Monday, 11 January 2021

Recovery of extremely overgrazed grassland after grazing exclusion: New paper in Arid Land Research and Management

 Overgrazing causes serious problems in rangeland ecosystems and for human livelihoods worldwide, especially in the arid and semiarid regions. Too intense grazing, trampling and manuring have profound effects on vegetation composition, support the encroachment of weeds and leads to soil erosion. Sheep grazing gardens with fixed fence became increasingly popular and widespread in many parts of Europe, causing a rapid degradation of to the affected vegetation. In our recently published paper, we studied the vegetation of an experimental sheep grazing garden affected by extreme overgrazing (25 sheep per hectare) and evaluated the short-term vegetation recovery after grazing exlusion. The first author of the paper is Krisztina Varga, my former MSc student, who now works at the Karcag Research Institute of the University of Debrecen.

The citation of the paper is the following:

Varga, K., Csízi, I., Monori, I., Valkó, O. (2021): Threats and challenges related to grazing gardens: Recovery of extremely overgrazed grassland after grazing exclusion. Arid Land Research and Management doi: 10.1080/15324982.2020.1869120

Abstract

Overgrazing causes serious problems for rangeland ecosystems and human livelihoods globally. Sheep grazing paddocks with fixed fences have become increasingly widespread in Europe; however, their effects on biodiversity have rarely been discussed. Our aim was to measure the degradation of grassland vegetation in an experimental sheep paddock in Central-Hungary, and evaluate recovery of alkali grasslands after the exclusion of grazing. We compared the vegetation of heavily overgrazed parcels to parcels excluded from overgrazing, treated with three doses of manure (0, 20 and 40t/ha), in the first three years of grassland recovery. The overgrazed parcels were dominated by nutrient-demanding ruderal plant species and the cover of target grassland species was only 19.8% in the third year. After grazing exclusion, the cover of target grassland species increased to 81.0% for Year 3. The dominant grass Festuca pseudovina became more abundant in the excluded parcels (51.1%) than in the overgrazed ones (8.9%). At the end of the experiment, the rate of degradation (0.2 vs. 3.7) and the cover-weighted ecological indicator values for nutrients (3.8 vs. 5.1) were significantly lower in the exclosures than in the overgrazed parcels. Manuring did not have a significant effect on grassland recovery; thus, it is not necessary in the studied ecosystem. We recommend avoiding grazing paddocks with fixed fence especially in areas harboring habitats of high conservation value. Besides resulting in the degradation of grasslands, grazing paddocks also act as landscape scars and propagule sources of problem species that might negatively affect the surrounding landscape.

Sheep grazing in alkali grasslands in the Hortobágy. Photo: Balázs Deák.

Monday, 4 January 2021

Linking environmental heterogeneity and plant diversity at intermediate scales - Our new paper in Science of the Total Environment


Our new paper about the link between environmental heterogeneity and plant diversity has recently been accepted in Science of the Total Environment.


Deák, B., Kovács, B., Rádai, Z., Apostolova, I., Kelemen, A., Kiss, R., Lukács, K., Palpurina, S., Sopotlieva, D., Báthori, F., Valkó, O. (2021): Linking environmental heterogeneity and plant diversity: the ecological role of small natural features in homogeneous landscapes. Science of the Total Environment 763: 144199 [IF2019: 6.551]

The paper is open access and can be downloaded by clicking here

Environmental heterogeneity (EH), encompasses spatial and temporal heterogeneity in biotic (land cover, vegetation) and abiotic (climate, soil and topography) components. EH is considered one of the most important drivers of species richness patterns from local to continental scales. The conservation importance of EH is being recognised globally, due to the generally positive relationships between EH and biodiversity. However, there are several open questions regarding EH-biodiversity relationships. Although the effects of EH components are often interrelated and all of them affect biodiversity patterns, most studies consider only one, or a few, of them. Moreover, studies generally focus either on a continental/landscape-scale or a fine-scale of a few centimetres/metres, but there are only a few studies concentrating on intermediate spatial scales.

