Hay production from lowland semi-natural grasslands: a review of implications for ruminant livestock systems

Data on total, seasonal and between-year variability in the productivity and nutritional quality of cut forages obtained from a range of lowland semi-natural grasslands are reviewed. Dry-matter production, as hay, from unfertilized species-rich semi-natural grasslands ranged from less than 20% to about 80% of the production that might be expected from agriculturally improved and intensively managed grasslands. Unfertilized species-rich grasslands had lower growth rates, reflecting low nutrient availability in spring and early summer. Low soil phosphorus availability appears to be a key factor allowing high species-richness to be maintained. The in vitro digestibilities of herbage cut for hay from semi-natural grasslands were 20%, or more, below values for conserved forages from intensively managed grassland. When losses incurred during the hay-making process were taken into account, then the nitrogen content of hays from many semi-natural grasslands appear to be sub-optimal for productive livestock. Metabolizable energy values of herbage cut for hay were 10–40% below values for intensively managed conserved grass. Phosphorus content of forages from most species-rich grasslands was either below the metabolic requirement of livestock or inadequate to sustain high individual animal performance. Potential problems associated with supplementation of the diet with phosphorus, and with high calcium-to-phosphorus ratios, are discussed. Although potassium content of most of the herbage cut for hay was adequate for productive ruminant livestock, exceptions arise with hay cut after July. The magnesium content of cut herbage from some semi-natural grasslands was below an adequate level for productive livestock. Most cut herbage appeared to contain adequate amounts of sodium. Inadequacy of the mineral content of hays from semi-natural grasslands for ruminant livestock will be exacerbated by nutrient losses incurred during the hay-making process and particularly so when hay- making is prolonged by wet weather. Few feeding studies using hays from semi-natural grasslands of high nature conservation interest have been conducted. Lack of such data makes it difficult to plan any integrated use of these hays in ruminant feed budgets for livestock systems.     

Spatial and structural uniformity of lowland agricultural grassland in England: a context for low biodiversity

The contention that agricultural grassland within the UK is spatially and structurally uniform across wide differences in livestock farming intensity is examined. Total nitrogen (N) input was used as a surrogate for management intensity. Farms with average annual N inputs of >200 kg ha^?1 were categorized as highly intensive, those with N inputs of 50–200 kg N ha^?1 as moderately intensive and those with inputs of <50 kg N ha^?1 were categorized as extensive. Four farms within each management category were selected in two discrete regions: one in south‐west England, typifying a landscape dominated by agricultural grassland, the other in south‐east England with a more mixed‐farming landscape. Specific N input and management data, and sward botanical composition and structure, were obtained on four fields per farm. The south‐west region had a higher proportion of farms with dairy cattle than in the south‐east England region. The average N input and stocking rates were higher within the intensive‐management category farms in south‐west England than in south‐east England. Old permanent grasslands contained variable amounts of sown species, such as Lolium perenne, and were dominated by a few (generally <5) non‐sown grass species. Grassland that received >75 kg N ha ^?1 year^?1 contained <7 plant species and <3 forb species m^?2. Grassland communities with >12 plant species and >5 forb species m^?2 were only found in study fields that received <50 kg N ha^?1 year^?1. Grasslands with >10 forb species m^?2 were found only in sites receiving <15 kg N ha^?1. Of importance at a landscape scale was ubiquity of species‐poor and similar grassland plant communities across the management intensity range within and between livestock farms. Grassland in the extensive management category was similar in structure in terms of sward height and/or sward density to more intensively managed grasslands. This study revealed, albeit in two lowland sample regions in the UK, the ubiquity of grass‐dominated, species‐poor and structurally uniform grasslands, irrespective of apparently broad differences in farming intensity. The consequences of this spatial uniformity on grassland biodiversity are likely to be profound.     

The productivity of grassland farms in seven climatic zones of England and Wales

Records of grassland productivity were kept for 2 years on 152 dairy and 179 beef farms. Results were collated for six lowland zones, delineated primarily on the basis of average rainfall, and an upland zone. Contemporary and long-term average meteorological records were also collected.
In most of the lowland zones stocking rates and use of fertilizer N were similar, but utilized metabolizable energy (UME) output from grass varied; it was 25% higher in the wet, cool zone of north-west England and east Wales than in the dry zone of eastern England. The ranking of zones for utilized output corresponded closely with the ranking for summer rainfall.
On upland farms stocking rate was 25% lower and UME output 15% lower than on lowland farms, but this was achieved from little more than half the N input.
The differences between zones were similar to those shown in other published farm data. They also showed a similar trend to that demonstrated in grass cutting experiments. This suggests that farmers were, on average, able to exploit the extra grass grown in wetter climates. The incidence of difficult topography and impeded drainage was similar in dry and wet zones, but did have a more serious effect in the wet zones. The much higher level of concentrate feeding in the driest zone may have reduced the utilization of grass.     

