Long-term effect of sheep and goat grazing on plant diversity in a semi-natural dry grassland habitat

Long-term effects of environmental alterations in protected grasslands – Land-use history determines changes in plant species composition

Traditional management practices are essential for maintaining the biodiversity of many semi-natural grassland habitats. Abandonment of these practices is leading to shrub encroachment and a decline in biodiversity in many European regions. For this reason, understanding the social processes behind transforming traditional management practices and the subsequent habitat changes is currently a major focus of ecological research. We aimed to identify ecologically relevant indirect drivers (economic, demographic, institutional, cultural, and technological) impacting Natura 2000 grassland habitats since the mid-twentieth century in two neighbouring Central European post-communist countries, Hungary and Romania. Ecological memory on 21 semi-natural grassland localities was collected through 60 oral history interviews from knowledgeable locals. The studied localities were covered by semi-natural grasslands listed in the Habitats Directive, Annex I: 1.) Semi-natural dry grasslands (6210); 2.) Alluvial meadows of river valleys (6440); and 3.) Pannonic salt steppes and salt marshes (1530*). We asked about three time periods (before: 1950-1961, during: 1962-1989, and after socialist collective farming: 1990-2007). We identified 211 mentions of indirect drivers and categorised them into five main indirect driver categories. Economic drivers were the most often mentioned indirect driver categories for alluvial and saline habitats. Demographic drivers, such as ageing, labour shortage, and rural-urban migration, were highly intertwined and most pronounced for dry semi-natural grasslands. We found that the impacts of ecologically relevant social processes beginning in the 1960s-1970s became visible only decades later, reflected by delayed changes in grassland management and vegetation (e.g. shrub encroachment, spread of weeds and invasive species). Migration to cities was amplified by changing lifestyles and values, leading to a decrease in the village labour force and a consequent ageing of inhabitants, ultimately resulting in a major decline in livestock numbers and in traditional management practices. We argue that the decline of grassland management in the 1990s and 2000s was driven by long-term social processes that began in the 1960s. We argue, that appropriate subsidy schemes and governance models are essential to support surviving traditional farming practices, integrate biodiversity conservation with cultural heritage, and sustain innovative rural communities transitioning within Europe's marginalised agricultural landscapes.

Arbuscular mycorrhizal fungi (AMF) are expected to be one of the key drivers determining the diversity of natural plant communities, especially in nutrient-poor and dry habitats. Several previous studies have explored the importance of AMF for the composition of plant communities in various types of habitats. Surprisingly, studies of the role of AMF in nutrient-poor dry grassland communities dominated by less mycotrophic plant species are still relatively rare. We present the results of a 3-year study in which a plant community in a species-rich dry grassland was subjected to the fungicide carbendazim to suppress AMF colonization. We tested the effect of the fungicide on the following parameters: the plant species composition; the number of plant species; the cover of the rare, highly mycorrhiza-dependent species Aster amellus; the cover of the dominant, less mycorrhiza-dependent species Brachypodium pinnatum; and the cover of graminoids and perennial forbs. In addition, we examined the mycorrhizal inoculation potential of the soil. We found that the suppression of AMF with fungicide resulted in substantial changes in plant species composition and significant decrease in species richness, the cover of A. amellus and the cover of perennial forbs. In contrast the species increasing their cover after fungicide application were graminoids—the C3 grasses B. pinnatum and Bromus erectus and the sedge Carex flacca. These species appear to be less mycorrhiza dependent. Moreover, due to their clonal growth and efficient nutrient usage, they are, most likely, better competitors than perennial forbs under fungicide application. Our results thus suggest that AMF are an essential part of the soil communities supporting a high diversity of plant species in species-rich dry grasslands in nutrient-poor habitats. The AMF are especially important for the maintenance of the populations of perennial forbs, many of which are rare and endangered in the area.

