Composition Of Grasslands Research Articles

Preliminary Study of the Effect of Chemical and Organic Fertilizers on a Semi-Natural Grassland in Vlăhiţa, Harghita Mountains, Romania

AbstractThe aim of the research was to examine the effect of different fertilizers on the floristic composition and biomass yield of the semi-natural grassland used as hayfield near Vlăhița locality (Harghita County, Romania) in order to improve its management. In the same time the qualitative structure of the studied grassland was evaluated after the first application of the fertilizers. The vegetation survey was made before mowing, and a total of 84 plant taxa were identified. The studied plant community belongs to the associationFestuco-Agrostetum capillarisHorv. 1951. From the 31 fodder species, 13 had very good or good nutritional value. The qualitative structure analysis indicates that the vegetation has developed under moderate anthropogenic pressure. Beside the Euro-Asian elements the Circumpolar and the Cosmopolite elements were well represented. Many species with high tolerance for temperature, soil pH, and soil mineral nitrogen content were registered. After the first application of fertilizers in all treated plots the biodiversity increased compared to the control plot. Fertilized plots also had a significantly higher biomass yield than the control plot. All fertilizers reduced the proportion of the species with good nutritional value from the Poaceae family. Organic fertilizer affected positively the proportion of other plant families than Poaceae and Fabaceae. Long-term experiments are necessary to evaluate the response of the vegetation on treatment with organic fertilizer in order to optimize productivity of the hayfield and sustain species richness.

Land‐use legacies limit the effectiveness of switches in disturbance type to restore endangered grasslands

Temperate native grasslands in Australia have been decimated across their range since European colonization (>200 years ago), and the few remaining remnants are mostly fragmented and degraded. Changes in disturbance type, particularly the removal of Indigenous fire and the introduction of livestock grazing, resulted in the local extinction of fire‐dependent and grazing‐sensitive native species, and led to an increase in exotic species. Recently, native grasslands have been acquired to improve the reservation status of the threatened community and management strategies have been implemented that involve the removal of livestock grazing and the reintroduction of fire or other biomass reduction methods. Here, we examine if the change in disturbance type—a disturbance switch—improves the native composition of grasslands. We review literature that reports instances where there has been a change in disturbance type to examine how grasslands respond to disturbance switching. We found mostly no change in native and exotic species richness when management changed from stock grazing to fire (at least in the short term, ≤10 years). Positive outcomes for other disturbance shifts (grazing → mowing, or cultivation → grazing) occurred when the disturbance type was accompanied by seed addition, or in landscapes where dispersal from nearby remnant sites was possible. This suggests that seed‐ and/or dispersal‐limitation may limit passive restoration outcomes in fragmented landscapes. It is necessary to determine the longer‐term impacts of switches in disturbance regimes, and whether recovery thresholds have already been crossed.

Biomass Performance and Competition Effects in an Established Temperate Agroforestry System of Willow and Grassland—Results of the 2nd Rotation

Agroforestry systems (AFSs) are promoted as environmentally friendly and climate-change-resilient cultivation systems with the potential of increasing ecosystem services. Especially under temperate climatic conditions, the implementation in agricultural practice is low so far, inter alia due to the lack of knowledge regarding longer-term effects of such systems. This study investigated biomass yields and crop development during the second rotation of an alley cropping system with willows (clone “Tordis” ((Salix schwerinii x S. viminalis) x S. vim.)) and grassland that was established in March 2011, as reported in a former study of the authors. Two grassland swards (white clover grass (Lolium perenne L. and Trifolium repens L.) (CG) and a diversity mixture with 32 plant species (DIV)) were proven in an intensive (3/4 cuts per year) and extensive management system (two cuts per year). Total yield (sum of three years) of AFS increased substantially in the second rotation (year four to six after establishment of the AFS). This was particularly due to a fivefold increase in woody biomass. At the same time, yields of grassland biomass decreased slightly. Biomass of CG outperformed DIV, especially in the intensive managed systems with a dry matter (DM) yield of 18 t ha−1, compared to 12.6 t ha−1. However, AFS grassland yields were always lower than yields of reference areas with grassland in pure stand. Nevertheless, lower yields are probably caused by competition effects between woody crops and grassland. Grassland yields along transects across the grassland alleyways showed a strong decrease in the border areas in all treatments. Higher grassland yields in the alley center did not compensate yield reductions in border areas. Furthermore, the botanical composition of grassland was modified in border areas with reduced legume DM contribution and increases of both grasses and forbs. Thus, the width of grassland alleys with 9 m caused strong competition effects by the willows.