The relationship between environmental heterogeneity and plant diversity is well known in mountain environments.

For establishing links between EH components and biodiversity at intermediate scales of a couple of metres, small natural features (SNFs) provide an outstanding opportunity. SNFs include field margins, road verges, midfield islets, stone walls, karst dolines, ancient earthworks and burial mounds, all of these can be regarded as distinct entities differing from their surroundings in their abiotic and biotic conditions, and they are often characterised by a high level of EH. These SNFs are characteristic elements in many landscapes, but little is known about the relationship between EH components and the associated biodiversity patterns found on them. For our study, we chose several millennia-old ancient burial mounds (built by nomadic steppe tribes), which are one of our favourite natural features. If you are particularly interested in these iconic landscape elements, please read our former blog post here.

Ancient burial mounds in Bulgaria - the most impressive ones can be as high as ten metres and they are covered by dry grasslands.

In this study, we focused on all components of EH that are potential drivers of vegetation patterns, and can contribute to the maintenance of grassland biodiversity on topographically heterogeneous SNFs. We surveyed ancient burial mounds covered by dry grasslands in the Pannonian (Hungary) and Continental (Bulgaria) biogeographical regions of Europe, in order to test whether the effects of EH on vegetation composition depends on the biogeographical region. In order to understand the interactions between EH components and reveal their effects on plant diversity and species composition, we studied the five main EH components on mounds using nearby plain grasslands as a reference. On each mound, we investigated five mound microsites (slopes with different main aspects and top).

Figure showing our sample design.

We found very interesting patterns in the microclimate parameters on the slopes of the mounds. The figure below shows that mound microsites were characterised by considerable fluctuations between extreme positive and negative relative values of air temperature (T), relative humidity (RH) and vapour pressure deficit (VPD). In the morning, the air of the east-facing slopes warms up faster than the plain grassland or the top, and becomes dry, while west-facing slopes remain cool and humid. In the afternoon, this pattern reverses, but west-facing slopes dry and warm up to a lesser degree. Diurnal variations are due to the temporal changes in solar radiation received by the different microsites. East-facing slopes warms up and consequently become drier earlier than plain grasslands and other mound microsites. It is very impressive that these patterns can be detected in landscape elements that are maximum 10 metres high!

Diurnal variations of air temperature (ΔT), relative humidity (ΔRH) and vapour pressure deficit (ΔVPD) in the studied mound microsites, relative to the values detected in plain grasslands (dotted line).

As shown by the diurnal variations, the difference between north- and south-facing slopes was greatest when the Sun is at the zenith (at about 13:00). At that time north-facing slopes were 5.1°C cooler and south-facing slopes 7.6°C warmer than plain grasslands. In the case of mounds occurring in regions with a generally harsh continental macro-climate, small-scale micro-topographical differences are equivalent to large latitudinal (several hundreds of kilometres) and elevation differences (the observed 12.7°C range in temperature within the small area of a mound is roughly equivalent to a shift of couple of hundred metres in altitude) over very short horizontal distances. The microclimatic differentiation detected on the mounds in our study highlights the importance of small landforms in plain areas that can introduce a high level of EH to the otherwise homogeneous landscape.

North-facing slope of a mound in Bulgaria covered by Elymus elongatus and Ranunculus illyricus.

We found that the different abiotic environmental conditions represented by microsites were reflected in the vegetation patterns; thus, the microsites studied function as microhabitats for plant species. On the site level we detected clear patterns in both regions; the vegetation composition of mild and harsh mound microhabitats and the grassland were well-separated in all the sixteen sites.

Ordination diagrams from the non-metric multidimensional scaling, displaying the species compositions of the studied microsites (HU – Hungary; BG – Bulgaria). Large panels show the patterns on the regional level (points with the same colour denote the average of five plots per microsite per site), whilst small panels show the species composition of different microsites on the site level (one point represents one plot).

