bluuebunny/crossref_metadata_2025_split huggingface dataset:
Potential of multi‐objective models for risk‐based mapping of the resilience characteristics of soils: demonstration at a national level
Authors: Debeljak M. , Kocev D. , Towers W. , Jones M. , Griffiths B. S. , Hallett P. D. 
Published: February 2009

AbstractPolicy makers rely on risk‐based maps to make informed decisions on soil protection. Producing the maps, however, can often be confounded by a lack of data or appropriate methods to extrapolate using pedotransfer functions. In this paper, we applied multi‐objective regression tree analysis to map the resistance and resilience characteristics of soils onto stress. The analysis used a machine learning technique of multiple regression tree induction that was applied to a data set on the resistance and resilience characteristics of a range of soils across Scotland. Data included both biological and physical perturbations. The response to biological stress was measured as changes in substrate mineralization over time following a transient (heat) or persistent (copper) stress. The response to physical stress was measured from the resistance and recovery of pore structure following either compaction or waterlogging. We first determined underlying relationships between soil properties and its resistance and resilience capacity. This showed that the explanatory power of such models with multiple dependent variables (multi‐objective models) for the simultaneous prediction of interdependent resilience and resistance variables was much better than a piecewise approach using multiple regression analysis. We then used GIS techniques coupled with an existing, extensive soil data set to up‐scale the results of the models with multiple dependent variables to a national level (Scotland). The resulting maps indicate areas with low, moderate and high resistance and resilience to a range of biological and physical perturbations applied to soil. More data would be required to validate the maps, but the modelling approach is shown to be extremely valuable for up‐scaling soil processes for national‐level mapping.
Succession during the re‐creation of a flood‐meadow 1985‐1999
Authors: McDonald Alison W. 
Published: February 2009

Abstract. The study site, Somerford Mead, is located on the river Thames floodplain and was a species‐rich flood‐meadow in the 1950s. In the 1960s and 1970s it was subjected to intensive grassland management with regular NPK additions and occasional herbicide treatment. In 1981 Somerford Mead was ploughed for the first time and converted to arable land. Seeds of an Alopecuruspratensis‐Sanguisorba officinalis flood‐meadow community (MG4; Rodwell 1992) were sown onto prepared soil in the autumn of 1986, and botanical records were made from 1985 to 1999. From 1989 to 1999, three replicates of three treatments: cow‐grazing, sheep‐grazing and no‐grazing were introduced after hay‐cutting. Analysis successfully separated the establishment phase from the experimental phase and showed a significant difference between the grazed and ungrazed treatments. Abiotic and biotic factors which might contribute to successional trends are discussed. A convoluted pattern for each treatment could be attributed in part to intrinsic‘cycles’of perennial hemicryptophytes behaving as short‐lived species and in part to the percentage frequency of many species which was reduced in 1990 and 1995/1996, years of drought. After the initial inoculation of MG4 seed and the disappearance of arable therophytes, recruitment of new species was very slow. Coefficients for Somerford Mead matched against MG4 (Rodwell 1992) produced an equilibrium within three years. It subsequently fluctuated over a 10‐yr period well below the level of Oxey Mead, the donor site.Land managers should ensure that their proposed site has the right soils and hydrology for MG4 grassland and that traditional management of hay‐cutting and aftermath grazing is practised. Only one cut a year in July could lead to a reduction in percentage frequency of most species except Arrhenatherum elatius.
Do life history traits predict responses to defoliation in co‐occurring prairie grasses?
Authors: Teague W.R. , Dowhower S.L. 
Published: February 2009