Long-term sustainability of wood-pasture separation processes—A matter of seed mixtures and management

We studied the performance of different seed mixtures and the influence of liming on the establishment of a montane pasture under acidic site conditions during a wood-pasture separation process from 1998 to 2001 in Styria, Austria. Two treatments (with and without liming) were established, each with four seeding treatments (without seeding, commercial, site-adapted and site-specific mixtures), and all plots were regularly fertilized from 1998 to 2002. Vegetation surveys and forage analyses regarding development of vegetation cover, seeded species persistence, quality and yield parameters were conducted again in 2014 and 2016; soil samples were taken in 2015. After cessation of regular fertilization, the analysed soil parameters declined to levels that were sufficient or low for grasslands. pH decreased again over time, but still was significantly higher (p = .0034) in the liming treatment. The single liming during experimental set-up also caused better long-term performance for nearly all vegetation, quality and yield parameters. The site-specific seed mixture performed best regarding most analysed parameters, under both liming treatments. Concerning seeded species, the habitat-typical species Agrostis capillaris, Festuca rubra agg. and Trifolium repens persisted best with and without liming. All analysed vegetation and yield parameters stayed far behind their results of 2001 and their potential. The use of site-specific seed mixtures supports the establishment of productive grassland on specific locations. The long-term results also illustrated that even low-input management like liming in multi-annual intervals can help to improve acidic site and growing conditions significantly and thereby increases the sustainability of cost-intensive wood-pasture separation processes under similar conditions.     

Effects of ecological restoration‐induced land‐use change and improved management on grassland net primary productivity in the Shiyanghe River Basin,north‐west China

To address severe grassland degradation, the Chinese government implemented national restoration programmes, which in turn drove a research focus towards assessment of the environmental effectiveness of such initiatives. In this study, net primary productivity (NPP) was used as an indicator for assessing the impacts of land use and cover change (LUCC), improved land‐use management and climate change on the grassland ecosystem of the Shiyanghe River Basin. NPP was calculated on the basis of the Carnegie–Ames–Stanford Approach model, which is driven by a Moderate Resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index and meteorological data. The LUCC data for 2001 and 2009 were derived from MODIS land‐cover data. During the study period, the net increase in grassland development was 5105·5 km², with 80·4% of the newly developed grasslands attributed to desert‐to‐grassland conversion. The total NPP of grasslands in 2009 increased by 659·62 Gg C compared with that in 2001. The contributions of human activity and climate change to total NPP increase were 133 and ?33% respectively. Land conversion and improved management measures directly increased grassland NPP. These factors are dominant positive driving forces, whereas warm and dry climates impose adverse effects on grassland restoration in the study site.     

Infestation of improved grasslands by Juncus effusus L. in the catchment of the River Tyne,Northern England: a field survey

Soft rush, Juncus efffusus L., is a widespread weed of managed grasslands. In 1991, a sample-based field survey of the weed's distribution in improved grasslands was conducted within the catchment of the River Tyne in Northern England. The land classes of the Institute of Terrestrial Ecology (ITE) environmental landscape classification system were used as sampling strata. In total, 182 I-km grid squares were surveyed. Areas of improved grassland and levels of J. effusus infestation differed significantly between land classes, but there was also wide variation between grid squares within land classes. Most squares within a land class had no J. effusus, while a proportion had large areas. Extra-polation from the sample data suggested that an area equivalent to 24·0% of the 3000km² land surface of the catchment supported improved grassland, of which 3·5% was infested with the rush. Infestation of improved grassland was estimated to be lowest in the lowlands (2·0% of improved grassland), intermediate in the marginal uplands (3·0% of improved grassland) and greatest in the uplands (10·8% of improved grassland). Data from the Farm Business Survey, on broad patterns of utilization of improved grassland for hay, silage and livestock in lowland, marginal upland, and upland landscapes in the catchment, do not readily explain the observed variation in infestation levels, which may reflect local factors and the availability of propagules from adjacent rough grazing land.     

