bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seasonal and geographical variation of terpenes, resin acids and total phenolics in nursery grown seedlings of Scots pine (Pinus sylvestrisL.)
Authors: NERG A. , KAINULAINEN P. , VUORINEN M. , HANSO M. , HOLOPAINEN J. K. , KURKELA T. 
Published: April 2006

summaryVariations of terpene, resin acid and total phenolic concentrations in young seedlings of Scots pine (Pinus sylvestrisL.) from nine different seed origins growing in three locations of different latitudes, in Finland and Estonia, were investigated in autumn 1991 and spring 1992. Seasonal variation was remarkable in monoterpene, resin acid and total phenolic concentrations. In spring there was more 3‐carene, α‐pinent. β‐pinene + sabinene and total monoterpenes in pine shoots, and less myrcene and tricyclene compared to autumn. Concentrations of some individual resin acids, levopimaric and dehydroubietic acids, were higher in autumn. The total phenolic concentration was higher in spring. In the most northern location, the concentrations of total monoterpenes and total phenolics were lowest. The total resin acid concentration was highest in the middle location, and individual resin acids, palustric and neoabtetic acids, were more common in the most northern location. Seed origin had no significant effects either to the resin acid or total phenolic concentrations. There were almost equal concentrations of total phenolics and resin acids in northern and southern origins. Instead some individual monoterpenes. limonene, tricyclene, camphene, β‐pinene + sabinene and bornylacetate, were more common in northern seed origins. The results suggest that the origin of the seed material is not so important in affecting the concentrations of secondary compounds as are the environmental factors.
Leaf anatomy, specific mass and water content in congeneric annual and perennial grass species
Authors: GARNIER E. , LAURENT G. 
Published: April 2006

summaryPrevious experiments have shown that leaf specific mass (LSM: the ratio of leaf dry mass lo area) was lower and leaf water content (LWC) was higher in annuals than in perennials, differences that are more generally found between fast‐and slow‐growing species. Leaf transverse sections of seven annual‐perennial pairs of grass species grown in the laboratory were analyzed to elucidate the anatomical bases of these differences.Leaf thickness was similar in annuals and perennials, but leaf density was significantly higher in perennials. The proportion of the leaf volume occupied by mesophyll was higher in annuals, at the expense of the three other tissues (i.e. epidermis, sclerenchyma and vascular tissues). The cross‐sectional area of mesophyll cells was higher in annuals than in perennials, but epidermal cell size was similar for both life‐forms.The ranges of LSM (23.1–49.5 g m −2) and LWC (0.70–0.86 g g−1) displayed by the 14 species were large enough to examine the general relationships between these two parameters and various anatomical characters. LSM was significantly correlated with leaf density, but not with leaf thickness. The anatomical character that best explained interspecific differences in LSM was the volume of cell walls per unit leaf area (approximated by the sum: sclerenchyma + vascular tissues (including its living component) + cell wall components of mesophyll and epidermis). LWC was found to depend on leaf density, and interspecific differences in this parameter were best explained by the proportion of mesophyll protoplast (i.e. proportion of mesophyll minus proportion of mesophyll occupied by cell walls) in the transverse sections.The physiological and ecological implications of these findings are discussed in terms of a trade‐off between leaf productivity and persistence.
The Late‐Quaternary vegetational history of Loch a'Bhogaidh, Rinns of Islay S.S.S.I., Scotland
Authors: EDWARDS KEVIN J. , BERRIDGE JAMES M. A. 
Published: April 2006

summaryHolocene and partial Lateglacial age percentage and concentration pollen diagrams are presented of two profiles from the Inner Hebridean site of Loch a'Bhogaidh, Islay. The Lateglacial deposits may extend back to Lateglacial Interstadial times and a relative lack of Juniperus communis pollen is noted. The early Holocene deposits contain abundant Betula and Corylus avellana‐type pollen, followed by substantial amounts of pollen from other arboreal taxa, namely Pinus Sylvestris, I Ulmus, Quercus, Alnus glutinosa and Salix. There is pollen, charcoal and sedimentary evidence for possible Mesolithic age environmental impacts, and a hunter‐gatherer presence on Islay may date from the 10th millennium BP. Major woodland clearance dates from middle Bronze Age runes onwards (c. 3610 BP) and involved a mixed farming regime. The later Holocene records show that soil deterioration was occurring as heath and acid grassland taxa become prominent. These events may have resulted from land use pressures or climate change.
The Late‐glacial and Holocene vegetation of the Lang Lochs Mire area, Gulberwick, Shetland: a pollen and macrofossil investigation
Authors: HULME P. D. , SHIRRIFFS J. 
Published: April 2006

