Long‐term effects of mulching,traditional cutting and no management on plant species composition of improved upland grassland in the Czech Republic

A shortage of available livestock for utilizing grassland biomass in Central Europe is challenging for the management of both semi‐natural grasslands and previously intensified (limed, fertilized and reseeded) upland grasslands. An alternative method of grassland management is mulching, in which aboveground biomass is cut, crushed and subsequently spread on the surface. This paper reports on an experiment to compare three different mulching frequencies (one, two and three times per year) with an unmanaged treatment and traditional management of two cuts per year (control) on a previously improved upland meadow. Plant species composition was monitored over 13 years. Traditional management of two cuts with biomass removal was the most suitable method for maintaining plant species richness and diversity, and both were reduced significantly in the once‐mulched and especially in the unmanaged treatment. Tall dicotyledonous weeds such as Urtica dioica, Cirsium arvense and Aegopodium podagraria were promoted by the unmanaged treatment and by mulching once a year. Higher frequency of defoliation had positive effects on the spread of short forbs such as Taraxacum spp., Plantago lanceolata and Trifolium repens. After eight years, there were changes in sward structure in the unmanaged and mulched‐once‐a‐year treatments, with increase in the tall/short species ratio. In conclusion, repeated mulching cannot substitute fully for traditional two‐cut management in improved upland meadows without decreasing plant species richness and diversity, and changing the sward structure. Although mulching once a year may prevent invasion by shrubs and trees, it also supports the spread of weedy species similar to no management.     

The extent of semi-natural grassland communities in lowland England and Wales: a review of conservation surveys 1978–96

The extent of semi-natural grassland has diminished considerably across lowland landscapes of England and Wales during the second half of the twentieth century. Locating, describing and evaluating the dwindling cover has been a major challenge for conservationists. A concentrated vegetation survey effort at grassland sites has been mounted within different parts of Britain since the late 1970s. Plant community recognition has benefited considerably from the development of the contemporary National Vegetation Classification, and its widespread adoption permits national inventory of comparable vegetation data. Findings of a range of surveys (ninety-eight in total), undertaken between 1978 and 1996 in England and Wales covering different forms of unimproved lowland grassland, are collated and reviewed. Vegetation data were abstracted from internally published survey reports. Calcicolous and neutral grasslands have been covered more thoroughly than acidic and wet or marshy grasslands. Cover data are summarized at community level. Overall estimates from survey results indicate that there are some 27 500–40 000 ha of calcicolous grassland, 7500–15 000 ha of unimproved neutral pasture and hay meadow, 8000–15 000 ha of acidic grassland and 9000–17 500 ha of wet grassland in lowland England and Wales; these represent only 1–2% of the cover of permanent lowland grassland. Some communities have additional representation in heathlands, mires and upland environments. Although they require further refinement, the cover data for individual communities provide a context for assessing priorities in site-based and agri-environment conservation programmes. It is concluded that, as well as arresting further depletion, it will be necessary to restore and expand lowland grassland habitats to counteract the negative impacts of fragmentation and isolation of various community types, such as the Centaureo–Cynosuretum, which is widely but thinly distributed. Habitat rehabilitation schemes also need to assimilate local patterns of community diversity characteristic of both wet and dry grasslands. It is suggested that reversal of the recent successional trends that followed relaxation of grazing at certain sites might produce a more appropriate balance in the relative cover of coarse tall grasslands and fine short turf. Vegetation surveys provide a source of spatial data for identifying local aggregations of semi-natural grassland remnants.     

Effects of long‐term grazing management on dandelion (Taraxacum officinale) in Agrostis capillaris grassland

