摘要
Changes in soil chemistry after invasion by bracken(Pteridium aquilinum)have been studied in heathlands,but comparable studies in meadows are lacking.We investigated if bracken invasion into P-deficient meadows alters the soil nutrient-resource pool,as well as the mechanisms behind it linked to soil processes and bracken nutrition.Furthermore,we investigated how community composition responds to differences in soil chemistry before and after the invasion.Soil and plant material sampling,along with vegetation survey,were performed during bracken peak biomass.Data analyses included analysis of variance and canonical correspondence analysis(CCA).Bracken invasion increased soil P availability,soil organic C concentration,as well as C:N,C:S and N:S ratios,while decreasing Fe and Co concentrations.Bracken pinnae were rich in P,and its rhizomes were rich in K,whereas N:P of pinnae and rhizomes was low.CCA showed contrasting abundance patterns of frequent meadow species related to P and K availability.Holcus lanatus exhibited competitive advantage under extremely low P availability.Increase in P availability under bracken may have occurred through promoting the leaching of Fe and Al.By increasing P availability for its growth and increasing N limitation for other species,bracken can gain a competitive advantage from the soil resource-niche perspective.Its ability to increase soil P availability,along with the physiological mechanisms behind its high P acquisition efficiency,seem to differentiate bracken from other species of competitive ecological strategy,which are mainly confined to nutrient-rich environments.This enabled bracken to invade P-deficient meadows.
对于欧洲蕨(Pteridium aquilinum)入侵荒地后土壤化学的变化,已经有了相关的研究,但是对于欧洲蕨入侵草地的研究却比较缺乏。本研究探讨了欧洲蕨入侵缺磷草地是否会改变土壤养分资源库,以及与土壤过程和欧洲蕨营养相关的机制。此外,还研究了欧洲蕨入侵前后群落组成对土壤化学差异的反应。在蕨菜生物量高峰期间,我们进行了土壤和植物取样以及植被调查。数据分析包括方差分析(ANOVA)和典型对应分析(CCA)。研究结果表明,欧洲蕨入侵提高了土壤磷有效性、土壤有机碳浓度以及碳氮比、碳硫比和氮硫比,同时降低了铁和钴的浓度。欧洲蕨羽片富含磷,根茎富含钾,而羽片 和根茎的氮磷比很低。典型对应分析(CCA)显示了与磷和钾有效性相关的常见草地植物物种的不同丰度模式。在磷有效性极低的条件下,绒毛草(Holcus lanatus)表现出竞争优势。欧洲蕨通过促进铁和铝的浸出提高了磷有效性。从土壤资源生态位的角度来看,欧洲蕨通过提高自身生长所需的磷有效性并且增加对其他物种的氮限制,从而获得了竞争优势。欧洲蕨提高土壤磷有效性的能力,以及其高磷获取效率背后的生理机制,似乎将欧洲蕨与其他竞争生态策略的物种区分开来,因为其他物种的生长主要局限于营养丰富的环境,因此欧洲蕨更容易入侵缺磷的草地。
