Effects Of Grassland Management Research Articles

Friend and foe? The effects of grassland management on global patterns of spider diversity

1. Grassland ecosystems have been used worldwide for food production through pastoral and cropping activities. In these ecosystems, spiders constitute important mesopredators, which are affected by grassland management in opposite ways. Historically, the spider taxonomic diversity has been the main focus in studies of grazing impacts in grassland ecosystems, while the intrinsic variability of traits within spiders have been neglected, which may have led to mistaken conclusions. Our objective is to reanalyse the effects of grazing on spider taxonomic and functional guilds on worldwide grasslands.2. We conducted a systematic review of the literature from the last 10 years, to assess the influence of grazing on the taxonomic and functional guild diversity of spiders worldwide. Using Generalised Linear Mixed Models, we assessed the effects of grazing pressure and type of herd on abundance, richness of spider species, and guilds.3. In the taxonomic perspective, we found no evidence of grazing impact on the abundance and richness of spiders. However, in the functional guild perspective, high grazing pressure reduced the diversity of web building spiders and enhanced diversity of ground dwelling spiders. Moreover, pastures containing more than one grazing species enhanced the diversity of ambush spiders.4. Overall, the functional guild diversity of spiders in grassland ecosystems seems to be more influenced by grazing intensity. Our results suggest that grazing intensity can change the guild composition of the araneofauna in grasslands, with guilds responding differently to grazing.

Effects of mowing and fertilization on soil quality in a semiarid grassland of North China

AbstractSoil quality has been defined as the capacity to sustain biological productivity and maintain environmental quality. Mowing and fertilization may affect ecosystem function through numerous soil properties, especially in semiarid grasslands where plant growth is limited by nutrient availability. However, the effects of grassland management on the trade‐off between soil quality and plant community structure is still unclear. Understanding the effect of land use type on soil quality is essential to adopt proper grassland management practices for a specific region. Principal component analysis was used to calculate a soil quality index (SQI) with 18 variables under the following treatments: control, mowing, nitrogen addition, and mowing plus nitrogen addition in August 2017 in a typical steppe of North China. This study showed that nitrogen addition significantly increased SQI by 0.82, field water capacity by 3.77%, soil capillary porosity by 3.30%, and soil available nitrogen content by 13.85 mg kg−1, but reduced soil aggregate proportion by 3.07%, microbial biomass nitrogen content by 7.74 mg kg−1, arbuscular mycorrhizal fungi by 0.02 μmol g−1, the ratio of fungus to bacteria by 0.16, and the ratio of Gram‐positive bacteria to Gram‐negative bacteria by 0.13 across the mowing and unmowing treatments. Nitrogen addition could improve productivity by increasing the soil quality but reduce plant diversity of the grassland ecosystems. Mowing did not affect SQI and aboveground biomass. The results suggested that fertilization as grassland management improved soil quality and productivity, whereas mowing was a sustainable way to maintain plant diversity in this semiarid grassland.

Effects of grassland management on plant nitrogen use efficiency (NUE): Evidence from a long-term experiment

Grassland management intensification can greatly influence nitrogen (N) dynamics between aboveground and belowground compartments mainly because of the large amount of available N forms, which are repeatedly added to soils. A better understanding of how chronic fertilisation might affect N use efficiency (NUE) in plants can contribute to reducing N losses from soils and improve the sustainability of managed grasslands. Here we address how NUE might be affected by (1) the addition of key nutrients (e.g. N, P, K, Mg) in different combinations, (2) grazing by rabbits, and (3) liming (i.e. CaCO3 applications) in a 22-year-old permanent grassland experiment established in Berkshire, UK, in 1991. We first calculate seven different NUE indexes, which are known to respond either to changes in soil N availability (i.e. endogenous N inputs from soil N mineralization processes) or to exogenous N inputs (i.e. synthetic N fertiliser). We found that plant NUE calculated as plant biomass produced per unit of N acquired significantly decreased under the chronic addition of multiple nutrients (NPKMg) and was even lower under N-only applications. Most NUE indexes significantly decreased under grazing but greatly increased under liming applications. We found evidence that NUE indexes, which accounted for endogenous N sources decreased at increased rates of soil N mineralization. Finally, we found no significant relationships between any of the NUE indexes and estimates of soil N losses (Mg N ha−1) or N retention in soils (i.e. units of soil N retained per unit of N added) calculated from changes in net soil N budget over 22 years. Our study carried out on relatively acidic sandy soils suggests how liming applications in combination with low levels of multi-nutrient additions (NPKMg) can significantly improve plant biomass production per unit of N added thus contributing to enhance the sustainability of managed grassland ecosystems.