Dandelion (Taraxacum officinale agg.) is a common forb species in grasslands in Europe. Although sometimes regarded as a valuable forage herb, it may become a weed, especially in arable land. There is limited information on the response of Taraxacum to long‐term grassland management practices. Therefore, we analysed cover and dry‐matter standing biomass of Taraxacum in a long‐term (1998–2012) grazing experiment on an Agrostis capillaris grassland. The following treatments were laid out on formerly abandoned grassland: (i) intensive grazing (IG); (ii) extensive grazing (EG); (iii) first cut followed by intensive grazing (ICG); (iv) first cut followed by extensive grazing (ECG); and (v) unmanaged grassland (U). During the first 10 years, all defoliation treatments (i–iv) supported the presence of Taraxacum, and the lowest proportion was recorded in the unmanaged treatment (U). During the final 7 years of the study, combined cutting and grazing promoted Taraxacum cover more than that of grazing only (ICG > IG > ECG > EG). Cover of Taraxacum was negatively affected by increasing sward height where Taraxacum plants had lower fitness. Due to the relatively strong relationship between percentage cover of Taraxacum and its dry‐matter biomass, percentage cover could be used as a simple method for the assessment of biomass of Taraxacum in a sward. Results are discussed in the context of adapting the management of A. capillaris grassland as a simple method for control of Taraxacum abundance, particularly in situations of extensification or abandonment.     

Influence of cutting regime and fertilizer application on the botanical composition,yield and nutritive value of herbage of wet grasslands in Central Europe

The changes in dry matter (DM) yield, botanical composition and nutritive value of herbage to ruminants of two wet grasslands, Arrhenatherum elatius grassland (Experiment 1) and a Molinia caerulea fen meadow (Experiment 2), in which a range of cutting and fertilizer treatments were imposed in 1999, were assessed after 4–7 years of treatment imposition. Both experiments had a split‐plot design with four replicates. In Experiment 1 the three main‐plot cutting treatments were two cuts with a delayed first cut, three cuts and four cuts during the growing season of each year. In Experiment 2 the cutting treatments were two cuts with a traditional harvest time, two cuts with a delayed first cut and three cuts. The four sub‐plot fertilizer treatments were an unfertilized control, application of a phosphorus and potassium (PK) fertilizer, application of a nitrogen (N) and PK fertilizer to the first cut only (N₁PK) and application of PK plus N applied to each of two, three or four cuts (N_c PK). Application of fertilizer influenced yield and botanical composition of herbage more than the cutting treatments while the opposite occurred for nutritive value of the herbage. Application of fertilizer increased the proportion of tall grasses in Experiment 1 and forbs in Experiment 2. The proportion of Equisetum palustre, present only in Experiment 1, was reduced from 0·33 to less than 0·01 by increased cutting frequency together with the NPK fertilizer treatments. In Experiment 1 diversity of vascular plants was negatively affected only by the four‐cuts treatment while on both wet grasslands other cutting and fertilizer application treatments had no effect. Changes in DM yield of herbage caused by the cutting and fertilizer application treatments were similar for both vegetation types with DM yield increased significantly by fertilizer application but only slightly or not reduced by increasing the cutting frequency. Nutritive value of herbage was positively correlated with cutting frequency and was most influenced at the first cut.     

玉米田养鹅系统物种多样性指数与杂草生物量关系研究

试验对农牧一体化方式下玉米田养鹅模式和传统种植模式的田间杂草群落进行对比研究,统计分析放牧前各杂草的生物多样性指数和地上生物量,初步探讨玉米田养鹅模式下物种多样性指数与杂草生物量之间关系。研究结果表明,萝北、林芝两地Shannon-Wiener多样性指数、Simpson优势度指数和Margalef物种丰富度指数与地上生物量指标之间均显著相关(P0.05),说明玉米田养鹅系统群落物种多样性与生产力之间紧密相关,物种多样性的增加可明显提高地上生物量。萝北玉米田养鹅处理玉米产量较对照降低17.73%,处理间差异不显著(P0.05);林芝玉米田养鹅处理下玉米产量较对照降低40.64%,处理间差异显著(P0.05)。     

Changes in macro‐ and micronutrient contents of grasses and forbs following Miscanthus x giganteus feedstock,hydrochar and biochar application to temperate grassland