Abstract. This study examines whether competition between the unpalatable grass Hilaria mutica and three co‐occurring, palatable grasses in a Texan mixed prairie is altered by non‐selective or selective defoliation. In this four‐year study, plants were grown in monoculture or in combination with the unpalatable Hilaria in a replacement design.Under no defoliation, the unpalatable Hilaria had a lower growth potential than Bouteloua curtipendula and Nassella leucotricha that were of equal stature, and produced only as much as the shorter grass, Buchloe dactyloides. Bouteloua had the highest growth potential under no‐defoliation and was defoliation tolerant, except when defoliated at ground level. Nassella was more productive than the unpalatable Hilaria, since the ability to grow earlier in the year enabled it to compete successfully with Hilaria. These results indicate that with adequate deferment Bouteloua and Nassella should compete successfully with Hilaria and Buchloe should be able to maintain itself in the presence of Hilaria.Under non‐selective defoliation, Hilaria was able to compete successfully only with Buchloe. Hilaria was sensitive to defoliation, despite being rhizomatous, and competed less successfully with Buchloe after non‐selective defoliation than it did when not defoliated. This indicates that the management practice of burning and stocking heavily with livestock until Hilaria is avoided, resulting in non‐selective defoliation, will not cause Hilaria to be more competitive with the more palatable Bouteloua, Buchloe or Nassella.Hilaria was able to compete most successfully under selective defoliation when it was not defoliated. Under selective defoliation, by avoiding herbivory, Hilaria is able to compete strongly with at least Buchloe and Nassella. The reaction of Nassella and Buchloe to selective defoliation indicates that they may have been displaced by Hilaria in the past. In contrast, under the short‐term and non‐limiting growth conditions of this study, Bouteloua competed successfully with Hilaria even under selective defoliation. These results do not rule out the possibility that, through selective defoliation, Hilaria may have displaced other grasses including Bouteloua in the past.
Vegetation change in a man‐made salt marsh affected by a reduction in both grazing and drainage
Authors: Esselink Peter , Fresco Latzi F.M. , Dijkema Kees S. 
Published: February 2009

Abstract. In order to restore natural salt marsh in a 460‐ha nature reserve established in man‐made salt marsh in the Dollard estuary, The Netherlands, the artificial drainage system was neglected and cattle grazing reduced. Vegetation changes were traced through two vegetation surveys and monitoring of permanent plots over 15 yr after the management had been changed. Exclosure experiments were started to distinguish grazing effects from effects of increased soil waterlogging caused by the neglect of the drainage system.Both vegetation surveys and permanent plots demonstrated a dichotomy in vegetation succession. The incidence of secondary pioneer vegetation dominated by Salicornia spp. and Suaeda maritima increased from 0 to 20%, whereas the late‐successional (Phragmites australis) vegetation from 10 to 15%. Grazing intensity decreased towards the sea. The grazed area contracted landward, which allowed vegetation dominated by tall species to increase seaward.Grazing and increased waterlogging interacted in several ways. The impact of trampling increased, and in the intensively grazed parts soil salinity increased. This can probably be explained by low vegetation cover in spring.Framework Ordination, an indirect‐gradient‐analysis technique, was used to infer the importance of environmental factors in influencing changes in species composition. Many changes were positively or negatively correlated with soil aeration and soil salinity, whereas elevation was of minor importance. Grazing accounted for only a few changes in species frequency. Changes in permanent plots were greater during the first than during the second half of the study period. In exclosures that were installed halfway through the study period, there was a relatively rapid recovery of previously dominant species that had decreased during the first half of the study period.Species richness per unit area in the reserve increased. At the seaward side of the marsh, the altered management allowed succession to proceed leading to establishment of stands of Phragmites australis, whereas on the landward side, the combination of moderate grazing with neglect of the drainage system appeared an effective measure in maintaining habitats for a wider range of halophytic species.
Effects of long‐term cutting in a grassland system: perspectives for restoration of plant communities on nutrient‐poor soils
Authors: Bakker J.P. , Elzinga J.A. , de Vries Y. 
Published: February 2009

