东祁连山不同高寒草地型牧草返青期土壤碳分布特征

以东祁连山高寒草地为样点,对土壤有机质、K2SO4浸提碳和微生物量碳(氯仿熏蒸浸提法)等进行了研究.结果表明:该区土壤有机质介于82.3～207.2 g·kg-1,植被类型影响土壤有机质含量.土壤K2SO4浸提碳介于23.61～138.81 mg·kg-1,分别占土壤有机质和土壤微生物量碳的0.03%～0.06%和9.97%～18.46%;灌丛草地中,高山柳草地显著低于杜鹃草地(P<0.05);草本草地中,珠芽蓼草地、沼泽草地和嵩草草地显著高于禾草草地(P<0.05).土壤微生物量碳介于156.19～1 182.84mg·kg-1,上层显著高于下层(P<0.05),除2005年沼泽草地外草本草地与灌丛草地间差异显著(P<0.05);微生物量碳对土壤有机质的贡献率介于0.19%～0.48%,禾草草地最低(0.19%),金露梅灌丛草地最高(0.48%),除珠芽蓼草地和沼泽草地外均为上层高于下层;且除禾草草地和嵩草草地外微生物量碳与土壤有机质、全氮和速效磷间呈显著(P<0.05)或极显著正相关(P<0.01),与土壤K2SO4浸提碳在灌丛草地呈显著正相关(P<0.05),在草本草地呈极显著正相关(P<0.01),与微生物量氮、磷间呈极显著正相关(P<0.01).该结果表明微生物量碳及其对土壤有机质的贡献率在草地型闻和土层间差异明显,且与土壤有机质、K2SO4浸提碳、全氮和速效磷关系密切.

Distribution characteristics of soil carbon during forage greening in different alpine grasslands of Eastern Qilian Mountains

Rhododendrons spp. brushland (DJ), Salix cupularis brushland (GL), Dasiphoru fruticosa brushland (JL), Polygonum viviparum grassland (ZY), Grass steppe (HC), Swamp grassland (ZZ) and Kobresia grassland (SC), which designate seven different alpine grassland types in the Eastern Qilian Mountains of Qinghai-Tibetan Plateau of Western China, were selected for soil carbon investigation (including microbial biomass carbon with Fumigation Extraction Method, soil organic matter and K₂SO₄-extractable carbon). The results show that the soil organic matter varies from 82.3 to 207.2 g·kg^-1 and is influenced by vegetation type. K₂SO₄-extractable carbon and microbial biomass carbon (MBC) range from 23.61 to 138.81 mg·kg^-1 and from 156.19 to 1 182.84 mg·kg^-1 extractable carbon to soil organic matter and MBC varies from 0.03% to 0.06% and from 9.97% to 18.46% respectively. Under brushland, the value of K₂SO₄-extractable carbon under GL is lower than that under DJ. Under grassland, however, that value under HC is lower than under ZY, ZZ and SC. MBC contribution to soil organic matter ranges from 0.19% ( under HC) to 0.48% (under JL), and the value for upper layer is greater than that for the lower layer, except under ZY and ZZ. MBC, which is higher in the upper layer than in the lower layer, has significant positive correlations (at P<0.05 or P< 0.01) with soil organic matter, total nitrogen and available phosphorus under the seven vegetation types. Furthermore, MBC has significant positive correlations with K₂SO₄-extractable carbon for brushland (at P<0.05) and for grassland (P<0.01). MBC also has significant positive correlations (P<0.01) with microbial biomass nitrogen and microbial biomass phosphorus under DJ, GL, JL, ZY, HC, ZZ and SC. MBC content and its contribution to soil organic matter are commonly different among sampling sites and soil layers. Furthermore, MBC is influenced by soil organic matter, K2SO4-extractable carbon, total nitrogen and available phosphorus.