Biochar and hydrochar application to soil holds promise for climate change mitigation. This study provides first insights into the nutrient concentration and removal of grassland vegetation after addition of various carbon compounds together with pig slurry. Four treatments: control (no carbon application), feedstock, hydrochar and biochar from Miscanthus x giganteus were applied at a permanent grassland site near Giessen, Germany. Changes in plant functional groups, biomass production and nutrition status were monitored over 2 years. Total biomass production was not affected by the carbon amendments. However, biochar favoured growth of forbs over grasses, while legume growth was increased by all carbon amendments. The initial nutrient concentrations of the carbon compounds were enriched according to their degree of carbonization, potentially providing nutrients to plants. The plant biomass from hydro‐ and biochar amended plots, added up over 2 years, exhibited higher potassium concentrations compared to biomass from feedstock and control plots. All carbon amendments led to lower sodium concentrations in total biomass, compared to the control. Uncarbonized feedstock led to increased manganese concentrations in total biomass, while the concentrations of all other heavy metals were not influenced by any carbon amendment, compared to the control. From a plant and animal nutritional point of view, none of the carbon amendments reduced grassland yield or fodder quality. The study suggests that hydrochar and, even more so, biochar may provide a source of potassium to plants.     

Biomass from landscape management of grassland used for biogas production: effects of harvest date and silage additives on feedstock quality and methane yield

Biogas production from grassland biomass harvested during landscape management may help to maintain species‐rich grassland biotopes, but extensive management and late harvests often result in low‐quality biomass. Biogas production from the vegetation of Alopecuretum pratensis, Molinietum caeruleae and Caricetum gracilis, three typical grassland biotopes in north German nature reserves, was investigated in relation to harvest date. In addition, the A. pratensis vegetation was investigated for ensiling and the application of bacterial silage additives. Results indicate that biogas production might be a reasonable utilization pathway for grassland biomass from landscape management if the first cut occurs up to late summer. Methane yields of grassland biomass decreased substantially with later harvest, from up to 309 l_N kg^?1 organic dry matter (ODM) in May to below 60 l_N kg^?1 ODM in February, in correlation with increasing crude fibre contents. Caricetum gracilis vegetation was the least suitable feedstock for biogas production. It showed a rapid decline in methane yields with later harvest and 25% lower methane yields compared with other types of grassland vegetation. Application of silage additives is recommended for adequate preservation of grassland biomass from landscape management by ensiling. Addition of homofermentative lactic acid bacteria improved acidification during ensiling if sufficient fermentable sugar was available. The use of inoculant and molasses enhanced methane yields by 3–55%. Additional carbohydrate source is necessary to ensure proper ensilage when grasses are harvested after late autumn.     

Effect of low‐dose N application and early mowing on plant species composition of mesophilous meadow grassland (Arrhenatherion) in Central Europe

Semi‐natural temperate grasslands in Europe make an important contribution to biodiversity, but their existence has been endangered by both agricultural intensification and abandonment. In the Czech Republic, Arrhenatherion meadows are a typical example, with their conservation made difficult by the scarcity of research on effective management practices. We examined effects of two potentially useful approaches, application of 56 kg N ha^?1 and earlier first mowing (i.e. in the middle of May, about 2 weeks earlier than usual), on species composition of an Arrhenatherion grassland in central Bohemia over a 7‐year period (1998–2004). These treatments did not influence species richness, but resulted in small changes in canopy structure in terms of cover of individual species and particular plant functional groups. N application resulted in increases in nitrophilous species and tall graminoids, especially Alopecurus pratensis, Festuca pratensis, Heracleum sphondylium and Ranunculus acris, and in decreases in short graminoids. Earlier mowing decreased tall herbs, especially H. sphondylium, and might thus be useful in compensating for increases in some nitrophilous species owing to N application. However, earlier mowing had negative impacts on spring‐flowering species in terms of reduced cover.     

Cutting frequency vs. N application: effect of a 20‐year management in Lolio‐Cynosuretum grassland

The aim of this study was to determine the effects of different long‐term management options on re‐establishment of traditional species‐rich grassland in a Lolio‐Cynosuretum grassland. The experiment was set up in 1987 in a low‐fertilized mown pasture in the Eifel Mountains (Germany). Two and four cuts per year each with three levels of nitrogen fertilizer application were compared to no application of P and K fertilizer. Biomass production increased as a result of N application, whereas crude protein content and digestibility of organic matter improved in the four‐cut treatments. During a 20‐year period, we found a significant shift in dominant grass species without any significant effect on species richness. Lolium perenne and Elytrigia repens were replaced by Holcus lanatus and Alopecurus pratensis, especially in the two‐cut treatments with N application. In the unfertilized plots, several individuals of Platanthera bifolia appeared when swards were cut only twice per year, probably as a result of nutrient depletion together with low cutting frequency. An increase in number of cuts mainly supported plant species well adapted to intensive management, even under low N application and relatively low plant‐available P content in the soil. Therefore, we conclude that cutting frequency was a key driver on plant species composition in this experiment. The re‐establishment of traditional species‐rich grassland from intensively managed Lolio‐Cynosuretum was not achieved within 20 years of cutting management combined with absence of P and K application.     