Abstract. The upper courses of brook valley systems harbour Nardo‐Galion saxatilis communities characteristic of oligo‐trophic soils under low‐intensity farming. Most of these communities have disappeared under intensified farming i.e. application of fertilizers. We studied the possibilities of restoration i.e. re‐establishment of the former plant community by adopting various cutting regimes after the cessation of fertilization in 1972. The various cutting regimes revealed different effects after 25 yr. Regimes with cutting every second year with or without removal of the swath, and complete abandonment deviated from the other regimes that included annual haymaking with different frequency and timing. The latter group of cutting regimes came closer to the community of an adjacent field where fertilization stopped in 1967. This field in turn harboured several Nardo‐Galion species after 25 yr of annual cutting, and showed more resemblance with a local reference community (at a distance of 500 m) that had not been fertilized since the 1940s. The local reference still does not match poorly developed Nardo‐Galion saxatilis communities found in the region of ca. 50 km around the study area, and is far from well developed Nardo‐Galion communities in the same region.The study site still harbours several species characteristic of eutrophic soil and few species characteristic of oligotrophic soil after 25 yr of annual cutting and removal of the swath. The soil seed bank harbours only few target species. Although species characteristic of oligotrophic soil are present in an adjacent field and Nardo‐Galion saxatilis species occur at 500 m, they have not (yet) established in the target area.
The effects of cutting and herbicide treatment on Pteridium aquilinum encroachment
Authors: Pakeman R.J. , Thwaites R.H. , Le Due M.G. , Marrs R.H. 
Published: February 2009

Abstract. Pteridium aquilinum (bracken) encroachment is an important factor in the loss of certain habitats in the United Kingdom. However, no information exists as to whether prevention of encroachment is a cost‐effective strategy for Pteridium management. Conventional methods for the control of Pteridium (cutting, asulam application) were tested at one site (Levisham) to quantify their ability to prevent or delay encroachment and to affect the vigour of the Pteridium at the edge of the stand. The effects of encroachment and asulam application on the vegetation present were monitored at a second site (Ramsley), where techniques commonly used for moorland restoration were employed in combination with asulam application.Cutting once per year or a single application of asulam delayed the advance of the Pteridium front. At Levisham, the untreated front advanced 2.7 m in 5 yr, while in the same period the cut front advanced 0.88 m and the sprayed front was 1.5 m behind its initial position. At Ramsley, the untreated front invaded 1.8 m in 5 yr, and the sprayed front was again 1.5 m behind its starting position. Both spraying and cutting reduced frond biomass, frond cover and rhizome biomass. Herbicide spraying prevented the loss of Calluna vulgaris, though the restoration treatments had little effect. The merits of a balanced targeting of control on encroaching fronts or Pteridium at the stand level are discussed for different situations.
The impact of site conditions and seed dispersal on restoration success in alluvial meadows
Authors: Donath Tobias W. , Holzel Norbert , Otte Annette 
Published: February 2009

Abstract. We studied the restoration success of flood plain meadows in the northern Upper Rhine valley, where between 1988 and 1992, 35 ha of arable land was converted into grassland and subsequently managed for nature conservation.Remnant populations of typical alluvial meadow species were found in old meadows and along drainage ditches that dissect the whole area. We analysed the site conditions and phytosociological relevés in old and new meadows. Small differences in site parameters between old and new meadows contrasted with a clear floristic differentiation between the two meadow types. The vegetation of old meadows was much more differentiated along prevailing environmental gradients than the vegetation of new meadows. Despite the favourable site conditions for the re‐establishment of species‐rich meadows on the former arable land, restoration success was limited to the vicinity of remnant stands. In contrast to old meadows, indicator species of new grassland were still typical species of regularly disturbed ruderal and arable habitats, often capable of building up a persistent seed bank.The precise mapping of 23 target species revealed that even wind dispersal predominantly leads to re‐establishment in the close circumference of parent plants. We found no indication that regular flooding, hay‐making and autumnal grazing had an impact on recolonization of newly created grassland. Even under favourable conditions for the re‐establishment of target species, restoration success in alluvial meadows proved to be strongly dispersal limited. We discuss the implications of our findings for future restoration management in grasslands.
Effect of burning and mowing on grass and forb diversity in a long‐term grassland experiment
Authors: Fynn Richard W.S. , Morris Craig D. , Edwards Trevor J. 
Published: February 2009

