引种降香黄檀和顶果木对石漠化山区土壤磷素转化及其有效性的影响

我国西南岩溶区石漠化严重，植被覆盖率低，土壤贫瘠。植被恢复作为一项重要的生态治理措施，在提高土壤养分有效性，增加生物多样性和改善生态环境等方面发挥着极其重要的作用。以广西马山县经过8年植被恢复的4种样地类型(降香黄檀纯林；顶果木纯林；降香黄檀/顶果木混交林；相邻的天然灌草丛作为对照组)为研究对象，探讨了引进固氮树种(降香黄檀和顶果木)及其种植模式对石漠化山区土壤磷素转化及其有效性的影响。研究结果表明：(1)降香黄檀/顶果木混交林土壤的有机质(SOM)、硝态氮(NO~-₃-N)、有效磷(AP)、微生物生物量碳(MBC)、微生物生物量氮(MBN)和微生物生物量磷(MBP)含量均显著高于对照(P<0.05);降香黄檀/顶果木混交林、顶果木纯林和降香黄檀纯林的全磷(TP)相比于对照组更易转化为AP,其中以降香黄檀/顶果木混交林的效果最佳。(2)相关分析结果表明，土壤NH~+₄-N、NO~-₃-N和MBN与AP分别呈显著线性正相关(P<0.05),MBN与MBP呈极显著线性正相关(P<0.01)。(3)引种降香黄...

Effects of introducing Dalbergia odorifera and Acricarpus fraxinifolius on soil phosphorus transformation and availability in rocky desertification mountainous regions

Rocky desertification is serious in karst areas in southwest China, with low vegetation coverage and poor soil. As an important ecological management measure, vegetation restoration plays an extremely important role in improving the availability of soil nutrients, increasing biodiversity, and improving the ecological environment. In this study, four types of site (the pure plantation of Dalbergia odorifera; the pure plantation of Acricarpus fraxinifolius; the mixed plantation of D. odorifera and A. fraxinifolius; the adjacent natural weed field as the control) in Mashan, Guangxi were selected as the research objects after 8 years of vegetation restoration. The effects of introducing N₂-fixing tree species (D. odorifera and A. fraxinifolius) and their planting patterns on the soil phosphorus transformation and availability in rocky desertification mountainous regions were discussed. The results showed that:(1) the contents of soil organic matter (SOM), nitrate nitrogen (NO₃^--N), available phosphorus (AP), soil microbial biomass carbon (MBC), soil microbial biomass nitrogen (MBN), and soil microbial biomass phosphorus (MBP) in the mixed plantation of D. odorifera and A. fraxinifolius were significantly higher than those of the control (P<0.05). The total phosphorus (TP) of the mixed plantation of D. odorifera and A. fraxinifolius, the pure plantation of A. fraxinifolius and the pure plantation of D. odorifera could be easily transformed into AP than control, among which the mixed plantation of D. odorifera and A. fraxinifolius had the best effect. (2) The results of correlation analysis showed that NH₄⁺-N, NO₃^--N, and MBN had significant linear positive correlation with AP respectively (P<0.05), while MBN and MBP had extremely significant linear positive correlation (P<0.01). (3) After introducing D. odorifera and A. fraxinifolius, the soil inorganic phosphorus fractions in all sites changed, and the contents of various inorganic phosphorus in the mixed plantation of D. odorifera and A. fraxinifolius and the pure plantation of A. fraxinifolius increased significantly (P<0.05). (4) Finally, the redundancy analysis (RDA) indicated that MBP, SOM, and MBN would be the main factors affecting the changes of soil inorganic phosphorus fractions (P<0.05). Overall, D. odorifera and A. fraxinifolius could improve soil nutrient and phosphorus availability in rocky desertification mountain regions to a certain extent, among which the mixed planting pattern (the mixed plantation of D. odorifera and A. fraxinifolius) had the most significant effect. The purpose of the study could provide theoretical basis and practical support for the application of N₂-fixing tree species in the ecological restoration and reconstruction of rocky desertification.