Effects of grassland management on overwintering bird communities

ABSTRACTBirds that depend on grassland and successional‐scrub vegetation communities are experiencing a greater decline than any other avian assemblage in North America. Habitat loss and degradation on breeding and wintering grounds are among the leading causes of these declines. We used public and private lands in northern Virginia, USA, to explore benefits of grassland management and associated field structure on supporting overwintering bird species from 2013 to 2016. Specifically, we used non‐metric multidimensional scaling and multispecies occupancy models to compare species richness and habitat associations of grassland‐obligate and successional‐scrub species during winter in fields comprised of native warm‐season grasses (WSG) or non‐native cool‐season grasses (CSG) that were managed at different times of the year. Results demonstrated positive correlations of grassland‐obligate species with decreased vegetation structure and a higher percentage of grass cover, whereas successional‐scrub species positively correlated with increased vegetation structure and height and increased percentages of woody stems, forb cover, and bare ground. Fields of WSG supported higher estimated total and target species richness compared to fields of CSG. Estimated species richness was also influenced by management timing, with fields managed during the previous winter or left unmanaged exhibiting higher estimated richness than fields managed in summer or fall. Warm‐season grass fields managed in the previous winter or left unmanaged had higher estimated species richness than any other treatment group. This study identifies important winter habitat associations (e.g., vegetation height and field openness) with species abundance and richness and can be used to make inferences about optimal management practices for overwintering avian species in eastern grasslands of North America. © 2019 The Authors. Journal of Wildlife Management Published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.

Microbial carbon and nitrogen cycling responses to drought and temperature in differently managed mountain grasslands

Grassland management can modify soil microbial carbon (C) and nitrogen (N) cycling, affecting the resistance to extreme weather events, which are predicted to increase in frequency and magnitude in the near future. However, effects of grassland management on microbial C and N cycling and their responses to extreme weather events, such as droughts and heatwaves, have rarely been tested in a combined approach. We therefore investigated whether grassland management affects microbial C and N cycling responses to drought and temperature manipulation. We collected soils from in situ drought experiments conducted in an extensively managed and an abandoned mountain grassland and incubated them at two temperature levels. We measured microbial respiration and substrate incorporation, as well as gross rates of organic and inorganic N cycling to estimate microbial C and N use efficiencies (CUE and NUE). The managed grassland was characterized by lower microbial biomass, lower fungi to bacteria ratio, and higher microbial CUE, but only slightly different microbial NUE. At both sites drought induced a shift in microbial community composition driven by an increase in Gram-positive bacterial abundance. Drought significantly reduced C substrate respiration and incorporation by microbes at both sites, while microbial CUE remained constant. In contrast, drought increased gross rates of N mineralization at both sites, whereas gross amino acid uptake rates only marginally changed. We observed a significant direct, as well as interactive effect between land management and drought on microbial NUE. Increased temperatures significantly stimulated microbial respiration and reduced microbial CUE independent of drought or land management. Although microbial N processing rates showed no clear response, microbial NUE significantly decreased at higher temperatures. In summary in our study, microbial CUE, in particular respiration, is more responsive to temperature changes. Although N processing rates were stronger responding to drought than to temperature microbial NUE was affected by both drought and temperature increase. We conclude that direct effects of drought and heatwaves can induce different responses in soil microbial C and N cycling similarly in the studied land management systems.