summaryA radiocarbon dated pollen and macrofossil record from Lang Lochs Mire, Shetland, is presented. Late‐glacial minerogenic and early Holocene gyttja sediments underlie mid and late Holocene peal. These indicate that the area was free from ice sometime before 13000 BP and there is evidence for a typical Devensian Late‐glacial climatic sequence as recorded elsewhere in Scotland.Until c. 10 500 BP an open vegetation with abundant masses amongst dwarf shrubs and herbs characterized the surrounding area. At c. 10500 BP gyttja deposition started, aquatic plants became abundant in the loch and Betula woodland developed around the loch. From r. 9700 BP to C. 7700 BP Corylus was also important. During this rime Alnus, Quercus and Ulmus pollen values rose but remained compatible with a long distance source for the pollen.At c. 7700 BP gyttja deposition ceased at the sample site and a poor fen developed. Around this, heathland and blanket peat vegetation started to develop from c. 7000 BP. By c. 6000 BP the area was largely treeless and after c. 5000 BP blanket peat spread and eventually dominated all but the steepest slopes.Pollen profile changes after c. 4500 BP can be attributed to either the spread of blanket peat or the effects of Neolithic peoples. The changes coincide with the arrival of Neolithic people elsewhere in Shetland. The first clear indication of Neolithic activity is dated to c. 3000 BP and coincides with increased activity in agriculturally more favourable areas of Shetland.Records of phytogeographically significant species are discussed and the value of combined macrofossil and pollen investigations is illustrated. The combined approach has helped to distinguish site and regional components of the pollen rain, the vegetational development of both the site and the surrounding area and has given a more accurate record of the occurrence of a number of taxa than could be achieved by pollen analysis alone.
Diffusion of CO2and other gases inside leaves
Authors: PARKHURST DAVID F. 
Published: April 2006

SUMMARYDiffusion of CO2in the intercellular airspaces of the leaf mesophyll is one of the many processes that can limit photosynthetic carbon assimilation there. This limitation has been largely neglected in recent years, but both theoretical and empirical evidence is presented showing that it can be substantial, reducing CO2assimilation rates by 25% or more in some leaves. Intercellular diffusion is fundamentally a three‐dimensional process, because CO2enters the leaf through discrete stomata, and not through a uniformly porous epidermis. Modelling it in one dimension can cause major underestimation of its limiting effects. Resistance and conductance models often fail to account well for the limitation, in part because they are usually one‐dimensional representations, but also because they treat continuously interacting processes as if they were sequential. A three‐dimensional diffusion model is used to estimate the intercellular limitation in leaves of different structural types. Intercellular gaseous diffusion probably limits CO2assimilation by at most a few percent in many of the agricultural plants commonly studied by laboratory physiologists, as they usually have thin, amphistaomatous leaves. However, it may cause substantial limitations in the thicker, often hypostomatous leaves of the wild plants that occupy large areas of the earth. Several physiological implications of intercellular diffusion are discussed. I close by reiterating published suggestions that the gas‐exchange parameter commonly termed pishould be renamed pes(es for evaporating surfaces) to avoid the confusing implication that p1, is‘the’intercellular CO2pressure.ContentsSummary449I.Introduction450II.Theory of intercellular gaseous diffusion451III.Evidence regarding intercellular gaseous diffusion hmitations461IV.Discussion of assumptions made in §11.1470V.Physiological implications of intercellular gaseous diffusion471VI.Conclusions475Acknowledgements476Appendix, Example showing breakdown of resistance analogy for diffusion with distributed uptake476References477
Annual carbon balance and nitrogen‐use efficiency in tropical C3 and CAM epiphytes
Authors: ZOTZ GERHARD , WINTER KLAUS 
Published: April 2006

