A novel technique for reducing soil fertility in ecological restoration projects

Surface soil eutrophication hinders ecological restoration projects by favouring communities of low biodiversity. This study assesses the effectiveness of a novel technique known as topsoil inversion that may promote recovery from eutrophication. Topsoil inversion is undertaken by a deep plough, which buries 30 cm of topsoil under approximately 40 cm of subsoil. The main study site is within new community woodland on former agricultural land. It comprises deep ploughed and conventionally ploughed plots, to compare two planting types: wildflowers only, and wildflowers with trees. This presentation will discuss some preliminary findings of the effect of topsoil inversion on soil properties and plant tissue nutrient content. Surface soil fertility is lowered following inversion treatment, and this appears to affect plant nutrient sequestration. These results suggest that topsoil inversion has the potential to facilitate ecological restoration on eutrophic soil. This technique may have benefits for restoration projects taking place in a variety of habitats affected by air pollution, including former agricultural land and lowland heaths

Sphagnum farming from species selection to the production of growing media : a review

Sphagnum farming - the production of Sphagnum biomass on rewetted bogs - helps towards achieving global climate goals by halting greenhouse gas emissions from drained peat and by replacing peat with a renewable biomass alternative. Large-scale implementation of Sphagnum farming requires a wide range of know-how, from initial species selection up to the final production and use of Sphagnum biomass based growing media in horticulture. This article provides an overview of relevant knowledge accumulated over the last 15 years and identifies open questions.Peer reviewe

Genetic analysis of the naked trait in panicles of hexaploid oat

The aim of this study was to estimate the number of genes that control the naked (hull-less) trait and the mode of expression of this characteristic in panicles of hexaploid white oat. Parents and the segregating population (in the F2 and F3 generations) were evaluated in regard to the presence and distribution of naked grains in panicles of individual oat plants. For each plant, a drawing of the main panicle was developed. From the drawings obtained in the progenies of the F2 population, six distinct phenotypic classes were produced. The expected phenotypic proportion of 3:9:4 (naked:segregating:hulled) was that which best fit by the Chi-square test. In the F3 generation, the results showed agreement with the hypothesis observed in the F2 generation. The naked trait in oat is passed on by two genes and the greatest expression of this trait occurs in the upper third of the panicles. Expression of this trait in oats is not complete, even in homozygous genotypes

Nitrogen Deposition Reduces Plant Diversity and Alters Ecosystem Functioning: Field-Scale Evidence from a Nationwide Survey of UK Heathlands

Findings from nitrogen (N) manipulation studies have provided strong evidence of the detrimental impacts of elevated N deposition on the structure and functioning of heathland ecosystems. Few studies, however, have sought to establish whether experimentally observed responses are also apparent under natural, field conditions. This paper presents the findings of a nationwide field-scale evaluation of British heathlands, across broad geographical, climatic and pollution gradients. Fifty two heathlands were selected across an N deposition gradient of 5.9 to 32.4 kg ha−1 yr−1. The diversity and abundance of higher and lower plants and a suite of biogeochemical measures were evaluated in relation to climate and N deposition indices. Plant species richness declined with increasing temperature and N deposition, and the abundance of nitrophilous species increased with increasing N. Relationships were broadly similar between upland and lowland sites, with the biggest reductions in species number associated with increasing N inputs at the low end of the deposition range. Both oxidised and reduced forms of N were associated with species declines, although reduced N appears to be a stronger driver of species loss at the functional group level. Plant and soil biochemical indices were related to temperature, rainfall and N deposition. Litter C:N ratios and enzyme (phenol-oxidase and phosphomonoesterase) activities had the strongest relationships with site N inputs and appear to represent reliable field indicators of N deposition. This study provides strong, field-scale evidence of links between N deposition - in both oxidised and reduced forms - and widespread changes in the composition, diversity and functioning of British heathlands. The similarity of relationships between upland and lowland environments, across broad spatial and climatic gradients, highlights the ubiquity of relationships with N, and suggests that N deposition is contributing to biodiversity loss and changes in ecosystem functioning across European heathlands

