Accumulation of soil organic C and N in planted forests fostered by tree species mixture
With the increasing trend of converting monocultures into mixed forests, more and more studies have been carried out to investigate the admixing effects on tree growth and aboveground carbon storage. However, few studies have considered the impact of mixed forests on belowground carbon sequestra...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-09-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/14/3937/2017/bg-14-3937-2017.pdf |
| Summary: | With the increasing
trend of converting monocultures into mixed forests, more and more studies
have been carried out to investigate the admixing effects on tree growth and
aboveground carbon storage. However, few studies have considered the impact
of mixed forests on belowground carbon sequestration, particularly changes in
soil carbon and nitrogen stocks as a forest grows. In this study, paired pure
<i>Pinus massoniana</i> plantations, <i>Cinnamomum camphora</i>
plantations and mixed <i>Pinus massoniana</i>–<i>Cinnamomum camphora</i>
plantations at ages of 10, 24 and 45 years were selected to test whether the
mixed plantations sequestrate more organic carbon (OC) and nitrogen (N) in
soils and whether this admixing effect becomes more pronounced with stand
ages. The results showed that tree species identification, composition and
stand age significantly affected soil OC and N stocks. The soil OC and N
stocks were the highest in mixed <i>Pinus</i>–<i>Cinnamomum</i> stands
compared to those in counterpart monocultures with the same age in the whole
soil profile or specific soil depth layers (0–10, 10–20 and
20–30 cm) for most cases, followed by <i>Cinnamomum</i> stands and
<i>Pinus</i> stands with the lowest. These positive admixing effects were
mostly nonadditive. Along the chronosequence, the soil OC stock peaked in the
24-year-old stand and was maintained as relatively stable thereafter. The
admixing effects were also the highest at this stage. However, in the topsoil
layer, the admixing effects increased with stand ages in terms of soil OC
stocks. When comparing mixed <i>Pinus</i>–<i>Cinnamomum</i> plantations
with corresponding monocultures within the same age, the soil N stock in
mixed stands was 8.30, 11.17 and 31.45 % higher than the predicted mean
value estimated from counterpart pure species plantations in 10-, 24- and
45-year-old stands, respectively. This suggests that these admixing effects
were more pronounced along the chronosequence. |
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| ISSN: | 1726-4170 1726-4189 |