Frequent burning maintained a stable grassland over four decades in the Drakensberg, South Africa

The mesic montane grasslands of the uKhahlamba-Drakensberg, which produce cured flammable fuel, have evolved under and are sustained by recurrent fires. The Brotherton burning trial (12 replicated treatments) was established at Cathedral Peak (1 890 m asl) in 1980 to understand how burn season and frequency control the composition and diversity of the montane catchment grassland. Multivariate methods were used to examine the long-term (almost 40 years). compositional stability under different burning regimes. The species composition deviated steadily and markedly from the initial state (Bray–Curtis dissimilarity) by 43.4 ± 9.32% with quinquennial burning (alternating autumn/spring) and by 64.6 ± 2.24% with attempted fire exclusion (three unplanned burns). Composition was rapidly transformed (by 53.1 ± 4.6%) by biennial summer burning (discontinued in 1991). Dominance shifted from Themeda triandra to other grasses (Stiburus alopecuroides, Tristachya leucothrix, Harpochloa falx) with biennial summer and infrequent burning. In contrast, regular dormant season burning annually or biennially (in autumn, winter, or spring) maintained a stable grassland close to the original composition (mean deviation 23.08%). Burning homogenised the composition, overriding the initial extant small-scale spatial variation. Results support the current practice to burn biennially in the dormant season to maintain stable grassland in the Drakensberg catchments.

Effects of fertilization and irrigation on vascular plant species richness, functional composition and yield in mountain grasslands

Land-use intensification is a major threat to biodiversity in agricultural grasslands and fertilization is one of the main drivers. The effects of fertilization on biodiversity and plant functional composition (community-weighted mean traits and mean ecological indicator values) are well studied in lowland regions, but have received less attention in mountain grasslands. Moreover, in inner-alpine dry valleys, fertilizer is often applied in combination with irrigation, and irrigation effects are less well known. We experimentally tested the effects of fertilization and irrigation on vascular plant species richness and the functional composition of mountain grasslands in the Swiss Alps. After five years, fertilization increased yield but the relationship was quadratic with maximum yield reached at intermediate fertilizer levels (58 kg N ha−1year−1). The species richness of all vascular plants and forbs decreased, on average, by 6 and 5 species respectively, per 50 kg N of extra fertilizer (ha−1 year−1) applied. Fertilization also favored fast-growing plants (increased mean specific leaf area) and plants typically found in productive environments (increased mean indicator values for soil productivity and moisture). In contrast, we found no effects of irrigation on plant community composition, which suggests that irrigation does not affect vascular plant diversity to the same extent as fertilization in these mesic mountain hay meadows, at least in the mid-term. Our finding that maximum yield can be achieved at intermediate fertilizer levels is very important from an applied, agronomical and conservation point of view. It suggests that without loss of yield, farming costs and at the same time environmental pollution and negative effects on biodiversity can be reduced by applying less fertilizer. We therefore recommend maintaining non-intensive land use and keeping fertilizer inputs as low as possible to maintain the high plant diversity of mountain grasslands.

Carbon uptake changed but vegetation composition remained stable during transition from grazing to mowing grassland management

