不同喀斯特土壤类型下常见蕨类植物氮磷养分策略差异及其与土壤养分供给关系

蕨类植物是喀斯特生态系统的先锋植物,研究其对瘠薄的喀斯特地区土壤的适应策略,对退化生态系统的恢复与重建具有重要意义。本研究以贵州省植物园内地带性黄壤、非地带性石灰土上均有分布的常见蕨类植物毛蕨[Cyclosorus interruptus (Willd.) H.Ito]、剑叶凤尾蕨(Pteris ensiformis Burm.)和金粉蕨[Onychium siliculosum (Desv.) C.Chr.]为试验材料,研究2种喀斯特土壤类型下3种常见蕨类植物氮磷养分策略的差异,及其与土壤氮磷养分供给的关系。结果表明：①石灰土上蕨类植物根系分泌的有机酸主要为酒石酸、草酸和苹果酸,黄壤上为酒石酸、苹果酸和柠檬酸,且石灰土上根系分泌的有机酸总量远高于黄壤;②与黄壤上生长的蕨类植物相比,石灰土上蕨类植物干物质积累量、氮素与磷素吸收量均较高,分别高出2.7倍、30.8%和43.8%;③2种土壤条件下蕨类植物地上部分的氮(N)、磷(P)平均含量均较地下部分高;石灰土上蕨类植物地上部分N/P为13.17,黄壤上为11.35;④2种土壤条件下蕨类植物的氮素吸收量均与土壤有效磷含量呈显著正相关,说明蕨类植物对土壤氮素的吸收利用受土壤有效磷含量的限制。综上可知,蕨类植物在2种土壤类型上的氮磷养分利用与分配策略存在显著差异,其在石灰土上生长时对土壤养分循环的影响较黄壤上大。

Differences in Nitrogen and Phosphorus Nutrients Strategies of Common Ferns under Different Karst Soil Types and Their Relationship with Soil Nutrient Supply

Ferns are pioneer plants in karst ecosystems.It is of great significance for the restoration and reconstruction of degraded ecosystems to study their adaptation strategies to barren karst soils.In this study,the common fern plants,Cyclosorus interruptus (Willd.) H.Ito,Pteris ensiformis Burm.and Onychium siliculosum (Desv.) C.Chr.,distributed on both zonal yellow soil and non-zonal calcareous soil in Guizhou Botanical Garden,were used as test materials.The differences of nitrogen and phosphorus nutrient strategies of three common ferns in two karst soil types and their relationship with soil nitrogen and phosphorus nutrient supply were studied.The results showed that: ①Tartaric acid,oxalic acid and malic acid were the main organic acids secreted by the roots of ferns on calcareous soil,while tartaric acid,malic acid and citric acid were the main organic acids secreted by the roots of ferns on yellow soil.The total amount of organic acids secreted by roots on calcareous soil was much higher than that on yellow soil.② Compared with the ferns growing on yellow soil,the dry matter accumulation,nitrogen and phosphorus uptake of ferns on calcareous soil were higher,which were 2.7 times,30.8% and 43.8% higher than those on yellow soil,respectively.③The average contents of nitrogen and phosphorus in the aboveground part of ferns were higher than those in the underground part under the two soil conditions.The N/P ratio of the aboveground part of ferns on calcareous soil was 13.17,and that on yellow soil was 11.35.④The nitrogen uptake of ferns under the two soil conditions was significantly positively correlated with the soil available phosphorus content,indicating that the absorption and utilization of soil nitrogen by ferns was limited by the content of available phosphorus in soil.In summary,there were significant differences in the utilization and distribution strategies of nitrogen and phosphorus nutrients in ferns on the two soil types,and their effects on soil nutrient cycling were greater on calcareous soil than on yellow soil.