SUMMARYOver the course of 12 months, diel (24 h) measurements of gas exchange were performed on leaves of three epiphytic species growing in the crown of a kapok tree on Barro Colorado Island, Panama: a drought‐deciduous orchid with the C2, pathway (Catasetum viridiflavum Hook.), an evergreen C2 fern (Polypodium crassifolium L.), and an evergreen epiphyte with an intermediate C3‐C3‐CAM pathway of photosynthesis (Clusia uvitana Pitt.), The gas exchange characteristics of all three species; were strongly affected during the four‐month dry season. Compared with the rainy season, mean daily carbon gain of Clusia uvitana was reduced by almost 40° paralleled bY a strong decrease in daytime CO2 uptake and an increase in CO2 uptake at night. The orchid, growing new leaves in the second half of the dry season, showed markedly decreased stomatal conductances and greatly reduced carbon gain. In the fern, daily carbon balance became negative during the dry season and chronic photoinhibition was indicated by reduced FV/FM ratios and a decreased photon‐use efficiency of photosynthetic O2 evolution. Annual carbon gain was similar far the three species (about 10002 CO2 m‐2 yr‐1) as was long‐term nitrogen‐use efficiency (annual carbon gain/mean leaf nitrogen content, about 1·1 g CO2 mg N‐1 yr‐1). In the C3CAM epiphyte, the long‐term water use efficiency of net CO2 uptake was more than twice as high as in the two C3 epiphytes.
Effects of exposure to ozone and water stress on the following season's growth of beech (Fagus sylvatica L.)
Authors: PEARSON M. , MANSFIELD T. A. 
Published: April 2006

SUMMARYBud break and growth of beech trees were measured during the growing season of 1992. The trees had previously been exposed, through the growing season of 1991, to one of four treatments: (1) episodic ozone for 128 d, total dose = 46‐3 ppm h; (2) air purified by filtration through Purified and charcoal; (3) ozone together with a period of water shortage: (4) filtered air with a period of water shortage.Despite uniform growth conditions during 1992. the previous water stress treatment caused bud break to begin slightly earlier, but the rates of shoot growth and the length of the first flush branches were reduced (40%). In well‐watered plants ozone caused a reduced Tate of shoot growth during the first week after bud break. The total amount of growth during 1992 was shown to be reduced (36%) by the previous water stress treatment, In the case of the well‐watered trees, exposure to ozone in the previous year reduced the amount of new growth by 17%, which was the result of reduced internal expansion. When ozone was combined with water stress, there was no further reduction in the amount of new growth, but there was a fall in the number of internodes relative to water‐stressed plants grown in filtered air.Ozone and water stress applied singly reduced growth. A combination of the two stresses, however, caused no additional reduction in growth, but reduced the number of internodes. The possible implications of the aftereffects of these stresses are discussed in relation to reduced productivity and canopy structure.
Simultaneous eutrophication and acidification of a forest ecosystem in North‐East France
Authors: THIMONIER A. , DUPOUEY J. L. , BOST F. , BECKER M. 
Published: April 2006

SUMMARYSurveys of ground layer vegetation are a reliable tool for monitoring spatial and temporal variations of the forest environment. In 1991, 47 vegetation plots first sampled in 1972 in a forest of the Lorraine Plain, North‐East France, were resampled. This beech–oak forest had both acidic and calcareous soils depending on the thickness of alluvial deposits above the calcareous bedrock. The mean number of species per sample increased from 32 to 39 during this period and the frequency of nitrophilic species increased throughout the forest. On acidic soils, acidophilic species increased in frequency, while on calcareous soils there were no systematic changes. Multivariate statistical analysis clearly distinguished two gradients in this set of vegetation samples: acidity and nitrogen availability of soils. Along the first gradient, a shift of the plots towards a more acidic state occurred during the past 19 years on acidic soils only. Along the second one. a strong eutrophication happened on both acidic and calcareous soils, indicating an enrichment in nitrogen of forest ecosystems. Possible causes of these changes are discussed, namely sylviculture changes, aging of the stands and pollution. Atmospheric nitrogen inputs seem to be the most probable cause of eutrophication.
The control of cell expansion in roots
Authors: PRITCHARD JEREMY 
Published: April 2006