In general, the mild north- and west-facing slopes had similar species composition, dominated by specialists such as Elymus hispidus, Stipa capillata, Inula germanica, Helianthemum salicifolium, and Inula oculus-christi, and only a few species indicating degradation. The harsh south-facing slopes and the top shared similar species composition, harbouring stress- and disturbance-tolerant generalists and weeds (e.g. Elymus repens, Bromus spp., Senecio vernalis). The varying but harsh east-facing slopes showed a scattered pattern. Plain grasslands were characterised by a rather distinct species pool in both regions.

Our findings highlight that SNFs have a crucial conservation importance in plain landscapes, which cover one third of the global land area. We found that even landforms, which are only a few metres high, can introduce a large variation of environmental heterogeneity into these areas. Besides the more than half a million Eurasian mounds, there are also many analogous and globally widespread landforms (inselbergs, dolines, mounds built by ecosystem engineering rodents) that can have a similar function in introducing EH to environmentally homogeneous landscapes, and therefore driving local and landscape-scale diversity patterns within these landscapes.

Graphical abstract summarising the key findings of the paper.

Abstract

Small natural features (SNFs), such as road verges, midfield islets, rocky outcrops and ancient burial mounds, provide safe havens for species of natural habitats in human-modified landscapes; therefore, their great ecological importance is in contrast to their small size. SNFs often have a high topographical heterogeneity and abiotic conditions, which differ from their surroundings; therefore, they provide a unique opportunity for establishing links between environmental heterogeneity (EH) and biodiversity. However, no study has so far investigated the EH components of topographically heterogeneous SNFs in a comprehensive framework, by linking environmental and biotic parameters. To fill this knowledge gap, we evaluated the EH components and their effect on biodiversity on ancient mounds covered by semi-natural grasslands in the Pannonian (Hungary) and Continental (Bulgaria) biogeographical regions. We designated 16 study sites, each containing a few-metre-high mounds with five microsites (top, north-, east-, south- and west-facing slopes) and a nearby plain grassland. At each microsite, we measured soil moisture, soil chemical properties, solar radiation and microclimate; and recorded the cover of vascular plants in a total of 480 plots. On the mounds, topographical heterogeneity was associated with sharp differences in microclimate and soil properties. Besides the contrast between mild north-facing and harsh south-facing slopes, east- and west-facing slopes also sustained unique microsites characterised by dynamic diurnal changes in air temperature and vapour pressure deficit. Various combinations of the EH components resulted in unique plant species compositions within the microsites, and supported the co-occurrence of species typical of contrasting habitat types, even within a couple of metres. By combining high-resolution measurements of abiotic factors with fine-scale vegetation sampling, our study provides evidence that widespread SNFs with complex topography harbour several grassland-specialist plant species and introduce a high level of EH to otherwise homogeneous plain landscapes, which cover one third of the global land area.

Group photo in our expedition in Bulgaria; from left to right: Salza Palpurina, Iva Apostolova, Desislava Sopotlieva, Réka Kiss, Katalin Lukács, András Kelemen, Orsolya Valkó, Balázs Deák.


Wednesday, 2 December 2020

Soil Science Challenges in a New Era: A Transdisciplinary Overview of Relevant Topics

 

Our review paper by Jesús Rodrigo-Comino et al. entitled 'Soil Science Challenges in a New Era: A Transdisciplinary Overview of Relevant Topics' has been published in the journal Air, Soil and Water Research. We give an overview on the prospects, challenges, technological advances and hot topics of soil science. The paper was written by the editorial board of the journal, and the twenty authors from various disciplines offer perspectives on research directions.

Citation

Rodrigo-Comino, J., López-Vicente, M., Kumar, V., Rodríguez-Seijo, A., Valkó, O., Rojas, C., Pourghasemi, H.R., Salvati, L., Bakr, N., Vaudour, E., Brevik, E.C., Radziemska, M., Pulido, M., Di Prima, S., Dondini, M., de Vries, W., Santos, E.S., Mendonça-Santos, M. de L., Yu, Y., Panagos, P., 2020. Soil Science Challenges in a New Era: A Transdisciplinary Overview of Relevant Topics. Air, Soil and Water Research 13: 1178622120977491. doi: 10.1177/1178622120977491

The paper is open access and it is freely accessible by, clicking here.