Grasslands could play an important role in supporting livestock, in carbon sequestration and in biodiversity conservation. Different grassland managements may change the vegetation composition of grasslands, which could alter these ecosystem services. We studied the effects of grazing vs. mowing on the vegetation composition (2012–2016) and on the carbon uptake (2011–2013) of sandy grasslands in Hungary to study if the vegetation composition differs and if it does, whether it affects carbon uptake. To observe differences in vegetation composition between the two types of management regimes we performed fine-scale vegetation survey in adjacent grazed and mowed sites. We compared species compositions and vegetation diversity indices between the management regimes based on permutational ANOVA, mixed effect model and information theory models. We used fine-scale vegetation survey because it has the potential to indicate vegetation changes within six years as changes in species richness and diversity are usually detected after 10–20 years. Carbon uptake was measured in parallel with eddy covariance technique at both sites. In spite of the contrasting management regimes the vegetation composition was stable (no differences observed in the diversity indices), while carbon uptake was significantly greater in the grazed (sink: +1 ± 0.7 t C ha−1 year−1) compared to the mowed site (source: -0.3 ± 0.6 t C ha−1 year−1). The vegetation was heterogeneous (patchy) and had a high species richness at both sites (grazed: 91 species ha−1, mowed: 90 species ha−1) which might have contributed to the stability of the vegetation composition. We concluded that differences in carbon uptake existed between the grazed vs. mowed sites due to biomass removal intensity with no differences in the vegetation composition.

Rapid loss of leguminous species in the semi-arid grasslands of northern China under climate change and mowing from 1982 to 2011

Effects of mowing on the composition and diversity of grasslands varied with climate change (e.g., precipitation and temperature). However, the interactive effects of long-term mowing and climate change on the diversity and stability of leguminous and non-leguminous species in the semi-arid grasslands are largely unknown. Here, we used in situ monitoring data from 1982 to 2011 to examine the effects of continuous mowing and climate change on the plant biomass and diversity of leguminous and non-leguminous species, and soil total nitrogen in the typical semi-arid grasslands of northern China. Results showed that the biomass and diversity of leguminous species significantly decreased with the increasing in the biomass and diversity of non-leguminous species during the 30-a period. Variations in biomass were mainly affected by the long-term mowing, while variations in diversity were mainly explained by the climate change. Moreover, the normalized change rates of diversity in leguminous species were significantly higher than those in non-leguminous species. Mowing and temperature together contributed to the diversity changes of leguminous species, with mowing accounting for 50.0% and temperature 28.0%. Temporal stability of leguminous species was substantially lower than that of non-leguminous species. Consequently, soil total nitrogen decreased in the 2000s compared with the 1980s. These findings demonstrated that leguminous species were more sensitive to the long-term mowing and climate change than non-leguminous species in the semi-arid grasslands. Thus, reseeding appropriate leguminous plants when mowing in the semi-arid grasslands may be a better strategy to improve nitrogen levels of grassland ecosystems and maintain ecosystem biodiversity.

Ecological Evaluation of Grassland Vegetation in Hodrušská Hornatina Highland

Abstract In the submitted paper, we have analysed the results of a systematic survey of grassland communities, performed in Hodrušská hornatina highland, in Štiavnické vrchy mountains. The main aims of the research were: i) syntaxonomical classification of grassland vegetation; ii) analysis of the main ecological gradients in species composition; iii) evaluation of the influence of environmental factors on species composition of grasslands. The dataset included 153 phytosociological relevés recorded on grasslands. Grassland communities were classified within five associations: Holcetum lanati, Pastinaco sativae-Arrhenatheretum elatioris, Alchemillo-Arrhenatheretum elatioris, Anthoxantho odorati-Agrostietum tenuis, Onobrychido viciifoliae-Brometum erecti; and the successional and transitional stages belonging to alliances Arrhenatherion elatioris and Bromion erecti. The results of the Detrended Correspondence Analysis support our assumption that the main environmental gradient in species composition on grassland is related to moisture. The results of the Redundancy Analysis show that all used environmental variables explained 3.4% of the variability of the species data. The most important factors affecting the species composition were altitude, slope, distance from settlements, and management.

Species Monitoring Using Unmanned Aerial Vehicle to Reveal the Ecological Role of Plateau Pika in Maintaining Vegetation Diversity on the Northeastern Qinghai-Tibetan Plateau