Livestock grazing intensity affects abundance of Common shrews (Sorex araneus) in two meadows in Denmark

Background  

Current nature conservation in semi-natural grasslands often includes grazing and hay cutting, as well as the abandonment of draining. Semi-natural grassland and in particular meadows constitute important habitat type for a large number of animal species in today's fragmented and intensively cultivated landscape of Europe. Here we focus on the population characteristics of Common shrews Sorex araneus in relation to livestock grazing intensity in two wet meadows in western Denmark.     

Seasonal dynamics of biomass production and herbage quality of three grasslands with contrasting functional compositions

Classifying grasses into plant functional types (PFT) according to their strategy of nutrient capture (PFT A, B and b) or nutrient conservation (PFT C) is claimed to predict variability in biomass production and herbage quality in grasslands. PFT A, B and b are characterized by higher production than PFT C, with higher nutritive value, which decreases rapidly. PFT C is characterized by lower nutritive value, which remains more stable in time. The aim of this study was to quantify the consequences of PFT composition at the community level on the seasonal dynamics of biomass and herbage quality for livestock feed. We studied three grasslands located in the same area with contrasting PFT composition and classified PFT A, PFT Bb and PFT C. The dynamics of vegetation stages, dry‐matter yield and nutritive value were followed over three vegetation cycles in 2007–2008. In the first cycle, biomass accumulation was high for the PFT A and PFT Bb grasslands and the high quality of herbage declined rapidly with the reproductive development. By contrast, biomass accumulation was slow in the PFT C grassland, with a lower quality that declined slowly, consistent with the later reproductive development. For regrowth cycles, the same ranking of grasslands was observed for biomass accumulation, and differences in digestibility were similar to those observed at the beginning of the first vegetation cycle. Combining type of grassland with sum of temperature for the first cycle and regrowth days for the second and third vegetation cycles provided quantitative models of herbage biomass and quality.     

Are soil‐adjusted vegetation indices better than soil‐unadjusted vegetation indices for above‐ground green biomass estimation in arid and semi‐arid grasslands?

Accurate estimation of grassland biomass has been a central focus due to its importance in ecosystem processes and carbon cycles. This study aimed to examine whether the performance of soil‐adjusted vegetation indices for estimating above‐ground green biomass was better than that of soil‐unadjusted vegetation indices in arid and semi‐arid grasslands. Above‐ground green biomass in desert steppe of Inner Mongolia and corresponding moderate‐resolution imaging spectroradiometer (MODIS) surface reflectance 8‐day composite MOD09Q1 data were collected during late September of 2013. Results showed that soil‐adjusted SAVI (soil‐adjusted vegetation index), MSAVI (modified soil‐adjusted vegetation index), OSAVI (optimized soil‐adjusted vegetation index), TSAVI (transformed soil‐adjusted vegetation index), ATSAVI (adjusted transformed soil‐adjusted vegetation index) and PVI (perpendicular vegetation index) did not improve estimation accuracy over soil‐unadjusted simple ratio (SR) and normalized difference vegetation index (NDVI), due to low green vegetation cover (<30%) in the study area. Our results suggest that these soil‐adjusted vegetation indices may be not suitable for describing green vegetation information in arid and semi‐arid grasslands with low green vegetation cover (<30%).     

干热河谷区灌草草地的水土保持效应

为了恢复干热河谷退化山区草地的生态环境,提高草地的水土保持能力,于2004～2007年在金沙江干热河谷区的云南省永胜县设置样点,在退化严重的草地上建植了7个组合模式的灌草复合型草地,以凋落物量、最大持水量、有效截流量、草地盖度、草地土壤崩解时间为指标,对建植3年的灌草草地的水保效果进行研究。结果表明,＂灌＋草＋藤＂最适宜金沙江干热河谷区的植被重建,其中＂木豆＋非洲狗尾草＋高羊茅＋大翼豆＂建植模式显著地提高草地植被盖度和凋落物重量。凋落物的持水能力与凋落物重量呈显著的正相关;土壤根量与土体崩塌时间呈显著的正相关。灌草草地植被盖度、凋落物量和根系重量的显著提高,有效地提高草地的持水量和有效截流量,推迟草地土壤崩解时间,增加了土体的稳定性,对防止水土流失和泥石流的形成具有重要作用。     

Impacts of elevated atmospheric CO2 and temperature on plant community structure of a temperate grassland are modulated by cutting frequency