The conservation management of mesotrophic (meadow) grassland in Northern England. 2. Effects of grazing, cutting date, fertilizer and seed application on the vegetation of an agriculturally improved sward

The plant species number and composition, iind yield of herbage biomass of an agriculturally improved hay meadow were assessed after 4 years under various combinations of grazing, fertilizer applicution. cutting date and seed addition treatments in a replicated split-plot design. Grazing treatments consisted of either autumn grazing with cattle and sheep, spring grazing with sheep or both regimes. Fertilizer application treatments consisted of either 25 kg ha^?1 N plus 12–5 kg ha^?1 P and K or no fertilizer. Cutting date treatments consisted of cuts on either 14 June, 2i July or 1 September. Seed addition treatments consisted of either no addition or sowing with a range of meadow species in the autumn. Data analysis was by correspondence analysis and analysis of variance. Species number decreased with fenilizer use and when the cutting date was 1 September. A range of species was affected by the main treatments and there were some first-order interactions, mainly between cutting date and fertilizer application. Rhinanthus minor was particularly favoured by the seed addition treatment. Species attnbutes in the regenerative and established phase were related to treatments and their effect on species composition. The National Vegetation Classification communities were associated with particular treatment regimes. The 21 July cutting date favoured ‘improved’ over ‘unimproved-traditional’ swards, with spring grazing favouring ‘unimproved-traditional’ swards. Lowest yields of herbage biomass were associated with autumn and spring grazing, the 14 June cutting date and no fenilizer treatments. The fenil-izer, 1 September cutting date and auiumn grazing treatments gave the highest yields. The implications of these results are discussed in terms of the conservation management required to return agriculturally improved mesotrophic grassland to a species composition similarto that of traditionally managed grassland.     

不同肥力和密度下玉米田杂草群落的研究

应用群落生态学方法,对玉米田杂草群落进行调查研究,探讨不同肥力和密度下玉米田杂草的群落组成、多样性和稳定性。结果表明,玉米田优势种杂草为稗草、红蓼、反枝苋、圆叶藜,其中稗草综合优势度最高。施肥可增加杂草数量和生物量,肥力和密度分别对群落中不同物种的综合优势度产生不同影响,并对玉米田杂草群落的组成、多样性和稳定性产生影响。     

Effects of systemic fungal endophytes on the performance of meadow fescue and tall fescue in mixtures with red clover

A symbiosis between grasses and systemic fungal endophytes exists in both natural and agricultural grassland communities. Our objective was to examine the effects of systemic endophytes on the competitive ability of two agronomically important grass species: meadow fescue [Festuca pratensis (Huds.) syn. Schedonorus pratensis (Huds.) P. Beauv] and tall fescue [Festuca arundinacea (Schreb.) syn. Schedonorus phoenix (Scop.)]. Plants of meadow and tall fescue were grown for 48 days in replacement series of interspecific mixture with a legume (red clover, Trifolium pratense L.) in different nutrient environments in a greenhouse. Neither of the grass species gained endophyte‐promoted competitive advantage over red clover in grass–clover mixtures. Endophyte infection increased the growth of meadow fescue monocultures by 89% compared to endophyte‐free monocultures in high‐nutrient soils, but plant competition or the cost of endophyte infection to the meadow fescue decreased the yield in resource‐limited conditions. On average, endophyte‐infected and endophyte‐free meadow fescues produced 0·15 and 0·17 g, and 0·14 and 0·14 g dry biomass per plant in mixtures with red clover in high‐ and low‐nutrient soils respectively. In contrast to meadow fescue, endophyte‐promoted growth of tall fescue monocultures was not detected. Endophyte‐infected and endophyte‐free tall fescue monocultures produced 0·76 and 0·95 g biomass per pot, respectively, in the high‐nutrient environment. Endophyte infection can increase the performance of the host grass, but the positive effects depend on the host species, the species composition and soil nutrient availability.     