Plateau pika (Ochotona curzoniae, hereafter pika) is considered to exert a profound impact on vegetation species diversity of alpine grasslands. Great efforts have been made at mound or quadrat scales; nevertheless, there is still controversy about the effect of pika. It is vital to monitor vegetation species composition in natural heterogeneous ecosystems at a large scale to accurately evaluate the real role of pika. In this study, we performed field survey at 55 alpine grassland sites across the Shule River Basin using combined methods of aerial photographing using an unmanned aerial vehicle (UAV) and traditional ground measurement. Based on our UAV operation system, Fragmentation Monitoring and Analysis with aerial Photography (FragMAP), aerial images were acquired. Plot-scale vegetation species were visually identified, and total pika burrow exits were automatically retrieved using the self-developed image processing software. We found that there were significant linear relationships between the vegetation species diversity indexes obtained by these two methods. Additionally, the total number of identified species by the UAV method was 71, which was higher than the Quadrat method recognition, with the quantity of 63. Our results indicate that the UAV was suitable for long-term repeated monitoring vegetation species composition of multiple alpine grasslands at plot scale. With the merits of UAV, it confirmed that pika’s disturbance belonged to the medium level, with the density ranging from 30.17 to 65.53 ha−1. Under this density level, pika had a positive effect on vegetation species diversity, particularly for the species richness of sedge and forb. These findings conclude that the UAV was an efficient and economic tool for species monitoring to reveal the role of pika in the alpine grasslands.

Frequent planned fire can prevent succession to woody plant dominance in montane temperate grasslands

AbstractNatural temperate grasslands are endangered throughout their range, largely because of their almost complete conversion to agriculture, and by changes in fire and grazing regimes. Woody encroachment by shrubs is a global threat to the structure, function and composition of grasslands. We wished to determine the characteristics of fire regimes that prevent or reverse woody plant encroachment, maintain native species richness and minimise exotic plant invasion in temperate grassland at the Surrey Hills Tasmania, where a fire management plan with variable prescriptions had been implemented for two decades. We collected floristic, fire regime and environmental data from 105 quadrats (1 × 10 m) in 2016/2017, and compared the data from 2016/2017 to that from a 1994 survey using the same methods. A high frequency and cover of native shrubs characterised areas unburned for at least 20 years before 2017, but not those unburned in the 20 years before 1994. Shrub cover began to strongly increase after a decade without fire and was greater on larger plains. Native species richness declined with an increasing minimum interval between fires and increased with elevation. It began to decline at the quadrat scale when shrub cover attained 40%. In the data set as a whole, 17 of the 67 most abundant taxa were absent from all quadrats unburned for 20 years before 2017, indicating a high potential for loss of species at a landscape scale in the absence of fire. Exotic species cover was randomly distributed in relation to fire regimes and environment. The current fire management regime has largely been at a sufficient frequency and minimum interval (approximately a decade between fires) to maintain the grassiness and native species richness of treated plains, which is fortunate given that recent land‐use change appears to have resulted in increased frequency of shrubs independent of their cover.

Community composition, beta diversity and structure of high altitude grasslands along an altitudinal gradient in southeastern Brazil

Introduction: Studies on how the altitudinal gradient determines community composition and structure in tropical high altitude grasslands are limited. Objective: To evaluate the plant community composition and structure and their relationship with altitude and soil properties along an altitudinal gradient of three granitic rocky outcrops at the Serra do Brigadeiro State Park, Minas Gerais, in southeastern Brazil. Methods: In each selected site, 100 plots of 1 × 1 m were established, totalizing 300 plots in the study area. We compared floristic composition, relative coverage and abundance among sites. We performed beta diversity analysis. We also performed an indicator species analysis and a canonical correlation analysis to investigate possible relations between abiotic (soil and altitude) and biotic (indicator species abundances) variables. Results: We sampled a total of 9 276 individuals belonging to 39 families and 102 species. Significant differences were observed among sites regarding composition, abundance and coverage. The indicator species analysis revealed that 57 species (55.88 %) were indicators. The distribution of indicator species abundances was correlated with environmental variables. Conclusions: It was observed that altitude and soil play an important role in controlling community composition and structure, beta diversity and species distribution in the highland grasslands studied.