In the last decade, it has become scientifically evident that the insular dry grasslands of the Carpathians and the Transylvanian Depression in Romania represent biodiversity hotspots. These semi-natural dry grassland habitats are traditional cultural landscapes resulting from low-intensity land-use practices over centuries. Nowadays, changes in land use, such as agricultural intensification, cessation of traditional management, long-term abandonment, and a lack of public and policy-maker awareness of their importance, constitute factors that threaten these high natural value grasslands. Consequently, their distribution has become insular and isolated. Therefore, in order to preserve these valuable grasslands, it is imperative to explore and implement effective conservation strategies. The significance of ecosystems is evident from the presence of specific motifs in Romanian folk culture that reflect the diversity of Transylvanian grasslands. Moreover, public awareness has been raised in recent years by national and international celebrities who have visited or showcased the Transylvanian grasslands in their activities. To raise public awareness about Transylvanian dry grasslands and to ex situ conserve them, we constructed a small dry grassland plot within the “Vasile Fati” Botanical Garden in Jibou, Romania. This project aligns with other ongoing conservation activities at the “Vasile Fati” Botanical Garden of the Biological Research Center in Jibou, including the conservation of endangered plant species and traditional Romanian fruit trees, especially apple trees, as well as educational activities in the fields of ecology, botany, and zoology.

Stimulation of nitrification and denitrification by long term (from years to decades) grazing has commonly been reported in different grassland ecosystems. However, grazing generally induces important changes in plant species composition, and whether changes in nitrification and denitrification are primarily due to changes in vegetation composition has never been tested. We compared soil nitrification- and denitrification-enzyme activities (NEA and DEA, respectively) between semi-natural grassland sites experiencing intensive (IG) and light (LG) grazing/mowing regimes for 13 years. Mean NEA and DEA (i.e. observed from random soil sampling) were higher in IG than LG sites. The NEA/DEA ratio was higher in IG than LG sites, indicating a higher stimulation of nitrification. Marked changes in plant species composition were observed in response to the grazing/mowing regime. In particular, the specific phytomass volume of Elymus repens was lower in IG than LG sites, whereas the specific volume of Lolium perenne was higher in IG than LG sites. In contrast, the specific volume of Holcus lanatus, Poa trivialis and Arrhenatherum elatius were not significantly different between treatments. Soils sampled beneath grass tussocks of the last three species exhibited higher DEA, NEA and NEA/DEA ratio in IG than LG sites. For a given grazing regime, plant species did not affect significantly soil DEA, NEA and NEA/DEA ratio. The modification of plant species composition is thus not the primary factor driving changes in nitrification and denitrification in semi-natural grassland ecosystems experiencing long term intensive grazing. Factors such as trampling, N returned in animal excreta, and/or modification of N uptake and C exudation by frequently defoliated plants could be responsible for the enhanced microbial activities.