Grassland responses to grazing disturbance: plant diversity changes with grazing intensity in a desert steppe

This study quantifies the impact of four different grazing regimes (heavy, moderate, light and ungrazed) on the vegetation dynamics of rangeland ecosystems along the southern boundary area of the Mu Us Desert, China. As the grazing intensities decreased, the soil quality, canopy cover, height, density, above‐ and below‐ground biomass, litter, root/shoot ratio and native plant (Aneurolepidium dasystachys) and grass abundances significantly increased; the above‐ground biomass of grasses increased, but the above‐ground biomass of forbs decreased. Ungrazed grassland has significantly improved from grasslands experiencing three other levels of grazing pressure, especially in the grassland biomass. Species richness increased as the grazing intensity decreased in the grazing grasslands, but peak species richness appeared under moderate and light grazing against lower productivity. Grazing exclusion causes desirable transitions in plant communities of desert steppe rangelands. Therefore, appropriate and efficient grazing exclusion is an available way to counteract local grassland degradation and promote rangeland sustainability.     

Biomass production of upland vegetation types in England and Wales

Abstract The objective of the study was to describe the annual and seasonal production of live biomass of six plant species or communities of the uplands of the UK –Calluna vulgaris, Vaccinium myrtillus, Nardus stricta, Molinia caerulea, Eriophorum vaginatum and Agrostis–Festuca grassland. The species or communities are important for the management of the uplands to meet both biodiversity and agriculture objectives. The annual and seasonal production of live biomass was determined for sites within six regions of England and Wales in 1995, 1996 and 1997. The six regions were North‐east England, North‐west England, North Pennines, South Pennines, South‐west England and Wales. In each region, the Institute of Terrestrial Ecology's Land Classification Scheme was used to select three or four 2 km × 2 km squares that contained a mosaic of C. vulgaris and upland grassland plant species. Uniform plots of 1 ha were selected from each 2 km × 2 km square, within which three measurements were made on each sampling occasion. Biomass of each species or community was measured within 1·0 × 0·5‐m quadrats using the same standard procedures. Measurements of annual production of current season's shoots of the pioneer, building, mature and degenerate phases of C. vulgaris and of V. myrtillus were made in October, and of the annual production of live biomass of N. stricta, M. caerulea and E. vaginatum in August. A simulated grazing regime was imposed for the Agrostis–Festuca grassland with cuts being made to a height of 4 cm at 8‐week intervals. The annual production of live biomass produced was estimated as the sum of four harvests taken during the growing season. Seasonal measurements of the amount of live biomass of all the species were also made in April, June, August and October. For C. vulgaris, there were significant (P = 0·05) differences between the pioneer, building, mature and degenerate phases in the annual production of current season's shoots, with greater amounts being produced by the phases of greater age and with higher biomass. There were significant year (P < 0·05) and region (P < 0·05) effects, with the lowest production in 1995 and in the South‐west of England. The values were higher than those observed in previous studies in Scotland, and these were interpreted as being associated with a longer growing season rather than higher summer temperatures. There was no difference between years and regions in the annual production of V. myrtillus. For the grass species, there were small differences in annual production of live biomass between years and regions. However, the annual production of live biomass of N. stricta was significantly (P < 0·01) lower in 1995 than in 1996 and 1997 and significantly (P < 0·001) lower in the South Pennines region than elsewhere. The effect of a range of weather and other environmental variables on the annual production of live biomass of each species of grass was explored, but they provided only a limited insight into the reasons for the observed differences and were found to be of limited value as predictors.     

