bluuebunny/crossref_metadata_2025 huggingface dataset:
Fire‐induced colonization of a Flooding Pampa grassland by thistles: Remnant litter and interference effects
Authors: Ortega Elizabeth , Laterra Pedro
Published: February 2009

Abstract. Winter and spring burnings constitute a traditional management practice of the Flooding Pampa grasslands which are dominated by the tussock grass Paspalum quadrifarium. In addition to increasing the primary productivity and the nutrient quality of the regrowth, this burning favours the establishment of opportunistic species, especially the legume Lotus glaber and the thistles Cirsium vulgare and Carduus acanthoides. The aims of the present study were to assess the effects of burning and those of the remnant litter on L. glaber and thistle recruitment, as well as the effects of L. glaber density on the emergence, survival and flowering of thistles. Two field experiments were carried out: 1. A completely randomized factorial design with occurrence of L. glaber and fire was applied in a mature Paspalum stand; 2. A completely randomized design with four L. glaber seed densities oversown on a burned Paspalum stand, as the treatments. Thistle and L. glaber recruitment within the Paspalum stand was dependent on fire, but their emergence in burnt plots was reduced by the presence of remnant litter. Remnant litter and interference from L. glaber provide complementary mechanisms to reduce fire‐cued colonization by thistles. While seedling emergence of thistles was mostly affected by the presence of remnant litter, seedling survival depended on local density of L. glaber. By the end of the first post‐fire growing season, the survivorship of established thistles was linearly reduced with increasing sowing density and above‐ground biomass of L. glaber. The maintenance of a significant litter coverage and a high density of L. glaber in the pre‐fire seed bank, as well as the oversowing of L. glaber after fire, may be useful tools in fire management of Paspalum stands aimed to improve their forage value with reduced dependence on chemical control of weeds.
Calibration of Ellenberg indicator values for the Faroe Islands
Authors: Lawesson Jonas Erik , Fosaa Anna Maria , Olsen Erla
Published: February 2009

Abstract. Elenberg's bio‐indication system for soil moisture (F), soil nitrogen (N) and soil reaction (R) was examined, based on 559 vegetation samples and environmental characteristics (vegetation cover, soil depth, soil moisture, chemical soil properties) from four Faroe islands. The original indicator values from central Europe were used for the calculation of weighted community indicator values of F, N and R. These were regressed with respect to environmental data, applying standard curvilinear regression and generalized linear modelling (GLM) and new predicted values of community indicator values were obtained from the best model. Faroe species optima values of 162 taxa for one or more of the three EUenberg scales were derived from fitting Huisman‐Olff‐Fresco (HOF) models of species abundance with respect to predicted community indicator values and are proposed as new EUenberg species indicator values to be used in the Faroe Islands. F was best correlated with a GLM model containing soil moisture, organic soil fraction, soil depth and total vegetation cover, R with a GLM model containing pH and calcium in % organic soil fraction, N with total phosphorus in % organic soil fraction. The calibrated species indicator scales are much truncated, as compared with the original values, resulting in significantly different overall distributions of the original and new species indicator values. The recalculated community indicator values are much better correlated to environmental measurements. Several species do not have clear optima, but linear or monotone relationships to the examined indicator scales. This probably indicates that the occurrence of some species in the Faroe Islands are either determined by factors other than moisture, pH or soil nutrient status or, given the young age and environmental instability of the islands, are governed by stochastic mechanisms. Extension of Ellenberg indicator values outside central Europe should always be carefully calibrated by means of adequate environmental data and adequate statistical models, such as HOF models, should be applied.
Restoration of the Cirsio dissecti‐Molinietum in The Netherlands: Can we rely on soil seed banks?
Authors: Matus G. , Verhagen R. , Bekker R.M. , Grootjans A.P.
Published: February 2009

Abstract. Vegetation and soil seed banks of a threatened Atlantic fen meadow community were studied using recent phytosociological records and seedling emergence from soil samples. Similarly managed but differently degraded stands that suffered different levels of species impoverishment were compared. The actual vegetation was related to a set of phytosociological references representing the subassociations of the community. DCA positions of reference relevés from the different subassociations were overlapping, suggesting that in all references many common species occur. Recent records were positioned in‐between the seed bank samples and the references. The soil seed banks of all stands were dominated by ordinary species. Most character species had at most sparse seed banks and no seedlings of locally extinct character species, mentioned in historic floristic records, were detected. In contrast species of pioneer and small‐sedge communities as well as those of heathlands were abundant in the seed banks. Based on the vertical distribution of seeds in the soil layers most fen meadow species were classified into transient or short‐term persistent seed bank types. We concluded that complete restoration of the Cirsio dissecti‐Molinietum without reintroduc‐tion is only likely in stands that were degraded only a few years ago. On the other hand, the presence of viable seeds of Nanocyperion and Parvocaricetea species is promising for the restoration of these communities even after decades. Recreation of pioneer habitats by sod cutting will preserve these species.
Mapping alpine vegetation based on image analysis, topographic variables and Canonical Correspondence Analysis
Authors: Dirnböck T. , Dullinger S. , Gottfried M. , Ginzler C. , Grabherr G.
Published: February 2009

