石灰岩荒山造林后土壤养分与活性碳含量的变化

Abundance of Soil nutrients and Labile Organic Carbon Responsive to Afforestation on Abandoned Limestone Hill

在中亚热带石灰岩荒山上进行32年造林试验。结果表明:营造不同树种均可以显著增加土壤养分,其中南酸枣林下土壤全氮、全磷、水解氮和速效钾含量增幅最大,与对照相比分别增加了84.62%、55.56%、79.20%和109.76%,而梧桐土壤有效磷及有机质增幅最大,分别为292.73%和75.40%;造林明显改善了土壤有机碳库的状况,种植南酸枣、梧桐和无患子后土壤总有机碳、水溶性碳以及微生物生物量碳均明显高于对照(P<0.05),刺槐与柏木林下土壤,虽总有机碳与对照无显著差别,但2种活性碳则显著高于对照土壤(P<0.05)。长期营造林木使土壤pH值降低(从8.01降致平均7.3)。比较不同树种发现,南酸枣是改善石灰岩荒山土壤质量最好的树种之一,其次是梧桐和无患子,柏木和刺槐相对较差。

To verify the effect of afforestation on soil fertility on abandoned limestone hill, a vegetation restoration experiment with different planting types of trees had been conducted in 1974. Soil samples under different types of trees were collected in March 2006. Soil nutrients improved significantly （ P 〈 0.05） after 32-year vegetation restoration. The amount of soil total nitrogen and phosphorous, available nitrogen and potassium at Choerospondias axillaris site increased at maximum extent by 84.62%, 55.56%, 79.20% and 109.76% respectively compared with control. The great increase in soil available phosphorous and organic matter was observed at Firmiana simplex site, respectively by 292.73 % and 75.40% . The similar increasing tendency was also observed for soil organic pool, soil total organic carbon （TOC）, soil water-soluble organic carbon （WSOC） and microbial biomass carbon （MBC） were much more abundant （P 〈 0.05 ） at Ch. axillaries, F. simplex and Sapindus mukorossi sites than those at control site. Soil WSOC and MBC at Cupressus funebris and Robinia pseudoacacia sites were more abundant （ P 〈 0.05） compared with those at control site although soil TOC was found no different between them. Soil pH was lowered （from 8.01 to average 7.3） as a result of afforestion. In comparison of different treatments, it can be concluded that Ch. axillaris had the most power on improvement in soil quality, and followed by F. simplex and S. mukorossi, C. funebris and R. pseudoacaia had the least.