Abstract. Disturbance may be an important determinant of plant community composition and diversity owing to its effects on competitive interactions, resources, dominance and vigour. The effect of type, timing and frequency of disturbance on grass and forb species richness was examined using data from a long‐term (> 50 yr) grassland burning and mowing experiment in KwaZulu‐Natal, South Africa.Grass species richness declined considerably (> 50%) in the absence of disturbance, whereas forb species richness was unaffected. Annual burning in sites not mown in summer tended to increase grass species richness relative to triennial burning (22% increase) with the reverse being true in sites mown twice in summer (37% decline). Forb species richness declined by 25% in sites mown twice in summer relative to sites mown in early summer only. Disturbance was necessary to achieve maximum grass species richness presumably by removing litter and increasing the availability of light. The interaction of time of mowing in summer (early versus late) and time of burning during the dormant period (spring versus winter) had the most dramatic effect on species richness. Time of burning had no effect on richness in sites mown in early summer, but winter burning resulted in a dramatic decline (27–42%) in richness in sites mown in late summer. This effect may be related to possible greater soil desiccation with this combination of disturbances.
Seedling recruitment on agriculturally improved mesic grassland: the influence of disturbance and management schemes
Authors: Hofmann Martina , Isselstein Johannes 
Published: February 2009

AbstractQuestion: Are the recruitment patterns of deliberately introduced wildflower species influenced by cutting frequencies and disturbance treatments? To what extent do these different treatments affect productivity and sward structure of an agriculturally improved grassland?Location: A mesic lowland grassland near Göttingen, Lower Saxony, Germany.Methods: Recruitment success of eight sown wildflower species was studied in a permanent grassland treated by a factorial combination of different pre‐sowing cutting intervals (1, 3 or 9 wk), post‐sowing cutting intervals (1,3 or 9 wk) and disturbance (control, harrowing, removal of sward). Seedling emergence and survival, biomass production and sward structure were followed over two years.Results: For most species seedling emergence was highest in the harrowing treatment. The complete sward removal did not further increase seedling emergence. Seedling survival was strongly influenced by the post‐sowing cutting frequency with highest mortality in the 9 wk cutting interval compared to one and 3 wk cutting intervals. Annual dry matter yield varied between 4.4, 5.9 and 9.4 t.ha‐1 in the 1,3 and 9 wk pre‐sowing cutting treatment, respectively. In June, when the seeds were sown, the tiller number of the 1 wk cut plots was twice as high as for the 9 wk cut plots and five times higher than in the harrowing treatment.Conclusions: Disturbance by harrowing provided the optimal environmental cues to trigger germination, whereas seedling survival was facilitated by increased light penetration due to frequent cutting. The investigation revealed the overriding importance of frequent standing crop removal in the early phase of seedling establishment on agriculturally improved grassland.
Large herbivores as mobile links between isolated nature reserves through adhesive seed dispersal
Authors: Couvreur Martine , Christiaen Bart , Verheyen Kris , Hermy Martin 
Published: February 2009