To determine the impacts of climate change and defoliation on the community structure and plant diversity of a semi‐natural temperate grassland, monoliths of a permanent grassland were exposed to ambient or elevated atmospheric CO₂ concentrations (ambient + 235 ppmv) and temperature (ambient + 3°C) from October 1998 to December 2000. The monoliths were subjected to two different cutting frequencies, either two or six cuts per year. The grassland community structure changed during the course of the experiment and was more responsive to changes in management than to changes in climate. Increased cutting frequency stimulated plant diversity by enhancing the number of forb species, but plant diversity was not significantly affected by climate change. The contribution of individual plant species to the vegetation cover revealed species‐specific responses to climate change and cutting frequency, but for most species significant interactions between climate change and cutting frequency were present. There were no clear‐cut effects of treatments on the total annual yield and the proportion of forbs present, as significant interactions between climate change and cutting frequency occurred. It is concluded that differential grassland management will modify plant species‐specific responses to climate change and resulting changes in the botanical composition of mixed‐species, temperate grasslands.     

The effects of pesticide application on upland permanent pasture

An estimate of the level of pest damage on enclosed upland permanent pasture in England and Wales was made by reducing invertebrate populations with insecticides at thirteen well-distributed sites and measuring the effect on herbage growth over a 3-year period. Potential pests were fewer in number than on lowland pastures and there was a wide range in herbage yield between sites. Insecticide treatment significantly increased annual yields at only three of the sites, and significantly decreased yield at two of the sites. Insect damage to grassland appears to be much less important in upland than in lowland areas: this may be due to the relative scarcity of frit-fly in these areas, but this could change if its preferred host, ryegrass, were encouraged by intensification of sward management in the uplands. At all but one of the sites insecticide treatment led to considerable soil compaction, probably as a consequence of suppressing earthworm populations.     

POTENTIAL PASTURE PRODUCTION IN THE UPLANDS OF WALES

A comprehensive study of the climatic, soil and vegetation restraints on grassland production in the hill areas of Britain is an essential preliminary stage in land use planning for those areas. Climatic data, recorded continuously at four centres in mid-Wales, emphasize the extent of altitudinal, topographic, seasonal and diurnal variation in zones with improvement potential. Annual solar energy income is negatively correlated with rainfall and cloud cover. Under wet conditions in the western hills, mean daily solar radiation during 1966–69 decreased by 15% between two centres at 30 and 305 m (103 and 1100 ft) 0.D. from 9.92 MJ/m² to 7–07 MJ/m²= (204 to 169 cal/cm²). Radiation receipts in the drier eastern uplands at 305 m (1000 ft) were as high between May and August as in the western lowlands, but winter temperatures were considerably lower. Comparisons are made with conditions in other upland areas of Britain.     

Measurement of above-ground plant biomass, forage availability and grazing impact by combining satellite image processing and field survey in a dry area of north-eastern Syria

Field survey and satellite image processing methods were used to estimate the total available forage over an area of 95 034 ha in north‐eastern Syria, and to assess grazing impact on the area. The above‐ground plant biomass was measured by a quadrat method at three sites in each of eight vegetation classes. Available forage was measured by excluding woody parts of shrubs from the whole aerial plant parts. The total above‐ground plant biomass and available forage were estimated by extrapolating the measured point data to the whole target area using classified vegetation data by satellite image processing. Grazing impact was assessed by calculating the differences between the total available forage at the end of growing season and the end of dry season. The values for the estimated total available forage (s.e. of mean) in the area were 55 628 000 (12 920 000) kg DM and 30 007 000 (2 437 000) kg DM at the end of growing season and dry season respectively. Although the area of the cereal fields covered only 0·315 of the area, about 0·69 and 0·82 of the available forage existed in the harvested cereal fields at the ends of growing season and dry season respectively. The integration of cereal fields and rangeland is a normal land use system for livestock management in the area. The higher cover of herbaceous vegetation types showed higher grazing impacts which reduced the total available forage at the end of the growing season by 0·817 (0·199) at the end of the dry season. Although these dense herbaceous vegetation types could possibly produce more available forage, they would incur more intensive grazing impact. On the contrary, lighter grazing impact would occur with a higher cover of shrub vegetation types. The importance of maintaining plant cover over the rangeland area to protect the land against soil erosion is stressed.     