Effects of grassland management on soil nutrients and their spatial distribution on the Qinghai-Tibetan Plateau, China

After grasslands were contracted to individual households on the Qinghai-Tibetan Pla-teau, two grassland management patterns were formed, i.e., the single-household management pattern (SMP) and the multi-household management pattern (MMP). The soil nutrients and their spatial distributions under those two patterns were compared in the Nagchu Prefecture of Tibet. The results showed that the soil organic carbon, total nitrogen, and total phosphorus under the MMP (84.31, 6.87 and 0.59 g·kg-1) were all significantly higher than those under the SMP (73.57, 6.07 and 0.54 g·kg-1). On the vertical dimension, the variation coefficient of soil total phosphorous between 0-15 cm layer and 15-30 cm layer under SMP had no significant difference, while that of soil pH, soil organic carbon and total nitrogen in 15-30 cm layer were all higher than 0-15 cm layer under both patterns. On the horizontal dimension, the variation coefficients of soil organic carbon and total nitrogen under SMP were significantly higher than those under MMP, with the estimated values for the former being 25.7% and 23.5%, and for the latter being 19.3% and 18.6%, respectively. Compared with the MMP, the uneven distribution of nutrients could easily lead to soil nutrient loss under the SMP.

Effects of grassland management on plant C:N:P stoichiometry: implications for soil element cycling and storage

AbstractThe functioning of human‐managed grassland ecosystems strongly depends on how common management practices (e.g., animal grazing and the chronic addition of fertilizing materials to soils) interact to influence plant and soil element stoichiometry. Here we use data from a 22‐yr‐long grassland experiment to address whether and how plant element stoichiometry (i.e., carbon [C], nitrogen [N], phosphorus [P] ratios) might respond to (1) animal grazing, (2) agricultural liming (i.e., CaCO3) applications, and (3) nutrient fertilization. We also ask whether plant C:N:P stoichiometry could predict changes in soil N and P availability and in soil C, N, and P stocks. We found that grassland management significantly affected plant C:N:P ratios as predicted by ecological stoichiometry theory. For example, plant aboveground and belowground C:N and C:P ratios decreased under chronic N and P fertilization, respectively. Plant C:N and C:P ratios were significantly greater in unfertilized (control) soils. Also plant C:N ratios were highest under P‐only additions, whereas plant C:P ratios were highest under N‐only additions. However, unpredictable changes in C:N:P ratios also occurred, suggesting that plant tissue chemistry may not be a simple reflection of soil nutrient availability. Changes in plant C:nutrient ratios well predicted variation in soil nutrient availability, but not in soil C, N, and P stocks. Contrary to expectations, soil C stocks significantly increased with decreasing plant C:N ratios in the nutrient‐fertilized grasslands and not with increasing plant C:N ratios in the unfertilized grasslands. We suggest that a better mechanistic understanding of the negative relationship between plant C:N stoichiometry and soil C accrual will greatly help in improving the sustainability of human‐managed grasslands.

The effect of grassland management on diversity and composition of ground-dwelling spider assemblages in the Mátra Landscape Protection Area of Hungary

AbstractThe main objective of this paper is to report the effect of shrub removal and mowing on the diversity and composition of ground-dwelling spider assemblages in Natura 2000 habitats of Mátra Mountains. We found significant effects of shrub removal and mowing on spider communities. Diversity decreased in the year following shrub removal but increased in the following years. Spider diversity in the final year decreased due to the lack of additional treatments. During our study the hay meadows were the most diverse habitats compared to control shrubs and treated shrubs. Treatments caused changes in community structure: the highest number of generalist species was observed in the treated shrubs, and the highest density of rare and protected species in the hay meadows. The high species turnover observed between hay meadows and control shrubs reflects the importance of grassland management. We conclude that shrub removal an effective grassland management action to increase spiders diversity in Natura 2000 habitats. Finally, treated shrubs require additional treatments such as mowing to ensure the spider communities inhabiting them are as diverse as those inhabiting meadows.

