyte lipid-binding protein, CD45, fatty acid transport protein-1 and -4, GLUT1, GLUT4, keratinocyte lipid-binding protein, lipoprotein lipase, PPARdelta, and sterol regulatory element-binding protein-1c, remained unchanged. Rosiglitazone also significantly increased serum adiponectin concentration. The change in serum adiponectin concentration was inversely correlated with the change in fasting serum insulin concentration and liver fat content. In conclusion, rosiglitazone induced significant changes in gene expression in subcutaneous adipose tissue and ameliorated insulin resistance in patients with HAL. Increased expression of adiponectin might have mediated most of the favorable insulin-sensitizing effects of rosiglitazone in these patients.     

Measuring and explaining noncompliance in federally managed fisheries

Abstract

This article focuses on measuring and explaining noncompliance in federally managed U.S. fisheries. Novel measurement techniques are used to characterize the extent and patterns of noncompliance in the northeast groundfish fishery. According to the authors’ estimates, noncompliance increased substantially in 1986 and remained high through 1988 in the groundfish fishery. On Georges Bank during 1987, a quarter to a half of all groundfish vessels were identified as frequent violators, committing closed area violations on about one‐third of their trips and using illegal mesh on nearly all trips. Illegal earnings by a typical frequent violator operating in the groundfish fishery on Georges Bank amounted to $225,000 per year in 1987.

A theory of compliance in fisheries is developed and applied to explain the trends and patterns of noncompliance in the northeast groundfish fishery. Biological and economic forces are shown to be dominant causes of the recent deterioration in compliance. Other contributing factors include weak sanctions and insufficient enforcement resources. The article concludes with a prognosis for the fishery and recommendations for improving compliance.     

Different response of two reindeer forage plants to enhanced UV-B radiation: modification of the phenolic composition

The long-term effects of enhanced UV-B radiation on the content and composition of leaf phenolics in Epilobium angustifolium L. and Eriophorum russeolum Fries ex Hartman were studied in northern Finland (68°N) using two UV-B enhancement experiments, both simulating UV-B_CIE radiation and corresponding to a 20% loss of ozone layer. High proportions of hydrolyzable tannins (69%) and condensed tannins (66%) characterized both Epilobium and Eriophorum leaves, respectively. No UV treatment effect was detected in the content or composition of Epilobium leaf soluble phenolics, whereas significant UV effects were detected in Eriophorum leaves in a developmental-specific manner. At the end of the growing season, the proportion of total soluble phenolics was higher in leaves exposed to enhanced UV-A and UV-B radiation than in the control leaves, but the phenolic composition was not significantly modified. This study introduces a new example on plants’ phenolic response to UV radiation being species-specific and detectable only at certain developmental stages. Possible consequences of increased phenolic content in forage plants for selection and digestibility by reindeer are, however, not yet known.