Early spring fieldwork - Effects of soil perturbation by cranes on grassland vegetation

Common cranes (Grus grus) are large body-sized migratory birds. They breed in Northern Europe and during their migration, the open landscape of Hortobágy (East-Hungary) are a very important stopover site. In autumn, crane migration is a spectacular event (see a former post about it here). Thanks to the conservation efforts, the number of cranes visiting the Hortobágy National Park is increasing, and in the autumn of 2019 their estimated number was approximately 160,000. 

Related to the research plan of the Lendület Seed Ecology Research Group, and being part of the PhD project of Sándor Borza, we are interested in the effect of the large flocks of these migratory birds on the vegetation dynamics of alkaline grasslands. During foraging, cranes create distinct and unique vegetation patches by severe soil disturbance with their bill - this soil disturbance can be sometimes so severe that it resembles ploughing. That is why the Hungarian term for this spectacular phenomenon is 'crane-ploughing'. Our aim is to study the vegetation composition of the crane perturbations in comparison to undisturbed soil surfaces throughout the large pristine alkaline grasslands of the Hortobágy. 

We completed the early spring fieldwork a few days ago and below we share a few nice pictures about it.

Large grassland areas 'ploughed' by the cranes in Angyalháza. Photo by Sándor Borza.

One of our sampling plots in a crane-ploughing. Photo by Sándor Borza.

Vegetation sampling in the crane-ploughed area. Photo by Sándor Borza.

A less severely ploughed area. Photo by Laura Godó.

Erophila verna is an early spring annual species which is sometimes the dominant species of the crane perturbations. Photo by Laura Godó.

Crane feather on the crane-ploughing :) Photo by Laura Godó.

The perturbed surfaces are characterised by annuals and forbs and a lot of mosses. Photo by Balázs Deák.

One of our sample sites near Nagyiván. Photo by Balázs Deák.

The fine-scale microtopography typical to alkaline landscapes is well visible in springtime. Photo by Balázs Deák.

Woody species desiccate deep soil layers in sandy drylands - Our new paper in Ecography

Our new paper about the role of woody species in landscape-scale soil water balance in sandy drylands has recently been published in Ecography.

The main authors are Csaba Tölgyesi and András Kelemen, whose idea was to test the environmental effects of woody species in water-limited ecosystems in a multi-scale framework. We found that the aboveground islands of fertility are underground deserts: forest plantations in sandy drylands can accelerate the effects of desertification. Based on our results we highlight the need for a more sophisticated and careful attitude towards afforestation in arid ecosystems.

Tölgyesi, C., Török, P., Hábenczyus, A.A., Bátori, Z., Valkó, O., Deák, B., Tóthmérész, B., Erdős, L., Kelemen, A. (2020): Underground deserts below fertility islands? – Woody species desiccate lower soil layers in sandy drylands. Ecography doi: 10.1111/ecog.04906

Thanks for the main authors for their hard work! We are very happy that members our research group (underlined) could take part in this interesting study which is very important for conservation planning.

The paper is open access, please click here to download.

Abstract

Woody plants in water-limited ecosystems affect their environment on multiple scales: locally, natural stands can create islands of fertility for herb layer communities com-pared to open habitats, but afforestation has been shown to negatively affect regional water balance and productivity. Despite these contrasting observations, no coherent multi-scale framework has been developed for the environmental effects of woody plants in water-limited ecosystems. To link local and regional effects of woody species in a spatially explicit model, we simultaneously measured site conditions (microclimate, nutrient availability and topsoil moisture) and conditions of regional relevance (deeper soil moisture), in forests with different canopy types (long, intermediate and short annual lifetime) and adjacent grasslands in sandy drylands. All types of forests ameliorated site conditions compared to adjacent grasslands, although natural stands did so more effectively than managed ones. At the same time, all forests desiccated deeper soil layers during the vegetation period, and the longer the canopy lifetime, the more severe the desiccation in summer and more delayed the recharge after the active period of the canopy. We conclude that the site-scale environmental amelioration brought about by woody species is bound to co-occur with the desiccation of deeper soil layers, leading to deficient ground water recharge. This means that the cost of creating islands of fertility for sensitive herb layer organisms is an inevitable negative impact on regional water balance. The canopy type or management intensity of the forests affects the magnitude but not the direction of these effects. The outlined framework of the effects of woody species should be considered for the conservation, restoration or profit-oriented use of forests as well as in forest-based carbon sequestration and soil erosion control projects in water-limited ecosystems.

Finally, some photos about fieldwork - sampling throughout the whole year

Here is the spring - the field season has just started

This year, the spring came very early in Hungary. Now this is the time for seed bank sampling. In these weeks we are on an extensive field sampling campaign in Central Hungary, in the Kiskunság National Park.

Scenic road in Kunpeszér.

The ground squirrels (Spermophilus citellus) are already active in Bugac puszta.

Scenic landscape characterised by sand dunes in Pirtó, South-Hungary.

Preparation for the seed bank sampling.

Sample processing.

Seed bank sampling in wetlands in Kunpeszér.

Wetlands in Kunpeszér.

 

Sometimes you get muddy.

Like this.

and this :)

But this is still fun :)

New paper about Holocene fire dynamics in Central- and Eastern Europe

Our new paper about Holocene fire dynamics in relation to land cover, land use and climate dynamics in temperate and boreo-nemoral regions of Central- and Eastern Europe has been published in Biogeosciences.

An international team, lead by Angelica Feurdean collected an extensive dataset of Holocene pollen and sedimentary charcoal records across three ecoregions (Atlantic, continental, boreo-nemoral).