Global warming has been strongly accelerating in the last decades. Climate models tell us that this trend will continue in the future, accompanied by a marked decline in precipitation in Southern Europe, whereas the Alps will likely receive more winter and less summer precipitation. Climate factors and additionally nitrogen deposition and land-use changes have been identified as global change factors posing threats on high-mountain biodiversity, ecosystem stability and services. On the other hand, the characteristic micro-topographic variability of high mountain ecosystems may buffer them against global change impacts. Monitoring data from European mountain peaks show that changes in biodiversity patterns are closely related to rising temperatures. However, the effects of climate change on plant biodiversity differ significantly between temperate and Mediterranean biomes with species richness increases synchronously with warming in the former and richness decreases in the latter. The MediAlps project aimed at disentangling anthropogenic and natural factors underlying differential changes in plant species composition and richness observed on mountain summits in the European Alps and the Mediterranean biome at the local and regional spatial scale. Changes in plant species richness and composition and present land-use impact based on systematic field observations were recorded on long-term monitoring plots on 23 summits. Soil temperature, water potential and local dry nitrogen deposition were measured in situ. Topographic parameters were recorded with photogrammetric methods. At the regional level, climate data and regional nitrogen deposition data from online resources (CHELSA, EMEP) were used and past land-use impact was assessed via guideline-aided semi-structured interviews. (Generalized) linear mixed-effects models and structural equation models (SEM) were employed to assess the impact of these drivers on biodiversity changes. Furthermore, spatio-temporal analyses based on satellite images were conducted. Climate change is and will probably continue to be the main driver of plant biodiversity, species composition and their changes on mountain summits in both biomes. However, there are biome-specific differences with precipitation playing an important role in the Mediterranean biome in addition to temperature, which clearly is the most important single factor in the temperate biome. These changes will likely lead to a further thermophilisation in both biomes. The upwards movement of species from lower elevations will likely also result in a biotic homogenization of the vegetation, exacerbated by the decline of high-elevation endemic species. Species richness will likely continue to increase in the temperate biome until the “pay-off” of extinction debts or threshold effects of population size on extinction risks set in. With decreasing precipitation species richness in the Mediterranean biome will probably decline in the long run, too. Nevertheless, other anthropogenic drivers have to be considered as well, although their influence is arguably much smaller than that of climate variables, namely nitrogen deposition with a negative influence on species richness change in the temperate biome and present land-use with a positive one in the Mediterranean biome. In addition to MediAlps’ main focus on comparing multiple anthropogenic ecological drivers in the Alps with the Mediterranean mountains, the project substantially contributed to a spatially larger scaled long-term observation effort in the frame of the GLORIA (Global Observation Research Initiative in Alpine Environments) program.

The study was conducted to assess the effect of conventional, integrated and organic management on differences in plant species composition, richness and diversity. The plants were studied in triads of orchards situated in three regions of the Czech Republic. Data about species occurrences were collected on 15 permanent plots in the tree rows and 15 plots between tree rows in each of the apple orchards during 2009. A total of 201 vascular plant species (127 native species, 65 archaeophytes, and 9 neophytes) were found. Management type and also different regional conditions had a significant effect on plant species composition and on diversity parameters of orchard spontaneous vegetation. Species richness and species pool was significantly higher in the organic orchards than in the differently managed orchards. Management type had significant effect on proportions of archaeophytes, and also neophytes in apple orchards. The results showed that a change from conventional to integrated and organic management in apple orchards lead to higher plant species diversity and to changes in plant species composition.

The Rengen Grassland Experiment (RGE), set up on a Nardus grassland in 1941, consists of a control and five fertilizer treatments (Ca, CaN, CaNP, CaNP-KCl and CaNP-K2SO4). In 2005, soil chemical properties were analyzed to investigate the effect of soil variables on biomass production, plant species composition and species richness of vascular plants. Further, the effect of sampling scale (from 0.02 to 5.76 m2) on species richness was investigated. Soil properties (plant-available contents of K, P, C:N ratio, and pH) and biomass production were found to be strictly dependent on the fertilizers applied. Diversification of soil P content between treatments with and without P application is still in progress. Biomass production was most positively affected by P and K soil contents under N application. Furthermore, pH had a small positive effect on biomass production, and C:N ratio a moderately negative one. Two types of nutrient limitation were recognized: (1) limitation of total biomass production and (2) limitation of individual plant species. Long-term addition of a limiting nutrient affected the grassland ecosystem in three ways: (1) causing a change in plant species composition without significant increase in total biomass production, (2) causing no change in species composition but with significant increase in total biomass production, and (3) causing substantial change in plant species composition accompanied by significant increase in total biomass production. The explanatory power of all measured soil properties on plant species composition was almost the same as the power of the treatment effect (61.7% versus 62% of explained variability in RDA). The most powerful predictors of plant species composition were soil P, K and Mg contents, pH, and biomass production. The soil P content and biomass production were the only variables leading to a significant negative effect on species richness. An almost parallel increase in species richness with increasing sampling area was detected in all treatments. Constant differences among treatments were independent of sampling area.