Survival of Sharp‐Tailed Grouse Under Variable Livestock Grazing Management

ABSTRACTLivestock grazing is a predominant land use worldwide and can influence wildlife populations by altering grassland composition, structure, and productivity. Conceptually, rest‐rotation livestock grazing could increase pasture‐level heterogeneity that would allow wildlife to balance the need for resources with the risk of predation. Prairie‐grouse (Tympanuchus spp.) are recognized as important indicator species for grassland ecosystems, so identifying management approaches suitable for prairie‐grouse could have implications for other species. We monitored radio‐collared female sharp‐tailed grouse (T. phasianellus) to evaluate the effects of 3 systems of livestock grazing management on the breeding season survival and habitat‐associated mortality risk of adult grouse in the northern mixed‐grass prairie in eastern Montana and western North Dakota, USA, during 2016–2018. Cumulative breeding season survival was 0.65 ± 0.04 (SE) and annual survival varied from 0.28 ± 0.04 to 0.50 ± 0.05. Grazing management did not have a meaningful influence on any aspect of the cumulative breeding season survival of adult female sharp‐tailed grouse, although the seasonal timing of peaks in mortality risk differed among systems. A 10% increase in cropland increased mortality risk of adult female sharp‐tailed grouse by a factor of 1.27. Overall, our results suggest that strategies that preserve economically viable ranching systems in unfragmented grasslands may have greater benefits for sharp‐tailed grouse survival than prescriptive livestock grazing systems. © 2020 The Wildlife Society.

Soil and vegetation dynamics in a chronosequence of abandoned vineyards

Euro-Mediterranean countries have undergone radical changes in their traditional landscapes due to the abandonment of rural areas. Natural vegetation rapidly colonizes abandoned lands and cause changes in ecosystem functioning. Our main objective was to study how time since abandonment of vineyards influences the physical, chemical and biological properties of the soil and the vegetation composition and cover. In 2016, we selected a chronosequence of six abandoned vineyards (1, 3, 7, 11, 25 and 40 years), an active vineyard, and a plot of land that has not been used as a vineyard for at least the last 60 years. Soil physical-chemical variables, including the organic matter fractions and available nutrients, were analysed. To observe the variation in the biochemical properties of the soils, the activities of 11 enzymes were determined, relating to the main macronutrient cycles: carbon (C), nitrogen (N), phosphorous (P) and sulphur (S) cycling. Three sites (1 m2) were randomly established on each plot within the area occupied by annual grasslands, and species cover was estimated in order to obtain the species density and cover of plant functional traits. Our results showed that the abandonment caused major changes in the functioning of the ecosystems. Secondary succession in abandoned vineyards was characterized by a significant increase in plant species density and by changes in the composition of the annual grasslands, from an early brassicaceous community to a late cistaceous community. This was accompanied by an increase in soil TOC (0.38–1.78%) and TN (0.14 to 0.26 %) content, and the activity of most enzymes. These changes occurred more rapidly during the first two decades after abadonment.

Relative hierarchy of farming practices affecting the fatty acid composition of permanent grasslands and of the derived bulk milk

This study aimed (i) to assess the relative weight of different predicting variables, related to site and grassland characteristics, in determining the fatty acid (FA) composition of permanent grasslands and (ii) to verify if and at which extent the same variables have a significant predicting role for the FA composition of the derived bulk cow milk.Available data collected from 2003 to 2016 by three European research institutions were used. A dataset (n = 144) was built up including: (i) the proximate and FA compositions of herbage, (ii) site altitude and climatic conditions, (iii) grasslands botanical composition (main family groups), herbage phenology and growing cycle, (iv) herd characteristics and (v) milk gross and FA compositions.Prediction models for herbage FA profile were highly reliable (R2 adjusted ≥ 0.80) for C18:3 n3, total monounsaturated FA and total polyunsaturated FA (Σ PUFA). Reliable predictions (R2 adjusted ≥ 0.60) were obtained for the other main herbage FA. The relative predicting weight was higher for phenology and proximate composition than for botanical composition. Among proximate composition variables, dry matter showed the highest relative weight in determining the majority of the predicting models.Prediction models for milk FA profile were reliable (R2 adjusted ≥ 0.60) for Σ de novo FA, C16:0, C18:3 n3, total even-chain saturated FA (Σ ECFA), Σ PUFA and the C18:1 c9/C16:0 ratio, while they were moderately reliable (R2 adjusted ≥ 0.50) for C18:1 t10+t11, C18:2 n6, C18:2 c9t11 and the C18:2 n6/C18:3 n3 ratio. Diet composition, site altitude and grazed grassland features concurred to predict milk FA. Fresh herbage proportion in the diet played a relevant role in determining the milk proportion of several FA. Phenology was the main driver for the C18:2 c9t11 and Σ PUFA proportions, negatively affecting them. Herbage phenology fitted milk FA better than proximate and botanical compositions.