Impact of Organic Fertilisation and Subsequent Grassland Abandonment on Floristic Composition

Abstract The aim of this study was to evaluate changes in floristic composition of permanent grasslands after the cessation of their regular utilisation and organic fertilisation. A long-term small plot trial was established in 2004 in locality Rapotín. During 2004-2012, the experiment was fertilised with compost and slurry, both with the range of stocking rates 0.9, 1.4 and 2.0 livestock units (LU)/ha (corresponding to 54, 84, and 120 kg N/ha). The plots were cut 2-4 times per year depending on given dose of fertiliser. During 2013‒2016, the regular management was ceased and the grasslands were completely abandoned. Before the grassland abandonment, the highest total number of species (24 species) was found in the treatments regularly fertilised with compost. The dominance of grasses was influenced by the grassland management, with decreasing intensity of utilisation, the dominance of grasses increased. Four years after the grassland abandonment, the species diversity in almost all treatments decreased and the dominance of grasses increased in all treatments, up to the value 67-80%. Based on the data about the soil chemical parameters from two investigated years, our results suggested not only the effect of grassland management and its subsequent abandonment, but also a residual effect of the both organic fertilisers. These findings indicated the importance of the maintenance of regular grassland management for sustainable conservation of grassland communities.

Effects of grassland management on the community structure, aboveground biomass and stability of a temperate steppe in Inner Mongolia, China

Plant community structure responds strongly to anthropogenic disturbances, which greatly influence community stability. The changes in community structure, aboveground biomass (AGB), biodiversity and community stability associated with different management practices were studied with a three-year field investigation in a temperate steppe of Inner Mongolia, China. The species richness, Shannon-Wiener index, evenness, plant functional type abundance, AGB, temporal community stability, summed covariance, scaling coefficient and dominant species stability were compared among areas subjected to long-term reservation (R), long-term grazing (G), mowing since enclosure in 2008 (M) and grazing enclosure since 2008 (E). Site R had higher perennial grass abundance and lower species richness than sites G, M and E, although the AGB was not significantly different among the four sites. The species structure varied from a single dominant species at site R to multiple dominant species at sites G, M and E. The long-term reservation grassland had lower biodiversity but higher stability, whereas the enclosed grassland with/without mowing had higher biodiversity but lower stability. Different stability mechanisms, such as the compensatory dynamics, mean-variance scaling and dominant species stability were examined. Results showed that community stability was most closely related to the relative stability of the dominant species, which supports the biomass ratio hypothesis proposed by Grime.

Quantifying effects of grassland management on enteric methane emission

Data on the effect of grassland management on the nutritional characteristics of fresh and conserved grass, and on enteric methane (CH4) emission in dairy cattle, are sparse. In the present study, an extant mechanistic model of enteric fermentation was evaluated against observations on the effect of grassland management on CH4 emission in three trials conducted in climate-controlled respiration chambers. Treatments were nitrogen fertilisation rate, stage of maturity of grass and level of feed intake, and mean data of a total of 18 treatments were used (4 grass herbage treatments and 14 grass silage treatments). There was a wide range of observed organic matter (OM) digestibility (from 68% to 84%) and CH4 emission intensity (from 5.6% to 7.3% of gross energy intake; from 27.4 to 36.9 g CH4/kg digested OM; from 19.7 to 24.6 g CH4/kg dry matter) among treatment means. The model predicted crude protein, fibre and OM digestibility with reasonable accuracy (root of mean square prediction errors as % of observed mean, RMSPE, 6.8%, 7.5% and 3.9%, respectively). For grass silages only, the model-predicted CH4 correlated well (Pearson correlation coefficient 0.73) with the observed CH4 (which varied from 5.7% to 7.2% of gross energy intake), after predicted CH4 was corrected for nitrate consumed with grass silage, acting as hydrogen sink in the rumen. After nitrate correction, there was a systematic under-prediction of 18%, which reduced to 9% when correcting the erroneously predicted rumen volatile fatty acid (VFA) profile (RMSPE 15%). Although a small over-prediction of 3% was obtained for the grass herbages, this increased to 14% when correcting VFA profile. The model predictions showed a systematic difference in CH4 emission from grass herbages and grass silages, which was not supported by the observed data. This is possibly related to the very high content of soluble carbohydrates in grass herbage (an extra 170 g/kg dry matter compared with grass silages) and an erroneous prediction of its fate and contribution to CH4 in the rumen. Erroneous prediction of the VFA profile is likely to be due to different types of diets included in the empirical database used to parameterise VFA yield in the model from those evaluated here. Model representations of feed digestion and VFA profile are key elements to predict enteric CH4 accurately, and with further evaluations, the latter aspect should be emphasised in particular.

