Carbon and nitrogen contents in particle–size fractions of topsoil along a 3000 km aridity gradient in grasslands of northern China
Climate factors such as aridity significantly influence soil carbon (C) and nitrogen (N) stocks in terrestrial ecosystems. Further, soil texture plays an important role in driving changes of soil C and N contents at regional scale. However, it remains uncertain whether such changes resulted from the...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-06-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/13/3635/2016/bg-13-3635-2016.pdf |
| Summary: | Climate factors such as aridity significantly influence soil carbon (C) and
nitrogen (N) stocks in terrestrial ecosystems. Further, soil texture plays
an important role in driving changes of soil C and N contents at regional
scale. However, it remains uncertain whether such changes resulted from
the variation of different soil particle–size factions and/or the C and N
concentrations in those fractions. We examined the distribution of total C
and N in both bulk soil and different soil particle–size fractions,
including sand (53–2000 µm), silt (2–53 µm), and clay (< 2 µm), along a 3000 km
transect in arid and semi-arid grasslands of
northern China. Across the whole transect, sand content was positively and
silt content was negatively correlated with increasing aridity. Carbon
content in bulk soils (0–10 cm) ranged from 4.36 to 46.16 Mg C ha<sup>−1</sup>,
while N content ranged from 0.22 to 4.28 Mg N ha<sup>−1</sup> across different
sampling sites on the transect. The total C and N concentrations and
contents in bulk soils as well as in the three particle–size fractions
tended to be negatively correlated with aridity. The concentrations and
contents of total C and N in bulk soils were positively correlated with silt
and clay contents and negatively correlated with sand content. Positive
correlations were observed between the concentrations and contents of C or N
in bulk soils and the C or N concentrations in the three soil particle–size
fractions. By characterizing such a large scale aridity gradient, our
results highlight that aridity would decrease soil C and N contents both by
favoring increased sand content and by decreasing C and N concentrations in
all the three soil fractions. These patterns thus have significant
implications for understanding soil C and N sequestration under scenarios of
increasing aridity in global drylands that are predicted to occur this
century. |
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| ISSN: | 1726-4170 1726-4189 |