Abstract. The objective of the present study was to map dominant plant communities of an alpine area in the northeastern Alps (Austria), based on computer modelling. We employed gradient analysis by means of Canonical Correspondence Analysis (CCA) as a prediction tool and image segmentation as a filter for reducing the number of incorrect predictions. Topographical variables reflecting relief properties at different scales were used as surrogates for environmental conditions in combination with spectral band values from infrared orthophotographs. Coupling topographic correlation using CCA and image analysis proved practicable to map the distribution of alpine plant communities. Although plant communities often showed similar spectral response, they were mapped according to their specific topographical niches. Generally, topographic variables, indicative of environmental gradients controlling plant distribution, provided this information in most cases. The importance of spectral vs topographic variables varied among plant communities. Whereas the correlation between topography and plant species distribution was particularly significant for mapping alpine grasslands, spectral texture measures proved to be of major importance in discriminating between pioneer communities. Post‐processing by image segmentation improved overall accuracy by 12%. A total of 17 plant communities and their mosaics were mapped, with an overall accuracy of 69.4% and a κ value of 0.64. Inaccuracy resulted from insufficient resolution of the available digital elevation model and confounding effects of additional controls like land use history, which could not be accounted for by topographic descriptors.
Seedling recruitment of Succisella inflexa in fen meadows: Importance of seed and microsite availability
Authors: Overbeck G. , Kiehl K. , Abs C.
Published: February 2009

Abstract. The effects of different forms of land use on germination and establishment of the rare fen species Succisella inflexa were investigated in seed introduction experiments in a mown and an abandoned fen meadow in SE Germany. Treatments included abandonment, mowing in fall and mowing with creation of gaps in the moss and litter layer. Floating capacity of seeds was tested in order to estimate potential dispersal by water.

On the mown meadow, gaps had a slightly positive effect on germination rates, while greatly increasing seedling survival until the next spring. At the abandoned site, litter inhibited germination, whereas mosses had a negative effect on germination and a positive effect on survival rates during the first year after germination. Both germination and seedling establishment were negatively affected by the presence of slug herbivores. On the abandoned site, no seedlings at all survived until the next spring. Even though seeds of Succisella inflexa were capable to float for several weeks and to germinate thereafter, the situation at the field sites indicates that longdistance dispersal is highly unlikely. Our results showed that not only direct effects of abandonment, such as accumulation of litter, may have led to poor germination and poor seedling establishment of the species. Additionally, indirect consequences of changes in land use, such as higher seedling herbivory by slugs and successional vegetation changes due to abandonment, were important in determining habitat quality and availability of microsites for seedling recruitment. Furthermore, early mowing imposed seed limitation on plant populations.
Vegetation succession in basalt quarries: Pattern on a landscape scale
Authors: Novák Jan , Prach Karel
Published: February 2009

Abstract. A spatio‐temporal variation of vegetation during spontaneous succession was studied in 56 basalt quarries spread over 1800 km2 in the České středohoří Hills (NW Czech Republic, Central Europe). Differences in the particular habitats inside a quarry, i.e. steep rocky slopes, bottoms and levels; dumps; and screes were considered. The habitats ranged in age from 1 to 78 yr since abandonment. Macroclimate (mean annual temperature and precipitation) significantly influenced the course of succession, which led to a formation of shrubby grassland, shrubby woodland or tall woodland. Participation of target species typical of steppe‐like communities significantly depended on the occurrence of the communities in the vicinity, up to a distance of 30 m from a quarry. Disused quarries may become refugia for rare plant species. Spontaneous successional processes led in the reasonable time of ca. 20 yr to semi‐natural vegetation. Thus, they can be successfully exploited in restoration programs scheduled for the disused quarries.
Heathland restoration in The Netherlands: Effects of turf cutting depth on germination of Arnica montana
Authors: van der Berg Leon J.L. , Vergeer Philippine , Roelofs Jan G.M.
Published: February 2009

Abstract. Germination experiments were conducted in a heathland after turf cutting and in a climate chamber to investigate the effects of turf cutting depth, aluminium toxicity and aluminium detoxification by humic acids and base cations on the germination and establishment of Arnica montana. Turfs were cut at three different depths, creating a gradient from organic to mineral soils. Germination and establishment of A. montana were negatively correlated with turf cutting depth. The removal of organic matter resulted in a major decrease in organic fraction of the soil and its nutrients. It also resulted in a considerable decrease in moisture content and humic acids. Additional liming after turf cutting increased germination and establishment in all plots and at all depths.