Effect of fertiliser application and cutting regime on temporal differentiation of mesic semi-natural grassland vegetation

Monitoring the rapid and extensive changes in plant species distributions occurring worldwide requires large-scale, continuous and repeated biodiversity assessments. Imaging spectrometers are at the core of novel spaceborne sensor fleets designed for this task, but the degree to which they can capture plant species composition and diversity across ecosystems has yet to be determined. Here we use imaging spectroscopy and vegetation data collected by the National Ecological Observatory Network (NEON) to show that at the landscape level, spectral beta-diversity—calculated directly from spectral images—captures changes in plant species composition across all major biomes in the United States ranging from arctic tundra to tropical forests. At the local level, however, the relationship between spectral alpha- and plant alpha-diversity was positive only at sites with high canopy density and large plant-to-pixel size. Our study demonstrates that changes in plant species composition and diversity can be effectively and reliably assessed with imaging spectroscopy across terrestrial ecosystems at the beta-diversity scale—the spatial scale of spaceborne missions—paving the way for close-to-real-time biodiversity monitoring at the planetary level.

The expansion of the agricultural frontier by the clearing of remnant forests has led to human-dominated landscape mosaics. Previous studies have evaluated the effect of these landscape mosaics on arthropod diversity at local spatial scales in temperate and tropical regions, but little is known about fragmentation effects in crop systems, such as the complex tropical traditional crop systems that maintain a high diversity of weeds and arthropods in low-Andean regions. To understand the factors that influence patterns of diversity in human-dominated landscapes, we investigate the effect of land use types on plant and arthropod diversity in traditionally managed cornfields, via surveys of plants and arthropods in twelve traditional cornfields in the Colombian Andes. We estimated alpha and beta diversity to analyze changes in diversity related to land uses within a radius of 100 m to 1 km around each cornfield. We observed that forests influenced alpha diversity of plants, but not of arthropods. Agricultural lands had a positive relationship with plants and herbivores, but a negative relationship with predators. Pastures positively influenced the diversity of plants and arthropods. In addition, forest cover seemed to influence changes in plant species composition and species turnover of herbivore communities among cornfields. The dominant plant species varied among fields, resulting in high differentiation of plant communities. Predator communities also exhibited high turnover among cornfields, but differences in composition arose mainly among rare species. The crop system evaluated in this study represents a widespread situation in the tropics, therefore, our results can be of broad significance. Our findings suggest that traditional agriculture may not homogenize biological communities, but instead could maintain the regional pool of species through high beta diversity.

In this study occurrence, proportion and landscape pattern of grasslands and wastelands are analysed in Külső-Somogy based on MÉTA method at landscape scale. The relative importance of these habitat types represent more than the half of the total number of non-woody habitats listed for Hungary. Wastelands (62%) and disturbed grasslands (54%) have relatively the greatest area in this region, where uncharacteristic dry or semi-dry grasslands and tall herb communities dominate. Semi-natural dry and semi-dry grassland habitat types are in subordinated position in the southern and eastern parts of the region, especially with habitats of E-group, H-group or uncharacteristic herb communities (OC). As semi-natural non-woody wet grasslands types habitats of B-group are the relatively most frequent with eu- and mesotrophic reed and Typha beds, nontussock beds of large sedges and mosaics of marsh communities of channels, ditches and artificial lakes. In landscape elements which are poor in grasslands uncharacteristic wet or dry grass habitats (O-group) are significant. The north-western parts of Külső-Somogy near Lake Balaton are strongly endangered by the reduction or lack of semi-natural grasslands. Regional land and grassland management ought to promote functioning of grassland regeneration processes.

