模拟喀斯特异质性小生境下三叶鬼针草地上地下协同生长对策

模拟在喀斯特异质生境下，通过随机区组实验，研究三叶鬼针草（Bidens pilosa L.）在两种土壤生境（浅而宽、深而窄）和3种水分处理（对照、减水50%、减水70%）下植物的地上和地下生长关系及生物量分配格局。结果显示：（1）两种生境中三叶鬼针草的地上生长（株高、地径、叶面积、叶生物量）与地下根系生长（根长、根表面积、根体积、根生物量）均随着施水量的减少而降低；叶面积比率随着施水量的减少而增加；根质量比在浅而宽土壤生境中呈先增后减的趋势，而在深而窄土壤生境中呈增加趋势。（2）两种生境中三叶鬼针草的地上生物量与地下根系生物量、叶面积与根长、叶面积与各层根系生长均呈显著正相关关系。但在浅而宽土壤生境中，三叶鬼针草的地上生物量与各土层根系生物量均呈显著正相关，而在深而窄土壤生境中，地上生物量仅与中上土层根系生物量呈显著正相关。研究表明三叶鬼针草在不同生境中均具有较好的地上地下协同生长对策，在增强对地下资源获取的同时也增强了对地上资源的获取。在浅而宽土壤生境中，三叶鬼针草通过协调根系的横向拓展能力与植物叶片的生长来应对快速的干旱缺水；在深而窄土壤生境中，植株能较好地协调根系向下拓展能力与地上叶面积的生长，更好地利用土壤深层的水分资源。

Synergistic aboveground-belowground growth of Bidens pilosa L. in heterogeneous karst habitats

Based on simulation of heterogeneous karst habitats, the aboveground and belowground growth relationship of Bidens pilosa L. and biomass distribution patterns under two soil habitats (SW: shallow and wide; DN: deep and narrow) and three water treatments (W100%: control; W50%: water reduction by 50%; W30%: water reduction by 70%) were investigated through a randomized block group experiment. Results showed that: (1) Aboveground growth (plant height, ground diameter, leaf area, leaf biomass) and root growth (root length, root surface area, root volume, root biomass) in both habitats decreased with the decrease in applied water; the leaf area ratio increased with the decrease in applied water; and the root-to-mass ratio increased at first and then decreased in the SW soil habitat, but increased in the DN soil habitat. (2) Aboveground biomass and root biomass, leaf area and root length, and leaf area and root growth in each layer of the two habitats showed significant positive correlations. In SW soil habitats, the aboveground biomass of B. pilosa showed a significant positive correlation with the root biomass in each soil layer, whereas in the DN soil habitat, the aboveground biomass was only significantly positively correlated with the middle and upper soil layer root biomass. Studies have shown that B. pilosa exhibited good synergistic aboveground and belowground growth strategies in different habitats. When enhancing the acquisition of belowground resources, B. pilosa also enhanced the acquisition of aboveground resources. In SW soil habitats, B. pilosa coped with rapid drought and water shortages by coordinating the lateral expansion ability of the root system and growth of plant leaves; in DN soil habitats, plants coordinated the downward expansion ability of the root system and expansion of the leaf area to better utilize deep water resources in the soil.