Germination experiments under controlled conditions in a climate chamber revealed a significantly higher germination at low aluminium/calcium (Al:Ca) ratios. High Al:Ca ratios resulted in poor germination, suggesting Al toxicity. Addition of humic acids increased germination, even at high Al:Ca ratios, suggesting immobilization of Al by humic acids.

It is concluded that turf cutting can have a marked effect on the success of heathland restoration. It results in the intended removal of the eutrophic layer but also in the unintentional removal of much of the buffering mechanisms and/or Al immobilizing compounds. Additional buffering and/or less deep turf cutting may be necessary to allow germination and establishment of rare herbaceous species such as A. montana.
Spontaneous succession in Central‐European man‐made habitats: What information can be used in restoration practice?
Authors: Prach Karel
Published: February 2009

Abstract. The results of previous studies concerning spontaneous vegetation succession in various man‐made or disturbed habitats in Central Europe are discussed in relation to restoration ecology. An attempt is made to answer the main questions which are important to restoration programs. These concern the rate and direction of succession; participation of target species and communities, woody species, ruderals and aliens; arresting or diverting succession; changes in species diversity; variability of successional pathways and the role of abiotic environmental conditions. The great potential for using successional theory in restoration programs is emphasized.
Restoration of a species‐rich flood meadow by topsoil removal and diaspore transfer with plant material
Authors: Hölzel Norbert , Otte Annette
Published: February 2009

Abstract. In previous studies, limited dispersal was revealed to be the main obstacle to restoration of species‐rich flood‐meadows along the northern Upper Rhine in Germany. To overcome dispersal limitation we transferred freshly mown plant material from species‐rich sources to a restoration site on a former arable field. Before plant material application, topsoil was removed to accelerate nutrient impoverishment and create favourable conditions for seedling recruitment.

Topsoil removal led to a drastic reduction in organic matter and essential mineral nutrients to the level of target communities (P) or even below (N, K). At a removal depth of 30 cm content of the soil seed bank that comprised exclusively of annual arable weeds, ruderals and some common grassland species, declined by 60 ‐ 80%, while at a removal depth of 50 cm the seed bank was almost completely eliminated. With few exceptions, all species recorded in source plant material were found established at the restoration site. However, the overall correlation between seed content in plant material and establishment success was not very high.

Vegetation development at the restoration site was characterized by a rapid decline in arable weeds and ruderals, while resident grassland species and species transferred with plant material increased rapidly from the third year onwards. After four years as many as 102 species were established that could be exclusively attributed to plant material transfer, among them many rare and highly endangered plants. Establishment of species from plant material was most successful in regularly flooded plots, due to the suppression of competitors as well as the creation of favourable moisture conditions for seedling emergence.

Diaspore transfer with plant material proved to be an extremely successful method in restoring species‐rich grassland. However, high quality of plant material and suitable site conditions with low competition in early stages of succession seem to be essential prerequisites.
An attempt to restore a central European species‐rich mountain grassland through grazing
Authors: Matějková Ivona , van Diggelen Rudy , Prach Karel
Published: February 2009

Abstract. This paper describes the effects of re‐establishing seasonal cattle grazing by 0.7 animal.ha‐1 on vegetation in a long‐term abandoned, and partly degraded, semi‐natural mountain pasture in the Šumava National Park, Czech Republic. There was very uneven grazing intensity inside the locality, and grazing preference changed during the season: cattle grazed most of the time in productive but species‐poor Deschampsia cespitosa swards, but changed to a species‐rich Violion caninae stand in the middle of the summer. A species‐rich Carex rostrata community was only grazed at the end of the season. Species‐poor swards dominated by Nardus stricta and Carex brizoides were mainly used as resting areas. Both grazing and excluding from grazing had a negative effect on species diversity of the Deschampsia cespitosa swards. The soil seed bank contained only few species that are characteristic of mountain grassland communities, and seed dispersal of the target species by cattle dung was also found to be very limited. Thus both grazing and exclusion from grazing are probably of limited value for the restoration of species‐rich grasslands from species‐poor Deschampsia cespitosa swards in this case.
Restoration of ditch bank plant species richness: The potential of the soil seed bank
Authors: Blomqvist M.M. , Bekker R.M. , Vos P.
Published: February 2009

Abstract.Small‐scale landscape elements, such as ditch banks, play an important role in preserving plant species richness in agricultural landscapes. In this study, we investigate whether the seed bank might be useful for restoring the above‐ground plant species richness. We studied the vegetation and seed bank composition at six species‐rich and six species‐poor ditch banks, where agri‐environment schemes are running to maintain and enhance ditch bank plant diversity. We show that the number of species in the seed bank was low, regardless of the number of species in the established vegetation. Moreover, the seed bank was always dissimilar to the established vegetation. Target species for nature conservation were occasionally present in the seed bank at both species‐poor and species‐rich sites, but rarely so if the species was absent from the established vegetation. We conclude that the potential use of the seed bank for restoration of ditch banks is minimal. At present, plant species richness seems to be largely controlled by germination opportunities; high biomass and competition appear to hamper germination at species‐poor sites. We recommend continued nutrient reduction at such sites. Soil disturbance measures and deliberate sowing should also be considered.
Effects of restoration treatments on the diaspore bank under dense Pteridium stands in the UK
Authors: Ghorbani J. , Das P.M. , Das A.B. , Hughes J.M. , McAllister H.A. , Pallai S.K. , Pakeman R.J. , Marrs R.H. , Le Duc M.G.
Published: February 2009