The conservation management of upland hay meadows in Britain: a review

Upland hay meadows conforming to MG3 in the National Vegetation Classification of the UK are a rare habitat in Britain and are largely confined to upland valleys in northern England. Agricultural intensification, particularly ploughing and reseeding and a shift from hay‐making to silage production over the last 50 years, has resulted in large losses of species‐rich upland hay meadows. Remaining species‐rich meadows have been the focus of much nature conservation effort resulting in many of the species‐rich sites being protected by statutory designations or through voluntary agri‐environment scheme agreements. Research and monitoring has tended to confirm that species richness is maximized by management involving spring and autumn grazing, a mid‐July hay cut, no inorganic fertilizer and possibly low levels of farmyard manure. Deviations from this regime result in a loss of species richness. Restoration of semi‐improved grassland to swards resembling species‐rich MG3 also requires a similar regime but is also dependent on the introduction of seed of appropriate species. The role of Rhinanthus minor as a tool for manipulating meadow biodiversity during restoration management is discussed. Suggestions for future research are outlined.     

Reintroduction of grazing management after deforestation of formerly abandoned grassland and its effect on early vegetation changes in the Western Carpathians (Slovakia)

Although the process of reforestation of grassland has been widely studied in Europe, little is known about the effect of deforestation on grassland development. Thus, the specific objective of this study was to evaluate early changes in plant species composition, functional group, yield and biomass quality after deforestation of long‐term abandoned pastures. The experiment was established immediately after deforestation on sparse herbaceous vegetation (mean initial cover 27%) with the following treatments: grazing management only (G0), cutting and grazing aftermath (CG), grazing after seeding of grassland mixture (GS), grazing after a burning treatment in which branches were burned after deforestation (GB) and unmanaged control (U). Very rapid recovery of bare ground by germination and/or sprouting of grassland species was similar under all types of grazing management. Total plant species richness increased in all managed treatments except GB. Similarities according to redundancy analyses in plant species composition were found among G0, CG and GB treatments, especially for forbs with correlated rosette or creeping growth. The woody species, tall grasses and tall forbs had higher abundance in the U treatment. The restoration of grassland following deforestation of formerly reforested grassland area by grazing management was a relatively fast process, and swards were created after 3 years. The highest biomass yield was observed under treatments GS and GB. Forage quality of all managed treatments was sufficient for the demands of beef cattle grazing. However, for subsequent grassland preservation, some type of grazing management is necessary to prevent reforestation, which can occur immediately after deforestation in unmanaged places.     

The conservation management of mesotrophic (meadow) grassland in northern England. 1. Effects of grazing, cutting date and fertilizer on the vegetation of a traditionally managed sward

The results are reported from an experiment on the effects of cutting date (14 June, 21 July and I September), fertilizer application (none or 80 kg ha^?1 N plus 40 kg ha^?1 P and K) and grazing treatments (none, autumn or autumn plus spring) on the vegetation of an upland mesotrophic grassland in Upper Teesdale. northern England, UK. Effects on plant species number and cover are reported for 4 years (1989–93) of treatment. Effects on ‘species -attributes’ are given for the fourth year. The cessation of grazing combined with the use of fertilizer progressively reduced species number by about 25%. Under traditional management (no fertilizer, cutting date on 21 July, autumn and spring grazing) the species number and cover remained relatively static over the 4 years. Comparison between treatments in the fourth year showed a reduction in species number under the fertilizer application, cutting date on 1 September and no-grazing treatments. Fertilizer use together with cutting date on 1 September particularly lowered species number and cover. Analysis of variance was used to assess the effect of treatment on species that occurred frequently in the sward. A cutting date of 1 September favoured Agrostis capillaris. Alopecurus pratensis, Poa trivialis, Phleum pratense and Trisetum flavescens, The absence of grazing favoured Dactylis glomerata and Holcus lanatus. The use of fertilizer particularly favoured A. pratensis and H. lanatus. Ordination methods were used to assess the effect of treatment on the less frequent species. These were primarily associated with the treatment combination that matched ‘traditional’ management. Deviations from this ‘traditional’ regime acted separately, rather than in combination, and favoured different grass species. Traditional management was associated with ruderal, stress-tolerant ruderal and competitive ruderal strategists and with longer seed germination times, heavier seeds, some of which needed scarifying or chilling to break dormancy, and transient seed banks that germinated in the autumn. The original sward was an Anthoxanthum odora-turn-Geranium sylvatirum grassland, Briza media subcommunity (MG3b). After 4 years, Festuca ovina-Agrostis capillaris-Galium saxatile grassland, Holcus lanatus-Trifolium repens subcom-munity (U4b) and Lolium perenne-Alopecurus pratensis-Festuca pratensis grassland (MG7c) were found in many of the fertilized and late-cutting treatments.     

