Subproject 600

SP 600 - Carbon stocks and biodiversity values in non-arable ecosystems

Introduction - Objectives - Methods - First Results

Introduction

The extensive peatlands of the West-Siberian lowland comprise carbon stocks of global relevance and act as an important sink in the global carbon balance. In the course of predicted global warming and changes in land-use, these carbon stocks run the risk of altering into a huge source of carbon with a feedback on global warming processes. Across the pre-taiga and forest steppes of Western Siberian, mire ecosystems are alternated with arable land on fertile Chernozem soils and forests on dry sandy substrates. Wet and peaty soils are only partly used for arable agriculture due to considerable effort needed to drain them and more easily manageable land still left. They are either untouched or extensively used as meadows and pastures. Apart from their role as carbon sinks and functions for water retention, these natural and semi-natural ecosystems are of outstanding importance for biodiversity conservation. However, especially in the vicinity of the city of Tyumen already large areas have been drained during Sovjet times and are often used as species poor sown grasslands even where yields are low.
Extensive sedge fens, natural river floodplains and ecotonal forest-steppe ecosystems consisting of open meadow-steppe grasslands and hemi-boreal forests belong to the most valuable habitats that harbour a variety of highly specialized flora and fauna including even globally threatened species such as Greater Spotted Eagle, Pallid Harrier and Aquatic Warbler These valuable ecosystems are supposed to react very sensitive in case of environmental changes such as global warming and intensification of land use. Arable expansion will lead to direct losses of grasslands and other habitats through land reclamation and will negatively impact neighbouring areas through drainage and increased nutrient input. A negative impact of an intensification of arable land use is likely, but hard to predict. 

Objectives

• Analysis of current abiotic and biotic functions of non-arable ecosystems
• Development of indicator systems for the evaluation of the current status and as a baseline for an assessment of future change
• Up-scaling of biotic and abiotic plot data to the landscape level
• Provision of baseline data for the modelling of future scenarios of landscape change
• Definition of priority areas for conservation and recommendations for sustainable land-use practices in the course of the planning and implementation process

Methods

Based on land-cover and land-use analysis of the three test areas (see SP200) , types of non-arable ecosystems are defined and used for the development of a stratified sampling design (Fig. 1). According to its surface area, 25 sampling plots in hemi-boreal birch forests and 50 sampling plots in grasslands were randomly chosen in each of the three test areas. For the assessment of carbon stocks and abiotic site conditions soil cores are taken and analyzed in the lab for various parameters including C, N, P, K and spectral properties (FT-IR Spectra). Further laboratory work includes analyzing a ¹⁴C-dated peat core which was provided by our Russian partners and will be analysed for 13C, 34S, FT-IR spectra and testate amoebae communities. This will provide us insights into the past climatic conditions that promoted peat bog growth and give us additional information about the carbon cycle on local scale.Vegetation relevés are made for each of the sampling plots. Plot size for ground vegetation is 100 m². In forest ecosystems the shrub and tree layer is recorded on an area of 500 m². Each vegetation record includes a complete list of vascular plants. To assess biodiversity productivity relationships, aboveground biomass of grassland sampling spots is sampled and analyzed for its chemical composition in the lab. Existing data on flora and vegetation are compiled and analyzed together with our Russian partners. Floristic and environmental plot data are used to develop a system of indicator species and species groups that can be used for the evaluation of site conditions and change detection.

Fig. 1: Sampling design and sample plots in all three study areas

To evaluate faunal biodiversity representatively we chose model groups that cover the range of trophic levels from predators to herbivores and of mobility from good to poor dispersers. We use birds, grasshoppers and butterflies as model organisms. Bird surveys have been carried out more than 400 standardized line transects using Distance Sampling. Each transect is about 500m long and is repeated twice. Grasshoppers have been sampled using box quadrates. Butterflies have been counted visually along Pollard transects. Similarly to the floristic diversity the faunal data are used to elaborate a system of indicator species (groups).

Fig. 2: Species-rich meadow steppe (photo: Wanja Mathar)

First Results

During the two field campaigns in the years 2012 and 2013, sampling of vegetation and soil in grasslands and birch forests was largely completed in all three test areas. In the field season in 2013 first surveys were conducted in the large bogs north of the city of Tyumen. The survey of grasshoppers and butterflies has already been performed in the test areas at Ishim and Omutinsk and will be completed by 2014 with the field work in the test area Kaskara. After the survey of bird communities on arable and fallow land as well as pastures and hay meadows in the test areas Kaskara and Ishim, forests and mosaic landscapes were also sampled in 2013. For 2014, surveys of intact and degraded fens in the region are planned.

The field campaigns in the years 2012 and 2013 resulted in the following preliminary results:

Vegetation and Fauna:

Forest-meadow complex

• Largest diversity of vascular plants, butterflies and birds in semi-natural areas in structurally rich forest-grassland complexes, agriculturally used areas are of rather little importance.

• The situation is different for grasshoppers of which we found comparable species-rich communities with reproduction on croplands.

Lesser Marbled Fritillary
(Brenthis ino)

• The abandonment of mown meadows and pastures has a major impact on the composition of the breeding bird and grasshopper communities and leads to declines in the diversity of plants and butterflies compared to flower-rich meadow steppe. Abandonment impacts on birds are diverse, with some species clearly benefitting.

• Since forests are kept open by frequent fire and grazing, butterfly and nesting bird communities benefit, with many species regularly recorded that have been declining across Europe. Open birch forests harboured the highest diversity of plants and many species that have become rare Central Europe.

Fen landscape north of Tyumen

• The transitional mires around Tyumen which evolved from classic lake succession represent ecosystems of outstanding biodiversity as they cover a wide range of trophic conditions. They harbour some bog-typical and boreal plant species which are highly endangered in Europe (e.g. Carex limosa, Scheuchzeria palustris, Rubus chameamorus).

• The role of these mires for carbon sequestration is enormous due to average peat depths of 4-5 m were recorded.

• First results of pore water sampling in one of those transitional mires also point towards their importance for the regional carbon cycle (results from gas measurements of CO₂ and CH4 in aqueous solution, Figure 6). These data will enable us to calculate production rates and fluxes and lead to a better understanding of their role for carbon fixation.

Fig. 6: Methane and CO₂-concentrations along a  sampling depth gradient, Tarman fen, Tyumen.

Contact

Contact

Prof. Dr. Norbert Hölzel
Westfälische Wilhems-Universität Münster
Institut für Landschaftsökologie
Heisenbergstraße 2
D-48149 Münster
Tel.: +49 (0) 251 83 33 994
Fax: +49 (0) 251 83 38 338
E-Mail: norbert.hoelzel@uni-muenster.de
Web: http://www.uni-muenster.de/Oekosystemforschung/

Prof. Dr. Hermann Mattes
Westfälische Wilhems-Universität Münster
Institut für Landschaftsökologie
Heisenbergstraße 2
D-48149 Münster
Tel.: +49 (0) 251 83 33 996
Fax: +49 (0) 251 83 38 338
E-Mail: mattesh@uni-muenster.de
Web: http://www.uni-muenster.de/Biozoenologie/