Abstract. The diaspore bank (seeds of higher plants and spores of ferns and bryophytes) was assessed between 3 and 5 yr after experiments to control Pteridium aquilinum (bracken) and restore appropriate vegetation were initiated at two contrasting locations in the UK. We tested the response of the diaspore bank using univariate and multivariate analysis of variance. The two approaches were complementary and together improved the interpretation of these results. There were considerable differences in the diaspore banks of the two sites and among the experimental locations within sites. Within each experiment there were differences in species composition, with species that were (1) common to both diaspore bank and vegetation, (2) restricted to the diaspore bank and (3) restricted to the vegetation. There is a possibility of increasing the biodiversity of the developing vegetation if some of the species present in the diaspore bank can be germinated. This was especially true for ferns where four species were found in the spore bank which were not present in the vegetation. There were few significant effects of management treatment on the diaspore bank as the experiments had been in progress for only 3 to 5 yr, but a few species had different densities in the different treatments (Betula pubescens, Juncus effusus and some bryophytes). The greatest correlation between vegetation and diaspore bank was found at the top hierarchical level (entire dataset) and this progressively reduced with scale. We interpret this as a landscape/species pool effect: as the scale of the study reduces the correlation between diaspore bank and vegetation also reduces, at least over the time scale of our study. The relevance of these results for restoration ecology is discussed briefly.
Site‐specific responses of native and exotic species to disturbances in a mesic grassland community
Authors: Hayes Grey F. , Holl Karen D.
Published: February 2009

Abstract. Grassland communities are increasingly recognized as disturbance‐dependent ecosystems, yet there are few replicated, multi‐site studies documenting vegetation responses to varying frequencies and types of grassland disturbance. Even so, land managers frequently manipulate disturbance regimes in an attempt to favour native grassland plants over exotic species. We conducted a factorial experiment testing three frequencies of clipping combined with litter accumulation, litter removal, and soil disturbance within the highly threatened California coastal prairie plant community. We monitored the response of native/exotic, grass/forb plant guilds once a year for four years. More frequent clipping reduced cover of exotic grasses and favoured exotic forbs, whereas native species were largely unaffected by clipping frequency. Litter accumulation, litter removal, and soil disturbance did not affect vegetation composition. Effects of litter accumulation may take longer than our experiment allowed, and soil disturbance due to our treatments was not sufficiently strong to show consistent effects relative to mammalian soil disturbance. Treatment response of some plant guilds differed among sites, highlighting the importance of replicating experiments at several sites before recommending conservation management practices.
Effects of cessation of grazing on leaf‐level photosynthesis of Periploca laevigata
Authors: Castro H. , Nabais C. , Alados C.L. , Freitas H.
Published: February 2009

Abstract. The impact of grazing pressure on gas exchange of Periploca laevigata was studied in relation to its nutritional status. P. laevigata, a woody and highly palatable shrub, is an important forage species in the dry season in Cabo de Gata Natural Park (Almeria, SE Spain) where this study was carried out. Seasonal and diurnal courses of net photosynthesis, transpiration and stomatal conductance were measured in the field. In addition, soil and plant nutrient status were measured as potential factors influencing leaf photosynthetic levels. Early in the growing season, ungrazed P. laevigata had higher photosynthetic activity than grazed plants suggesting that the defoliated plants were still recovering from herbivore damage in the previous summer. Later in the growing season grazed P. laevigata had higher photosynthetic activity than ungrazed plants, suggesting higher metabolic activity and a possible investment in chemical defences. Concentrations of P and N in the soil were higher in the grazed area. The nutrient concentration of the leaves of P. laevigata was similar in grazed and ungrazed plants.
Using plant traits to compare sward structure and composition of grass species across environmental gradients
Authors: Duru M. , Cruz P. , Magda D.
Published: February 2009

