 |
| Titel |
Accumulation of organic carbon, its turnover and CO2 emissions from soils under three vegetation types: results of a lysimeter study |
| VerfasserIn |
Anna Gunina |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250046058
|
|
|
|
|
|
| Zusammenfassung |
| Prediction the future CO2 emissions imply understanding of carbon (C) cycle and C turnover
in soils under the different vegetation. One of the problems limiting the explanatory
power of many studies is the fact that the soil age is not known exactly and the
most studies accept that the soils are more or less under steady state. However, the
intensity of soil processes depends on soil age and equilibrium between present
vegetation and soils and so, if we compare processes under different vegetation
we have to select the soils with similar formation period. The second important
factor affecting explanatory power of our experiments is the soil parent material
that should be identical by comparison of CO2 fluxes from soils under different
vegetation.
To meet these challenges we studied C cycle in a unique long-term lysimeter experiment
started 43 years ago on 3 x 3 m2 plots with 3 vegetation types: coniferous forest (Picea
abies), broadleaf forest (Acer platanoides and Quercus robur) and grassland (totally 10
grasses and herbs species with dominance of Lolium perenne). The soil parent material for
lysimeter filling was loam originated from the coverloam of the last Waldai glaciation; the
loam was free of stones, carbonates and organic C. So, during 43 years the soils were
developed on identical parent material under three vegetation types. Soil samples were
collected in 2010 from 0-5; 5-10; 10-15 and 15-20 cm depths under three vegetation types
and roots were completely removed before analyses by sieving. All soils were analyzed for
total organic C (SOC), CO2 efflux under controlled conditions, and microbial biomass C
(Cmic) in the bulk soil and in three aggregate classes (> 2000 μm, 250-2000 μm and < 250
μm).
CO2 production rates from soil under grassland were for 73% in 0-10 and 45% 10-20 cm
lower than under broad leaf forest. CO2 production rates from soil under coniferous forest
were for 48% and 52% (in 0-10 and 10-20 cm, respectively) lower than under broad leaf
forest. The respiratory quotient (qCO2, the ratio between CO2 production rates and
Cmic) in the soil under grassland was 0.74 μg C mg-1 Cmic h-1 in 0-5 cm and
increased to 1.58 μg mg-1 Cmic h-1 in 15-20 cm. qCO2 under the broad leaf forest
ranged from 1.34 in upper layer to 3.41 μg mg-1 Cmic h-1 in 15-20 cm layer.
The ratio of Cmic to SOC was highest in soils under grassland: 1.9% and lowest
under the broad leaf forest 0.9% in 0-5 cm layer. These parameters for soil under
coniferous forest were between that under grassland and broad leaf forest. The soil under
the broad leaf forest had the highest SOC (64.9 g kg-1 and 24 g kg-1 in the 0–5
cm and 5-10 cm layers, respectively). In 10-15Â cm and 15-20Â cm layers the SOC
content ranged from 2 to 7 g kg-1. The lowest SOC was under the grassland – 5-10 g
kg-1 (for 0-5 cm). The highest rates of carbon accumulation comprise the 1.5 g
kg-1year-1.
The SOC in separated aggregate fractions was highest in small macroaggregates
(250-2000 μm) and ranged from 21 to 63.5 g kg-1 in the 0–5 cm layer up to 4.0–7.1 g kg-1
in the 5–10 cm layer under the broad leaf and coniferous forest, respectively. In contrast, the
SOC content under grassland was highest in large macroaggregates amounting for 3.1 to 5.8
g kg-1 in different layers. CO2 production from and microbial biomass in individual
aggregate fractions showed further differences in C stabilization under the investigated
vegetation types and allowed to estimate turnover rates of microbial biomass and of
SOC.
This work was financially supported by the Russian Federal Programme «Scientific
and scientific-pedagogical personnel» (2009-2013). State contract number P307 |
|
|
|
|
|
|