SUMMARYThe expansion of roots is considered at the level of the single cell. The water relations of cell expansion are discussed. Water entry, solute import and cell wall properties are considered as possible regulatory points. It is argued that root cell expansion can be understood in terms of cell turgor pressure and the physical properties of the cell wall, provided solute supply is not limiting. Various measurements of cell wall properties in roots are presented and the assumptions underlying their measurements are presented. It is concluded that cell wall properties must be measured over short time periods to prevent alterations in wall properties during the experiment. The radial location of the load‐bearing layers is discussed and it is concluded that, unlike aerial tissue, growth is limited by the properties of the inner layer of the root cortex. Evidence is presented to show that cell wall properties can change both during development and following turgor perturbation. In general, however, turgor itself is tightly regulated, particularly towards the root tip. A number of environmental situations are presented in which root growth is altered. The mechanism of the alteration is discussed at the single cell level. These 'stresses’include osmotic stress, low temperature and soil compaction. In many cases the alteration of root growth is consistent with changes in the ceil wall properties of the growing ceils. Severe stress, resulting in near cessation of root cell extension, can result in a change (usually an increase) in turgor pressure. The change in turgor pressure of the cells in the growing zone is smaller than that which would be expected from a continuation of an unstressed solute import rate. This exemplifies both the change in cell wall properties and the tight turgor homeostasis of root tips.The biochemical processes which underlie the modulation of cell wall properties are presented as they are currently understood in roots. Measurements of the chemical composition of the wall have not revealed any useful differences which can explain the developmental or stress‐induced changes in cell wall properties. Recent work on cell wall enzymes and proteins may provide information about control of cross‐linkages within the wall.In the last section the relative importance of apoplastic and symplastic solute transport to the expanding cells is considered. At present the consensus appears to favour the symplastic route, but the apoplastic pathway may also operate, possibly as a scavenging mechanism for leaked ions. The regulation of turgor pressure by linking solute import with wall loosening is discussed.

Contents

Summary
3

I.
Introduction
4

II.
Factors controlling cell expansion
4

III.
Wall extensibility and yield threshold in roots
6

IV.
Environmental effects on root cell expansion
10

V.
Modification of cell wall biochemistry
15

VI.
Linkage of growth with solute import
18

VII.
Future prospects
21

VIII.
Acknowledgements
22

IX.
References
22
Influence of the host on three sub‐Arctic annual facultative root hemiparasites
Authors: SEEL W. E. , PRESS M. C. 
Published: April 2006

SUMMARYLight saturated rates of photosynthesis (Asat), water use‐efficiency (WUE) and photosynthetic nitrogen use‐efficiency (PNUE) were measured for three sub‐Arctic annual root hemiparasites (Rhinanthus minorL.,Euphrasia frigidaL. andMelampyrum sylvaticum L.)growing in the Torneträsk region of Swedish Lapland. Photosynthesis and resource use‐efficiency of the hemiparasites were dependent on (i) attachment to a host and (ii) the nature of the host to which attachment was made. The highest rates ofAsatwere recorded in those hemiparasites attached to legumes and the lowest rates were recorded in those which were not attached to a host. Intermediate rates of Asatwere recorded in hemiparasites attached to grasses. Asatand leaf conductance were more closely related in attached than in unattached hemiparasites, WUE was greatest in those hemiparasites attached to legumes, but was not a simple function of nitrogen supply. PNUE was greater in attached than in unattached plants, but was inversely related to the total‐nitrogen concentration of the leaves. In an earlier paper we demonstrated that the growth of these hemiparasites is highly host dependent. Here we demonstrate that the carbon, nitrogen and water relations of these plants are also highly host dependent.
Heavy metal accumulation and tolerance in British populations of the metallophyte Thlaspi caerulescens J. & C. Presl (Brassicaceae)
Authors: BAKER A. J. M. , REEVES R. D. , HAJAR A. S. M. 
Published: April 2006