Abstract. Plant traits which may give an indication of a plant's strategy for nutrient acquisition and regeneration are known for numerous grassland species. This study aimed to establish whether there is any relationship between two plant traits: specific leaf area (SLA) and number of reproductive tillers, and sward structural characteristics which influence herbage intake by grazers (bulk density and digestibility, leaf:stem ratio). Comparison is made for nutrient‐rich (Dactylis glomerata) and nutrient‐poor (Festuca rubra) grass species. We hypothesized that these traits are responsive to environmental gradients and also act on the processes of the ecosystem. Both grasses were compared with two P‐fertilizer rates in two localities (200 and 1300 m a.s.l.) which differed in their temperature:radiation ratios. For the vegetative phase SLA was well correlated with sward characteristics: D. glomerata, which has the higher SLA, has the lower bulk density and higher digestibility. The values of SLA and vegetation bulk density varied according to growing conditions (P‐rate and temperature:radiation ratio), but the ranking of the species remained the same because the phenotypic plasticity that exists for plant traits was also observed for sward structure and composition. That suggested the possibility of grouping natural grassland species for their relevant characteristics for grazers according to SLA values. Over the reproductive phase, the proportion of stems was well correlated to the percentage of reproductive tillers. However, the percentage of reproductive tillers was a very plastic trait for both species, depending on the growing conditions, and resulting in a density‐dependent effect, particularly for F. rubra. The species studied were too plastic and too similar in their regenerative strategy so that there is no unique relationship between percentage of reproductive tillers and stem proportion, regardless of the species and the growing conditions. The number of reproductive tillers is not a suitable plant trait which could be used to rank species for leaf and stem proportions in the sward.
Spatial analysis of anthropogenic disturbance regimes and roadside shrubs in a fragmented agricultural landscape
Authors: Spooner Peter G. , Lunt Ian D. , Briggs Sue V.
Published: February 2009

Abstract. In fragmented woodlands in agricultural regions of Australia, roadside environments (road verges) provide important refuges for threatened native fauna and isolated populations of plant species. However, as roads are transport corridors for humans and their vehicles, species survival is affected through destruction, fragmentation and modification of remaining habitat by human activity. Few studies have recognised the effects of anthropogenic disturbances, in the form of historical roadworks activities, on adjacent roadside plant populations. The aim of this study was to investigate the effects of soil disturbance from roadworks on the spatial patterns and structural dynamics of roadside Acacia populations in an agricultural area in southeastern Australia. Stem size and disturbance data were collected from 135 roadside populations of three species of Acacia shrubs in the Lockhart Shire area. Spatial pattern analysis using the Network K‐function and Discriminant Function analyses showed that road verge width, road category, disturbance intensity and distance to nearest town were highly significant variables in relation to disturbance from roadworks and shrub structural dynamics. Colonising populations were more abundant along gravel roads where soil disturbance intensity was high, whereas stable populations were more abundant where soil disturbance intensity was low. Senescent populations were more abundant in narrow, little used road verge corridors 4–6 km from nearby towns. These results suggest that anthropogenic disturbance regimes may be critical to shrub recruitment and persistence in roadside environments, which has important consequences for conservation of threatened native flora and fauna in agricultural landscapes.
Seashore disturbance and management of the clonalArctophila fulva: Modelling patch dynamics
Authors: Rautiainen P. , Laine A.‐L. , Aikio S. , Aspi J. , Siira J. , Hyvärinen M.
Published: February 2009

Question:What is the population viability of a critically endangered seashore grass,Arctophila fulvavar.pendulina.

Location:Liminka Bay, W Finland, 25°21′70 N, 64°51′90 E.

Methods:We constructed a matrix population model based on colonization and disappearance events and patch size changes ofA. fulva.Patches were divided into hydric and non‐hydric zones according to proximity to the seashore and intensity of disturbance. Perturbation analyses were carried out in order to identify transitions critical for population growth. Seed bank and seed germination studies provided background information for the model design.

Results:A. fulvapatches observed in the more disturbed hydric zone (closest to the sea) increased in number, as did the total number of patches. However, the number of patches in the less disturbed non‐hydric zone decreased.

Conclusions:Short‐term dynamics of theA. fulvapopulation at Liminka Bay seem to be determined by environmental fluctuations, which cause annual variation in transition rates between patch size classes. The long‐term dynamics are probably governed by initiation of primary succession by isostatic land uplift. Increased disturbance at the water's edge may promote persistence ofA. fulvathrough reduced interspecific competition. Our results suggest that shoreline disturbance of the hydric zone is sufficient for maintaining a viable population. Competitive exclusion ofA. fulvain the non‐hydric zone may be delayed by management practices, such as mowing.
Effects of restoration measures on plant communities of wet heathland ecosystems
Authors: Jansen A J.M. , Fresco L.F.M. , Grootjans A.P. , Jalink M.H.
Published: February 2009

Question: Which are the success and failure of restoration measures, particularly sod‐cutting and hydrological measures, in small wetlands on mineral soils in The Netherlands.

Location: Twente, in the eastern part of The Netherlands.

Methods: Success or failure of restoration measures has been assessed by comparing experimental plots with that in reference plots for (1) species richness, (2) re‐establishment of endangered species and (3) species composition, including life forms and Red List species. In total 119 samples were taken in 42 permanent plots in fen meadows, small‐sedge marshes, wet heathlands, and soft‐water pools. Topsoil samples were analysed for pH, Ca, Mg, Na, K and Cation Exchange Capacity. Gradient analysis was carried out by means of Canonical Correspondence Analysis.