The effect of salinity upon photosynthesis in rice (Oryza sativa L.): gas exchange by individual leaves in relation to their salt content

The effect of salinity upon net photosynthesis and transpiration by individual leaves of rice has been investigated by gas exchange measurements in seedlings at the five to six leaf stage. Salinity did not, initially, reduce net photosynthesis in the whole plant but only in the older leaves in which sodium accumulated. Analysis of the course of events in leaf four following salinization of the medium showed that net photosynthesis was inversely correlated with the sodium concentration in the leaf tissue. There was no evidence of a threshold effect; net photosynthesis declined linearly with increasing leaf sodium concentration and was reduced by 50% at only 05 mmol sodium per gram dry weight. The relationship between transpiration rate and leaf sodium concentration closely paralleled that for photosynthesis; there was no effect of leaf sodium concentration on the carbon dioxide concentration in the intercellular spaces, showing that sodium accumulation in the leaf affected stomatal aperture and carbon dioxide fixation simultaneously. Photosynthesis was reduced by half at a sodium concentration in the leaf which did not reduce the concentration of chlorophyll. The nature of the effect of salinity upon leaf gas exchange is discussed

The effect of exposure to NO 2 and SO 2 on frost hardiness in Calluna 6ulgaris

Abstract Heather (Calluna 6ulgaris) was grown in pots in a natural heathland soil and exposed in outdoor fumigation chambers ('solardomes') to 40 nl l − 1 of both nitrogen dioxide (NO 2 ) and sulphur dioxide (SO 2 ) simultaneously. Plants exposed to NO 2 and SO 2 for 8 months over a growing season (February -November) showed increases in the growth of shoots ( +37%) and the whole plant ( + 15%) and a raised ratio of root to shoot dry matter in comparison with control (charcoal-filtered air) plants. Fumigation raised the average foliar concentrations of nitrogen ( +34%) and sulphur ( +173%). The improvements in growth due to pollutant exposure were countered by reductions in tolerance to experimental acute frost. Cellular damage of heather shoots was assessed using measurements of electrolyte leakage from cut shoots following controlled over-night frosts. The rates of leakage were consistently increased in those plants that had been exposed to NO 2 and SO 2 for 5 months or more in comparison with non-fumigated controls. In some cases a greater leakage rate was recorded in fumigated plants than in controls even in the absence of freezing temperatures. The pollutants caused a similar reduction in frost tolerance whether exposure was given during the hardening period (August-January) or the de-hardening stage (November -April). These results support the hypothesis that low concentrations of air pollutants can reduce the tolerance of plants to freezing stress

The Use of 14C-Ethane Diol as a Quantitative Tracer for the Transpirational Volume Flow of Water and an Investigation of the Effects of Salinity upon Transpiration, Net Sodium Accumulation and Endogenous ABA in Individual Leaves of Oryza sativa L.

Oryza sativa L. (rice) seedlings growing in saline conditions exhibit pronounced gradients in leaf sodium concentration which is always higher in the older leaves than the younger ones. Individual leaf transpiration rates have been investigated to discover whether movement of sodium in the transpiration stream is able to explain these profiles from leaf to leaf. The use of 14C labelled ethane diol to estimate transpiration was evaluated by direct comparison with values obtained by gas exchange measurements. Ethane diol uptake was linearly related to the transpirational volume flow and accurately predicted leaf to leaf gradients in transpiration rate in saline and non-saline conditions. 14C-ethane diol and 22NaCl were used to compare the fluxes of water and sodium into different leaves. The youngest leaf showed the highest transpiration rate but the lowest Na accumulation in saline conditions; conversely, the older leaves showed the lower transpiration rates but the greater accumulation of Na. The apparent concentration of Na in the xylem stream was 44 times lower into the younger leaf 4 than into the older leaf 1. Exposure to NaCl (50 mol m−3) for 24 h elicited an increase in endogenous ABA in the oldest leaf only, but no significant changes occurred in the younger leaves