Carbon sequestration in conditions of Slovak republic and Danube floodplains Andrej Kovarik

Country conditions of Slovakia  Mild climate with annual average about 10°C in southern parts  Initially almost fully forested  Recently 41% landscape surface forested  Only fragments - about 2% are floodplain forests  River regulation has been the principal immediate cause of wetland loss and consequently also loss of biodiversity.  Most devastated and endangered forest habitat

khaInitial2005 FinalForestsGrasslandsCroplandsOther Final area Forests188023,9029,01932,9 Grasslands0,0793,073,526,7881,5 Croplands0,00,01409,70,01408,7 Other357,046,8668,6680, Initial area 1916,0822,01526,0639,64903,6 Net change 16,959,5-117,340,80,0 Land use matrix

Land use changes

Carbon sequestration in Gg Carbon sequestration in Gg

Methodology, data sources and calculations Results from national forest statistics, NFI and soil inventory (forest and agriculture soils) Non-CO2 gases – forest fires, liming of agricultural soils Calculations from living biomass, soil organic C, biomass burning and liming

Forest land – living biomass Wood increment – based on biomass expansion factors (BEFs) calculation according to individual tree species Wood harvest from national forest statistics Calculations based on annual data

BEFs and C-fraction – tree species in Slovak conditions C - fraction Biomass Conversion/ExpansionFactor Tree species Tree species of dm t dm/m 3 Picea abies Spruce Abies alba Fir Pinus sp. Pine Larix decidua Larch Other coniferous Quecus robur, petr. Oak Fagus sylvatica Beech Carpinus betulus Hornbeam Acer sp. Maple Fraxinus excelsior Ash0.491 Ulmus sp. Elm0.491 Quercus cerris Pubescent oak Robinia pseudoac. Robinia Betulus sp. Birch Alnus sp. Alder Tilia sp. Linden Populus sp. Poplar

Soil organic carbon Calculations for 4 land use changes SOC data from national soil inventory (mainly for forest and agricultural soils) Calculation units – soil types Calculations based on annual data Default time period T = 20 years

SOC for land use and soil types Soil Soil Carbon (t C/ha) type Land use category Forest Land GrasslandCropland Other Land* Regosol8765 Ranker Rendzina Chernozem Fluvi-gleyic phaozem Orthic Luvisol Luvisol Cambisol Podzol Albo-gleyic Luvisol Fluvisol

Carbon sequestration in floodplain forests conditions  Not evalueted yet in Slovakia  The soil, along with geologic formations, is recognized as the most stable reservoirs for storing C  Organic carbon content is significantly greater in hydric soils than in non-hydric soils.  Danube floodplain forests stands mostly on gravel based – mineral soils

 Carbon content of the mineral soil is increasing with successional stage of the floodplain chronosequence.  Increasing production of forest biomass per se may not necessarily increase the SOC stocks.  Rate of soil organic carbon (SOC) sequestration, and the magnitude and quality of soil C stock depend on the complex interaction between climate, soils, tree species and management, and chemical composition of the litter

 In disturbed sites, for instance suitable for re- naturalization, regression analyses indicates that it may take over 50 years for carbon levels to reach 75% of levels on reference site  Many parts of the Danube floodplains are managed as intensive hybrid poplar plantations  Monocultures had reduced biodiversity significantly - plantations provides habitat only for some species, often non-native and invasive ones.

Connection with wetlands Connection with wetlands  wetlands which are closely connected with floodplain forests, comprise a small proportion of earth’s terrestrial surface, but they contain a significant proportion of terrestrial carbon pool  Always thing of both!  Significant amount of carbon stored in wetland soils, peats, litter, and vegetation – 500 – 700 GT globaly. Globaly the ammount stored in wetlands may approach the total amount of atmospheric carbon that is estimated at 753 GT!

 wetlands growing on mineral soils associated with riverine systems - like here in Danube floodplains, have typically higher productivity and standing biomass (so also carbon sequestration) than fens and bogs which have organic soils.

Carbon fluxes – inputs  Organic matter, derived from either aboveground and belowground biomass production, is the principal source of soil carbon.  Litter production in bottomland hardwood forests is usually about half of aboveground net primary productivity (NPP)  Range of aboveground NPP of bottomland hardwood forests, temperate wetland forests and floodplain forests is similar – from 20 to 2000g/m2

Aboveground NPP  Forest floor organic matter increases rapidly during early secondary succession, with a maximum of about 700 g/m2 and decreasing to 340 g/m2 during the later seral stages.  Carbon content in the forest floor also reflects this pattern, with levels greatest during early succession and declining thereafter  Changes in carbon pools of the forest floor are primarily driven by changing levels of forest floor biomass in the various stages of succession, rather than element concentrations.

 Herbaceous material declines during succession from about 75% in an early stage to <1% in the latest seral stage  Conversely, the amount of woody foliage increased from 6.7 to more than 70% in late succession.  Aboveground net primary production (NPP) in young riparian forests rapidly approached and exceeded NPP of the more mature riparian forest.  Woody debris in these riparian forests comprised a relatively small carbon pool. Aboveground NPP

 Belowground organic matter inputs are important source of soil carbon.  Range of belowground NPP varies according local hydrological conditions from about 10 to 110 %.  Stump and root biomass may reach as much as 90 % of the belowground biomass.  Important wetland, bottomland hardwood and floodplain forests soil component is mycorrhizal fungi.  Poorly drained soils have significantly higher rates of mycorrhizal fungi infection and greater belowground allocation of carbon than in better drained soils.

Carbon storage in short- rotation poplar plantations  higher soil C sequestration rates in plantation culture than in natural systems due to the higher planting densities of faster growing trees putting greater quantities of C into the soil  Studies have acknowledged the possibility of soil C accumulations in rotations for up to 30 years.  As rotation length shortens, gain in soil C can decrease and cause a long-term decline in soil C

 Various patterns of change in soil C observed  Net losses in soil C during the initial years of tree crop establishment, but increases after about 5 years growth of hybrid poplars  Rate of soil C sequestration in short rotation plantations would equal or surpass naturally regenerating woodlands.

BROZ in Danube floodplains

Changing of forest management Changing of forest management

Leaving of dead wood

Designation of new nature reserves Afforestation of arable land

Restoration of grasslands

Restoration of wetlands

Conclusion  There are environmental implications for the use of Populus and other short rotation intensive culture crops in sequestering atmospheric C by storing it in terrestrial pools  but in respect to biodiversity, and real nature conservancy, only on new unforested sites – for example on agrisoils along the rivers.

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