Question: Are changes in plant species composition, functional group composition and rates of species turnover consistent among early successional wetlands, and what is the role of landscape context in determining the rate of succession?Location: Twenty‐four restored wetlands in Illinois, USA.Methods: We use 4 years of vegetation sampling data from each site to describe successional trends and rates of species turnover in wetlands. We quantify: (1) the rate at which composition changes from early‐successional to late‐successional species and functional groups, as indicated by site movement in ordination space over time, and (2) the rate of change in the colonization and local extinction of individual species. We correlate the pace of succession to site area, isolation and surrounding land cover.Results: Some commonalities in successional trends were evident among sites. Annual species were replaced by clonal perennials, and colonization rates declined over time. However, differences among sites outweighed site age in determining species composition, and the pace of succession was influenced by a site's landscape setting. Rates of species turnover were higher in smaller wetlands. In addition, wetlands in agricultural landscapes underwent succession more rapidly, as indicated by a rapid increase in dominance by late‐successional plants.Conclusions: Although the outcome of plant community succession in restored wetlands was somewhat predictable, species composition and the pace of succession varied among sites. The ability of restoration practitioners to accelerate succession through active manipulation may be contingent upon landscape context.

Sheep can have an important role in the conservation of abandoned and shrub- and tree-encroached, semi-natural dry grasslands because their feeding behaviour is known to affect plant diversity and structure. Nevertheless, little information is available about feeding preferences of sheep at the sward-patch scale and about the effects of stocking density on their selectivity. Consequently, we investigated plant-species selection by sheep managed with a low-intensity grazing, examining the influence of stocking density and plant species abundance by means of vegetation surveys and animal GPS tracking. Sheep grazed a graminoid-dominated, semi-natural dry grassland (Festuco–Brometea) in Piedmont Region, north-west Italy. Plant species, classified into graminoids, suffruticose forbs, and herbaceous forbs, were selected with a different intensity by sheep, which preferred graminoids over suffruticose and herbaceous forbs. Plant species showing a high consumption ratio (CR), i.e. the level of selection of plant species (CR >10%), were mostly graminoids (e.g. Bromus erectus, Koeleria vallesiana and Stipa pennata). Furthermore, Carex species were also noticeably selected, in particular C. humilis, whereas spiny species and those with a rosette or prostrate forms were rarely grazed. The heterogeneity of stocking density over the pasture allowed testing of the relationships between stocking density and CR. For many species, the higher the stocking density, the higher was the CR, regardless of the abundance of dominant neighbouring species. Results suggest that sheep under low-intensity grazing conditions exert a specific plant-species selection in abandoned dry grasslands. By regulating the stocking density through the management of grazing sheep, it may be possible to condition the consumption of certain plant species, with medium–long-term effects on the botanical composition.

Agricultural intensification has resulted in severe declines in the extent and diversity of seminatural habitats in Europe, whereas the extent of secondary habitats has increased considerably. River embankments have become one of the most extensive and widespread secondary habitats in former floodplains. We compared the diversity patterns of secondary dry and wet grasslands on river embankments with those of seminatural dry and wet grasslands in a Hungarian agricultural landscape using the following community descriptors: (a) species diversity, (b) phylogenetic diversity and (c) functional diversity. We also performed trait‐based analyses to evaluate the ecosystem services provided by these secondary grasslands. Both grassland types of the embankments showed significantly higher Shannon diversity compared with their seminatural counterparts. The cover of generalist species (i.e., cosmopolitan species, weeds and nonindigenous plant species) was high in the secondary grasslands. We found significant differences in phylogenetic diversity between the secondary and seminatural grasslands: secondary grasslands showed significantly lower mean nearest taxon distances than the seminatural grasslands. Functional diversity did not differ between the secondary and seminatural grasslands according to the Rao's quadratic entropy. However, we found higher community‐weighted means of specific leaf area, plant height and flowering period in the secondary grasslands, which are related to important ecosystem services (via biomass production and pollination). Well‐planned management actions and restoration activities could help further improve the ecological function and conservation value of secondary grasslands on river embankments, contributing to the maintenance of species diversity and sustaining the functionality of ecosystems in agricultural landscapes.