SUMMARYHeavy metai uptake, accumulation and tolerance were investigated in five British populations of the metallophyte Thlaspi caerulescens from metalliferous sites from the north and south Pennines orefields. Analysis of field samples showed mean shoot Zn, Pb and Cd concentrations of up to 21000, 660 and 164/zMug g‐1 respectively. A solution culture experiment designed to investigate both tolerance and metal accumulation is reported. Indices of tolerance of five populations to 12 metals (Ag, Al, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Zn) showed few population differences but unexpectedly high tolerance to metals not present at elevated concentrations in the parent soils. This was paralleled by exceptionally high uptakes of all metals studied. Zn, Cd, Co, Mn and Ni were readily transported to the shoot whereas Al, Cr Cu, Fe and Pb were predominantly immobilized in the roots. The data suggest common mechanisms of absorption and transport of several metals in this species.
Causal mechanisms by which sulphate, nitrate and acidity influence frost hardiness in red spruce: review and hypothesis
Authors: SHEPPARD LUCY J. 
Published: April 2006

SUMMARYThis paper summarizes results from four experiments in which red spruce seedlings(Picea rubensSarg.) were exposed to simulated acid mist containing SO42‐, NH4‐, NO3‐and H+ions. Seedlings were grown in compost, with or without fertilizer, in charcoal filtered air in open‐top chambers near Edinburgh, Scotland. Plants were sprayed from bud burst between May and November with mist containing different concentrations and combinations of the four major ions to provide a range of doses, which were applied at different frequencies.Reductions in frost hardiness expressed in terms of the temperature which killed 50% of shoots (LT50) were significantly correlated with the dose of S received by the seedlings. Differences in foliar S concentrations between the controls and treated plants were correlated with S dose. Absolute S concentrations were, however, of limited use for predictive purposes.Seedlings appear to be more sensitive than older trees to S toxicity because the former have the greatest proportion of newly expanding needles which optimize conditions for foliar uptake. Seedlings are also least well equipped to export SO42‐ions since they have a smaller resource of older foliage to supplement their assimilate pool.In conditions which promote uncontrolled SO42‐ion uptake byfoliage, i.e. high external SO42‐concentrations and incompletely formed cuticles, the potential exists for the internal build up of SO42‐ions. It is proposed that in the absence of sufficient assimilate and K the presence of these high concentrations of SO42‐ions in the apoplast or cytosol can lead to protein denaturation and loss of membrane integrity. Reductions in frost hardiness appear to result through direct attack by SO42ions on membrane proteins which impairs their function. Indirect effects on hardiness occur through both an increased consumption of sugars reducing the‘pool’available for cryoprotection and a reduction in photosynthetic function, the ability to produce sugars. The presence of NO3‐N mitigates the toxic effects of SO42because SO42ions are consumed in assimilation processes which both utilize and are facilitated by the presence of large amounts of fertilizer N. High concentrations of SO42and H+ are found to be particularly toxic because of the synergistic effects these ions exert on their mutual uptake with devastating consequences for the control of cellular pH.Trees growing at high altitude sites are likely to be particularly sensitive to SO42‐toxicity because (1) their carbon balance is low, (2) cuticle development is poor and (3) levels of soil available Ca2tend to be low relative to Al3+so that membranes may already be weakened as a result of insufficient Ca2+ions for protein bridging.
The significance of nodal rooting in Trifolium repens L.: 32P distribution and local growth responses
Authors: KEMBALL W. D. , MARSHALL C. 
Published: April 2006

SUMMARYThe distribution of 32P from single nodal roots, and the consequences of nodal rooting on local growth characteristics were investigated in order to evaluate the importance of nodal rooting in Trifolium repens. The movement of radiophosphate was mostly acropetal, and the principal sinks were the closest components to the supplied root. The branch stolon originating from the same node as the root was the mast significant sink, and its importance as sink increased the older and larger it became. Nodal rooting on the main stolon resulted in a localized increase in secondary branching on the primary branch originating from the same node. The results are discussed in terms of physiological integration in T. repens and other clonal plants.