Abstract

Transdisciplinary approaches that provide holistic views are essential to properly understand soil processes and the importance of soil to society and will be crucial in the future to integrate distinct disciplines into soil studies. A myriad of challenges faces soil science at the beginning of the 2020s. The main aim of this overview is to assess past achievements and current challenges regarding soil threats such as ero-sion and soil contamination related to different United Nations sustainable development goals (SDGs) including (1) sustainable food production, (2) ensure healthy lives and reduce environmental risks (SDG3), (3) ensure water availability (SDG6), and (4) enhanced soil carbon sequestration because of climate change (SDG13). Twenty experts from different disciplines related to soil sciences offer perspectives on important research directions. Special attention must be paid to some concerns such as (1) effective soil conservation strategies; (2) new computational technologies, models, and in situ measurements that will bring new insights to in-soil process at spatiotemporal scales, their relationships, dynamics, and thresholds; (3) impacts of human activities, wildfires, and climate change on soil microorganisms and thereby on biogeochemical cycles and water relationships; (4) microplastics as a new potential pollutant; (5) the development of green technologies for soil rehabilitation; and (6) the reduction of greenhouse gas emissions by simultaneous soil carbon sequestration and reduction in nitrous oxide emission. Manuscripts on topics such as these are particularly welcomed in Air, Soil and Water Research

Tuesday, 10 November 2020

Recovery of Mediterranean grasslands: New paper in Tuexenia

Our paper about the role of livestock grazing in the recovery of Mediterranean grasslands has recently been published in Tuexenia. We are happy that we could work together with our friend Rocco Labadessa on this interesting topic.

Citation

Labadessa, R., Deák, B., Valkó, O. (2020): No need for grazing exclusion – Sheep grazing supports the recovery of grasslands even from the early successional stages. Tuexenia 40: 429-443.

The paper can be downloaded from here.

Abstract

Availability and dispersal of target plant propagules and applied management techniques can considerably affect the success of grassland restoration. In our study we explored the effect of sheep grazing on plant species composition of an early staged recovering grassland, which developed on newly created soil surfaces. We recorded the presence and cover of vascular plant species in 17 grazed and 6 ungrazed plots during three consecutive years after the restoration of a landfill in southern Italy. A DCA ordination based on species percentage cover was calculated to assess the species composition of the plots in the three years. Plant assemblages were compared to adjacent reference grassland in terms of species composition and cover of functional groups based on their role (i.e. target species or weeds) and their seed dispersal potential (i.e. high or low epizoochorous ranking index). For each parameter, Relative Response Indices (RRIs) were calculated to assess the relationship between the vegetation characteristics of the restored areas and the reference grassland. The DCA ordination of plant communities in the restored area revealed gradients of increasing similarity to reference grassland as a function of successional age and grazing. For most of the considered vegetation characteristics, RRIs in restored grassland became more similar to the reference grassland with increasing successional age and under grazed conditions. Besides underlining the role of passive restoration in supporting effective grassland recovery, our results revealed that extensive sheep grazing even from the early successional stages can improve target species dispersal and establishment, and enhance grassland restoration. Our results suggest that grazing can improve the feasibility and sustainability of restoration projects by saving costs of fence installation and providing forage for local animal husbandry.

Unfortunately many years have passed since we last met Rocco. This picture was taken in Hortobágy, in a nice excursion, many years ago.

 

 

Wednesday, 4 November 2020

New paper in Basic and Applied Ecology: Acceptance of near-natural greenspace management relates to ecological and socio-cultural assigned values among European urbanites


The second paper yielding from the European urban questionnaire survey has been published in Basic and Applied Ecology, by Jussi Lampinen et al. Many thanks to Jussi Lampinen, Valentin Klaus, Leonie Fischer, Lena Neuenkamp and all the colleagues for this wonderful paper!