The citation of the paper is as follows

Feurdean, A., Vannière, B., Finsinger, W., Warren, D., Connor, S.C., Liakka, J., Panait, A., Andrič, M., Bobek, P., Carter, V.A., Davis, B., Diaconu, A.C., Dietze, E., Feeser, I., Florescu, G., Forrest, M., Gałka, M., Giesecke, T., Jahns, J., Jamrichová, E., Kajukało, K., Kaplan, J., Karpińska-Kołaczek, M., Kołaczek, P., Kuneš, P., Kupriyanov, D., Lamentowicz, M., Lemmen, C., Magyari, E.K., Marcisz, K., Marinova, E., Niamir, A., Novenko, E., Obremska, M., Pędziszewska, A., Pfeiffer, M., Poska, A., Rösch, M., Słowiński, M., Stančikaitė, M., Szal, M., Święta-Musznicka, J., Tanţău, I., Theuerkauf, M., Tonkov, S., Veski, S., Valkó, O., Vassiljev, J., Vincze, I., Wacnik, A., Werner, C., Wiethold, J., Hickler, T. (2020): Fire risk modulation by long-term dynamics in land cover and dominant forest type in Eastern and Central Europe. Biogeosciences 17: 1213-1230. doi: 10.5194/bg-2019-260

The paper is open access and can be downloaded here.

Abstract

Wildfire occurrence is influenced by climate, vegetation and human activities. A key challenge for understanding the risk of fires is quantifying the mediating effect of vegetation on fire regimes. Here, we explore the relative importance of Holocene land cover, land use, dominant functional forest type, and climate dynamics on biomass burning in temperate and boreo-nemoral regions of central and eastern Europe over the past 12 kyr. We used an extensive data set of Holocene pollen and sedimentary charcoal records, in combination with climate simulations and statistical modelling. Biomass burning was highest during the early Holocene and lowest during the mid-Holocene in all Three ecoregions (Atlantic, continental and boreo-nemoral) but was more spatially variable over the past 3–4 kyr. Although climate explained a significant variance in biomass burning during the early Holocene, tree cover was consistently the highest predictor of past biomass burning over the past 8 kyr. In temperate forests, biomass burning was high at 45% tree cover and decreased to a minimum at between 60% and 70% tree cover. In needleleaf-dominated forests, biomass burning was highest at 60 %–65%tree cover and steeply declined at > 65% tree cover. Biomass burning also increased when arable lands and grasslands reached 15 %–20 %, although this relationship was variable depending on land use practice via ignition sources, fuel type and quantities. Higher tree cover reduced the amount of solar radiation reaching the forest floor and could provide moister, more wind-protected microclimates underneath canopies, thereby decreasing fuel flammability. Tree cover at which biomass burning increased appears to be driven by warmer and drier summer conditions during the early Holocene and by increasing human influence on land cover during the late Holocene. We suggest that longterm fire hazard may be effectively reduced through land cover management, given that land cover has controlled fire regimes under the dynamic climates of the Holocene.

New paper on terrestrial cyanobacteria - an interesting biocrust in alkaline grasslands

Our paper about terrestrial cyanobacteria has recently been published in Algal Research. The main authors of the paper are Milán Riba, Gábor Vasas and their colleagues who explored the peptide metabolite patterns of Nostoc-like strains.

The citation of the paper is

Riba, M., Kiss, A., Gonda, S., Parizsa, P., Deák, B., Török, P., Valkó, O., Vasas, G. (2020): Chemotyping of terrestrial Nostoc-like isolates from alkali grassland areas by non-targeted peptide analysis. Algal Research 46: 101798. doi: 10.1016/j.algal.2020.101798 [IF2018: 3.723]

Please click here to download the paper. 

Why are Nostoc species important? Nostoc is a genus of nitrogen-fixing cyanobacteria. They play a role in the maintenance of soil fertility and are used as green manure in many countries. In tropical and subtropical regions, mass presence of Nostoc species is typical in flooded rice paddies. They significantly increase soil fertility and rice yields. Nostoc species are one of the most common photosynthetic partners in symbiotic interactions; symbiotic Nostoc strains can occur in liverwort, hornwort, ferns, cycads, angiosperms and lichens.

Nostoc biocrust (black formations) in an open alkaline grassland.

The reason why we are particularly interested in Nostoc is that they form biocrust in continental alkaline grasslands. In Europe, these habitats cover approx. 200 000 ha, which is almost entirely (>98%) located in Hungary. Alkaline habitats are included in the Natura 2000 network as habitats of special community interest (*1530, Pannonic salt steppes and marshes). Colonies of Nostoc species appear at the beginning of spring, when the soil surface is flooded with water. Swollen colonies form mucous layers which then dry out during summer. In our former paper (Sonkoly et al. 2017) we tested the effect of Nostoc on the germination of plant of alkaline grasslands. We used field-collected Nostoc colonies to prepare a cell-free water extract, and treatments (watering with Nostoc extract and watering with tap water) were tested seeds of nine alkaline grassland species. Our results suggest that the presence of Nostoc colonies might affect the establishment of grassland species. We found that the effect of the Nostoc extract was species-specific, which suggests that Nostoc species may be an indirect driver of the interspecific competition between grassland plants.

The recently published Riba et al. (2020) paper takes a new step towards the better understanding of the diversity of Nostoc, important biocrusts of alkaline grasslands. We demonstrated the peptide metabolite-producing ability of terrestrial nitrogen-fixing cyanobacteria from different sites of the alkaline habitats of Hungary. The isolated Nostoc-like strains could be classified into different chemotype groups based on their metabolic pattern. A total of 41 peptide-type metabolites were identified which belonged to 4 different peptide families.

Open alkaline swards are typical habitats of Nostoc.