Results: Sod‐cutting, in combination with re‐wetting measures (infilling of ditches and drains), led to restoration of communities of soft‐water pools and small sedge marshes within five years. This rapid recovery is probably related to the presence of persistent seed banks of the component species of these communities. Complete restoration of fen meadows took longer (10–15 yr). Apparently, many species of fen meadows have short‐lived seed banks. Sod‐cutting of a degraded wet heathland and a soft‐water pool was only successful temporarily, probably as a consequence of low water tables.

Conclusions: To prevent depletion of (persistent) soil seed banks, sod‐cutting in nutrient‐poor wetlands is not recommended in areas where the groundwater regime and the base status of the soil can not be restored to levels required by plant communities of wet heathlands.
The influence of seed addition and cutting regime on the success of grassland restoration on former arable land
Authors: Lawson Clare S. , Ford Martin A. , Mitchley Jonathan
Published: February 2009

Questions: Can seed addition enhance the success of establishing species‐rich grassland on former arable land? Are sowing date and cutting regime important in determining success?

Location: Aberdeen and Elgin, northeast Scotland, United Kingdom. Methods: A field experiment was conducted at two sites to assess the effect of seed addition, sowing date and cutting regime on the vegetation developing on former arable land, the aim being to compare the success of different treatments at producing a species‐rich grassland.

Results: Sowing a seed mix resulted in the establishment of vegetation very distinct from the species‐poor vegetation dominated by perennial grasses which otherwise developed, though establishment success of the sown grassland species was highly variable between sites. Where establishment of the sown species was poor, sowing date had no significant effect on species composition, whereas the cutting regime was very important. Cutting the vegetation significantly increased both the number and abundance of sown species compared with the uncut control. Conversely, where establishment had been good, the cutting regime in the first year had little effect on species composition. Cutting the vegetation at least twice a year appeared to be the most effective management over the length of the experiment.

Conclusions: Sowing a seed mixture significantly reduced the abundance and number of naturally colonising species, effectively controlling problem weed species such as Senecio jacobaea and Cirsium vulgare, highlighting the agronomic value of sowing seed mixtures on fallow farmland. The sowing of a seed mix on former arable land has demonstrated that it is feasible to create vegetation similar in character to that of species‐rich grasslands.
Long‐term compositional responses of a South African mesic grassland to burning and mowing
Authors: Fynn Richard W.S. , Morris Craig D. , Edwards Trevor J.
Published: February 2009

Question: What is the long‐term compositional response of grass and forb species to various combinations of burning and mowing? Can these responses be predicted from simple plant traits?

Location: Ukulinga research and training farm (24°24′E, 30°24′S), Pietermaritzburg, KwaZulu‐Natal, South Africa.

Methods: Grass species relative abundance in 1996 in various burning and mowing treatments of a long‐term (> 50 a) experiment was calculated from data obtained using a point sampling method, whereas forb species abundance in 1999 was determined using the importance score method. The experiment consisted of different frequencies (annual, biennial and triennial) of burning and mowing in winter or spring in combination with different frequencies of summer mowing (none, early, late or both).

Results: Grasses responded to the type of disturbance (burn or mow) and frequency of burning, whereas forbs responded primarily to the presence or absence of any form of disturbance and secondarily to the timing of burning (spring versus winter). Summer mowing and annual or biennial dormant‐period burning maintained communities dominated by short grasses, whereas tall grasses dominated under annual dormant‐period mowing, triennial burning or protection from disturbance. Grass tillering strategy (below‐ or above‐ground) influenced response to burning frequency. Many erect herbaceous dicot species with aerial meristems were reduced in abundance by summer mowing whereas most small creeping herbaceous dicot species appeared to be dependent upon summer mowing.

Conclusions: This long‐term experiment demonstrated that: (1) grasses and forbs responded differently to burning and mowing; (2) simple plant traits, such as height, position of tiller initiation, and position of meristems have potential for predicting the response of species to the timing and frequency of burning and mowing.
Modelling the effects of human activity on the vegetation of a northeast Mediterranean island
Authors: Tzanopoulos Joseph , Mitchley Jonathan , Pantis John
Published: February 2009

Abstract. Question: Which factors affect the spatial variation of maquis and phryganic vegetation and how can the role of human activities be estimated through degradation models.

Location: Island of Sifnos, Cyclades, Greece.

Methods: Data on woody vegetation, environmental conditions and intensity of human activity were collected by field survey. The vegetation data were analysed using TWINSPAN. Models based on the combination of Canonical Variate Analysis and logistic regressions were used in order to examine and describe the different pathways of maquis degradation.

Results: The spatial variation of maquis and phryganic vegetation was related to both environmental and disturbance factors. The replacement of maquis by phryganic vegetation can follow two different pathways which reflect differences on the environmental conditions. However, the pathways themselves are determined by the combinations and levels of disturbance only.