Effects of low precipitation periods on the herbage yield of mesic semi-natural grasslands under different cutting regimes

Climatic changes have led to extreme weather events, with longer dry periods affecting forage production in mesic grasslands. The effects of grassland management and years with periods of low precipitation on herbage dry matter (DM) yield were studied in two-long term grassland experiments with different cutting and fertilization regimes for the period 2000–2012. In both experiments, the annual herbage DM yields had high correlations with the amount of precipitation. The correlation was stronger in frequent cuttings regimes. The management type and the year significantly affected the herbage DM yield in both experiments. There was also a significant management × year interaction. On average, over the whole observation period, the herbage DM yield of equally fertilized treatments in experiment I was higher in treatments with two cuts per season than in treatments with more cuts. Furthermore, longer periods of low precipitation exerted fewer effects on the DM yield of the two cuts treatments compared to higher cutting frequencies. However, the increase in herbage productivity in years following seasons with low precipitation was higher in the treatments with higher cutting frequencies than in those with two cuts per season. When the treatment, cut four times per year, received a higher amount of fertilizer than the treatment, cut twice per year (experiment II), the long-term average annual herbage DM yield was higher and the yield was less decreased by longer periods of low precipitation than the two cuts per year treatment. Despite the fact that the effects of different treatments were proved in both experiments, the differences in the DM yields among the treatments in low precipitation years were not high enough to recommend best-management practices for forage production on mesic grasslands in areas subject to increasing periods of low precipitation.

Effects of grassland management, endophytic fungi and predators on aphid abundance in two distinct regions

Aims Fungal endophytes of cool-season grass species produce alkaloids toxic to herbivores, affecting food webs in agricultural and natural ecosystems. Field studies about the effects of endophytes on herbivores are rare and show contradictory results, leading to uncertain conclusions about the nature of endophyte–grass symbiosis. We asked whether the environmental contexts of local and regional scales and predation could modify the effects of endophytes on herbivores. Methods In a full factorial field experiment, we quantified the abundance of the aphid species Rhopalosiphum padi on the potted host grass Lolium perenne, which was either infected or uninfected with the endophytic fungus Neotyphodium lolii. Predators were either excluded or had free access to the pots with the aphids. One hundred and sixty grass pots were located in two regions on altogether 40 grassland sites, half of the sites intensively and half extensively managed. We tested the importance of endophyte infection, study region, management intensity of grasslands, predation and all twoway interactions on aphid abundance. Important Findings Endophyte infection reduced aphid abundance significantly in one study region only. In both regions, we found that the impacts of aphidophagous predators and grassland management intensity on aphid abundance were substantially stronger and more consistent than that of endophytes on aphid abundance. Pots excluding predators and pots placed on extensive grasslands contained higher aphid abundance. The impact of predators and management on aphid abundance were not modified by the endophyte. We conclude that the effect of endophytes on herbivores can be weak in field experiments and depends on environmental context at a regional scale. Hence, more field research efforts are necessary to detect the relative importance of endophytes and the environmental context on biotic interactions in ecosystems.

Effects of grassland management on plant communities

Grassland is an important component of agrarian landscape, providing a wide range of ecological, economic and social goods and services necessary to support life. They provide habitat for numerous plants and animals, filter sediment and pollutants before they reach our freshwater sources, increase water infiltration, prevent soil erosion, remove and store greenhouse gases, etc. Plant communities are the main elements of grassland ecosystems. The conditions of plant communities and species composition reflect the ecological conditions of the habitat and are an important bioindicator. Grassland plants have the amount requirements for ecological factors which are most suitable to them and optimal to the growth and development, however, economic activity carried out in grasslands may negatively affect the relation of ecological conditions and plants. Long-term changes of the conditions of a habitat, which are determined by various ecological factors, make an impact on the condition of plants and their competitiveness; thus species composition of communities also changes. Especially marked influence on the formation of grassland communities is made by anthropogenic factors, i.e. human economic activities (fire, drainage, fertilization, creation of sown grasslands, haymaking, grazing, or, contrariwise, abandonment). A review on the impact of anthropogenic activities on grassland plant communities is presented.