Soil seed bank in a subtropical grassland under different grazing intensities

ABSTRACT Grazing is an important determinant for the composition and structure of grasslands; however, soil seed bank (SSB) response to grazing intensity is poorly investigated. We analyzed SSB richness and density in a subtropical grassland in southern Brazil with different forage offers (low, intermediate, high and very high), that is, contrasting grazing intensities. The SSB was evaluated by the seedling emergence method. We collected ten SSB samples at two layers (0-5 and 5-10 cm) in spring and autumn in each of grazing intensity treatments. We surveyed the established vegetation to assess its similarity with the SSB. Treatment effects were analyzed by Poisson regression while compositional differences were visualized by ordination. We found 103 species in the SSB, of which 71 were also found in established vegetation. We found a positive correlation between SSB density and grazing intensity. High grazing intensity influences patterns of composition and dominance in the SSB, while no strong differences were found among the other treatments. The SSB was characterized by low participation of dominant grasses in the vegetation and the dominance of ruderal species, indicating that recovery from the SSB after total removal of vegetation (severe disturbance) may be limited in grasslands in the region.

Environmental and management drivers of alpine grassland vegetation types

Current vegetation of alpine grasslands has been shaped by the combination of natural ecological factors (such as climate, soil, topography) and human activities, mainly represented by animal grazing and agricultural practices. An assessment of these factors can explain the present composition of plant communities and help to evaluate the future development of rangeland vegetation. Nowadays, the analysis of the botanical composition of grasslands is of a major importance in order to propose appropriate management plans for the sustainable exploitation of pastoral resources and their future conservation. The main purpose of this work was to assess the relevance of ecological and management factors in alpine grasslands in an area located in eastern Italy, currently used for extensive grazing, and to describe the main factors that affect the characteristics of pasture types. To this aim, about 900 ha of alpine grasslands were surveyed in Val Visdende (northern Veneto, province of Belluno, Italy) by means of 189 linear transects. Some environmental variables (altitude, slope, aspect) and factors related to management (pastoral value, animal excreta, distance from night barns) were collected for each botanical transect. Landolt indicators were calculated in order to evaluate the ecological space occupied by each type. This assessment made it possible to identify the most relevant grassland communities (namely nutrient poor, shrub encroached, nutrient rich and humid pastures) occurring in the studied area, the effectiveness of ecological indicators to describe and to differentiate vegetation groups and the effect of animal management and ecological factors in the discrimination of grassland types.

Nigritella lithopolitanica Ravnik (Orchidaceae): morphological and ecological differences among populations and factors contributing to its endangerment

ABSTRACT The rare orchid, Nigritella lithopolitanica is endemic to species-rich mountain grasslands of the south-eastern Alps with the majority of its distribution area in Slovenia. We examined phenotypic variation in morphological and reproductive traits among seven of 16 extant populations in relation to the floristic composition and stature of the grasslands surrounding these plants. Inflorescence length varied the least among populations and was uncorrelated with either habitat characteristics or location. This stability presumably reflects its reliance on specialized pollinators. Other traits display appreciable variation among populations and covary with grassland composition and stature. Taller plants occur within taller swards and allocate more to vegetative growth and less to reproduction. The presumably reflects an adaptive trade-off to enable competitive success under competitive conditions. We conclude that N. lithopolitanica has low competitive potential and thrives best on sites with thin soils, some stone cover, and in open, low-density swards of vegetation where competing grasses are shorter. Grazing appears to favour this species whereas the recent human removal of stones from these habitats represents a clear threat to the persistence of this rare species.