AbstractQuestion: Do large herbivores contribute to the dispersal of plant seeds between isolated habitats by epizoochory?Location: Nature reserves in Flanders, Belgium.Methods: Epizoochory was studied by brushing plant seeds from the fur of 201 domesticated large herbivores (Galloway cattle, donkeys and horses), grazing in 27 Flemish nature reserves. Several herbivores were examined after transport between different nature reserves as part of the seasonal grazing system in Flanders, allowing detection of seed dispersal both within and between reserves. The seedling emergence method was used to identify the dispersed plant species.Results: In total, 6385 epizoochorous seeds from 75 species germinated, yet the real seed quantity was underestimated by the seedling emergence method. A wide variety of seed morphology, seed weights and plant heights was represented among the dispersed species, many of which had a transient seed bank. There was a gradual turnover in epizoochorous species composition in the course of the vegetation season, and seed dispersal occurred both within and between different nature reserves.Conclusions: Domesticated large herbivores, as models for wild mammals in the present and the past, are important dispersers of many plant species. Through seasonal grazing, the herbivores function as ‘mobile link organisms’, connecting isolated nature reserves through seed dispersal, possibly influencing vegetation development and long‐term survival of plant populations. As such, large herbivores are important instruments in ecological restoration, especially in fragmented ecosystems.
Temporal and spatial patterns of ecosystem functioning in protected arid areas in southeastern Spain
Authors: Paruelo José M. , Piñeiro G. , Escribano P. , Oyonarte C. , Alcaraz D. , Cabello J. 
Published: February 2009

AbstractWe characterized the spatial variability and temporal dynamics of the photosynthetic active radiation absorbed (APAR) by the canopy, a descriptor of ecosystem functioning, in Cabo de Gata – Níjar Natural Park (CGNNP) (Spain). Ecosystem functioning was characterized for five landscape classes using the Normalized Difference Vegetation Index (NDVI) derived from NOAA/AVHRR LAC (1 km × 1 km) images. We also used a 19‐year time series of NDVI PAL data (8 km × 8 km) to analyse the relationship APAR‐precipitation inside and outside the park.The vegetation of CGNNP absorbed less than 20% of the incoming radiation. Plains intercepted 37% and hills 14% less photosynthetic active radiation than mountains, the most productive landscape of the park. CGNNP showed a well‐defined growing season with a unique peak of APAR. Plains and piedmont, covered by annual vegetation displayed an earlier development of the leaf area index than the shrublands and grasslands typical of the other landscapes. APAR had a significant relationship with the sum of the precipitation of the current and two previous growing seasons, except for the plains. We found that the APAR of the areas more modified by humans (outside the park) showed a lower sensitivity to changes in precipitation than those under protection. The differences were higher if the accumulated precipitation of the previous three growing seasons was considered. The description of such differences in the response of absorbed PAR to water availability are proposed as the base of a monitoring system for semi‐arid and arid areas.
Seedling recruitment in flood‐meadow species: The effects of gaps, litter and vegetation matrix
Authors: Hölzel Norbert 
Published: February 2009

AbstractQuestion: Is the failure of establishment of rare flood‐meadow species in habitat restoration primarily due to seed or microsite limitation? How do sown species respond to artificially created gaps and added litter at two neighbouring sites with similar physical conditions but contrasting vegetation matrix (young arable fallow field vs species‐poor meadow sward)?Location: Upper Rhine valley, southwestern Germany, 85 m a.s.l.Methods: Seeds of six typical flood‐meadow species were sown in four treatment combinations of the factors gap creation and litter addition. Seedling recruitment was monitored for three years.Results: Five of the six species established successfully at both sites largely irrespective of treatments, indicating seed limitation. Only in the small‐seeded Arabis nemorensis, which was revealed to be strictly gap‐dependent at the meadow site, could an obvious microsite limitation be shown. The non‐significance of gap treatments in all other species at the relatively high productive meadow site is probably due to biomass removal by mowing in early summer. Only at the extremes of the seed size spectrum did the results meet predictions of plant ecological theory, such as the strict gap dependence of small‐seeded species in closed swards or the positive to neutral response of large‐seeded species to litter layers.Conclusions: Species identity was revealed to be the major factor influencing differences in recruitment. Due to the lack of a general trend in the response towards treatments the results support conceptual models that describe the interplay of facilitation and interference as a highly dynamic equilibrium, driven by variable abiotic and biotic marginal conditions.