Effects of Grassland Management on Breeding Birds at the Western Edge of the Tallgrass Prairie Ecosystem in Kansas

We studied responses of breeding birds to alternative regimes for managing tallgrass prairie at the Smoky Hill Air National Guard Range in central Kansas. Species richness, diversity, and evenness did not differ among treatments, but overall abundance was highest in unburned idle (i.e., not grazed or hayed) transects, and was lowest in idle transects burned that spring. However, no treatment was either superior or inferior to all others for attracting the highest numbers of every species. Dickcissels (Spiza americana) and Henlow's sparrows (Ammodramus henslowii) were most numerous in unburned idle units, grasshopper sparrows (A. savannarum) were most abundant in grazed units and hayed units, upland sandpipers (Bartramia longicauda) were most often found in burned units, whereas eastern meadowlarks (Sturnella magna) were less abundant in burned units than in all other treatments. We conclude that the recent switch to burning idle units every 3–4 years, rather than annually, has benefitted most grassland bird species. The variety of management regimes implemented at Smoky Hill Air National Guard Range fosters heterogeneity of vegetative structure across the landscape, and thereby allows the site to provide for differing needs of various species, thus enhancing its value for grassland bird conservation.

Grassland management influences spatial patterns of soil microbial communities

Soil micro-organisms play a vital role in grassland ecosystem functioning but little is known about the effects of grassland management on spatial patterns of soil microbial communities. We compared plant species composition with terminal restriction fragment length polymorphism (T-RFLP) fingerprints of soil bacterial and fungal communities in unimproved, restored and improved wet grasslands. We assessed community composition of soil micro-organisms at distances ranging from 0.01 m to 100 m and determined taxa–area relationships from field- to landscape level. We show that land management type influenced bacterial but not fungal community composition. However, extensive grassland management to restore aboveground diversity affected spatial patterns of soil fungi. We found distinct distance–decay and small-scale aggregation of fungal populations in extensively managed grasslands restored from former arable use. There were no clear spatial patterns in bacterial communities at the field-scale. However, at the landscape level there was a moderate increase in bacterial taxa and a strong increase in fungal taxa with the number of sites sampled. Our results suggest that grassland management affects soil microbial communities at multiple scales; the observed small-scale variation may facilitate plant species coexistence and should be taken into account in field studies of soil microbial communities.

The effects of grassland management and aspect on Orthoptera diversity and abundance: site conditions are as important as management

Calcareous grasslands represent local hotspots of biodiversity in large parts of Central and Northern Europe. They support a great number of rare species which are adapted to these xerothermic habitats. Due to massive changes in land use, calcareous grasslands have become a rare habitat type and their conservation has been given a high priority in the habitats directive of the European Union. It is well known that grassland management may affect biodiversity substantially. However, the quality of calcareous grasslands is also influenced by abiotic conditions, such as aspect (i.e. sun exposure), which affects the local mesoclimate. We studied the combined effects of aspect and grassland management on Orthoptera diversity on 16 sites in Central Germany, in an unbalanced crossed design with three factors: aspect, management type and management intensity. For both response variables (diversity and abundance) we obtained a similar pattern. South-facing pastures maintained a greater diversity than north-facing pastures, but both had a greater diversity than extensively used meadows. Intensively used meadows maintained the lowest diversity and abundances. A multivariate analysis revealed that the abundance of rare Orthoptera species correlated with bare ground cover and forb cover, both of which were greatest at south-facing pastures. Our results suggest that grazing is a more suitable management for maintaining a high biodiversity in calcareous grasslands than mowing. Moreover, the mesoclimate (in this studied measured by its surrogate: aspect) is a crucial factor determining species richness and needs to be considered in reserve planning.