Conclusion: Degradation models can provide essential information on the effects of human activities on the vegetation. Maquis vegetation is relatively tolerant of disturbance, however, if disturbance exceeds certain critical thresholds, maquis is replaced by phryganic vegetation. The presence of phryganic vegetation is not always the result of maquis degradation.
Implications of 19th century landscape patterns for the recovery ofFagus crenataforests
Authors: Ohtani Shinya , Koike Fumito
Published: February 2009

Questions:What is the effect of the 19th century (pre‐industrialization) landscape pattern on the recovery of climax forests in cool‐temperate mountain areas dominated byFagus crenata(Japanese beech)?

Location:Secondary forests on Mt. Daisen, western Japan.

Methods:Vegetation patterns before and after industrialization were obtained from maps drawn in 1898 and 1979. Tree measurements were made in 12 plots in 1997. Correlation between currentFagus crenatadominance and forest edge in the 19th century was analysed using an S‐shaped regression curve.Fagusjuvenile density was counted in the plots, and distances from each plot to the five nearest mother trees were measured to determine the dispersal kernel.

Results:Secondary grassland covered a substantial area in 1898, whereas forest covered most of the area in 1997.Faguswas dominant in places in the interior forest 100 years ago, and matureFagustrees were absent in secondary forests that had been grasslands in 1898. The expected number of juveniles decreased to one individual per 100 m2at 43.5 m from the mother tree.

Conclusions:The pre‐industrialization landscape greatly affected recovery ofFagusforest. Forests found on the 1898 vegetation map might have acted as refugia forFagus.The limited dispersal ability ofFagussuggests that it would take many generations (several hundred years) forFagusforests to recover at the centre of what had been grasslands in the 19th century.
Ground vegetation in the Mongolian taiga forest‐steppe ecotone does not offer evidence for the human origin of grasslands
Authors: Dulamsuren Ch. , Hauck M. , Mühlenberg M.
Published: February 2009

Question: Is the vegetation of meadow and mountain steppes distinct from the ground vegetation of light taiga forests in the transitional zone between these biomes?

Location: Western Khentey Mountains, northern Mongolia.

Methods: Vegetation was recorded from 100‐m2 plots from all dominant types of light taiga forest and dry grassland. Distinctness of ground vegetation was studied with Detrended Correspondence Analysis (DCA).

Results: Ground vegetation in the light taiga was significantly different from the herbal vegetation of meadow and mountain steppes. Clear separation was only absent for the Car ex amgunensis meadow steppes that occur in a narrow strip along the forest edge and are partly shaded by trees. Forest and steppe communities followed a moisture gradient according to the DCA ordination with light taiga forests at the moistest sites and steppe communities at the driest sites. Ulmus pumila open woodlands diverged from this pattern, because of their close spatial and phytosociological relationship to mountain steppes.

Conclusions: The present results do not support the assumption that grasslands in Mongolia's transitional zone between forest and steppe would generally resemble the ground vegetation of light taiga forests. This contradicts a published hypothesis stating that the vegetation of meadow and mountain steppes would not clearly differ from ground vegetation of light taiga forests in the forest‐steppe transitional zone of Mongolia.
Impact of prescribed burning on the nutrient balance of heathlands with particular reference to nitrogen and phosphorus
Authors: Niemeyer T. , Niemeyer M. , Mohamed A. , Fottner S. , Härdtle W.
Published: February 2009

Question:Can prescribed winter burning compensate atmospheric nutrient loads for dry heathlands? What effects does prescribed burning have on nutrient balances, particularly as regards the limiting nutrients N and P?

Location:Lueneburg Heath, NW Germany.

Methods:In two burning experiments (in 10/15 year oldCalluna‐stands) nutrient balances (for N, Ca, K, Mg, P) were calculated by analysing nutrient inputs (atmospheric deposition, ash deposition), nutrient stores (above‐ground biomass, organic horizon) and nutrient outputs (biomass combustion, leaching).

Results:Atmospheric nutrient deposition amounted to 22.8 kg.ha‐1.a‐1for N and < 0.5 kg.ha‐1.a‐1for P. Nutrient stores in the above‐ground biomass were 95/197 kg.ha‐1for N and 5/13 kg.ha‐1for P (first/second experiment, respectively). From these stores 90/53% (for N) and 25/14% (for P) were removed by burning. Effects of leaching on nutrient balances were low. In the first two years after burning, leaching rates of N increased by about 4/6 kg.ha‐1, whereas leaching rates of P did not change significantly. Input/output‐ratios showed that prescribed burning leads to positive nutrient balances for N, Ca and Mg in the long term. For example, the amounts of N removed by prescribed burning are equivalent to ca. five years of atmospheric inputs. Applied in ten‐year cycles, this measure alone cannot prevent N accumulation in the long term.