FERTILIZER USE ON GRASSLAND IN ENGLAND AND WALES

The paper describes the use of fertilizers on grassland in England and Wales, as shown by surveys of fertilizer practice carried out during 1957–60.
About a third of the total consumption of N and K and almost half the total consumption of P is on grassland. Fertilizer use on leys has increased rapidly in recent years and the overall average rate of application is now of the order of 0·3 cwt N, P₂O₅ and K₂O per acre per annum; permanent grass receives about half as much P and very much less N and K than the leys.
Generally speaking, consumption of N and K per acre of grassland was higher in arable districts than in livestock-farming areas, and on dairy farms than on rearing and feeding farms. However, rearing and feeding farms received more P per acre of grass (in particular, more basic slag) than arable farms. Little farmyard manure was used on grassland in the arable districts, whereas in the dairy counties of the western half of England and in Wales it formed a substantial part of the total plant nutrients supplied to grassland, particularly on fields mown for hay.
The paper also gives information on types of fertilizers used and the timing of fertilizer applications to grassland. All but about a fifth of the nitrogen used on grassland was applied between February and April.     

Effects of livestock breed and grazing intensity on biodiversity and production in grazing systems. 2. Diet selection

Reduction in grazing intensity and the use of traditional instead of commercial breeds have frequently been recommended to meet biodiversity and production goals in sustainable grazing systems. The impact of such practices within a range of contrasting grassland vegetation types was studied. This paper describes the effects on foraging behaviour in a study conducted over three years on mesotrophic or semi-natural grasslands in UK (steers), Germany (steers), France (heifers) and Italy (sheep). Three treatments were performed: (i) a moderate grazing intensity using a commercial breed, (ii) a more lenient grazing intensity with a commercial breed and (iii) a more lenient intensity with a traditional breed. Livestock at all sites preferentially selected bites containing legumes and forbs, and also short rather than tall vegetative patches. Grazing intensity affected not only diet consumed, largely reflecting the different availabilities of dietary components, but also some differences in diet selection. Livestock grazing the more productive mesotrophic grasslands more frequently exploited short patches of higher nutritive value, which is expected to reinforce the spatial heterogeneity of the pastures. Studies in the UK and Germany also revealed that steers showed a more pronounced selection for short patches at the lenient grazing intensity. More homogeneous grazing by livestock on the semi-natural grasslands with fine-scale heterogeneity is likely to decrease their spatial heterogeneity. There were few differences in the choices made by commercial and traditional breed livestock. North Devon steers in the UK expressed a greater selection for tall grass-forb bites than Charolais × Holstein crossbreds, whereas traditional breeds appeared slightly less selective than commercial breeds at the other three sites.     

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.     

Effects of shrub encroachment on herbage production and nutritive value in semi-arid Mediterranean grasslands

There is limited information on the effects of the increase in the density of shrubs on herbage production and nutritive value of natural grasslands in the Mediterranean region, currently facing major land use changes. Herbage production of drymatter (herbaceous fractions, of plant functional groups and by species), crude protein (CP), neutral‐detergent fibre (NDF), acid‐detergent fibre (ADF), acid‐detergent lignin (ADL) and hemicellulose concentrations and in vitro organic matter digestibility were determined at the time of peak of annual growth across four types of grassland vegetation each characterized by different shrub cover regimes. A sharp reduction in herbage production and a reduction in nutritive value were found as a result of the increase in shrub cover. These changes appeared to be closely related to the shift in plant functional groups detected as shrub density increased. Herbage production from grasses and legumes was found to be more sensitive to shrub cover changes than herbage production from forbs, whereas, as grassland types became denser, annual species were gradually replaced by perennials and C₄ grasses by C₃ ones. The impact of shrub encroachment on Mediterranean grasslands is discussed in relation to their use by livestock.     

Reproductive responses of alpine plants to grassland degradation and artificial restoration in the Qinghai–Tibetan Plateau

Artificial grassland establishment has been implemented in the alpine region of Qinghai–Tibetan Plateau in China as a mitigation tool against grassland degradation, one of the major environmental problems in this region. We hypothesized that both grassland degradation and artificial restoration may alter the reproductive modes of the alpine vegetation at the levels of individual species as well as plant functional groups. By investigating a long-term field study of grassland degradation and artificial restoration experiments, we found that alpine plants can maintain a highly plastic relationship between sexual and asexual reproduction, that is, the alpine plants in degraded grasslands increased their efforts towards sexual reproduction while those in artificially restored grasslands promoted their efforts in vegetative reproduction with in the year after restoration. The high reproductive plasticity of the alpine plants can be regulated through a number of mechanisms, which include changing proportion of clonal species in the plant composition, altering number ratio of sexual and vegetative propagules, shifting biomass allocation for sexual and vegetative reproduction at both individual species and functional group levels. These conclusions demonstrate how crucial it is to consider manipulation of reproductive modes needed to restore the structure and stability of degraded alpine grasslands.