Effects of grassland management on soil organic carbon density in agro-pastoral zone of Northern China

The objective of this study was to estimate the soil organic carbon (SOC) in grasslands with different management measures including: (1) uncontrolled or free grazing grassland (FG); (2) grassland enclosured, excluding grazing and mowing (EG); (3) grassland enclosured and mowed early in October every year (MG) and (4) grassland enclosured under controlled grazing (CG) by examining soil bulk density and SOC content from 0 to 50 cm soil depth in agro-pastoral ecotone, Northern China. The results showed that, by implementing CG, EG and MG practices, the grasslands in agro-pastoral ecotone of Northern China achieved higher SOC storage on decade scales when compared to FG field. CG field had the highest SOC density in 0 to 50 cm soil layer, while the least SOC density was displayed by FG. However, SOC density was similar between MG and EG plots. CG increased SOC concentration by 56.08% and SOC density by 4.96 kg/m2 when compared to FG practice. In addition, it was likely to give positive financial returns in providing livestock products when compared to EG practice. CG therefore was the most feasible and benign short-term grassland management option which could deposit even higher carbon dioxide in agro-pastoral ecotone in Northern China. Key words: Agro-pastoral zone, soil organic carbon density, grassland management, Northern China.

Near-Surface Soil Property Changes Over Time as Affected by Grassland Management in the Ozark Highlands

The Ozark Highlands in the mid-southern United States is a unique physiographic region that represents a climatic and botanical transition zone from the grasslands of the dry Great Plains to the forestlands of the humid southeastern United States. Land use conversion from native prairie to managed forageland occurred extensively throughout the Ozark Highlands to the point where nearly all of the original native prairies of the once-dominant oak (Quercus species) savanna-type ecosystem have been lost. The objective of this study was to evaluate the effects of grassland management (managed foragelands and native tallgrass prairie) on changes in soil physical and chemical properties in the top 10 cm over a 6-year period in silt-loam soil. Grassland management scheme did not affect any of the suite of 19 soil properties evaluated in this study, indicating that near-surface soil physical and chemical properties in contemporary managed forageland are not degraded, but rather are quite similar to those of small tracts of remnant prairie. Averaged across management scheme, soil bulk density, pH, and extractable soil Na decreased, whereas soil electrical conductivity, extractable soil Mn, and C:N ratio increased over time. Although soil organic C was statistically similar over time, the increase in C:N ratio suggests the accumulation of soil C at a rate of approximately 130 kg ha ―1 year . The results of this study demonstrate that contemporary grasslands in the Ozark Highlands are C sinks with the present and future ability to sequester additional atmospheric C.

Management effects on the vegetation and soil seed bank of calcareous grasslands: An 11-year experiment

Calcareous grasslands, most of which are man made and therefore depend on some kind of human interference for their maintenance, are among the most species-rich communities on Earth at a small scale. For many centuries, most of these grasslands have been used as extensive pasture. However, after 1900, and particularly from 1940 onwards, livestock grazing has declined throughout Europe leading to the abandonment of low intensity grasslands over large areas. To conserve the remaining grasslands or to restore recently abandoned grasslands, better insights about the effects of grassland management on above and belowground species diversity are needed. Here, we describe the results of an 11-year experiment to investigate the role of grassland management (grazing, mowing and abandonment) in determining species composition and diversity both in the aboveground vegetation and the seed bank of a calcareous grassland in Belgium. Species diversity declined by about 60% 11 years after abandonment, from 29 species m −2 to as few as 12 species m −2. Plots that were grazed remained constant in species richness, whereas mown sites lost about 20% of their original species. Abandoned plots were largely dominated by a few grass species, in particular Festuca rubra. Concomitant with changes in the aboveground vegetation, both the number of species found in the seed bank and seed density (number of seeds m −2) had changed significantly 11 years after abandonment. Species diversity and seed density were significantly lower in abandoned plots than in grazed or mown plots. We conclude that abandonment of calcareous grasslands may lead to rapid decline of plant species diversity both in the aboveground vegetation and in the seed bank. As a result, seed banks probably have a limited role to play in the restoration of recently abandoned grasslands.