Conclusion:Regarding 10/15 year oldCalluna‐heaths, we assume that prescribed burning cannot compensate for atmospheric N inputs, thus making long‐term changes in the nutritional state inevitable. Therefore, prescribed burning should be applied in combination with high‐intensity management measures.
Developing a blueprint for conservation of the endangered longleaf pine ecosystem based on centers of Coastal Plain plant endemism
Authors: Sorrie Bruce A. , Weakley Alan S.
Published: February 2009

Question: Can the geographic patterning of endemic plant species inform reserve selection in a region of high endemism?

Location: The Southeastern Coastal Plain of North America, focusing primarily on the imperiled longleaf pine (Pinus palustris P. Miller) ecosystem.

Methods: We documented the high level of plant endemism in the region, and characterized the endemic taxa into distributional subregions.

Results: A total of 1630 plant taxa are endemic to the Coastal Plain, a large proportion of which are endemic to phytogeographical subregions within the Coastal Plain, with particularly large numbers of narrow endemics occurring in the East Gulf Coastal Plain and Florida Peninsula.

Conclusions: This pattern of local endemism presents challenges in conserving the full biota of the region: a reserve system focusing on few and large conservation areas has theoretical benefits for long‐term management and viability, but will fail to capture many local endemics. We propose that the dispersed distribution of endemic species will require a mixture of large core reserves and smaller satellite reserves.
Patterns of herbaceous plant diversity in southeastern Louisiana pine savannas
Authors: Keddy P.A. , Smith L. , Campbell D.R. , Clark M. , Montz G.
Published: February 2009

Question: How diverse are Louisiana pine savanna plant communities and how is diversity affected by time since burn and removal of a competitively dominant species?

Location: Lake Ramsay, southeastern Louisiana, USA.

Methods: Species‐area curves were constructed from nine nested quadrats in open savanna differing in time since burn (6, 18 and 30 months). Species frequency was determined for 100 1 ‐m2 quadrats. The dominant gras s, Andropogon virginicus, was removed with herbicide from moist and dry sites to test for possible effects of competition.

Results: Slopes of log‐log species‐area relationships were steep (0.195 to 0.379). Time since burn did not affect the richness of herbaceous plants, only woody species. More than half of all species recorded (43/79, 54%) were infrequent (in < 10% of quadrats). After two years, there were no differences in species richness and composition for plots with and without A. virginicus.

Conclusions: The high species diversity is typical of other savannas across the coastal plain. The large number of infrequent species indicates that the core‐satellite pattern of species occurrence found in temperate grasslands does not apply to southern pine savannas. The absence of effects due to removal of a dominant may be due to insufficient observation time, or low competition. Most species have traits, such as diminutive life forms, that suggest they are weak competitors for light in the presence of robust matrix grasses and in the absence of fire. Many species in Pinuspalustris savannas are likely either fugitive or peripheral species.
Natural disturbances and the physiognomy of pine savannas: A phenomenological model
Authors: Gilliam Frank S. , Platt William J. , Peet Robert K.
Published: February 2009

Abstract.Question:The decline of thePinus palustrisecosystems has resulted from anthropogenic influences, such as conversion to pine plantation forestry, agriculture and land development, all of which are closely related to increases in human populations. Other effects, however, have arisen from alterations in disturbance regimes that maintain the structure and function of these ecosystems. How have alterations of the disturbance regime altered the physiognomy of ‘old‐growth’ stands, and what are the implications for ecosystem conservation and restoration?

Methods:In contrast to models that emphasize close interactions among the vertically complex strata, we develop a conceptual phenomenological model for the physiognomic structure ofPinus palustrisstands. We relate two natural disturbances (tropical storms and fire) that affect different stages of the life cycle to different aspects of the physiognomic structure. We then compare overstorey stand structure and ground cover composition of two old‐growth longleaf stands near the extremes of different composite disturbance regimes: the Wade Tract (frequent hurricanes and fire) and the Boyd Tract (infrequent hurricanes and long‐term fire exclusion).

Results:We predict that tropical storms and fires have different effects on stand physiognomy. Tropical storms are periodic, and sometimes intense, whereas fires are more frequent and less intense. Hurricanes directly influence the overstorey via wind‐caused damage and mortality, and indirectly influence the herb layer by altering the spatial distribution of shading and litter accumulation. Fire exerts direct effects on juvenile stages and indirect effects on the herb layer via fine fuel consumption and selective mortality of potential competitorsof P. palustrisjuveniles. These differences in effects of disturbances can result in widely different physiognomiesfor P. palustrisstands. Finally, some global climate change scenarios have suggested that changes may occur in tropical storm and fire regimes, altering frequency and severity. Such changes may greatly affect pine stands, and ultimately entire pine savanna ecosystems.

Conclusions:Our phenomenological model of disturbance regimes inPinus palustrisold‐growth produces very different physiognomies for different disturbances regimes that reflect natural process and human management actions. This model can be used to derive restoration strategies for pine savannas that are linked to reinstitution of important ecological processes rather than specific physiognomic states.