Effect of different grazing management systems on the herbage mass and pasture height of a Nardus stricta grassland in western Scotland, United Kingdom

The aims of this study were to examine the effect of three grazing treatments (year‐round stocking rates of 0·8 ewes ha^?1, 0·5 ewes ha^?1 and 0·5 ewes ha^?1 plus grazing cattle in summer), imposed for 4 years, on the herbage mass and surface height of a Nardus stricta‐dominated grassland in western Scotland and to obtain estimates of annual productivity of this grassland. Nardus stricta‐dominated grassland comprised proportionately 0·20 of the grazing area. Stocking rate of sheep had no significant effect on the herbage mass of the grassland in the first 2 years of the experiment, although mean summer pasture heights were significantly higher under the lower stocking rate of sheep. The pasture on the treatment with cattle grazing in summer had a significantly lower herbage mass and lower surface height than the two sheep‐only grazing treatments. Year‐to‐year variation in the herbage mass and surface height of herbage in summer was greater than the effect of treatments. Despite changes in surface height, the structural diversity of the grasslands was not increased by the treatments. The annual production of vascular plant material ranged from 417 g DM m^?2 in 1994 to 628 g DM m^?2 in 1996.     

The reclamation of bracken-dominated pastures in Bulgaria using asulam and fertilizers

Bracken ( Pteridium aquilinum ) is a major weed of considerable economic concern in upland pastures in Bulgaria and elsewhere in Europe. Between 1993 and 1998, a field experiment was carried out to test methods for restoring productive meadows. Initially, spraying asulam (4·8 kg a.i. ha⁻¹) was used to control the bracken on the site; this was achieved in terms of reduced frond densities and a higher level of grassland establishment. This grassland was dominated by Vicia cassubica and the perennial grasses Agrostis vulgaris , Dactylis glomerata , Festuca rubra , Holcus lanatus and Poa pratensis .
After 2 years, a fertilizer addition experiment was started with four treatments (no fertilizer; addition of phosphorus; addition of nitrogen and phosphorus; addition of nitrogen, phosphorus and potassium. The phosphorus and potassium fertilizers were applied annually in the early spring at 80 kg of P  ha⁻¹ year⁻¹ and 50 kg of K ha⁻¹ year⁻¹, and nitrogen was added at the start of grass growth at 60 kg of N ha⁻¹ year⁻¹. At the same time, a twice-yearly hay-cutting regime was implemented. Fertilizer addition increased both the quantity and the quality of the resulting grassland. The herbage dry matter was increased by at least a factor of two depending on fertilizer combination, and there was an increase in grass and legume cover and a decrease in both weed cover and bracken recovery. However, although bracken recovery was inversely related to grassland production, there was a consistent increase in bracken density across all treatments between 1997 and 1998, suggesting that increasing herbage biomass merely delays bracken recovery. The implications of these findings are discussed.     

Economic comparison of forage production from annual crops, perennial pasture and native grassland in the alpine region of the Qinghai-Tibetan Plateau, China

Economic costs and benefits for different grassland production systems were analysed. Comparisons included one native grassland (alpine meadow dominated by sedges) system, four perennial monocultures of smooth bromegrass (Bromus inermis Leyss, SB), Siberian wild ryegrass (Elymus sibricus Linn., SW), drooping wild ryegrass (Elymus nutans Griseb, DW) and crested wheatgrass (Agropyron cristatum Gaertn., CW), three mixtures of these grasses (SB + DW, SB + SW + CW and SB + SW + DW + CW), and two annual monocultures of forage oats (FO) and annual ryegrass (Lolium annual, AR) in the alpine grasslands of Qinghai‐Tibet, China. Perennial grass monocultures of SW and DW and perennial grass mixtures of SB + SW + DW + CW and SB + SW + CW had higher forage yields, total revenues, output:input ratios and net profits than native grassland. These grasses and mixtures can be used to reseed native grassland and improve degraded grassland in the alpine region of the Qinghai‐Tibetan Plateau. Perennial grass mixtures can replace FO for more sustainable agricultural production systems as they are comparable in economic value and superior in ecological value to FO.