Enhancement of palatable perennial grasses by disturbance and seed addition in degraded native grasslands of the dry pampas in Central Argentina

Land use has changed the original composition of the natural grasslands in the dry pampas of central Argentina, to the detriment of palatable perennial grasses (PPG). Long-term elimination of anthropogenic disturbances has not been enough to effectively recover the PPG, which suggests that availability of seeds and/or habitats may be limiting their recruitment. Therefore, our objectives in a degraded grassland site were to assess: (1) the germinable soil seed bank and (2) changes in botanical composition after addition of PPG seed following canopy disturbance. In autumn 2015, we randomly selected 10-paired plots, measured the aboveground biomass and took soil samples to assess the germinable soil seed bank. Afterwards, we disturbed the resident vegetation in each paired plot and either added PPG seeds or left the plot without any seed addition as a control. We quantified the seedling density of seeded and spontaneous species in the spring of 2015 and 2016, and the aboveground biomass at the end of 2017. Annual grasses and forbs (AGFS) dominated the soil seed bank, while PPG and unpalatable perennial grasses (UPG) occurred at low seed density and richness. Addition of PPG seeds resulted in the successful establishment of one key seeded PPG (Poa ligularis). In the spring 2017, the aerial biomass of PPG was highest in the seeded plots, where P. ligularis accounted for 94%. Our results showed that PPG were poorly represented in the soil seed bank of the degraded grassland and that disturbance of the resident vegetation combined with PPG seed addition enabled successful recruitment of a key PPG. So, enhancement of the pastoral value of degraded dry pampas grasslands would be possible through disturbance of the resident vegetation and addition of PPG seed.

Impact of Seriphium plumosum densification on Mesic Highveld Grassland biodiversity in South Africa.

Mesic Highveld Grassland is important for biodiversity conservation, but is threatened by bush densification from Seriphium plumosum. This indigenous densifier spreads rapidly and outcompetes other herbaceous species, changing the species composition and structure of grasslands. This study looks at three different densities of S. plumosum and how these affect grassland biodiversity within Telperion, Mpumalanga, South Africa. An intermediate density of S. plumosum (1500 individuals (ind) ha−1) resulted in the highest plant species diversity (H = 2.26), a low density (24 ind ha−1) was moderately diverse (H = 1.96) and a high density (9500 ind ha−1) was least diverse (H = 1.78). There were differences between the three densities in terms of plant species diversity, with the intermediate density being significantly more diverse (p < 0.01) than both the low and high densities. Findings indicate that there was a significant difference between the sites in terms of ecological successional status (p < 0.01). The presence of S. plumosum at low densities can be considered an integral part of the environment. It is important that in areas where S. plumosum occurs, it should be monitored. If this species is not in balance within its environment and it starts becoming dense, it will negatively affect the biodiversity, species composition and structure of the habitat.

High resistance of plant biodiversity to moderate native woody encroachment in loess steppe grassland fragments

AbstractQuestionsWoody encroachment affects many open habitats from semi‐deserts to wetlands and grasslands. We aimed to study the effect of native woody encroachment on grassland plant biodiversity in loess steppe fragments by analysing the vegetation composition of grasslands subjected to increasing levels of encroachment. We studied both ancient and restored grasslands with the following research hypotheses: (a) increasing woody encroachment decreases total diversity and the species richness of dry‐grassland species; and (b) the effect of woody cover on grassland biodiversity differs between ancient and restored grasslands.LocationSouth‐Eastern part of Transdanubia, Hungary, Central Europe.MethodsAltogether 63 loess grassland fragments were selected for the study. The percentage cover of trees, shrubs and herbaceous vegetation were recorded in 400‐m2‐sized plots (n = 110). The effects of woody encroachment and grassland age on diversity, total species richness of the herb layer, and richness of dry‐grassland species were analysed.ResultsWe found that woody encroachment affected the total richness of the herb layer and the species richness of dry‐grassland species. For most of the listed variables, lowest values were found for the highest woody encroachment groups. Grassland age affected the species richness of the herb layer and that of dry‐grassland species; lower values were detected in restored grasslands. In restored grasslands, Shannon diversity and species evenness were lower, while Berger–Parker dominance was higher than in ancient grasslands. Species composition and richness displayed a relatively high resistance to moderate woody encroachment; the highest decrease in diversity was detected at a high level of woody encroachment (&gt;52% of woody cover).ConclusionsWe can conclude that low to moderate woody encroachment cannot be simplistically regarded as degradation. Results suggest that moderately encroached loess grasslands can be easily restored by the suppression of woody species, as their species pool still contains many dry‐grassland species targeted for restoration.