Influences of Land Use/Cover Types on Nitrous Oxide Emissions during Freeze-Thaw Periods from Waterlogged Soils in Inner Mongolia
نویسندگان
چکیده
Nitrous oxide emissions during freeze/thaw periods contribute significantly to annual soil N2O emissions budgets in middle- and high-latitude areas; however, the freeze/thaw-related N2O emissions from waterlogged soils have hardly been studied in the Hulunber Grassland, Inner Mongolia. For this study, the effects of changes in land use/cover types on N2O emissions during freeze-thaw cycles were investigated to more accurately quantify the annual N2O emissions from grasslands. Soil cores from six sites were incubated at varying temperature (ranging from -15 to 10°C) to simulate freeze-thaw cycles. N2O production rates were low in all soil cores during freezing periods, but increased markedly after soil thawed. Mean rates of N2O production differed by vegetation type, and followed the sequence: Leymus chinensis (LC) and Artemisia tanacetifolia (AT) steppes > LC steppes ≥ Stipa baicalensis (SB) steppes. Land use types (mowing and grazing) had differing effects on freeze/thaw-related N2O production. Grazing significantly reduced N2O production by 36.8%, while mowing enhanced production. The production of N2O was related to the rate at which grassland was mowed, in the order: triennially (M3) > once annually (M1) ≥ unmown (UM). Compared with the UM control plot, the M3 and M1 mowing regimes enhanced N2O production by 57.9% and 13.0% respectively. The results of in situ year-round measurements showed that large amounts of N2O were emitted during the freeze-thaw period, and that annual mean fluxes of N2O were 9.21 μg N2O-N m-2 h-1 (ungrazed steppe) and 6.54 μg N2O-N m-2 h-1 (grazed steppe). Our results further the understanding of freeze/thaw events as enhancing N2O production, and confirm that different land use/cover types should be differentiated rather than presumed to be equivalent, regarding nitrous oxide emission. Even so, further research involving multi-year and intensive measurements of N2O emission is still needed.
منابع مشابه
Response of N2O emissions to biochar amendment in a cultivated sandy loam soil during freeze-thaw cycles
In the last decade, an increasing number of studies have reported that soil nitrous oxide (N2O) emissions can be reduced by adding biochar. However, the effect of biochar amendment on soil N2O emissions during freeze-thaw cycle (FTC) is still unknown. In this laboratory study, biochar (0%, 2% and 4%, w/w) was added into a cultivated sandy loam soil and then treated with 15 times of FTC (each FT...
متن کاملIncreased nitrous oxide emissions from Arctic peatlands after permafrost thaw.
Permafrost in the Arctic is thawing, exposing large carbon and nitrogen stocks for decomposition. Gaseous carbon release from Arctic soils due to permafrost thawing is known to be substantial, but growing evidence suggests that Arctic soils may also be relevant sources of nitrous oxide (N2O). Here we show that N2O emissions from subarctic peatlands increase as the permafrost thaws. In our study...
متن کاملNitrous oxide emission at low temperatures from manure-amended soils under corn (Zea mays L.)
Manure fertilization of soil significantly impacts the level of nitrous oxide (N2O) emission. Despite their short duration, periods of significant N2O emissions during soil thaws in winter and spring are an important portion of the total annual emissions from agricultural lands. The goal of this study was to understand the effects of tillage, moisture content and manure application on N2O emiss...
متن کاملNitrous oxide emission from Deyeuxia angustifolia freshwater marsh in northeast china.
Here we report N(2)O emission results for freshwater marshes isolated from human activities at the Sanjiang Experimental Station of Marsh Wetland Ecology in northeastern China. These results are important for us to understand N(2)O emission in natural processes in undisturbed freshwater marsh. Two adjacent plots of Deyeuxia angustifolia freshwater marsh with different water regimes, i.e., seaso...
متن کاملDo freeze-thaw events enhance C andN losses from soils of different ecosystems? A review
Freezing and thawing of soils may affect the turnover of soil organic matter and thus the losses of C and N from soils. Here we review the literature with special focus on: (i) the mechanisms involved, (ii) the effects of freezing temperature and frequency, (iii) the differences between arable soils and soils under natural vegetation, and (iv) the hypothesis that freeze-thaw events lead to sign...
متن کامل