| The carbon(CO2 and CH4) emission fluxes, vegetation net primary productivity and annual carbon sequestration were studied from seven kinds of natural wetlands(Carex schmidtii marsh-C, Betula ovalifolia-C.schmidtii shrub swamp-G, Alnus sibirica-C.schmidtii swamp-M, B.platyphylla-C.schmidtii swamp-B, Larix gmelinii-C.schmidtii swamp-L-T, L.gmelinii-moss swamp-L-X and L.gmelinii-Sphagnum spp. Swamp-L-N)in Xiaoxing’anling of China by using static chamber gas chromatography method and Multi N/C 3100, HT 1300 Solids Module(Analytik Jena AG, Germany)and the relative growth equation method, so as to evaluate the carbon source or sink of nature forested wetlands based on net ecosystem carbon balance. The results showed that:①seasonal dynamics and seasonal distribution of CH4 emission fluxes from seven kinds of nature wetlands in Xiaoxing’anling could be divided into three or two types, respectively: single-peak type(C and B), multi-peake type(M and B)and emission and absorption alternating type(L-T, L-X, L-N) or summer>spring≈fall≈winter mono peak type(C, G, M, B) and summer≈spring≈fall≈winter steady type(L-T, L-X, L-N). CH4 emission flux from M was the highest of seven kinds of wetlands types(0.01-7.76 mg·m-2·h-1)(which was significantly higher than others 1.0～1291.7 times, P＜0.05), that from C, G, B were in the medium level(which were higher than L-T, L-X, L-N 17.7-649.2 times, yet only G was significant higher), and that from L-T, L-X, L-N were lowest in all types;②seasonal dynamics and seasonal distribution of CO2 emission fluxes from seven kinds of nature wetlands could be divided into two or three types, respectively:single-peak type(M, B, L-T)and double peak type(C, G, L-X, L-N)or summer>spring≈fall>winter type(C), summer>spring>fall≈winter typc(G, M, L-T, L-N), and summer>spring>fall>winter type(B, L-X). CO2 emission flux from G was the highest of seven kinds of wetlands types(157.40-231.06 mg·m-2·h-1)(which was significantly higher than five forested wetlands types 28.7%～46.8%, P＜0.05), that from C was in the medium level(which was higher than five forested wetlands types 7.4%～22.5%, P>0.05), and that from five forested wetlands types were lowest;③CH4 emission fluxes from C, G, M, B, L-N were controlled by soil temperature(such as 30～40cm,5～40cm,5～40cm,10～40cm,0～10cm soil temperature respectively), but that from L-T and L-X had no significant correlation with 0-40cm soil temperature. CO2 emission fluxes from C, G, M, L-T were controlled by air temperature and soil temperature(such as 0～30cm, 0～40cm,0～30cm,0～10cm soil temperature respectively), but that from L-T and L-X were controlled by air temperature, water table level, and soil temperature(0-30cm,0～20cm, 0-30cm soil temperature respectively);④The vegetation net primary productivity and annual carbon sequestration of C were the highest of seven kinds of wetlands types(4.42-15.44 t·hm-2·a-1 and 2.05～6.75 tC·hm-2·a-1)(which was significantly higher than others 65.4%-249.3%, P＜0.05), those of G, B, L-T, L-N, L-X were in the medium level(which were higher than M 77.1%～108.1%, P＜0.05), while M was lowest in all types;⑤the sources or sinks of carbon were significantly different among the seven kinds of natural wetlands types(-2.32-2.09 tC·hm-2·a-1), for example, C was a stronger sink of carbon(which was stronger than B and L-N 15.1-68.7 times, P<0.05), B and L-N were weaker sinks of carbon, yet M was a stronger source of carbon(which stronger than L-T and L-X 4.7～6.5 times, P＜0.05), G was a medium source of carbon(which stronger than L-T and L-X 2.9～4.2 times, P>0.05), while L-T and L-X were weaker sources of carbon. Therefore, the carbon sources/sinks of natural wetlands have close relationship with vegetation types and their habitats in temperate Xiaoxing’anling of China(such as marsh wetlands-a stronger carbon sink, shrub wetlands-a stronger carbon source, and forested wetlands-maintaining carbon balance), because vegetation type and habitat had significant influence on both vegetation carbon sequestration and soil carbon emission process. |
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