Lampinen, J., Tuomi, M., Fischer, L.K., Neuenkamp L., Alday, J.G., Casado-Arzuaga, I., Čeplová, N., Deák, B., Eriksson, O., Escriche, A.M., Fellowes, M.D.E., Fernández De Manuel, B., Filibeck, G., González-Guzmán, A., Hinojosa, M.B., Kowarik, I., Lampei Bucharová, A., Lumbierres, B., Pardo i Martín, R., Pons, X., Rodríguez-García, E., Schröder, R., Tatay, L.C., Unterweger, P., Valkó, O., Vázquez Manzanares, V.M., Klaus, V.H. (2020): Acceptance of near-natural greenspace management relates to ecological and socio-cultural assigned values among European urbanites. Basic and Applied Ecology (in press) [IF2019: 3.156]

The final paper will be soon available in the Journal webpage, until then, you can access the pre-proof version from here.

Urban greenspaces are important places for people living in cities, as these places provide our everyday contact with nature. In this European-scale study we were interested whether urban citizens accept near-natural greenspace managements, and what ecological and socio-cultural values are assinged to them accross Europe.

Abstract

Grasslands are widespread elements of urban greenspace providing recreational, psychological and aesthetic benefits to city residents. Two urban grassland types of contrasting management dominate urban greenspaces: frequently mown, species-poor short-cut lawns and less intensively managed, near-natural tall-grass meadows. The higher conservation value of tall-grass meadows makes management interventions such as converting short-cut lawns into tall-grass meadows a promising tool for urban biodiversity conservation. The societal success of such interventions, however, depends on identifying the values urban residents assign to different types of urban grasslands, and how these values translate to attitudes towards greenspace management. Using 2027 questionnaires across 19 European cities, we identify the assigned values that correlate with people's personal greenspace use and their preferences for different types of urban grasslands to determine how these values relate to the agreement with a scenario of converting 50% of their cities’ short-cut lawns into tall-grass meadows. We found that most people assigned nature-related values, such as wildness, to tall-grass meadows and utility-related values, such as recreation, to short-cut lawns. Positive value associations of wildness and species richness with tall-grass meadows, and social and nature-related greenspace activities, positively correlated with agreeing to convert short-cut lawns into tall-grass meadows. Conversely, disapproval of lawn conversion correlated with positive value associations of cleanliness and recreation potential with short-cut lawns. Here, people using greenspaces for nature-related activities were outstandingly positive about lawn conversion. The results show that the plurality of values assigned to different types of urban grasslands should be considered in urban greenspace planning. For example, tall-grass meadows could be managed to also accommodate the values associated with short-cut lawns, such as tidiness and recreation potential, to support their societal acceptance.
 
The two main types of urban grasslands: tall-grass meadows and short-cut lawns.

 


Friday, 30 October 2020

Biodiversity of fragmented dry grasslands - Our new paper in Biodiversity and Conservation


In our new paper, recently published in Biodiversity and Conservation, we compared the species and phylogenetic diversity of patch-like and linear fragmented dry grasslands in agricultural landscapes.

The paper is freely available in the journal's homepage; please click here to download.

Deák, B., Rádai, Z., Lukács, K., Kelemen, A., Kiss, R., Báthori, Z., Kiss, P.J., Valkó, O. (2020): Fragmented dry grasslands preserve unique components of species and phylogenetic diversity in agricultural landscapes. Biodiversity and Conservation doi: 10.1007/s10531-020-02066-7 

Abstract

In intensively used landscapes biodiversity is often restricted to fragmented habitats. Exploring the biodiversity potential of habitat fragments is essential in order to reveal their complementary role in maintaining landscape-scale biodiversity. We investigated the conservation potential of dry grassland fragments in the Great Hungarian Plain, i.e. patch-like habitats on ancient burial mounds and linear-shaped habitats in verges, and compared them to continuous grasslands. We focused on plant taxonomic diversity, species richness of specialists, generalists and weeds, and the phylogenetic diversity conserved in the habitats. Verges meshing the landscape are characterised by a small core area and high level of disturbance. Their species pool was more similar to grasslands than mounds due to the lack of dispersal limitations. They held high species richness of weeds and generalists and only few specialists. Verges preserved only a small proportion of the evolutionary history of specialists, which were evenly distributed between the clades. Isolated mounds are characterised by a small area, a high level of environmental heterogeneity, and a low level of disturbance. Steep slopes of species accumulation curves suggest that high environmental heterogeneity likely contributes to the high species richness of specialists on mounds. Mounds preserved the same amount of phylogenetic diversity represented by the branch-lengths as grasslands. Abundance-weighted evolutionary distinctiveness of specialists was more clustered in these habitats due to the special habitat conditions. For the protection of specialists in transformed landscapes it is essential to focus efforts on preserving both patch-like and linear grassland fragments containing additional components of biodiversity.

Species rich grassland vegetation on the Erdő-mound


The verges of roads and railroads can provide safe havens for grassland species
even in transformed landscapes

Saturday, 24 October 2020

Kurgan restoration - a pilot project in the Hortobágy National Park

Involvement of kurgans into the system of agricultural subsidies was an important step forward in preserving these iconic landscape elements. According to the regulations, in Hungary, farmers are not allowed to plough the kurgans (although it was typical case in the past), but they can consider the area of the kurgans as a part of the ecological focus areas (which result in an increase in the received subsidies). This construction can support the preservation of the structure of the kurgans in the whole country. However, for restoring grassland habitats on kurgans and improve their important role as significant landscape elements further active measures are needed. In the case of formerly ploughed kurgans this step is the restoration of dry grassland habitats on kurgans. Restored grassland vegetation can mitigate the populations of weed species on the abandoned kurgans and by active plant introduction also several grassland species can be established on the kurgans with a relatively low cost. Reduction of weeds can increase the landscape value of the kurgans and also profitable for the farmers as the suppression of weeds on the kurgan also decreases the amount of weeds in the neighbouring crops. The established grassland species can increase the landscape-scale biodiversity, and the restored grassland patches can be essential elements of the landscape-scale network of semi-natural habitats.

Our research group together with the colleagues from the Hortobágy National Park Directorate aimed to restore the grassland vegetation of two kurgans (Hegyes and Kishegyes mounds) near the settlement of Püspökladány. You can read about our former similar project here.

The sown grassland of the Hegyes mound; in the distance the smaller Kishegyes mound.

After the cessation of ploughing, both kurgans were sown by Festuca pseudovina which resulted in a closed grass cover on the kurgans hindering weed encroachment. Since the kurgans were quite a distance from the neighbouring natural grasslands, the spontaneous immigration of grassland plants to the kurgans was very slow. That is why in this year we applied active seed sowing to support this process. We sowed the seeds typical to local loess grasslands (Agropyron cristatum, Salvia austriaca, S. nemorosa, Filipendula vulgaris, Phlomis tuberosa and Dianthus pontederae) in small open patches (you can see our related post about the application of establishment gaps in sown grasslands here). For this we used the soil disturbances by small mammals and foxes, which due to their burrowing activity opened the otherwise closed grassland "mat" and prepared small scale soil disturbances. (You can read our paper about the effect of fox burrows on the populations of grassland species on kurgans here). Agropyron cristatum was sown on the top of the mounds, since in natural conditions this species often forms monodominant patches in this micro-habitat. The forb species were sown as a seed mixture into the open patches on the slopes. We hope that these species can establish successfully in the establishment gaps, and later they can be abundant on the kurgans. To support this process, an extensive grazing system will be introduced on the kurgans: in autumn, after the crop is harvested the mounds will be managed by cattle grazing.

  

A short meeting before we started to work.



Preparation of establishment windows (1).

Preparation of establishment windows (2).


Seed mixture (1).

Seed mixture (2).


Hand sowing (1).

Hand sowing (2).


Sown seeds of Agropyron cristatum.

After the sowing we used raking to provide a shallow soil cover for the sown species.


The team (from left to the right: Orsolya Valkó, Balázs Deák, Károly Hoffmann, Katalin Lukács and Réka Kiss).

Migrating cranes above the Hegyes mound.